FGDC-STD-018-2012

Coastal and Marine Ecological Classification Standard 

Marine and Coastal Spatial Data Subcommittee

Federal Geographic Data Committee

June, 2012

Federal Geographic Data Committee FGDC-STD-018-2012

Coastal and Marine Ecological Classification Standard, June 2012

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CONTENTS

PAGE

1. Introduction..................................................................................................................... 1

1.1 Objectives ................................................................................................................ 1

1.2 Need ......................................................................................................................... 2

1.3 Scope........................................................................................................................ 2

1.4 Application............................................................................................................... 3

1.5 Relationship to Previous FGDC Standards.............................................................. 4

1.6 Development Procedures......................................................................................... 5

1.7 Guiding Principles ................................................................................................... 7

1.7.1 Build a Scientifically Sound Ecological Classification .................................... 7

1.7.2 Meet the Needs of a Wide Range of Users....................................................... 7

1.7.3 Create a Comprehensive Internally Consistent Classification.......................... 8

1.7.4 Meet Mapping Needs........................................................................................ 9

1.7.5 Create a Flexible Classification ........................................................................ 9

1.8 Maintenance Authority .......................................................................................... 10

2. Overall Structure........................................................................................................... 11

2.1 Settings................................................................................................................... 11

2.1.1 Biogeographic Setting (BS)............................................................................ 12

2.1.2 Aquatic Setting (AS)....................................................................................... 12

2.2 Components........................................................................................................... 12

2.2.1 Water Column Component (WC)................................................................... 13

2.2.2 Geoform Component (GC) ............................................................................. 13

2.2.3 Substrate Component (SC) ............................................................................. 13

2.2.4 Biotic Component (BC).................................................................................. 14

2.3 Biotopes .................................................................................................................. 14

2.4 Modifiers................................................................................................................ 14

2.5 Using the Components........................................................................................... 15

2.6 Ecological Foundation ........................................................................................... 16

2.6.1 Temporal and Spatial Variation...................................................................... 17

2.6.2 Nature of CMECS Units................................................................................. 17

3. Biogeographic Setting.................................................................................................. 19

3.1 Biogeographic Units--Estuarine System and Marine Nearshore and Offshore 

Subsystems............................................................................................................ 19

3.2 Biogeographic Units--Marine Oceanic Subsystem................................................ 20

3.3 Biogeographic Units--Lacustrine System (Great Lakes)....................................... 23

4. Aquatic Setting............................................................................................................. 24

4.1 Aquatic Setting Hierarchical Structure ................................................................... 24

4.1.1 System............................................................................................................. 24

4.1.2 Subsystem ........................................................................................................ 24

4.1.3 Tidal Zone........................................................................................................ 25

4.2 Aquatic Setting Units.............................................................................................. 25

4.2.1 Lacustrine System............................................................................................ 25

4.2.2 Estuarine System.............................................................................................. 26

4.2.3 Marine System ................................................................................................. 30
Federal Geographic Data Committee FGDC-STD-018-2012

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5. Water Column Component .......................................................................................... 32

5.1 Water Column Layers............................................................................................. 34

5.2 Salinity Subcomponent ........................................................................................... 39

5.3 Temperature Subcomponent ................................................................................... 40

5.4 Application of Water Column Layer (L), Salinity (S) and Temperature (T) 

Subcomponent Units .............................................................................................. 41

5.5 Hydroform Subcomponent Hierarchical Structure ................................................ 42

5.5.1 Hydroform Classes........................................................................................... 43

5.5.2 Hydroforms and Hydroform Types ................................................................. 43

5.6 Hydroform Subcomponent Units............................................................................ 43

5.7 Biogeochemical Feature Subcomponent................................................................. 55

5.7.1 Biogeochemical Feature Subcomponent Units................................................ 55

5.8 Water Column Component Modifiers .................................................................... 58

6. Geoform Component ................................................................................................... 60

6.1 Tectonic Setting Subcomponent ............................................................................ 61

6.2 Physiographic Setting Subcomponent ................................................................... 62

6.3 Level 1 and Level 2 Geoform Subcomponent Hierarchical Structure................... 65

6.3.1 Level 1 and Level 2 Geoforms........................................................................ 66

6.3.2 Geoform Types ............................................................................................... 66

6.4 Level 1 and Level 2 Geoform Units ...................................................................... 67

6.5 Status of Geoform Component Units..................................................................... 96

6.6 Geoform Component Modifiers............................................................................. 97

7. Substrate Component................................................................................................... 98

7.1 Commonly Used Methods for Classifying Substrate Geology.............................. 98

7.2 Application of the Substrate Component............................................................. 102

7.3 Hierarchical Structure .......................................................................................... 103

7.3.1 Substrate Origin ............................................................................................ 104

7.3.2 Substrate Classes and Subclasses.................................................................. 104

7.3.3 Substrate Groups and Subgroups.................................................................. 104

7.4 Substrate Component Units ................................................................................. 104

7.4.1 Substrate Origin: Geologic Substrate............................................................. 104

7.4.2 Substrate Origin: Biogenic Substrate............................................................. 108

7.4.3 Substrate Origin: Anthropogenic Substrate ................................................... 115

7.5 Status of Substrate Component Units.................................................................. 118

7.6 Substrate Component Modifiers.......................................................................... 118

8. Biotic Component ...................................................................................................... 119

8.1 Hierarchical Structure .......................................................................................... 120

8.1.1 Biotic Setting ................................................................................................ 120

8.1.2 Biotic Class and Subclass ............................................................................. 120

8.1.3 Biotic Group.................................................................................................. 121

8.1.4 Biotic Community......................................................................................... 121

8.2 Biotic Component Units ...................................................................................... 122

8.2.1 Biotic Setting: Planktonic Biota..................................................................... 122

8.2.2 Biotic Setting: Benthic/Attached Biota.......................................................... 136

8.3 Status of Biotic Community Units........................................................................ 181

8.4 Biotic Component Modifiers ............................................................................... 182
Federal Geographic Data Committee FGDC-STD-018-2012

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9. Biotopes ..................................................................................................................... 184

9.1 The Biotope Concept ........................................................................................... 184

9.2 Using CMECS to Classify Biotopes.................................................................... 184

9.2.1 Classifying Biotopes with Quantitative Data................................................ 185

9.2.2 Classifying Biotopes with Observational Information ................................. 185

9.3 Describing Biotopes............................................................................................. 187

10. Modifiers.................................................................................................................. 190

10.1 Anthropogenic Modifiers................................................................................... 190

10.1.1 Anthropogenic Impact ................................................................................ 190

10.2 Biogeographic Modifiers................................................................................... 191

10.2.1 Primary Water Source................................................................................. 191

10.3 Biological Modifiers.......................................................................................... 192

10.3.1 Associated Taxa .......................................................................................... 192

10.3.2 Community Successional Stage.................................................................. 192

10.3.3 Invertebrate Community Organism Size .................................................... 195

10.3.4 Productivity................................................................................................. 196

10.4 Physical Modifiers............................................................................................. 197

10.4.1 Energy......................................................................................................... 197

10.4.2 Induration.................................................................................................... 199

10.4.3 Seafloor Rugosity........................................................................................ 200

10.4.4 Small-scale Slope........................................................................................ 201

10.4.5 Substrate Descriptors.................................................................................. 201

10.4.6 Surface Pattern............................................................................................ 204

10.4.7 Tidal Regime (Amplitude).......................................................................... 205

10.4.8 Wave Regime (Amplitude)......................................................................... 206

10.5 Physicochemical Modifiers................................................................................ 206

10.5.1 Oxygen........................................................................................................ 206

10.5.2 Photic Quality ............................................................................................. 207

10.5.3 aRPD and RPD ........................................................................................... 208

10.5.4 Salinity........................................................................................................ 209

10.5.5 Temperature ................................................................................................ 209

10.5.6 Turbidity ..................................................................................................... 210

10.5.7 Turbidity Type and Provenance.................................................................. 210

10.5.8 Water Column Stability .............................................................................. 212

10.6 Spatial Modifiers................................................................................................ 212

10.6.1 Benthic Depth Zones................................................................................... 212

10.6.2 Co-occurring Elements ............................................................................... 213

10.6.3 Coral Reef Zone.......................................................................................... 215

10.6.4 Enclosure..................................................................................................... 216

10.6.5 Percent Cover Range................................................................................... 217

10.6.6 Elevation Profile ......................................................................................... 218

10.6.7 Substrate Layering ...................................................................................... 218

10.7 Temporal Modifiers........................................................................................... 219

10.7.1 Temporal Persistence .................................................................................. 219

11. A Spatial-Temporal Framework for CMECS Components..................................... 221

11.1 Why use a spatial-temporal framework? ........................................................... 222
Federal Geographic Data Committee FGDC-STD-018-2012

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11.2 Applications....................................................................................................... 223

11.3 CMECS Components in the Spatial-Temporal Framework .............................. 224

11.3.1 Biogeographic and Aquatic Settings........................................................... 224

11.3.2 Water Column Component ......................................................................... 225

11.3.3 Geoform Component .................................................................................. 226

11.3.4 Substrate Component.................................................................................. 227

11.3.5 Biotic Component ....................................................................................... 228

11.3.6 Modifiers..................................................................................................... 229

12. Applying CMECS in Data Development and Mapping .......................................... 231

12.1 Classification versus Mapping........................................................................... 231

12.2 Spatial Considerations ....................................................................................... 232

12.3 Temporal Considerations................................................................................... 232

12.4 CMECS and Spatial Data................................................................................... 232

12.4.1 Point Data..................................................................................................... 233

12.4.2 Line Data...................................................................................................... 234

12.4.3 Polygon Data................................................................................................ 234

12.4.4 Grid Data...................................................................................................... 235

12.5 Mapping CMECS............................................................................................... 236

12.6 Integrating the Components............................................................................... 237

12.6.1 Building Derived CMECS Units ................................................................. 237

12.6.2 Integrating Units in Mapping....................................................................... 238

12.7 Sharing CMECS Data ........................................................................................ 241

13. Dynamic Content within the CMECS Standard ...................................................... 243

13.1 Revising CMECS............................................................................................... 243

13.2 Peer-Review Process.......................................................................................... 243

14. Literature Cited ........................................................................................................ 245

Appendix A (Normative): CMECS Biogeographic Setting............................................ 259

Appendix B (Normative): CMECS Aquatic Setting....................................................... 261

Appendix C (Normative): CMECS Water Column Component .................................... 263

Appendix D (Normative): CMECS Geoform Component ............................................. 267

Appendix E (Normative): CMECS Substrate Component ............................................. 275

Appendix F (Normative): CMECS Biotic Component................................................... 281

Appendix G (Informative): CMECS Crosswalk with the Classification of Wetlands and 

Deepwater Habitats in the United States, FGDC-STD-004 ....................................... 305

Appendix H (Informative): CMECS Best Practices in Crosswalking............................ 315

Appendix I (Informative): CMECS Example Classification Units ................................ 325

Appendix J (Informative): CMECS Development Participants...................................... 339
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FIGURE PAGE

Figure 2.1. CMECS Settings and Components................................................................ 11

Figure 2.2. Relationship between CMECS Settings, Components, Modifiers and 

Biotopes......................................................................................................... 15

Figure 3.1. MEOW Realms, Provinces, and Ecoregions................................................. 21

Figure 3.2. Pelagic Biogeographic Provinces Identified in GOODS............................... 22

Figure 3.3. Lower Bathyl Benthic Biogeographic Provinces Proposed in GOODS ....... 22

Figure 3.4. Abyssal Benthic Biogeographic Provinces Proposed in GOODS................. 23

Figure 4.1. Aquatic Setting Hierarchy Showing System, Subsystem and Tidal Zone. ... 26

Figure 5.1. Marine Subsystems, Oceanic Water Column Layers, and Oceanic Benthic 

Depth Zones. ................................................................................................. 37

Figure 6.1. Level 2 Pockmarks Occurring on a Small, Level 2 Tidal Flat. ..................... 67

Figure 6.2. Wind Tidal Flat: Lower Laguna Madre, Texas. ............................................ 74

Figure 6.3. Mud Volcano................................................................................................. 78

Figure 6.4. Pacific Coast Tidepool, one of the Smallest Features to be Found in the 

Geoform Category......................................................................................... 84

Figure 6.5. Fringing Mollusk Reef (Made of Oysters) Below a Marsh Platform Edge. . 86

Figure 6.6. Linear Mollusk Reef (Made of Oysters) in a Shallow Estuary, Nueces Bay, 

Texas. ............................................................................................................ 86

Figure 6.7. Patch Mollusk Reefs (Made of Oysters) in Hamlin Sound, South Carolina. 87

Figure 6.8. Edge of Washed Shell Mound in Espiritu Santo Bay, Texas. ....................... 87

Figure 6.9. Whale Fall: Skeleton With Hagfish............................................................... 90

Figure 6.10. Pilings Supporting an Abandoned Trestle in Humboldt Bay, California.... 95

Figure 7.1. Sediment Grain Size Translator Diagram.................................................... 100

Figure 7.2. Ternary Diagrams for Gravel-Sand-Mud and Sand-Silt-Clay..................... 101

Figure 8.1. Siphonophore, Physalia sp. ......................................................................... 127

Figure 8.2. Branching Coral Growth Form.................................................................... 138

Figure 8.3. Encrusting Coral Growth Form. .................................................................. 140

Figure 8.4. Foliose Coral Growth Form......................................................................... 140

Figure 8.5. Massive Coral Growth Form....................................................................... 141

Figure 8.6. Plate Coral Growth Form. ........................................................................... 142

Figure 8.7. Table Coral Growth Form. .......................................................................... 143

Figure 8.8. Glass Sponge Reef: Hexactinosida Reef. .................................................... 144

Figure 8.9. Semibalanus balanoides Communities with Co-occurring Element Mobile 

Mollusks on Hard or Mixed Substrates, Littorina littorea.......................... 150

Figure 8.10. Attached Tunicates, Didemnum vexillum, British Columbia. ................... 155

Figure 8.11. Sea Pen Bed, Stylatula elongata, San Diego, California........................... 163

Figure 8.12. Bacterial Mat: Tidal Flat in Humboldt Bay, California. ........................... 168

Figure 8.13. Bacterial Decay: White Clusters of Decay Bacteria on Dead Macroalgae in 

Narragansett Bay, Rhode Island. ............................................................... 169

Figure 8.14. Macroalgae: Canopy Forming Algae, Coastal California. ........................ 172

Figure 8.15. Seagrass Bed: Florida Keys National Marine Sanctuary. ......................... 175

Figure 8.16. Emergent Tidal Marsh near Wilmington, North Carolina......................... 176

Figure 8.17. Rhizophora mangle Fringe Forest Biotic Community. ............................. 181

Figure 9.1. Illustration of how CMECS was used to define Biotopes........................... 186
Federal Geographic Data Committee FGDC-STD-018-2012

Coastal and Marine Ecological Classification Standard, June 2012

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Figure 10.1. Distribution of Benthic Community Stages. ............................................. 193

Figure 11.1. CMECS Components in a Spatial-Temporal Framework......................... 221

Figure 11.2. The Spatial and Temporal Scale of Ecological Processes (Including Natural 

and Human Disturbances). ....................................................................... 222

Figure 11.3. The Stability of Ecosystem Features as they Relate to Sampling Efforts and 

Strategies are Shown in a Spatial-Temporal Framework......................... 223

Figure 11.4. Spatial and Temporal Distribution of Biogeographic and Aquatic Settings.

.................................................................................................................. 225

Figure 11.5. Water Column Component Spatial and Temporal Distribution................ 226

Figure 11.6. Geoform Component Spatial and Temporal Distribution. ........................ 227

Figure 11.7. Substrate Component Spatial and Temporal Distribution......................... 228

Figure 11.8. Biotic Component Spatial and Temporal Distribution.............................. 229

Figure 12.1. Sediment Grab Samples: Apalachicola Bay, Florida. ............................... 233

Figure 12.2. Shoreline Characterization. ....................................................................... 234

Figure 12.3. Shallow-water Benthic Habitats in Redfish Bay, Texas. .......................... 235

Figure 12.4. MODIS Satellite Image Classified According to CMECS WC Salinity 

Units, Mississippi Delta, Gulf of Mexico................................................. 236

Figure 12.5. Benthic Habitat Map for Arcata Bay, California....................................... 239

Figure 12.6. Biotic Component Map for Arcata Bay, California. ................................. 240

Figure 12.7. Substrate Component Map for Arcata Bay, California. ............................ 240

Figure 12.8. Geoform Component Map for Arcata Bay, California.............................. 241
Federal Geographic Data Committee FGDC-STD-018-2012

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TABLE PAGE

Table 1.1. Modern Coastal, Marine, and Great Lakes Habitat Classifications.................. 3

Table 1.2. Organizations Whose Personnel were Involved in Development of CMECS.. 6

Table 2.1. CMECS Settings and Components. ................................................................ 13

Table 3.1. Biogeographic Setting Classification Structure.............................................. 19

Table 4.1. Aquatic Setting Classification Structure......................................................... 24

Table 5.1. Water Column Classification Structure. ......................................................... 34

Table 5.2. Categories and Ranges for the Salinity Subcomponent.................................. 40

Table 5.3. Categories for Water Temperature. ................................................................ 41

Table 6.1. Geoform Component Classification Structure................................................ 61

Table 7.1. Mineral Grain Size Descriptors for CMECS .................................................. 99

Table 7.2. Substrate Component Classification Structure. ............................................ 103

Table 8.1. Biotic Component Classification Structure. ................................................. 119

Table 10.1. Anthropogenic Impacts Modifier................................................................ 190

Table 10.2. Primary Water Source Modifier. ................................................................ 192

Table 10.3. Community Successional Stage Modifier................................................... 194

Table 10.4. Invertebrate Community Organism Size Modifier. .................................... 196

Table 10.5. Phytoplankton Productivity Modifier. ........................................................ 197

Table 10.6. Macrovegetation Productivity Modifier. .................................................... 197

Table 10.7. Energy Direction Modifier.......................................................................... 198

Table 10.8. Energy Intensity (Current) Modifier........................................................... 199

Table 10.9. Energy Type Modifier. ............................................................................... 199

Table 10.11. Rugosity Modifier..................................................................................... 201

Table 10.12. Slope Modifier. ......................................................................................... 201

Table 10.13. Substrate Descriptor Modifier. ................................................................. 202

Table 10.14. Surface Pattern Modifier........................................................................... 204

Table 10.15. Tidal Regime (Amplitude) Modifier......................................................... 205

Table 10.16. Wave Regime (Amplitude) Modifier........................................................ 206

Table 10.17. Oxygen Regime Modifier. ........................................................................ 207

Table 10.18. Photic Quality Modifier. ........................................................................... 207

Table 10.19. aRPD Depth Modifier............................................................................... 209

Table 10.20. Salinity Regime Modifier. ........................................................................ 209

Table 10.21. Temperature Range Modifier.................................................................... 210

Table 10.22. Turbidity Modifier. ................................................................................... 210

Table 10.23. Turbidity Type Modifier........................................................................... 211

Table 10.24. Turbidity Provenance Modifier. ............................................................... 211

Table 10.25. Water Column Stability Regime Modifier................................................ 212

Table 10.26. Benthic Depth Zone Modifier................................................................... 213

Table 10.27. Coral Reef Zone Modifier......................................................................... 215

Table 10.28. Enclosure Modifier. .................................................................................. 217

Table 10.29. Percent Cover Modifiers........................................................................... 218

Table 10.30. Elevation Profile Modifier........................................................................ 218

Table 10.31. Persistence Modifier. ............................................................................... 220
Federal Geographic Data Committee FGDC-STD-018-2012

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Federal Geographic Data Committee FGDC-STD-018-2012

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1. Introduction

The past 150 years have witnessed the steady improvement in society’s ability to access 

and monitor the environment, observe systems in great detail over long periods of time, 

compile and analyze the resulting data, and display findings with great sophistication. In 

step with these developments, numerous approaches have been proposed for describing 

and classifying ecosystems and biological communities. In the United States, noteworthy 

strides have been made in establishing standards for terrestrial systems, National 

Vegetation Classification Standard, FGDC-STD-005-2008 (FGDC 2008), ecological 

systems (Comer et al. 2003), freshwater systems (Higgins et al. 2005), and wetlands, 

Classification of Wetlands and Deepwater Habitats in the United States, FGDC-STD-004

(FGDC 1996b), and formal or informal classification strategies have gained wide 

acceptance for each. No analogous consensus has emerged for estuarine, coastal, or openocean settings. This document is submitted to the U.S. Federal Geographic Data 

Committee (FGDC) to provide a key for translating between the myriad marine 

ecosystem and community classifications available today and offer a common path to

unambiguous identifications in the future.

1.1 Objectives

The Coastal and Marine Ecological Classification Standard (CMECS)

is a catalog of terms that provides a means for classifying ecological units using a simple,

standard format and common terminology (CMECS uses the term “unit” to refer to any 

defined entity in the standard at any level of the hierarchy; “units” include seagrass bed, 

sand, lagoon, and water mass). CMECS offers a way to organize and interpret data about 

the marine environment, and it provides a common platform for inter-relating data. It 

builds upon approaches from published national, regional, and local habitat classification 

procedures, and it offers an umbrella under which a national coastal and marine 

ecological classification can grow and evolve.

CMECS allows investigators to determine the types of data to be collected. Its structure 

accommodates data from multiple disciplines, and its use is not limited to specific gear 

types or to observations made at specific spatial or temporal resolutions.

Significant attention has been paid to assure that CMECS is compatible with relevant 

FGDC-endorsed national standards—FGDC-STD-004 (FGDC 1996b), FGDC-STD-005-

2008 (FGDC 2008), and the Metadata Profile for Shoreline Data, FGDC-STD-001.2-

2001 (FGDC 2001). This compatibility is intended to facilitate studies across the 

transition between terrestrial and coastal aquatic ecosystems. Section 1.5 of this 

document provides further discussion of the relationships between existing FGDC 

standards and CMECS.
Federal Geographic Data Committee FGDC-STD-018-2012

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The ultimate goal of CMECS is to facilitate assessment, monitoring, protection, 

restoration, and management of biotic assemblages, harvested and protected species, vital 

habitats, and important ecosystem components. Thus, CMECS enhances scientific 

understanding, advances ecosystem-based and place-based resource management, and 

safeguards coastal communities.

1.2 Need

The purpose of habitat classification is “to provide a language through which data and 

information regarding habitats can be communicated and managed” (McDougall, 

Janowicz, and Taylor 2007). At a time when the complexity and significance of marine 

resource issues are mounting, the need for additional habitat observations is growing, but

the fiscal resources to address these needs are diminishing. Under such circumstances, it 

is imperative that existing and new data be used to their fullest extent. As a first step, 

there must be agreement on the identities of the ecosystems under study. Adoption of a 

national classification standard for coastal and marine ecosystems would be a major step 

toward this goal.

Many marine habitat classifications are available in the literature. Table 1.1 lists several

representative, widely applied approaches. Unfortunately, none of these provide universal 

coverage and none are universally accepted. Classifications tend to focus on specific 

geographic regions, distinct biotic groups, characteristic environmental features, or 

limited portions of the seascape. The veracity or utility of these classifications for the 

purposes for which they were developed is not at issue, but their application for wider use 

has been problematical. Parks (2002) calls for a lingua franca for marine habitat 

classification in the face of this fractionation; CMECS aspires to meet this need.

1.3 Scope

The domain of CMECS encompasses waters from the head of tide or inland incursion of 

ocean salinity to the splash zone of the coasts to the deepest portions of the oceans and 

the deep waters of the Great Lakes. This domain includes all marine and coastal waters 

under U.S. jurisdiction for which no FGDC-endorsed classification standard currently 

exists.

CMECS addresses attached or suspended biota in the water column and on or in bottom 

sediments. Scale size ranges from colonies or aggregations of microscopic organisms to 

megafauna and megaflora. CMECS addresses the grain size and composition of marine 

substrates and major structural features of the environment (geoforms and hydroforms) to 

characterize coastal and marine ecosystems. These are discussed and presented in the 

context of the major marine Biogeographic Settings.

CMECS was developed primarily for application in the territorial waters of the United 

States (including the Exclusive Economic Zone); however, its architecture and 
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underlying approach do not preclude application of the standard in other parts of the 

marine world.

Development of the units in this document has been focused on estuarine and marine 

systems. Many of the concepts and units are applicable to the Great Lakes but additional 

work is needed to develop a comprehensive list of units for this area.

Table 1.1. Modern Coastal, Marine, and Great Lakes Habitat Classifications. This 

list is not exhaustive; it references some of the more widely used approaches.

Reference Name Location

FGDC 1996b Classification of Wetlands and Deepwater 

Habitats in the United States

U.S.

Dethier 1990 A Marine and Estuarine Habitat 

Classification System for Washington State

Washington

Madley, Sargent, and 

Sargent 2002

Development of a System for Classification 

of Habitats in Estuarine and Marine 

Environments (SCHEME) for Florida

Florida

Resource Information 

Standards Committee 

2002

British Columbia Marine Ecological 

Classification: Marine Ecosections and 

Ecounits, Version 2.0

British 

Columbia, 

Canada

Connor et al. 2004 The National Marine Habitat Classification 

for Britain and Ireland

Britain and 

Ireland

Davies et al. 2004 EUNIS Habitat Classification Europe

Ministry of Fisheries 

and Department of 

Conservation 2008

Marine Protected Areas: Classification,

Protection Standard and Implementation 

Guidelines

New Zealand

Commonwealth of 

Australia 2010

National Marine Bioregionalization of 

Australia

Australia

1.4 Application

Among the most fundamental questions asked by resource managers are:

 What resources are out there?

 Where are they located?

 How abundant are they?

 How are they doing?
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The first question can be addressed using well-defined taxonomies (for species) or 

classifications (for communities and ecosystems), which provide comprehensive lists 

with definitions of potential resource units. The second and third questions can be 

answered by applying inventory, observation, and mapping techniques that enumerate 

and place the resource on the seascape. The fourth question requires condition assessment 

studies as well as status and trend monitoring. 

While CMECS is relevant to all four questions, it speaks specifically to the first question. 

The remaining questions all require that a standard classification be in place before they 

can be answered efficiently. Section 12 of this document touches on aspects of the second 

and third questions in regards to using CMECS in data development and mapping. 

Specific implementation and mapping guidance will be offered in a companion 

document, which will be produced after the publication of CMECS. The companion 

document will include standards for sampling, inventorying, and mapping the ecological 

units described in CMECS. It also will address issues such as appropriate remote sensing 

technologies, map scales and minimum mapping units, recommended technology, timing 

and frequency of sampling, mapping conventions for “split” map classes, and best 

practices for addressing spatially and temporally variable units.

Issues pertaining to the fourth question (on habitat and resource quality) will be 

addressed in one or more subsequent documents. These will discuss methods for 

assessing and monitoring the ecological integrity and condition of the units defined in 

CMECS.

1.5 Relationship to Previous FGDC Standards

CMECS strives to accommodate all relevant data, to facilitate the use of historical data in 

combination with data from ongoing or future activities, and to be compatible with or 

complementary to applicable FGDC standards. Many refinements (discussed below) were 

made to align CMECS in this fashion. 

At the highest level of the organization, CMECS adopts the terms Marine System,

Estuarine System, and Lacustrine System; these corresponds to terms found in FGDCSTD-004 (FGDC 1996b), although some modifications were made the Estuarine 

System’s boundaries. The CMECS Estuarine System extends upstream to the head of tide 

or to waters of salinity lower than 0.5, whichever is most inland. Downstream, the 

Estuarine System extends to an imaginary line closing the mouth of the river, bay, or 

sound at the seaward end of the estuary. Head of tide is identified in accordance with 

FGDC-STD-001.2-2001 (FGDC 2001):

“The inland or upstream limit of water affected by the tide. For 

practical application in the tabulation for computation of tidal datums, 

head of tide is the inland or upstream point where the mean range 

becomes less than 0.2 foot. . .”
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CMECS subsystems provide more delineation than those proposed in FGDC-STD-004

(FGDC 1996b), which permits the capture of significant ecological distinctions. For 

example, in FGDC-STD-004, Tidal Riverine is a subsystem of the Riverine System (nontidal freshwater). However, since CMECS does not address Riverine System

environments, Tidal Riverine is adopted to delineate subsystems of the CMECS Estuarine 

System. Tidal Riverine portions of an estuary include those areas where ocean-derived 

salts measure less than 0.5 during the period of average annual low flow, upriver to the 

head of tide, where the mean tidal range becomes less than 0.2 foot or 0.06 meters 

(FGDC 2001).

The CMECS Substrate Component (SC) is compatible with sediment-related elements of 

FGDC-STD-004 (FGDC 1996b). The Soil Geographic Data Standard, FGDC-STD-006 

(FGDC 1997) is referenced in the SC for the benefit of investigators concerned with

marine soils. Marine sediments traditionally have not been considered soils; hence, the 

SC follows the approaches of Wentworth (1922) to define sediment particle sizes and 

Folk (1954) to describe mixes.

Classes and subclasses of the Biotic Component (BC) are determined by the dominant 

biota (defined as most abundant in terms of percent cover) of the substrate. These closely 

track units identified in FGDC-STD-004 (FGDC 1996b), where the classifications 

coincide in domain, but refer to Appendix G for a comparison of departures from the

earlier standard. 

Some BC subclasses are equivalent to and provide good linkages with the formation, 

group, and association levels of FGDC-STD-005-2008 (FGDC 2008). A protocol for the 

addition of new biotic groups and biotopes is included in CMECS (Section 13). This 

protocol is modeled on the one proposed in FGDC-STD-005-008, and it also draws from 

the approach outlined in Marine Habitat Classification for Britain and Ireland (Connor et 

al. 2004).

1.6 Development Procedures

CMECS was developed based on literature review, expert opinion, field testing, and peer 

review. To date, CMECS is not based on quantitative analysis of new data, although 

analysis of field-collected, quantitative data across the range of coastal and marine 

environments is a long-term goal.

Development of the standard began in the late 1990s. Previous versions of CMECS 

(Madden and Grossman 2004; Madden, Grossman, and Goodin 2005; FGDC 2010) and a 

precursor classification framework (Allee et al. 2000) were developed with the assistance 

of over 100 coastal and marine habitat experts, who represented agencies of federal, state 

and local governments, academia, non-governmental organizations, and industry. 

Contributors included scientists from the United States, Canada, Australia, and several 

European countries. Expert input was collected via four major workshops and via

extensive reviews by internal and external experts.
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As CMECS matured, efforts were made to encourage pilot applications and comparisons 

(or crosswalks) with other classifications. Tests by scientists who were not directly 

involved in developing CMECS were of special interest. To date, applications across a 

variety of habitats in various parts of the United States have been undertaken. These 

applications confirmed the utility of CMECS and the basic soundness of the logic behind 

the standard. Outside the U.S., comparisons and trials of CMECS relative to local 

classifications have been done in Argentina, Australia, Canada, Chile, Denmark, 

Germany, Iran, Mexico, Norway, and Uruguay.

In mid-August 2010, a Federal Register announcement opened CMECS for a 120-day 

public comment period. Subsequently, the standard was peer reviewed by over a dozen 

scientists representing a broad range of geographic and technical expertise. 

Revisions to CMECS, including evaluating and responding to comments from the public 

and peer reviews, were the work of over thirty scientists and managers drawn from 

federal and state governments, academia, and non-governmental organizations. 

Organizations represented in this group are listed in Table 1.2. The names and affiliations 

individuals who commented on or assisted with the final development of CMECS appear 

in Appendix J.

Table 1.2. Organizations Whose Personnel were Involved in Development of 

CMECS. 

Type of Organization Organization Name

U.S. Government National Oceanic and Atmospheric Administration 

Environmental Protection Agency 

U.S. Geological Survey

U.S. Fish and Wildlife Service

National Park Service

U.S. Army Corps of Engineers

State Government Massachusetts Division of Marine Fisheries

Texas Parks and Wildlife Department

Oregon Coastal Management Program

Academia Florida International University

Texas A&M University

University of Miami

University of Rhode Island

University of Southern Mississippi

Virginia Institute of Marine Science
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Type of Organization Organization Name

Nongovernmental 

Organizations

NatureServe

The Nature Conservancy

1.7 Guiding Principles

Five central premises directed the development and testing of CMECS.

1.7.1 Build a Scientifically Sound Ecological Classification

CMECS is based on the best available scientific knowledge about the relationships 

between the environment and the biota. Distinctions between units in CMECS were 

chosen specifically to reflect factors believed to shape biological communities. This is 

true for the Biotic Component (BC) as well as for the abiotic components.

Many of the common, pre-existing classification schemes were used to inform CMECS 

units. This process included drawing upon local or regional scientific studies to illustrate 

the specific environmental patterning of groups of units (e.g., local studies on lichen 

zonation [Fletcher 1973]), as well as considering comprehensive classifications 

developed for individual states and countries (see examples in Table 1.1). The intent of 

this effort was to take advantage of existing information and arrange it into a consistent, 

more broadly applicable framework. A common framework allows legacy datasets and 

new data to be incorporated into a single structure, which will ensure that existing 

scientific data and knowledge are preserved and available for future use.

1.7.2 Meet the Needs of a Wide Range of Users

The audience for CMECS includes coastal managers and planners, academic scientists, 

and educated lay users. Such users are drawn from a broad variety of backgrounds, 

including biology, geology, oceanography, applied mathematics, engineering, and 

mapping. CMECS is designed to meet the varied needs of this broad audience. It provides 

detailed units for those who require specific knowledge of the components, as well as 

more general units for those who need less specificity.

CMECS also is developed to address applications whose scales range from local to 

national to global. Most classification systems are keyed to regional or local applications. 

Their operational scales (meters to kilometers) reflect the scales at which state and local 

governments monitor and manage resources. Local and regional approaches do not 

readily support national comparisons across ecosystems, methods of observation, or 

analytical techniques. CMECS is designed to provide the specificity needed by local 
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applications, while at the same time allowing aggregation and assessment across diverse 

systems at regional, national or global scales—without loss of utility at local levels.

CMECS is designed to operate at multiple spatial scales in order to allow users to address 

different objectives. For example, a federal management agency seeking to identify and 

catalog the benthic ecosystems of the large estuaries in North America may restrict its 

analysis to the upper three levels of the Biotic Component (BC). On the other hand, a

local agency classifying ecosystems within a single estuary may want to use the lower 

two or three levels of the BC hierarchy. Using CMECS as a common standard, both 

agencies will be able to organize and compare results by applying a unified vocabulary 

within a common and interoperable data framework. The framework provides the enduser with the tools to build the bottom levels of ecosystems and biology into the larger 

conceptual framework.

1.7.3 Create a Comprehensive Internally Consistent Classification

CMECS provides a comprehensive approach to classify all recognized marine ecological 

units—similar to the Linnaean goal of classifying and describing all species on Earth (but 

without the aim of inferring evolutionary relationships). CMECS attempts to answer the 

question: What is out there? At the upper levels of each component, the lists of units—

when completely elaborated—are intended to provide complete coverage of the biota, 

substrate features, geomorphic structures, aquatic features, and biogeographic influences

that shape biological communities.

CMECS is not technology-constrained; units (especially lower-level units on the scale of 

meters) are not defined solely on what is identifiable from remote imagery or other 

currently available sensing technology. Likewise, CMECS is a classification of existing 

units—that is, those documented to exist in a given place at a given time. Therefore, 

CMECS is not constrained to units that are spatially or temporally static. Units that vary 

in time and space (such as phytoplankton blooms) provide a mapping challenge. 

However, they are classified and described in CMECS because they represent 

recognizable, consistently repeating ecological units that are of conservation and 

management value.

CMECS also strives to be internally consistent. As a rule, CMECS employs comparable 

concepts and classifiers at analogous levels within a component to the extent practical.

CMECS units are intended to be unique and non-duplicative. Every effort was made to 

define thresholds between units to avoid conceptual overlap and so that units can be 

unambiguously applied.

Clearly documented terminology is essential to a comprehensive and internally consistent 

standard. Each CMECS unit is defined in the sections for the individual components, and 

boundaries and thresholds between are identified.
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1.7.4 Meet Mapping Needs

Although CMECS units are not defined on the basis of “map-ability,” mapping is a 

primary application of the system. Each classification unit represents a measurable space,

and it can be ascribed to a specific place with defined geographic boundaries. The ability 

to map each classification unit has been considered in the process of defining the unit, 

and ease of mapping application was accommodated wherever possible. Because current 

mapping technology is limited in the details that can be interpreted, ground-based data 

collection will be required for identifying and mapping many lower-level features.

1.7.5 Create a Flexible Classification

Having a broad audience of users requires that CMECS be flexible enough to meet a 

variety of needs. CMECS is designed with multiple components to allow users to select 

the components that most effectively describe the ecological units under observation.

Within individual components, users apply CMECS at the level of specificity that best 

meets their circumstances.

Users specializing in one aspect of CMECS or in or local applications of the standard 

may be interested in tracking a finer level of detail than is offered by the standard 

catalogue of types. Two options are available, one or both of which may be used. 

CMECS includes a standard list of modifiers that allow users to further parse standard 

features according to qualities such as energy, turbidity, or characteristic structural 

components. This provides flexibility to local and specialized users. Modifiers are 

intended for broad application and add detail at all levels of the classification. The second 

option is to introduce finer, non-standard levels of classification beyond the lowest tiers 

of the CMECS components. 

Though CMECS provides clear thresholds for the boundaries between the units, some 

users applying CMECS may be interested in capturing information on additional 

characteristics of a unit that fall outside of the threshold. For example, a given area on the 

bottom might be classified according to CMECS as a seagrass bed, because of the area is 

dominated by a given seagrass species. However, that same area also may contain a 

moderate (but not dominant) cover of soft corals that are of interest to the user. CMECS 

enables users to classify the unit as a seagrass bed, while also cataloging the soft corals as 

a Co-occurring Element. This flexibility allows consistent application of the standard, 

while meeting the individual needs of the practitioner. See Section 10 for a discussion of 

this methodology.

The nature of scientific inquiry is that understanding improves over time. CMECS is a 

dynamic content standard and offers the flexibility to add or refine units based on new 

information through a moderated, peer-reviewed, transparent process. See Section 13 for 

a discussion of CMECS as a dynamic content standard.
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1.8 Maintenance Authority

The National Oceanic and Atmospheric Administration (NOAA) was assigned 

responsibility to coordinate, manage, and disseminate marine and coastal spatial data 

under the policy guidance and oversight of the FGDC. CMECS was developed under the 

authority of the Office of Management and Budget Circular A-16 (OMB 2002). Through 

the Marine and Coastal Spatial Data Subcommittee, NOAA will oversee the maintenance 

and updating of the Standard through periodic review. In addition, NOAA will oversee 

the maintenance, updating, dissemination, and implementation of CMECS, based on this 

Standard, in collaboration with member agencies, professional societies, and other 

organizations. Future revision of this Standard shall follow the standards development 

process described in the FGDC Standards Reference Model (FGDC 1996a). The dynamic 

content of the CMECS shall be updated under the direction of a national review board 

authorized by NOAA through the Subcommittee. For more information about the Marine 

and Coastal Spatial Data Subcommittee or the review board, please contact:

NOAA Coastal Services Center

Attn: FGDC Marine and Coastal Spatial Data Subcommittee

2234 South Hobson Avenue

Charleston, SC 29405-2413
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2. Overall Structure 

CMECS characterizes marine and coastal environments in terms of two settings and four 

components (Figure 2.1). Settings offer alternate but complementary approaches for 

partitioning the marine and coastal world. Components provide specific tools for 

describing observation (sampling) sites. Settings are applicable to all components.

Figure 2.1. CMECS Settings and Components.

CMECS users may employ one or both settings and one or more components to classify 

environmental units, depending on their interests, observation methods, and objectives. 

Introductory overviews of CMECS settings and components are provided below. 

2.1 Settings

CMECS provides two broad based, complementary settings within which to partition the 

coastal and marine world—the Biogeographic Setting (BS) and the Aquatic Setting (AS). 

These may be used independently or together. Each setting is described briefly below;

more complete accounts are presented in Sections 3 and 4.
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2.1.1 Biogeographic Setting (BS)

The BS identifies ecological units based on species aggregations and features influencing 

the distribution of organisms. Coastal and marine waters are organized into regional 

hierarchies composed of realms (largest), provinces and ecoregions (smallest). 

CMECS adopts the approach described by Spalding et al. (2007) in Marine Ecosystems of 

the World (MEOW) to characterize Biogeographic Settings occurring in the Estuarine 

System and in the Marine Nearshore and Marine Offshore Subsystems. MEOW is 

worldwide in coverage and identifies five realms, eight provinces, and 24 ecoregions in 

U.S. waters (Appendix A). Representative units include the Gulf of Maine/Bay of 

Fundy, Carolinian, and Southern California Bight ecoregions. 

Biogeographic Settings for the CMECS Oceanic Subsystem are defined in the Global 

Open Ocean and Deep Seabed (GOODS) Biogeographic Classification (UNESCO 2009).

As in MEOW, hierarchies composed of regions, provinces, and ecoregions are identified, 

but separate suites of terms are applied to benthic and water column habitats. Additional 

information about the BS is provided in Section 3. 

2.1.2 Aquatic Setting (AS)

CMECS also divides the coastal and marine environment into three Systems: Marine, 

Estuarine, and Lacustrine. These conform to those described in the Classification of 

Wetlands and Deepwater Habitats in the United States, FGDC-STD-004 (FGDC 1996b). 

Secondary and tertiary layers of the Aquatic Setting describe Subsystems (e.g., 

Nearshore, Offshore, and Oceanic within the Marine System) and Tidal Zones within the 

Estuarine System and Marine Nearshore Subsystem. See Section 4 for a more 

comprehensive treatment of the aquatic setting.

2.2 Components

CMECS is organized into four components to record and define the attributes of 

environmental units and biota within each setting--the Water Column Component (WC), 

the Geoform Component (GC), the Substrate Component (SC), and the Biotic 

Component (BC) (Figure 2.1). Each component is a stand-alone construct that can be 

used on its own or in combination with other components or settings. CMECS 

components include a variety of modifiers to enhance the specificity and detail of 

resulting descriptions and classifications. 

Units within the BC and SC are organized into traditional hierarchical frameworks; 

however, this is not the case for the WC and the GC. Units within each of the latter 

overlap significantly in nature and do not lend themselves to hierarchies. CMECS
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organizes the WC and GC into subcomponents that may be used on their own or in 

combination (Table 2.1)

In-depth descriptions of CMECS components are provided in Sections 5-8. Brief 

synopses of each, with examples, are presented below as an introduction.

Table 2.1. CMECS Settings and Components. AS, BS, BC, and SC are internally 

hierarchical. WC and GC include non-hierarchical subcomponents.

2.2.1 Water Column Component (WC)

The WC represents a new approach to the ecological classification of open water settings. 

The component describes the water column in terms of vertical layering, water 

temperature and salinity conditions, hydroforms, and biogeochemical features. Modifiers 

allow users to further subdivide water column units. Representative units include “cold, 

oligohaline estuarine open water surface layer” and “warm marine offshore western 

boundary current oceanic epipelagic upper layer.” See Section 5 for more details.

2.2.2 Geoform Component (GC) 

The GC describes the major geomorphic and structural characteristics of the coast and 

seafloor. This component is divided into four subcomponents that describe tectonic and 

physiographic settings and two levels of geoform elements that include geological, 

biogenic, and anthropogenic geoform features. Representative units include lagoon, 

ledge, tidal channel/creek, and moraine. See Section 6 for more details.

2.2.3 Substrate Component (SC)

The SC describes the composition and size of estuary bottom and sea bed materials in all 

CMECS systems. This component is hierarchical and encompasses substrates of 
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geologic, biogenic, and anthropogenic origin. Particle size classes conform to those 

developed by Wentworth (1922) and substrate mixes conform to the standard described 

by Folk (1954). Representative units include sandy mud, coral sand, and construction 

rubble. See Section 7 for more details.

2.2.4 Biotic Component (BC)

The BC is a hierarchical classification that identifies (a) the composition of floating and

suspended biota and (b) the biological composition of coastal and marine benthos. 

Representative units include Sargassum raft, jellyfish aggregation, Oculina reef, 

Crassostrea bed, and Rhizophora mangle fringe forest. Units are compatible with terms 

used in FGDC-STD-004 (FGDC 1996b) and FGDC-STD-005-2008 (FGDC 2008). See 

Section 8 for more details.

2.3 Biotopes

A biotope is defined as the combination of abiotic features and associated species 

(Connor et al., 2003). Using CMECS, biotopes can be derived by identifying repeating 

BC biotic communities that are consistently associated with combinations of 

environmental units from any of the other CMECS settings or components (Figure 2.2). 

While individual biotope units have not been defined yet, users can begin to define and 

describe biotopes as they apply CMECS. As knowledge of biotopes increases, biotope 

units and descriptions will be added to CMECS. See Section 9 for more details.

2.4 Modifiers

CMECS incorporates a list of standard modifiers―a consistent set of characteristics and 

definitions— as part of each component to describe the nature and extent of observed 

variability within ecological units (Figure 2.2). Modifiers allow users to customize the 

application of the classification in a standardized manner. See Section 10 for more 

details.
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Figure 2.2. Relationship between CMECS Settings, Components, Modifiers and 

Biotopes.

2.5 Using the Components

Each CMECS component is autonomous (i.e., designed to be classified and mapped 

independently of the others), but components can be combined as necessary, depending 

on application. This is analogous to combining information from independent land cover, 

landform, and soil classifications (in terrestrial classifications) to describe specific 

locations on land. 

For example, a CMECS user requiring an inventory of seagrass distribution might 

categorize and map biological units using the BC to arrive at estimates of total seagrass 

acreage or coverage by a single species. Users interested in mapping benthic cover by 

conventional means (i.e., via downward-looking sensors) would use the SC and the BC 

together. However, users concerned with the global distribution of seamounts would 

focus on the GC instead. Those users with interest in the zonation of biotic communities 

on seamounts might overlay the BC on the GC, to provide insight into how patterns in the 

biology vary with geologic structure.
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CMECS allows users to examine relationships between biotic and abiotic features and 

processes in different ecological units at comparable scales. This can be done 

qualitatively (using the scales implied within the components) and quantitatively (either 

by creating maps of ecological units or by using spatial and temporal modifiers).

The aim of modifiers is to better characterize relationships among multi-scale 

quantitative ecological data, natural variability, and human influence in order to provide 

the best information for effective management and assessment of these ecosystems 

(Guarinello, Shumchenia, and King 2010). For example, spatial modifiers help relate the 

geographic extent of features to one another—especially when mapping or geographic 

information system (GIS) tools are not a part of the classification effort. Temporal 

modifiers help distinguish features based on expected temporal persistence or variability.

While the natural inclination of many users may be to apply CMECS from the “topdown”—from the broadest elements of the classification to increasingly narrow (i.e., 

more precise) elements—the system works equally well when applied from the “bottomup.” Such analyses may involve one or more components and permit examinations such 

as those evaluating factors influencing the occurrence or success/failure of biotic

assemblages in space and time. 

The CMECS components enable the development of sophisticated analyses of physical, 

chemical, and biological information—and they permit users to explore complex 

ecological interactions. The application and combination of components is further 

discussed in Section 12.

2.6 Ecological Foundation

The goal of CMECS is matching specific aspects of the physical environment—defined

in ecological units—to organisms and biological associations that use the environment.

Physical, geological, and chemical characteristics of the environment interact with the 

requirements and behaviors of organisms to create the patterns of life observed in benthic 

and water column settings. In turn, patterns of environmental stresses and drivers, 

resource utilization, nutrient transformation, reproduction, population dynamics, and 

community structure reflect the availability of habitat in time and space (Cushing 1990). 

Many of these processes are not uniformly applicable across all aspects of CMECS, and 

some may conflict at different scales. The multiple-component structure of CMECS is 

designed to accommodate for both of these concerns. 

CMECS addresses the full range of natural processes—from short to long timescales. 

Drivers of ecological interactions operate at specific frequencies to which the biota is 

matched (Ulanowicz 1996), and life cycles and behavior are tuned to temporal and 

resource patterns to optimize resource use, survival, and recruitment. Multiple scales of 

energy, temperature, light, and resource sufficiency are captured in the CMECS structure. 

Many processes are hierarchical, in that a larger-scale process drives or influences 

smaller-scale, internal processes. Identifying those drivers that organize the geo-physical 
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environment (and the organisms that inhabit it) is a significant challenge facing CMECS

(Pahl-Wostl and Ulanowicz 1993).

2.6.1 Temporal and Spatial Variation

Units that experience change over time can be described by repeated assessment. 

Individual CMECS characterizations represent snapshots of the state of ecosystem units 

at given points in time. Temporal variability or change may be examined by comparing 

time series of individual characterizations. In the same way that animation achieves a 

sense of movement by juxtaposing a succession of individual illustrations, studying 

multiple, successive characterizations of CMECS ecological units demonstrates the 

nature and rate of changes occurring on (or within) a unit of substrate or the water

column. Because analytical contexts are determined by the observer—and are dictated in 

part by the scope of the available data and the nature of analytical techniques at hand, 

CMECS may be considered temporally neutral, accommodating with equal facility

variation ranging from short term (fractions of seconds to hours) to long term (years to 

centuries).

The wide range of spatial and temporal scales in marine and coastal systems is a 

challenge for ecological classification, because measuring tools capture only portions of 

the space-time continuum. CMECS integrates components of large- and small-scale 

geologic, biotic, water column, and sediment-related processes within a common 

hierarchical framework. Analyses of species-environment relationships can be structured 

to use time, spatial replication, or spatial contrast as the basis for experimentation and 

hypothesis testing (Murawski et al. 2010). Because spatial and temporal scales are linked, 

complex ecosystems can be deconstructed and understood in space and time 

simultaneously (Wu 1999). A further discussion of time and space considerations in the 

context of CMECS is presented in Section 11.

2.6.2 Nature of CMECS Units

CMECS provides a standardized framework for naming ecological units in coastal and 

marine settings. Units are conceptual and circumscribed by defined conceptual 

boundaries based on consensus best professional judgment and observations by the 

community of practice. Unit definitions include a limited degree of variation consistent 

with what is observed in nature across the range of occurrence. Ideally, over time, the 

conceptual boundaries that delimit CMECS units will be based on analysis of data 

collected across the range of each unit.

Assemblages classified by CMECS as ecological units occur multiple times in nature. 

Contrary to animal and plant taxonomy where a species may be described on the basis of 

a single specimen, CMECS units reflect recurring observations in space and time. 

Similarly, the occurrence of a single specimen with a unit of the ecosystem is insufficient 

to characterize that unit. Evidence of an aggregation or assemblage that repeats on the 

seafloor (or in the water column), the presence of dominant or representative species, or 
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the occurrence of characteristic geological, chemical, or physical attributes is required 

before units can be classified. A photo of a single sea cucumber is insufficient to 

characterize a holothurian biotic community.

CMECS provides a systematic approach for classifying continuously-varying, 

multidimensional assemblages. Ecological units often span physical, chemical, or 

geological gradients in space or time; the units may transition gradually or sharply,

depending on the abruptness of the determining feature (Gleason 1926; Curtis 1959; 

Whittaker 1962). Classification frameworks impose boundaries across gradients to define 

units, under the assumption it is reasonable and useful to separate a continuum into 

meaningful units (Whittaker 1975; McIntosh 1993). Units based on “natural breaks” 

generally are more easily applied and are of greater utility. 

In cases where no discontinuities occur and there is strong reason to favor differentiation, 

boundaries may reflect consensus professional opinion about meaningful breakpoints or 

non-environmental realities such as analytical or measurement limitations. CMECS 

provides a systematic approach for classifying continuously-varying, multi-dimensional 

assemblages. As a result, CMECS units are largely homogeneous in composition or 

structure, recognizing limited natural variability or a limitation in an analytical 

approach’s ability to discern differences within a unit. 

CMECS units are spatial tessellations, defined on the basis of attributes observed in 

specific areas of the seafloor (as viewed from above) or specific segments of the water 

column (in three-dimensional space). As such, definitions of benthic BC units generally 

note that the area is dominated by a particular organism, to indicate the units are 

representations of the organisms on a specific area of the bottom. For each component, 

one patch of seafloor (or one segment of the water column) corresponds to one CMECS 

unit.

CMECS units are not constrained to specific observational approaches (e.g., satellite 

imagery, benthic grab samples) or specific sample areas or volumes (e.g., 1- meter square 

quadrats). CMECS units are scale-independent; they can be fitted to the requirements of 

individual studies. 

CMECS encompasses both natural and anthropogenic features. Humans impact the 

seascape for good and for bad; these influences shape the seafloor and affect conditions 

in the water column. The inclusion of anthropogenic features within CMECS allows the 

classification of all environmental components presently found in nature.
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3. Biogeographic Setting

The composition and characteristics of biological communities vary with latitude and 

longitude and are functions of factors including climate, geological setting and 

evolutionary history. Variation across time and space of elements such as temperature, 

insulation, water and food availability, degree of isolation, and presence of suitable 

habitat affect the abundance, activity, reproductive capacity, and ecological 

competitiveness of individual species. This, in turn, produces changes in species 

dominance, food-web complexity, and the functioning of regional and local ecosystems.

Over the past century and a half, considerable effort has been invested in describing and 

deciphering the factors responsible for observed geographic patterns in animal and plant 

community distributions. Notable successes have been achieved for terrestrial and 

freshwater settings (Bailey et al. 1994, Omernik 1995, Keys et al. 1995, EPA 2001, 

Cleland et al. 2005, Abell et al. 2008), and valuable regional and local characterizations 

have been produced for estuarine and nearshore coastal settings. However, 

comprehensive national and international biogeographic assessments for marine systems 

have been lacking until recently (e.g., see Wilkinson et al. 2009, pp. 5-7). CMECS draws 

from some of the most recent publications and divides the Biogeographic Setting into 

three hierarchical categories (Table 3.1). 

Table 3.1. Biogeographic Setting Classification Structure.

Biogeographic Setting

Realm

 Province

 Ecoregion

3.1 Biogeographic Units--Estuarine System and Marine 

Nearshore and Offshore Subsystems

In 2007, Spalding et al. proposed a new approach for characterizing bioregions of marine 

coastal and shelf environments. The Marine Ecoregions of the World (MEOW) technique 

affords global coverage and creates a nested, three-tiered system of realms, provinces, 

and ecoregions (moving from larger-scale to smaller-scale units). The classification 

builds upon existing global and regional literature, and the classification has achieved 

significant acceptance—especially within the international community. Water column 

and benthic environments are addressed in the classification, and it deals with all waters 

under U.S. jurisdiction, including those adjacent to U.S. commonwealths and territories. 

CMECS proposes to use the MEOW realms, provinces, and ecoregions for describing 

biogeographic elements of the Estuarine System and the Marine Nearshore and Offshore 

Subsystems. The following definitions of these descriptors are from page 575 (Spalding 

et al. 2007):
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 Realms: “Very large regions of coastal, benthic, or pelagic ocean across which 

biota are internally coherent at higher taxonomic levels, as a result of a shared and 

unique evolutionary history. Realms have high levels of endemism, including 

unique taxa at generic and family levels in some groups. Driving factors behind 

the development of such unique biota include water temperature, historical and 

broad scale isolation, and the proximity of the benthos.” Examples include Arctic, 

Temperate Northern Pacific, and Tropical Atlantic.

 Provinces: “Large areas defined by the presence of distinct biota that have 

at least some cohesion over evolutionary time frames. Provinces will hold 

some level of endemism, principally at the level of species. Although 

historical isolation will play a role, many of these distinct biota have 

arisen as a result of distinctive abiotic features that circumscribe their 

boundaries. These may include geomorphological features (isolated island 

and shelf systems, semi-enclosed seas); hydrographic features (currents, 

upwellings, ice dynamics); or geochemical influences (broadest-scale 

elements of nutrient supply and salinity).” Examples include Cold 

Temperate Northeast Pacific, Tropical Northwestern Atlantic, and Cold 

Temperate Northeast Pacific.

 Ecoregions: “Areas of relatively homogeneous species composition, 

clearly distinct from adjacent systems. The species composition is likely to 

be determined by the predominance of a small number of ecosystems 

and/or a distinct suite of oceanographic or topographic features. The 

dominant biogeographic forcing agents defining the eco-regions vary from 

location to location but may include isolation, upwelling, nutrient inputs, 

freshwater influx, temperature regimes, ice regimes, exposure, sediments, 

currents, and bathymetric or coastal complexity.” Examples include 

Virginian, Northern Californian, and Eastern Caribbean.

Figure 3.1 illustrates the global distribution of MEOW realms, provinces, and ecoregions. 

Appendix B lists the MEOW units impinging upon U.S. waters.

3.2 Biogeographic Units--Marine Oceanic Subsystem

MEOW coverage does not extend much beyond the edge of the U.S. Exclusive Economic 

Zone (Spalding et al. 1997). However, the principles guiding the MEOW approach were 

applied to oceanic benthic and water column settings and published as the Global Open 

Oceans and Deep Seabed Biogeographic Classification (GOODS) by scientists working 

under the aegis of UNESCO (United Nations Educational, Scientific and Cultural 

Organization)(UNESCO 2009).
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Figure 3.1. MEOW Realms, Provinces, and Ecoregions.

At top (a), biogeographic realms with ecoregion boundaries outlined; at bottom (b), 

provinces with ecoregions outlined (from Spalding et al. 2007, 577).

As in MEOW, GOODS partitions the marine system into realms, provinces, and 

ecoregions; however, separate units are defined for benthic and water column settings. 

Figure 3.2 illustrates the pelagic provinces proposed in GOODS, and Figures 3.3 and 3.4 

depict the lower bathyl and abyssal provinces identified in GOODS. GOODS remains 

under development and refinements are expected over time. However, the biogeographic 

units are sufficiently well-defined for application as part of the CMECS Biogeographic 

Settings.
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Figure 3.2. Pelagic Biogeographic Provinces Identified in GOODS 

(UNESCO 2009).

Figure 3.3. Lower Bathyl Benthic Biogeographic Provinces Proposed in GOODS 

(UNESCO 2009).
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Figure 3.4. Abyssal Benthic Biogeographic Provinces Proposed in GOODS 

(UNESCO 2009).

3.3 Biogeographic Units--Lacustrine System (Great Lakes)

MEOW does not extend inland to include freshwater systems; however, a rich heritage of

biogeographic study exists for the Great Lakes. CMECS proposes the approach taken by 

Abell et al. (2008) as an interim means for defining biogeographic units in the Great 

Lakes. A more definitive treatment of biogeographic units for the Great Lakes will be 

developed under the dynamic standard provisions of CMECS. 
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4. Aquatic Setting

The Aquatic Setting (AS) is comprised of three hierarchical levels (System, Subsystem 

and Tidal Zone) and provides the context for all CMECS components. It distinguishes 

oceans, estuaries and lakes, deep and shallow waters and submerged and intertidal 

environments within which more refined classification of geological, physicochemical, 

and biological information can be organized.

Table 4.1. Aquatic Setting Classification Structure.

Aquatic Setting

System

 Subsystem

 Tidal Zone

4.1 Aquatic Setting Hierarchical Structure

4.1.1 System

The CMECS Systems—Lacustrine, Estuarine, and Marine—are based on salinity and 

geomorphological characteristics of the setting. System (as defined in CMECS) is 

equivalent in concept to system as defined in Classification of Wetlands and Deepwater 

Habitats in the United States, FGDC-STD-004 (FGDC 1996b). The definition and units 

of the Lacustrine System are similar to the analogous system of FGDC-STD-004. The 

Great Lakes are classified as a Lacustrine System in CMECS and coincide with the 

definitions and concepts of FGDC-STD-004. The Estuarine System has basic similarity 

with FGDC-STD-004, but includes the tidal freshwater portion of the Riverine System as 

defined in FGDC-STD-004. This is done to unify the tidal fresh and low-salinity portions 

of estuaries within the CMECS Estuarine System umbrella. The Marine System has been 

elaborated significantly in CMECS, to include the ocean environments and habitats. 

4.1.2 Subsystem

Each system is divided into subsystems based on depth and position relative to the 

shoreline. Lacustrine Systems include the Subsystems Littoral and Limnetic, conforming, 

respectively to shoreline and deepwater habitats. The Estuarine System has four 

Subsystems: Coastal, Open Water, Tidal Riverine Coastal and Tidal Riverine Open 

Water. The Marine System is comprised of three Subsystems: Nearshore, Offshore, and 

Oceanic, distinguished by total water depth. 
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4.1.3 Tidal Zone

Tidal zone is an important determinant of biological and abiotic processes in the 

environment. Habitats in the littoral zone support life forms that can tolerate the 

sometimes highly energetic physical processes of tide, wave and current action. Biota in 

these areas are also subjected to alternate submergence and drying/desiccation. 

Temperatures in littoral and intertidal habitats are more extreme than in the buffered 

subaqueous environment, and excessive light and radiant energy can present a challenge 

for some biota. Evaporation, drying and concentration of salts creates sometimes harsh 

conditions for vegetation and fauna at the land-sea margin and the high energy of coastal 

situations increases erosional depositional forces. 

Subtidal environments are presented with a different set of challenges in that oxygen, 

light, nutrients and temperature are often reduced with respect to biological requirements 

and species and communities have developed characteristic strategies to optimize access 

to resources in these environments. In CMECS each Subsystem in the Estuarine and 

Marine System is distinguished by tidal zone (Figure 4.1). 

4.2 Aquatic Setting Units

4.2.1 Lacustrine System

The CMECS Lacustrine System includes (a) all deepwater areas of the Great Lakes and 

(b) shoreline areas of the Great Lakes with less than 30 percent areal coverage by trees, 

shrubs, and persistent emergents. In areas with a greater percentage of vegetative cover, 

the appropriate Palustrine FGDC-STD-004 should be used for classification. Where a 

river enters or leaves a lake, the extension of the lacustrine shoreline forms the riverinelacustrine boundary.

 Subsystem: Lacustrine Littoral – The Littoral Subsystem includes shallow 

habitats in the Lacustrine System. The shoreward boundary of this subsystem 

extends to the landward limit of non-persistent emergents. The lakeward 

boundary includes all waters to a depth of 2 meters below Mean Lower Low 

Water (MLLW), or to the maximum extent of non-persistent emergents, 

whichever depth is greater.

 Subsystem: Lacustrine Limnetic – The Limnetic Subsystem includes all 

deepwater habitats within the Lacustrine System. “Deepwater habitats” are 

those that occur at depths greater than 2 meters below MLLW—unless there 

are non-persistent emergents in those areas. In which case, “deepwater habits” 

are those beyond the limit of occurrence of non-persistent emergents.
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Figure 4.1. Aquatic Setting Hierarchy Showing System, Subsystem and Tidal Zone.

4.2.2 Estuarine System

The Estuarine System is defined by salinity and geomorphology. This System includes 

tidally influenced waters that (a) have an open-surface connection to the sea, (b) are 

regularly diluted by freshwater runoff from land, and (c) exhibit some degree of land 

enclosure. 
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The Estuarine System extends upstream to the head of tide and seaward to the mouth of 

the estuary. Head of tide is identified in accordance with the Metadata Profile for 

Shoreline Data, FGDC-STD-001.2-2001 (FGDC 2001) as the inland or upstream limit of 

water affected by a tide of at least 0.2 foot (0.06 meter) amplitude. The mouth of the 

estuary is defined by an imaginary line connecting the seaward-most points of land that 

enclose the estuarine water mass at MLLW. Islands are included as headlands if they 

contribute significantly to the enclosure.

Estuaries occur on continents or on islands and include waters of any depth. In CMECS 

they are defined as waters bounded by significant enclosure by land, having a direct 

connection to the sea and receiving measurable freshwater input to some part of the 

enclosed system during an average year. Salinity, a dimensionless conductivity ratio as 

measured on the practical salinity scale (PSS), was established by the IAPSO 

(International Association for the Physical Sciences of the Oceans) in 1978 (UNESCO 

1981), and is of prime importance in distinguishing freshwater from saline estuarine 

environments and differentiating among estuarine and marine environments of differing 

salinity. The range of salinity considered in the CMECS classification extends from zero 

to hyperhaline (>40). Oceanic salinities normally encountered throughout the world 

range from 30-40 on the PSS scale. Highly saline negative estuaries such as Laguna 

Madre and Florida Bay may experience salinity as high as 70-80. Extreme environments 

like the Dead Sea have salinity near 300. 

The tidally influenced part of the estuary may occur in a fresh reach where salinity is 

<0.5. According to FGDC-STD-004, this area would be classified within the Riverine 

System. However in CMECS, the Tidal Riverine area is considered to be an integral part 

of the ecology of the estuarine ecosystem, so it is classified within the Estuarine System 

instead. 

The Estuarine System has four subsystems: Coastal, Open Water, Tidal Riverine Coastal, 

and Tidal Riverine Open Water.

 Subsystem: Estuarine Coastal – The Estuarine Coastal Subsystem extends 

from the supratidal zone at the land margin up to the 4 meter depth contour in 

waters that have salinity greater than 0.5 (during the period of average annual 

low flow). The Estuarine Coastal Subsystem would be considered the shallow 

perimeter in a deeper estuary, although many estuaries may be entirely less 

than 4 meters deep and be classified as completely in the Coastal Subsystem. 

The 4 meter contour was selected as a cutoff between “coastal” and “offshore” 

estuarine waters because it identifies (somewhat arbitrarily) a region that is 

both shallow and generally in close proximity to the shore, making the 

substrate-to-water volume ratio here the highest in the entire estuary. A 

convening of experts delineated this 4 meter contour as described in Reilly, 

Spagnolo, and Ambrogio (1999) as important in both an ecological and a 

regulatory sense in estuarine systems and CMECS has adopted it to emphasize 

the significant human and natural processes that occur there.
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The high wetland-water ration and pelagic-benthic connectivity makes the 

Estuarine Coastal Subsystem an extremely dynamic and active area in terms 

of hydrodynamics, geology, and biology. It is this area in shallow coastal 

waters where maximum interaction between estuarine waters, and adjacent 

wetlands or developed shoreline occurs and often where intense juxtaposition

of human activity and the natural system occurs. Watershed, point and nonpoint inputs to the estuary are often maximal in this shallow zone. 

Because the Coastal Subsystem tends to receive an abundance of light, these 

waters and bottom areas are usually sites of high primary production. In water 

columns, shallow waters typically support high phytoplankton productivity 

while shallow water bottoms are covered in highly productive 

microphytobenthos, macroalgae and/or rooted macrophytes and their attached 

epiphytic communities. As regions of high primary production, shallow 

waters attract an abundance of higher trophic level organisms that feed on 

plants and on their grazer communities. Strong physical subsidies from 

flowing waters and wind stresses create waves and currents that generally 

maintain the shallow waters in a well-oxidized state. Surface waters of the 

Coastal Subsystem tend to be well-mixed and are affected by strong physical 

processes that impact the bottom: resuspending sediments, reducing light and 

altering spectral characteristics of the light climate. The estuarine bottom in 

shallow waters is also subject to frequent wind-induced reworking and 

transport of sediments and dynamic bedforms. 

The Estuarine Coastal Subsystem is divided in three zones based on tidal action:

o Tidal Zone: Estuarine Coastal Subtidal – The substrate is 

generally continuously submerged in this zone and includes those 

areas below MLLW.

o Tidal Zone: Estuarine Coastal Intertidal – The substrate in this 

zone is regularly and periodically exposed and flooded by tides. 

This zone extends from MLLW to Mean Higher High Water 

(MHHW). The Coastal Intertidal is exposed regularly to the air by 

tidal action. 

o Tidal Zone: Estuarine Coastal Supratidal – This zone includes 

areas above MHHW; areas in this zone are affected by wave splash 

and overwash. It does not include areas affected only by winddriven spray, which may extend further inland.

 Subsystem: Estuarine Open Water – The Estuarine Open Water Subsystem 

includes all waters of the Estuarine System with a total depth greater than 4 

meters, exclusive of those waters designated Tidal Riverine Open Water. 
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The Open Water Subsystem is subject to a number of physical factors that 

make it distinct from the Coastal Subsystem, including reduced air-water 

exchange, potentially reduced light at depth, reduced physical impact from 

waves and surface currents and reduced interaction between the water column 

and the bottom. Moreover, because of the formation of stratified layers in the 

Estuarine System, the Open Water Subsystem is often “capped” by a 

relatively strong density or stability gradient that distinctly separates the lower 

water column from the upper water column, separated by a zone of transition 

(such as a pycnocline, halocline, or thermocline). 

The Open Water Subsystem may be heterotrophic, because it often acts as a 

receiving basin for organic material settling from the shallower, better lit

surface waters, especially when the waters are stratified and form shallow 

flanks of the water body. At times, this role as a heterotrophic zone may 

support high rates of respiration (relative to production) and therefore 

consume much of the available oxygen and lead to the formation of hypoxic 

or anoxic zones, generally in the deeper parts of these waters. Additionally, 

stratification and the mechanics of estuarine circulation often promote the 

formation of a salt wedge intrusion (from the marine environment) that 

renders the bottom waters more saline than waters in the surface layer above. 

o Tidal Zone: Estuarine Open Water Subtidal – The substrate is 

generally continuously submerged in this zone and includes those 

areas below MLLW.

 Subsystem: Estuarine Tidal Riverine Coastal – The Estuarine Tidal 

Riverine Coastal Subsystem includes the most upstream region of the estuary, 

in those areas between MHHW to the 4 meter depth contour below MLLW in 

waters that (a) can be regularly influenced by tides and (b) where salinity is 

below 0.5 during the period of annual low flow. The areas with this salinity 

may extend upriver to the head of tide, which is identified as the point where 

the mean tidal range becomes less than 0.2 feet (0.06 meters) (FGDC 2001).

The Tidal Riverine Coastal Subsystem includes upstream areas that are 

influenced by ocean tides, but do not experience significant salinity. The 

hydraulic gradient is low and water stage and velocity fluctuate under tidal 

influence. Water is always present and is confined within a channel, and is 

usually flowing. The Tidal Riverine Coastal Subsystem is a critical part of the 

ecology and habitat of the estuary. This area is the site of significant 

ecological activity and a number of estuarine and coastal species depend on 

Tidal Riverine Coastal areas for breeding habitats, nursery habitats, and 

migratory pathways (e.g., striped bass, wading birds, and anadromous fishes). 

The Tidal Riverine Coastal Subsystem also supports unique hydrological 

features, for example the Estuarine Turbidity Maximum, tidal bores and 

Coriolis deflections.
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o Tidal Zone: Estuarine Tidal Riverine Coastal Subtidal – The 

substrate is generally continuously submerged in this zone and 

includes those areas below MLLW.

o Tidal Zone: Estuarine Tidal Riverine Coastal Intertidal – The 

substrate in this zone is regularly and periodically exposed and flooded 

by tides. This zone extends from MLLW to the extent of tidal 

inundation, i.e., the extreme high water of spring tides. The Coastal

Intertidal is exposed regularly to the air by tidal action. 

 Subsystem: Estuarine Tidal Riverine Open Water – The Estuarine Tidal 

Riverine Open Water Subsystem includes tidal freshwater areas with a salinity 

of <0.5 and a depth of greater than 4 meters at MLLW.

The Estuarine Tidal Riverine Open Water Subsystem is the most upstream 

portion of the estuary and subject to river and watershed influences, including 

high nutrient and sediment loads and low salinity. Similar to the Estuarine 

Open Water Subsystem, physical impact from waves and surface currents is 

reduced interaction at depth. This zone may be the site of the upper limit of 

the salt wedge and of a turbidity maximum zone, important as feeding and 

aggregation sites for plankton and benthic species. This zone is also 

potentially subject to high organic loading and formation of hypoxic waters. 

Primary production is often low, due to high turbidity and deep, dimly lighted 

water columns, especially in the river channel. For this reason, the Tidal 

Riverine Open Water Subsystem may be heterotrophic with net negative 

metabolic rates. 

o Tidal Zone: Estuarine Tidal Riverine Open Water Subtidal – The 

substrate is generally continuously submerged in this zone and 

includes those areas below MLLW.

4.2.3 Marine System

The Marine System is defined by salinity, which is typically about 35, although salinity 

can measure as low as 0.5 during the period of average annual low flow near fresh 

outflows. This system has little or no significant dilution from fresh water except near the 

mouths of estuaries and rivers. The Marine System includes all non-estuarine waters from 

the coastline to the central oceans. The landward boundary of this system is either the 

linear boundary across the mouth of an estuary or the limit of the supratidal splash zone 

affected by breaking waves. Seaward, the Marine System includes all ocean waters.

The Marine System is typified by waves, currents and coastal water regimes determined 

by oceanic tides. Coastal indentations and bays that do not receive appreciable and 

regular freshwater inflow are part of the Marine System. Areas where river plumes 

discharge directly into marine waters without geomorphological enclosure are also part of 
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the Marine System. In such areas, (e.g., Mississippi River plume, Chesapeake Bay

plume), low salinity water and fresh plumes may discharge from the seaward boundary of 

the estuary, extending far into the Marine System beyond the enclosed part of the estuary. 

These freshwater features are considered to be Hydroforms within the Marine System

(see Section 5).

The Marine System has three subsystems (which are defined by depth): Nearshore, 

Offshore, and Oceanic.

 Subsystem: Marine Nearshore – The Marine Nearshore Subsystem extends 

from the landward limit of the Marine System to the 30 meter depth contour.

The 30 meter depth contour was selected as a useful cutoff between shallower 

nearshore and deeper offshore waters. It is intended to represent an 

ecologically significant depth to which water column and benthic processes 

are strongly coupled in the Nearshore Subsystem. Surface currents and waves 

impinge the bottom at the storm wave base (Keen and Holland 2010) and 

vertical circulation generally distributes nutrients and sediments throughout 

the water column. The photic zone extends through the entire water column

except in extreme cases (Kleypas, McManus and Menez 1999). The presence

of nutrients and light support the growth of vegetation on the bottom including

seagrass and macroalgal beds and 30 meters generally represents the depth to 

which most living coral is found.

o Tidal Zone: Marine Nearshore Subtidal – The substrate is generally 

continuously submerged in this zone and includes those areas below 

MLLW.

o Tidal Zone: Marine Nearshore Intertidal – The substrate is 

regularly and periodically exposed and flooded by tidal action. This 

zone extends from MLLW to MHHW. 

o Tidal Zone: Marine Nearshore Supratidal – This zone includes 

areas above MHHW that are affected by wave splash and overwash 

but does not include areas affected only by wind-driven spray. This 

zone is subjected to periodic high wave energy, exposure to air, and 

often to variable salinity.

 Subsystem: Marine Offshore – The Marine Offshore Subsystem extends 

from the 30 meter depth contour to the continental shelf break, as defined by 

the maximum slope discontinuity with a rapid change in gradient of 3° or 

greater at the outer edge of the continental shelf. This shelf break boundary 

generally occurs between 100 - 200 meters depth. In the case of steep-sided, 

oceanic islands, where a continental shelf is not present, the offshore 

boundary of the Offshore Subsystem is defined at a bottom slope discontinuity 

occurring between 100-200 meters, or at 200 meters if no such discontinuity 

exists. 
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The waters and benthos of the Offshore Subsystem are less coupled to each 

other and typically less influenced by terrigenous processes than in the 

Nearshore Subsystem. Distance from shore can vary greatly, depending on 

shelf morphology, and waters at the 30 meter isobath can be quite distant from 

the shore or may lie relatively close to land. 

The Offshore Subsystem may be strongly influenced by open-ocean 

biogeochemistry and physical processes. Often distinct water layers at the 

surface and bottom may be present. Because Offshore Subsystem waters are 

less influenced by coastal inputs, they generally are less turbid than those of 

the Nearshore Subsystem. Light penetration in the Offshore Subsystem can 

extend to significant depths and often reach the ocean bottom.

o Tidal Zone: Marine Offshore Subtidal – The substrate is 

subtidal and continuously submerged in this zone and includes 

those areas below MLLW.

 Subsystem: Marine Oceanic – The Marine Oceanic Subsystem represents 

the open ocean, extending from the continental shelf break to the deep ocean. 

Oceanic waters typically have salinity levels of ≥ 36. Water depths typically 

range from 100 - 200 meters at their shallowest at the shelf break to over 

11,000 meters at the deepest point in the ocean. 

The great depth of the Oceanic Subsystem is responsible for many of its 

characteristics. The oceanic water column tends to be more stable

physicochemically; undergoing changes in temperature and salinity relatively 

slowly. Greater depth also diminishes the influence of the sea bottom on the 

overlying water column. Surface and bottom processes generally are poorly 

coupled and separated by great distances and thermocline layers. The waters 

of the Oceanic Subsystem receive little direct terrigenous input; the inputs 

from land typically occur indirectly, after passage through the substantial 

coastal water masses or atmospheric deposition.

Conditions in the Oceanic Subsystem are a function of the properties of the 

water column. For example, light penetration diminishes with depth (as sea 

water absorbs component wavelengths); thus, the quality and intensity of 

ambient light changes with depth. Little surface light penetrates below the 

photic zone (~200 meters). At greater depths, light is limited to that produced 

locally by bioluminescence. Water pressure also increases directly with depth 

because of the weight of the overlying water column, and water temperatures 

diminish with depth. 

o Tidal Zone: Marine Oceanic Subtidal – The substrate is subtidal 

and continuously submerged in this zone.
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5. Water Column Component

The Water Column Component (WC) describes the water column environment of 

estuaries and oceans.The water column presents unique challenges to classification and 

characterization—due to its three-dimensional structure; a high degree of temporal 

variability; a wide, dynamic range in environmental characteristics (across multiple 

spatial scales); and the inherent challenges of measuring the various parameters. The WC

identifies the structures, patterns, properties, and processes, of the water column relevant 

to ecological relationships and habitat-organism interactions. This component extends 

from the land-sea margin to the deep oceans and vertically from the surface of the water 

to the benthic interface. The WC encompasses the Lacustrine, Estuarine, and Marine 

Systems. The water column component of the Lacustrine System will be fully addressed 

in a later document, while the latter two systems are described here.

Because the water column is highly variable in both time and space, it is difficult to 

assign structures or properties to a specific location or depth with certainty. The 

characteristics of the water continuously change over time. For example, in the clear 

waters of the open ocean, the well-lit zone of photosynthesis generally extends 

throughout the upper 200 meters of the water column. In estuaries and coastal waters, 

surface conditions and water constituents reduce the depth of the photic zone by orders of 

magnitude. Nearshore photic depths can be quite shallow and variable from place to place 

or over short time periods. In shallow waters, optical dynamics are compressed in the 

vertical dimension and their effects are amplified—strongly influencing biota in the water 

column and in the benthos.

The WC is designed to accommodate the high degree of spatio-temporal variability of the 

water column with a simple and flexible structure and a comprehensive array of units and 

modifiers. The WC provides a way to define and organize key information most 

commonly required to characterize the water column. Spatially, the WC can be applied to 

points or profiles within the water column, as well as to water masses, regions, entire 

water bodies and entire oceans.

The WC contains five subcomponents that can be used alone or in combination (Table 

5.1): Layer, Salinity, Temperature, Hydroform and Biogeochemical Feature. The Layer 

subcomponent indicates vertical position within the water column, using a set of defined 

layers associated with each subsystem and gives information about relative proximity to 

the atmosphere, mid-depth or benthos. Units in the Salinity and Temperature 

subcomponents describe the salinity and temperature characteristics of a water parcel 

within standard ranges. Hydroform Classes, their hydroforms, and hydroform types 

describe physical hydrographic features such as currents, waves, water masses, gyres,

upwellings and fronts. The Biogeochemical Features subcomponent describes such 

phenomena as biofilm, thermocline and turbidity maximum—features of the water 

column that include properties and constituents beyond simple hydrodynamics. Modifiers 

can be selected from a comprehensive list and applied to any component to define 
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additional characteristics such as trophic status, oxygen status, tide regime and energy 

regime.

Table 5.1. Water Column Classification Structure.

Water Column Component

Layer 

Subcomponent

Salinity 

Subcomponent

Temperature 

Subcomponent

Hydroform 

Subcomponent

Biogeochemical 

Feature 

Subcomponent

List of layers List of salinity 

ranges

List of 

temperature 

ranges

 Hydroform Class

 Hydroform

 Hydroform Type

List of 

biogeochemical 

features

5.1 Water Column Layers

The Water Column Layer Subcomponent resolves the water column vertically into its 

major coherent layers based on position relative to the surface and to the pycnocline or 

mid-depth. These layers reflect ecologically important characteristics of the water column 

structure. The layers for all cross-shelf waters include Surface Layer, Upper Water 

Column, Pycnocline and Lower Water Column. In the Marine Oceanic Subsystem, 

additional divisions (described below) are based on depth in the water column. The Layer 

subcomponent works with the Subsystem of the Aquatic Setting described in Section 4 to 

define the estuarine and marine water column as a grid. The grid framework is composed 

of horizontal regions (x-y axes) divided on the basis of position relative to land and total 

water depth, and vertical layers (z-axis) defined by depth below the surface. This 

structural arrangement provides a fixed frame of reference for describing position within 

the water column and accommodates the variability in water column features, conditions 

and movements by applying additional subcomponents (Figure 5.1).

One set of Water Column Layers is defined for application to all Estuarine Subsystems 

and the two Marine Subsystems (Nearshore and Offshore) in cross shelf waters where the 

total water depth is relatively shallow.

For all subsystems (except the Marine Oceanic) the following Water Column Layers are 

defined:

 Surface Layer: The interface between the water column and the atmosphere, 

extending to a depth of several centimeters, represents the surface of maximum 

exchange of atmospheric gases, heat and light. Surface films, floating vegetation

and aggregations of materials or biota accumulate at this interface.

 Upper Water Column: The area from just below the surface to the boundary of 

the pycnocline, if present. (If a pycnocline is not present or is not detected, the 
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region above mid-depth in the water column is defined as the Upper Water 

Column.) The upper water column layer is in close contact with the atmosphere;

usually oxygenated, well-mixed and well-lighted; and is generally marked by high 

rates of photosynthesis and net autotrophic production.

 Pycnocline: The zone of maximum change of density of a particular 

physicochemical variable—normally salinity or temperature—that segregates two 

distinct layers, which are of relatively homogeneous density. The presence of a 

pycnocline provides a barrier to vertical mixing between the upper and lower 

water columns, and this layer enhances the stability of the water column.

 Lower Water Column: The area below the pycnocline (or, if absent, below middepth in the water column), the lower portion of the water column is often dimly 

or negligibly illuminated (particularly in estuaries) and can be heterotrophic. 

These deeper waters have limited contact with the atmosphere, may be reduced in 

oxygen content, and can have a high degree of interaction with bottom sediments. 

This layer receives organic and mineral material from upper waters and is

frequently the site of anoxia. In estuaries, the salt wedge and counter current flow 

occur in this layer.

For shallow subsystems, the Water Column Layers are:

 Estuarine Coastal:

o Estuarine Coastal Surface Layer: Estuarine waters between the shore 

and the 4 meter depth contour at the surface of the water column to a 

depth of a few centimeters.

o Estuarine Coastal Upper Water Column: Estuarine waters above the 

pycnocline (or the mid-depth) between the shore and the 4 meter depth 

contour.

o Estuarine Coastal Pycnocline: Estuarine waters within the pycnocline,

between the shore and the 4 meter depth contour.

o Estuarine Coastal Lower Water Column: Estuarine waters below the 

pycnocline (or mid-depth) and between the shore and the 4 meter depth 

contour.

 Estuarine Open Water:

o Estuarine Open Water Surface Layer: Estuarine waters at the surface,

at or beyond the 4 meter depth contour.

o Estuarine Open Water Upper Water Column: Estuarine waters above 

the pycnocline (or mid-depth), at or beyond the 4 meter depth contour.

o Estuarine Open Water Pycnocline: Estuarine waters within the 

pycnocline, at or beyond the 4 meter depth contour.
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o Estuarine Open Water Lower Water Column: Estuarine waters below 

the pycnocline (or mid-depth), at or beyond the 4 meter depth contour.

 Estuarine Tidal Riverine Coastal:

o Estuarine Tidal Riverine Coastal Surface Layer: Tidal fresh waters at 

the surface, from the land-water interface up to the 4 meter depth contour.

o Estuarine Tidal Riverine Coastal Upper Water Column: Tidal fresh 

waters above the pycnocline (or mid-depth), from the land-water interface 

up to the 4 meter depth contour.

o Estuarine Tidal Riverine Coastal Pycnocline: Tidal fresh waters within 

the pycnocline, from the land-water interface up to the 4 meter depth 

contour.

o Estuarine Tidal Riverine Coastal Lower Water Column: Tidal fresh 

waters below the pycnocline (or mid-depth), from the land-water interface 

up to the 4 meter depth contour.

 Estuarine Tidal Riverine Open Water:

o Estuarine Tidal Riverine Open Water Surface Layer: Tidal fresh

waters at the surface, at or beyond the 4 meter depth contour.

o Estuarine Tidal Riverine Open Water Upper Water Column: Tidal 

fresh waters above the pycnocline (or mid-depth), at or beyond the 4 meter

depth contour.

o Estuarine Tidal Riverine Open Water Pycnocline: Tidal fresh waters 

within the pycnocline, at or beyond the 4 meter depth contour.

o Estuarine Tidal Riverine Open Water Lower Water Column: Tidal 

fresh waters below the pycnocline (or mid-depth), at or beyond the 4

meter depth contour.

 Marine Nearshore:

o Marine Nearshore Surface Layer: Marine waters at the surface, from 

the land-water interface up to the 30 meter depth contour.

o Marine Nearshore Upper Water Column: Marine waters above the 

pycnocline (or mid-depth), from the land-water interface up to the 30 

meter depth contour.

o Marine Nearshore Pycnocline: Marine waters within the pycnocline,

from the land-water interface up to the 30 meter depth contour.

o Marine Nearshore Lower Water Column: Marine waters below the 

pycnocline (or mid-depth), from the land-water interface up to the 30 

meter depth contour.
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 Marine Offshore:

o Marine Offshore Surface Layer: Marine waters at the surface, between 

the 30 meter depth contour and the shelf break.

o Marine Offshore Upper Water Column: Marine waters above the 

pycnocline (or mid-depth), between the 30 meter depth contour and the 

shelf break.

o Marine Offshore Pycnocline: Marine waters within the pycnocline, 

between the 30 meter depth contour and the shelf break.

o Marine Offshore Lower Water Column: Marine waters below the 

pycnocline (or mid-depth), between the 30 meter depth contour and the 

shelf break.

Figure 5.1. Marine Subsystems, Oceanic Water Column Layers, and Oceanic 

Benthic Depth Zones.

The Marine Oceanic Subsystem lies beyond the shelf break, extending to waters of great 

depth in the central ocean. The shelf break is defined as the point of maximum change in 

slope, a grade of up to 3 ̊ at the outer Continental Shelf, generally occurring between 100-

200 meters. The water column layers for this subsystem are scaled differently from those 
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of the other subsystems, because of the large spatial scale and the complexity and depth 

of the oceanic water column. Eight Marine Oceanic layers are defined using what are 

considered traditional oceanographic ecological and depth criteria and terminology:

 Marine Oceanic Surface Layer: The interface between the atmosphere and the 

water column, extending to a depth of several centimeters. Surface films, floating 

vegetation, and aggregations of materials or biota accumulate at the surface, 

which also represents the surface of maximum exchange of atmospheric gases, 

heat, and light.

 Marine Oceanic Epipelagic Upper Layer: The Epipelagic Layer is the upper 

200 meters of the oceanic water column. Within the Epipelagic, the Marine 

Oceanic Epipelagic Upper Layer is the region between the sea surface and the 

Epipelagic Pycnocline, if present, or mid-depth in the Epipelagic zone at 100 

meters. This layer is generally well-mixed, well-lighted, and highly oxygenated, 

and supports photosynthesis largely throughout, although weakly in the lower 

depths. It has no contact with, and very minimal influence from land, and is very 

clear compared to coastal water masses. It is the zone of maximal productivity in 

the Oceanic Subsystem.

 Marine Oceanic Epipelagic Pycnocline: Within the Epipelagic Layer, the 

Marine Oceanic Epipelagic Pycnocline is the zone of maximum vertical change in 

density of the water normally due to a salinity or temperature gradient, which 

segregates the water column into two distinct layers that are of relatively 

homogeneous density. The presence of a pycnocline provides a barrier to mixing 

between the upper and lower water columns, and this layer enhances the stability 

of the water column preventing mixing to the bottom.

 Marine Oceanic Epipelagic Lower Layer: Within the Epipelagic Layer, the 

region below the Epipelagic pycnocline if present (or below mid-depth [100 

meters]). Photosynthesis can generally occur through this layer although 

diminishing with depth to the critical depth for phytoplankton, which represents 

the point where production and respiration are in balance and no net productivity 

occurs. The lower bound of the Epipelagic Lower Layer is the bottom of the 

Epipelagic Layer at 200 meters.

 Marine Oceanic Mesopelagic Layer: The region where light is vertically 

attenuated to below the level required for photosynthesis, generally between 200 

meters and 1,000 meters in depth. Oxygen declines rapidly to a minimum, 

corresponding with the lower limit of the Mesopelagic Zone—due to high 

bacterial respiration from settling organic material.

 Marine Oceanic Bathypelagic Layer: The region where light does not penetrate, 

rendering the water column totally dark except for bioluminescence, generally 

from 1,000 meters to 4,000 meters depth. Organisms at these depths are subjected 

to immense pressure; food webs depend on organic detritus rather than active 
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photosynthetic production. Waters in this layer generally are composed of cold,

bottom currents (from sinking water masses descending from polar latitudes).

 Marine Oceanic Abyssopelagic Layer: The region of the water column that is 

generally in contact with the abyssal seafloor, except in deep basins and trenches 

and represents the bottom layer of the ocean, generally from 4,000 meters to 

6,000 meters depth. This layer is aphotic; it receives biogenic, detrital and mineral 

material descending from above and this layer acts as an accumulation zone. 

Oozes from tests of planktonic organisms form on the seafloor and fans of 

sedimentary material accumulate here. There are diverse and specialized faunal 

communities at these depths. Trophic webs are based on chemoautotrophic 

processes, hydrothermal vents, decomposition of organic matter and bacterial 

production.

 Marine Oceanic Hadalpelagic Layer: The deepest waters of the globe occur in 

trenches and deep basins generally at depths greater than 6,000 meters. There is a 

high degree of tectonic and thermal activity in these areas. Waters in this layer

have unique characteristics of immense pressure, strong currents, accumulation of 

sediments and organic material; macrofauna that occur at these extreme depths 

have special feeding strategies and adaptations to intense pressure and total 

darkness.

5.2 Salinity Subcomponent

Salinity in seawater results from a concentration of salts including bromine, iodine, and 

(principally) sodium chloride. Salinity is measured as a dimensionless conductivity ratio 

on the practical salinity scale (PSS), which was established by the IAPSO (International 

Association for the Physical Sciences of the Oceans) in 1978 (UNESCO 1981). Most 

marine waters have salinities between 34 and 35, while in estuaries and coastal waters 

salinity can vary considerably from zero to hyperhaline (≥ 40). In estuaries, the salinity 

distribution is a function of direct precipitation, the influx of freshwater supplied by 

rivers, groundwater sources and runoff from the land and marine water supplied by 

exchange with the ocean as a function of tidal regime. Salinity is an indicator of the 

dynamic or conservative nature of mixing within the water body, and is one of the 

defining features of the structure of coastal waters. Most aquatic organisms function 

optimally within a narrow range of salinities, which has impact on the ecological balance 

and trophic structure of communities. Salinity categories and ranges for CMECS are 

provided in Table 5.2.
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Table 5.2. Categories and Ranges for the Salinity Subcomponent.

Salinity Regime Salinity (Practical Salinity Scale)

Oligohaline Water < 5

Mesohaline Water 5 to < 18

Lower Polyhaline Water 18 to < 25

Upper Polyhaline Water 25 to < 30

Euhaline Water 30 to < 40

Hyperhaline Water ≥ 40

5.3 Temperature Subcomponent

Temperature is a measure of kinetic energy, and in most cases decreases with depth in the 

water column. The mean temperature of oceanic seawater, which by volume is 

principally at depth, is generally low, 0 – 5

oC, but higher in the water column 

temperatures tend to converge toward air temperature at the surface. Marine waters are 

structured vertically with a mixed surface layer having little gradient in temperature, a 

thermocline with a highly variable gradient, and underlying waters with little 

stratification. A thermocline is established between an upper layer of one temperature and 

a lower layer of another and can be seasonal or permanent depending on the circulation 

and weather patterns. Pronounced thermoclines occur in the tropics, and essentially none 

occur in Polar Regions. In estuaries, temperatures are more variable because waters are 

shallower and under more influence of the temperature of inflowing freshwaters or of 

tidal marine waters. Temperature has a considerable impact on ecosystem functioning, 

affecting photosynthesis, growth, metabolism, and mobility of organisms. Rates of 

microbial processes of decomposition, nitrogen fixation and denitrification generally 

double with each increase of 10oC. Organisms tolerate a particular temperature range, 

and the temperature optimum range may span only a few degrees. The solubility of gases 

and pH are dependent on temperature, and temperature influences the ability of water to 

hold oxygen or oxic status. 

Temperature categories are established in intervals of sufficient range and resolution to 

provide meaningful ecological differences yet yield a parsimonious number of categories.

Temperature categories are based on the British Columbia Marine Ecological 

Classification for Canada (Howes, Harper, and Owens 1994, Zacharias et al. 1998, 

Resource Information Standards Committee 2002), modified to add the higher 

temperature ranges typical of the subtropics and tropics. Categories for water mass 

temperature are established in Table 5.3.
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Table 5.3. Categories for Water Temperature.

Temperature Category Degrees (°C)

Frozen/Superchilled Water 0 and below

Very Cold Water 0 to < 5 (liquid)

Cold Water 5 to < 10

Cool Water 10 to < 15

Moderate Water 15 to < 20

Warm Water 20 to < 25

Very Warm Water 25 to < 30

Hot Water 30 to < 35

Very Hot Water ≥ 35

5.4 Application of Water Column Layer (L), Salinity (S) and 

Temperature (T) Subcomponent Units

Many applications of classification may be satisfied by characterizing the water column 

using any of the subcomponents singly. However, more powerful information can be 

developed by combining subcomponents. Salinity (S) and/or Temperature (T) can be 

combined with Layer (L) to produce unique S-L, T-L or T-S-L combinations as needed. 

It is highly recommended that the Layer information always be applied to the other 

subcomponents when data are available. All possible combinations of units are too 

numerous to practically display; however, below are examples of how the Water Column 

Layers can be combined to create combinations pertinent to several subsystems. The 

order of subcomponents is: Temperature, Salinity, and Layer.

Layer: Estuarine Coastal Surface Layer

Example SL: Upper Polyhaline Estuarine Tidal Riverine Coastal Surface 

Layer

Example TL: Warm Estuarine Tidal Riverine Coastal Surface Layer

Example TSL: Warm Upper Polyhaline Estuarine Tidal Riverine Coastal 

Surface Layer

Layer: Estuarine Coastal Upper Water Column

Example SL: Mesohaline Estuarine Coastal Upper Water Column

Example TL: Cool Estuarine Coastal Upper Water Column

Example TSL: Cool Mesohaline Estuarine Coastal Upper Water Column
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Layer: Estuarine Coastal Pycnocline

Example SL: Euhaline Estuarine Coastal Pycnocline

Example TL: Cold Estuarine Coastal Pycnocline

Example TSL: Cold Euhaline Estuarine Coastal Pycnocline

Layer: Marine Nearshore Lower Water Column

Example SL: Upper Polyhaline Marine Nearshore Lower Water Column

Example TL: Moderately Warm Marine Nearshore Lower Water Column

Example TSL: Moderately Warm Upper Polyhaline Marine Nearshore 

Lower Water Column

Layer: Marine Offshore Upper Water Column

Example SL: Euhaline Marine Offshore Upper Water Column

Example TL: Warm Marine Offshore Upper Water Column

Example TSL: Warm Euhaline Marine Offshore Upper Water Column

Layer: Marine Oceanic Mesopelagic Layer

Example SL: Euhaline Marine Oceanic Mesopelagic Layer

Example TL: Cool Marine Oceanic Mesopelagic Layer

Example TSL: Cool Euhaline Marine Oceanic Mesopelagic Layer

5.5 Hydroform Subcomponent Hierarchical Structure

Hydroforms are physical entities that have a coherent, definable structure with 

identifiable boundaries and characteristic physical properties. The Hydroform 

Subcomponent is a hierarchy of three levels consisting of Hydroform Classes, 

Hydroforms and Hydroform Types. Hydroforms are ecologically important because they 

shape their environment by creating gradients, surfaces, barriers, compartments and 

energy vectors. They strongly influence the distribution and condition of biota and often 

act as habitat by creating a complex environmental structure, by facilitating and 

enhancing transport of materials and energy, cycling nutrients, providing refugia, 

aggregating food resources, and providing migration paths. They influence the transfer of 

heat, salts, oxygen, carbon dioxide, trace elements, momentum, predicted trajectory, 

temporal persistence and associated fauna. Hydroforms vary extensively in size, volume, 

areal extent, persistence, and ecological significance.

In this standard hydroforms are represented conceptually as the average expression of 

their defining characteristics. The boundaries of the hydroforms are to be determined by 

methodology, technology limits, user objectives and application and lie along a 

continuum. Implementation guidance will be developed to assist in determining 

quantitative cutoffs that define their boundaries.
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5.5.1 Hydroform Classes 

Hydroform Classes are major groups of oceanic and coastal water column forms: 

Currents, Water Masses, Fronts, and Waves. Currents represent the advective movement 

of a mass of water, important in transport and circulation. Water masses are large, 

coherent parcels of water that reflect homogeneous properties and are distinct from 

surrounding waters. They may be moving or stationary. Fronts form at the interface 

between waters of two different masses or types with distinctly different characteristics. 

The frontal boundary represents the intense gradient between them. Waves are the 

propagation of energy through the water column and impact water column mixing, 

movement of biota, shoreline impact, and oxygenation and represent an input

disturbance. These basic units are found throughout the world’s estuaries and oceans 

across multiple temporal and spatial scales and each major Hydroform Class can be 

broken into many more specific forms as described below.

5.5.2 Hydroforms and Hydroform Types

Hydroforms are nested within Hydroform Classes and are distinguished by scale, system, 

location or other attributes of the Hydroform Class. Examples include Langmuir 

circulation (Current), Mesoscale Lens (Water Mass), Tidal Front (Front), and Internal 

Wave (Wave). Hydroforms can be broken down further into Types based on 

distinguishing characteristics such as temperature, energy level, circulation patterns, and 

geography.

5.6 Hydroform Subcomponent Units

Hydroform Class: Current

Water that is undergoing coherent mass movement, either as laminar or turbulent flow, 

relative to surrounding waters and fixed structural, landform or geologic features. A 

directional, coherently flowing water mass. Currents operate on a wide range of temporal 

and spatial scales from huge ocean gyres and major surface and deepwater currents of the 

ocean operating on annual timescales to tidal currents that operate on sub daily

timescales. However, all currents have features in common: the advective movement and 

transport of water, constituents (such as particulates and dissolved compounds), qualities 

(such as temperature and salinity) and biota (such as plankton, nekton, and megafauna). 

Currents are driven by gravity flow, geostrophic flow, density differences, hydraulic 

differential or energy input. They may be isolated from land and freely flowing in the 

water column as is the Gulf Stream, or they may be in channelized flow or long-shore 

flow. Currents that impact land also shape the littoral zone or sea bottom by winnowing 

sediments, physically mixing or shearing substrates and biota and creating geoforms such 

as sand ripples and bars. 
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 Hydroform: Boundary Current – The portion of an ocean gyre that 

moves along the continental boundary.

o Hydroform Type: Eastern Boundary Current (EBC) – The 

eastern portion of the great ocean gyres circulating in the ocean 

basins against west continental coasts. They may be broad or 

narrow and meandering; they transport colder water into the 

tropics. EBCs are typically shallow and slow-flowing compared 

to the Western boundary currents. EBCs may be associated with 

upwellings and nutrient rich seas that can support very productive 

fisheries, such as in the Peruvian Upwelling. 

o Hydroform Type: Western Boundary Current (WBC) – The 

western portion of the great ocean gyre circulation, which moves 

along the eastern coasts of the continents. These currents are 

deeper (up to 1,000 meters) and faster moving than eastern 

counterparts. The western intensification, due to Coriolis forces 

being stronger in the latitudes of the Westerlies that steer Western 

boundary currents, is responsible for the great speed and intensity 

of these currents. WBCs transport warmer tropical waters into the 

cold higher latitudes and have a great effect on both oceanic and 

terrestrial climate, water temperatures and distribution of biota.

 Hydroform: Buoyancy Flow – Current flow created by discontinuity in 

buoyancy of two juxtaposed water masses of different density, causing 

one to flow relative to the other toward buoyancy equilibrium.

o Hydroform Type: Downwelling – Downwardly-directed current 

caused by convergence of water masses.

o Hydroform Type: Upwelling – Upwardly-directed current caused

by divergence of water masses

 Hydroform: Current Meander – A current that deviates from a straight 

line flow, which is often the result of incursion by lateral currents or the 

presence of a physical or density barrier. Meanders can pinch off from the 

main current flow and form rings.

 Hydroform: Deep Boundary Current – A current that connects highlatitude ocean waters (where deep water is formed) with upwelling 

regions. The core depths of these currents are between 1,500 meters and 

4,000 meters. Western-located Deep Boundary Currents lie adjacent to 

continental slopes in all ocean basins.
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 Hydroform: Deep Circulation – The mass circulation of the oceans that 

carries cold polar surface water to depth, sinking due to higher density 

and wind forcing. The mass transport also carries salt, oxygen, and other 

properties. Deep circulation is wind driven, with a tidal mixing

component. It cools the surface and evaporates water, which determines 

where deep convection occurs. Wind-driven turbulence in the deep ocean 

mixes cold water upward at lower latitudes. Deep circulation has relative 

slow current movements but transport of water is comparable to surface 

transport and is responsible for closing the Earth’s heat budget and 

determining climate.

o Hydroform Type: Abyssal Deep Circulation – Deep, slow 

circulation in the abyssal zone driven by horizontal differences in 

density of water masses. The vast majority of ocean circulation is 

of this type, initiating by the sinking of cold water in the high 

latitudes to the ocean bottom, and spreading throughout the abyssal 

plains of the ocean basins.

o Hydroform Type: Bathyl Deep Circulation – Deep, slow 

circulation in the bathyl zone driven by horizontal differences in 

density of water masses. Water sinks down the continental slope 

and through the bathyl zone as part of thermohaline ocean 

circulation.

 Hydroform: Deep Convection – Large mass flows of water in the deep 

ocean that form critical parts (and return paths) of the great ocean 

circulation.

 Hydroform: Density Flow – Flow caused by differential density between 

two convergent water masses—or by a parcel of denser water flowing 

along a sloping bottom under a column of less-dense water. 

 Hydroform: Ekman Flow – The flow of water at 90 ̊ to the direction of 

the wind, at steady state, due to Earth’s rotational effect.

o Hydroform Type: Ekman Upwelling – Upwardly-directed 

current resulting from either the divergence of water masses or 

from movement of surface water away from the coast. At the 

divergence of two water masses (or the wind-driven movement of 

water away from a coastline), continuity of mass flow will move 

water from depth to the surface as replacement. In the nearshore, 

the circulation will bring the water from the shallow bottom. In 

deeper waters, the upwelling will carry water from a variety of 

depths—from near the surface to depths to as great as 500 meters

(below the pycnocline). Because the upwelled water is working 

against gravity, its maximum influence is not as great as 
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downwelled water (which is aided by gravity); however, the 

upwelling can reach into the mesopelagic zone.

o Hydroform Type: Ekman Downwelling – Downwardly-directed 

current, resulting from either the convergence of water masses or 

from the convergence of a water mass with a coastline. At this 

convergence, gravity will force water into a downwelling, which 

will carry surface water to greater depths. In the nearshore, the 

circulation will take the water to the shallow bottom and then 

move seaward. In deeper waters, the downwelling will carry water 

to a depth determined by energy dissipation and relative density 

considerations; the maximum downwelling depth can be into the 

abyssalpelagic zone. 

 Hydroform: Inertial Current – Currents that continue motion through 

inertia. Due to the rotation of the Earth, inertial currents tend to form 

circular gyres.

 Hydroform: Langmuir Circulation – Rotational oscillatory motion of 

surface waters induced by wind and Coriolis deflection. This circulation is 

caused by the transport of a parcel of water obliquely to the direction of 

wind transport due to the apparent Coriolis force imparted by the rotation 

of the Earth. In the Northern Hemisphere this vector is to the right of the 

wind direction, in the Southern Hemisphere, it is to the left. This causes a 

piling of water in cells lateral to the direction of travel. The piled water 

sinks to balance forces, and it also circulates to create elongated tubular 

circulations of water at the surface. Langmuir cells are important to 

productivity by circulating water through the water column, and form 

fronts at the junction of two Langmuir cells that are important points of 

aggregation and feeding of plankton and higher trophic levels (Wetzel 

2001).

 Hydroform: Mean Surface Current – The time-averaged steady state 

ocean surface current pattern responsible for mean oceanic water motions.

o Hydroform Type: North Equatorial Surface Current – The 

southern portion of the northern ocean gyres. This current flows 

westward, is maintained by the trade winds, and entrains some 

water from southern oceans into the northern oceans. It is 

accompanied by a weaker easterly-flowing counter current.

o Hydroform Type: South Equatorial Surface Current – The 

counterpart to the North Equatorial current, also flows east to west, 

forming the northern limb of the southern ocean gyres.
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 Hydroform: Mesoscale Eddy – A rotational feature that (a) breaks off of 

an ocean gyre or large current (such as the Gulf Stream) and (b) persist 

autonomously for some period (from days to months) at sizes of 20 

kilometers to 500 kilometers. These eddies play an important role in ocean 

mixing—and in sheltering and acting as nursery waters for biota. The most 

energetic eddies are at the smaller end of the spatial scale. The larger 

eddies (called mesoscale eddies) are slower moving, but they persist for 

many months and are ubiquitous in the global oceans. Mesoscale Eddies

are most prevalent in the North Atlantic and North Pacific, but they can 

occur in all oceans.

o Hydroform Type: Cold Core Ring – An eddy that forms when a 

boundary current meander pinches off and closes, trapping a parcel 

of colder water in a surrounding ring of warmer water. The ring 

measures up to 300 kilometers and extends to 4,000 meters depth 

or the ocean bottom. The colder water in the core tends to be 

higher in nutrients and more productive than that in the 

surrounding ring, so they become islands of biological activity as 

they move through the ocean. Rings form in all oceans and can 

persist for months to years. 

o Hydroform Type: Warm Core Ring – An eddy that forms when 

a boundary current pinches off a parcel of warmer water. The ring 

measures 100-200 kilometers and extends to 1,500 meters depth.

The warm water in the core tends to be less productive than the 

colder, nutrient rich waters in the ring.

 Hydroform: Residual Current – Current movement resulting from 

asymmetry in tidal flow—notably within a partially enclosed estuary or 

embayment—that results in characteristic estuarine circulation patterns.

o Hydroform Type: Fjord Circulation – Circulation in estuaries 

that possess a sill at the seaward end, inhibiting inflow of seawater 

into the bottom waters. Seawater flows over the sill mixing into 

the intermediate water of the estuary, and sinking to the bottom. 

The estuary receives freshwater input in excess of evaporation and 

the resulting brackish mixture is exported across the sill into the 

ocean end-member. The limited exchange of bottom waters can 

promote hypoxic conditions in some fjord estuaries.

o Hydroform Type: Partially Mixed Domain – An estuarine 

circulation with an intermediate level of advective and tidal energy

that can disrupt the density barrier between the fresher upper and 

salty lower water column of an estuary, entraining water in both 

directions. This results in a gradient of increasing salinity from top 

to bottom, with no barrier to mixing.
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o Hydroform Type: Reverse Estuarine Flow – An estuarine 

circulation where evaporation greatly exceeds freshwater input, as 

in hot dry climes, salinity is concentrated within the estuarine 

basin. This results in a salinity maximum in the estuary that can far 

exceed seawater salinity.

o Hydroform Type: Salt Wedge Domain – Portions of estuaries 

that have an unimpeded connection of bottom waters to the sea 

develop a wedge-shaped formation of high-salinity water in the 

bottom, with lower salinity water from upstream freshwater 

loading in the upper water column. The wedge form is developed 

as hydrostatic pressure of river water pushes against the incoming 

seawater and, being less dense, rides over it. The difference in 

salinity and density is important in estuarine chemistry and biology 

as the density barrier between upper and lower water columns 

restrains mixing and transport across the transitional gradient, 

called the pycnocline. This leads to an upper, autotrophic and 

lower, generally heterotrophic portion of the water column.

o Hydroform Type: Well-mixed Domain – Reaches of estuaries 

where the tidal flux and/or the river discharge is sufficient to 

overcome the salt-wedge structure, the water column becomes 

well-mixed and vertical homogeneous.

 Hydroform: Sub-mesoscale Eddy – A reverse current with rotational 

movement created when fluid flows past an obstacle. Sub-mesoscale 

eddies are of size scale smaller than 20 kilometers.

 Hydroform: Thermohaline Eddy – Eddy formation due to the 

interaction of temperature and salinity differences between two water 

masses initiating convective flow.

 Hydroform: Tidal Flow – Advective flow resulting from of tidal 

movement, often amplified in velocity when moving through an inlet, pass 

or channel. Tides are important in mixing the water column and 

transporting water, salt, nutrients and biota, particularly weak-swimming 

larval or non-motile planktonic forms. The life cycles of many organisms 

depend on tidal transport for survival.

o Hydroform Type: Diurnal Tidal Flow – Tidal ocean waters 

where, due to the geometry of the ocean basin and obstructions 

presented by land, a second daily tide is suppressed, resulting in a 

single or diurnal tide regime with one high and one low tide per 

day, as in the Gulf of Mexico.
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o Hydroform Type: Mixed Semi-diurnal Tidal Flow – Tidal 

ocean waters where the amplitudes of two semi-diurnal tides are 

unequal, resulting in a stronger and a weaker high and low tide 

each day.

o Hydroform Type: Semi-diurnal Tidal Flow – Tidal ocean waters 

where the gravitational action of the sun and moon on Earth’s 

oceans create two high and two low tides per day of relatively 

equal amplitude.

 Hydroform: Turbidity Flow – A flow of water down slope carrying a 

dense suspension of fluid mud or unconsolidated material.

 Hydroform: Wave-driven Current – Residual current caused by 

asymmetrical force created by wave motion.

o Hydroform Type: Longshore Current – A current that moves 

parallel to or at an oblique angle to the shoreline, carrying water

and often transporting soft sediments downstream. Prevailing wind 

and wave directions can persist in a longshore direction for long 

periods, and are commonly responsible for the formation of spits, 

bars and many barrier islands. 

o Hydroform Type: Rip Current – A formation of water flow in a 

seaward direction generated by wave action and local topography 

nearshore. Shallow depressions in the sea floor or breaks in a bar 

will channel receding water at high velocity away from shore and 

through the surf zone after onshore wave action. 

o Hydroform Type: Undertow – Seaward-directed current 

generated by water that is receding from the shoreline after wave 

run up.

 Hydroform: Wind-driven Current – Current caused by wind shear as 

distinguished by those caused by density differences, which result in 

thermohaline circulation. Though only a portion of the oceans are exposed 

to wind energy, winds are responsible for the great ocean gyres, dominant 

features of ocean circulation.

Hydroform Class: Front

Front Hydroforms are linear features formed at the conjunction of two or more water 

masses with different properties. Fronts are formed in many different ways when two 

water masses juxtapose. The front itself becomes a third water feature, and it has several 

distinctive properties of its own, including current speed and direction, physicochemical 

properties derived from the two merging water masses, sharp gradients in properties
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(such as salinity, temperature, nutrients and water clarity) and an accumulation of matter 

and biota. In estuaries, fronts can occur at the boundaries of horizontal layers between 

fresher upper layers and saltier bottom waters; in the ocean, fronts can occur between the 

upper mixed layer and lower layers.

 Hydroform: Coastal Upwelling Front – A frontal interface where a 

nearshore upwelling occurs due to local turbulent mixing. The upwelling 

front develops between the upwelling water and the coastal water mass.

 Hydroform: Shelf-break Front – Frontal formations where cross-shelf 

waters encounter slope waters from the deeper oceans, often associated 

with upwelling. The seasonally transitional features are sites of high 

temperature, salinity and density gradients and often of high productivity 

where deep upwelled water contributes high nutrients.

 Hydroform: Tidal Front – A front created by the linear convergence of 

two water masses brought into juxtaposition by tidal action. Generally the 

two masses will have differential characteristics such as temperature, 

density, and often of color and productivity. Fronts can be maintained as 

distinct due to these differences, which inhibit mixing across a density 

barrier. There is often strong vertical mixing on either side of the front, 

producing upwelling and aggregations of biota feeding on the material 

grown in situ or accumulated at the front.

Hydroform Class: Water Mass 

The Water Mass Hydroform Class refers to a parcel of water with homogeneous 

properties (e.g., chemical, physical). If no other hydroform applies (or sufficient 

information is not available to classify the hydroform), the default would be a water mass

that describes the general properties of the parcel. Any physicochemical property (or 

properties) can define a water mass. Common water mass types are those of 

homogeneous salinity, temperature or density—or a combination of those properties. The 

properties of a water mass generally change relatively slowly, because the factors that 

created and constrain the homogeneity tend to be buffered by the inertial properties of 

water itself. Thermal mass of water, for example, means that the water temperature will 

change much more slowly than air temperature. Non-conservative properties (such as 

nutrient concentration or pH) can change much more quickly, because biological 

processes can alter them.

 Hydroform: Background Mesoscale Field – A water mass characterized 

by organized ocean-surface currents formed by coupled eddies (at the 

mesoscale length scale); responsible for much of water movement on the 

ocean surface.
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 Hydroform: Fumerole Plume – A plume of hot gases venting from the 

sea bottom associated with volcanic or tectonic activity from cracks in the 

Earth’s crust; often a site of significant chemoautotrophic activity.

 Hydroform: Hydrothermal Plume – A discharge of hot fluids from seabottom vents associated with volcanic or tectonic activity. The fluids are 

often laden with high concentrations of minerals, which impart either a 

dark—even black—color or a white color. These minerals precipitate 

readily out of supersaturation.

o Hydroform Type: Detached Hydrothermal Plume – A parcel of 

hot, mineral rich water that has become detached from its source 

and forms a persistent lens within the water column.

 Hydroform: Ice – Frozen form of water, which is less dense than liquid 

water; ice floats on the surface of liquid water, sometimes extending into 

deep water zones. This property drives a number of important biological 

and physical processes in the ocean, including preventing freezing of the 

ocean to the bottom. Ice either floats on—or forms a solid cover on—the 

underlying water, which isolates atmospheric input for the duration of 

cover. Nonetheless, strong circulation and water motion occurs in the 

aquatic system under the ice (driven by advection of adjacent water 

masses or thermal convection). Because freshwater freezes at a higher 

temperature than salt water, surface freezing of the ocean concentrates salt 

brine in the liquid water below the ice. Ice formation and ice cover 

maintenance is relatively stable in both spatial and temporal terms, 

determined by relative air and water temperatures, velocity of water 

movements, and geomorphology of the setting.

o Hydroform Type: Drift Ice – Ice that floats freely on the sea 

surface.

o Hydroform Type: Fast Ice – Ice that is attached to a land mass 

such as the coast or, in shallow water, the sea floor.

o Hydroform Type: Frazil or Grease Ice – Ice formation that 

develops when super-cooled water is turbulently mixed, permitting 

development of small ice crystals which continually fragment and

break up without forming ice cover. Over time a slushy suspension 

of increasing density forms on the surface of the water. In quiet 

conditions frazil crystals can freeze together to form a continuous 

thin sheet of young ice.

o Hydroform Type: Ice Field – Expanse of ice greater in size than 

an ice floe (≥10 kilometers in any dimension).
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o Hydroform Type: Ice Floe – Large floating ice chunk less than 

10 kilometers on its longest axis.

o Hydroform Type: Pack Ice – Accumulation of drift ice into a 

large floating mass, often against a continental shoreline.

o Hydroform Type: Pancake Ice – Thin plaques of compressed ice 

particles formed by wave action into plates several meters in 

diameter that float on the sea surface.

o Hydroform Type: Polnya – An area of open, liquid seawater 

surrounded by ice.

 Hydroform: Mesoscale Lens – A trapped, homogeneous parcel of water 

lying within (or atop) larger ocean fields due to density differences. These 

hydroforms are 30 - 300 kilometers in size.

o Hydroform Type: River/Estuary Plume – Formation of water

resulting from the discharge of low-salinity water into marine 

waters of the ocean, forming a distinct layer of water on top of the 

seawater due to its lower density. The plume can extend for many 

kilometers and persist for months after the freshwater flow has 

stopped before being entrained into the seawater. These plumes are 

typically higher in nutrients, turbidity and productivity than the 

surrounding seawater and can gradually deliver those water quality 

characteristics to the adjacent ocean water.

o Hydroform Type: Meddy – A lens of water that enters the eastern 

Atlantic from the Mediterranean Sea, flows down the Continental 

slope and pinches off at the depth of neutral buoyancy, about 1,000

meters. The salty warm water rotates clockwise and travels slowly 

westward in the Atlantic, persisting for many months. 

 Hydroform: Microscale Lens – A homogeneous parcel of water on the 

order of meters to a few kilometers positioned within (or atop) a larger 

ocean fields of different density.

o Hydroform Type: Small Freshwater Plume – Similar to a river 

plume but on smaller scale and can be initiated from variety of 

sources such as a groundwater seep, a non-point source or a 

transient discharge.

 Hydroform: Winter Water Mass – The mass of water produced—and 

introduced to oceans—as a result of melting winter ice formations. These 

water masses tend to be fresher than surrounding waters, and they often 

flow over the denser salt water.
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Hydroform Class: Wave

The Wave Hydroform Class is a propagation of energy that moves through the water,

causing a vertical, oscillatory motion with characteristic wavelength, amplitude, and 

celerity. Waves are of several types: internal, standing, and surface. Each type of wave 

propagates energy and impacts the waters, substrate, and biota that it contacts. Waves are 

initiated by an energy source (such as wind, landslides, Earthquakes, or volcanic 

eruptions), and they can occur at any depth in the water column. Wave energy varies 

depending on type and intensity of energy input; the wave regime can change on hourly 

timescales. 

 Hydroform: Anthropogenic Wave – Boat wake or other wave caused by 

energy resulting from human activity.

 Hydroform: Coastally Trapped Wave – A wave that moves along the 

coastal margin, which forms a trapping barrier.

o Hydroform Type: Internal Kelvin Wave – Subsurface gravity 

wave with a rotational component propagated along a density 

interface against a vertical barrier such as a coast or the wall of a 

basin.

o Hydroform Type: External Kelvin Wave – Surface gravity wave 

with a rotational component propagated along the sea surface 

against a vertical barrier such as a coast or the wall of a basin. 

Such Kelvin waves are important at the Equator in determining the 

presence and strength of El Niño/ENSO events.

o Hydroform Type: Shelf Wave – A wind-induced wave guided by 

continental shelf topography.

o Hydroform Type: Topographic Wave – A sub-basin scale wave 

that is driven by wind-stress from the passage of cyclones across or 

along the shelf, with long period (~ 5 days) and to which a 

vorticity is imparted by the apparent Coriolis Effect.

 Hydroform: Edge Wave – A wave that moves along a trapping barrier, 

such as the continental shelf, the continental margin or an inertial water 

mass.

 Hydroform: Equatorial Wave – A wave that is trapped by and moves 

along the Equatorial water mass, which forms a density barrier.
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 Hydroform: Non-Equatorial Wave – A wave that is propagated along an 

edge or barrier, such as a continental margin, and that is not associated 

with an equatorial water mass.

 Hydroform: Internal Wave – A wave that propagates along a density 

surface within the water column, below the water’s surface.

 Hydroform: Seiche – A long-period, standing wave that creates an 

oscillatory sloshing of water within an enclosed water body. This is due to 

wind or pressure effects that cause water motions that resonate with the 

length scale of the water body.

 Hydroform: Storm Surge – A propagation of water associated with 

intense meteorological and wind activity such as a tropical storm. The 

surge of water from deep into shallow waters and onto land is caused by 

wind forcing in the forward, shoreward direction and by pressure 

differential within a cyclonic storm that positions extreme low pressure 

over a section of ocean, permitting tides to rise above normal range.

 Hydroform: Surf Zone – Zone with incipient wave breaks, which are the

result of an increase in the steepness of the wave as the water depth 

decreases. The surf zone is the region extending from the seaward 

boundary of wave breaking to the limit of wave uprush. The surf zone is 

the specific subset of the wave hydroform where waves are breaking 

against a shoreline. This relatively narrow area occurs when waves 

encounter bottom friction and break, forming a region of high turbulence, 

mixing, and intense energy. This occurrence affects biota in the water 

column, as well as bottom and shore substrates and biota. The surf zone is 

highly variable temporally and spatially in extent, energy characteristics, 

and physicochemical properties; this variability is due to the tight coupling 

between the water column and the substrate it impacts. In areas of soft 

sediments, high turbidity can result. Benthic biota (such as diatom mats)

can be mixed into the water column, imparting its photosynthetic 

parameters to the water column and elevating water-column productivity. 

Nutrients can also be mixed from disturbed sediments into the water 

column, elevating concentrations there.

 Hydroform: Surface Wave – A wave generated by energy input from 

sources such as wind, landslides, tidal action, or current action, and that 

moves along the surface of the ocean.

 Hydroform: Surface Wind Wave – A surface wave generated by direct 

wind action on the water’s surface producing shear, piling up water in the 

direction of the wind and generating a wave.
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 Hydroform: Surface Swell – A surface gravity wave propagating into an 

area from a distant source of energy/disturbance and that is not caused by 

direct local action of the wind.

 Hydroform: Tsunami – A large long-wavelength (tens or hundreds of 

kilometers) ocean wave that is generated by a powerful undersea 

disturbance such as a landslide, Earthquake, or volcano. The wave is 

nearly imperceptible in the open ocean but as it approaches land, it can 

reach heights of many tens of meters. They can have enormous destructive 

impact on the coast (and inland), as well as the biology of the nearshore 

zone.

5.7 Biogeochemical Feature Subcomponent

The Biogeochemical Feature more specifically defines the water column by identifying 

factors including constituent composition (e.g., chlorophyll maximum, turbidity

maximum), physical energy (e.g., light, surface mixed layer,), and gradients (halocline, 

thermocline). The Biogeochemical Feature subcomponent provides information that 

conveys the structure and the processes that form and sustain the feature—as well as its 

potential relationship with the biota. The feature integrates specific information, which

may include ecoregion, climate zone, position in the water column, position relative to 

land and spatial scale that is ecologically relevant. The Biogeochemical Feature also 

conveys information about properties of the other water column subcomponents. 

5.7.1 Biogeochemical Feature Subcomponent Units 

 Benthic Boundary Layer – The layer formed at the interface between the lower 

water column and the benthic substrate.

 Boundary Layer – Layer formed at the interface between water and another 

water mass (or solid interface) where frictional shear forces on water motion 

cause exponential damping of movement with proximity to the interface.

 Chlorophyll Maximum – A feature in deeper water columns (often in the ocean), 

where phytoplankton production is locally high at depths along a surface of 

nutrient (nitrate) entrainment from lower-water layers.

 Chlorophyll Minimum – A layer of low chlorophyll—and hence 

phytoplankton—concentration (relative to adjacent waters) due to highly 

concentrated grazing activity.

 Drifting Fine Woody Debris – Aggregations of floating or suspended fine 

woody material such as small tree branches, husks or fibrous seeds, with a median 

particle size < 64 millimeters.
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 Drifting Herbaceous Debris – Floating or suspended detached, decaying 

herbaceous plant matter such as leaves, forbs or grasses, including deciduous 

leaves or needles, palm leaves, seagrass debris, Spartina debris.

 Drifting Trees – Floating or suspended large dead trees or very large branches, 

with a median particle size of greater than 4,096 millimeters.

 Drifting Woody Debris – Floating or suspended detached large branches with a 

median particle size of 64 millimeters to < 256 millimeters such as Mangrove

branches, coconut rafts.

 Euphotic Zone – The zone of the water column that is sufficiently illuminated for 

photosynthesis to occur.

 Halocline – The zone of rapid salinity change with depth in the water column, 

often separating two layers of different, homogeneous salinity. As the density of 

water changes with salinity, the halocline presents a barrier to vertical circulation

and enhances water column stability

 Lens – A homogeneous parcel of water that—by composition—maintains 

coherence within water of different properties. Often a freshwater lens will sit 

perched atop saline ocean waters for long periods.

 Lysocline – The depth in the ocean at which calcium dissolution increases due to 

increased pressure. This depth is around 4,000 meters in the Pacific Ocean and 

5,000 meters in the Atlantic Ocean, owing to differences in temperature and 

chemistry. Below this depth, the precipitation of calcium carbonate decreases 

rapidly to the point where no calcite is deposited.

 Marine Snow Aggregation – A concentration of organic material in the ocean 

water column. Composed of a mix of mineral, dead organic materials, and—

sometimes—a rich microbial community. In this feature small particles aggregate 

through attractive ionic forces and then begin to fall through the water column.

 Microlayer – Any extremely thin layer of material, nutrients, organisms or 

specific properties that exists on or in the water column. The microlayer can be a 

surface film or at depth and often refers to a microbial film.

 Nepheloid Layer – Layer of water that contains a high concentration of silt and 

sediment—usually at the benthic-water column interface. This layer can be nearly 

a fluid mud. In the deep oceans, the layer can be hundreds of meters thick; in 

shallower waters with less fine sediments, it can be much thinner (only a few 

centimeters in places) or absent. Thickness is determined by substrate 

composition and current shear.
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 Neustonic Layer – Layer of biota that lives at the surface of the water. These 

organisms are either positively buoyant, maintain position by taking advantage of 

surface tension, or live on other biotic or abiotic material. Epineuston floats atop 

the water, hyponeuston lives just under the surface.

 Nutrient Maximum – A layer or region in the water column that has high 

concentrations of a particular nutrient or nutrients due either to biological 

transformation or to abiotic factors such as advection or entrainment from 

adjacent water masses.

 Nutrient Minimum – A layer in the ocean where net nutrient accumulation is at a 

minimum, often due to a locus of high biological activity drawing down nutrient 

stocks.

 Nutricline – The zone of rapid nutrient change with depth in the water column, 

often as a result of entrainment of water from a lower depth that is higher in 

concentration of a particular nutrient. The nutricline can be a rich source of a 

limiting nutrient and hence, the site of intense microbial or photosynthetic 

activity.

 Oxygen Maximum – A layer in the ocean where oxygen concentration is at a 

minimum, often due to a locus of high respiratory activity, notably microbial.

 Oxygen Minimum – Region in the water column where oxygen is reduced 

(relative to surrounding waters) due to high respiration rates, usually associated 

with high concentrations of organic matter.

 Oxycline – Zone in the water column where oxygen concentration changes 

rapidly with depth, often as a result of biological or abiotic processes that 

consume oxygen. Deep, bottom water that contains no photosynthetic 

organisms—yet receives much deposited organic matter—can generate both high 

respiration rates and extremely low oxygen concentrations. The transition layer 

between hypoxic bottom water and oxygenated surface water is the oxycline.

 Sea Foam – Sea foam is produced by turbulent mixing and agitation of surface 

waters, enhanced by high concentrations of dissolved organic matter (DOM).

 Seep – Area on the ocean bottom where fluid slowly emerges. Cold seeps are 

usually at the continental margins; waters in these seeps are often highly 

concentrated in minerals and dissolved gases, such as hydrogen sulfide, methane,

and hydrogen. Cold-fluid seeps and oil seeps are sources of energy for 

chemoautotrophic communities of bacteria and archaea, which in turn support 

communities of clams, mussels and vestimentiferan tubeworms.
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 Surface Film – Thin layer of materials and biota that exist on the surface of the 

water, often only a few microns thick. The surface film can contain a rich 

microbial community that consumes the material that concentrated in the film. 

Dissolved Organic Carbon (DOC) is concentrated up to five times in the surface 

microlayer. These films are often aggregated and concentrated at frontal 

convergences of two water masses and can lead to formation of a rich community

that feeds on the material.

 Surface Mixed Layer – The layer of water at the ocean surface that is mixed by 

wind. Water of homogeneous density is easily mixed to a depth determined by the 

intensity of wind shear and density of the water. Often wind mixing of the surface 

occurs to the pycnocline depth where density increases rapidly. The mixed layer 

depth is an important determinant of the extent and intensity of photosynthetic 

production as plankton cells are mixed through the vertical light gradient.

 Thermocline – The zone of rapid temperature change with depth in the water 

column, often separating two layers of different, homogeneous temperature. As 

the density of water changes with temperature, the thermocline presents a barrier 

to vertical circulation and enhances water column stability.

 Turbidity Maximum – Region in an estuary where turbidity is high, due to 

concentration of particulates in the water column. This occurs as a result of the

increasing ionic strength of the water from the introduction of salt in the 

downstream direction (generally at around areas with a salinity of 5), which 

causes particle aggregation. This process is enhanced by the mixing regime 

particular to this upper estuary region, in which countercurrent flows from the salt 

wedge are entrained into the seaward-flowing, upper-water layer. As particles 

settle out of the upper layer, they are carried upstream in the lower layer and so 

circulate within a zone of maximum turbidity.

5.8 Water Column Component Modifiers

A wide range of modifiers that can be used to further define the water column are 

described in Section 10. Modifiers that are particularly important and widely applied to 

the water column are listed below and further defined in Section 10.

 Physical

o Tidal Regime (amplitude)

o Wave Regime (amplitude)

 Physicochemical

o Oxygen

o Photic Quality

o Turbidity

o Turbidity Type

o Turbidity Provenance
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o Water Column Stability

 Temporal

o Temporal Persistence
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6. Geoform Component

The geomorphology of an area has a determinative influence on the character and 

stability of soil and sediment, and local topography has a powerful influence on plant and 

animal communities. In CMECS, the geological context—and associated features of the 

landscape and seascape—are captured in the Geoform Component (GC), which describes 

the physical structure of the environment across multiple scales. Geoform units provide 

structure, channel energy flows, and regulate bioenergetics. They also control such 

processes as water exchange rates and water turnover times; hydrologic and energy 

cycling; shelter and exposure to energy inputs; and migration and spawning. Because of 

these diverse interactions, it is impossible to fully understand a biotic community without 

also considering the geological context in which the organisms are found. The GC 

addresses five aspects of the coastal and seafloor morphology: tectonic setting, 

physiographic setting, geoform origin, geoform, and geoform type. The framework for 

the GC adopts most of the structures described by Greene et al. (2007) and the estuary 

types outlined in Madden et al. (2008), but expands the options to include a larger 

number of coastal and nearshore features.

The GC is not intended to be a geological classification per se. Rather, it provides a way

to present the structural aspects of the physical environment that are relevant to—and

drivers of—biological community distribution. This component does not include surface 

geology attributes [such as hardbottom, softbottom, sand, gravel, and cobble as in Greene 

et al. (2007)], because these attributes are included in the Substrate Component that 

describes the character and composition of the seafloor. Used together, geoform and 

substrate component units reflect the physical environment in which benthic/attached

biota occurs.

The GC is organized into four subcomponents that occur along a spatial continuum

(Table 6.1): tectonic setting and physiographic setting describe large, global features,

while the level 1 and level 2 geoform subcomponents describe meso- and microscale 

units (extending down to features at the meter scale). Each subcomponent has a general 

scale range associated with it, but features within these categories will naturally overlap 

one another—because of the natural gradients and transitions between geologic units and 

processes. Similarly, regional differences in processes will cause units to respond 

differently on spatial and temporal scales (Harris et al. 2005).

There are no mapping scales explicitly associated with the geoform levels. Users should 

determine a spatial scale for their work based on (a) project objectives and (b) the 

observational technologies to be employed. Users should then apply the appropriate GC 

units based on that scale; they are free to use any subcomponent singly or in combination.

Modifiers are available to further describe geoform features.

The GC features listed in this document are meant to be an initial list; they are subject to 

modification as the standard is applied over time. See Appendix D for a table of the GC 

units and Section 10 for more details on CMECS modifiers.
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Table 6.1. Geoform Component Classification Structure.

Geoform Component

Tectonic 

Setting 

Subcomponent

Physiographic

Setting 

Subcomponent

Level 1 Geoform

Subcomponent

Level 2 Geoform 

Subcomponent

List of tectonic 

settings

List of physiographic 

settings

Geoform Origin

 Level 1 Geoform

 Level 1 Geoform Type

Geoform Origin

 Level 2 Geoform

 Level 2 Geoform Type

6.1 Tectonic Setting Subcomponent

At the largest scales, the GC is divided into eight planetary features that reflect global 

tectonic processes (both past and present). Generally, these features are thousands of

square kilometers or larger in size. They include both continental and oceanic crustal 

units, and the tectonic setting features form the context for all of the smaller-scale 

geoforms.

 Abyssal Plain – A flat region of the deep ocean floor (with a slope less than 

1:1,000) that was formed by the deposition of pelagic and gravity-current

sediments, which obscure the pre-existing topography. Vast areas of the ocean 

floor fall within this setting, which can be subdivided into smaller basins based on 

regional topography.

 Convergent Active Continental Margin – Intense areas of active magmatism,

where the oceanic lithosphere is subducted beneath the continental lithosphere. 

This results in chains of volcanoes near the continental margin; the leading edge 

of the continental plate is usually studded with steep mountain ranges.

 Divergent Active Continental Margin – Areas where tensional tectonic forces 

result in the crustal rocks being stretched and–ultimately—split apart or rifted.

These areas are marked by subsidence and a continental rise. 

 Fracture Zone – An elongate zone of unusually irregular topography (on the 

deep seafloor) that often separates basins and regions of different depths; fracture 

zones commonly follow (and extend beyond) offsets of the mid-ocean ridge. 

 Spreading Center – Spreading centers are areas where tectonic plates are moving 

apart, allowing new oceanic crust to reach the surface of the sea floor.

 Mid-Ocean Ridge – An extremely large, global spreading center. The mid-ocean 

ridge is a continuous, seismically active, median mountain range extending 

through the North Atlantic, South Atlantic, Indian, and South Pacific Oceans. It is 
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a broad, fractured swell with a central rift valley and usually extremely rugged 

topography. The ridge is 1–3 kilometers in height, about 1,500 kilometers in 

width, and over 84,000 kilometers in length. Sections of this feature are 

sometimes named based on the ocean region in which this feature occur (for 

example, Mid-Atlantic Ridge).

 Passive Continental Margin – The transition between oceanic and continental 

crust that is not an active plate margin. This feature was constructed by 

sedimentation above an ancient rift, now marked by transitional crust. Major 

tectonic movement is broad, whereas regional vertical adjustment, Earthquakes,

and volcanic activity are minor and local.

 Transform Continental Margin – A feature defined by the transform fault that 

develops during continental rifting. These margins differ from rifted or passive 

margins in two key ways; they have a narrow continental shelf (less than 30

kilometers) and a steep ocean-continent transition zone (Keary et al. 2009).

 Tectonic Trench – A narrow, elongate depression of the deep seafloor associated 

with a subduction zone. These can be oriented parallel to a volcanic arc and are 

commonly aligned with the edge of the adjacent continent, between the 

continental margin and the abyssal hills. Trenches are commonly greater than 2 

kilometers deeper than the surrounding ocean floor, and they may be thousands of 

kilometers long.

6.2 Physiographic Setting Subcomponent

Spatially nested within the tectonic settings, physiographic settings describe landscapelevel geomorphological features from the coast to mid-ocean spreading centers. These 

large features—generally on the scale of hundreds of square kilometers—can cross 

tectonic settings, and they can be delineated at a scale of 1:1,000,000 (or greater) using 

bathymetric maps and other remote sensing data. Each setting will normally contain a 

wide variety of the smaller geoform features.

 Abyssal/Submarine Fan – A low, outspread, relatively flat–to-gently sloping 

mass of loose material—shaped like an open fan or a segment of a cone—

deposited by a flow of water at the place where it issues from a narrower or 

steeper-gradient area into a broader area, valley, flat, or other feature. Abyssal 

fans form at the mouths of submarine canyons, and fans are also the result of 

turbidities (that is, gravity-driven, underwater avalanches).

 Barrier Reef – A long, narrow coral reef, roughly parallel to the shore and 

separated from it by a lagoon of considerable depth and width. This reef may 

enclose a volcanic island (either wholly or in part), or it may lie a great distance 

from a continental coast (such as the Great Barrier Reef). Generally, barrier reefs 

follow the coasts for long distances—often with short interruptions that are called

passes or channels. Three principle examples of this type of feature are 
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Australia’s Great Barrier Reef, the New Caledonia Barrier Reef, and the MesoAmerican Barrier Reef system—although similar features exist elsewhere.

 Bight – A broad bend or curve in a generally open coast. Examples include the 

South Atlantic Bight and the Southern California Bight. These are distinguished 

from Embayment/Bays by the shallower angle between the apex of the bight and 

the adjacent coasts, although the term Bay has been used to name these features 

(e.g., Bay of Campeche).

 Borderland – An area of the continental margin (between the shoreline and the 

continental slope) that is topographically more complex than the continental shelf.

This feature is characterized by ridges and basins, some of which are below the 

depth of the continental shelf.

 Continental/Island Rise – An area that lies at the deepest part of a continental or 

island margin between the continental slope and the abyssal plain. The rise is a 

gentle incline (with slopes of 0.5° to 1°) and it has generally smooth 

topography—although it may bear submarine canyons.

 Continental/Island Shelf – That part of the continental margin that is between 

the shoreline and the continental slope (or a depth or 200 meters when there is no 

noticeable continental slope); it is characterized by its very gentle slope of 0.1°. 

Island shelves are analogous to the continental shelves, but surround islands.

 Continental/Island Shore Complex – This feature includes the land-water

interface zone and contains geoforms across a diversity of scales. For CMECS,

the supratidal zone forms the landward limit of geoforms found within the shore 

complex setting. This setting does not include the land-water interface along tidal 

rivers that may extend a considerable distance inland.

 Continental/Island Slope – That part of the continental margin that is between 

the continental shelf and the continental rise (if there is one); it is characterized by 

its relatively steep slope of 1.5 - 6°. Island slopes are analogous to the continental 

slopes, but occur around islands.

 Embayment/Bay – A water body with some level of enclosure by land at 

different spatial scales. These can be wide, curving indentations in the coast, arms 

of the sea, or bodies of water almost surrounded by land. These features can be 

small—with considerable freshwater and terrestrial influence—or large and 

generally oceanic in character.

 Fjord – A long, narrow, glacially eroded inlet or arm of the sea. They are often 

U-shaped, steep-walled, and deep. Because of their depth, they tend to have low 

surface-area-to-volume ratios. They have moderate watershed-to-water-area ratios 

and low-to-moderate riverine inputs. Fjords often have a geologic sill formation at 

the seaward end caused by glacial action. This morphology—combined with a 
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low exchange of bottom waters with the ocean—can result in formation of 

hypoxic bottom waters.

 Inland/Enclosed Sea – A large, water body almost completely surrounded by 

land. Salinities range from fresh through marine. The term inland is used to 

describe situations where the water body is connected to an adjacent large water 

body by a narrow strait, channel, canal, or river. Examples of this type of setting 

are the Mediterranean and Black Seas. The Great Lakes, due to their connectivity 

to the Atlantic Ocean via the St. Lawrence River also fall into this category.

 Lagoonal Estuary – This class of estuary tends to be shallow, highly enclosed, 

and have reduced exchange with the ocean. They often experience high 

evaporation, and they tend to be quiescent in terms of wind, current, and wave 

energy. Lagoonal estuaries usually have a very high surface-to-volume ratio, a 

low-to-moderate watershed-to-water-area ratio, and can have a high wetland-towater ratio. The flushing times tend to be long relative to riverine estuaries and 

embayments because the restricted exchange with the marine-end member and the 

reduced river input lengthen residence times. As such, there tends to be more 

benthic-pelagic interaction, enhanced by generally shallow bathymetry. 

Additionally, exchange with surrounding landscapes (often riparian wetland and 

palustrine systems) tends to be enhanced and more highly coupled than in other 

types of estuaries.

Occasionally, a lagoon may be produced by the temporary sealing of a river 

estuary by a barrier. Such lagoons are usually seasonal and exist until the river 

breaches the barrier; these lagoons occur in regions of low or sporadic rainfall.

 Major River Delta – The nearly flat, alluvial tract of land at the mouth of a river, 

which commonly forms a triangular or fan-shaped plain. It is crossed by many 

distributaries, and the delta is the result of sediment accumulation from the river. 

Deltas are distinguished from alluvial fans by their flatter slope. Examples of this 

feature include the Mississippi Delta, the Nile Delta, and the Ganges Delta. All 

deltas are dynamic areas of mixed-water flow and salinity.

 Marine Basin Floor – Basin floors refer broadly to the areas of the seafloor 

between the base of the continental margin (usually the foot of the continental 

rise) and the mid-ocean ridge. Occasionally, this large region is subdivided into 

smaller basins based on local bathymetry.

 Ocean Bank/Plateau – A mound-like or ridge-like elevated area on the seafloor; 

it may have a modest-to-substantial extent. Although submerged, this feature can 

reach close to sea level (e.g., Bahama Banks).

 Riverine Estuary – This class of estuary tends to be linear and seasonally turbid

(especially in upper reaches), and it can be subjected to high current speeds. 

These estuaries are sedimentary and depositional, so they may be associated with 

a delta, bar, barrier island, and other depositional features. These estuaries also 
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tend to be highly flushed (with a wide and variable salinity range) and seasonally 

stratified. Riverine estuaries have moderate surface-to-volume ratios with a high 

watershed-to-water-area ratio—and they can have very high wetland-to-waterarea ratios as well. These estuaries are often characterized by a V-shaped channel 

configuration and a salt wedge.

High inputs of land drainage can promote increased primary productivity, which

may be confined to the water column in the upper reach, due to low transparency 

in the water column. Surrounding wetlands may be extensive and healthy, given 

the sediment supply and nutrient input. This marsh perimeter may be important in 

taking up the excess nutrients that are introduced to the system. Physically, the 

system may tend to be stratified during periods of high riverine input, and the 

input of marine waters may be enhanced by countercurrent flow.

 Shelf Basin – Basins occurring on the continental shelf formed by offshore 

faulting activity.

 Shelf Break – The slope discontinuity (rapid change in gradient) of 3° or greater 

that occurs at the outer edge of the continental shelf. This boundary generally 

occurs at a depth between 100–200 meters and forms the boundary between the 

Marine Offshore and Oceanic Subsystems.

 Sound – (a) A relatively long, narrow waterway connecting two larger bodies of 

water (or two parts of the same water body), or an arm of the sea forming a 

channel between the mainland and an island (e.g., Puget Sound, WA). A sound is 

generally wider and more extensive than a strait. (b) A long, large, rather broad 

inlet of the ocean, which generally extends parallel to the coast (e.g., Long Island 

Sound, NY).

 Submarine Canyon – A general term for all linear, steep-sided valleys on the 

seafloor. These canyons can be associated with terrestrial or nearshore river 

inputs, such as in the Hudson or Mississippi canyons.

 Trench – Trenches in the physiographic setting subcomponent occur at a smaller 

spatial scale than the hemispheric-sized trenches in the tectonic setting. Both 

types of trenches share similar morphology, but physiographic setting Trenches 

are not necessarily associated with plate subduction.

6.3 Level 1 and Level 2 Geoform Subcomponent Hierarchical 

Structure

The Level 1 and Level 2 geoform subcomponents have the same structure and are 

composed of three hierarchical levels that describe the origin of the geoform (Geoform 

Origin), the geoform structure (Geoforms), and specific types of geoforms (Geoform 

Type).
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Geoform Origin

With the exception of major barrier reef complexes (e.g., the Great Barrier Reef), the 

tectonic and physiographic setting units are the result of geologic activity and physical 

processes. Geoforms, on the other hand, are spatially smaller and can be created by a 

variety of means, which are important to understanding their history and ecology. In 

CMECS, the three major geoform origin types—geologic, biogenic, and anthropogenic—

are based on the processes that created the physical features reflected in the geoform 

units. Note that (a) a designation of biologic geoform does not infer the presence of living 

biota (which is captured in the Biotic Component) and (b) anthropogenic geoforms do not 

imply any particular human use at the time of observation.

6.3.1 Level 1 and Level 2 Geoforms

Geoforms are physical, coastal and seafloor structures that are generally no larger than 

hundreds of square kilometersin size. This size determination may be an areal extent or a 

linear distance. Larger geoforms (Level 1) are generally larger than one square kilometer,

and correspond to Megahabitats in the Greene et al. classification system (2007). These 

features can be defined using geologic or geomorphic maps and bathymetric images of 

the seafloor at map scales of 1:250,000 or less. Smaller geoforms (Level 2) are generally

less than one square kilometer in size (or less than 1 kilometer in distance); and 

correspond to Meso- and Macro-habitats in the Greene et al. system. Level 2 geoforms 

(such as individual coral reefs, tide pools, and sand wave fields) can be identified through 

in-situ observational methods (such as underwater videography) or through low-altitude,

high-resolution optical or acoustic remote sensing.

Level 1 and Level 2 geoforms are arranged as two separate subcomponents so that they 

can be used in tandem to describe complex spatial patterns of geoform structures. Level 2 

geoforms normally occur as portions of—or smaller features contained (nesting) within—

Level 1 geoforms, but are not hierarchically constrained by the Level 1 geoforms. It is 

possible for geoforms at either level to nest within other units within their same level (for 

example, a Level 2 pockmark may occur within a Level 2 shoal/bar as in Figure 6.1

below).

6.3.2 Geoform Types

Geoform types are varieties of geoforms that provide further information on morphology 

and physical processes underway at any individual geoform. Users are encouraged to 

apply the Type designations where applicable—but they are not required to use it if their 

data do not support this level of detail. Users are also encouraged to provide the full 

nesting (recording of upper-level attributes) for any geoforms they identify, although 

there will be many instances where this is not practical.
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Figure 6.1. Level 2 Pockmarks Occurring on a Small, Level 2 Tidal Flat.

6.4 Level 1 and Level 2 Geoform Units

Although Level 1 and Level 2 geoforms are considered different subcomponents because 

of their scale differences, they share the same hierarchical structure and some units are 

found in both levels (if they occur over a broad range of sizes). For brevity, we have 

combined the definitions of these units into one listing and have indicated the 

subcomponent(s) in which they reside.

Geoform Origin: Geologic

Geologic geoforms are formed by the abiotic processes of uplift, erosion, volcanism, 

deposition, fluid seepage, and material movement. Uplift may be a result of local and 

regional seismic and tectonic processes. Waves, currents, wind, chemical dissolution, 

seismic motion, and chemical precipitation all contribute to these geoforms and give 

them their distinctive qualities. 

 Geoform: Apron (Level 1) – An extensive, subaqueous, blanket-like deposit of 

alluvial, unconsolidated material that is derived from an identifiable source and 

deposited at the base of a mountain or seamount.

 Geoform: Bank (Level 1) – An elevated area above the surrounding seafloor that 

rises near the surface. Banks generally are low-relief features, of modest-tosubstantial extent, that normally remain submerged. They may have a variety of 

shapes and may show signs of erosion resulting from exposure during periods of 

lower sea level. Banks tend to occur on the continental shelf. Banks differ from 

shoals in having greater size and temporal persistence. The Geoform Bank 

differs from the Coral Reef Zone modifier Bank based on its geologic origin.
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 Geoform: Bar (Levels 1 & 2) – A relatively shallow place (in a stream, lake, sea, 

or other body of water) that is typically a submerged ridge, or bank consisting of 

(or covered) by sand or other unconsolidated material—but may also be 

composed of rock or other material (modified from Jackson 1997).

o Geoform Type: Bay Mouth Bar (Level 1 only) – A bar of sand or 

gravel extending partially or entirely across the mouth of a bay. It 

usually connects two headlands, thus straightening the coast.

o Geoform Type: Longshore Bar (Level 1 only) – A low sand ridge, 

built chiefly by wave action, occurring at some distance from and 

generally parallel with the shoreline, being submerged at least by high 

tides, and typically separated from the beach by an intervening trough.

o Geoform Type: Point Bar (Level 2 only) – Low, arcuate, subaerial 

ridges of sand developed adjacent to an inlet and formed by the lateral 

accretion or movement of the channel.

o Geoform Type: Relict Longshore Bar (Level 2 only) – A narrow, 

elongate, coarse-textured ridge that once rose near to, or barely above, 

a pluvial or glacial lake or other body of water and extended generally 

parallel to the shore but was separated from it by an intervening trough 

or lagoon; both the bar and lagoon are now relict features (Jackson 

1997).

 Geoform: Basin (Level 1) – General term for an area of the seafloor or land 

surface that lies below the surrounding bottom or terrain elevation. They are 

normally areas of low relief.

 Geoform: Beach (Levels 1 & 2) – A gently sloping zone formed by 

unconsolidated material at the shoreline, typically with a concave profile. This 

zone extends landward from the low-water line to either (a) the place where there 

is a definite change in material or physiographic form (such as a cliff) or (b) the 

line of permanent vegetation. Only those portions of the beach within the splash 

zone would be within the CMECS system; areas of the beach further inland are 

terrestrial systems.

o Geoform Type: Barrier Beach (Levels 1 & 2) – A narrow, elongate, 

coarse-textured, intertidal, sloping landform that is generally parallel 

with the beach ridge component of the barrier island (or a spit), and 

which is adjacent to the ocean (Jackson 1997; Peterson 1981).

o Geoform Type: Mainland Beach (Levels 1 & 2) –Any beach that is

connected to the mainland, whether fronting bluffs, dunes, or extensive 

marshes.
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o Geoform Type: Pocket Beach (Level 2 only) – A small beach 

between two headlands. Because of this isolation, there is very little—

or no—exchange of sediment between the pocket beach and the 

adjacent shorelines.

o Geoform Type: Tide-Modified Beach (Levels 1 & 2) – Beaches that 

occur in areas of high tide range (3–15 times the wave height) and 

usually lower waves (less than 0.3 meter). Tide-modified beaches

include reflective beaches with a low-tide terrace, reflective beaches 

with bars and rips, and ultra dissipative beaches.

o Geoform Type: Tide-Dominated Beach (Levels 1 & 2) – Beaches 

that occur in areas of high tide range (10–15 times the wave height) 

and usually lower waves; wave height is very low. Tide-dominated 

beaches include reflective beaches with sand ridges, reflective beaches

with sand flats, reflective beaches with tidal sand flats, reflective 

beaches with tidal mud flats, and reflective beaches with rock flats.

o Geoform Type: Wave-Dominated Beach (Levels 1 & 2) – Beaches 

that are exposed to persistent ocean swell, waves, and low tides (range 

of less than 2 meters). Wave-dominated beaches include reflective

beaches, intermediate beaches, and dissipative beaches (Short 2006).

 Geoform: Beach Berm (Levels 1 & 2) – The natural bench or platform lying 

below the main beach slope and above the foreshore.

 Geoform: Boulder Field (Level 1) – An area dominated by large, boulder-sized

(256 millimeters – 4,096 millimeters) stones or pieces of rock. These can occur 

below cliffs or at the foot of steep slopes or canyons, where they are the result of 

depositional processes. These fields can also occur as the result of currents that 

have removed the finer sediments.

 Geoform: Cave (Level 2) – A natural passage extending beneath the Earth’s 

surface.

 Geoform: Channel (Levels 1 & 2) – A general term for a linear or sinuous 

depression on an otherwise more flat area (for example, a valley- or groove-like 

feature through which water flows). This is a very broad term that is often used in 

connection with other terms to provide more meaning.

o Geoform Type: Pass/Lagoon Channel (Level 2 only) – A generally 

narrow passage way, open on both ends, through a shoal. In coral reef 

settings this feature connects the lagoon with the open ocean or bay.

o Geoform Type: Sand Channel (Level 2 only) –These are narrow 

passages between, and in association with, pavement formations 

commonly oriented perpendicular to the shore. The bottoms of these 
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channels normally consist of sand or other unconsolidated mineral 

substrates. They occur in areas of moderate wave surge and have low 

vertical relief as compared to spur-and-groove formations.

o Geoform Type: Slough (Level 1) – (a) A sluggish body of water in a 

tidal flat, bottomland, or coastal marshland; may also be called bayous 

or oxbows. (b) A sluggish channel of water (such as a side channel of 

a river) in which water flows slowly through either low, swampy 

ground (such as along the Columbia River) or a section of an 

abandoned river channel (which may contain stagnant water) that

occurs in a flood plain or delta.

o Geoform Type: Tidal Channel/Creek (Levels 1 & 2) – Linear or 

sinuous body of water through which ebb-and-flood tidal movement 

takes place. Smaller tidal creeks often branch off of these features. 

Portions of tidal channels may be intertidal or completely subtidal.

 Geoform: Cone (Levels 1 & 2) – (a) A type of submarine, fan-shaped deposit—

especially a deep-sea fan associated with a major active delta (such as deltas of 

the Mississippi, Nile, and Ganges Rivers). (b) A formation resulting from the 

extrusion of material onto the surrounding seabed (e.g., a volcanic cone).

 Geoform: Cove (Levels 1 & 2) – A small, narrow, sheltered bay or recess in an 

estuary; often found inside a larger embayment (modified from Jackson 1997).

o Geoform Type: Barrier Cove (Levels 1 & 2) – A subaqueous area 

adjacent to a barrier island (or submerged barrier beach) that forms a 

minor embayment or cove within the larger basin.

o Geoform Type: Mainland Cove (Levels 1 & 2) – Small embayment 

or narrow indentation in a mainland coast. These coves usually have 

narrow entrances and are circular or oval in shape.

 Geoform: Delta (Levels 1 & 2) – The low, nearly flat, alluvial tract of land at (or 

near) the mouth of a river. Deltas commonly form a triangular or fan-shaped plain 

of considerable area, which is crossed by many distributaries of the main river;

deltas may extend beyond the general trend of the coast, and occur as a result of 

the accumulation of river sediment supplied in such quantities that it is not 

removed by tides, waves, and currents.

o Geoform Type: Glacial (Kame) Delta (Level 1 only) – A landform

made by a stream flowing through glacial ice and then depositing

material as it enters a lake or pond at the end (or terminus) of the 

glacier. This delta is distinctive because it has been sorted by the 

action of the stream. This landform may often be observed after the 

glacier has melted. As the glacier melts, the edges of the delta may 

subside (as ice under it melts); additionally, glacial till may be 
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deposited in the lateral or side area of the delta from the melting 

glacier.

o Geoform Type: Ebb Tidal Delta (Level 2 only) – A largely 

subaqueous (although sometimes intertidal), crudely fan-shaped delta 

with sand-sized sediment, which has been formed on the seaward side 

of a tidal inlet (modified from Boothroyd et al. 1985; Davis 1994;

Ritter, Kochel, and Miller 1995).

o Geoform Type: Flood Tidal Delta (Level 2) – Equivalent to an Ebb 

Tidal Delta, except that this delta occurs on the landward side of a tidal 

inlet (modified from Boothroyd et al. 1985; Davis 1994; Ritter et al.

1995). Flood tides transport sediment through the tidal inlet, over a 

flood ramp where currents slow and dissipate before entering the 

lagoon (Davis 1994). Generally, flood tidal deltas along microtidal 

coasts are multi-lobate and unaffected by ebbing currents (modified 

from Davis 1994).

o Geoform Type: Flood Tidal Delta Slope (Level 2 only) – The 

sloping surfaces found at the edge of the tidal delta.

o Geoform Type: Levee Delta (Levels 1 & 2) – A delta having the 

form of a long, narrow ridge that resembles a natural levee.

 Geoform: Delta Plain (Level 1 only) – The level (or nearly level) surface that 

makes up the landward part of a large delta; strictly, a flood plain characterized by 

repeated channel bifurcation and divergence, multiple distributary channels, and 

interdistributary flood basins.

 Geoform: Depression (Level 2) – General term for any relatively sunken part of 

the Earth’s surface—especially a low-lying area surrounded by higher ground. 

Depressions often have no natural outlet for surface drainage (such as an interior 

basin or a karstic sinkhole) (Jackson 1997).

o Geoform Type: Scour Depression (Level 2 only) – Depression 

formed by the abrasive action of sand or sediment driven by the 

movement of water or ice.

 Geoform: Diapir (Levels 1 & 2) – A dome or anticlinal fold in which the 

overlying rocks or sediments have been ruptured when the plastic core material 

was squeezed out. Diapirs in sedimentary strata usually contain cores of salt or 

shale; igneous intrusions may also show diapiric structure.

o Geoform Type: Salt Dome (Levels 1 and 2) – A diaper formed by 

the intrusion of salt into surrounding rocks.

 Geoform: Dike (Level 2) – A tabular, igneous intrusion that cuts across the 

bedding or foliation of the country rock. Dikes are often more resistant to erosion

than the surrounding country rock, and dikes can form long ridges.
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 Geoform: Drumlin Field (Level 1) – Groups or clusters of closely spaced 

drumlins or drumlinoid ridges, distributed more or less en echelon, and commonly 

separated by small, marshy tracts or depressions (interdrumlins).

 Geoform: Drumlin (Level 2) – Drumlins are products of the streamline (laminar) 

flow of glaciers, which molded the subglacial floor through a combination of 

erosion and deposition. A drumlin is a low, smooth, elongated-oval hill, mound, 

or ridge of compact till, which has a core of bedrock or drift. A drumlin usually 

has a blunt nose facing the direction from which the ice approached, and a gentler 

slope tapering in the other direction. The longest axis is parallel to the general 

direction of glacier flow. 

 Geoform: Dune Field (Level 1) – An assemblage of moving and/or stabilized 

dunes; sand plains; interdune areas; and the ponds, lakes, or swamps produced by 

the blocking of waterways by migrating dunes (U.S. Department of Agriculture

2008).

 Geoform: Dune (Level 2) – An active accumulation of sand (formed by wind 

action) with some elevation; dunes occur on a beach or further inland.

 Geoform: Fan (Levels 1 & 2) – A low, outspread gently to steeply sloping mass 

of loose material, which is shaped like an open fan or a segment of a cone. Fans 

are made of material deposited by a flow of water at the place where it issues 

from a narrower or steeper gradient area into a broader area, valley, flat, or other 

feature.

o Geoform Type: Alluvial Fan (Level 1 only) – A low, outspread, 

relatively flat (or gently sloping) mass of loose rock material, shaped 

like an open fan or a segment of a cone. The rock material was 

deposited by flowing water where it issues from a narrow valley or 

where the gradient abruptly changes. Alluvial fans are usually steeper 

than the surrounding surface.

o Geoform Type: Basin Floor Fan (Level 1 only) – Deposition of 

submarine fans on the lower slope or basin floor; fan formation is 

associated with the erosion of canyons into the slope and the incision 

of fluvial valleys into the shelf. Siliciclastic sediment bypasses the 

shelf and slope through the valleys and canyons to feed the basin floor 

fan; sediment may be deposited at the mouth of a canyon or in an area

widely separated from the canyon mouth—or a canyon may not be 

evident.

o Geoform Type: Shoreline Fan (Level 1 only) – A prograding 

shoreline formed where an alluvial fan is built out into a lake or sea.

o Geoform Type: Washover Fan (Levels 1 & 2) – A fan-like landform 

of sand that washed over a barrier island or spit during a storm, and 

then deposited sand on the landward side. Washover fans can be small 
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and completely subaerial—or they can be quite large and include 

subaqueous margins that extend into adjacent lagoons or estuaries. 

Large fans can composed of ephemeral washover channels (micro 

feature) cut through dunes or beach ridges, back barrier flats, 

(subaqueous) washover fan flats, and (subaqueous) washover fan 

slopes. Subaerial or intertidal portions can range from barren to 

completely vegetated (U.S. Department of Agriculture 2008).

 Geoform: Flat (Levels 1 & 2) – A general term for a level (or nearly level)

surface or area of land marked by little or no relief; flats are often composed of 

unconsolidated sediments (such as mud or sand). These forms are more 

commonly encountered in the intertidal or in the shallow subtidal zones (see 

Figure 6.2).

o Geoform Type: Back Barrier Flat (Level 1 only) – A subaerial, 

gently sloping landform on the lagoon side of the barrier beach ridge. 

These flats are composed predominantly of sand washed over (or 

through) the beach ridge during tidal surges (modified from Jackson 

1997).

o Geoform Type: Barrier Flat (Level 1 only) – A relatively flat, lowlying area that is separating the exposed (or seaward) edge of a barrier 

beach or barrier island from the lagoon behind it. Barrier flats 

commonly include pools of water, and may be barren or vegetated. 

These flats are an assemblage of both deflation flats left behind 

migrating dunes and/or storm washover sediments.

o Geoform Type: Ebb Tidal Delta Flat (Level 2 only) – The relatively 

flat, dominant component of the ebb tidal delta. At extreme low tide,

this landform may be exposed for a relatively short period (U.S. 

Department of Agriculture 2008).

o Geoform Type: Flood Tidal Delta Flat (Level 2 only) – The 

relatively flat, dominant component of the flood tidal delta. At extreme 

low tide, this landform may be exposed for a relatively short period 

(U.S. Department of Agriculture 2008).

o Geoform Type: Tidal Flat (Levels 1 & 2) – An extensive, nearly 

horizontal, barren (or sparsely vegetated) tract of land that is 

alternately covered and uncovered by the tide. Tidal flats consist of 

unconsolidated sediment (mostly clays, silts and/or sand, and organic 

materials).

o Geoform Type: Washover Fan Flat (Level 1 only) – A gently 

sloping, fan-like, subaqueous landform created by overwash from 

storm surges that transports sediment from the seaward side to the 

landward side of a barrier island (Jackson 1997). Sediment is carried 

through temporary overwash channels that cut through the dune 

complex on the barrier spit (Fisher and Simpson 1979; Boothroyd et 
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al. 1985; Davis 1994) and spill out onto the lagoon-side platform,

where they coalesce to form a broad belt. Also called Storm-Surge 

Platform Flat (Boothroyd et al. 1985) and Washover Fan Apron 

(Jackson 1997).

o Geoform Type: Wind Tidal Flat (Level 1 only) – A broad, lowlying, nearly level sand flat that is alternately flooded by ponded 

rainwater or inundated by wind-driven marine and estuarine waters. 

Salinity fluctuations and prolonged periods of exposure preclude 

establishment of most types of vegetation (except for mats of 

filamentous blue-green algae).

Figure 6.2. Wind Tidal Flat: Lower Laguna Madre, Texas.

 Geoform: Fluvio-Marine Deposit (Levels 1 & 2) – Stratified materials (clay, 

silt, sand, or gravel) formed by both marine and fluvial processes, resulting from 

non-tidal sea-level fluctuations, subsidence, and/or stream migration (e.g.,

materials originally deposited in a nearshore environment and subsequently 

reworked by fluvial processes as the sea level fell).

 Geoform: Fracture (Levels 1 & 2) – A crack or split formed in a rock or 

bedrock as a result of local erosion or rock stress; they are not due to tectonic 

actions (which form larger faults and fracture zones).

 Geoform: Hole/Pit (Level 2) – A generally more steep- sided indentation or 

depression that is lower than the surrounding surface formed through a variety of 

processes.
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o Geoform Type: Scour Hole (Level 2 only) – A hole formed by the 

powerful and concentrated clearing and digging action of flowing air, 

water, or ice—especially the downward erosion by stream water (in 

sweeping away mud and silt on the outside curve of a bend) or during 

the time of a flood.

o Geoform Type: Solution Hole/Pit (Level 2 only) – An indentation 

formed on a rock surface by a solution.

 Geoform: Hydrothermal Vent Field (Levels 1 & 2) – An area where several 

hydrothermal vents, either active or inactive, are present.

 Geoform: Hydrothermal Vent (Level 2) – Structures on the seafloor through 

which materials related to volcanic activity are extruded. These often form tall, 

chimney-like structures and can support diverse chemosynthetic biota and 

associated communities.

 Geoform: Inlet (Levels 1 & 2) – Inlets are narrow constrictions through which 

water flows. The term is commonly used to describe gaps between barrier islands 

that allow tidal exchange with the adjacent—more enclosed—bays, lagoons, or 

marshes.

o Geoform Type: Tidal Inlet (Level 1 only) – Any inlet through which 

water alternately floods landward, with the rising tide, and ebbs 

seaward, with the falling tide (Jackson 1997).

o Geoform Type: Relict Tidal Inlet (Level 1 only) – A channel 

remnant that is left from a former tidal inlet. The channel was cut off 

or abandoned by infilling from migrating shore sediments.

 Geoform: Island (Levels 1 & 2) – An area of land completely surrounded by 

water—or an elevated area of land surrounded by swamp or marsh, which is 

isolated at high water or during floods.

o Geoform Type: Barrier Island (Levels 1 & 2) – A long, narrow, 

sandy island that is above high tide and parallel to the shore. Barrier 

islands commonly have dunes, vegetated zones, and swampy or 

marshy terrains extending lagoon-ward from the beach.

 Geoform: Karren (Level 2) – Repeating, surficial solution channels, grooves, or 

other forms that are etched onto massive, bare limestone surfaces; types range in 

depth from a few millimeters up to one meter, and they are separated by ridges 

May also refer to the total complex (all varieties) of surficial solution forms found 

on compact, pure limestone (U.S. Department of Agriculture 2008).

 Geoform: Knob (Level 2) – A rounded protuberance, usually prominent or 

isolated with steep sides; also including peaks or other projections from 

seamounts, or a groups of boulders, or other protruding areas of resistant rocks
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 Geoform: Lagoon (Levels 1 & 2) – Lagoons tend to be shallow, highly enclosed, 

with reduced exchange with the ocean, often experiencing high evaporation, and 

quiescent in terms of wind, current, and wave energy. They tend to have a very 

high surface to volume ratio, low to moderate watershed to water area ratio and 

can have a high wetland to water ratio. The flushing times tend to be long relative 

to riverine estuaries and even embayments, as the restricted exchange with the 

marine end member and reduced river input lengthen residence times.

 Geoform: Lava Field/Plain (Level 1) – A relatively well-defined area that is 

covered by lava flows. These can be found either along the coast or in deeper 

water. Terrain in lava fields can be rough and broken or it can be relatively 

smooth; the terrain can also include vent structures (e.g., small cinder cones or

spatter cones), surface flow structures (e.g., pressure ridges or tumuli), and small, 

intermittent areas covered with pyroclastics.

 Geoform: Ledge (Levels 1 & 2) – Bedding planes that are exposed (either on the 

surface or at depth) often form ledges that have a high habitat value and support 

colonizing plants and animals. Ledges often provide a more level surface than the 

bounding slopes. Ledges in the intertidal zone can form shelves or projections of 

rock (that are much longer than they are wide) on a rock wall or cliff face. They 

are formed along a coast by differential wave action on softer rocks and may be 

eroded by biological and chemical weathering.

 Geoform: Marine Lake (Level 1) – An inland body of permanently standing 

brackish or saline water whose water level is commonly influenced by ocean tides 

through subterranean cavities connecting to nearby lagoons. The lake is generally 

of appreciable size (larger than a pond) and too deep to permit emergent 

vegetation to take root completely across the expanse of water. Such water bodies 

can have unique biota (e.g., the stingless jellyfish of Palau).

 Geoform: Marsh Platform (Levels 1 & 2) – The flat, often thick, accumulation 

of peat that supports emergent marsh vegetation. It is commonly dissected by tidal 

creeks, and it is occasionally buried and re-exposed through the action of beach 

erosion and new inlet development.

 Geoform: Megaripples (Level 1) – Large, sand waves or ripple-like features 

having wavelengths greater than 1 meter or a ripple height greater than 10 

centimeters; Megaripples are formed in a subaqueous environment, and they are 

also known as subaqueous dunes. They may be superimposed with smaller 

bedforms (Bates and Jackson 1984).

 Geoform: Moraine (Level 1) – A mound, ridge, or other distinct accumulation of 

unsorted, unstratified, glacial drift (predominantly till) that is deposited chiefly by 

direct action of glacier ice.
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o Geoform Type: Disintegration Moraine (Level 1) – A drift 

topography characterized by chaotic mounds and pits (generally 

randomly oriented) developed in supraglacial drift by collapse and 

flow as the underlying stagnant ice melted. Slopes may be steep and 

unstable, and there will be used and unused stream courses and lake 

depressions interspersed with the morainic ridges. Characteristically, 

there are numerous abrupt changes (lateral and vertical) between 

unconsolidated materials of differing lithology.

o Geoform Type: End Moraine (Level 1) – A ridge-like accumulation 

that is being (or was) produced at the outer margin of an actively 

flowing glacier at any given time; a moraine that has been deposited at 

the outer or lower end of a valley glacier.

o Geoform Type: Ground Moraine (Level 1) – An extensive, lowrelief area of till, that has an uneven or undulating surface and is 

commonly bounded on the distal end by a recessional or end moraine.

Ground moraines usually consist of poorly sorted rock and mineral 

debris (till), which has been dragged along, in, on, or beneath a glacier,

and then deposited by basal lodgment and release from downwasting 

stagnant ice by ablation.

o Geoform Type: Kame Moraine (Level 1) – An end moraine that 

contains numerous kames, commonly comprising the slumped or 

erosional remnants of a formerly continuous outwash plain that built 

up over the foot of rapidly wasting or stagnant ice.

o Geoform Type: Lateral Moraine (Level 1) – A ridge-like moraine 

carried on (and deposited at) the side margin of a valley glacier. It is 

composed chiefly of rock fragments derived from valley walls by 

either glacial abrasion and plucking or colluvial accumulation from 

adjacent slopes.

o Geoform Type: Recessional Moraine (Level 1) – An end or lateral 

moraine, built during a temporary—but significant—halt in the final 

retreat of a glacier. May also refer to a moraine built during a minor 

re-advance of the ice front during a period of general recession.

o Geoform Type: Terminal Moraine (Level 1) – An end moraine that 

marks the farthest advance of a glacier; usually has the form of a 

massive arcuate or concentric ridge (or complex of ridges) underlain 

by till and other drift types.

 Geoform: Mound/Hummock (Levels 1 & 2) – A low, rounded, natural hill of 

unspecified origin, which is generally less than 3 meters high and composed of 

Earthy material.

o Geoform Type: Tar Mound (Level 2 only) – A mound of extruded 

tar (or other viscous hydrocarbons) on the seafloor that has some relief 

above the surrounding bottom. Tar mounds in southern California are 
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typically 10 - 100 meters in diameter and can coalesce to form tar 

reefs. Over time, tar mounds can come to support a diversity of 

colonizing organisms (Lorenson et al. 2009).

 Geoform: Mud Volcano (Level 2) – An accumulation (usually conical in shape)

of mud and rock formed by volcanic gases; may also refer to a similar 

accumulation formed by escaping petroliferous gases (Bates and Jackson 1984)

(see Figure 6.3).

Figure 6.3. Mud Volcano.

 Geoform: Natural Levee (Level 1) – An embankment of sediment, bordering 

one or both sides of a submarine canyon, fan valley, deep-sea channel, river, or 

other feature. A natural levee has a long, broad, low shape and is composed of 

sand and coarse silt, which was built by a stream on its flood plain and along both 

sides of its channel—especially in time of flood when water overflowing the 

normal banks is forced to deposit the coarsest part of its load. It has a gentle slope 

away from the river and toward the surrounding floodplain, and its highest 

elevation is closest to the river bank.

o Geoform Type: Lava Levee (Level 1) – The scoriaceous sheets of 

lava that overflowed their natural channels and solidified to form a 

levee, similar to levees formed by an overflowing stream of water.

 Geoform: Overhang (Cliff) (Levels 1 & 2) – A rock mass jutting out from a 

slope, especially the upper part or edge of an eroded cliff projecting out over the 

lower, undercut part (as above a wave-cut notch). Generally these are 

characterized as having a slope greater than 90 degrees.
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 Geoform: Panne (Level 2) – Shallow depressions or flats, often occurring in and 

adjacent to marshes in the high intertidal that zone that receive saltwater inflow 

on an infrequent basis. They often are unvegetated and can have encrustations of 

salt left by evaporation.

 Geoform: Pavement Area (Levels 1 & 2) – Flat (or gently sloping), low-relief,

solid, carbonate rock with little or no fine-scale rugosity. These areas can be 

covered with algae, hard coral, gorgonians, zooanthids, or other sessile 

vertebrates; the coverage may be dense enough to partially obscure the underlying 

surface. On less colonized pavement features, rock may be covered by a thin sand 

veneer (Kendall et al. 2001).

 Geoform: Platform (Levels 1 & 2) – Any level or nearly level surface, ranging 

in size from a terrace or bench to a plateau defined by slopes around its edges.

o Geoform Type: Wave-Cut Platform (Level 1 only) – A gently 

sloping surface produced by wave erosion, which extends into the sea 

or lake from the base of the wave-cut cliff. When subaqueous, they are

relict, erosional landforms that originally formed as a wave-cut bench 

and abrasion platform (from coastal wave erosion), which were later 

submerged by rising sea level or subsiding land surface (modified 

from Jackson 1997).

 Geoform: Pockmark Field (Level 1) – An area of the seafloor dominated by

many pockmarks.

 Geoform: Pockmark (Level 2) – Small craters in the seabed caused by fluids 

(gas and liquids) erupting and streaming through the sediments. Some pockmarks 

discovered off Nova Scotia have been up to 150 meters in diameter and 10 meters

deep.

 Geoform: Ridge (Levels 1 & 2) – A long, narrow elevation, usually sharp 

crested with steep sides. Larger ridges can form an extended upland between 

valleys.

o Geoform Type: Beach Ridge (Levels 1 & 2) – A low, essentially 

continuous mound of beach (or beach-and-dune material) heaped up 

by the action of waves and currents on the backshore of a beach, 

beyond the present limit of storm waves or the reach of ordinary tides.

The ridge can occur singly or as one of a series of approximately 

parallel deposits. The ridges are roughly parallel to the shoreline and 

represent successive positions of an advancing shoreline.

o Geoform Type: Esker (Levels 1 & 2) – A long, narrow, sinuous, 

steep-sided ridge composed of irregularly stratified sand and gravel 

that was deposited as the bed of a stream flowing in a subglacial ice 

tunnel (within or below the ice) or between ice walls on top of the ice 
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of a wasting glacier. Eskers remain behind as high ground when the 

glacier melts. Eskers range in length from less than a kilometer to 

more than 160 kilometers, and the height range is 3 - 30 meters.

 Geoform: Ripples (Level 2) – Small, linear structures that form as a result of 

water movement over unconsolidated sediments. The shape and pattern of the 

ripples provide indications of the general water movement regime in the area.

Ripples can be straight, sinuous, catenary, or linguoid.

 Geoform: Rock Outcrop (Levels 1 & 2) – An area where bedrock is exposed at 

the Earth’s surface.

o Geoform Type: Authigenic Carbonate Outcrop (Level 2 only) –

These outcrops result from the slow seepage of fluid containing 

dissolved carbon. They form pavements, chimneys, and rings, donuts, 

or slabs (Stakes et al. 1999).

 Geoform: Rubble Field (Level 1) – A loose mass of angular rock fragments. 

These can occur both on land and underwater.

 Geoform: Runnel/Rill (Level 2) – A small, transient channel carrying the water 

of a wave after it breaks on a beach. They can also be formed by tidal ebb or 

runoff (following moderate rains or ice/snow melts). Larger runnels can have 

steep sides.

 Geoform: Sediment Wave Field (Levels 1 & 2) – An area of wave-like 

bedforms in sand or other unconsolidated material which are formed by the action 

of tides, currents, or waves. These bedforms range from centimeters to meters in 

size and may be superimposed on larger features. Sand waves lack the deep scour 

associated with dunes or megaripples (Bates and Jackson 1984).

 Geoform: Scarp/Wall (Levels 1 & 2) – A relatively straight, cliff-like face or 

slope of considerable linear extent, which breaks up the general continuity of the 

land by separating surfaces lying at different levels (as along the margin of a 

plateau or mesa).

The term wall can be applied to steep or vertical areas on the seaward or exposed 

side of a reef. Although hard corals may be present, walls in this setting are 

formed by geologic processes and are not the result of reef-building activities by 

corals. A wall may be vertical or terraced, and is often referred to as the “dropoff.”

o Geoform Type: Fault Scarp (Levels 1 & 2) – A feature caused by the 

rapid erosion of soft rock on the side of a fault (as compared to that of 

more resistant rock on the other side), for example, the east face of the 

Sierra Nevada in California.
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o Geoform Type: Erosion Scarp (Levels 1 & 2) – A long, steep slope or 

line of cliffs at the edge of a plateau or ridge formed by erosion.

o Geoform Type: Beach Scarp (Levels 1 & 2) – An almost vertical slope 

(caused by wave erosion) that fronts a berm on a beach. Scarps may range 

in height from several centimeters to a few meters, depending on the 

character of the wave action and the nature and composition of the beach.

 Geoform: Scar (Levels 1 & 2) – A scar can be either a gouge or deformation of 

the bottom, or an area where the surface of the substrate, vegetation, or other 

colonizing organisms have been removed by abrasion or impact. These may be 

temporary or permanent features.

o Geoform Type: Iceberg Scour Scar/Furrow (Levels 1 & 2) – A scar 

formed by an iceberg dragging across the substrate. These can occur in 

shallow water and extend for long distances.

o Geoform Type: Slump Scar (Levels 1 & 2) – A scar formed by the 

removal of surface sediment as a result of mass wasting. These scars 

have the appearance of fresh, unweathered, or colonized sediment.

 Geoform: Seamount (Level 1) – An elevation of the seafloor, which is 1,000 

meters or higher. Seamounts may be discrete, arranged in a linear or random 

grouping, or connected at their bases and aligned along a ridge or rise.

o Geoform Type: Guyot (Level 1) – A type of seamount that has a flat 

top.

o Geoform Type: Knoll Seamount (Level 1) – A submerged elevation 

of rounded shape that rises from the ocean floor, but is less prominent 

than a seamount.

o Geoform Type: Pinnacle Seamount (Level 1) – A steep-sided, often 

isolated peak that can occur at depth or reach close to the surface. 

They are often important aggregation points for fish and other marine 

life.

 Geoform: Sediment Sheet (Level 2) – A thin, widespread, sedimentary deposit, 

formed by a transgressive sea advancing for a considerable distance over a stable 

shelf area; may also be called a blanket deposit (Bates and Jackson 1984).

 Geoform: Shelf Valley (Level 1) – A valley crossing the continental shelf, often 

forming an extension of an existing terrestrial river and terminating in a canyon as 

the valley reaches the shelf break. Shelf valleys were formed during periods of 

lower sea level, and continental, glacial melt water contributed to their genesis.

 Geoform: Shoal (Levels 1 & 2) – A relatively shallow area in a body of water 

that rises very close to, or reaches, the surface. Shoals have a variety of shapes 

that are influenced by tidal and river currents. They tend to consist of (or be 
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covered by) sand or other unconsolidated sediments, but may also be composed of 

rock or other materials. Unlike banks, shoals can be exposed during low tide or 

periods of low water flow in rivers or streams (modified from Jackson 1997). 

o Geoform Type: Moraine Shoal (Levels 1 & 2) – The submerged 

portion of a glacial moraine that reaches close to the surface. These 

often occur where sea-level rise has drowned former terrestrial glacial 

features.

 Geoform: Shore Complex (Level 1) – Generally a narrow, elongate area that 

parallels a coastline—commonly cutting across diverse inland landforms. Shore

complexes are dominated by landforms derived from active coastal processes that

give rise to beach ridges, washover fans, beaches, dunes, wave-cut platforms,

barrier islands, cliffs, etc. (Schoeneberger and Wysocki 2005).

 Geoform: Shore (Levels 1 & 2) – The intersection of a specified plane of water 

with the beach that migrates with changes of the tide or of the water level.

o Geoform Type: Foreshore (Levels 1 & 2) – The zone of the shore or 

beach that is regularly covered and uncovered by the rise and fall of 

the tide.

o Geoform Type: Backshore (Levels 1 & 2) – The upper or inner zone 

of the shore or beach that is above the high-water line of mean spring 

tides and below the upper limit of shore-zone processes. The 

backshore is usually dry or moistened by spray, and is acted upon by 

waves (or covered by water) only during exceptionally severe storms 

or unusually high tides. It is essentially horizontal or slopes gently 

landward, and it is divided from the foreshore by the crest of the most 

seaward berm.

 Geoform: Slope (Levels 1 & 2) – An inclined area of ground or substrate with a 

change in depth or elevation between its upper and lower limits. Slopes occur at 

all scales and can refer to broad areas of inclined topography to the flanks of 

small mounds or depressions in the Earth’s surface.

o Geoform Type: Washover Fan Slope (Level 1 only) – A subaqueous 

extension of a washover fan flat, which slopes toward deeper water of 

a lagoon or estuary and away from the washover fan flat.

 Geoform: Spit (Level 1) – (a) A small point, low tongue, or narrow embankment 

of land, which commonly consists of sand or gravel deposited by longshore 

transport. One end of the spit is attached to the mainland, and the other terminates

in open water (usually the sea); a spit is a finger-like extension of the beach. (b) A 

relatively long, narrow shoal or reef extending from the shore into a body of water 

(Jackson 1997).
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 Geoform: Stack (Level 2) – A rocky subaerial landform consisting of a steep 

(and often vertical) column or columns of rock in the sea near a coast which have 

been isolated from the mainland by wave erosion.

 Geoform: Submarine Slide Deposit (Level 1) – This form includes a wide 

variety of mass-movement landforms and processes involving the down slope

transport (under gravitational influence) of soil and rock material en masse. 

Geoforms that could occur within (or as a result of) landslides are Rubble Field.

 Geoform: Swale/Slack (Level 2) – A long, narrow, generally shallow trough-like 

depression between two beach ridges and aligned roughly parallel to the coastline. 

These typically will be found in the intertidal or supratidal zones.

 Geoform: Terrace (Level 1) – Any long, narrow, relatively level or gently 

inclined surface, generally less broad than a plain, but broader than a ledge and

bounded along one edge by a steeper descending slope and along the other by a 

steeper ascending slope. Terraces may border a valley floor or shoreline, and they 

can represent the former position of a flood plain, lake, or sea shore. Terraces may

be created by erosion, wave action, uplift, currents, or any other process.

o Geoform Type: Fluviomarine Terrace (Level 1) – A constructional,

coastal strip, which slopes gently seaward and/or down valley and is

veneered by (or completely composed of) unconsolidated fluviomarine 

deposits—typically silt, sand, and fine gravel (Schoeneberger and 

Wysocki 2005).

o Geoform Type: Wave-Built Terrace (Level 1) – A subaqueous, 

relict, depositional landform originally constructed by river or 

longshore, sediment deposits along the outer edge of a wave-cut 

platform, and then later submerged by rising sea level or subsiding 

land surface (modified from Jackson 1997).

o Geoform Type: Marine Terrace (Level 1) – (a) A narrow, coastal 

strip, formed of deposited material, that slopes gently seaward. (b) An 

elevated marine-cut bench or a wave-cut platform that has been 

exposed by uplift along a seacoast (or by lowering of sea level). 

Marine Terrace may also refer to a wave-cut platform that merges into 

a wave-built terrace (Bates and Jackson 1984).

 Geoform: Tidepool (Level 2) – A pool of salt water left by an ebbing tide that 

generally persists until the next flood tide. These normally occur in rock 

substrates and support diverse animal and plant communities (see Figure 6.4).
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Figure 6.4. Pacific Coast Tidepool, one of the Smallest Features to be Found in the 

Geoform Category.

(courtesy U.S. Fish and Wildlife Service)

 Geoform: Till Surface (Levels 1 & 2) – An area of substrate (predominantly 

unsorted and unstratified drift) that is generally unconsolidated, because it was 

deposited directly by a glacier without subsequent reworking by melt water. The 

surface consists of a heterogeneous mixture of clay, silt, sand, gravel, stones, and 

boulders; rock fragments of various lithologies are imbedded within a finer matrix 

that can range from clay to sandy loam.

 Geoform: Tombolo (Level 1) – A sand or gravel bar or barrier that connects an 

island with the mainland (or with another island).

Geoform Origin: Biogenic

Biogenic geoforms are physical features and landforms that were created by the action of 

living organisms (bioherms). These primarily consist of the different types of reefs. 

Examples of these generally hard, fixed structures include the incorporation of dissolved 

calcium carbonate into reef structure by corals, aggregations of mollusk shells into a 

fixed cohesive substrate, or the cementation of existing sediments into an aggregation of 

worm tubes. As with all geoforms the characteristic of concern in this component is the 

physical shape of these reef features, not the living biology that may have participated in 

their genesis. Any of the reef geoforms may or may not have living coral or other life 

present.

 Geoform: Atoll (Level 1) – A ring-like coral reef that nearly (or entirely)

encloses a reef lagoon. The volcanic island normally associated with an atoll may 
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or may not be present. Atolls appear in plain view as a roughly circular reef that is

surmounted by a chain of closely spaced, low, coral islets that encircle (or nearly 

encircle) a shallow lagoon in which there is no land or islands of non-coral origin; 

the reef is surrounded by open sea.

o Geoform Type: Submerged Atoll/Atoll Reef (Level 1) – Atoll 

structure in which new coral growth has not kept up with rising sea 

levels (or is overcome by the effects of subsidence such that it now lies 

below the surface). It may still support living coral communities.

 Geoform: Burrows/Bioturbation (Level 2) – Tubes, holes, furrows, and small 

mounds formed by the digging, feeding, and movement of benthic fauna. These 

can bring nutrients and other compounds to the surface—as well as destabilize the 

substrate.

o Geoform Type: Tilefish Burrow (Level 2) – Burrows formed by the 

Tilefish (sp.). These can be up to 3 meters wide and 1 - 2 meters deep. 

In some areas, the density of these burrows can be over 1,000 per 

square kilometer, thus significantly altering the benthos.

 Geoform: Coral Reef Island (Levels 1 & 2) – A tropical island built of organic 

material derived from the skeletons of corals and other reef associates. Coral 

islands are usually low and may be several kilometers in size. Typically their 

structure is integrally part of a living or relatively recent coral reef.

 Geoform: Mollusk Reef (Levels 1 & 2) – An area of many shell reefs 

surrounded and intermixed with channels and unvegetated flats.

o Geoform Type: Fringing Mollusk Reef (Level 2 only) – Narrow,

linear reefs, which are usually lying below the marsh platform. These 

reefs form along the shore of tidal creeks, and they are typically 

intertidal (see Figure 6.5).

o Geoform Type: Linear Mollusk Reef (Level 2 only) – Narrow 

straight or sinuous, ridge-like reefs formed primarily by oysters but 

also by other mollusks. These are also usually intertidal. Examples of 

this type of reef can be found in areas with small tidal ranges such as 

Apalachicola Bay and Nueces Bay, Texas (see Figure 6.6).

o Geoform Type: Patch Mollusk Reef (Level 2 only) – Mounded, 

generally round or lobate reefs that have some vertical relief above the 

surrounding substrate. These are usually intertidal, but they can occur 

in subtidal settings (see Figure 6.7).

o Geoform Type: Washed Shell Mound (Level 2 only) – Generally 

linear accumulations of dead shell that form high in the intertidal zone 

along tidal creeks and on the landward side of barrier islands. The 
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shells are loose, and they are usually bleached by the sun—giving 

them a bright appearance (see Figure 6.8).

Figure 6.5. Fringing Mollusk Reef (Made of Oysters) Below a Marsh Platform 

Edge.

Figure 6.6. Linear Mollusk Reef (Made of Oysters) in a Shallow Estuary, Nueces 

Bay, Texas.
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Figure 6.7. Patch Mollusk Reefs (Made of Oysters) in Hamlin Sound, South 

Carolina.

Figure 6.8. Edge of Washed Shell Mound in Espiritu Santo Bay, Texas.
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 Geoform: Deep/Cold-Water Coral Reef (Levels 1 & 2) – Reefs formed by 

deepwater azooxanthellate (i.e., lacking symbiotic algae), stony corals (Order 

Scleractinia). Aggregations of these colonial corals can form structures that range

from small patch reefs that are several meters across, to large reefs and giant 

carbonate mounds up to 300 meters high and several kilometers in diameter; these 

reefs form over many thousands to millions of years (Roberts, Wheeler, and 

Freiwald 2006).

o Geoform Type: Biogenic Deep Coral Reef (Levels 1 & 2) –

Persistent structures, formed by deepwater corals, whose growth 

exceeds (bio) erosion. These reefs result in local topographic highs 

that alter hydrodynamic and sedimentary regimes. The actual reef 

structure remains, often with the growing reefs on their crest or side. 

The coral thickets and skeletal remains trap sediments, contributing to 

the accretion of the reef (Roberts et al. 2009).

o Geoform Type: Deep Coral Carbonate Mound (Levels 1 & 2) –

Topographic seafloor structures that are the result of previous periods 

of coral growth, often with successive periods of reef development, 

sedimentation, and erosion. These are elevated structures, composed of 

coral fossils and accumulated interstitial sediments. This type includes 

structures variously referred to as carbonate knolls, coral banks, biobuildups, and lithoherms. Coral carbonate mounds can take on various 

shapes and sizes, reaching tens of meters in height and tens of 

kilometers in size. They may or may not currently include biogenic 

reefs (Roberts et al. 2009).

 Geoform: Shallow/Mesophotic Coral Reef (Levels 1 & 2) – Light-dependent 

coral reefs that occur within the photic zone (the mesophotic reefs occur in the 

lower part of this zone at depths of 30 - 150 meters).

(http://www.mesophotic.org).

o Geoform Type: Aggregate Coral Reef (Levels 1 & 2) – Continuous, 

high-relief coral formation that occurs in various shapes and lacks sand 

channels. This type includes linear coral formations that are oriented 

parallel to the shelf edge (Zitello et al. 2009).

o Geoform Type: Shallow/Mesophotic Coral Carbonate Mound 

(Levels 1 & 2) – Topographic seafloor structures that are the result of 

previous periods of coral growth, often with successive periods of reef 

development, sedimentation, and erosion. These are elevated 

structures, composed of coral fossils and accumulated interstitial 

sediments. This type includes structures variously referred to as 

carbonate knolls, coral banks, bio-buildups, and lithoherms. Coral 
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carbonate mounds can take on various shapes and sizes, reaching tens

of meters in height and tens of kilometers in size. They may or may 

not currently include biogenic reefs (Roberts et al. 2009).

o Geoform Type: Coral Head/Bomme (Level 2 only) – Individual,

massive coral colonies—usually with a boulder or mound-like shape.

o Geoform Type: Coral Pinnacle (Level 2 only) – A hard, columnar 

structure formed primarily by the growth of hard corals and other 

encrusting organisms. These can occur as isolated vertical structures or 

in association with other pinnacles.

o Geoform Type: Fragile Mesophotic Coral Reef (Levels 1 & 2) –

Coral reef characterized by delicate branching corals and other reef 

organisms.

o Geoform Type: Fringing Coral Reef (Levels 1 & 2) – Fringing 

coral reefs are generally linear and generally aligned with the nearby 

coast. They have the same general morphology as the larger barrier 

reefs but occur at smaller scales.

o Geoform Type: Halo (Levels 1 & 2) – The zone of low-relief, 

generally bare, sand surrounding Patch Coral Reefs. Halos are often 

formed by the action of grazing herbivores in the adjacent patch reef 

itself.

o Geoform Type: Linear Coral Reef (Levels 1 & 2) – These are linear 

coral formations that are oriented parallel to shore or the shelf edge. 

They follow the contours of the shore/shelf edge. This category is used 

for such commonly used terms as forereef, fringing reef, and shelf 

edge reef.

o Geoform Type: Patch Coral Reef (Levels 1 & 2) – Individual patch 

coral reefs are coral formations with circular or oblong shapes and 

vertical reliefs of one meter or more in relation to the surrounding 

seafloor. These reefs are isolated from other coral reef formations by 

bare sand, seagrass, rhodoliths, or other habitats—and have no 

organized structural axis relative to the contours of the insular shelf 

edge (Zitello et al. 2009).

o Geoform Type: Pinnacle Coral Reef (Levels 1 & 2) – A reef 

structure formed by the aggregation of many individual pinnacles

o Geoform Type: Spur and Groove Coral Reef (Levels 1 & 2) –

Habitat having alternating sand and coral formations that are oriented

perpendicular to the shore or bank/shelf escarpment. The coral

formations (spurs) of this feature typically have a high vertical relief

(compared to pavement with sand channels), and they are separated 

from each other by 1 - 5 meters of sand or bare hardbottom 

(grooves)—although the height and width of these elements may vary 
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considerably. This geoform type typically occurs in the forereef or 

bank/shelf escarpment zone.

 Geoform: Tree Fall (Level 2) – Tree falls are trees or woody parts that have 

sunk to the deep ocean floor (generally 2,000 meters or deeper) and may remain 

there for decades. They are colonized by a specialized group of wood-boring 

organisms such as xylophaga (a bivalve) and several crustaceans. Tree falls also 

support a suite of predators and scavengers.

 Geoform: Whale Fall (Level 2) – Whale carcasses that have fallen to the deep 

ocean floor (generally 2,000 meters or deeper), and which support a wide variety 

of arthropods and worms—and a limited number of fish. Whale falls can persist 

for decades (see Figure 6.9).

Figure 6.9. Whale Fall: Skeleton With Hagfish.

 Geoform: Worm Reef (Level 2) – Reefs that consist of the consolidated tubes of 

many individual tube worms, often of the sabellaria and serpulid genera. They 

may be calcareous or siliceous, and the outer surface of these reefs may support 

living worm communities.

o Geoform Type: Patch Worm Reef (Level 2) – These reefs are often 

massive, boulder-like structures separated from each other by 

unconsolidated sediments.

o Geoform Type: Linear Worm Reef (Level 2) – Linear or bench-like 

reefs formed by worms in the intertidal zone.
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Geoform Origin: Anthropogenic

In many coastal and deep oceans, artificial structures (such as piers, breakwaters, 

bulkheads, berms, drilling rigs, and artificial reefs) are a significant part of the 

environment. The continually (or intermittently) submerged portions of features attract 

vagile fauna and provide attachment surfaces for plants and sessile animals. These 

features can also provide shelter from predators and prevailing current, and they can 

support niche communities that increase overall biodiversity. However, these structures 

can also have negative effects (such as altering natural hydrodynamic patterns, interfering 

with animal movement, and increasing contaminant loading into nearshore areas), and 

thus are often of interest to resource managers.

The same relationship between Level 1 and Level 2 geoforms prevails in this origin type 

as in the geologic and biogenic categories; however, due to the complexity of some of the 

anthropogenic structures, many more Level 2 units may be present in a single Level 1 

geoform. Besides physical structures, features that are the result of human activity (such 

as scars and trawl marks) are included among the anthropogenic geoforms.

 Geoform: Aquaculture Structure (Levels 1 & 2) – These structures can take 

many forms: lines suspended over the sediment, floating wooden frameworks

sub-tidal structures attached to the benthos such as wooden piers and platforms, 

and pens and enclosures (both at the surface and submerged). These structures are 

associated with the cultivation of fish, crustaceans, and shellfish for human use or 

consumption. They may be integrated into shallow water bays and ponds, or they 

may be deployed in deeper water. Due to their structural aspects, they can be 

attractive to fish and other animals. They are often sources of nutrients and, thus, 

have impacts on the surrounding ecology.

 Geoform: Artificial Bar (Level 1) – Shoal or bar constructed by human activity 

to influence the movement of water and tides—or reduce surface wave activity 

within an area.

o Geoform Type: Harbor Bar (Level 1) – A bar built across the exit to 

a harbor, in some cases to reduce wave energy within the harbor itself.

 Geoform: Artificial Dike (Level 1) – A raised, linear barrier intended to contain 

or hold back water in order to prevent flooding of adjacent land. These may be 

concrete or fill structures.

o Geoform Type: Artificial Levee (Level 1) – (a) A dike along the side 

of a river channel erected to prevent overflow during floods, usually

running along the channel direction and near the natural levee crests of 

streams. (b) An artificial embankment constructed along the bank of a 

watercourse or an arm of the sea to protect land from inundation (or to 

confine stream flow to its channel).
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 Geoform: Artificial Reef (Level 2) – An artificial structure placed on the ocean 

floor to provide a hard substrate for sea life to colonize. Artificial reefs are 

constructed by sinking dense materials (such as old ships and barges, concreteballasted tire units, concrete and steel demolition debris, and dredge rock) on the 

seafloor within designated reef sites.

 Geoform: Artificial Scar (Level 2) – A gouge or deformation of the bottom, or 

an area where the surface of the substrate, vegetation, or other colonizing 

organisms have been removed by abrasion or impact. These may be temporary or 

permanent features.

o Geoform Type: Prop Scar (Level 2) – A scar that is the result of boat 

or ship propellers making contact with the bottom. Usually these are 

linear features occurring in shallow areas or shoals.

o Geoform Type: Trawling Scar (Level 2) – A groove or cleared area 

of the substrate that is the result of dragging nets or weights across the 

seafloor. These scars can extend for a long distance and may overlap 

older scars. They are generally associated with damage to epibenthic 

organic communities.

 Geoform: Buoy (Level 2) – Anchored objects that float in a relatively fixed 

position at the water surface. Most buoys are used as navigational aids and 

markers for channels, but many buoys also contain scientific or other 

observational instruments.

 Geoform: Breakwater/Jetty (Level 2) – Structures extending more or less 

perpendicularly from the shore into a body of water, which are designed to direct 

and confine the current or tide, to protect a harbor, or to prevent shoaling of a 

navigable inlet by littoral materials.

o Geoform Type: Groin (Level 2) – A small jetty extending 

perpendicular from the shore designed to reduce beach erosion. Groins 

provide hard substrate in what is often an area dominated by 

unconsolidated sediments.

 Geoform: Breachway (Level 2) – The shoreline that is created along the channel 

formed by jetties.

 Geoform: Bulkhead (Level 2) – An artificially reinforced section of the 

shoreline (or the structure itself). These can be composed of piles of natural 

material (such as rip-rap), or they may resemble walls of timbers or other 

substance. They may have many purposes but generally are not intended to 

prevent flooding of lower areas.

 Geoform: Cable Area (Level 1) – An area through which one or more cables 

have been placed in (or on) the substrate. These areas can be navigation hazards, 
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so they are commonly noted on nautical charts. Scarring, debris, and other 

features associated with cable installation or maintenance may be present.

 Geoform: Cable (Level 2) – Structures that serve as linear conduits for electricity 

or as supporting lines for other in-water or above-water infrastructure.

 Geoform: Canal (Levels 1 & 2) – (a) Man-made channels produced to facilitate 

navigation between water bodies. (b) Generally linear, dredged, closed-ended 

ditches that have been dug between housing units along the coast.

 Geoform: Dam (Levels 1 & 2) – An obstruction across a flow that produces a 

lake, pond, or other widening.

 Geoform: Dock/Pier (Level 2) – A landing place for vessels normally oriented 

perpendicular to the shore with a flat surface for off-loading materials. Docks may 

be fixed in position through anchors or piles, or be supported by pilings or other 

structures.

 Geoform: Dredged/Excavated Channel (Levels 1 & 2) – A roughly linear, deep 

area within an existing water body formed by a dredging operation for navigation 

purposes (after Wells et al. 1994).

 Geoform: Dredge Deposit (Levels 1 & 2) – An accumulation on the seafloor (or 

land surface) where spoil materials from a dredging operation are placed. They 

often exhibit some topographical expression and can support biological 

communities that are different than the surrounding area. These deposits are often 

unconsolidated in character, but they can also be relatively stable.

o Geoform Type: Dredge Deposit Shoal (Levels 1 & 2) – A 

subaqueous area that is substantially shallower than the surrounding 

area, which resulted from the deposition of materials from dredging 

and dumping.

o Geoform Type: Dredge Deposit Bank (Levels 1 & 2) – A subaerial 

mound or ridge (which permanently stands above the water) composed 

of randomly mixed sediments deposited during dredging and dumping.

 Geoform: Dredge Disturbance (Level 2) – An area of the seafloor impacted by 

dredging activities. In this instance, the term is meant to apply to secondary 

scarring, smothering, or destruction of epibenthic and near-surface infaunal 

communities by dredging activity (rather than the direct removal of material by 

dredging which would be characterized under the Dredged Channel or other 

geoforms).

 Geoform: Drilling (Oil and Gas) Rig (Level 2) – Large structures built to house 

workers and machinery needed to drill wells in the ocean bed in order to extract 

oil or other natural resources. They may be attached to the ocean floor, consist of 
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an artificial island, or be floating; rigs often provide important structure and 

attachment points for marine animals.

 Geoform: Fill Area (Level 2) – A topographically low area into which 

unconsolidated material has been placed in order to raise the ground level as part 

of development or expansion of coastal infrastructure.

o Geoform Type: Landfill (Level 2) – A fill area where some form of 

solid waste is being used as the fill material.

 Geoform: Fish Pond (Level 2) – These are mostly enclosed basins, usually along 

the shore used to trap fish. During high tide they are open to the sea but as the tide 

recedes they become cut off to allow capture of the trapped fish. These features 

may be very old and have strong cultural and archaeological significance.

 Geoform: Harbor (Level 1) – A small bay or a sheltered part of a sea, lake, or 

other large body of water. A harbor is usually well protected (either naturally or 

artificially) against high waves and strong currents and serves as a safe anchorage 

for ships and where port facilities are present. Many smaller anthropogenic 

geoforms may be encountered within a harbor.

 Geoform: Lock (Level 2) – A chamber designed to lift vessels—from one water 

body to another—by adjusting the level of water in the chamber.

 Geoform: Lost/Discarded Fishing Gear (Level 2) – This consists of nets, floats, 

weights and cabling associated with fishing activities, usually at a commercial 

level. This type of debris forms a serious hazard for marine life and can persist in 

the environment for long periods.

 Geoform: Marina/Boat Ramp (Level 2) – A series of docks, walkways, slips, 

and support infrastructure (such as cables and small pipelines) for in-water 

storage of yachts and boats. Marinas commonly include one or more boat ramps, 

which consist of a sloping driveway for launching small, trailered vessels.

 Geoform: Mooring Field (Level 1) – These are anchorages with many small,

fixed buoys in place for securing yachts and other vessels.

 Geoform: Mosquito Ditch (Level 2) – Straight, narrow channels that were dug 

to drain the upper reaches of salt marshes in order to control the populations of 

mosquitoes that breed there. However, draining the standing water also impacts

populations of mosquito-eating fish that live in those waters 

(http://www.edc.uri.edu/restoration/html/intro/salt.htm).

 Geoform: Outfall/Intake (Level 2) – Outfalls are pipelines or tunnels that 

discharge municipal or industrial wastewater, storm water, combined sewer 

overflows, cooling water, or brine effluents to a receiving water body. Intakes are 
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pipes designed (and placed) to draw lake or seawater into a man-made pond or 

other facility.

Figure 6.10. Pilings Supporting an Abandoned Trestle in Humboldt Bay, 

California.

 Geoform: Pilings (Level 2) – A structure formed by piles that are long, slender 

columns—usually made of timber, steel, or reinforced concrete (see Figure 6.10).

 Geoform: Pipeline Area (Level 1) – A corridor through which one or more 

pipelines have been placed.

 Geoform: Rip Rap Deposit (Level 2) – An accumulation of rock or boulders 

placed along a waterway or shoreline to reduce erosion.

 Geoform: Salt Pond Complex (Level 1) – A series of shallow ponds separated 

by berms or levels, designed to produce salt from marine water or other brines 

through the process of evapotranspiration. The ponds are periodically drained to 

harvest salts. These can support various microalgal communities while water is 

present.

 Geoform: Salt Pond (Level 2) – Usually enclosed areas just landward of the 

shoreline with a permanent-to-intermittent flooding regime of saline-tohypersaline waters.

 Geoform: Seawall (Level 1) – A man-made wall or embankment of stone, 

reinforced concrete, or other material along a shore that was built to prevent wave 
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erosion. These are similar to jetties, but seawalls are more commonly oriented 

along the water’s edge (instead of perpendicular to the shore).

 Geoform: Tidal/Wave Energy Structure (Level 2) – Structures that consist of 

long booms deployed at the surface or turbines placed on the seafloor or other 

structures. Some portions of these structures may form attachment surfaces for 

sessile fauna.

 Geoform: Trash Aggregation (Levels 1 and l 2) – Aggregations of submerged, 

floating or suspended trash. These may be loose and mobile as when floating at 

the water’s surface or consolidated by sediment on the bottom or along shore. 

Trash aggregations may be the result of local storm or seismic events such as 

floods or tsunamis. Trash aggregations can also form over long periods due to the 

action of large gyres and currents as in the mid-Pacific Ocean.

 Geoform: Wharf (Level 2) – A structure on the shore of a harbor where ships 

may dock to load and unload cargo or passengers. A wharf is usually a fixed 

platform, often on pilings. Smaller and more modern wharves are sometimes built 

on flotation devices (pontoons) to keep them at the same level as the ship—even 

during changing tides. Wharves form attachment surfaces for shellfish and sessile 

epifauna, and they are common aggregation points for fish. Also, wharves are 

often locations where contaminants are introduced into the environment (through 

spills or waste disposal).

 Geoform: Wind Energy Structure (Level 2) – Structures deployed in the 

marine environment in order to produce energy from the wind. These structures

often consist of piling, cabling supports, and associated anchoring devices.

 Geoform: Wreck (Level 2) – Any of a variety of man-made structures (such as 

sunken ships or collapsed drilling rigs) that have fallen to the seafloor. They may 

be either completely or partially submerged. Wrecks often provide valuable 

habitat for attaching organisms or fish, but they may also leach contaminants into 

the environment.

6.5 Status of Geoform Component Units

Compiling a comprehensive list of geoforms can be a challenge—given the broad 

geography addressed by the CMECS, the range of scales across which these features can 

occur, and the subtle differences between them. The geoforms presented in Section 6

should be considered an initial—not final—list, which focuses on those features that 

exert an influence on biological communities and generally surround (or encompass)

biological units in the Biotic Component.

In addition, it is recognized that there are many colloquial terms for geoform units. 

These terms often reflect local conditions and can have historical meaning. CMECS 

geoform units are not intended to include all the local variations in terminology but rather 
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to focus on unit names that reflect the shape, morphology, and aspect of landform 

features. Users are encouraged to use the CMECS units as the primary attribute for a 

feature but are not prohibited from providing additional attribution using a colloquial 

term when this will enhance usability of the data. Generally the process which resulted in 

a geoform is not included in the geoform type name, although some exceptions to this 

approach have been made when the process results in a unique variant of the geoform 

(e.g., ebb tidal delta).

6.6 Geoform Component Modifiers

The following is a list of modifiers relevant to the GC. Users are free to apply these as 

appropriate for project goals and as data supports their use. Users are not obligated nor 

limited to the list below.

 Anthropogenic

o Anthropogenic Impact

 Biogeographic

o Primary Water Source

 Physical

o Energy Intensity

o Energy Type

o Induration

o Seafloor Rugosity

o Small-scale Slope

o Surface Pattern

o Tidal Regime (Amplitude)

 Spatial

o Benthic Depth Zones

o Coral Reef Zone

o Enclosure

o Profile

 Temporal

o Temporal Persistence
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7. Substrate Component

Substrate is defined in CMECS as the non-living materials that form an aquatic bottom or 

seafloor, or that provide a surface (e.g., floating objects, buoys) for growth of attached 

biota. Substrate may be composed of any substance, natural or manmade. Describing the 

composition of the substrate is a fundamental part of any ecological classification 

scheme. Substrate provides context and setting for many aquatic processes, and it 

provides living space for benthic and attached biota. The Substrate Component (SC) is a 

characterization of the composition and particle size of the surface layers of the substrate; 

this component is designed to be compatible with a range of sampling tools. The SC

provides guidance to characterize the layers of substrate that support the majority of 

multicellular life – the upper layer of hard substrate, or (typically) the upper 15 

centimeters of soft substrate – in a way that is consistent with a variety of past practices. 

The SC and the BC describe the non-living (SC) and living (BC) aspects of a plan-view 

perspective of the seafloor at comparable scales. SC observational unit scales range from 

sediment corers or grabs, to sediment profile or plan-view photographs of the seafloor, to 

defined quadrats or transects, to video clips, to high-resolution acoustic images. At larger 

scales, the structure, shape, and surface pattern of substrate features are described by the 

Geoform Component (GC).

7.1 Commonly Used Methods for Classifying Substrate Geology

Several approaches are now commonly used for describing substrate geology. In these 

approaches, the classification of sediment particle size is a basic element, which dictates 

the overall structure of the classification in many ways. Two approved FGDC standards, 

the Classification of Wetlands and Deepwater Habitats in the United States and the 

National Vegetation Classification Standard (FGDC-STD-004 and FGDC-STD-006, 

respectively) provide differing sets of definitions for classifying sediment grain size. A

third set of definitions—based on Wentworth (1922)—is also in widespread use in the 

marine geological community and internationally (Shepard 1954; Folk 1974; Flemming 

2000). An important goal of CMECS is to promote a single, consistent, and unified 

approach for classification—while at the same time maximizing compatibility with past 

practice and data. 

Different grain size definitions present a significant complication in the unification of 

common substrate classification systems. For example, sand is defined differently under 

each system. All classifications specify 2 millimeters as the upper-end limit of sand 

particles, but the lower-end limit varies: FGDC-STD-004 specifies 0.074 millimeters,

FGDC-STD-006 specifies 0.05 millimeters, and many of the other published methods 

that are based on Wentworth (1922) specify 0.0625 millimeters. For most sediment 

samples, these differences in sand definitions are not substantial; the “percent sand” 

calculated under each system will be quite comparable for the great majority of samples. 
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However, these definition differences are more problematic with regard to consistent 

classification, data analysis, quality control, and quality assurance.

Because there is no clear FGDC-approved option for classifying marine sediment grain 

size, CMECS adopts the Wentworth (1922) standard for mineral grain size definitions 

(Table 7.1). This scale reflects long-standing marine traditions and is used by a majority 

of marine scientists. The Wentworth standard is based on phi class sizes (-log 2 of particle 

diameter in millimeters), and provides the foundation for particle size classifications in 

many published works and methods (Shepard 1954, Folk 1954, Flemming 2000, 

Valentine et al. 2005). Virtually all legacy datasets and recent measurements in marine 

waters use the Wentworth scale, including datasets from the Coastal and Marine Geology 

Program of the USGS. 

Table 7.1. Mineral Grain Size Descriptors for CMECS (modified from Wentworth 

1922). CMECS uses the term Mud to describe all particles smaller than sand (less than 

0.0625 millimeters). The term Gravel is used to describe all rock fragment particles that 

are 2 millimeters or larger.

Descriptor Grain Size (millimeters) Class Sizes (phi)

Clay < 0.004 > 8

Silt 0.004 to < 0.0625 > 4 to 8

Mud < 0.0625 > 4

Sand 0.0625 to < 2 4 to < -1

 (Very Fine Sand) 0.0625 to < 0.125 4 to < 3

 (Fine Sand) 0.125 to < 0.25 3 to < 2

 (Medium Sand) 0.25 to < 0.5 2 to < 1

 (Coarse Sand) 0.5 to < 1 1 to < 0

 (Very Coarse Sand) 1 to < 2 0 to < -1

Gravel 2 to < 4,096 -1 to < -12

Granule 2 to < 4 -1 to < -2

Pebble 4 to < 64 -1 to < -6

Cobble 64 to < 256 -6 to < -8

Boulder 256 to < 4,096 -8 to < -12
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Figure 7.1 presents a grain-size translator to allow comparisons among the different 

systems in common use. As CMECS classifications are applied more widely, it is hoped 

that improved methods for translating data among approaches will continue to be 

developed (e.g., Poppe et al. 2003). This may enable graceful transitions between 

CMECS data and data processed using other systems.

Figure 7.1. Sediment Grain Size Translator Diagram.

This diagram allows comparisons among three different grain size classification systems 

in common use (FGDC-STD-004, FGDC-STD-006, and Wentworth). Figure modified 

from Schoeneberger et al. (2002).

After a sample is assessed for the distribution of particle sizes, practitioners need a 

convenient and descriptive way to characterize the mixture and classify the sample. There 

are several classifications available for mineral sediment mixes, including Folk (1954), 

Shepard (1954), and Schlee (1973), which is a modification of Shepard. These are all 

based on the sedimentological approach of describing depositional environments with 

ternary diagrams. 

In order to be consistent with commonly accepted marine classifications, the SC uses the 

Folk (1954) approach to classifying mineral sediment mixes. CMECS utilizes the original 

Folk ternary diagrams and Folk threshold values for Gravel-Sand-Mud combinations and 

for Sand-Silt-Clay combinations. This classification also provides good descriptive power 

since, by design, it incorporates all Wentworth grain size bins. The two Folk ternary 

diagrams are provided in Figure 7.2, which adds colors to show the hierarchical 

framework of the CMECS SC applied to the Folk diagrams. A few words are changed 

from the original work, to avoid duplication of terms in a single hierarchy (e.g. Muddy 

Sand becomes Silty-Clayey Sand in the Sand-Silt-Clay diagram).
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Figure 7.2. Ternary Diagrams for Gravel-Sand-Mud and Sand-Silt-Clay.

and for Sand-Silt-Clay, adapted from Folk (1954). Image: K. Ford.
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CMECS adopted Folk (1954) due to the clear present-day preferences for it among public 

and invited reviewers of CMECS, its long-standing historical use in marine work, and its 

straight-forward approach to classification. In addition to Folk (1954), however, two 

existing FGDC classifications for substrate mixtures were considered for applications in 

CMECS. Of these, the Classification of Wetlands and Deepwater Habitats in the United 

States, FGDC-STD-004 (FGDC 1996b) addresses mostly aquatic substrate as sediment, 

and provides a fairly coarse method of classification into six major geology-based units. 

In contrast, the Soil Geographic Data Standard, FGDC-STD-006 (FGDC 1997) and 

Keys to Soil Taxonomy (Soil Survey Staff 2010) together provide more detailed 

classification options for classifying soils with many hundreds of descriptors that have 

been used in soil science for decades. A soils approach specifically recognizes and 

describes the biological, physical, and chemical processes that form (and alter) the 

substrate as part of classification. Through the National Cooperative Soil Survey, soil 

maps are available for all intertidal and supratidal areas of the United States. Users 

should consider these sources and approaches when classifying substrate in these areas.

Although soils approaches have in the past been used mostly for terrestrial work, some 

coastal scientists (and the USDA Natural Resources Conservation Service) are now 

applying soil taxonomies to shallow subtidal environments with good results (see Demas, 

Rabenhorst, and Stevenson 1996; Bradley and Stolt 2006; Stolt et al. 2011). Practitioners 

interested in soils approaches to classifying shallow subtidal (Estuarine Coastal 

Subsystem) substrate should consult Keys to Soil Taxonomy (Soil Survey Staff 2010), and 

Schoeneberger et al. (2002). It is recommended that a soils approach be used if a more 

detailed classification is needed for interpretations and management of shallow-water

substrate.

7.2 Application of the Substrate Component

The SC attempts to characterize and classify the most ecologically significant geological 

features of the substrate surface according to composition and particle size. Shape, 

pattern, and structural features of the seabed are covered in the GC; living elements are 

covered in the BC.

To illustrate relationships among SC and BC classifications, SC units represent the nonliving components that support, intersperse, or overlay the living components described 

in the BC—for example, SC’s Fine Unconsolidated Substrate–Mud unit may support 

biological communities such as the BC’s Faunal Bed unit describing Ophiuroids or brittle 

stars. Similarly, the physical structure and setting of an SC Coral Reef Substrate may be 

found underneath a living BC Coral Reef Biota Subclass. Here, the BC would further 

describe the living layer of corals or—if no live corals are present—whatever other 

organisms are colonizing the reef (e.g., macroalgae). This same logic applies to mollusk 

reefs; the SC describes only the physical substrate created by mollusks (e.g., an oyster 
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reef), while the BC describes the biota currently living on that substrate. This biota may 

be live oysters—or it may be attached macroalgae or other colonizers, if the oysters have 

perished. When substrate builders are the dominant living component, classification 

terms may seem to be repeated in both SC and BC classes and subclasses. For instance, 

the Mussel Reef Substrate Group describes the structural and non-living substrate created 

by mollusks, while the BC Class Reef Biota and Subclass Mollusk Reef describe the 

living mollusks (if they are the dominant life form colonizing that substrate at the time of 

sampling or observation).

To enable maximum flexibility of methods, the percent cut-offs that define SC 

classifications (bins) may be used and reported in % weight (for retrieved samples), in % 

cover (for plan-view seafloor images), or in % composition (for large-scale approaches, 

sediment profile images, and other approaches), as directed for each classification type. 

While the SC and other CMECS components are intended to be scale-independent and 

method-independent, the reported scale of substrate “patchiness” is determined by the 

scale of observation, and so is somewhat method-dependent. To assist with 

comparability, practitioners should always report sampling gear, methods, units, scale of 

observation, and scale of reporting in project metadata. Data users should be aware of the 

methods that were used to collect and report data, and should make note of any data 

limitations that may exist.

Mixtures of all different substrate types are very common in nature, and the CMECS SC 

provides methods and descriptors for classifying various mixes of substrate. More 

detailed and descriptive Modifiers (to describe mixes, layers, and more) can also be 

incorporated into SC classifications. This is presented in Section 10 and Section 12.

7.3 Hierarchical Structure

The SC hierarchy is designed to be compatible with a wide variety of possible sampling 

tools. So, for instance, rapid tools (e.g., cameras and certain acoustic devices) may be 

used to identify the higher classification levels, while finer and more time-consuming 

tools (e.g., sediment retrieval and analysis) will be capable of resolving finer levels of the 

classification. The hierarchical structure of this component includes five levels: Substrate 

Origin, Substrate Class, Substrate Subclass, Substrate Group, and Substrate Subgroup. 

However, the last two levels are not used in every Substrate Origin.

Table 7.2. Substrate Component Classification Structure.

Substrate Component

Substrate Origin

 Substrate Class

 Substrate Subclass

 Substrate Group

 Substrate Subgroup
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7.3.1 Substrate Origin

The first level of classification in the SC is substrate origin, which is subdivided into 

Geologic Substrate, Biogenic Substrate, and Anthropogenic Substrate. The substrate 

origin type is assigned based on dominance (greatest percent cover) of either the 

geologic, biogenic (but no longer living), or anthropogenic upper layer of substrate. 

Mixes of origins are addressed through Co-occurring Elements Modifiers (see Section 

10).

7.3.2 Substrate Classes and Subclasses

Substrate classes and substrate subclasses are determined by the composition and particle

size of the dominant substrate origin in the surface sediments. Class and subclass

definitions represent a merging of approaches from Wentworth (1922), Folk (1954), and 

the FGDC-STD-004.

7.3.3 Substrate Groups and Subgroups

Substrate groups and substrate subgroups are determined by Folk (1954) mixes for 

Geologic Sediments and by taxa for the Biogenic Substrates. Groups and subgroups are 

not used for Anthropogenic Substrates.

7.4 Substrate Component Units

7.4.1 Substrate Origin: Geologic Substrate

Benthic substrates where percent cover of Rock and Unconsolidated Mineral Substrate

exceeds percent cover of both Biogenic and Anthropogenic Substrates, considered 

separately. When Geologic Substrate is present, but does not constitute the dominant 

substrate origin, it may be included as a Co-occurring Element.

Substrate Class: Rock Substrate

Igneous, metamorphic, or sedimentary rock with particle sizes greater than or equal to 4.0 

meters (4,096 millimeters) in any dimension that cover 50% or greater of the Geologic

Substrate surface.

 Substrate Subclass: Bedrock – Substrate with mostly continuous formations of 

bedrock that cover 50% or more of the Geologic Substrate surface.

 Substrate Subclass: Megaclast – Substrate where individual rocks—with 

particle sizes greater than or equal to 4.0 meters (4,096 millimeters) in any 

dimension—cover 50% or more of the Geologic Substrate surface.
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Substrate Class: Unconsolidated Mineral Substrate

Geologic Substrates with less than 50% cover of Rock Substrate. This class uses Folk 

(1954) terminology to describe any mix of loose mineral substrate that occurs at any 

range of sizes—from Boulders to Clay. This hierarchy and the associated terms are 

shown in Figure 7.2. These classifications may be based on percent weight (e.g., for 

retrieved samples); percent cover (e.g., for plan-view images); or visual percent 

composition (for other approaches). Units with bracketed letters, e.g., [G], [mSG], 

correspond to the labeled polygons in Figure 7.2, using conventions from Folk (1954).

 Substrate Subclass: Coarse Unconsolidated Substrate – Geologic Substrate 

surface layer contains > 5% Gravel (particles 2 millimeters to < 4,096 

millimeters). These sediments are classified using the upper three rows of the 

Folk (1954) Gravel-Sand-Mud diagram.

o Substrate Group: Gravel [G] - Geologic Substrate surface layer contains 

> 80% Gravel (particles 2 millimeters to < 4,096 millimeters diameter).

 Substrate Subgroup: Boulder – Geologic Substrate contains >

80% Gravel, with a median Gravel size of 256 millimeters to 

< 4,096 millimeters.

 Substrate Subgroup: Cobble – Geologic Substrate contains >

80% Gravel, with a median Gravel size of 64 millimeters to

< 256 millimeters.

 Substrate Subgroup: Pebble – Geologic Substrate contains >

80% Gravel, with a median Gravel size of 4 millimeters to 

< 64 millimeters.

 Substrate Subgroup: Granule – Geologic Substrate contains >

80% Gravel, with a median Gravel size of 2 millimeters to 

< 4 millimeters.

o Substrate Group: Gravel Mixes – Geologic Substrate surface layer 

contains 30% to < 80% Gravel (particles 2 millimeters to < 4,096 

millimeters in diameter). For more specificity in this group and in the 

following three substrate subgroups, the median size of “Gravel” may be 

substituted in, e.g., “Pebble Mixes”, “Sandy Boulder”, “Muddy Sandy 

Cobble”, and “Muddy Granule”.

 Substrate Subgroup: Sandy Gravel [sG] – Geologic Substrate is 

30% to < 80% Gravel, with Sand composing 90% or more of the 

remaining Sand-Mud mix.

 Substrate Subgroup: Muddy Sandy Gravel [msG] – Geologic 

Substrate is 30% to < 80% Gravel, with Sand composing from 

50% to < 90% of the remaining Sand-Mud mix.
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 Substrate Subgroup: Muddy Gravel [mG] – Geologic Substrate 

is 30% to < 80% Gravel, with Mud composing 50% or more of the 

remaining Mud-Sand mix.

o Substrate Group: Gravelly – Geologic Substrate surface layer contains 

5% to < 30% Gravel (particles 2 millimeters to < 4,096 millimeters in 

diameter). For more specificity in this group and in the following three 

substrate subgroups, the median size of “Gravelly” may be substituted in, 

e.g., “Bouldery”, “Cobbley Sand”, “Pebbly Muddy Sand”, and “Granuley 

Mud”.

 Substrate Subgroup: Gravelly Sand [gS] – Geologic Substrate is 

5% to < 30% Gravel, and the remaining Sand-Mud mix is 90% or 

more Sand.

 Substrate Subgroup: Gravelly Muddy Sand [gmS] – Geologic 

Substrate is 5% to < 30% Gravel, and the remaining Sand-Mud 

mix is 50% to < 90% Sand.

 Substrate Subgroup: Gravelly Mud [gM] – Geologic Substrate 

is 5% to < 30% Gravel, and the remaining Sand-Mud mix is 50% 

or more Mud.

 Substrate Subclass: Fine Unconsolidated Substrate – Geologic Substrate 

surface layer contains less than 5% gravel (particles 2 millimeters to < 4,096 

millimeters in diameter). These sediments are classified using the bottom two 

rows of the Folk (1954) Gravel-Sand-Mud diagram, and the entire Folk (1954) 

Sand-Silt-Clay diagram.

o Substrate Group: Slightly Gravelly – Geologic Substrate surface layer 

contains from a trace (0.01%) of Gravel to 5% Gravel (particles 2 

millimeters to < 4,096 millimeters in diameter). For more specificity in 

this group and in the following four substrate subgroups, the median size 

of “Gravelly” may be substituted in, e.g., “Slightly Granuley”, “Slightly 

Pebbly Sand”, “Slightly Cobbley Muddy Sand”, and “Slightly Bouldery 

Mud”.

 Substrate Subgroup: Slightly Gravelly Sand [(g)S] – Geologic 

Substrate is 0.01% to < 5% Gravel, and the remaining Sand-Mud 

mix is 90% or more Sand.

 Substrate Subgroup: Slightly Gravelly Muddy Sand [(g)mS] –

Geologic Substrate is 0.01% to < 5% Gravel, and the remaining 

Sand-Mud mix is 50% to < 90% Sand.
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 Substrate Subgroup: Slightly Gravelly Sandy Mud [(g)sM] –

Geologic Substrate is 0.01% to < 5% Gravel, and the remaining 

Sand-Mud mix is 50% to < 90% Mud.

 Substrate Subgroup: Slightly Gravelly Mud [(g)M] – Geologic 

Substrate is 0.01% to < 5% Gravel, and the remaining Sand-Mud 

mix is 90% or more Mud.

o Substrate Group: Sand [S] – Geologic Substrate surface layer contains 

no trace of Gravel and is composed of > 90% Sand (particles 0.0625

millimeters to < 2 millimeters in diameter).

 Substrate Subgroup: Very Coarse Sand – Geologic Substrate 

surface layer contains no trace of Gravel and is composed of >

90% Sand, with a median grain size of 1 millimeter to < 2 

millimeters.

 Substrate Subgroup: Coarse Sand – Geologic Substrate surface 

layer contains no trace of Gravel and is composed of > 90% Sand,

with a median grain size of 0.5 millimeters to < 1 millimeter.

 Substrate Subgroup: Medium Sand – Geologic Substrate surface 

layer contains no trace of Gravel and is composed of > 90% Sand,

with a median grain size of 0.25 millimeters to < 0.5 millimeters.

 Substrate Subgroup: Fine Sand – Geologic Substrate surface 

layer contains no trace of Gravel and is composed of > 90% Sand

with a median grain size of 0.125 millimeters to < 0.25 

millimeters.

 Substrate Subgroup: Very Fine Sand – Geologic Substrate 

surface layer contains no trace of Gravel and is composed of >

90% Sand with a median grain size of 0.0625 millimeters to < 

0.125 millimeters.

o Substrate Group: Muddy Sand – Geologic Substrate surface layer 

contains no trace of Gravel and is composed of 50% to < 90% Sand 

(particles 0.0625 millimeters to 2 millimeters in diameter); the remainder 

is composed of Mud (particles less than 0.0625 millimeters in diameter).

 Substrate Subgroup: Silty Sand [zS] – Geologic Substrate 

surface layer shows no trace of Gravel and contains 50% to < 90% 

Sand; the remaining Silt-Clay mix is 67% or more Silt.

 Substrate Subgroup: Silty-Clayey Sand [zcS] – Geologic 

Substrate surface layer shows no trace of Gravel and contains 50% 

to < 90% Sand; the remaining Silt-Clay mix is 33% to < 67% Silt.
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 Substrate Subgroup: Clayey Sand [cS] – Geologic Substrate 

surface layer shows no trace of Gravel and contains 50% to < 90% 

Sand; the remaining Clay-Silt mix is 67% or more Clay.

o Substrate Group: Sandy Mud [sM] – Geologic Substrate surface layer 

contains no trace of Gravel and is composed of 10% to < 50% Sand; the 

remainder is composed of Mud (particles less than 0.0625 millimeters in 

diameter).

 Substrate Subgroup: Sandy Silt [sZ] – Geologic Substrate 

surface layer shows no trace of Gravel and contains 10% to < 50% 

Sand; the remaining Silt-Clay mix is 67% or more Silt.

 Substrate Subgroup: Sandy Silt-Clay [sZC] – Geologic 

Substrate surface layer shows no trace of Gravel and contains 10% 

to < 50% Sand; the remaining Silt-Clay mix is 33% to < 67% Silt.

 Substrate Subgroup: Sandy Clay [sC] – Geologic Substrate 

surface layer shows no trace of Gravel and contains 10% to < 50% 

Sand; the remaining Clay-Silt mix is 67% or more Clay.

o Substrate Group: Mud [M] – Geologic Substrate surface layer contains

no trace of Gravel and is composed of 90% or more Mud (particles less 

than 0.0625 millimeters in diameter); the remainder (< 10%) is composed

of Sand (particles 0.0625 millimeters to < 2 millimeters in diameter).

 Substrate Subgroup: Silt [Z] – Geologic Substrate surface layer 

shows no trace of Gravel and contains < 10% Sand; the remaining 

Silt-Clay mix is 67% or more Silt.

 Substrate Subgroup: Silt-Clay [ZC] – Geologic Substrate 

surface layer shows no trace of Gravel and contains < 10% Sand; 

the remaining Silt-Clay mix is < 33% to 67% Silt.

 Substrate Subgroup: Clay [C] – Geologic Substrate surface layer 

shows no trace of Gravel and contains < 10% Sand; the remaining 

Clay-Silt mix is 67% or more Clay.

7.4.2 Substrate Origin: Biogenic Substrate

Substrates where percent cover of non-living Biogenic Substrate exceeds percent cover of 

both Geologic Substrate and Anthropogenic Substrates, when all are considered 

separately. Biogenic substrates are classified at the higher levels by taxonomy, and at the 

lower levels by median particle size—using the units Reef Substrate (> 4,096 

millimeters), Rubble (64 millimeters to < 4,096 millimeters), Hash (2 millimeters to < 64 

millimeters), and Sand (0.0625 millimeters to < 2 millimeters). These units are derived 
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from Wentworth (1922), and they can be broken down into Wentworth grain size classes 

for greater precision, if desired. Biogenic Substrate classifications may be based on 

percent weight (e.g., for retrieved samples); percent cover (e.g., for plan-view images); 

and visual percent composition (for other approaches). The terms “dominant” and 

“primarily” in the Biogenic Substrate Origin describe the substrate type that is present in 

the greatest percent cover, greatest percent weight, or greatest visual percent composition. 

When two Biogenic Substrate types are present, “dominant” and “primarily” are 

equivalent to “> 50%”. When three or more types exist, the dominant type may occur at a 

lower percent-of-total value. Biogenic Substrate types that are present, but do not 

constitute the dominant feature, may be included as a Co-occurring Element modifier 

(see Section 10).

Substrate Class: Algal Substrate 

Biogenic Substrate that is primarily composed of calcareous algae in various states of 

decomposition, including both crustose and coralline types.

 Substrate Subclass: Algal Sand – Biogenic Substrate that is primarily composed 

of broken down calcareous algae with a median particle size of 0.0625

millimeters to < 2 millimeters (Sand). This Sand may have a characteristic white 

color as it becomes bleached by the sun. However, when the composition and 

origin of Sand is unclear, it is assumed to be mineral Sand, and is classified as a 

Geologic Origin substrate.

o Substrate Group: Halimeda Sand – Biogenic Substrate that is primarily 

composed of recognizable, broken segment-like fronds of Halimeda, a 

green coralline alga, and has a median particle size of 0.0625 millimeters

to < 2 millimeters (Sand).

 Substrate Subclass: Rhodolith Substrate – Biogenic Substrate that is primarily 

composed of crustose algae that form rounded calcareous nodules (rhodoliths), 

often associated with coral reefs.

o Substrate Group: Rhodolith Rubble – Substrate that is dominated by 

living or non-living Rhodolith Rubble, with a median particle size of 64 

millimeters to < 4,096 millimeters (Cobbles and Boulders).

o Substrate Group: Rhodolith Hash – Substrate that is dominated by 

living or non-living Rhodolith Hash, with a median particle size of 2 

millimeters to < 64 millimeters (Granules and Pebbles).

o Substrate Group: Rhodolith Sand – Substrate that is dominated by 

Rhodolith Sand, with a median particle size of 0.0625 millimeters to < 2 

millimeters (Sand). When the composition and origin of Sand is unclear, 

it is assumed to be mineral Sand, and is classified as a Geologic Origin 

substrate.
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Substrate Class: Coral Substrate

Non-living scleractinian coral reefs (or coral particles) constitute the dominant benthic 

substrate; this substrate may or may not be inhabited by live corals.

 Substrate Subclass: Coral Reef Substrate – Substrate that is dominated by 

living or non-living coral reefs with a median particle size of 4,096 millimeters or 

greater in any dimension.

 Substrate Subclass: Coral Rubble – Substrate that is dominated by living or 

non-living coral Rubble with a median particle size of 64 millimeters to < 4,096 

millimeters (Cobbles and Boulders).

 Substrate Subclass: Coral Hash – Substrate that is dominated by coral Hash 

with a median particle size of 2 millimeters to < 64 millimeters (Granules and 

Pebbles).

 Substrate Subclass: Coral Sand – Substrate that is dominated by coral Sand 

with a median particle size of 0.0625 millimeters to < 2 millimeters (Sand). When 

the composition and origin of Sand is unclear, it is assumed to be mineral Sand, 

and is classified as a Geologic Origin substrate.

Substrate Class: Organic Substrate

Surface layers of substrate are primarily composed of non-living organic material,

including fine or coarse organic particles up to 4,096 millimeters in any dimension. 

Substrates dominated by roots of live vegetation may be classified after removing the 

root material, and/or they may be classified by specialized methods considering, for 

example, below-ground biomass. Live fauna, and live flora together with their living root 

masses, are covered in the BC.

 Substrate Subclass: Organic Debris – Organic substrate is primarily composed 

of coarse organic material that is relatively intact, with a median particle size from 

4 millimeters to < 4,096 millimeters (the size of Pebbles, Cobbles, and Boulders). 

Organic Debris that is larger than that (e.g., whale falls, tree falls) is covered in 

the Geoform Component.

o Substrate Group: Peat Debris – Organic substrates that are primarily 

composed of non-living peat deposits—from modern or prehistoric times.

o Substrate Group: Woody Debris – Organic substrates that are primarily 

composed of small trees, branches, wood, or wood fragments that are 

broken into particles with a median particle size from 4 millimeters to 

4,096 millimeters.

 Substrate Subgroup: Fine Woody Debris – Woody Debris with 

a median particle size from 4 millimeters to < 64 millimeters.
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 Substrate Subgroup: Coarse Woody Debris – Woody Debris 

with a median particle size from 64 millimeters to < 256 

millimeters.

 Substrate Subgroup: Very Coarse Woody Debris – Woody 

Debris with a median particle size from 256 millimeters to < 4,096

millimeters.

 Substrate Subclass: Organic Detritus – Unconsolidated organic substrate that is 

composed primarily of decomposing plant and animal tissues. Organic Detritus is 

mostly broken down—with a median particle size from 0.0625 millimeters to 4 

millimeters (Sand and Granule)—and is often in an advanced state of utilization 

and decay. Organic Detritus may be produced in-situ, deposited from above, or 

transported horizontally, or may be remnant material.

 Substrate Subclass: Organic Mud – Unconsolidated organic substrate with a 

median particle size of less than 0.0625 millimeters (Silts, Clays, and Muds), and 

an organic carbon content of greater than 5%.

Substrate Class: Ooze Substrate

Deep sea substrates that are composed of > 30% tests, shells, or frustules of small 

plankton, including diatoms, radiolarians, pteropods, foraminifera, and other marine 

plankters. Oozes are common in deeper waters far from shore, where terrestrial inputs to 

the bottom sediments are very low, and where surface productivity is reasonably high. 

Based on common practice in the field, definition of a substrate as “ooze” requires a 30% 

or greater (but not necessarily “dominant”) ooze composition within the sediments. Once 

defined as an “ooze”, type of ooze is determined by dominant percent composition.

 Substrate Subclass: Carbonate Ooze – Oozes that are formed primarily from 

the calcium carbonate-based shells of foraminifera, coccolithophores, pteropods, 

or other calcareous plankton. These oozes are limited to seafloors shallower than 

the carbonate compensation depth (4 - 5 kilometers); calcium carbonate dissolves 

in the cold acidic waters deeper than this.

o Substrate Group: Coccolithophore Ooze – Oozes that are formed 

primarily from carbonate tests of phytoplanktonic coccolithophores.

o Substrate Group: Foraminiferan Ooze – Oozes that are formed 

primarily from carbonate tests of foraminiferans.

 Substrate Subgroup: Globigerina Ooze – Oozes that are 

formed primarily from multi-chambered carbonate tests of the 

foraminiferan Genus Globigerina.

o Substrate Group: Pteropod Ooze – Oozes that are formed primarily 

from the shells of pteropods (a group of planktonic mollusks).
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 Substrate Subclass: Siliceous Ooze – Oozes that are formed primarily from the 

silica-based tests, frustules, or shells of diatoms, radiolarians, or other siliceous 

plankton. Due to the chemistry of deep ocean waters, these are the most abundant 

oozes at ocean depths > 5 kilometers. Carbonate oozes dissolve in the colder, 

more acidic waters that are generally found deeper than 4 or 5 kilometers, but 

siliceous oozes do not dissolve in most ocean waters.

o Substrate Group: Diatomaceous Ooze – Oozes that are formed 

primarily from the silica-based frustules or tests of phytoplanktonic 

diatoms.

o Substrate Group: Radiolarian Ooze – Oozes that are formed primarily 

from the silica-based tests of amoeba-like radiolarians.

Substrate Class: Shell Substrate

Biogenic Substrate that is primarily composed of shells or shell particles. Most (but not 

all) shell-builders are mollusks. 

 Substrate Subclass: Shell Reef Substrate – Substrate that is dominated by living 

or non-living cemented, conglomerated, or otherwise self-adhered shell reefs,

with a median particle size of 4,096 millimeters or greater in any dimension. Live 

reef building fauna may or may not be present; this is described in the BC.

o Substrate Group: Clam Reef Substrate – Shell Reef that is primarily 

composed of cemented or conglomerated clam shells.

 Substrate Subgroup: Coquina Reef Substrate – Shell Reef that 

is primarily composed of cemented or conglomerated Coquina

shells. Living clams may or may not be present: this is described in 

the BC. Note that Coquina shells are described in a separate 

substrate subgroup due to their distinctive features and special 

significance in many areas.

o Substrate Group: Crepidula Reef Substrate – Shell Reef that is 

primarily composed of conglomerated Crepidula shells. While Crepidula

are slowly mobile and do not cement their shells, the gregarious 

settlement of their larvae on conspecifics (Zhao and Qian 2002) can lead 

to very dense accumulations with a flat, reef-like texture as live shells 

build over dead shells.

o Substrate Group: Mussel Reef Substrate – Shell Reef that is primarily 

composed of self-adhered or conglomerated mussel shells. 

o Substrate Group: Oyster Reef Substrate – Shell Reef that is primarily 

composed of cemented or conglomerated oyster shells. 
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 Substrate Subclass: Shell Rubble – Substrate that is dominated by living or nonliving shells forming Rubble, with a median particle size of 64 millimeters to < 

4,096 millimeters in any dimension (Cobbles and Boulders). Particles may be 

either loose, individual shells (whole or broken) or—particularly in the larger

Rubble sizes—cemented, conglomerated, or otherwise attached so as to form 

Boulders of consolidated shell material. The presence of Shell Rubble is noted in 

this subclass (and in the following groups). The presence of living organisms is 

described in the BC.

o Substrate Group: Clam Rubble – Shell Rubble (with a median particle 

size of 64 millimeters to < 4,096 millimeters) that is primarily composed 

of cemented or conglomerated clam shells.

 Substrate Subgroup: Coquina Rubble – Clam Rubble (with a 

median particle size of 64 millimeters to < 4,096 millimeters) that 

is primarily composed of cemented or conglomerated Coquina

shells. 

o Substrate Group: Crepidula Rubble – Shell Rubble (median particle 

sizes from 64 millimeters to < 4,096 millimeters) that is primarily 

composed of conglomerated Crepidula shells. While Crepidula are 

slowly mobile and do not cement their shells, the gregarious settlement of 

their larvae on conspecifics (Zhao and Qian 2002) can lead to very dense 

accumulations as live shells build over dead shells, and sediments fill in 

to bind these areas into flat shelly masses.

o Substrate Group: Mussel Rubble – Shell Rubble (with a median particle 

size of 64 millimeters to < 4,096 millimeters) that is primarily composed 

of self-adhered or conglomerated mussel shells.

o Substrate Group: Oyster Rubble – Shell Rubble (with a median particle 

size of 64 millimeters to < 4,096 millimeters) that is primarily composed 

of cemented or conglomerated oyster shells.

 Substrate Subclass: Shell Hash – Surface substrate layers are dominated by 

loose shell accumulations with a median particle size of 2 millimeters to 

< 64 millimeters (Granules and Pebbles). Shells may be broken or whole. The 

presence of Shell Hash is noted in this subclass (and in the following groups). The 

presence of living organisms is described in the BC.

o Substrate Group: Clam Hash – Shell Hash (with a median particle size 

of 2 millimeters to < 64 millimeters) that is primarily composed of loose 

clam shells and shell bits.

 Substrate Subgroup: Coquina Hash – Shell Hash (with a median 

particle size of 2 millimeters to < 64 millimeters) that is primarily 

composed of loose Coquina shells and shell bits. 
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o Substrate Group: Crepidula Hash – Shell Hash (with a median particle 

size of 2 millimeters to < 64 millimeters) that is primarily composed of 

loose Crepidula shells and shell bits.

o Substrate Group: Mussel Hash – Shell Hash (with a median particle size 

of 2 millimeters to < 64 millimeters) that is primarily composed of loose 

mussel shells and shell bits.

o Substrate Group: Oyster Hash – Shell Hash (with a median particle size 

of 2 millimeters to < 64 millimeters) that is primarily composed of loose 

oyster shells and shell bits.

 Substrate Subclass: Shell Sand – Biogenic Substrate layers that are dominated 

by Sand that is primarily composed of shell particles with a median particle size 

of 0.0625 millimeters to < 2 millimeters (Sand). Shells or remains are generally 

broken and difficult to identify. For this reason, only substrate-forming taxa that 

produce distinctive Sand types are listed as substrate groups. When the 

composition and origin of Sand is unclear, it is assumed to be mineral Sand and is 

classified as a Geologic Origin substrate.

o Substrate Group: Coquina Sand – Shell Sand that is primarily

composed of broken down Coquina shells; this Sand has a characteristic 

orange color. Living clams may or may not be present; this is described 

in the BC.

Substrate Class: Worm Substrate

Biogenic Substrates that are primarily composed of the cemented or conglomerated 

calcareous or sandy tubes of polychaetes or other worm-like fauna. Living or non-living 

worm-tube reefs or worm-tube particles constitute the dominant benthic substrate. The 

presence of Worm Substrate is noted in this class (and in the following subclasses and 

groups). The presence of living organisms is described in the BC. 

 Substrate Subclass: Sabellariid Substrate – Biogenic substrate layers with 

conglomerated structures or smaller particles that are primarily composed of sand 

and shell bits cemented with adhesive proteins into cohesive, clustered tubes by 

sabellariid worms (e.g., Sabellaria or Phragmatopoma).

o Substrate Group: Sabellariid Reef Substrate – Reef that is primarily 

composed of cemented mineral-based or shell-based sabellariid worm

tubes, with a median particle size of 4,096 millimeters or greater in any 

dimension.

o Substrate Group: Sabellariid Rubble – Substrate that is dominated by 

cemented mineral-based or shell-based sabellariid worm tube Rubble, 

with a median particle size of 64 millimeters to < 4,096 millimeters (size 

of Cobbles and Boulders).
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o Substrate Group: Sabellariid Hash – Substrate that is dominated by the 

sand-shell-protein matrix and tubes constructed by sabellariid worms, 

with a median particle size of 2 millimeters to < 64 millimeters (size of 

Granules and Pebbles).

 Substrate Subclass: Serpulid Substrate – Biogenic substrate layers with 

conglomerated structures or broken particles that are primarily composed of 

cemented calcareous worm tubes produced by serpulid worms, e.g., Serpula. 

o Substrate Group: Serpulid Reef Substrate – Reef that is primarily 

composed of cemented or conglomerated calcareous worm tubes, with a 

median particle size of 4,096 millimeters or greater in any dimension.

o Substrate Group: Serpulid Rubble – Substrate that is dominated by 

cemented or conglomerated calcareous worm tube Rubble, derived from 

serpulid worms, with a median particle size of 64 millimeters to < 4,096

millimeters (Cobbles and Boulders).

o Substrate Group: Serpulid Hash – Substrate that is dominated by the 

calcareous tubes of serpulid worms, with a median particle size of 2 

millimeters to < 64 millimeters (Granules and Pebbles).

7.4.3 Substrate Origin: Anthropogenic Substrate

Substrates where percent cover of Anthropogenic Substrate exceeds percent cover of both 

Geologic Substrate and Biogenic Substrates, considered separately. Anthropogenic 

Substrates are classified at the higher levels by composition, and at the lower levels by 

median particle size, using the units Reef Substrate (≥ 4,096 millimeters), Rubble (64 

millimeters to < 4,096 millimeters), Hash (2 millimeters to < 64 millimeters), Sand 

(0.0625 millimeters to < 2 millimeters), and Mud (< 0.0625 millimeters). These units are 

derived from Wentworth (1922), and can be broken down into Wentworth grain size 

classes for greater precision if desired. Shape for this substrate origin is covered in the 

GC, but practitioners may choose to add further descriptors in a comment or notes field. 

Anthropogenic Substrate classifications may be based on percent weight (e.g., for 

retrieved samples); percent cover (e.g., for plan-view images); and visual percent 

composition (for other approaches). The terms “dominant” and “primarily” in the 

Anthropogenic Substrate Origin describe the substrate type that is present in the greatest 

percent cover, greatest percent weight, or greatest visual percent composition. When two 

Anthropogenic Substrate types are present, “dominant” and “primarily” are equivalent to 

“> 50%”. When three or more types exist, the dominant type may occur at a lower 

percent-of-total value. When Anthropogenic Substrate is present, but does not constitute 

the dominant substrate, it should be included as a Co-occurring Element Modifier.

Substrate Class: Anthropogenic Rock

Anthropogenic Substrate that is primarily composed of natural mineral materials that 

were purposefully or accidentally deposited by humans. This includes breakwaters made 
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of natural stone, dredge material, artificial reefs made of natural stone, as well as beach 

nourishment and beach fill. Shape for this substrate class is covered in the GC (e.g., 

Groin, Breakwater, and Dredge Deposit). If the origin of a feature cannot be determined, 

it is assumed to be of natural origin and classified in the Geologic or Biogenic Substrate 

Origin.

 Substrate Subclass: Anthropogenic Rock Reef Substrate – Substrate that is 

dominated by Anthropogenic Rock with a median particle size of 4,096 

millimeters or greater in any dimension.

 Substrate Subclass: Anthropogenic Rock Rubble – Substrate that is dominated 

by Anthropogenic Rock with a median particle size of 64 millimeters to < 4,096 

millimeters (Cobbles and Boulders).

 Substrate Subclass: Anthropogenic Rock Hash – Substrate that is dominated 

by Anthropogenic Rock with a median particle size of 2 millimeters to < 64 

millimeters (Granules and Pebbles).

 Substrate Subclass: Anthropogenic Rock Sand – Substrate that is dominated 

by Anthropogenic Rock with a median particle size of 0.0625 millimeters to < 2 

millimeters.

 Substrate Subclass: Anthropogenic Rock Mud – Substrate that is dominated by 

Anthropogenic Rock (mineral particles) with a median particle size of less than 

0.0625 millimeters.

Substrate Class: Anthropogenic Wood

Anthropogenic Substrate that is primarily composed of woody materials that were 

processed or assembled by humans. Shape for this substrate class is covered in the GC 

(e.g., Jetty, Dolphin, Pilings, and Wreck).

 Substrate Subclass: Anthropogenic Wood Reef Substrate – Substrate that is 

dominated by Anthropogenic Wood with a median particle size of 4,096 

millimeters or greater in any dimension.

 Substrate Subclass: Anthropogenic Wood Rubble – Substrate that is 

dominated by Anthropogenic Wood with a median particle size of 64 millimeters

to < 4,096 millimeters.

 Substrate Subclass: Anthropogenic Wood Hash – Substrate that is dominated 

by Anthropogenic Wood with a median particle size of 2 millimeters to < 64 

millimeters.

Substrate Class: Construction Materials

Anthropogenic Substrate that is composed of any single construction material or

combination of construction materials (concrete, brick, rebar, pipe, porcelain, fiberglass, 

rubber, plastic, < 50% wood, < 50% metal, etc.) that were manufactured by humans. This 
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substrate may be composed of one or many types of these materials. If anthropogenic 

wood or metal constitute a dominant fraction of the materials, the substrate is classified 

as Anthropogenic Wood or Metal, accordingly. Shape for this substrate class is covered 

in the GC (e.g., Breakwater, Wreck (if fiberglass, ferrocement, etc.).

 Substrate Subclass: Construction Reef – Substrate that is dominated by 

Construction Materials with a median particle size of 4,096 millimeters or greater 

in any dimension.

 Substrate Subclass: Construction Rubble – Substrate that is dominated by 

Construction Materials with a median particle size of 64 millimeters to 

< 4,096 millimeters.

 Substrate Subclass: Construction Hash – Substrate that is dominated by 

Construction Materials with a median particle size of 2 millimeters to 

< 64 millimeters.

Substrate Class: Metal

Anthropogenic Substrate that is dominantly composed of metal that was manufactured by 

humans. Shape for this substrate class is covered in the GC (e.g., Cable Area, Wreck [if 

metal]).

 Substrate Subclass: Metal Reef – Substrate that is dominated by Metal with a 

median particle size of 4,096 millimeters or greater in any dimension.

 Substrate Subclass: Metal Rubble – Substrate that is dominated by Metal with a 

median particle size of 64 millimeters to < 4,096 millimeters.

 Substrate Subclass: Metal Hash – Substrate that is dominated by Metal with a 

median particle size of 2 millimeters to < 64 millimeters.

Substrate Class: Trash

Anthropogenic Substrate that is usually composed primarily of plastics but may include 

other trash materials (waxed paper, paper, < 50% metal, rubber, glass, cardboard, tires) 

that were manufactured by humans.

 Substrate Subclass: Trash Rubble – Substrate that is dominated by plastics 

and/or other trash materials with a median particle size of 64 millimeters to < 

4,096 millimeters.

 Substrate Subclass: Trash Bits – Substrate that is dominated by plastics and/or 

other trash materials with a median particle size of 2 millimeters to < 64 

millimeters.
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7.5 Status of Substrate Component Units

The SC units in the Geologic Substrate Origin have been well-tested and much-used over 

decades of application by the marine science community. CMECS modifications to these 

units are minor, and the Geologic Substrate Origin is considered to be robust. Units in the 

Biogenic Substrate Origin are an alignment of commonly used terms (Sand, Hash, 

Rubble, and Reef) with Wentworth size classes. These size/term definitions have not 

been extensively tested, and the Biogenic Substrate Origin terms are not as robust as the 

Geologic terms. The Anthropogenic units presented in this Section should be considered 

an initial attempt to classify Anthropogenic Substrates, focused on those substrates that 

are most common in coastal and oceanic waters.

7.6 Substrate Component Modifiers

The Substrate Component can be enhanced by a number of Modifier terms (see Section

10). 

 Anthropogenic Modifiers

o Anthropogenic Impacts

 Physical Modifiers

o Energy Intensity

o Seafloor Rugosity

o Small-scale Slope

o Tidal Range

o Substrate Descriptors

o Substrate Layering

o Surface Pattern

 Physicochemical Modifiers

o aRPD

o RPD

 Spatial Modifiers

o Benthic Depth Zones

o Co-occurring Elements

o Coral Reef Zone

o Fine Percent Cover

o Coarse Percent Cover 

 Temporal Modifiers

o Temporal Persistence
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8. Biotic Component

The Biotic Component (BC) of CMECS is a classification of the living organisms of the 

seabed and water column together with their physical associations at a variety of spatial 

scales. The BC is organized into a branched hierarchy of five nested levels: biotic setting, 

biotic class, biotic subclass, biotic group, and biotic community (Table 8.1). The biotic 

setting indicates whether the biota are attached or closely associated with the benthos or 

are suspended or floating in the water column. Biotic classes and biotic subclasses 

describe major biological characteristics at a fairly coarse level. Biotic groups are 

descriptive terms based on finer distinctions of taxonomy, structure, position, 

environment, and salinity levels. Biotic communities are descriptions of repeatable,

characteristic assemblages of organisms. In the absence of complete species association 

data, biotic communities can be approximated using dominant or diagnostic species and 

then refined once more information is available. When identified in the context of 

repeating environmental circumstances, biotic communities can be used as the basis for 

defining and fully describing biotopes. A biotope assigns a more complete description of 

the feature; involving all other applicable components of CMECS, listing the defining 

species and explaining the ecological and societal values of the biotope (see Section 9).

Unless otherwise noted, biotic classification units in the BC are defined by the dominance 

of life forms, taxa, or other classifiers in an observation. For collected observations (such 

as grab samples or cores), dominance is measured in terms of biomass or numbers of 

individuals, as specified by the user. In the case of images and visual estimates, 

dominance is assigned to the taxa with the greatest percent cover in the observational 

footprint. For example, an observation with 60% seagrass, 20% soft corals, and 20% 

sponges is classified as an Aquatic Vegetation Bed—whereas an observation with 60% 

soft corals, 20% seagrass, and 20% sponges is classified as a Faunal Bed. It may be 

important for some users to note the presence of the non-dominant biota, which can be 

achieved by using a Co-occurring Element in an observation. See Section 10 for 

information about how to note Co-occurring Elements and Associated Taxa.

Table 8.1. Biotic Component Classification Structure.

Biotic Component

Biotic Setting

 Biotic Class

 Biotic Subclass

 Biotic Group

 Biotic Community
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8.1 Hierarchical Structure

8.1.1 Biotic Setting

The biotic setting separates organisms that live in or are closely associated with the 

bottom (Benthic Biota) from those organisms that are suspended in the water column or 

floating on the surface (Planktonic Biota). Benthic Biota units are defined by species that 

are fixed to the benthos and those that are slow moving (such that they cannot move 

beyond the unit boundary within one day). Planktonic Biota units are defined by 

organisms that passively float or drift through the water column (such as plankton, 

microbes, algae, and jellyfish). Free-swimming organisms (such as fishes, squids, or 

marine mammals that can actively move through the water column) are not used to define 

either biotic setting.

8.1.2 Biotic Class and Subclass

Biotic classes and subclasses are determined by the dominant percent cover based on the 

taxonomy and life forms of the living components of the sampled area. Biotic class 

definitions are based on the biologically defined classes of the Classification of Wetlands 

and Deepwater Habitats in the United States, FGDC-STD-004 (FGDC 1996b). CMECS

Reef Biota, Emergent Wetland, Scrub-Shrub Wetland, and Forested Wetland definitions 

are equivalent to those in FGDC-STD-004, and the CMECS classes for Aquatic 

Vegetation Bed and Moss and Lichen Communities are nearly so (see Appendix G for a 

detailed comparison). These classes have stood the test of time, and they are ecologically 

meaningful and easily distinguishable units (FGDC-STD-004). However, CMECS BC 

also includes several classes that were not part of the FGDC-STD-004 (or were not 

treated at the class level): Zooplankton, Floating/Suspended Plants and Macroalgae, 

Phytoplankton, Floating/Suspended Microbes, Faunal Bed, and Microbial Communities.

In classifying reef-building biota, BC classes use similar terms as the Geoform 

Component (GC) and the Substrate Component (SC). The GC terms refer to the 

structures that are created by the reef-building organisms (which may or may not still be 

present), while the SC describes the composition of the reef substrate itself. BC terms 

describe the live organisms that are currently found on those structures. The GC term reef

is used to refer to the structure. The SC term reef substrate is used to describe the nature 

of the substrate. The BC term reef biota is used to refer to the biotic characteristics of a 

given reef structure.

Biotic subclasses are based on finer distinctions of dominant life forms, taxa, and growth 

forms. For the classes noted above as the same (or nearly so) as those in FGDC-STD004, CMECS subclasses have similarities. The CMECS subclasses for the Reef Biota and

Aquatic Vegetation Bed classes are the same as those in FGDC-STD-004. However, for 

the three CMECS wetland biotic classes, the term tidal is used in the subclasses as the 

main classifier to explicitly exclude FGDC-STD-004 Palustrine, non-tidal riverine, and 

non-tidal wetlands—because they fall outside of the domain of CMECS.
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8.1.3 Biotic Group

Biotic groups are observational, descriptive, or functional groupings of the characteristic 

biological types that occur as generalized patterns across their range. The biotic group

level is designed for widespread use among different regions and for use with a variety of 

sampling methods. Biotic groups are designed as simple observational units, to be based 

upon regularly recurring biological features that are evident in the environment under 

observation. Biotic groups are intended to be identifiable using visual methods at 

appropriate scales. Identification of biology at this level does not require (a) written 

descriptions of ecoregion-specific biological and physical associations, (b) a statistical 

treatment of biotic relationships and co-occurrences, or (c) identification of diagnostic 

taxa to the species level.

The biotic group level is quite useful in many areas—and it is particularly applicable to 

many of the poorly described, soft-sediment habitats that constitute the major part of the 

seafloor. Biological classifications at this level are predictable, with regularly occurring 

physical and biological associations that are highly comparable among different studies 

and regions. Biotic groups can be used for research purposes and to set management 

goals. A significant portion of mapping surveys use optical imaging as one of the primary 

fine-scale sampling tools, and most biotic groups can be determined using visual methods

(e.g., high-resolution, plan-view camera images, video camera images, sediment profile 

images, and diver surveys). Because the biotic classification is hierarchical, a broad 

imaging survey that identifies biotic groups can be accompanied by a more detailed,

collection-based survey to (a) determine biotic communities (see below) and (b) improve 

understanding of biological and physical associations and interactions that will be 

important for defining biotopes (see Section 9).

8.1.4 Biotic Community

A biotic community is a repeatable grouping of species that is relatively uniform in 

structure, species composition, and habitat conditions (Olenin and Ducrotoy 2006,

Hiscock and Tyler-Walters 2003). Biotic communities can be identified observationally, 

or (ideally) as statistically repeating species assemblages across their range of occurrence. 

The assemblage can be identified by diagnostic organisms that are dominant, highly 

constant, or otherwise distinctive. These diagnostic organisms are always fixed (or very 

slow moving), and they can include plants, algae, attached sessile fauna, unattached (but 

relatively non-motile or slowly moving) fauna, infauna, and bacterial colonies. Typically, 

one or two taxa are used to name a biotic community. For habitats dominated by 

vegetation (such as mangroves, coastal marshes and seagrass beds), the biotic community

is equivalent to the association level of the National Vegetation Classification Standard, 

FGDC-STD-005-2008 (FGDC 2008). An association is defined by FGDC-STD-005-

2008 as: “A vegetation classification unit... defined on the basis of a characteristic range 

of species composition, diagnostic species occurrence, habitat conditions and 

physiognomy (Jennings et al. 2006). 
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While the biotic community may be named by one (or a few) dominant or diagnostic 

species (or by genera where the taxonomy of the group is not well known), as an entity 

the community includes all of the associated, regularly occurring taxa that fill its many 

trophic and ecological niches. Biotic communities may be limited to specific geographic 

areas by the distributions of the associated species―some biotic communities may occur 

in only one ecological region, while others may occur across widespread geographic 

areas.

The process of defining biotic communities ideally relies upon rangewide analysis of 

field-collected specimens or species lists from areas that are relatively homogeneous in 

composition and structure. In practice, data on species assemblages across their range are 

currently largely unavailable for most biotic communities. In the absence of such data, 

practitioners may approximate biotic communities by identifying dominant or known 

diagnostic taxa (ideally genera or species). Most of the animal-dominated biotic 

communities currently listed in CMECS use the dominant taxa approach. Over time, as 

the knowledge of these assemblages increases, they will be refined, and replaced with 

biotic communities or biotopes.

To be classified as a given biotic community, observations in the field must verify 

aggregations or assemblages of dominant or characteristic species that are known to 

occur in other locations. An observation of a single individual of a species is not 

considered a biotic community unless there is some evidence that other individuals from 

the assemblage are present. 

In many cases, specific mobile predators are associated with a certain biotic community

(or a set of biotic communities). These predators may range from starfish (on coral reefs)

to wolf eels (on mussel beds). These predatory organisms are not used to define the biotic 

community, which is characterized at the more stable, lower level of the trophic web 

(coral reef or mussel bed); however, common predators are considered as associates and 

they are included in the biotic community descriptions. The presence of distinctive 

organisms (such as larger, mobile predators) other than those used to define the biotic 

community may also be captured as a modifier (Co-occurring Elements or Associated 

Taxa) when describing an observational or reporting unit.

8.2 Biotic Component Units

The BC units are defined below. All faunal and non-vascular biotic communities listed 

below are examples of broad dominance types that are known to occur within a given 

Biotic Group. See Appendix E for a list of the units and Section 10 for relevant modifiers. 

8.2.1 Biotic Setting: Planktonic Biota

Planktonic Biota includes biota that drift, float, or remain suspended in the water column 

in aggregations that are big enough to be (a) detected by the human eye (or with mild 

magnification) or (b) sampled with a fine-plankton net. Planktonic biota are not regularly 
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associated with the seafloor. Water parcels may be examined for plankton using a dipnet, 

a water sampler, a towed plankton net, imagery (including “Plankton Cameras” that are 

moved through the water), or other means. In all cases, plankton are assigned 

classifications based on perceived dominance by the observer (either based on mass or 

numbers, as specified by the user/observer). Because most plankton communities are 

mixes of many types of zooplankton and phytoplankton, practitioners should consider the 

widespread use of the Co-occurring Elements modifier (when non-dominant taxa are 

covered in other parts of the CMECS classification) or the Associated Taxa modifier 

(when non-dominant taxa do not constitute a CMECS classification unit).

Biotic Class: Zooplankton

Water parcels or layers in which zooplankton are perceived to be the dominant feature. 

Zooplankton are heterotrophic biota of the water column; zooplankton drift with the 

currents, but may (or may not) be able to move through the water under their own power. 

Zooplankton may feed on phytoplankton, other zooplankton, or on detritus. CMECS 

classifies zooplankton that may range in size from gigantic salp chains (strings of 

gelatinous filter feeding tunicates that attain a length of 30 meters or more), to 

radiolarians (minute, shelled amoebas). CMECS was not designed to be used for the 

smallest planktonic forms (nanoplankton or picoplankton). CMECS Class Zooplankton 

includes both Holoplankton (that live out their entire life histories in the plankton) and 

Meroplankton (that are transient in the plankton). Meroplankton are typically larval 

stages that develop into nekton or benthos as they mature. Meroplankton in general are 

difficult to identify; specialized taxonomic knowledge and sets of regional keys are 

generally required. Both Holoplankton and Meroplankton are quite diverse and include 

members of most marine phyla.

Aggregations of specific types of zooplankton (or of mixed zooplankton/phytoplankton 

communities) may occur in many forms. In general, an “Aggregation” is a relatively 

dense and homogeneous group of plankton that may be produced by rapid reproduction 

in-place under favorable conditions (by phytoplankton and holoplankton), by 

hydrodynamic forcing, by a common mass origin, by plankton motility (e.g., diurnal 

vertical migrations), by barriers to movement (e.g., pycnoclines), or by other phenomena. 

A Spawning Aggregation forms after a mass spawning event when synchronous 

spawning by many individuals produces large pulses of gametes and larvae. 

Classification of a Spawning Aggregation requires some evidence of recent mass 

spawning. Aggregations of all types may occur as amorphously shaped packets of water, 

may occur in layers at various depths, and may occur as diurnal migrations, among other 

forms.

 Biotic Subclass: Crustacean Holoplankton – Water parcels in which crustacean 

holoplankton are the perceived dominant feature. Crustaceans constitute the vast 

bulk of zooplankton in many areas of the ocean.

o Biotic Group: Amphipod Aggregation – Water parcels in which 

amphipods (laterally compressed or stick-like, elongated, generally small 

crustaceans) aggregate and are the dominant form of zooplankton.
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 Biotic Communities: e.g. Hyperia Aggregation, Caprellid 

Aggregation

o Biotic Group: Copepod Aggregation – Water parcels in which copepods 

aggregate and are the dominant form of zooplankton. Planktonic 

copepods are thought to be among the most abundant multi-cellular 

animals on Earth. Most planktonic copepods use their large antennae to 

move in a series of jerky motions.

 Biotic Communities: e.g. Acartia Aggregation, Calanus 

Aggregation

o Biotic Group: Krill Aggregation – Water parcels in which shrimp-like 

krill constitute the dominant form of zooplankton. Most krill species are 

filter feeders, with a preference for diatoms. Biomass per square meter 

can be very high in krill aggregations, and they are a critical food source 

for many large consumers.

 Biotic Communities: e.g., Euphausia Aggregation, Thysanoessa 

Aggregation

 Biotic Subclass: Crustacean Meroplankton – Water parcels in which 

crustacean meroplankton are the perceived dominant feature. These zooplankters 

typically go through several very different larval stages, and can be difficult to 

identify.

o Biotic Group: Decapod Larval Aggregation – Water parcels in which 

crab, shrimp, and lobster larvae aggregate and are the dominant form of 

zooplankton.

 Biotic Communities: e.g., Brachyuran Crab Larval Aggregation, 

Anomuran Crab Larval Aggregation, Pandalus Larval Aggregation

o Biotic Group: Mixed Crustacean Larvae – Water parcels in which 

several forms of crustacean larvae are mixed, and together they constitute 

the dominant form of zooplankton. This biotic group is meant to be used 

for mixes where it is very difficult to identify a dominant Crustacean 

genus or species. 

 (No Biotic Communities)

 Biotic Subclass: Coral Meroplankton – Water parcels in which coral larval lifehistory stages are the perceived dominant feature. This generally occurs during 

and after synchronous spawning events in reef areas with high coral biomass.

o Biotic Group: Coral Spawning and Larval Aggregation – Water 

parcels in which coral gametes and larvae are aggregated during and after 
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simultaneous spawning (often in astronomical numbers). In events that 

involve synchronous spawning of multiple species of corals, the concept 

of species-specific or group-specific biotic communities (below) may not 

apply, and the feature is identified at the biotic group level.

 Biotic Communities: e.g., Acroporid Spawning Aggregation, 

Montastraea Spawning Aggregation

o Biotic Group: Coral Larval Aggregation – Water parcels in which coral 

larvae aggregate post-spawning, with no evidence of a recent spawning 

event, and they are the dominant form of zooplankton.

 Biotic Communities: e.g., Acroporid Larval Aggregation, 

Montastraea Larval Aggregation

 Biotic Subclass: Echinoderm Meroplankton – Water parcels in which 

echinoderm larvae are the perceived dominant feature. Echinoderms go through 

distinctive larval stages, most of which are characterized by different series of 

ciliated bands that are arranged with bilateral symmetry. Each echinoderm group 

features different larval forms (e.g., pluteus larvae or bipinnaria larvae).

o Biotic Group: Mixed Echinoderm Larval Aggregation – Water parcels 

in which these larval forms aggregate and are the dominant form of 

zooplankton.

 Biotic Communities: Ophiuroid Larval Aggregation, Asteroidean 

Larval Aggregation, Holothurian Larval Aggregation

 Biotic Subclass: Fish Meroplankton – Water parcels in which fish 

meroplankton are the perceived dominant feature. Fish go through several larval 

stages as they progress from embryo to juvenile. Unlike many phyla, most of 

these stages do bear some resemblance to the adult (they are fish-like); 

nonetheless, the taxonomy of fish larvae is a specialized skill.

o Biotic Group: Fish Spawning and Larval Aggregation – Water parcels 

in which fish gametes and larvae are aggregated (often in large numbers) 

after simultaneous spawning, and are the dominant form of zooplankton.

 Biotic Communities: e.g., Damselfish Spawning and Larval 

Aggregation, Grouper Spawning and Larval Aggregation, 

Surgeonfish Spawning and Larval Aggregation

o Biotic Group: Fish Larval Aggregation – Water parcels in which fish 

larvae aggregate and are the dominant form of zooplankton.

 Biotic Communities: e.g., Clupeid Larval Aggregation, Engraulid 

Larval Aggregation, Sciaenid Larval Aggregation
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 Biotic Subclass: Gelatinous Zooplankton – Water parcels in which gelatinous 

zooplankton (generally transparent, often quite large organisms, in which water 

constitutes a very high percentage of the body mass) are the perceived dominant 

feature. Most gelatinous zooplankton are predators on other zooplankton.

o Biotic Group: Ctenophore Aggregation – Water parcels in which 

ctenophores aggregate so as to constitute the dominant form of 

zooplankton. Ctenophores are small, gelatinous, ciliated animals with a 

generally rounded or lobed form. Two retractable feeding tentacles may 

also be present. 

 Biotic Communities: e.g., Beroe Aggregation, Mnemiopsis

Aggregation, Pleurobrachia Aggregation

o Biotic Group: Jellyfish Aggregation – Water parcels in which jellyfish 

(free-swimming Medusozoan life-history stages) aggregate and are the 

dominant form of zooplankton. Most jellyfish are predators, and many 

have venomous nematocysts (stinging capsules in specialized cells).

 Biotic Communities: e.g., Aurelia Aggregation, Chrysaora

Aggregation

o Biotic Group: Salp Aggregation – Water parcels in which salps (bag-like

gelatinous filter-feeding tunicates) aggregate and are the dominant form 

of zooplankton. Many salps grow in a chain formation that can consist of 

100 individuals or more, sometimes reaching 30 meters or greater in 

length, although much shorter chains are more common.

 Biotic Communities: e.g., Thalia Aggregation, Pegia Aggregation

o Biotic Group: Siphonophore Aggregation – Water parcels in which 

these jellyfish-like animals aggregate and are the dominant form of 

zooplankton. Siphonophores are colonies of many individual animals 

(polyps) that are each specialized for various roles (stinging tentacles, 

locomotion, and digestion) but appear and function as a single animal. 

Siphonophores are important predators on other zooplankton and small 

fishes. Most siphonophores are actively mobile, but the best-known 

siphonophore (the Portuguese man-of-war, Physalia) drifts with the wind 

using a gas-filled sac.

 Biotic Communities: e.g., Bargmannia Aggregation, Nanomia

Aggregation, Physalia Aggregation
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Figure 8.1. Siphonophore, Physalia sp.

Dominican Republic (Image: G. Cicchetti).

 Biotic Subclass: Mixed Zooplankton – Water parcels in which complex mixes 

of zooplankton are the perceived dominant feature.

o Biotic Group: Mixed Zooplankton Aggregation – Water parcels in 

which several phyla exist, with no clear dominant taxon. Biotic 

Communities are described by listing abundant or potentially dominant 

taxa.

 Biotic Communities: e.g., Chaetognath, Salp, and Fish Larval 

Aggregation; Ctenophore, Worm and Copepod Aggregation

 Biotic Subclass: Molluscan Holoplankton – Water parcels in which mollusk 

holoplankton are the perceived dominant feature. Certain molluscan taxa with 

reduced shells exist entirely in the plankton.

o Biotic Group: Pteropod Aggregation – Water parcels in which pteropod 

mollusks (characterized by a reduced shell and an expansive, wing-like 

foot) are the dominant form of zooplankton. They are sufficiently 

abundant in some areas of the ocean that their dead shells form ooze after 

sinking to the seafloor.

 Biotic Communities: e.g., Carolla Aggregation, Clione

Aggregation

 Biotic Subclass: Molluscan Meroplankton – Water parcels in which molluscan 

larvae are the perceived dominant feature.

o Biotic Group: Veliger Aggregation – Water parcels in which veligers or 

pedi-veligers (the distinctive larvae of many mollusks) are the dominant 

form of zooplankton. Veligers are characterized by ciliated lobes attached 

to a formative shell and body. 
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 Biotic Communities: e.g., Bivalve Veliger Aggregation, 

Gastropod Veliger Aggregation

 Biotic Subclass: Protozoan Holoplankton – Water parcels in which singlecelled protozoans are the perceived dominant feature. CMECS considers only the 

larger, visible protozoans that form tests or shells.

o Biotic Group: Foraminiferan Aggregation – Water parcels in which 

these numerous protists aggregate and are the dominant form of 

zooplankton. Most planktonic foraminifera are amoeboids that live in a 1 

millimeter to 2 millimeters calcium carbonate test that is composed of 

several growth chambers. Amoeboid pseudopods extend through holes in 

the test.

 Biotic Communities: e.g., Globigerina Aggregation Layer

o Biotic Group: Radiolarian Aggregation – Water parcels in which 

radiolarians (amoeboid protists living in an intricate silica test) aggregate 

and are the dominant form of zooplankton. Radiolarians are particularly 

abundant in equatorial regions of the oceans.

 Biotic Communities: e.g., Acantharea Aggregation, Polycistina

Aggregation 

 Biotic Subclass: Worm Holoplankton – Water parcels in which various

holoplanktonic worm phyla are the perceived dominant feature.

o Biotic Group: Chaetognath Aggregation – Water parcels in which 

chaetognaths aggregate and are the dominant form of zooplankton. 

Chaetognaths are small, fish-shaped worms with large “teeth,” and they 

are ferocious predators. They are commonly known as Arrow Worms.

 Biotic Communities: e.g., Flaccisagitta Aggregation, Sagitta

Aggregation

o Biotic Group: Polychaete Aggregation – Water parcels in which 

holoplanktonic polychaetes (distinctively segmented worms, generally 

with parapodia and setae modified into swimming appendages) are the 

dominant form of zooplankton.

 Biotic Communities: e.g., Syllid Aggregation, Tomopteris

Aggregation

 Biotic Subclass: Worm Meroplankton – Water parcels in which various 

meroplanktonic worm phyla are the perceived dominant feature. Many worm taxa 

spawn planktonic larvae, and identification can be difficult.
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o Biotic Group: Larval Worm Spawning Aggregation – Water parcels in 

which gametes and larvae from various worm taxa are aggregated (often 

in very high abundance) after simultaneous spawning, and they are the 

dominant form of zooplankton. Epitokes may also be present. Epitokes 

are the detachable swimming gonad sections that form the posterior end 

of many species of polychaetes in their pre-breeding stage; these epitokes 

are released during spawning events, and appear as free-swimming 

worms.

 Biotic Communities: e.g., Neanthes Spawning Aggregation, 

Nereid Spawning Aggregation, Palolo (Eunice) Spawning 

Aggregation 

o Biotic Group: Larval Worm Aggregation – Water parcels in which 

larvae of various worm taxa aggregate and are the dominant form of 

zooplankton. Many worm larvae are difficult to identify. The initial larval 

stage of annelids (the rounded, ciliated trochophore stage) is very similar 

to the trochophore stage of larval mollusks. Annelid larvae will continue 

growth by adding segments, however, and become more worm-like.

 Biotic Communities: e.g., Nereid Larval Aggregation, 

Nemeretean Larval Aggregation, Polychaete Larval Aggregation

Biotic Class: Floating/Suspended Plants and Macroalgae

This class includes areas dominated by vascular plants, detached plant parts, or 

macroalgae that are floating on the surface or are suspended in the water column—that is, 

plants and macroalgae that are not rooted or attached to the bottom.

 Biotic Subclass: Floating/Suspended Macroalgae – Areas dominated by 

macroalgae species that are floating on the surface or suspended freely in the 

water column.

o Biotic Group: Algal Rafts – Thick mats composed of macroalgae that 

either float on the surface or are submerged in the water column. Some 

species primarily float (e.g., Kelp Rafts, Rockweed Rafts, and Sargassum 

Rafts), while others may both float and sink (e.g., Gracilaria Rafts and

Ulva Rafts).

 Biotic Communities: e.g., Gracilaria Rafts, Kelp Rafts, 

Rockweed Rafts, Sargassum Rafts, Ulva Rafts

o Biotic Group: Algal Particles – Areas dominated by live drifting or 

floating macroalgae, or macroalgal pieces. They do not form rafts, but 

their distribution in the water column is at a density that can be clearly 

observed with the human eye. 
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 Biotic Communities: e.g., Gracilaria Particles, Kelp Particles, 

Rockweed Particles, Sargassum Particles, Ulva Particles

 Biotic Subclass: Floating/Suspended Vascular Vegetation – Areas dominated 

by vascular vegetation that is floating on the surface or suspended freely in the 

water column. This subclass is limited to freshwater and brackish species. (There 

are no known marine, floating or suspended vascular, plant species.) Vascular 

vegetation that is floating on the surface, but rooted in the substrate is included in 

the Aquatic Vegetation Bed Class.

o Biotic Group: Floating/Suspended Freshwater and Brackish 

Vegetation – Areas dominated by freshwater and brackish vascular 

vegetation that is floating on the surface or suspended in the water 

column.

 Biotic Communities: e.g., Eichornia Mats, Pistia Mats

Biotic Class: Phytoplankton

This class includes areas of floating or suspended microscopic algae that are capable of 

photosynthesis. Although some species are motile, they are generally passively 

transported by water movements. Under certain conditions, they can form aggregations, 

large blooms or colonies.

The spatial and temporal expressions of phytoplankton are described as three types in 

CMECS. (1) Aggregations are detectable concentrations of one or more species within a 

defined volume or area. Aggregations form when conditions are sufficient for growth of 

phytoplankton and are typically represented as mixed aggregations, but often with a 

single species or group predominating. (2) Blooms are defined as rapid growth and 

multiplication of single species to high density in an area of surface waters within a short 

period of time (days), often to the exclusion of other species. Blooms are often 

considered to be harmful to the ecology of the system and may represent an imbalance of 

conditions. (3) Phytoplankton maxima layers are expressed as defined layers of one or 

more species, often with one group predominating, that form at depth within the water 

column, whose thickness is small relative to its areal extent. Maxima layers generally 

occur in response to presence of optimal conditions, such as salinity and temperature or 

the supply of a limiting resource, such as nutrients, for growth along an interface.

 Subclass: Chlorophyte Phytoplankton – Areas dominated by Chlorophytes

(green algae that are unicellular, flagellated, and sometimes colonial 

phytoplankton), occurring more predominantly in the tropics.

o Biotic Group: Chlorophyte Aggregation – Waters dominated by 

Chlorophytes. This group is known to aggregate at frontal zones and 

under ice pack.

 Biotic Communities: e.g., Chlorella Aggregation
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o Biotic Group: Chlorophyte Bloom – Surface waters where rapid growth 

and very high densities of chlorophytes occur, particularly under 

quiescent conditions when nutrients are in excess.

 Biotic Communities: e.g., Pyramimonas Bloom

Biotic Group: Chlorophyte Maximum Layer – Relatively thin layer 

dominated by chlorophytes at depth in the water column where nutrients 

are optimal. Chlorophytes are adapted to low light levels.

 Biotic Communities: e.g., Ostreococcus Maximum Layer

 Biotic Subclass: Chrysophyte Phytoplankton – Waters dominated by 

Chrysophyte Phytoplankton, single-celled algae found mostly in freshwater 

(although several orders occur in brackish and salt water). The pigment 

fucoxanthin gives them a yellow or brown color, and there are a variety of forms 

of the so-called “golden algae,” including plasmoid, amoeba-like, flagellated, 

naked, and silicious.

o Biotic Group: Chrysophyte Aggregation – Waters dominated by 

chrysophytes; these cells can aggregate via mucus excretions that bind 

single cells into colonies, often combined with mineral particles and 

bacterial communities. Chrysophytes occur in coastal waters where 

nutrients and light are sufficient.

 Biotic Communities: e.g., Apindella Aggregation

o Biotic Group: Chrysophyte Bloom – Surface waters where rapid growth 

and very high densities of chrysophytes occur. These organisms form 

brown tide blooms that are common in coastal waters and estuaries and

often damage seagrass beds (by shading).They also may exhibit toxicity 

to grazers and filter feeders.

 Biotic Communities: e.g., Aureococcus Bloom

o Biotic Group: Chrysophyte Maximum Layer – Relatively thin layer

dominated by chrysophytes at depth in the water column; some 

chrysophytes are flagellated and can adjust their position in the water 

column. These and other plankton form maxima at depths where nutrients 

are in optimal concentrations.

 Biotic Communities: e.g., Dinobryon Maximum Layer

 Biotic Subclass Coccolithophore Phytoplankton – Coccolithophores are small 

phytoplankters, predominantly marine, which produce plates of calcium carbonate 

as shells. 
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o Biotic Group: Coccolithophore Aggregation – Waters dominated by

coccolithophores. This group is distributed throughout the oceans and 

tends to have high light requirements, often aggregating in the upper 

water column and surface layer.

 Biotic Communities: e.g., Coccolithus pelagicus Aggregation

o Biotic Group: Coccolithophore Bloom – Surface waters where rapid 

growth and very high densities of coccolithophores occur. These 

organisms form enormous blooms in the coastal and offshore oceans. 

Blooms may be linked to upwelling events.

 Biotic Communities: e.g., Emiliania huxleyi Bloom

o Biotic Group: Coccolithophore Maximum Layer – Relatively thin layer 

dominated by coccolithophores at depth in the water column where 

nutrients are optimal. Coccolithophores are not generally found at depth;

however, when surface nutrients are depleted and the water column is 

clear, some instances of a deeper maximum in the epipelagic layer have 

been noted.

 Biotic Communities: e.g., Crenalithus Maximum Layer

 Biotic Subclass: Cryptophyte Phytoplankton – Waters dominated by 

cryptophytes, a small—but diverse—group of unicellular algae that occur in fresh 

and salt water. Some species are mixotrophic and are able to thrive in low-nutrient 

environments.

o Biotic Group: Cryptophyte Aggregation – Waters dominated by 

aggregations of cryptophytes. Cryptophytes aggregate in waters where 

nutrient concentrations are seasonally in low supply and nutritional needs 

can be met by consuming bacteria. 

 Biotic Communities: e.g., Chrysophaeum Aggregation

o Biotic Group: Cryptophyte Bloom – Surface waters where rapid growth 

and very high densities of cryptophytes occur. Blooms are generally not 

toxic and can form in coastal and estuarine waters. 

 Biotic Communities: e.g., Myrionecta Bloom

o Biotic Group: Cryptophyte Maximum Layer – Relatively thin layer 

dominated by cryptophytes at depth in the water column. Motility allows 

the group to avoid predation and to optimize their heterotrophic grazing.

 Biotic Communities: e.g., Teleaulax Maximum Layer
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 Biotic Subclass: Cyanophyte Phytoplankton – Areas dominated by 

cyanophytes, blue-green algae that are photosynthetic bacteria. Some of these are 

nitrogen fixing, some form resting cysts, and they can exist singly or in colonies.

o Biotic Group: Cyanophyte Aggregation – Waters dominated by 

cyanophytes, which can aggregate under appropriate conditions in both 

coastal and open ocean environments. Those with nitrogen-fixing 

capability have a competitive advantage in nitrogen-poor environments,

and coccoid cyanophytes are often dominant in oligotrophic tropical 

oceans.

 Biotic Communities: e.g., Nodularia Aggregation

o Biotic Group: Cyanophyte Bloom – Surface waters where rapid growth 

and very high densities of cyanophytes occur. Cyanophyte Blooms are 

increasingly common in coastal waters, and can be toxic.

 Biotic Communities: e.g., Synechococcus Bloom

o Biotic Group: Cyanophyte Maximum Layer – Relatively thin layer 

dominated by cyanophytes at depth in the water column. Cyanophytes can 

be found in a maximum layer where nutrients are sufficient (often at the 

base of the nutricline). They are often associated with an oxygen 

maximum layer due to their high rates of photosynthetic production.

 Biotic Communities: e.g., Trichodesmium Maximum Layer

 Biotic Subclass: Diatom Phytoplankton – Waters dominated by Diatom 

Phytoplankton, single-cell algae that circulate passively or sink in the water 

column. This non-flagellated group possesses silica-based frustules that can form 

large and elaborate static appendages. They are considered desirable, high-quality 

food for grazers, supporting healthy food webs.

o Biotic Group: Diatom Aggregation – Waters dominated by diatoms that

aggregate passively during blooms or via exudation of sticky polymers 

that act as glue to bind cells together. (Bacteria may play an important 

role in the binding process.) Diatom aggregations play an important role 

in the marine carbon budget, and since aggregations sink more rapidly 

than single cells, they transport carbon to lower waters and the benthos.

 Biotic Communities: e.g., Thalassiosira Aggregation

o Biotic Group: Diatom Bloom – Surface waters where rapid growth and 

very high densities of diatoms occur. Diatoms are large cells and tend to 

have high nutrient requirements. Spring diatom blooms occur in many 

estuarine and coastal waters, as diatoms have low light requirements and 

are well adapted to the hydrologic period when turbid riverine inputs are 
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highest. They have higher nutrient requirements than other groups and 

require silica, needed to produce frustules. Land runoff contains silica 

making the spring period ideal for formation of coastal diatom blooms. 

The rise of the bloom is important in initiating food webs of zooplankton 

and other grazers and the decay of the bloom is important in nutrient 

cycling, and potentially contributes to the later formation of hypoxic 

bottom water as organic material accumulates in the lower water column.

 Biotic Communities: e.g., Skeletonema Bloom

o Biotic Group: Diatom Maximum Layer – Relatively thin layer dominated 

by diatoms at depth in the water column. Layers of high diatom density

generally form in the surface mixed layer and have also been found at 

deep subsurface maxima. These are associated with nutrient or 

temperature maxima.

 Biotic Communities: e.g., Asterionellopsis Maximum Layer

 Biotic Subclass: Dinoflagellate Phytoplankton – Areas dominated by 

flagellated phytoplankton that have some motility and can control their position in 

the water column to a degree, diurnally migrating from surface to bottom to 

maximize conditions for growth. This group has both photosynthetic and 

heterotrophic species, which play a large role in coastal and estuarine trophic 

dynamics. These phytoplankton also can form noxious and harmful blooms, 

including red tides that may be toxic to higher consumers and to humans. Their 

complex life cycle goes through many stages, which can include resting cysts that

spend prolonged periods in the benthic sediments.

o Biotic Group: Dinoflagellate Aggregation – Waters dominated by 

dinoflagellates that aggregate in coastal and marine waters throughout the 

world. Some evidence suggests that both heterotrophic and mixotrophic 

feeding adaptations supplement autotrophy, giving dinoflagellates a 

competitive advantage over other groups—especially during periods of 

low nutrient availability. Aggregations are responsible for 

bioluminescence, which may reduce predation by disrupting grazers and 

by triggering secondary predators that consume dinoflagellate predators 

(Latz et al. 2004)

 Biotic Communities: e.g., Noctiluca Aggregation

 Biotic Group: Dinoflagellate Bloom – Surface waters where 

rapid growth and very high densities of dinoflagellates occur. 

These blooms have caused a number of problems in coastal waters 

because many species are toxic to consumers. Shellfish and fish 

can accumulate toxins and pass them on to higher trophic levels, 

including humans. 
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 Biotic Communities: e.g., Karenia Bloom

o Biotic Group: Dinoflagellate Maximum Layer – Relatively thin layer 

dominated by dinoflagellates at depth in the water column. 

Dinoflagellates migrate vertically through the water column to layers 

where nutrients and light are optimal for growth. Often the maxima can 

occur at the surface when nutrients are saturating throughout the water 

column. There is also evidence that migration is an adaptive strategy to 

avoid predation (Baek et al. 2011).

 Biotic Communities: e.g., Gymnodinium Maximum Layer

Biotic Class: Floating/Suspended Microbes

Aggregations of microbes that are floating or suspended in the water column and not 

attached to the bottom or to any benthic substrate.

 Biotic Subclass: Films and Strands – Aggregations of microbes in a very thin 

layer (millimeters or less) on the water’s surface or at a discontinuity layer within 

the water column. The air-water interface is a site of intense biological activity 

due to the abundance of light, oxygen and energy. The density gradients and 

discontinuity at the surface of the water column or at fronts and discontinuities 

within the water column are ideal for the aggregation of microbes in films 

covering large areas and strands that follow the movements of water currents 

(Cunliffe and Murrell 2009). The concentration of microbes creates numerous 

niches for feeding by higher trophic levels and for the processing of biogenic and 

inorganic compounds that are important to marine chemistry, including 

controlling carbon, nitrogen and sulfur redox processes (Hansel and Francis 

2006). The film created by microbial concentration also creates a biological 

barrier that can either facilitate or impede transgression of materials across the airwater interface or other layer.

 Biotic Subclass: Microbial Foam – Aggregations of microbes within the foam 

matrix that forms on the water’s surface. Sea foam is the foam the lies on the sea 

surface, in the surf zone and at times on intertidal areas, created from dissolved 

organic compounds when air is forcefully injected into the water column (Harden 

and Williams 1989). Foam formation is aided by properties of lignans, proteins 

and carbohydrates that act as surfactants or foaming agents. The large area 

presented by the micro-bubbles composing seafoam is an ideal surface for 

concentration and adherence of microbial communities including bacteria, viruses 

and microscopic plankton. The characteristics of the air-water interface, and 

particularly of sea foam are unique compared to the bulk water column (Lion and 

Leckie 1981) and possess unique physical and chemical properties. The foams are 

well-oxygenated, sites of photolytic processes and tend to support high levels of 

aerobic metabolism with high organic processing rates. Surface foam is the site of 

intense trophic activity at the microbial level because of the concentration of 

microbial biomass, sugars, lipids and other growth compounds and thus represents 
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an important part of the marine microbial food web. Concentration and 

transformation of trace metals, nutrient compounds, contaminants and pollutants 

also occurs in sea foam and can enter the food web via microbial pathways. The 

properties of the foam have also been identified as delivering growth-promoting 

nutrients and organic material to seagrass and kelp communities.

 Biotic Subclass: Microbial Aggregation – Aggregations of microbes within the 

water column that have detectable, visible color. Microbial communities 

suspended in the water column can reach high concentrations and even be the 

dominant biota in an area, both numerically and in terms of biomass. Suspended 

free-floating microbes, as well as those adsorbed to suspended particulates are 

important in the marine food web. The concentration of bacterial communities has 

been linked to discoloration of the water column (Hansel and Francis 2006) via 

oxidation of molecular compounds in the water, such as manganese and iron.

8.2.2 Biotic Setting: Benthic/Attached Biota

This biotic setting describes areas where biota lives on, in, or in close association with the 

seafloor or other substrates (e.g., pilings, buoys), extending down to include the layers of 

sediment that contain multi-cellular life. As a rule, Benthic/Attached Biota units are 

characterized by the various life histories and taxonomic characteristics of the dominant 

life forms.

Biotic Class: Reef Biota

Areas dominated by reef-building fauna, including living corals, mollusks, polychaetes or 

glass sponges.

In order to be classified as Reef Biota, colonizing organisms must be judged to be 

sufficiently abundant to construct identifiable biogenic substrates. When not present in 

densities sufficient to construct reef substrate, the biota is classified in the Aquatic 

Vegetation Bed or Faunal Bed classes.

The Reef Biota Class refers to only the living component of reef structures. If referring to 

the reef structure, users should use the reef units in the Geoform Component. If referring 

to the composition of the reef substrate independent of the living cover, users should 

employ the Coral Substrate, Shell Substrate, or Worm Substrate Classes in the Substrate 

Component (SC).

 Biotic Subclass: Deepwater/Coldwater Coral Reef Biota – Areas dominated by 

biota closely associated with the structures and settings created by azooxanthellate 

(lacking symbiotic algae), deep-water, stony corals (Order Scleractinia) or 

stylasterid corals (Order Anthoathecatae; Family Stylasteridae). Biotic groups and 

communities for the Deepwater/Coldwater Coral Reef subclass recognize coral 

reef areas as structural settings that were constructed by the framework-forming 

corals. The living coral reef is characterized by the presence of live reef-forming 
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corals, but may or may not be dominated by living corals; other fauna may in fact 

exceed the corals in percent cover. 

The Deepwater/Coldwater Coral Reefs are separated into two Biotic Groups 

based on whether they are formed by stony corals or stylasterid corals. The 

growth forms of those corals and the reefs they create are structurally different. 

Biotic communities are characterized by the dominant species of frameworkforming, deep-sea coral. For example, a Deepwater/Coldwater Lophelia Reef

would be dominated by Lophelia pertusa coral, but may include other stony 

corals such as Madrepora oculata, Enallopsammia rostrata, or Solenosmilia 

variabilis.

o Biotic Group: Deepwater/Coldwater Stony Coral Reef – Areas

dominated by deepwater stony corals. There are 17 known species of 

deepwater, azooxanthellate, stony corals (Class: Anthozoa; Order: 

Scleractinia) that form larger, branching colonies and contribute to reef 

frameworks. Six of these are particularly widespread or important, and 

these are major contributors to the framework of their respective habitats. 

These species form branching colonies (generally less than 1 - 2 meters in 

size), and aggregations of these living colonies—and their immediately 

adjacent dead framework and rubble—are important habitats for 

numerous other sedentary and mobile species.

 Biotic Communities: e.g., Enallopsammia Reef, Goniocorella

Reef, Lophelia Reef, Madrepora Reef, Oculina Reef, Solenosmilia

Reef

o Biotic Group: Deepwater/Coldwater Stylasterid Coral Reef – Areas

dominated by stylasterid corals. A number of stylasterid coral species 

(Class: Hydrozoa; Order: Anthoathecatae; Family: Stylasteridae) form 

smaller branching colonies that can dominate certain habitats, primarily 

in deeper, colder waters. Stylasterid coral reefs often predominate on 

oceanic islands, seamounts, and archipelagos (Cairns 1992).

 Biotic Communities: e.g., Mixed Stylasterid Reef, Stylaster Reef

o Biotic Group: Colonized Deepwater/Coldwater Reef – Areas 

dominated by deepwater reefs where live reef building hard corals are 

present, but not clearly dominant. Cover is dominated by non-reefforming biota, including black corals, gold corals, gorgonians, sponges, 

and other sedentary or attached macro-invertebrates. If no living reefforming corals are present, then the biotic class is Faunal Bed.

 Biotic Communities: e.g., Black Coral Colonized Deepwater/

Coldwater Reef, Gold Coral Colonized Deepwater/Coldwater 

Reef, Gorgonian Colonized Deepwater/Coldwater Reef, Mix 
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Colonized Deepwater/Coldwater Reef, Sponge Colonized 

Deepwater/Coldwater Reef

 Biotic Subclass: Shallow/Mesophotic Coral Reef Biota – Areas with ample 

light that are dominated by hermatypic (reef-building) hard corals or nonhermatypic reef colonizers. 

The Shallow/ Mesophotic Coral Reef Biota are largely based on the growth form 

of the dominant corals that (a) reflect differences in environmental conditions and 

(b) provide varied habitat circumstances (such as increased cover) for associated 

fish and invertebrate species. The same coral species can present different growth 

forms under different environmental circumstances. For example, Acropora sp. 

can have both branching and table growth forms, depending on the environment. 

To reflect the differences in the physical and biological environments, the same 

species may be used to define communities in more than one coral group.

Figure 8.2. Branching Coral Growth Form.

Family Acroporidae, Northwestern Hawaiian Islands. Image: NOAA National Ocean 

Service Education.

o Biotic Group: Branching Coral Reef – Reefs in shallow or mesophotic 

situations dominated by branching corals (includes arborescent, arboreal, 

digitate, corymbose, ramose, and elkhorn corals) that grow in a tree-like 

shape and have numerous branches, some with secondary branches. This 

group includes both fragile, branching corals and more robust, branching 

corals that have exceptionally thick and sturdy antler-like branches (such 
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as elkhorn corals). See Figure 8.2 for an example of the branching coral 

growth form.

 Biotic Communities: e.g., Branching Acropora Reef, Branching 

Madracis Reef, Branching Pocillopora Reef, Porites Reef

o Biotic Group: Columnar Coral Reef – Areas dominated by columnar 

corals that emerge from a massive base in a pillar form and do not 

branch. They are commonly found in mild water flow at mid-depth water 

levels.

 Biotic Communities: e.g., Columnar Dendrogyra Reef, Columnar 

Psammocora Reef

o Biotic Group: Encrusting Coral Reef – Reefs or reef-like, rocky 

structures dominated by encrusting corals (also called crustose corals) 

that (a) cover the substrate in a sheet and (b) expand in diameter rather 

than height. Encrusting corals are highly tolerant of strong water currents,

and they are frequently found on rocky shorelines lacking a beach. See 

Figure 8.3 for an example of the encrusting coral growth form.

 Biotic Communities: Encrusting Millepora Reef, Encrusting 

Porites Reef

o Biotic Group: Foliose Coral Reef – Areas dominated by foliose corals

that have a vase-like structure and whorl-like growth pattern similar to 

the open petals of a flower. The structure of these corals provides shelter 

for fish and invertebrate species. See Figure 8.4 for an example of the 

foliose coral growth form.

 Biotic Communities: Foliose Agaricia Reef, Foliose Milipora 

Reef
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Figure 8.3. Encrusting Coral Growth Form.

Image: NOAA National Ocean Service Education.

Figure 8.4. Foliose Coral Growth Form.

Image: Linda Wade.
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o Biotic Group: Massive Coral Reef – Reefs dominated by massive corals 

(also known as boulder or mound corals) that are characteristically ballor boulder-shaped and relatively slow growing. This group includes reefs 

dominated by submassive corals, which are similar to massive corals, but 

have a lumpier structure. Brain corals are an example of massive coral.

Massive and submassive corals are resistant to strong water currents, and 

are therefore commonly found in shallow and mid-depth waters. These 

forms are common on back-reef slopes. See Figure 8.5 for an example of 

the massive coral growth form.

 Biotic Communities: Massive Diploria Reef, Massive 

Montastraea Reef, Massive Porites Reef

Figure 8.5. Massive Coral Growth Form.

Image: NOAA National Ocean Service Education.

o Biotic Group: Plate Coral Reef – Reefs dominated by plate corals that 

grow in a flattened plate, saucer-like, or thin sheet fashion—often in a 

terraced pattern. Plate corals (also known as laminar, leaf, or sheet corals) 
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usually have thin, disc-shaped colonies with corallites growing only on 

one side. See Figure 8.6 for an example of a plate coral growth form.

 Biotic Communities: Plate Agaricia Reef, Plate Leptoseris Reef, 

Plate Montastraea Reef

Figure 8.6. Plate Coral Growth Form.

Image: www.freeimages.co.uk.

o Biotic Group: Table Coral Reef – Reefs dominated by table corals that 

form platforms that are made up of small, tightly packed branches. Table 

corals are usually found in shallow waters. See Figure 8.7 for an example 

of the table coral growth form.

 Biotic Communities: e.g., Table Acropora Reef

o Biotic Group: Turbinate Coral Reef – Areas dominated by turbinate 

corals that are cone shaped. Turbinate corals are often found in calmer 

water at mid-depth levels, often on back reef-slopes.

 Biotic Communities: e.g., Turbinate Madracis Reef.

o Biotic Group: Mixed Shallow/Mesophotic Coral Reef – Areas where 

multiple coral growth forms are present and none are clearly dominant. 

 Biotic Communities: To be determined.
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Figure 8.7. Table Coral Growth Form.

Image: NOAA National Ocean Service Education.

o Biotic Group: Colonized Shallow/Mesophotic Reef – Tropical coral reef 

substrate where live reef building corals are present, but not clearly 

dominant. Cover is dominated by non-reef-forming corals (such as soft 

corals, gorgonians [e.g., sea fans and sea whips], and sea pansies), 

sponges, other sedentary or attached macro-invertebrates, occasional 

seagrasses, macroalgae, echinoderms, and other reef associates. Reefbuilding, hard corals are present, but not clearly dominant. If no living 

coral is present, then the biotic class if Faunal Bed. 

 Biotic Communities: e.g., Black Coral Colonized Shallow/

Mesophotic Reef, Gold Coral Colonized Shallow/Mesophotic 

Reef, Calcareous Algae Colonized Shallow/Mesophotic Reef, 

Coral Garden Reef, Coralline/ Crustose Algae Colonized 

Shallow/Mesophotic Reef, Gorgonian Colonized Shallow/ 

Mesophotic Reef, Soft Coral Colonized Shallow/Mesophotic Reef, 

Sponge Colonized Shallow/ Mesophotic Reef

 Biotic Subclass: Glass Sponge Reef Biota – Areas dominated by live, deepwater, glass sponges (Order: Hexactinosida) present in densities that are judged 

sufficient to form substrate. These sponges construct a complex siliceous skeleton 

that provides structure and relief on the seafloor, creating habitat for many other 

organisms.
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o Biotic Group: Glass Sponge Reef – Areas dominated by one or more of 

the three species of glass sponges that appear to be the primary 

contributors to the framework of extant glass sponge reefs: Heterochone 

calyx, Aphrocallistes vastus, and Farrea occa. See Figure 8.8 for an 

example of a Glass Sponge Reef.

 Biotic Communities: e.g., Hexactinosida Reef

Figure 8.8. Glass Sponge Reef: Hexactinosida Reef.

Hecate Strait, Canada. Image: Natural Resources Canada.

 Biotic Subclass: Mollusk Reef Biota – Areas dominated by consolidated 

aggregations of living and dead mollusks, usually bivalves (e.g., oysters or

mussels or giant clams) or gastropods (e.g., vermetids) attached to their 

conspecifics and sufficiently abundant to create substrate. 

o Biotic Group: Gastropod Reef – Areas dominated by consolidated 

aggregations of living and dead gastropod mollusks, typically those of the 

Family Vermetidae or the Genus Crepidula. Shells in a “reef” must have 

consolidated or conglomerated into a reef structure with some relief and 

permanence; a reef is more that an accumulation of loose shells. 

Vermetids construct tubes that are cemented to hard substrates and to 

conspecifics, generally in intertidal habitats. Crepidula forms reefs 

through preferential settling of larvae on conspecifics (Zhao and Qian

2002) combined with very limited mobility, and sediment infilling. 

Crepidula reefs are generally flat features with little vertical relief.
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 Biotic Communities: e.g., Crepidula Reef, Vermetid Reef

o Biotic Group: Mussel Reef – Areas dominated by the ridge- or moundlike structures formed by the colonization and growth of mussels that are 

attached to a substrate of live and dead conspecifics. Mussels use byssal 

threads and a powerful glue to tether their shells to a substrate, and their 

reefs also provide valuable habitat and filtration.

 Biotic Communities: e.g., Modiolus Reef, Mytilus Reef

o Biotic Group: Oyster Reef – Areas dominated by the ridge- or moundlike structures formed by the colonization and growth of oysters that are 

attached (cemented) to a substrate of live and dead conspecifics. Oyster 

reefs provide excellent structural habitat as well as effective water 

filtration. 

 Biotic Communities: e.g., Crassostrea Reef, Ostrea Reef

 Biotic Subclass: Worm Reef Biota – Areas dominated by relatively stable,

ridge- or mound-like aggregations of living and non-living material formed by the 

colonization and growth of worm species (e.g., sabellariids).

o Biotic Group: Sabellariid Reef – Areas dominated by ridge- or moundlike features formed by the colonization and growth of living sabellariid 

worm species that have cemented sediment grains into complex 

structures. Certain types of sabellariid reefs most often occur parallel to 

an ocean shoreline in shallow water, but many are also found in deeper 

waters where current energy is high.

 Biotic Communities: e.g., Phragmatopoma Reef, Sabellaria Reef 

o Biotic Group: Serpulid Reef - Areas dominated by mound-like, bushlike, or patchy growths of living Serpulid worms that have secreted tubes 

of calcium carbonate to form complex aggregated structures. Serpulid 

worms can be distinguished from Sabellariid worms (see above) by the 

presence of a hard operculum that seals the hard, shell-like Serpulid tube. 

Living Serpulid reefs are extremely rare in U.S. coastal waters, but 

recently extinct Serpulid reef structures do occur, e.g., in certain Gulf of 

Mexico embayments. If no living Serpulid worms are present and the 

reef is extinct, it is classified in CMECS as Substrate (see Section 7.4.2). 

Living Serpulid reefs are, however, found in other parts of the world, and 

are considered valuable structure-forming habitat.

 Biotic Communities: e.g., Serpula vermicularis Reef
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Biotic Class: Faunal Bed

Seabeds dominated or characterized by a cover of animals that are closely associated with 

the bottom, including attached, clinging, sessile, infaunal, burrowing, laying, interstitial, 

and slow moving animals, but not animals that have created substrate (Reef Biota). 

Unlike Reef Biota, Faunal Bed biota cannot (or are not sufficiently abundant to) construct 

identifiable substrate. “Slow moving” animals included in the Faunal Bed class are 

defined as being incapable of moving outside the boundaries of the classification unit 

within one day. Faunal Bed organisms are aquatic, but they may be able to withstand 

periods of exposure to air. 

Faunal Bed food webs may receive basic trophic inputs from benthic photosynthesis or 

chemosynthesis, plankton, allochthonous detritus and debris, or other sources. In nature, 

Faunal Bed habitats are often composed of complex mixes and associations of animals of 

different phyla, sizes, feeding strategies, and habits, and these areas can be difficult to 

classify. Faunal Bed classifications are determined in CMECS by greatest percent cover 

of fauna or faunal structures, or (particularly for infauna) by estimates of greatest 

biomass. The inherent complexity of these areas is addressed through Co-occurring 

Elements and Associated Taxa Modifiers (Sections 10.6.2 and 10.3.1).

In the photic zone, primary producers often constitute the greatest biotic percent cover of 

substrate, and so define the biotic group of an area (e.g., Filamentous Algal Bed, 

Microphytobenthos). Faunal Bed organisms, when present in these areas, are classified in 

CMECS as Co-occurring Elements, for example: “Biotic Group: Coralline/Crustose 

Algal Bed with Co-occurring Element: Attached Strongylocentrotus purpurata”.

In waters deeper than the photic zone, however, most Faunal Bed biotic groups and 

communities are defined by immobile or slow-moving suspension-feeders and 

detritivores that dominate percent cover or biomass, and create a distinct living 

environment for other fauna. Other Faunal Bed biotic groups and communities are 

defined by slow-moving grazers or predators (e.g., urchins, starfish), when these are the 

clearly dominant fauna. However, practitioners should attempt to identify a biotic group 

that is providing “forage” for these predatory or herbivorous species. If a “forage” 

biotope is present, it will often dominate percent cover, and practitioners should 

characterize the area accordingly as (for example): “Biotic Community: Nassariid Bed

with Co-occurring Element: Pisaster”. The Co-occurring Elements modifier (see Section 

10.6.2) is used to describe areas where any two (or more) biotic groups, biotic 

communities, or other biotic classification units described in CMECS occur 

simultaneously. In these cases, the classification units exist together, as a mix, in a single 

location, and the non-dominant units are termed Co-occurring Elements. Further local 

research may indicate that the mix of biotic groups and co-occurring elements is, in fact, 

a repeatable unit that should be designated as a single defined biotic group or biotope.

Other common animals in seafloor environments include opportunistic predators or 

herbivores that are capable of moving outside the bounds of the classification unit within 

one day, such as portunid crabs, cancrid crabs, horseshoe crabs, cephalopods, other 

mobile benthic crustaceans, fishes, and other nekton. These animals actively move over 
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the seafloor searching for prey, and are defined in CMECS as Associated Taxa (see 

Section 10.3.1).

As in other BC classes, practitioners may apply Genus and/or species names to define

local biotic communities that are not listed in the current version of CMECS. In these 

cases, observations in the field must verify that these new biotic communities are 

predictable and repeating aggregations or assemblages of dominant or characteristic 

species. These names should be submitted as part of the CMECS Dynamic Content 

Standard (see Section 13).

Faunal Beds are highly dependent on substrate type. Individual species and entire biotic 

communities have adapted specialized anatomies and behaviors for survival on hard 

substrates; other species and communities have specialized and developed adaptations for 

life on soft substrates. Generalist fauna also occur (e.g., certain holothurians, 

crustaceans, and sponges) that can succeed on both substrate types. However, substrate 

type is such a defining aspect of the Faunal Bed class that CMECS Faunal Bed subclasses 

are assigned as physical-biological associations involving both biota and substrate. 

The Faunal Bed class is arranged into two major subclasses: Attached Fauna, and Soft 

Sediment Fauna. Each subclass presents alphabetized biotic groups that are defined by 

ecological characteristics, followed by alphabetized biotic groups that are defined by 

taxonomic characteristics. Fauna that fit into two biotic groups are generally assigned to 

the group that provides the most ecological detail; e.g., Serpulorbis (an attached tube 

builder and a sessile gastropod) is placed in Attached Tube-Building Fauna, not Sessile 

Gastropods. Names of biotic communities from soft sediment faunal areas incorporate the 

term “Bed” to distinguish them from hard sediment (attached) faunal communities. 

 Biotic Subclass: Attached Fauna – Areas characterized by rock substrates,

gravel substrates, other hard substrates, or mixed substrates that are dominated by 

fauna which maintain contact with the substrate surface, including firmly 

attached, crawling, resting, interstitial, or clinging fauna. Fauna may be found on, 

between, or under rocks or other hard substrates or substrate mixes. These fauna 

use pedal discs, cement, byssal threads, feet, claws, appendages, spines, suction, 

negative density, or other means to stay in contact with the (generally) hard 

substrate, and may or may not be capable of slow movement over the substrate. 

However, these fauna are not able to achieve speeds sufficient to move beyond 

the unit boundary within one day. Many attached fauna are suspension feeders 

and feed from the water column. Other attached fauna are benthic feeders, 

including herbivores, predators, detritivores, deposit feeders, and omnivores. 

Within Attached Fauna, the Biotic Group is identified as the biota making up the 

greatest percent cover on the hard attachment surface within the classified area. 

Biota present at lesser percent cover values within the classified area may be 

identified as Co-occurring Elements (See Section 10.6.2) or (if not a CMECS 

Biotic Group) Associated Taxa (See Section 10.3.1). 
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o Biotic Group: Mineral Boring Fauna – Areas where specialized fauna 

have bored into hard mineral substrate (rock, shell, carbonate reef, peat, 

compacted stiff clay) and constitute the dominant biological feature by 

percent cover or biomass. Several taxa (including sponges, sipunculids, 

clams, mussels, gastropods, annelids and others) have developed

mechanisms for boring into rock, shell and other mineral substrates. 

 Biotic Communities: e.g., Boring Cliona celata, Boring Penitella, 

Boring Lithophaga

o Biotic Group: Wood Boring Fauna – Anthropogenic or natural wood

substrate areas characterized or dominated by specialized fauna that have 

bored into the wood. Several taxa, including teredos or shipworms 

(bivalves), gribbles (crustaceans), and others have developed the ability 

to bore into wood so as to obtain food, protection, or both. Once woodboring fauna have begun to break the wood apart, other fauna will move 

in to occupy spaces within the wood, feeding on detritus, wood-borers, 

plankton, and other fauna.

 Biotic Communities: e.g., Boring Bankia, Boring Limnoria,

Boring Teredo

o Biotic Group: Diverse Colonizers – Areas dominated by highly varied 

and diverse communities of mixed fauna that have attached to a biotic or 

abiotic hard substrate (which may be rock, cobble, oyster reef, non-living 

coral reefs, or other substrates). Common colonizing taxa include 

anemones, tunicates, barnacles, mollusks, hydroids, bryozoans, 

gorgonians, soft or leather corals, sponges, and/or other taxa. Diverse 

Colonizers on living coral reefs are included in the Colonized Shallow 

and Mesophotic Reef Biotic Group. Diverse Colonizers can be further 

described using the Invertebrate Community Organism Size Modifiers: 

Meiofauna (dominants < 0.5 millimeter), Small Macrofauna (dominants > 

0.5 millimeter to 2 millimeters), Large Macrofauna (dominants > 2 

millimeters to 1 centimeter), Megafauna (dominants > 1 centimeter to 3 

centimeters), Large Megafauna (dominants > 3 centimeters), with all 

measurements in the smallest dimension (e.g., width or height) and not 

including the length of slender lateral projections (e.g., arms or tentacles). 

As with all biotic groups, this unit may be used when communities 

cannot be identified, as in “Diverse Colonizers (Megafauna)”, which 

provides important information despite limitations of data, e.g., video 

information.

 Biotic Communities: e.g., Anemone/Mussel/Bryozoan Colonizers 

(Large Macrofauna), Mollusk/Sponge/Tunicate Colonizers (Large 

Megafauna), Sponge/Gorgonian Colonizers
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o Biotic Group: Attached Tube-Building Fauna – Hard substrate areas 

with a percent cover dominated by tube builders, including annelids, 

phoronids, sipunculids, crustaceans, gastropods, pogonophorans, 

echiurans, priapulids, and other phyla. These animals construct chitinous, 

leathery, calcareous, sandy, mucus, or other types of tubes that are 

cemented or otherwise attached to hard substrate, and can occur in very 

high densities. If the tubes are built from a more permanent material 

(e.g., calcium carbonate) and occur in densities sufficient to construct 

substrate, these areas may be classified as Reef Biota.

 Biotic Communities: e.g., Attached Phoronids, Attached

Pogonophorans, Attached Sabellaria, Attached Serpula, Attached 

Serpulorbis

o Biotic Group: Vent/Seep Communities – Areas near deep-sea vents and 

seeps, often dominated by very large fauna (e.g., bivalves, 

pogonophorans) which derive nutrition from chemoautotrophic bacteria 

that can utilize the chemicals present in the vent or seep as an energy 

source. Many Vent/Seep Communities are spectacular ecosystems with 

very high biomass and a diversity of unusual fauna. These areas are often 

characterized by hard substrates due to the active geologic processes that 

create vents and seeps.

 Biotic Communities: e.g., Calyptogena Communities, Riftia

Communities

o Biotic Group: Attached Anemones – Hard substrate areas dominated by 

attached anemones (coelenterates which secure themselves to a hard 

substrate with a pedal disc). These assemblages are common in certain 

rocky, coastal areas.

 Biotic Communities: e.g., Attached Aiptasia, Attached Metridium

o Biotic Group: Barnacles – Areas dominated by barnacles (small filterfeeding crustaceans in a protective shell that is attached to hard substrate) 

and associated fauna (e.g., the snail, Littorina, see Figure 8.9).

 Biotic Communities: e.g., Balanus Communities, Chthamalus

Communities
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Figure 8.9. Semibalanus balanoides Communities with Co-occurring Element 

Mobile Mollusks on Hard or Mixed Substrates, Littorina littorea. 

Massachusetts. Note also the recent set of small Semibalanus. Image: G. Cicchetti.

o Biotic Group: Attached Basket Stars – Hard or mixed substrate areas 

characterized by brushy, many-armed echinoderms known as basket 

stars. Basket stars and brittle stars (see below) are both members of the 

class Ophiuroidea, but the arms of basket stars bifurcate many times to 

form a large complex that is reminiscent of a basket. Basket stars are 

usually larger than brittle stars, and maintain an upright form, generally 

clinging to hard substrate or solid objects using their bifurcated arms, 

which also function in suspension feeding.

 Biotic Communities: e.g., Attached Astrophyton, Attached

Gorgonocephalus

o Biotic Group: Attached Brachiopods – Areas dominated by 

brachiopods, a phylum of animals with two shells, a stalk-like peduncle, 

and a tentacular, ciliated feeding organ. Brachiopods resemble clams, but 

are not mollusks. In some species, the peduncle is used to attach the 

animal to hard substrate, or one of the valves is cemented to the substrate. 

In other species, the peduncle and the valves are adapted to burrowing in 

soft sediment (see Burrowing Brachiopods, below). Brachiopods may 

occur in very high densities in some areas and are common on the U.S. 

west coast. Certain species can be identified by the wide gape between 

their shells when they are feeding, but not all species exhibit this wide 

gape. Most Brachiopods feed on plankton or on detritus.

 Biotic Communities: e.g., Attached Crania, Attached Laqueous, 

Attached Terebratalia

o Biotic Group: Brittle Stars on Hard or Mixed Substrates –

Assemblages dominated by crawling, epifaunal, crevice-dwelling brittle 

stars, often living on, between, or under rocks. Brittle stars (together with 

basket stars) are Ophiuroids, a relatively mobile class of echinoderms

with long, slender arms and a distinct central disk. Some brittle star 

species are specialized for life on or among rocks and other hard 

substrates, others are specialized for infaunal burrowing, and some 
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species may be generalists, found in a variety of substrates, and utilizing 

a variety of feeding methods. 

 Biotic Communities: e.g., Amphipholis Communities,

Ophioderma Communities, Ophiothrix Communities

o Biotic Group: Attached Bryozoans – Areas dominated by abundant or 

structurally complex, attached bryozoan communities that are may be 

habitat-forming. These colonial filter-feeding animals generally have a 

protective chinitous or calcareous covering that adds structural support. 

They may occur on hard substrates as flat encrusting growths, as feathery 

branched structures, as complex calcareous shapes, as fouling 

communities, and in other forms. Certain species of bryozoans may

create extensive habitats.

 Biotic Communities: e.g., Attached Bugula, Attached 

Celleporaria, Attached Tubulipora

o Biotic Group: Chitons – Areas dominated by attached chitons, 

gastropod-like mollusks with eight calcareous dorsal plates (valves), a 

broad foot for attachment to hard substrates, and a scraping radula for 

feeding. Several species can reach high abundances on intertidal or 

subtidal rocks. Some chitons will create a depression in rock substrate for 

improved protection; however, they are classified here as Chitons, rather 

than above as Mineral Boring Fauna. 

 Biotic Communities: e.g., Attached Acanthopleura, Attached

Katharina, Attached Nutallina

o Biotic Group: Attached Corals – Subtidal (and deeper) substrates that 

are dominated by non-reef-forming corals. These include hexacorals such 

as black corals (Order Antipatheria) and gold corals (Order Zoanthidea, 

family Gerardiidae). All octocorals are non-reef forming, including soft 

corals and gorgonian sea fans and sea whips (Order Alcyonacea). Also in 

this group, bamboo corals are generally larger, erect, tree-shaped 

branching octocoral forms (with an articulated, bamboo-like skeleton) 

that are common in the deep sea. None of the octocorals produce the 

calcium carbonate structures associated with coral reefs, but octocorals 

can form important habitat areas, particularly in the deep sea, where large 

communities may cover significant area. Most species require a hard 

substrate for attachment, which may range from bedrock to a single 

pebble. Octocorals in the order Pennatulacea (sea pens, sea pansies, and 

sea feathers) are in general specialized for life on soft substrates, and are 

addressed in the Soft Sediment Fauna subclass.

 Biotic Communities: e.g., Attached Black Corals, Eugorgia

Communities, Attached Gold Corals, Attached Gorgonians, 
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Isididae Communities, Paragorgia Communities, Attached Soft 

Corals

o Biotic Group: Attached Crinoids – Assemblages on hard or mixed 

substrates that are dominated by either attached, stalked crinoids (or “sea 

lilies”) or motile (but often stationary, see Barnes 1980), comatulids (or 

“feather stars”). These animals are common in the deep sea and in other 

areas. Crinoids are a Class of echinoderm characterized (in general) by a 

stalk that supports the body, mouth, and arms of the animal. The 

branching arms are equipped with ciliated grooves that carry food items 

to the central, upward-facing mouth. 

 Biotic Communities: e.g., Attached Comanthus, Attached

Diplocrinus

o Biotic Group: Mobile Crustaceans on Hard or Mixed Substrates –

Areas where the epifaunal community is dominated by slow-moving 

crustaceans on hard or mixed substrates, often living on, between, or 

under rocks. Many of these animals feed on organic detritus, debris, or 

small fauna. This group is limited to the epifaunal crustacean taxa that are 

relatively non-motile (e.g., hermit crabs, xanthid crabs, grapsid crabs,

mysids, palaemonids and other small shrimps, amphipods, isopods) and

cannot move outside the boundaries of the classification unit within one 

day. This group does not include the larger, more mobile, usually 

predatory crustacean forms (e.g., swimming crabs, Cancer crabs, large 

spider crabs, penaied shrimps), which should be recorded as Associated 

Taxa with another Biotic Group (see Section 10.3.1) . 

 Biotic Communities: e.g., Caprellid Communities, Crangon 

Communities, Pagurus Communities

o Biotic Group: Sessile Gastropods – Hard substrate areas dominated by 

sessile (or mostly sessile) gastropods, often suspension feeders. Fauna in 

this biotic group may construct thick calcareous growths, but do not 

occur in abundance that is judged sufficient to construct substrate; where 

these species are sufficiently abundant that they do construct substrate, 

they are classified in the Reef Class as Mollusk Reef (see above).

 Biotic Communities: Attached Acmaea, Attached Crepidula, 

Attached Haliotis, Attached Vermetids

o Biotic Group: Attached Holothurians – Areas where the epifaunal 

community is dominated by sessile or slow-moving holothurians (sea 

cucumbers) on hard or mixed substrates. Holothurians living on hard 

substrate may attach firmly, or may be capable of movement over the 

substrate. Many forms are adapted to deposit feeding by moving their 

sticky tentacles over the substrate; other forms are suspension-feeders.
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 Biotic Communities: e.g., Attached Parastichopus, Attached

Psolus

o Biotic Group: Attached Hydroids – Areas dominated by mounds or mats 

of hydroids that are attached to a hard substrate. Hydroids are colonies of 

individual cylindrical polyps arranged in a branching structure, as a furry 

or brushy covering, or in other forms. Polyps are specialized for support, 

reproduction, and defense, and are armed with nematocysts (stinging 

capsules in specialized cells). Hydroids are the benthic life stage of 

planktonic jellyfish medusae, and most are predators on small life forms. 

Hydroid mounds or mats may form very dense assemblages.

 Biotic Communities: e.g., Attached Sertularia, Attached

Tubularia

o Biotic Group: Mobile Mollusks on Hard or Mixed Substrates – Areas 

dominated by slow-moving mollusks, most commonly gastropods. In 

general, the forms that reach densities sufficient to be defined as a Biotic 

Group are detritivores or suspension feeders. Slow moving predatory 

mollusks (e.g., whelks, drills, octopods) tend to be less abundant, and 

would more typically be classified in CMECS as Co-occurring Elements, 

together with another Biotic Group.

 Biotic Communities: Bittium Communities, Littorina

Communities, Urosalpinx Communities

o Biotic Group: Attached Mussels – Areas dominated by dense 

accumulations of mussels attached to a substrate other than conspecifics. 

This group includes associated faunal communities and predators on 

mussels (e.g., starfish), which may be highly conspicuous. Areas where 

mussels have constructed substrate are classified as Mussel Reef. Areas 

where mussels are not attached to a hard substrate are classified as Soft 

Sediment Fauna, Mussel Bed.

 Biotic Communities: e.g., Attached Modiolus, Attached Mytilus

o Biotic Group: Attached Oysters – Areas dominated by accumulations of 

oysters attached to a substrate other than conspecifics. Areas where 

oysters have constructed substrate are classified as Oyster Reef (see 

above). Areas where oysters are not attached to the substrate are 

classified as Soft Sediment Fauna, Oyster Bed.

 Biotic Communities: e.g., Attached Crassostrea, Attached

Ostrea

o Biotic Group: Attached Sponges – Hard or mixed substrate areas that are

dominated by sponges and their associated communities, e.g., where non-
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reef building sponge species grow attached to hard substrate or are 

nestled among hard substrate, or where reef-building sponges grow on 

hard substrates in densities that are not judged sufficient to constitute a 

reef. Most sponge species do not have fused silica spicules, and so do not 

create lasting skeletons that build reefs. Nonetheless, these more fibrous 

and ephemeral sponges provide seafloor relief and excellent habitat for 

other fauna, including many commensal species that live within the 

tissues of the sponge. 

 Biotic Communities: e.g., Attached Cliona, Attached

Halichondria, Attached Hyalonema, Attached Microciona, 

Attached Scypha

o Biotic Group: Attached Starfish – Hard or mixed substrate areas in 

which starfish (sea stars) occur in large aggregations and clearly 

dominate the biota. Practitioners should note that, in most cases, starfish 

are predators on another Biotic Group (e.g., Attached Mussels) which (as 

the forage base) would normally constitute the dominant percent cover. 

In those cases, Starfish would be described as a Co-occurring Element, 

e.g., “Biotic Group: Attached Mytilus edulis with Co-occurring Element: 

Attached Asterias rubens”. The Attached Starfish biotic group is 

intended to describe areas where starfish constitute the dominant life 

form in percent cover, not areas with occasional or scattered starfish.

 Biotic Communities: e.g., Attached Asterias, Attached Pisaster

o Biotic Group: Attached Tunicates – Areas dominated by attached 

members of the subphylum Tunicata, known as tunicates, ascidians, or 

sea squirts. Tunicates are bag-like filter feeders with an incurrent and an 

excurrent siphon. In some areas they reach high abundances. One species 

(Didemnum, see Figure 8.10) is a rapid invasive that blankets large areas, 

excludes other fauna, and has invaded many countries around the world, 

including the United States, on both the East and West coasts.

 Biotic Communities: e.g., Attached Didemnum, Attached Molgula
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Figure 8.10. Attached Tunicates, Didemnum vexillum, British Columbia.

Image: F. Poole, Search.USA.gov, USGS.

o Biotic Group: Attached Sea Urchins – Hard or mixed substrate areas 

dominated by mobile sea urchins. Many sea urchins are omnivorous, 

consuming algae, debris, sessile invertebrates, and other foods. In some 

situations, sea urchins will occur in great numbers, clearly constituting 

the dominant Biotic Group. These fauna may be associated with another 

Biotic Group (upon which they are feeding) and may be considered as 

Co-occurring Elements if the “forage” group occurs in greater percent 

cover, or dominates biomass.

 Biotic Communities: e.g., Attached Strongylocentrotus 

droebachiensis, Attached Strongylocentrotus purpurata

 Biotic Subclass: Soft Sediment Fauna – Areas that are characterized by fine 

unconsolidated substrates (sand, mud) and that are dominated in percent cover or 

in estimated biomass by infauna, sessile epifauna, mobile epifauna, mobile fauna 

that create semi-permanent burrows as homes, or by structures or evidence 

associated with these fauna (e.g., tilefish burrows, lobster burrows). These 

animals may tunnel freely within the sediment or embed themselves wholly or 

partially in the sediment. In many cases, they will regularly leave their burrows, 

and may move rapidly or swim actively after doing so, but any animal that creates 

a semi-permanent home in the sediment can be classified as Soft Sediment Fauna. 
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These animals may also move slowly over the sediment surface, but are not 

capable of moving outside of the boundaries of the classification unit within one 

day. Most of these fauna possess specialized organs for burrowing, digging, 

embedding, tube-building, anchoring, or locomotory activities in soft substrates.

Biotic communities in the Soft Sediment Fauna subclass are identified with the 

term “Bed”, to distinguish them from Attached Fauna biotic communities (which 

do not include the term “Bed”).

Within Soft Sediment Fauna, the Biotic Group is identified as the biota making up 

the greatest percent cover or the greatest estimated biomass within the classified 

area. Biota present at lesser percent cover or estimated biomass values within the 

classified area may be identified as Co-occurring Elements (See Section 10.6.2) 

or (if not a CMECS Biotic Group) as Associated Taxa (See Section 10.3.1). 

Associated Taxa include rapid epifaunal predators such as crustaceans, fishes, and 

other nekton that are capable of leaving the boundaries of the classification unit 

within one day. Associated Taxa may be capable of digging into the sediment 

surface to feed or hide (e.g., portunid crabs) but do not construct a semipermanent burrow as would define Soft Sediment Fauna. For practitioners who 

wish to better characterize Soft Sediment Fauna, the Community Successional 

Stage Modifier (Section 10.3.2, including Figure 10.1 and Table 10.3) is a helpful 

addition to classifying soft sediment communities, and can be applied to almost 

every soft-sediment area. This modifier provides ecological and functional 

information, and adds an element of assessment. 

o Biotic Group: Larger Deep-Burrowing Fauna – Assemblages 

dominated by the presence—or evidence—of larger, deep-burrowing, 

soft-bodied, generally worm-like infauna. Characteristic taxa include 

larger (body width > 2 millimeters) annelids (segmented worms), 

enteropneusts (acorn worms), sipunculids (peanut worms), priapulids 

(phallus worms), nemerteans (ribbon worms), echiuroids (spoon worms), 

and/or other worm-like fauna, typically living > 5 centimeters below the 

sediment-water interface. Diverse mixes of fauna are common, and biotic 

communities may or may not be identifiable with an abundant or 

distinctive dominant taxon. Large fecal casts, mounds, burrows, feeding 

voids, etc., may be taken as evidence of deep-burrowing fauna. However, 

areas characterized by larger, tube-building worms (that construct a 

significant tube structure rising above the sediment-water interface, but 

may live with a body position below the sediment surface) are classified 

as Larger Tube-Building Fauna. Burrowing fauna with shells (e.g., clams 

and crustaceans) are covered below in other biotic groups.

 Biotic Communities: e.g., Balanoglossus Bed, Boniella Bed, 

Glycera Bed, Nephtys Bed, Sipunculid Bed

o Biotic Group: Small Surface-Burrowing Fauna – Areas dominated by 

small, burrowing, often worm-like fauna with a body width usually < 2 
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millimeters; animals are typically found within 5 centimeters of the 

sediment-water interface. Common fauna include oligochetes, 

polychaetes, sipunculids, flatworms, nematodes, priapulids, small 

enteropneusts (acorn worms), and other phyla. Burrowing fauna other 

than worms may also be characteristic (e.g., small, surface-burrowing 

amphipods, mysids, copepods, or isopods). In many areas, surface fauna 

will be abundant, but individual animals generally associated with this 

group will be found living deeper than 5 centimeters into the sediment; 

these areas are still classified as Small Surface-Burrowing Fauna.

 Biotic Communities: e.g., Capitellid Bed, Harpacticoid Bed, 

Leptocheirus Bed, Lumbrinerid Bed, Nematode Bed, Oligochaete 

Bed, Turbellarian Bed

o Biotic Group: Diverse Soft Sediment Epifauna – Highly varied and 

diverse communities of mixed fauna that are present on the surface of 

soft unconsolidated substrates. Common taxa include annelids, 

holothurians, ophiuroids, anemones, tunicates, mollusks, sea pansies, 

hydroids, bryozoans, sea urchins, sponges, echiuroids, priapulids, and 

many others. Diverse Fine Sediment Epifauna can be further described 

using the Invertebrate Community Organism Size Modifiers: Meiofauna 

(dominants < 0.5 millimeter), Small Macrofauna (dominants > 0.5 

millimeter to 2 millimeters), Large Macrofauna (dominants > 2 

millimeters to 1 centimeter), Megafauna (dominants > 1 centimeter to 3 

centimeters), Large Megafauna (dominants > 3 centimeters), with all 

measurements in the smallest dimension (e.g., width or height) and not 

including the length of slender lateral projections (e.g., arms or tentacles). 

As with all Biotic Groups, this unit may be used when Communities 

cannot be identified, as in “Diverse Soft Sediment Epifauna (Large 

Macrofauna), which provides important information despite limitations of 

data, e.g., video information.

 Biotic Communities: e.g., Aphrodite Bed, Bryozoan/Anemone 

Bed (Megafauna), Holothurian/Ophiuroid Bed, Sand Dollar/Sea 

Pansy/Mobile Mollusk Bed (Large Megafauna) 

o Biotic Group: Larger Tube-Building Fauna – Soft sediment areas 

dominated by larger tube builders (tube width > 2 millimeters, or tube 

length > 30 millimeters), most commonly polychaetes, but including 

many other worm-like phyla (phoronids, sipunculids), crustaceans, and 

others. The tubes may be constructed in a variety of ways to produce 

calcareous, leathery, sandy, mucus-bound, chitinous, fibrous, papery, and 

other types of tubes. The animal itself may reside above or below the 

sediment surface, within the constructed tube. Some tube-building 

species (e.g., Asabellides oculata) may form extremely dense mounds of 

tubes that rise many centimeters above the seafloor. If colonization and 
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growth of these fauna and their tubes results in the construction of 

substrate that is relatively stable, these faunal structures may be classified 

as Reef Biota.

 Biotic Communities: e.g., Robust Ampelisca Bed, Asabellides

Bed, Asychis Bed, Chaetopterus Bed, Diopatra Bed, Lagis Bed, 

Loimia Bed, Phoronid Bed, Phoronopsis Bed

o Biotic Group: Small Tube-Building Fauna – Soft sediment areas 

dominated by tube-building annelids (e.g., spionids, sabellids), 

amphipods, small phoronids, or other small, surface-dwelling, tubebuilding fauna. These animals have a small tube width (< 2 millimeters), 

and the tubes often occur in dense mats. The animal itself may reside 

above or below the sediment surface within the constructed tube, which 

may be composed of a variety of materials (e.g., glued sediments, 

calcium carbonate, mucus, chitin, proteins).

 Biotic Communities: e.g., Thin Ampelisca Bed, Chone Bed, 

Paraprionospio Bed, Polydora Bed, Streblospio Bed

o Biotic Group: Tunneling Megafauna – Intertidal or Subtidal areas 

dominated by burrowing or construction activities of larger (megafaunal) 

organisms that create a water-filled tunnel with a diameter of > 1 

centimeter. Tunneling activities are often attributable to crustaceans

(generally decapods), but fishes (e.g., tilefish) and other taxa may also 

create large tunnel features. An associated mound of sediment may also 

be constructed. This biotic group is usually identified by the presence of 

tunnels or structures; the actual animal may be difficult to locate.

 Biotic Communities: e.g., Callichirus Bed, Lepidophthalmus Bed, 

Lopholatilus Bed, Neotrypaea Bed, Nephrops Bed, Squilla Bed, 

Upogebia Bed

o Biotic Group: Oligozoic Biota – Zones that are devoid of macrofauna, 

larger fauna, and microbial mats, i.e., where no evidence of larger 

multicellular life can be detected when a sufficient area of the substrate is 

sampled to deliver sub-millimeter resolution, and where microbial 

communities are not visible to the naked eye. Interstitial meiofauna, 

however, may be present or inferred. It is inappropriate to identify this 

biotic group with sampling methods that are not capable of submillimeter resolution and cannot detect infauna that may reside below the 

surface in soft sediments. Sampling methods which can resolve this biotic 

group include retrieval of substrate followed by sieving with < 0.5 

millimeter mesh size and stereoscopic examination, and sediment profile 

imaging with cameras that provide sub-millimeter resolution at the 

faceplate. This biotic group is found in areas of extremely high stress

(e.g., anoxic zones, highly toxic areas, and high-energy pebble or cobble 
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beaches) where conditions cannot support larger multicellular life. Oxic 

areas of subtidal mineral sands are generally sparsely colonized by 

multicellular organisms (e.g., haustoriid amphipods, syllids and other 

small polychaetes) and are not considered Oligozoic Biota. 

 Biotic Communities: e.g., Anoxic Oligozoic Bed, Bacterial Bed,

Meiofaunal Bed

o Biotic Group: Burrowing Anemones – Areas dominated by anemones

(solitary coelenterates) that use their pedal disc to burrow in soft 

substrates. Many species are characterized by a whorl of tentacles at the 

sediment surface; when disturbed, the animal may very rapidly retract its 

tentacles into a burrow. These anemones occur at a range of densities, 

which requires sampling gear with an appropriate resolution and 

observational footprint (e.g., video transects or plan-view still 

photographs).

 Biotic Communities: e.g., Cerianthus Bed, Edwardsia Bed

o Biotic Group: Soft Sediment Basket Stars – Sandy or muddy areas 

characterized by brushy, many-armed echinoderms known as basket 

stars. Basket stars and the more common brittle stars are members of the 

class Ophiuroidea, but the arms of basket stars bifurcate many times to 

form a large complex that is reminiscent of a basket. Basket stars are 

usually larger than brittle stars, and maintain an upright form, generally 

clinging to solid objects, conspecifics, or other fauna using their 

bifurcated arms. In some soft sediment locations, basket stars form large 

entangled aggregations consisting of many individuals and covering large 

areas. Most basket stars are suspension feeders, but some species are 

more omnivorous or predaceous.

 Biotic Communities: e.g., Asteronyx Bed, Gorgonocephalus 

arcticus Bed

o Biotic Group: Brachiopod Bed – Soft-sediment areas dominated by 

burrowing, clam-like brachiopods, a phylum of animals with two shells, a 

stalk-like peduncle, and a tentacular, ciliated feeding organ. In soft 

sediment dwelling species, the peduncle and the valves are adapted to 

burrowing. In other brachiopod species, the animal is adapted to attach to 

hard substrate (see Attached Brachiopods, above). Most brachiopods feed 

on plankton or on detritus. Brachiopods may occur in very high densities 

in some soft sediment areas, including intertidal areas (particularly on the 

west coast of the United States).

 Biotic Communities: e.g., Glottidia Bed, Lingula Bed
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o Biotic Group: Soft Sediment Brittle Stars – Fine substrate assemblages 

dominated by crawling, burrowing or infaunal brittle stars, which are a

relatively mobile class of echinoderms. Brittle stars may be either 

epifaunal or infaunal depending on the species and/or environmental 

conditions. In some situations, the central disc and several arms will be 

buried, but the remaining arm or arms will protrude typically ~ 1 

centimeter to ~ 3 centimeters into the water column, where they may be 

mistaken for worms. 

 Biotic Communities: e.g., Amphiura Bed, Ophiothrix Bed, 

Ophiura Bed

o Biotic Group: Soft Sediment Bryozoans – Areas dominated by 

bryozoans (small colonial filter-feeding animals with a calcareous 

skeleton) that may grow in complex branched structures, bushy shapes, or 

other forms. Bryozoans may be partially embedded in fine substrates, or 

may be resting, unattached, on the sediment surface.

 Biotic Communities: e.g., Bugula Bed, Celleporaria Bed, 

Schizoporella Bed

o Biotic Group: Cephalochordates – Soft-sediment areas (typically sandy) 

that are dominated by the rapidly burrowing, fish-like Amphioxus, or by 

other similar Genera of the subphylum Cephalochordata, a group of 

animals with characteristics of both vertebrates and invertebrates. These 

small (typically 2 - 15 centimeters in length) slender animals live buried 

just under the surface of sandy sediments. They feed on plankton or 

detritus that is strained from the water with a specialized feeding 

apparatus. Amphioxus and the related Genera have a worldwide 

distribution, and may occur in very high densities in some areas.

 Biotic Communities: e.g., Amphioxus Bed, Branchiostoma Bed

o Biotic Group: Clam Bed – Areas where either: (a) living clams, siphons, 

or siphon holes are the dominant surface feature, or; (b) clams dominate 

the faunal biomass. Siphons or shells may (or may not) be visible from 

above the sediment surface. The Clam Bed biotic group includes clams 

of all sizes; clam size can be specified using the Invertebrate Community 

Organism Size Modifiers: Meiofauna (dominants < 0.5 millimeter), Small 

Macrofauna (dominants > 0.5 millimeter to 2 millimeters), Large 

Macrofauna (dominants > 2 millimeters to 1 centimeter), Megafauna 

(dominants > 1 centimeter to 3 centimeters), Large Megafauna 

(dominants > 3 centimeters), with all measurements in the smallest 

dimension (e.g., the smallest shell width for most clams).
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 Biotic Communities: e.g., Arctica Bed, Donax Bed, Macoma Bed, 

Mercenaria Bed, Mulinia Bed, Mya Bed, Nucula Bed, Rangia Bed, 

Spisula Bed, Venus Bed, Yoldia Bed

o Biotic Group: Soft Sediment Crinoids – Areas dominated by crinoid 

species that are not attached to a hard substrate. Stalked crinoids or “sea 

lilies” may fix themselves to the soft seafloor or may move along the 

bottom. These animals and the motile (but often stationary, see Barnes

1980) comatulid “feather stars” are common in the deep sea and in other 

areas. They may be resting on the sediment surface, or they may be 

partially embedded in the sediment. Both groups of crinoids (sea lilies 

and feather stars) are suspension-feeding echinoderms with many 

branched arms.

 Biotic Communities: e.g., Comanthus Bed, Diplocrinus Bed, 

Rhizocrinus Bed

o Biotic Group: Mobile Crustaceans on Soft Sediments – Areas where 

the epifaunal or surface community is dominated by slow-moving 

crustaceans. This group is limited to the relatively non-motile, epifaunal,

crustacean taxa (e.g., hermit crabs, mole crabs, amphipods, mysids, 

isopods) and does not include the more mobile arthropod forms (e.g., 

swimming crabs, horseshoe crabs, penaied shrimps) which can leave the 

classified area in less than one day and are defined as Associated Taxa. 

Larger mobile crustacean forms that construct a semi-permanent home 

(lobsters, burrowing shrimps, etc.) are classified as Tunneling 

Megafauna. Small burrowing crustaceans with a body measuring < 2 mm 

in the smallest dimension are classified as Small Surface-Burrowing 

Fauna.

 Biotic Communities: e.g., Caprellid Bed, Emerita Bed, Haustoriid 

Bed, Mysid Bed, Pagurus Bed

o Biotic Group: Echiurid Bed – Soft-sediment areas dominated by 

unsegmented echiurids or “spoon worms” which are abundant on the U.S. 

west coast in both intertidal and subtidal habitats. This group also 

includes communities where U-shaped echiurid burrows constitute the 

dominant or characteristic faunal feature, even if all animals have 

retracted into their burrows and cannot be seen.

 Biotic Communities: Echiurus Bed, Listriolobus Bed, Urechis

Bed

o Biotic Group: Holothurian Bed – Soft sediment assemblages dominated 

by holothurians or “sea cucumbers”, which are common in both shallow 

and deep areas of the ocean. Holothurians common on sand or mud 

bottoms generally have features adapting them to life in soft sediment, 
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and many species feed by ingesting sediment and associated organic 

matter as they burrow through the substrate. Tracks, trails, or feces left by 

these echinoderms may also be characteristic (see Fecal Mounds, also

Tracks and Trails in the Inferred Fauna section below). The Holothurian 

Bed group is used only when the holothurians are present; use the Tracks 

and Trails or Fecal Mounds Biotic Groups when there is evidence of their 

presence, but living individuals are not seen. 

 Biotic Communities: e.g., Caudina Bed, Kolga Bed, Leptosynapta

Bed, Stichopus Bed

o Biotic Group: Hydroid Bed – Areas dominated by hydroid species that 

are not attached to a hard substrate. These animals may be resting on the 

sediment surface or may be partially embedded in the sediment. Hydroids 

are the benthic life stage of planktonic jellyfish medusae, and most are 

predators on small life forms. Hydroids are colonies of individual polyps 

usually arranged in a branching or bushy pattern. The polyps are 

specialized for various roles, and defensive/prey capture polyps are 

armed with nematocysts (stinging capsules in specialized cells). Hydroids 

may form large mounds or mats in some soft sediment areas. 

 Biotic Communities: Sertularia Bed, Tubularia Bed

o Biotic Group: Mobile Mollusks on Soft Sediments – Areas dominated 

by epifaunal, slow-moving, generally detritivorous, herbivorous, or 

omnivorous gastropods, scaphopods, or other mollusks foraging at the 

surface of unconsolidated sediments. These animals may be partly buried

in the substrate. Predatory mobile mollusks such as moon snails, 

octopods, or whelks are generally preying on another Biotic Group (e.g., 

Clam Bed) which (as the forage base) would normally constitute the 

dominant percent cover. In those cases, Mobile Mollusks would be 

described as a Co-occurring Element, e.g., “Biotic Group: Spisula Bed 

with Co-occurring Element: Polinices Bed”.

 Biotic Communities: e.g., Nassariid Bed, Olivella Bed, Polinices 

Bed, Scaphopod Bed, Turritellid Bed

o Biotic Group: Mussel Bed – Soft-sediment areas dominated by mussel 

species that are not attached to a hard substrate. These animals may be 

resting on the sediment surface, partially embedded in the sediment, or

attached to conspecifics (by using their byssal threads), or to a piece of 

gravel, e.g., in Slightly Gravelly Fine Sediments. Individuals in the 

Mussel Bed Group are not present in densities sufficient to construct 

substrate; in that case, they would be classified as Mussel Reef.

 Biotic Communities: e.g., Modiolus Bed, Mytilus Bed
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o Biotic Group: Oyster Bed – Soft-sediment areas dominated by oyster 

species that are not attached to a hard substrate and are not present in 

densities sufficient to construct substrate. These animals may be resting 

on the sediment surface, partially embedded in the sediment, or attached 

to conspecifics.

 Biotic Communities: e.g., Crassostrea Bed, Ostrea Bed

o Biotic Group: Pennatulid Bed – Subtidal soft-bottom habitats that are 

dominated by sea pens or sea pansies (Phylum Cnidaria, Order 

Pennatulacea). These are colonial octocorals with a central stem-like 

support attached to a root-like peduncle, adapted for life in soft 

sediments. An arrangement of suspension-feeding polyps in a single 

plane on two sides of the central stem (which is a specialized polyp) 

gives some sea pens the overall appearance of a feather or quill pen. The 

root-like peduncle is embedded in soft sediments, but the sea pen can 

move to a new area if conditions are unfavorable. Sea pansies are more 

compact and fleshier than sea pens. Pennatulids are often common in 

deeper waters. 

 Biotic Communities: e.g., Halipteris Bed, Pennatula Bed, Renilla

Bed, Stylatula Bed

Figure 8.11. Sea Pen Bed, Stylatula elongata, San Diego, California.

Image: G. Cicchetti.

o Biotic Group: Sand Dollar Bed – Assemblages dominated by surfacedwelling, “irregular” echinoids of the Phylum Echinodermata and Order 

Clypeasteroida (e.g., sand dollars, sea biscuits). Sand dollars typically 

move on top of the sediment surface or burrow in the top few centimeters 

of sediment. Sand dollars are characterized by a flat body and short 
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spines, to visually distinguish them from Burrowing Urchins and Soft 

Sediment Sea Urchins (see biotic groups below). Most sand dollars are 

deposit feeders; some are suspension feeders.

 Biotic Communities: e.g., Clypeaster Bed, Dendaster elongatus 

Bed, Mellita Bed

o Biotic Group: Scallop Bed – Areas dominated by accumulations of 

scallops. Scallops have a series of small eyes and are mobile, clapping 

their shells together and pulsing through the water to escape predators 

such as starfish. Scallops may occur in high densities, but populations can

be significantly affected by a number of factors, including larval 

recruitment, predation, and fishing pressure.

 Biotic Communities: e.g., Argopecten Bed, Placopecten Bed

o Biotic Group: Sponge Bed – Sandy or muddy areas of the seafloor that 

are dominated by sponges and their associated communities, but do not 

create substrate such that they would be considered Reef Biota.

Hexactinellid “glass sponges” that are capable of forming reefs may be 

classified as a Sponge Bed when occurring on sand or mud in densities 

not deemed adequate to compose a reef. Many sponge species have 

developed holdfast organs that adapt them to life in soft sediments, and 

can provide excellent structural habitat for other creatures, including the 

many commensal organisms that typically inhabit the tissues of living 

sponges.

 Biotic Communities: e.g., Monoraphis Bed, Tetilla mutabilis Bed

o Biotic Group: Starfish Bed – Soft sediment areas in which starfish occur 

in large aggregations and clearly dominate the biota. Practitioners should 

note that, in most cases, starfish are predators on another Biotic Group 

(e.g., Clam Bed) which (as the forage base) would normally constitute the 

dominant percent cover or biomass. In those cases, Starfish would be 

described as a Co-occurring Element, e.g., “Biotic Group: Clam Bed with 

Co-occurring Element: Astropecten”.

 Biotic Communities: e.g., Asterias Bed, Astropecten Bed

o Biotic Group: Tunicate Bed – Sandy or muddy areas dominated by 

members of the subphylum Urochordata, including ascidians, sea squirts, 

and other tunicates. Tunicates are bag-like organisms that use incurrent 

and excurrent siphons for filter feeding and respiration. These animals 

may be resting on the sediment surface, partially embedded in the 

sediment, or attached to conspecifics. On both East and West coasts of 

the U.S., and in many other areas worldwide, colonies of the invasive sea 

squirt Didemnum are rapidly invading and smothering local biotopes.
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 Biotic Communities: e.g., Ciona Bed, Didemnum Bed 

o Biotic Group: Burrowing Urchins – Assemblages dominated by 

burrowing, “irregular” echinoids (e.g., burrowing urchins, heart urchins). 

These flattened urchins typically live underneath the sediment surface

and feed on mud or on particles of detritus. 

 Biotic Communities: e.g., Echinocardium Bed, Lovenia 

cordiformis Bed

o Biotic Group: Sea Urchin Bed – Sandy or muddy areas dominated by 

“regular” echinoids (e.g., sea urchins). These rounded urchins typically 

live on top of the sediment surface, and several species are well adapted 

to life on soft sediments, occurring in great numbers in certain locations.

 Biotic Communities: e.g., Lytechinus anamesus Bed, Lytechinus 

pictus Bed

 Biotic Subclass: Inferred Fauna – Areas dominated by evidence (real or 

inferred) of faunal activity, but where the fauna themselves are not currently 

present or evident, given the sampling methodology.

o Biotic Group: Egg Masses – Areas distinguished by egg masses, egg 

cases, or other lasting evidence of gametes or reproduction. Many 

burrowing or tube-dwelling polychaetes will produce egg masses that 

look like bags of mucus attached to the soft sediment seafloor. 

Gastropods also often produce distinctive egg cases.

 Biotic Communities: e.g., Busycon Egg Cases, Polychaete Mucus 

Cases, Polynices Egg Collars, Squid Egg Masses

o Biotic Group: Fecal Mounds – Areas distinguished by large fecal 

mounds or castings. These features are characteristic of larger depositfeeding polychaetes and other mud-ingesting fauna. Mounds or castings 

are not always present even when these fauna are abundant, particularly 

when water movements (currents, waves) are sufficient to remove the 

deposits.

 Biotic Communities: e.g., Arenicola Castings, Balanoglossid 

castings, Holothurian Castings

o Biotic Group: Pelletized, Fluid Surface Layer – Areas distinguished by 

a fluid, fecal-rich, pelletized surface layer, which is typically 5 - 15 

millimeters thick (Rhoads and Young 1970). This layer is characteristic 

of deposit-feeding polychaetes, deposit-feeding clams, and/or other 

fauna. This layer is indicative of deposit feeders, but is not always present 
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in deposit feeding communities, particularly when currents are sufficient 

to remove the layer.

 Biotic Communities: e.g., Fluidized Capitellid Layer, Fluidized

Deposit Feeder Layer, Fluidized Maldanid Layer, Fluidized Yoldia

Layer

o Biotic Group: Tracks and Trails – Areas where sediment surface 

patterns are dominated by tracks and trails left by locomotion of mobile 

epifauna (e.g., snails, holothurians, crustaceans), and other fauna that are 

no longer present. These are common in deeper waters, and in other areas 

where sediments are less disturbed by physical energy. The appropriate 

invertebrate size modifier (e.g., Megafaunal, Macrofaunal) may be used 

to describe the sizes of the organisms suspected of leaving the marks 

being evaluated.

 Biotic Communities: e.g., Decapod Tracks, Gastropod Trails, 

Holothurian Trails

Biotic Class: Microbial Communities

Areas dominated by colonies of microscopic or single-celled organisms that form a hard 

structure, visible film, layer, or mat on or near the surface of the substrate. Colonies may 

be composed of benthic microalgae (e.g., diatoms), photosynthetic bacteria (e.g., 

cyanobacteria), archaea, saprotrophic bacteria (e.g., decomposers or decay organisms), 

chemoautotrophic bacteria, or other microbial groups. These features may exist on or 

near the surface of the sediment either subtidally or subaerially (Figure 8.12), or they may 

exist as extensive areas of decay associated with dead organisms that have fallen to the 

seafloor (Figure 8.13). 

Note: There may be high levels of biotic diversity within microbial mats. Microbial mats 

are often encountered in extreme environments where grazing pressure from multicellular organisms is reduced; for example, they can be observed in the high intertidal 

zone, in areas of low dissolved oxygen, and in deep-sea areas around thermal vents.

 Biotic Subclass: Structure Forming Microbes – Areas dominated by microbes 

that form a hard structure, generally through secretions and entrapment of 

minerals and sediments.

o Biotic Group: Xenophyophores – Areas (typically found in hadal zones 

and on the abyssal plains) dominated by tests of large, living, benthic 

foraminifera (“forams”), most of which are epifaunal, moving very 

slowly over the seabed. The tests of these single-celled organisms may be 

surprisingly large, several or many centimeters in size. The multinucleated single cell lives in the interlaced fine tubules that constitute the 

structure of the test. The tests are made of secretions, scavenged minerals, 

and small particles around the tubules, and may take many shapes -
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rounded, globular, densely branching, or stick-like (protruding vertically 

from the sediment, with a portion that is buried). Evidence suggests that 

Xenophyophores exist in high densities over large areas of the abyssal 

and hadal seafloor. 

 Biotic Communities: e.g., Occultammina Communities, 

Syringammina Communities

o Biotic Group: Stromatolites – Areas dominated by large, mound-like 

formations built up in shallow marine areas by secretions of 

cyanobacteria, which further entrap minerals and sediment. They form 

Earth’s oldest fossils and originated over 3 billion years ago.

 Biotic Communities: e.g., Stromatolite Mound Communities

 Biotic Subclass: Mat/Film Forming Microbes – Areas dominated by microbes 

that form soft structures, generally through accumulations of conspecifics and 

other microbes into a matrix that appears as strands, a thin film, or a thicker mat.

o Biotic Group: Microphytobenthos – Areas dominated by a visible 

accumulation of benthic diatoms, cyanobacteria, unicellular algae, and 

other single-celled organisms. These may appear at the surface of the 

substrate in the form of either (a) a thin film or stain or (b) a thicker crust 

or “felt.” These forms may occur on rock or unconsolidated substrates in 

subtidal, intertidal, or supratidal areas.

 Biotic Communities: e.g., Diatom Felt, Microbial Stain

o Biotic Group: Bacterial Mat/Film – Areas dominated by colonies of 

bacterial decomposers and other decay organisms. These colonies can 

range in appearance from delicate and filamentous to a dense mass that 

may blanket the sediment surface. See Figure 8.12 for an example of a 

bacterial mat.

 Biotic Communities: e.g., Beggiatoa Communities

o Biotic Group: Bacterial Decay – Areas dominated by colonies of 

bacterial decomposers and other decay organisms that are observed

covering and rotting larger organic matter (such as macroalgal debris, 

fish kills, or similar large organic inputs). See Figure 8.13 for an example 

of bacterial decay.

 Biotic Communities: e.g., Beggiatoa Communities on Decaying 

Materials 
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Figure 8.12. Bacterial Mat: Tidal Flat in Humboldt Bay, California.

Image: Annie Eicher US Fish and Wildlife Service.

o Biotic Group: Vent Microbes – Areas dominated by chemoautotrophic 

bacteria living on or near hydrothermal vents. These bacteria can use the 

chemicals present around the vent as an energy source. The bacteria are 

present in the water column and on substrate near vents as bacterial mats, 

films, and strands. They form the primary food source (as symbionts or as 

free-living bacterial clusters) for the gigantic and diverse fauna that inhabit 

Vent Communities. Vent Microbes colonize new vents, making the area 

hospitable to other fauna.

 Biotic Communities: e.g., Thiobacillus Communities, 

Thermoacidophiles Communities.

Biotic Class: Moss and Lichen Communities

Tidal areas dominated by submerged or emergent mosses or lichens. Communities 

dominated by mosses are limited to freshwater situations. Although some mosses have 

been reported in tidal salt marshes, they have not been reported as dominant (Garbary et 

al. 2008). Lichens, on the other hand, occur in both freshwater and marine environments 

in relatively recognizable zones based on, among other factors, the extent to which they 

are submerged or flooded (Hawksworth 2000; Fletcher 1973; Gilbert and Giavarini 

1997). Lichens are generally recognized as a symbiotic association with a fungus and an 

alga (or cyanobacterium) living together and forming patches or a visible pattern on the 

surface of the substrate.
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Figure 8.13. Bacterial Decay: White Clusters of Decay Bacteria on Dead 

Macroalgae in Narragansett Bay, Rhode Island.

Photograph is a sediment profile image, showing a cross-sectional slice into the substrate 

and the overlying water column. Image: G. Cicchetti.

 Biotic Subclass: Freshwater Tidal Lichens – Freshwater tidal areas dominated 

by salt-intolerant lichen species that form patches or visible patterns on the 

surface of the substrate. Freshwater lichen Biotic Groups are based on a 

modification of Gilbert and Giavarini (1997).

o Biotic Group: Freshwater Submerged and Regularly Flooded Tidal 

Lichen Zone – Submerged or regularly flooded freshwater tidal areas 

dominated by lichens that can tolerate regular inundation. This zone 

includes the Submerged Zone described by Gilbert and Giavarini.

 Biotic Communities: To be determined.

o Biotic Group: Freshwater Irregularly Flooded Tidal Lichen Zone –

Tidal areas that are irregularly flooded (less often than daily) by tidal or 

non-tidal floods. Areas are generally characterized by lichen species that 

require moist or damp substrates. This zone corresponds to the Fluvial 

Mesic and Fluvial Xeric Zones described by Gilbert and Giavarini, but 
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the CMECS group only includes the parts related to the Tidal Lichen 

Zones.

 Biotic Communities: To be determined.

 Biotic Subclass: Marine Lichens – Marine tidal areas dominated by lichen 

species that form patches or visible patterns on the surface of the substrate. 

Marine Lichen Biotic Groups are based on a modification of Fletcher (1973).

o Biotic Group: Marine Intertidal Lichen Zone – Zones dominated by 

patches of lichens that are regularly submerged by marine tides. This 

zone corresponds to the Littoral Zone described by Fletcher.

 Biotic Communities: e.g., Cocotrema Communities, Lecanora

Communities, Intertidal Verrucaria Communities

o Biotic Group: Marine Supratidal Lichen Zone – Zones dominated by 

patches of lichens in association with the supratidal zone (splash zone). 

These areas are rarely submerged, but are regularly wetted by splash and 

sea spray. These lichen zones are most often associated with rocky shores 

with abundant sea spray. This zone corresponds to the Supralittoral Zone 

described by Fletcher.

 Biotic Communities: e.g., Anaptychia Communities, Caloplaca

Communities, Ramalina Communities, Xanthoria Communities, 

Supratidal Verrucaria Communities

 Biotic Subclass: Freshwater Tidal Moss – Freshwater tidal areas dominated by 

moss species.

o Biotic Group: Submerged Freshwater Tidal Moss – Freshwater tidal 

areas dominated by submerged or regularly flooded moss species.

 Biotic Communities: e.g., Fontinalis antipyretica Nonvascular 

Vegetation

o Biotic Group: Emergent Freshwater Tidal Moss – Emergent freshwater 

tidal marshes dominated by mosses.

 Biotic Communities: To be determined.

Biotic Class: Aquatic Vegetation Bed

This class includes subtidal or intertidal bottoms and any other areas characterized by a 

dominant cover of rooted vascular plants, attached macroalgae, or mosses, which are 

usually submersed in the water column or floating on the surface. They may be exposed 

during low tides. Non-rooted floating vegetation and free floating macroalgae are 
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included with the Planktonic Biota Biotic Setting under the Floating/Suspended Plants 

and Macroalgae Subclass.

 Biotic Subclass: Benthic Macroalgae – Aquatic beds dominated by macroalgae

attached to the substrate, such as kelp (Figure 8.14), intertidal fucoids, and 

calcareous algae. Macroalgal communities can exist at all depths within the photic 

zone, on diverse substrates, and across a range of energy and water chemistry 

regimes. In the CMECS framework, macroalgae that dominate the benthic 

environment and form a vegetated cover fall within this subclass. Macroalgal 

communities (typically coralline/crustose algae) that build substrate in a reef 

setting are categorized in the BC Reef Biota Class instead.

Many macroalgal types and communities have low temporal persistence and can 

bloom and die-back within short periods. This aspect of macroalgae is reflected 

with the temporal persistence modifier, which allows further description of the 

units in this subclass.

While many researchers organize macroalgae based on their pigmentation, 

CMECS takes a growth morphology approach to defining benthic algal biotic 

groups. This decision was driven by the fact that macroalgal assemblages often 

include a variety of co-existing algal species, making delineations of individual

species difficult. This approach also captures the influence that the algal growth 

structure has in shaping the local environment—by providing shelter, shade, and 

detrital material to an area, which is important to associated fauna. 

The Biotic Group level of classification here is a modification of the “Littler 

functional-form model” for marine macroalgae, as described by Littler, Littler, 

and Taylor (1983) and promoted by Lobban and Harrison (1997). The Littler 

functional form groups are the sheet group, filamentous group, coarsely branched 

group, thick leathery group, jointed calcareous group, and crustose group. Littler, 

Littler, and Taylor (1983) discuss the morphological, metabolic, and ecological 

significance of each group, and they point out that these groups are best 

considered as recognizable points along a continuum (rather than as discrete bins). 

Biotic Groups and Communities defined by macroalgae generally also include a 

diversity of associated fauna, including many that consume macroalgae (e.g., sea 

urchins and mollusks); these may be characterized as Modifiers: Associated Taxa, 

or Co-occurring Elements.

o Biotic Group: Calcareous Algal Bed – Areas dominated by calcareous 

algae that incorporate calcium carbonate into their tissues, support their 

own weight, and have an upright growth form. Calcareous algae can form 

carpets on the bottom, and—as they decay—the calcareous skeletons

remain behind, occasionally forming loose accumulations on the bottom 

resembling chips. Calcareous algae that occur in a reef setting are 

included in the Colonized Shallow/ Mesophotic Reef biotic group.
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 Biotic Communities: e.g., Corallina Communities, Halimeda 

Communities, Jania Communities, Penicillus Communities

Figure 8.14. Macroalgae: Canopy Forming Algae, Coastal California.

o Biotic Group: Canopy-Forming Algal Bed – Areas dominated by 

canopy-forming algae that have complex growth forms with holdfasts 

and well-defined stipes and blades. Canopy forming algae are 

distinguished from other types of macroalgae, in that they often reach 

heights of several meters or greater. Their presence alters water energy 

patterns and provides shelter for other marine organisms. Kelp beds are 

an example of canopy forming algal communities (Figure 8.14).

 Biotic Communities: e.g., Alaria Communities, Laminaria 

Communities, Macrocystis Communities, Mixed Kelp 

Communities, Nereocystis Communities

o Biotic Group: Coralline/Crustose Algal Bed – Areas dominated by 

coralline or crustose algae that incorporate calcium carbonate into their 

tissues and form crusts on the substrate in many marine environments. 

Coralline algae can be attached or unattached (as in the rhodoliths that

form nodules, which can occur in loose accumulations on the substrate). 

In the attached algae, the thalli are fixed to the substrate. 

Coralline/Crustose algae that occur in a reef setting are included in the 

Colonized Shallow /Mesophotic Reef biotic group.
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 Biotic Communities: e.g., Hildenbrandia Communities, 

Lithothamnion Communities, Lithophyllum Communities, 

Peyssonnelia Communities, Porolithon Communities,

Phymatolithon Communities

o Biotic Group: Filamentous Algal Bed – Areas dominated by filamentous 

algae that have a growth form consisting of fine filaments or strands with 

no blades or stipes. Filaments may branch, but they lack complex 

structures. The strands are undifferentiated (with a growth axis in one 

direction). Filamentous algae can form dense mats.

 Biotic Communities: e.g., Filamentous Aghardiella Communities, 

Chaetomorpha Communities, Chordaria flagelliformis 

Communities, Cladophora sericea Communities

o Biotic Group: Leathery/Leafy Algal Bed – Areas dominated by 

leathery/leafy algae have a variety of specialized tissues (including thalli)

that resemble stems and leaf-like blades. They generally maintain their 

shape when removed from water, and they often possess air bladders 

(pneumatocysts) and other flotation bodies.

 Biotic Communities: e.g., Ascophyllum Communities, Caulerpa 

Communities, Chondrus Communities, Codium Communities, 

Fucus distichus Communities, Palmaria Communities

o Biotic Group: Mesh/Bubble Algal Bed – Areas dominated by mesh or 

bubble algae that form small, generally spherical masses attached to the 

benthos. They may develop lobes as they grow, but they do not further 

differentiate at the macro level. These masses may be hard or leathery, 

and they can sometimes be hollow. Bubble algae can be fast growing,

quickly colonizing exposed reef surfaces, overtaking new coral growth,

and deterring other animals from attaching there.

 Biotic Communities: e.g., Dictyosphaeria Communities, Valonia 

Communities, Ventricaria Communities

o Biotic Group: Sheet Algal Bed – Areas dominated by sheet (thallose) 

algae that form thin, undifferentiated, membranous sheets with no stipe or 

blades. Growth in these algae occurs in two directions. The sheets can be 

as thin as a single cell.

 Biotic Communities: e.g., Agardhiella Sheet Algae

Communities, Grinnella americana Communities, Monostroma 

grevillei Communities, Ulva lactuca Communities

o Biotic Group: Turf Algal Bed – Areas dominated by turf algae that 

represent a multi-specific assemblage of diminutive, often filamentous, 
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algae that attain a canopy height of only 1 - 10 millimeters (see Steneck 

1988 for review). These microalgal species have a high diversity (more 

than 100 species in the western Atlantic), although only 30 - 50 species 

commonly occur at one time. There is a high turnover of individual turf 

algal species seasonally; only a few species are able to persist or remain 

abundant throughout the year. But turf algae—when observed as a 

functional group—remain relatively stable year round (Steneck and 

Dethier 1994), and they are often able to recover rapidly after being 

partially consumed by herbivores. Turfs are capable of trapping ambient 

sediment, and they kill corals by gradual encroachment.

 Biotic Communities: e.g., Mixed Algal Turf Communities

 Biotic Subclass: Aquatic Vascular Vegetation – Aquatic vascular vegetation 

beds dominated by submerged, rooted, vascular species (such as seagrasses, 

Figure 8.15) or submerged or rooted floating freshwater tidal vascular vegetation 

(such as hornworts [Ceratophyllum spp.] or naiads [Najas spp.]).

Note: Nomenclatural standards and punctuation for vegetated biotic communities 

are taken directly from FGDC-STD-005-2008. Strata are separated by a “/” (i.e.,

tree/shrub/herbaceous). Hyphens between species names indicate that they are in 

the same strata. Parentheses indicate that the species is important in defining the 

association, but may not be in every observation of the association. The name of 

the FGDC-STD-005-2008 Class is always used at the end of the association 

name. The epithet, “[Provisional]” is used when the type has been identified, but 

not yet formally incorporated into FGDC-STD-005-2008. 

o Biotic Group: Freshwater and Brackish Tidal Aquatic Vegetation –

Tidal aquatic vegetation beds dominated by submerged, rooted, vascular 

species that have limited (or no) salt tolerance. Some species, such as 

Ruppia maritima, can have a wide range of salt tolerance, and are 

included in this group when occurring in low salt environments or with 

other salt intolerant species that indicate low salt environments. 

 Biotic Communities: e.g., Ceratophyllum demersum – Vallisneria 

americana – Najas spp. Tidal Herbaceous Vegetation, Ruppia 

maritima - Stuckenia pectinata Herbaceous Vegetation

o Biotic Group: Seagrass Bed – Tidal aquatic vegetation beds dominated 

by any number of seagrass or eelgrass species, including Cymocedea sp., 

Halodule sp., Thalassia sp., Halophilla sp., Vallisnera sp., Ruppia sp., 

Phyllospadix sp., and Zostera sp.. Seagrass beds (Figure 8.15) may occur 

in true marine salinities, and they may extend into the lower salinity 

zones of estuaries.

Seagrass beds are complex structural habitats that provide refuge and 

foraging opportunities for abundant and diverse faunal communities in 
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shallow waters. Seagrass beds require a specific set of ecological 

conditions for success, and they are generally perceived as areas of high 

environmental quality.

The list of biotic communities for this group is long: a few examples are 

provided below, and the complete list is available in Appendix F.

 Biotic Communities: e.g., Syringodium filiformis – (Thalassia 

testudinum) Herbaceous Vegetation, Halophila engelmannii

Herbaceous Vegetation, Zostera marina Herbaceous Vegetation

Figure 8.15. Seagrass Bed: Florida Keys National Marine Sanctuary.

Biotic Class: Emergent Wetland

Areas in this class are characterized by erect, rooted, herbaceous hydrophytes—excluding 

emergent mosses and lichens. This vegetation is present for most of the growing season 

in most years. These wetlands are usually dominated by perennial plants. This CMECS 

class is equivalent to the Emergent Wetland Class from FGDC-STD-004 (FGDC 1996b).

 Biotic Subclass: Emergent Tidal Marsh – Communities dominated by 

emergent, halophytic, herbaceous vegetation (with occasional woody forbs or 

shrubs) along low-wave-energy, intertidal areas of estuaries and rivers.

Biotic communities in this subclass are equivalent to National Vegetation 

Classification Associations of FGDC-STD-005-2008, and follow their naming 

conventions (FGDC 2008). However, FGDC-STD-005-2008 does not split 
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marshes into “herbaceous” or “scrub-shrub” at their Group level. As a result, 

some of the names of FGDC-STD-005-2008 types (which correspond to the 

CMECS Emergent Wetland class) indicate that the biotic community is a “Dwarfshrubland.” These specific communities are dominated by woody forbs, which—

while technically dwarf-shrubs—function more like herbaceous vegetation. These 

types were included in Emergent Tidal Marsh, because their total floristics and 

physiognomy indicate an herbaceous marsh setting.

Vegetation in this subclass is composed of emergent aquatic macrophytes, 

especially halophytic species—chiefly graminoids (such as rushes, reeds, grasses 

and sedges), shrubs, and other herbaceous species (such as broad-leaved emergent 

macrophytes, rooted floating-leaved and submergent species [aquatic vegetation], 

and macroscopic algae). The vegetation is usually arranged in distinct zones of 

parallel patterns, which occur in response to gradients of tidal flooding frequency 

and duration, water chemistry, or other disturbances.

Tides may expose mudflats that contain a sparse mix of pioneering forb and 

graminoid species. Salinity levels (which control many aspects of salt-marsh 

chemistry) vary depending on a complexity of factors, including frequency of 

inundation, rainfall, soil texture, freshwater influence, fossil salt deposits, and 

more. Salt marshes often grade into (or are intermixed with) scrub-shrub wetlands 

in higher areas. See Figure 8.16 for an example of an emergent tidal marsh.

Figure 8.16. Emergent Tidal Marsh near Wilmington, North Carolina.

(Photo by Nancy Carter – www.nancycarterartist.com).
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o Biotic Group: Brackish Marsh – Marshes dominated by species with a 

wide range of salinity tolerance. Depending on the salinity levels (0.5–

30), more or less salt-intolerant species may be present. The list of biotic 

communities for this group is long: a few examples are provided below, 

and the complete list is available in Appendix F.

 Biotic Communities: e.g., Amaranthus cannabinus Tidal 

Herbaceous Vegetation, Calamagrostis nutkaensis – Argentina 

egedii – Juncus balticus Herbaceous Vegetation

o Biotic Group: Freshwater Tidal Marsh – Tidally influenced riverine 

marshes with salinity levels less than 0.5, which are dominated by salt–

intolerant, herbaceous species (e.g., Juncus sp., Eleocharis sp., and 

Zizania sp.). Non-tidal, palustrine, freshwater marshes are beyond the

scope of CMECS. The list of Biotic Communities for this group is long: a 

few examples are provided below, and the complete list is available in

Appendix F.

 Biotic Communities: e.g., Deschampsia caespitosa – Horkelia 

marinensis Herbaceous Vegetation, Eleocharis fallax – Eleocharis 

rostellata – Schoenoplectus americanus – Sagittaria lancifolia

Herbaceous Vegetation

o Biotic Group: High Salt Marsh – Salt marshes dominated by 

herbaceous, emergent vegetation and forb-like dwarf shrubs; areas are 

infrequently flooded by tides and characterized by distinctive patterns of 

halophytic vegetation (e.g., Spartina patens). Low shrubs may be present,

but they are not dominant. Shrub-dominated portions of salt marshes are 

included in the Saltwater Tidal Scrub-Shrub Wetland Biotic Group. The 

list of biotic communities for this group is long: a few examples are 

provided below, and the complete list is available in Appendix F.

 Biotic Communities: e.g., Spartina patens – Festuca rubra –

(Spartina pectinata) Herbaceous Vegetation, Juncus roemerianus

Herbaceous Vegetation

o Biotic Group: Low and Intermediate Salt Marsh – Salt marshes that 

are regularly flooded by tides so as to support characteristic halophytic 

vegetation (e.g., Spartina alterniflora). In locations with appropriate 

topography and tidal exchange, extensive meadows may form. Shrubs are 

less common in these areas. The list of biotic communities for this group 

is long: a few examples are provided below, and the complete list is 

available in Appendix F.

 Biotic Communities: e.g., Deschampsia caespitosa – (Carex 

lyngbyei, Distichlis spicata) Herbaceous Vegetation, Salicornia 
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virginica - Distichlis spicata - Triglochin maritima - (Jaumea 

carnosa) Herbaceous Vegetation

 Biotic Subclass: Vegetated Tidal Flats – Tidal Flats or Pannes (see GC for 

definition) colonized by herbaceous vegetation, usually with sparse cover. Cover 

is not sufficiently dense or raised to constitute a marsh.

o Biotic Group: Vegetated Freshwater Tidal Mudflat – Tidal mudflats in 

freshwater riverine systems colonized by sparse, emergent, salt-intolerant 

vegetation.

 Biotic Communities: To be determined.

o Biotic Group: Vegetated Salt Flat and Panne – Tidal Salt Flats or 

Pannes (see GC for definition) colonized by sparse, emergent, halophytic,

herbaceous or woody forb vegetation. The list of biotic communities for 

this group is long: a few examples are provided below, and the complete 

list is available in Appendix F.

 Biotic Communities: e.g., Sporobolus virginicus – Distichlis 

spicata Herbaceous Vegetation, Salicornia (virginica, bigelovii, 

maritima) – Spartina alterniflora Herbaceous Vegetation

Biotic Class: Scrub-Shrub Wetland

Emergent wetland areas dominated by woody vegetation that is generally less than 6 

meters tall. Characteristic species include true shrubs, young trees, and trees or shrubs 

that are small or stunted due to environmental conditions. Scrub-Shrub Wetland includes 

the shrub-dominated portions of high salt marshes—as well as stunted or low mangrove 

communities. This CMECS Class is equivalent to the Scrub-Shrub Wetland Class of 

FGDC-STD-004; however, the palustrine and non-tidal riverine portions of FGDC-STD004 class are beyond the scope of CMECS.

 Biotic Subclass: Tidal Scrub-Shrub Wetland – Estuarine or tidal riverine areas 

dominated by shrub vegetation that has less than 10% tree cover. (The cutoff 

value is the standard employed by FGDC-STD-005-2008 for defining the 

Shrubland and Grassland Formation Class [FGDC 2008]).

o Biotic Group: Brackish Tidal Scrub-Shrub – Tidal areas dominated by 

shrub or immature tree species that are less than 6 meters tall and have a 

range of salt tolerance. Salinity may range from 0.5–30 (PSS).

 Biotic Communities: e.g., Lonicera involucrata / Argentina egedii

Tidal Shrubland [Provisional]

o Biotic Group: Freshwater Tidal Scrub-Shrub – Tidal areas dominated

by shrub or immature tree species that are less than 6 meters tall and are 

salt intolerant. Salinity levels are less than 0.5. The list of biotic 
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communities for this group is long: a few examples are provided below, 

and the complete list is available in Appendix F.

 Biotic Communities: e.g., Alnus (incana ssp. rugosa, serrulata) –

Cornus amomum Shrubland, Morella cerifera – Toxicodendron 

radicans / Spartina bakeri Shrubland

o Biotic Group: Saltwater Tidal Scrub-Shrub – Tidal areas dominated by 

halophytic shrubs or immature trees that are less than 6 meters tall. 

Vegetation is composed of halophytic species, chiefly shrubs and other 

herbaceous species. The vegetation is usually arranged in distinct zones 

of parallel patterns in response to gradients of tidal flooding frequency 

and duration, water chemistry, or other disturbances. The list of Biotic 

Communities for this group is long: a few examples are provided below, 

and the complete list is available in Appendix F.

 Biotic Communities: e.g., Borrichia frutescens / Spartina 

spartinae Shrubland, Baccharis halimifolia – Iva frutescens –

Morella cerifera – (Ilex vomitoria) Shrubland

Biotic Group: Tidal Mangrove Shrubland – Tidally influenced, dense, 

tropical or subtropical areas dominated by dwarf or short mangroves (and 

associates) that are generally less than 6 meters in height. Commonly 

found on intertidal mud flats along the shores of estuaries. Tidal mangrove 

shrublands may include immature stands or stunted mature trees that 

indicate a harsh growing environment. Areas characterized by tall 

mangroves (> 6 meters) are placed in the Tidal Mangrove Forest Biotic 

Group. 

Where tidal amplitude is relatively low, the vegetation forms narrow 

bands along the coastal plains, and it rarely penetrates inland more than 

several kilometers along rivers. Where tidal amplitude is greater, 

mangroves extend further inland along river courses, forming extensive 

stands in the major river deltas. Also, mangrove cays may occur within the 

lagoon complex of barrier reefs.

The list of biotic communities for this group is long: a few examples are 

provided below, and the complete list is available in Appendix F.

 Biotic Communities: e.g., Rhizophora mangle – Avicennia 

germinans – Laguncularia racemosa / Batis maritima Shrubland,

Avicennia germinans / Batis maritima Shrubland

Biotic Class: Forested Wetland

Areas in this class are characterized by woody vegetation that is generally 6 meters or 

taller. This CMECS class is equivalent to the Forested Wetland Class of FGDC-STD-004

(FGDC 1996b and the Forest/Woodland Class of FGDC-STD-005-2008); however, the 
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palustrine and non-tidal riverine portions of the FGDC-STD-004 class are beyond the 

scope of CMECS.

 Biotic Subclass: Tidal Forest/Woodland – Estuarine or tidal riverine areas with 

greater than 10% tree cover. This cutoff value is the standard employed by 

FGDC-STD-005-2008 for defining the Forest and Woodland Formation Class 

[FGDC 2008].

o Biotic Group: Brackish Tidal Forest/Woodland – Tidal areas 

dominated by tree species that are greater than 6 meters tall and have a 

range of salt tolerance. Salinities may range from 0.5–30.

 Biotic Community: e.g., Picea sitchensis / Lonicera involucrata –

Malus fusca Tidal Woodland [Provisional]

o Biotic Group: Freshwater Tidal Forest/Woodland – Tidal riverine

areas dominated by salt-intolerant tree species that are greater than 6

meters tall. The list of Biotic Communities for this group is long: a few 

examples are provided below, and the complete list is available in

Appendix F.

 Biotic Communities: e.g., Pinus taeda – Nyssa biflora –

Taxodium distichum / Morella cerifera / Osmunda regalis var. 

spectabilis Forest, Nyssa biflora – (Taxodium distichum, Nyssa 

aquatica) / Morella cerifera – Rosa palustris Tidal Forest, 

Taxodium distichum / Carex hyalinolepis Woodland

o Biotic Group: Saltwater Tidal Forest/Woodland – Tidal areas 

dominated by halophytic tree species that are greater than 6 meters tall.

 Biotic Communities: e.g., Tamarisk Tidal Forest [Provisional],

Melaleuca Tidal Forest [Provisional]

Biotic Group: Tidal Mangrove Forest – Tidally influenced, dense,

tropical or subtropical forest with a shore zone dominated by true 

mangroves (and associates) that generally are 6 meters or taller (Figure 

8.17). Dwarf shrub and short mangroves are placed in the Tidal Mangrove 

Shrubland Biotic Group. 

Mangrove Forests (e.g., mangal or mangle) occur along the sheltered 

coasts of tropical latitudes of the Earth, and are commonly found on the

intertidal mud flats along the shores of estuaries, usually in the region 

between the salt marshes and seagrass beds and may extend inland along 

river courses where tidal amplitude is high. Also, mangrove cays may 

occur within the lagoon complex of barrier reefs.
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The list of biotic communities for this group is long: a few examples are 

provided below, and the complete list is available in Appendix F.

 Biotic Communities: e.g., Avicennia germinans Forest,

Conocarpus erectus Forest, Rhizophora mangle – (Avicennia 

germinans, Laguncularia racemosa) Riverine Forest

Figure 8.17. Rhizophora mangle Fringe Forest Biotic Community.

8.3 Status of Biotic Community Units

For some biotic communities, detailed information now exists that could be compiled to 

fully describe them. However, for other biotic communities, more effort is needed in 

developing and analyzing large datasets to statistically categorize biotic communities, 

particularly for cryptic soft-sediment habitats that are characterized by infauna.

Status of Biotic Communities Defined by Vascular Vegetation

Biotic communities that are defined by vascular vegetation (i.e., emergent wetlands, 

shrub-scrub, and forests) are relatively well known and represent accepted FGDC-STD05-2008 associations. Unless marked as “[Provisional]” the listed associations have been 

rigorously defined (over the last twenty years), described, and assigned at least a 

“moderate” level of confidence according to FGDC-STD-05-2008. Descriptions of these 

units are available online at www.natureserve.org/explorer. Those marked 

“[Provisional]” have been identified as potential FGDC-STD-05-2008 units, but have not 
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yet been through the review process to adopt them into the FGDC-STD-05-2008. 

Vegetated biotic communities currently in CMECS have been described for the United 

States only. Plant associations from other countries can be incorporated into the current 

framework for international application.

Status of Biotic Communities Defined by Fauna and Non-vascular Vegetation

All faunal and non-vascular biotic communities listed above are examples of broaddominance types that are known to occur within a given biotic group. These biotic 

communities are considered provisional. The provisional biotic community names are 

presented here as examples of the diagnostic taxa that may provide the basis for more 

rigorously defined biotic communities in the future. These communities are not an 

exhaustive list, and—despite best efforts—these communities may be regionally skewed 

based on the current state of knowledge of these units (and the knowledge of the CMECS 

developers). The provisional, genus-level biotic community names given here can be 

applied for many project objectives (when these biotic communities are identifiable), and 

a significant amount of descriptive information for the listed biotic communities is 

available in the scientific literature.

Users are free to develop and use their own biotic communities as the classification is 

developed. Practitioners and other stakeholders are encouraged to suggest additions and 

refinements, and further communities will be developed through the process described in 

Section 13. 

8.4 Biotic Component Modifiers

The following is a list of modifiers relevant to the Biotic Component. Users are free to 

apply these as appropriate for project goals and as supported by available data. Users are 

not obligated nor limited to the list below. These modifiers are fully described in Section

10. 

 Anthropogenic

o Anthropogenic Impact

 Biogeographic

o Primary Water Source

 Biological

o Associated Taxa

o Community Successional Stage

o Invertebrate Community Organism Size

o Phytoplankton Productivity

o Macrovegetation Productivity

 Physical 

o Energy Direction

o Energy Intensity

o Energy Type

o Seafloor Rugosity
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o Small-scale Slope

o Tidal Regime (Amplitude)

 Physicochemical

o Oxygen

o aRPD 

o RPD

o Salinity (PSS)

o Temperature

 Spatial

o Co-occurring Elements 

o Coral Reef Zone

o Fine Percent Cover 

o Coarse Percent Cover 

o Profile

 Temporal

o Temporal Persistence
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9. Biotopes

CMECS separates out the different aspects of the seascape in a flexible manner, which is 

helpful in satisfying a broad array of users. Components can be applied individually; 

however, when the components are combined, they provide an effective ecological tool 

that can help users understand how abiotic and biotic elements interact in nature. This 

approach is intended to advance understanding of the habitat requirements for biological 

communities and species. Currently our understanding of biotopes in U.S. coastal and 

marine waters is under development, and CMECS provides standards for identifying and 

describing these biotopes. 

9.1 The Biotope Concept

A biotope is defined as the combination of abiotic habitat and associated species (Connor 

1995, 1997; Connor et al. 2003). In this definition, the term habitat refers to a suite of 

environmental factors (such as sediment grain size, physiographic features, and specific 

physicochemical attributes) at a specific location; the term associated species refers to the 

biotic community or group of organisms that occur in that environment (Olenin and 

Ducrotoy 2006).

In CMECS “associated species” is equivalent to the concept of the biotic community 

defined in the Biotic Component (BC). Biotopes differ from biotic communities in that 

environmental features are explicitly used to classify and describe biotopes. It is the 

combination of the species assemblage and specific environmental circumstances that 

defines the biotope. While most species assemblages reflect repeating environmental 

patterns, their identification as biotic communities is not dependent on the co-occurrence 

of a common set of physical or geochemical features. 

Connor et al. (2004) used this biotope concept to develop a comprehensive marine 

classification for Britain and Ireland, and the approach has been adopted for use in 

Europe (Davies et al. 2004). The result is a classification of biotopes defined by explicit 

biological and abiotic parameters—an approach that is quite effective in meeting a 

number of scientific and conservation needs. Example European biotopes include: 

Mytilus edulis and barnacles on very exposed eulittoral rock

Mytilus edulis beds on sublittoral sediment

Nephtys cirrosa and Macoma balthica in variable salinity infralittoral mobile sand

Filamentous green seaweeds on low salinity infralittoral mixed sediment on rock

9.2 Using CMECS to Classify Biotopes

CMECS is ideally suited for the purpose of defining biotopes. CMECS units are the 

building blocks of biotopes. Combinations of features in the BS, AS, WC, GC, and SC 
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may be used to characterize the abiotic environment of biotopes. Biotopes can be 

recognized when individual BC biotic communities are repeatedly associated with unique 

combinations of the abiotic features. Observational or statistical methods may be used to 

identify regularly occurring biological assemblages and the associated physical 

environments.

9.2.1 Classifying Biotopes with Quantitative Data

CMECS has been used to define and map biotopes in Narragansett Bay, Rhode Island 

using field-collected data and statistical clustering techniques. Shumchenia and King 

(2010) identified seven biotopes in Greenwich Bay (an embayment within Narragansett 

Bay) using the substrate, geoform, and biotic community features from CMECS (Figure 

9.1). Although the spatial focus of the study was small, the methodology holds great 

promise for quantitatively identifying and describing biotopes across their entire range.

Identifying biotopes quantitatively across the U.S. is an enormous challenge, which can 

only be met by intensive, in-situ data collection and analysis within the range of marine 

environments. Once biotopes are identified, approaches (such as species suitability 

modeling (as described in Degraer et al. 2008) can be used to inventory species and 

forecast biotope occurrence across their range. Such an effort may take many years to 

achieve, but the output will provide the information that is needed to protect and maintain 

critical coastal and marine resources.

9.2.2 Classifying Biotopes with Observational Information

In the absence of range-wide data, CMECS can be used to qualitatively identify and 

describe biotopes. Information from the literature—and data collected from local and 

regional studies—can be placed in the CMECS framework to describe individual 

biotopes. The Phragmatopoma lapidosa Reefs on High Energy Sand Biotope (Figure 9.2) 

provides an example of how CMECS components can be combined to classify a biotope 

using qualitative information. As individual studies use the CMECS framework to 

identify the concurrence of biological communities and abiotic factors, the information 

can be coalesced to improve understanding of biotopes across their range.
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Figure 9.1. Illustration of how CMECS was used to define Biotopes.

The analysis for Figure 9.1 used CMECS Version 3.1. Changes to the standard in the 

current version (4.0) explain minor differences in terminology. Figure reprinted with 

permission from Elsevier.
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9.3 Describing Biotopes

Biotope descriptions should be developed using the terms and concepts from each of the 

components, expanding on the defining biotic and abiotic features for the biotope. A 

formal biotope description includes information about the diagnostic and characteristics 

species and associated taxa, defining physical features, similar biotopes and how they can 

be distinguished, interactions with other biotopes, geographic range of occurrence, and 

the ecological and societal relevance or importance of the biotope. Repeatability, scales 

of time and space, and relative abundance of the biotopes should also be included in the 

descriptions as appropriate.

The following shaded area provides a sample biotope description.

Biotope: Phragmatopoma lapidosa Reefs on High Energy Sand

Biogeographic Component:

Realm: Tropical Atlantic

Province: Tropical Northwestern Atlantic

Ecoregion: Floridian

Aquatic Setting:

System: Marine

Subsystem: Nearshore

Tidal Zone: Intertidal, Subtidal

Geoform Component:

Tectonic Setting: Passive Continental Margin

Physiographic Setting: Continental/Island Shore Complex

Geoform Origin: Geologic, Biologic

Level 1 Geoform: Beach

Level 1 Geoform Type: Wave Dominated Beach

Level 2 Geoform: Worm Reef

Level 2 Geoform Type: Linear Worm Reef, Patch Worm Reef

Substrate Component:

Substrate Origin: Geologic Substrate

Substrate Class: Unconsolidated Substrate

Substrate Subclass: Fine Unconsolidated Substrate

Substrate Group: Sand, Muddy Sand

Biotic Component

Biotic Setting: Benthic Biota

Biotic Class: Reef Biota

Biotic Subclass: Worm Reef

Biotic Group: Sabellariid Reef

Biotic Community: Phragmatopoma lapidosa Reef
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Description: The brownish mound-like or ridge-like worm reefs that characterize this 

biotope commonly occur in or just outside the surf zone running parallel to highenergy tropical or subtropical beaches, but may occur in other settings as well. In the 

United States, this biotope is most common on the Atlantic coast of southern Florida. 

These reefs have a honeycomb appearance, with a grainy texture that can be crumbled 

by hand. The diagnostic species Phragmatopoma lapidosa is commonly known as the 

“reef-building tubeworm” or “sand-tube worm.” These 15 to 40 millimeter-sized

animals cement sand-sized grains of substrate into 5 to 30 centimeter protective tubes 

that can form extensive reefs through successive colonization and growth of 

conspecifics. The reefs are important ecologically, providing refuge and hard 

substrate in an area of high wave energy. The reefs also play an important geological 

role by decreasing the effects of wave erosion on shores and by contributing to the 

formation and maintenance of barrier islands and beaches. 

Physical Associations: This biotope is associated with turbulent, high-energy areas on 

sand substrates that provide appropriately sized suspended particles for tube 

construction and feeding. These conditions are most commonly found at high-energy 

beaches between the mid-tide level and a depth of 2 meters but can also occur at highvelocity tidal inlets and in other areas, and colonies have been reported at depths to 

100 meters. Stable attachment sites are required for initial colonization, since larvae 

have a difficult time settling into unstable shifting sands. Living or dead conspecifics 

provide a preferred colonization site, but any stable solid object or feature can be used 

for initial settlement. Most reefs occur in tropical and subtropical areas at euhaline 

salinities.

Biological Associations: P. lapidosa reefs support a complex faunal assemblage with 

much higher diversity and abundance than can be found in adjacent sandy non-reef 

areas. A particularly high diversity of crustaceans generally dominates the associated 

macroinvertebrate community, and the crabs Pachygrapsus transversus, Mennipe 

nodifrons, Pilumus dasypodus, or Panopeus bermudensis are notable predators on the 

tube worms themselves. Many other taxa are abundant: barnacles (Tetraclita 

squamosa), sponges, bryozoans, coelenterates, and mollusks also colonize the reefs. 

Demersal and semi-demersal fishes (e.g., Labrisomus nuchipinnis, Scartella cristata, 

and Diplodus holbrooki) are also associated with this biotope. Pistol shrimps 

(Synalphus fritzmuelleri) may be common. Transient visitors foraging in this biotope

include a variety of predatory fish, many of which are commercially or recreationally 

valuable.

Range: Western Atlantic from Florida to Brazil; present (but rare) in the Gulf of Mexico.

Related Biotopes: Sabellaria vulgaris reefs are found in the Western Atlantic north of 

Florida (generally in deeper waters) and constitute a common biotope in Delaware 

Bay and elsewhere. Phragmatopoma californica reefs are found from southern 

California into Mexico. Sabellaria alveolata reefs are found in the Eastern Atlantic 

(e.g., southwestern England, northern France).
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Sources: Zale, A.V., and S.G. Merrifield. 1989. Species profiles: life histories and 

environmental requirements of coastal fishes and invertebrates (south Florida) – reefbuilding tube worm. U.S. Fish Wildlife Service. Biol. Rep. 82(11.115). U.S. Army Corps 

of Engineers, TR EL-82-4.
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10. Modifiers

Modifiers are physicochemical, spatial, geological, biological, anthropogenic, and 

temporal variables with defined categorical values and ranges that are used to describe 

CMECS units. Modifiers can be applied when additional information is needed to further 

characterize an identified unit for individual applications. Modifiers provide additional 

environmental, structural, or biological information about the ecosystem; modifiers are

useful for description and application—but they are not required for classification 

according to the CMECS schema. Modifiers are a dynamic component of the CMECS in 

the sense that users are free to apply additional local modifiers for their project needs as 

long as these are reported and do not conflict with modifiers outlined in this section.

The modifiers are organized by into general modifier types, and then listed alphabetically 

within the given type for easy reference. The general modifier types include 

Anthropogenic, Biogeographic, Biological, Geological, Physical, Physicochemical, 

Spatial, and Temporal. Modifiers within each type are as follows:

o Anthropogenic: Anthropogenic Impact

o Biogeographic: Primary Water Source

o Biological: Associated Taxa, Community Successional Stage, Invertebrate 

Community Organism Size, Productivity

o Physical: Energy (Direction, Intensity, Type), Induration, Seafloor 

Rugosity, Small-scale Slope, Substrate Descriptors, Surface Pattern, Tidal 

Regime (Amplitude), Wave Regime

o Physicochemical: Oxygen, Photic Quality, aRPD and RPD, Salinity, 

Temperature, Turbidity, Turbidity Type, Turbidity Provenance, Water 

Column Stability

o Spatial: Benthic Depth Zones, Co-occurring Elements, Coral Reef Zone, 

Enclosure, Percent Cover Range, Profile, Substrate Layering

o Temporal: Temporal Persistence

10.1 Anthropogenic Modifiers

10.1.1 Anthropogenic Impact

Table 10.1. Anthropogenic Impacts Modifier.

Anthropogenic 

Impact Values Description

Aquaculture Areas and structures where shellfish or finfish are being raised or 

confined for harvest. This may also include fish traps and ponds 

or enclosures.
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Anthropogenic 

Impact Values Description

Contaminated Areas affected by past or present anthropogenic discharge of 

unnatural or excessive amounts of compounds (such as nutrients, 

sewage, metals, pesticides, or other materials) to waters or 

substrates, which results in concentrations significantly higher 

than those attributable to natural loading.

Developed Coastal or marine areas that have been modified by durable and 

persistent human construction (e.g., artificial reef, pier, seawall, 

marina, residence, or drilling platform).

Dredged Landscape that is mechanically altered by the removal of 

sediments or other materials (e.g., shell) in order to deepen or 

widen channels (e.g., for navigation or alteration to hydrology).

Exotic Areas affected by human-mediated introduction of exotic species.

Filled Areas where materials (such as sand or shell) have been placed on 

(or in) an area of coast or a water body.

Impounded/ 

Diverted

Areas where artificial construction impedes, redirects, or retains 

hydrological flow by building or placing barriers (e.g., dams, 

levees, dikes, berms, seawalls, or piers); these structures are 

designed to either retain water or to prevent inundation.

Restored Areas where restoration activities have been conducted; may 

include planted areas.

Scarred Areas of scarring by natural or anthropogenic activities other than 

trawling or harvesting. Examples include ice scouring, vessel 

grounding, prop scarring, or other industrial activities.

Trawled/Harvested Areas affected by past or present trawling or shellfish harvesting.

10.2 Biogeographic Modifiers

10.2.1 Primary Water Source

The Primary Water Source Modifier refers to the provenance of water flowing through or 

into a location. This can range from freshwater inputs (from watersheds and sloughs) to 

seawater exchanges through tidal passes.
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Table 10.2. Primary Water Source Modifier.

Primary Water Source

Values Provenance

Estuary Plume flow that is from the estuary.

Local Estuary Exchange Tidal exchange that is primarily estuarine water.

Local Ocean Exchange Tidal exchange that is primarily marine water at the 

marine end member interface.

Marine Unidirectional flow that is primarily marine water.

River Tidal exchange or plume flow that is primarily river water.

Watershed Flowing freshwater from the upstream watershed.

10.3 Biological Modifiers

10.3.1 Associated Taxa

The Associated Taxa Modifier is used in the Biotic Component to denote the presence of 

biota that are not a classification unit in CMECS; e.g., portunid crabs, groupers, gadids, 

barracuda, herring, all nekton, and other rapidly moving fauna. Further discussions on the 

use of Associated Taxa (as well as examples) are given under Co-occurring Elements, 

Section 10.6.2 below.

10.3.2 Community Successional Stage

The Community Successional Stage modifier is intended for use in the Biotic 

Component, Faunal Bed Class, Soft-sediment Fauna Subclass. In the ecological literature, 

successional stage is a concept used to characterize identifiable points along a continuum 

of sequential—and somewhat predictable—replacements of taxa following a major 

disturbance which opens up a relatively large space. These stages are based in part on the 

differing organism life-history strategies of biota, and in part on their resulting 

modifications to the physical environment (Odum 1969; Ritter, Montagna, and 

Applebaum 2005). Rosenberg (1976) pointed out that the same basic pattern of 

succession is seen in soft-sediment environments in many different parts of the world, in 

response to various stressors (e.g., organic input, temperature stress, or low oxygen), 

noting that species composition (but not the basic pattern) differs among settings. Early 

work on infaunal marine succession recognized that this process is a complex and 

continually varying response to a history of disturbance, and that “there is a complete 

spectrum in nature” (Johnson 1972). Nonetheless, there is (along this spectrum) a 

predictable pattern to benthic community structure that follows levels of stress and 

disturbance, and this is a very useful construct in understanding the environment 
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(Rosenberg 2001). CMECS provides four modifiers for Community Stage in softsediment areas; these have been described previously (Pearson and Rosenberg 1976, 

1978; Rhoads and Germano 1982, 1986; Nilsson and Rosenberg 1997, 2000) and are 

shown in Figure 10.1.

Figure 10.1. Distribution of Benthic Community Stages.

Stages in soft-sediment areas along a gradient of increasing environmental disturbance

from left to right (figure modified from Nilsson and Rosenberg 1997).

Several methods have been developed to identify stages of soft sediment faunal status in 

relation to the concepts of succession. These methods include species identifications and 

comparisons to lists of fauna known to characterize successional stages (Pearson and 

Rosenberg 1976), as well as sediment-profile camera methods that use specific criteria to 

identify infaunal stage or status (Rhoads and Germano 1982, 1986; Nilsson and 

Rosenberg 1997, 2000). All of these approaches use different methods, and they are not 

identical in philosophy or in practical derivation. Further, the strict meaning of 

“successional stages” implies transitions from one group of species to another; this 

transition is difficult to determine based on a single snapshot (which does not provide

information on these transitions over time). Imaging methods that cannot resolve species

contribute to this difficulty as well. However, the basic meanings of the four stages 

described here—when interpreted as a snapshot of community stage in the sense of 

“infaunal status” (rather than as “successional stage” in a strict sense)—provide an 

informative perspective on infaunal communities that can be valuable for interpreting 

condition or habitat quality. Moreover, these stages are comparable over several 

identification methods for fine-grained sediments from temperate and (in some cases) 

sub-tropical climates. Practitioners may refer to regionally appropriate literature for 

further detail.
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Table 10.3. Community Successional Stage Modifier.

Community 

Successional 

Stage Values

Description

Stage 3 These communities are identified by larger, long-lived, deep burrowing fauna or by 

evidence of the activities of those fauna; burrowing activities typically extend 

deeper than 5 centimeters. Characteristic species vary among localities and among 

environments; species can be identified through regionally appropriate literature. 

Common surface expression may include very large tube-building fauna 

(> 3 millimeters in diameter or > 30 mm in length), larger fecal mounds, burrowing 

urchins or ophiuroids, pits or tunnel openings (e.g., crustacean excavations with a 

lumen width of > 1 centimeter), or large digging spoils associated with pits or 

tunnels. Subsurface characteristics include oxygenated or active faunal feeding 

voids at 5 centimeters or deeper, active tunnels (subsurface excavations with a 

lumen width of > 1 centimeter) at depth, or presence of large polychaetes or other 

fauna. Frequently, evidence of smaller, opportunistic fauna will also be present in 

Stage 3 communities; these fauna are not necessarily eliminated by larger fauna. If 

evaluating sediment profile images, guidelines from Rhoads and Germano (1982, 

1986) can be followed, or the Nilsson-Rosenberg Benthic Habitat Quality (BHQ) 

metric (Nilsson and Rosenberg 1997, 2000) can be used (Stage 3 will have BHQ > 

10). Extensive bioturbation will be evidenced by deep RPD and aRPD depths.

Stage 2 Communities are characterized by fauna of intermediate sizes typically inhabiting 

the upper 2–4 centimeters of sediment. This stage is considered transitional and is 

often variable; in a percentage of samples it will be difficult to clearly distinguish 

Stage 2 from other stages within the continuous spectrum presented by natural 

environments. Regional literature identifying species typical of Stage 2 may be 

referenced. Surface evidence of Stage 2 communities includes openings to small 

burrows (defined as excavations with a lumen width < 1 centimeter) and the 

presence of mid-sized tube dwelling fauna (e.g., robust Ampelisca tube mats; tubes 

> 2 millimeters in diameter; or tubes longer than 30 millimeters if very thin). 

Subsurface evidence includes burrows of polychaetes or other fauna in the upper 

2–4 centimeters of sediment, small shallow-dwelling opportunistic bivalves, and 

small feeding voids in the upper 4 centimeters of sediment. If examining sediment 

profile images, guidelines from Rhoads and Germano (1982, 1986) can be followed 

or the Nilsson-Rosenberg BHQ metrics (Nilsson and Rosenberg 1997, 2000) can 

be used (BHQ for Stage 2 will range from 5 to 10).

Stage 1 These associations are inhabited by small opportunistic fauna (e.g., capitellids and

spionids) in the upper centimeter of sediment. Larger fauna are not present, 

although juvenile individuals of larger species may occur. Names of small, 

opportunistic local species typical of Stage 1 are available in the regional literature. 

Surface expressions include small tubes (< 2 millimeters in diameter) of 

polychaetes or other fauna, or evidence of oligochaete burrowing activities. 

Subsurface evidence of either small worms or small burrow structures will 

primarily occur in the upper centimeter of sediment. If examining sediment profile 

images, guidelines from Rhoads and Germano (1982, 1986) can be followed or the 

Nilsson-Rosenberg BHQ metrics (Nilsson and Rosenberg 1997, 2000) can be used 

(Stage 1 BHQ values will range from 2 to < 5). Bioturbation depths will be 

shallow, with an aRPD depth typically > 2 millimeters to < 2 centimeters.

Stage 0 These oligozoic soft-sediment areas show little evidence of multi-cellular life; 

however, benthic samples that are retrieved and processed under magnification 
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Community 

Successional 

Stage Values

Description

from Stage 0 stations will generally produce low numbers of small macrofauna or 

meiofauna. Multicellular fauna will not be obvious to the unassisted eye when 

examining sediment, and it will not be obvious in high-resolution images of the 

seafloor. Bacterial mats may be present. If examining sediment profile images, 

guidelines from Rhoads and Germano (1982, 1986) can be followed or the NilssonRosenberg BHQ metrics (Nilsson and Rosenberg 1997, 2000) can be used (BHQ 

values for Stage 0 will range from 0 to 1.99). No evidence of active bioturbation 

exists, and aRPD depths are typically < 2 millimeters.

10.3.3 Invertebrate Community Organism Size

The Invertebrate Community Organism Size modifier is intended for use in the Biotic 

Component, Faunal Bed Class. Ecological theory of community succession and 

disturbance posits that less frequently disturbed environments will provide the stability to 

support longer-lived communities of larger organisms, while frequently disturbed 

environments will be characterized by smaller and shorter-lived organisms. Faunal Bed 

communities are often complex, with a wide range of individual organisms and species 

occurring in many sizes to fill a variety of ecological niches. CMECS provides a coarse 

set of Organism Size Modifiers to describe Faunal Bed communities through sizes of the 

larger organisms that are evident in an observational unit. Many different methods have 

historically been proposed to distinguish macrofauna from megafauna—ranging from 

“visible to the unassisted eye,” to retention on various screen sizes, to inclusion only of 

much larger organisms. The CMECS criterion used to identify megafauna is a body size 

> 1 cm (in the smallest dimension). Importantly, this modifier describes the defining, 

significant, or dominant organisms that best characterize a community, recognizing that 

most communities include a variety of organisms that occur in both large and small 

individual sizes.
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Table 10.4. Invertebrate Community Organism Size Modifier. Note that 

measurements of the smallest dimension of body size (e.g., height, width) will be 

misleading when the measured fauna are unusually flat or long, e.g., sand dollars, sea 

fans, nemerteans. Practitioners should consider this in assigning invertebrate community 

organism sizes, and should assign appropriately larger sizes in these cases.

Invertebrate 

Community 

Organism Size

Values

Description

Large Megafauna Benthic invertebrate communities that are dominated by 

organisms that typically reach a body size of greater than 3 

centimeters in the smallest dimension (e.g., height, width), with 

this measurement not to include the length of slender, lateral 

protrusions (such as arms or tentacles).

Megafauna Benthic invertebrate communities that are dominated by

organisms that typically reach a body size of > 1 to 3 centimeters

in the smallest dimension (e.g., height, width), with this 

measurement not to include the length of slender, lateral 

protrusions (such as arms or tentacles). These communities may 

be identified by evidence of these fauna (e.g., large mounds or pit 

or tunnel openings of > 1 to 3 centimeters).

Large Macrofauna Benthic invertebrate communities that are dominated by organisms 

with a body width (smallest dimension) of > 2 millimeters to 1 

centimeter; living organisms larger than this size range are rare in 

these infaunal or epifaunal associations.

Small Macrofauna Benthic invertebrate communities that are dominated by organisms 

with a body width (smallest dimension) of > 0.5 to 2 millimeters; 

living organisms larger than this size range are rare in these

infaunal or epifaunal associations.

Meiofauna These benthic invertebrate communities are dominated by 

organisms with a body width (smallest dimension) of 0.5 mm or 

less, that would typically pass through an 0.5 mm sieve but be 

retained on an 0.25 mm sieve. Living organisms larger than this 

size range are rare in the infaunal or epifaunal association; the 

modifier may be applied to any classification unit within Faunal 

Bed.

10.3.4 Productivity

Productivity is a general categorization of the level of primary productivity—that is, the 

photosynthetic activity of autotrophs, including plankton, benthic microalgae, 

macroalgae, and vascular vegetation. The density of phytoplankton can be estimated by 
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measuring the level of chlorophyll a in the water column, since all phytoplankton contain 

this fluorescent pigment enabling the harvesting of light. This measure also indirectly 

reflects the abundance of dissolved labile macronutrients (DIN and DIP), which 

phytoplankton use in photosynthetic processes. In broad terms, chlorophyll a content 

reflects net productivity, giving an indication of the trophic status of the system or the 

balance of primary production; secondary consumption by zooplankton, fish, and 

predators; and export from the system. Productivity is indicated by chlorophyll a 

concentration in water columns and by total biomass in macroalgal and rooted vascular 

plant communities. For water column phytoplankton communities, the modifier 

categories were derived, with modification, from the NOAA Estuarine Eutrophication 

Survey (NOAA 1997).

Table 10.5. Phytoplankton Productivity Modifier.

Phytoplankton Productivity

Values Chlorophyll a Level (μg/L)

Oligotrophic < 5

Mesotrophic 5 to < 50

Eutrophic ≥ 50

Table 10.6. Macrovegetation Productivity Modifier.

Macrovegetation Productivity

Values Biomass (mg dry wt/m2

)

Oligotrophic < 50

Mesotrophic 50 to < 1,000

Eutrophic ≥ 1,000

10.4 Physical Modifiers

10.4.1 Energy

To describe energy, CMECS follows a simplification of the concept introduced by 

Dethier (1990), which is also employed in several subsequent classifications (Howes, 

Harper, and Owens 1994; Holthus and Maragos 1995; Schoch 1999; Allee et al. 2000; 

Resource Information Standards Committee 2002). The ShoreZone classification work of 

Schoch (1999) provides the basis for a detailed nearshore classification of energy on 

land-sea margins, using a very simple energy classification related to the force of water 

movement (whether tidal, wave, or current). 
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Energy determines the kinds of animals and flora that can maintain attachment or 

position in a particular habitat. Energy level also determines the nature of the substrate by 

suspending, transporting, and sorting fractions of substrate particulates of specific grain 

sizes. Energy can shape bedforms (e.g., sand waves and sand ripples) and erode or 

accrete geoforms. Highly impacted areas are typified by the presence of erosive features, 

such as beach scarps or bare rock substrates.

The terminology of “degree of exposure” is common in many other classifications, but it

is not used in CMECS—which favors the more accurate term energy. Exposure is a 

subjective term that includes qualification of both the direction of the feature (relative to 

hydrodynamic energetic) and the energy of the system (at a given point in time). An 

exposed and open coast may in fact be very quiescent, depending on the season or 

direction it is facing. Energy, along with a quantitative scale, is a more accurate indicator 

of the actual force that impacts a particular coastal or marine feature.

Energy Modifiers apply to the Substrate, Biotic, Geoform, and Water Column 

Components of the classification. Within the intertidal and subtidal benthic zones, energy 

acts to shape the geoforms. Within the water column, the energy is related to current 

speeds (in knots), wave intensity, and tidal motions. Energy Modifiers in CMECS are 

described by direction, intensity, and type.

Energy Direction

Energy can be classified according to its principal direction of travel or influence. In the 

case of tidal energy, this is generally an oscillation between onshore and offshore 

motions. In the case of currents and waves, the energy is usually directional.

Table 10.7. Energy Direction Modifier.

Energy Direction

Values Description

Baroclinic Motion along lines of equal pressure within the water column.

Circular Motion in a closed, circular form.

Downward Descending and perpendicular to the sea surface or bottom.

Horizontal Parallel to the sea surface or bottom.

Mixed Combination of more than one of above directions.

Seaward On land, water currents following a topographic gradient toward 

the sea.

Upward Ascending and perpendicular to the sea surface or bottom.
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Energy Intensity

Energy Intensity is classified into four categories as shown on Table 10.8.

Table 10.8. Energy Intensity (Current) Modifier.

Energy Intensity 

Values Description

Very Low Current 

Energy

Area experiences little current motion under most conditions.

Low Current

Energy

Area typically experiences very weak currents (0–1 knots).

Moderate Current 

Energy

Area regularly experiences moderate tidal currents (> 1–3 

knots).

High Current 

Energy

Area regularly experiences strong currents (> 3 knots).

Energy Type

The Energy Type Modifier ia adapted from Dethier (1990) and Zacharias et al. (1998) 

with type categories as described in Table 10.9.

Table 10.9. Energy Type Modifier.

Energy Type

Values Description

Current Coherent directional motion of the water.

Internal Wave Vertical and transverse oscillating water motion—below the 

surface—due to seismic energy or a pressure differential.

Surface Wave Vertical and transverse oscillating surface water motion due to 

wind or seismic energy.

Tide Periodic, horizontally oscillating water motion.

Wind Coherent directional motion of the atmosphere.

10.4.2 Induration 

The stability of the substrate is a strong determinant of the suitability of an area for 

colonization by sessile organisms, and for feeding or burrowing activities by benthic 

epifauna and infauna. The Induration Modifier can be used to describe the hardness or 

amount of consolidation of bottom sediments (Substrate Component units). Induration is 
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often measured with acoustic tools. The following categories are adopted from Greene et 

al. (2007). 

Table 10.10. Substrate Induration Modifier.

Substrate Induration Values Definition

Hard Strongly consolidated fine sediment with 

low water content, or rock outcrop, or 

bedrock.

Mixed A blend of hard and soft substrate 

materials.

Soft Loose, fine, unconsolidated, or sedimentcovered substrate with a high water content.

10.4.3 Seafloor Rugosity

Seafloor Rugosity, a measure of surface "roughness", is applicable at several scales using 

different measures (e.g., bathymetric x-y-z data, measured transect data, video 

data). Rugosity is derived as the ratio of surface area to planar (flat) area for a grid cell, or 

as the ratio of surface area to linear area along transects, and is calculated as follows:

fr = Ar/ Ag

where Ar is the real (true, actual) surface area and Ag is the geometric surface area

(IUPAC 1997).

Values for Seafloor Rugosity are taken from Greene et al. 2007. The five rugosity types 

and their associated numeric values are given in Table 10.11.
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Table 10.11. Rugosity Modifier.

Rugosity Values Rugosity Range

Very Low 1.0 to < 1.25

Low 1.25 to < 1.50

Moderate 1.50 to < 1.75

High 1.75 to < 2.00

Very High ≥ 2.00

10.4.4 Small-scale Slope

The Slope Modifier refers to the angle of the substrate at a scale appropriate for the 

feature being described; Greene et al.’s (2007) geological classification is followed here 

to characterize slope.

Table 10.12. Slope Modifier.

Slope Values Vertical Angle (Degrees)

Flat 0 to < 5

Sloping 5 to < 30

Steeply Sloping 30 to < 60

Vertical 60 to < 90

Overhang ≥ 90

10.4.5 Substrate Descriptors

The Substrate Component describes substrate size and composition, considering substrate 

origin as Geologic, Biogenic, and Anthropogenic. The Geologic classifications follow 

Wentworth (1922) and Folk (1954) to describe particle sizes and mixes, but do not 

consider geologic composition or several other important attributes. Substrate descriptors 

provide consistent terminology to meet these needs. Certain substrate descriptors may be 

used for other applications as well, e.g., Well-Mixed, Patchy, and Well-Sorted can be 

used to describe biotic communities or other units.
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Table 10.13. Substrate Descriptor Modifier.

Substrate Descriptor

Values Description

Carbonate Geologic Origin particles or substrates composed mainly of 

carbonate minerals, e.g., limestone, dolostone.

Compacted Unconsolidated sediments with very little water content and a 

hard, packed form that resists penetration and resuspension. 

This is one of several terms that are used in CMECS to 

describe the fluid consistency of substrates.

Floc A layer of very fine particles suspended in the water column 

just above firmer sediment. This is often most apparent with 

visual or imaging techniques, and may appear as a turbid or 

cloudy layer above a more defined sediment surface. This is 

one of several terms that are used in CMECS to describe the 

fluid consistency of substrates.

Fluid Substrate with high water content. When a palmful of 

sediment is squeezed in the hand, most or all flows through 

the fingers after full pressure (Schoeneberger et al. 2002). 

This is one of several terms that are used to describe the fluid 

consistency of substrates in CMECS.

Gas Subsurface bubbles of gas, possibly resulting from 

methanogenesis or other biogeochemical processes, are 

present. Escaping gas may or may not express at the sediment 

surface. 

Mobile Bedded sediments which regularly resuspend and/or move 

with local hydrodynamics due to the density, grain size, 

shape, and/or high water content of the sediment, or due to 

the higher hydrodynamic energy experienced in the local 

area. This term is used in CMECS to describe or predict 

behavior of substrates.

Non-mobile Bedded sediments which do not regularly resuspend and/or 

move with local hydrodynamics due to the density, grain size, 

shape, and/or compaction (low water content) of the sediment 

particles, or due to the lower hydrodynamic energy 

experienced in the local area. This term is used in CMECS to 

describe or predict behavior of substrates.

Mud Clasts Compacted or consolidated fragments (clumps, lumps, balls, 

shards, etc.) of mud or clay, typically occurring at the 

sediment surface, with diameters of millimeters to < 1 meter.

Patchy Different elements within a sample, observational unit, or 

reporting unit are grouped into clusters or patches at the scale 

of the sample or unit. “Patchy” implies that clusters of 

elements or particles are arranged in a haphazard manner, as 

clusters of pebbles scattered on sand. This is one of several 
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Substrate Descriptor

Values Description

terms used in CMECS to describe unit variability.

Pelagic Clay Deep sea Geologic Substrates composed primarily of aeolian 

deposits, volcanic ash, and other non-biogenic materials that 

sink into the very deep oceans, or may be generated in the 

deep oceans. Pelagic Clays contain less than 30% ooze 

materials (tests, shells, and frustules of plankters) and are 

found in areas of low surface productivity.

Red Clay A type of Pelagic Clay composed primarily of aeolian dust, 

with various marine-generated particles mixed in (fish bones, 

teeth, authigenic mineral deposits). Red clays are 

distinguished by their characteristic bright red or brown color 

and are found in the deepest and most remote ocean areas.

Red Clay contains less than 30% ooze materials.

Siliciclastic Geologic Substrate Origin particles or substrates composed 

primarily of silicate minerals e.g., quartz, sandstone, siltstone.

Sulfidic Substrate in which bacterial sulfate reduction is an important 

biogeochemical process; this generally occurs in anaerobic 

environments and is often identifiable by a very low 

reflectance black or blue color, and a characteristic “rotten 

egg” odor when sediments are examined in air.

Volcaniclastic Geologic Origin particles or substrates composed primarily of 

volcanic rock, crystals, glassy pumice, ash, or other volcanic 

products.

Volcanic Ash A substrate or substrate layer composed primarily of volcanic 

dust and volcanic ash, often with various aeolian or marinegenerated particles mixed in. In areas of the deep sea, where 

terrigenous input and bioturbation are limited, Volcanic Ash 

may be present in distinct layers at depth in the substrate 

matrix (see the “Layers” modifier).

Well-mixed Different elements within a sample, observational unit, or 

reporting unit are well-mixed or poorly-sorted at the scale of 

the sample or unit. Well-mixed implies that elements or 

particles are completely and relatively evenly intermingled, 

e.g., Granule/Sand/Mud particles in an area with high 

bioturbation. This is one of several terms used in CMECS to 

describe unit variability. Note that CMECS does not use the 

equivalent geological term “Poorly-Sorted”, because the 

descriptor may be used to describe distributions of nongeological features (such as biological communities or 

Geoform Component structures).

Well-sorted Different elements within a sample, observational unit, or 

reporting unit are separated into different areas at the scale of 

the sample or unit. Well-sorted implies that elements or 
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Substrate Descriptor

Values Description

particles are (or have been) separated and arranged in a nonhaphazard manner, as an area of Coarse Sand adjacent to an 

area of Clay. This is one of several terms used in CMECS to 

describe unit variability.

10.4.6 Surface Pattern

The surface of the seafloor may be flat (on a scale of centimeters or meters), or it may be 

characterized by roughness or pattern. The Substrate Component describes substrate size 

and composition, while the Geoform Component describes texture or shape—including 

the Surface Pattern Modifier. These roughness patterns may have physical origins (e.g., 

caused by wave or current action) or biological origins (due to activities of life forms, 

e.g., mounds or tunnels). Physically influenced bedforms may appear as regularly spaced 

“sand ripples” (with a wavelength on the order of centimeters), which may be indicative 

of wave oscillations or of current flows. Physical energy in soft-sediment areas may 

occur through riverine flow or tidally driven flow, leading to erosion and deposition of 

mobile sediment layers.

Table 10.14. Surface Pattern Modifier.

Surface Pattern 

Values Description

Biological Roughness appears due to bioturbation, fecal mounds, 

tunneling, feeding or locomotory activities of megafauna, or 

other faunal activities. Further characterization of biological 

features is described in the Biotic Component.

Irregular Sediment surface has a perceptible roughness or texture that 

is non-regular in either frequency, direction, or amplitude.

Physical Roughness appears due to water motion, but the nature of the 

roughness is other than Rippled.

Rippled Closely spaced, regular, repeating, vertical variations in the 

height of a sandy or muddy bottom, with a very short 

wavelength on the order of centimeters. A rippled substrate is 

generally caused by the physical processes of water motion.

Scarred Roughness appears due to localized sediment disturbance 

resulting either from natural causes (e.g., slumps) or 

anthropogenic causes (e.g., anchor scars, propeller scars, 

trawl scars, or other fishing gear scars), but not as an artifact 

of camera or sampling gear deployment.
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Surface Pattern 

Values Description

Smooth No perceptible roughness or texture to sediment surface at 

scales of less than 1 meter.

10.4.7 Tidal Regime (Amplitude)

The Tidal Regime Modifier refers to the height difference between mean high tide and 

mean low tide at the coast. The mean range gives a proxy for the energy and flow 

associated with tidal motions. Tidal Regime is shown in Table 10.15.

Table 10.15. Tidal Regime (Amplitude) Modifier.

Tidal Regime 

(Amplitude) Values Tidal Range (amplitude in meters)

Atidal < 0.1

Microtidal 0.1 to < 0.3

Minimally Tidal 0.3 to < 1

Moderately Tidal 1 to < 4

Macrotidal 4 to < 8

Megatidal ≥ 8
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10.4.8 Wave Regime (Amplitude)

This modifier is intended to quantify intensity of wave energy by amplitude, and can be 

applied on any time scale, as specified by the user.

Table 10.16. Wave Regime (Amplitude) Modifier.

Wave Regime Values Wave Height (amplitude in meters)

Quiescent < 0.1

Very Low Wave Energy 0.1 to < 0.25

Low Wave Energy 0.25 to < 1.0

Moderate Wave Energy 1.0 to < 2.0

Moderately High Wave 

Energy

2.0 to < 4.0

High Wave Energy 4.0 to < 8.0

Very High Wave Energy ≥ 8.0

10.5 Physicochemical Modifiers

10.5.1 Oxygen

Oxygen concentration is an important water column modifier. Oxygen is critical to 

aerobic organisms and to aerobic processes (such as chemical oxidation and microbial 

respiration). Dissolved oxygen levels change daily in a dramatic way in systems such as 

estuaries, where they often go from hypoxic (at night) to saturated (during the day). The 

Oxygen Regime Modifier is intended for use in reporting persistent oxygen conditions, or 

can be used to explain variable regimes as described by the user. Oxygen levels are

determined according to the following ranges, for the time scales and durations specified 

by the user; practitioners may specify, e.g., “oxygen varies from highly oxic during 

daylight hours to severely hypoxic at night”. Furthermore, practitioners should note that 

oxygen saturation varies with temperature and pressure.
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Table 10.17. Oxygen Regime Modifier.

Oxygen Regime Values Oxygen Concentration (milligrams/Liter)

Anoxic 0 to < 0.1

Severely Hypoxic 0.1 to < 2

Hypoxic 2 to < 4

Oxic 4 to < 8

Highly Oxic 8 to < 12

Very Oxic ≥ 12

10.5.2 Photic Quality

Photic quality is a highly variable parameter. In many cases, water is clear and 

downwelling light penetration extends the photic zone to the bottom of the water column. 

In cases of reduced water clarity, light is highly attenuated. Photic exposure depends on 

the depth, sun angle, cloud cover, time of year, and other factors. Moreover, the depth of 

the shift from photic to aphotic occurs at different points in the water column, depending 

on the ecosystem, watershed, and suspended substances reducing water clarity.

Vertical zones are evaluated relative to the penetration of light (photic and aphotic) for 

both water column and benthic components. The depth of the photic zone can also be 

calculated from ocean color imagery using satellite algorithms (Lee et al. 2007).

Table 10.18. Photic Quality Modifier.

Photic Quality 

Values Condition

Aphotic Region of the water column where no ambient light penetrates, no 

photosynthesis occurs, and animals cannot make use of visual cues 

based on even reduced levels of ambient light. In oceans, this zone 

typically lies below 500–1,000 meters of depth. In turbid estuaries, 

this zone may be very shallow.
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Photic Quality 

Values Condition

Dysphotic Region of the water column, below the compensation depth, that 

receives less than 2% of the surface light; plants and algae cannot 

achieve positive photosynthetic production in this region, but some 

ambient light does penetrate such that animals can make use of 

visual cues based on reduced levels of ambient light.

Photic Region of the water column where ambient light is > 2% of surface 

light and phototrophic organisms can photosynthesize.

Seasonally Photic An area that regularly varies between photic and dysphotic/aphotic.

10.5.3 aRPD and RPD

The apparent Redox Potential Discontinuity (aRPD) is a measurement of the depth of the 

“color break,” that is, the maximum color difference below the sediment-water interface 

at which lighter-colored (tan, brown, beige, yellow, or red), more-oxidized surface 

sediments transition into darker-colored (grey, black, or blue-black), more-reduced

deeper sediments. The depth of the aRPD is easily measured, and it has been found to be 

an extremely useful parameter in characterizing certain biogeochemical aspects of the 

sedimentary environment. For instance, the aRPD represents the depth at which iron 

exists as colored, insoluble, ferric hydroxides, which dissolve into solution as iron 

monosulfides in a reducing environment, e.g., in the presence of sulfate reduction (Teal et 

al. 2009). 

The aRPD is strongly correlated to the true RPD depth (Grizzle and Penniman 1991;

Rosenberg et al. 2001), which is the depth where Eh (measured sediment 

reduction/oxidation potential) is zero. Both values are very useful as proxies for 

bioturbation (because the values are extended deeper by the effects of bioturbating 

fauna), and both are correlated to bottom-water dissolved-oxygen concentration 

(Rosenberg 1977; Diaz, Cutter, and Rhoads 1994; Cicchetti et al. 2006). The aRPD can 

be measured with a variety of techniques including retrieval of cores, sediment profile 

imaging, and direct observation. The RPD can be measured using microelectrodes, either 

in retrieved cores or in situ.

 RPD (centimeters) – The RPD is measured with electrodes, and is reported in 

centimeters.

 aRPD depth (centimeters), muddy sediments – The aRPD depth is measured at 

the color transition based on direct observation or from images, and it can be 

reported in centimeters or following the terms defined below (from Nilsson and 

Rosenberg 1997). These modifier terms apply only to sediments that contain some 

mud; aRPD depths manifest differently in sand sediments that are dominated by 

different diffusional processes and rates.
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Table 10.19. aRPD Depth Modifier.

aRPD Depth 

Values aRPD Depth (centimeters)

Zero 0.0

Diffusional > 0.0 to 1.0

Shallow > 1.0 to 2.0

Moderate > 2.0 to 3.5

Deep > 3.5 to 5.0

Very Deep > 5

10.5.4 Salinity

Salinity is considered a classifier for the Water Column Component, i.e., it is an essential 

parameter for measurement in order to effectively classify the water column. However, 

users may wish to apply the CMECS terminology for salinity within other components 

when the water column itself is not being classified. The salinity ranges are repeated here 

in the modifier section to allow this convenience for users.

Table 10.20. Salinity Regime Modifier.

Salinity Regime Values Salinity (Practical Salinity Scale)

Oligohaline < 5

Mesohaline 5 to < 18

Lower Polyhaline 18 to < 25

Upper Polyhaline 25 to < 30

Euhaline 30 to < 40

Hyperhaline ≥ 40

10.5.5 Temperature

As with salinity, temperature is considered a classifier for the Water Column Component, 

i.e., it is an essential parameter for measurement in order to effectively classify the water 

column. Likewise, users may wish to apply the CMECS terminology for temperature 

within other components when the water column itself is not being classified. The 

temperature ranges are repeated here in the modifier section to allow this convenience for 

users.
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Table 10.21. Temperature Range Modifier.

Temperature Range Values Degrees (

oC)

Frozen/Superchilled ≤ 0

Very Cold 0 to < 5 (liquid)

Cold 5 to < 10

Cool 10 to < 15

Moderate 15 to < 20

Warm 20 to < 25

Very Warm 25 to < 30

Hot 30 to < 35

Very Hot ≥ 35

10.5.6 Turbidity

Turbidity is a factor of the suspended solids and color within the water column, and it

affects light attenuation and the depth to which light penetrates in the water column. This 

is critically important for autotrophs that convert light to photosynthetic products. 

Turbidity also has important effects on visual hunting and predation avoidance. While 

turbidity is frequently reported in Nephelometric Turbidity Units (NTUs), CMECS 

establishes categories for turbidity based on Secchi disk depth; it would be difficult to 

standardize turbidity by NTUs due to regional variations in background measurements. 

Secchi disk observations are commonly used in the marine environment.

Table 10.22. Turbidity Modifier.

(as measured by Secchi depth)

Turbidity Values Secchi Depth (meters)

Extremely Turbid < 1

Highly Turbid 1 to < 2

Moderately Turbid 2 to < 5

Clear 5 to < 20

Extremely Clear ≥ 20

10.5.7 Turbidity Type and Provenance

There are two additional Turbidity Modifiers: Type and Provenance. The provenance of 

the attenuating substance―whether the reduced water clarity is derived from chlorophyll 

pigments (e.g., phytoplankton blooms), from color due to dissolved substances in the 

water (e.g., gelbstoff or tannins), from imported mineral terrigenous sediments, or from 
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carbonate particulates in resuspension—is an important qualitative characteristic of 

turbidity. This qualitative assessment can be used in addition to a qualitative or 

quantitative evaluation of the degree of turbidity in the water column.

Table 10.23. Turbidity Type Modifier.

Turbidity Type Values Definition

Carbonate Particulates Attenuation produced by suspended 

precipitated CaCO3 in the water column, 

generally creating an opaque “milky” 

appearance.

Chlorophyll Attenuation produced by chlorophyll a, b, 

c, or d as constituents of live phytoplankton 

in the water column.

Colloidal Precipitates Dispersed particulates that precipitate out 

of the water to form aggregations such as 

marine snow.

Mineral Particulates Attenuation produced by suspended 

inorganic sediments derived from soil and 

rock weathering.

Detritus Attenuation due to larger particles of 

organic detritus in suspension.

Dissolved Color Substances dissolved in water that have

color.

Mixed Attenuation due to a variety of the above 

sources and substances.

Table 10.24. Turbidity Provenance Modifier.

Turbidity Provenance Values Definition

Allochthonous Originating outside of the system and 

transported into the system.

Autochthonous Generated in situ by biogenic processes 

(e.g., phytoplankton bloom).

Marine Origin Materials, water, or energy originating in 

the ocean.

Precipitated Solutes such as calcium carbonate that 

precipitate out of solution.

Resuspended Deposited materials mixed into the water 

column by currents (e.g., bottom 

sediments).

Terrigenous Origin Materials, water, or energy in a water body 

resulting from land drainage or wind 

deposits.
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10.5.8 Water Column Stability

Water column stability can be characterized as stratified, partially mixed, and wellmixed. This structure is defined by density differentials from bottom to surface, as shown 

in the table below. Water Column Stability is assessed using the more universally applied 

delta Sigma-t to calculate stability, which incorporates salinity, temperature into the 

calculation of density and adjusts for adiabatic effects (Pond and Pickard 1983). The 

Stability Regime modifier compares the calculated δ Sigma-t, or the relative density of 

two water parcels by subtraction of the density of the surface layer from the density of the

deeper layer. If the density difference equals or exceeds 0.125, the water column is 

considered to be vertically stable; if it differs by less than 0.125, and density is 

homogeneous between the upper and lower layers, the water column is classified as wellmixed. If the density difference is less than 0.125 and variable between the two layers, 

the water column is classified as partially mixed. 

Table 10.25. Water Column Stability Regime Modifier.

Water Column Stability Regime

Values δ Sigma-t relative to surface density

Partially stratified < 0.125 and variable

Stratified ≥ 0.125

Well-mixed < 0.125 and homogeneous

10.6 Spatial Modifiers

10.6.1 Benthic Depth Zones

The depths of benthic zones vary depending on regional geology and turbidity. It is often 

useful to describe a specific depth or range of depths for the bottom, and the CMECS 

Benthic Depth Zone Modifiers represent the major divisions in a gradient from land to 

the deep ocean bottom. They are generally based on the zones in which surf or ocean 

swell influences bottom communities, lower limits of vegetation (such as kelp), overall 

photic availability, and temperature. The zones within this category are drawn or adapted 

from Greene et al. (2007) and Connor (1997). The following definitions are intended as 

guidance for adaptation of depth ranges to regional environmental conditions:

 Littoral – All areas that are episodically exposed to air; intertidal.

 Infralittoral – Subtidal areas within the photic zone, often characterized by 

macroalgae or rooted vascular plants. Divided into shallow and deep zones.
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 Circalittoral – Subtidal areas below the photic zone, generally characterized by 

animal communities (although very sparse algae may be present).

Table 10.26. Benthic Depth Zone Modifier.

Benthic Depth Zone

Values Approximate Depth Range (meters)

Littoral Intertidal

Shallow Infralittoral 0 to < 5

Deep Infralittoral 5 to < 30

Circalittoral 30 to < 200

Mesobenthic 200 to < 1,000

Bathybenthic 1,000 to < 4,000

Abyssalbenthic 4,000 to < 6,000

Hadalbenthic ≥ 6,000

10.6.2 Co-occurring Elements

Nature is inherently a mixture or a continuum. CMECS provides an ecologically 

meaningful methodology to classify nature into discrete environmental types using 

consistent threshold values that define primary classification units. However, in natural 

coastal and marine settings, less abundant, co-occurring (or secondary) features are 

frequently mixed into these primary classification types at some level beneath a 

classification threshold. Therefore, these co-occurring features are not recognized in the 

syntax of the primary classification. In some situations, project goals may require 

identification of these co-occurring features and associated taxa. In other situations, 

identification of co-occurring materials, taxa, or mixes may detract from project goals.

CMECS provides a modifier, Co-occurring Elements, for identification of secondary 

CMECS classification units that are mixed into a primary classification unit at a level 

below the classification threshold. Co-occurring Elements are used in the hierarchical 

Biotic and Substrate Components when the primary feature and the co-occurring feature 

are both units in that same Component. Examples of Co-occurring Elements may include 

mixes such as:

 An observational unit where Geological Substrate Origin and Anthropogenic 

Substrate Origin coexist (e.g., a 5% cover of large Plastic/Trash on top of a 

dominant Fine Sand Substrate):

o Classification – Geologic Substrate, Substrate Subgroup Fine Sand 
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o Co-occurring Element Modifier – Anthropogenic Substrate, Substrate 

Subclass Plastic/Trash Rubble 5% cover

 An observational unit where two Biotic Groups are present. Consider a seafloor 

image with dominant Larger Deep-Burrowing Fauna, but also containing a cluster 

of sponges:

o Classification – Benthic Biota, Faunal Bed, Soft Sediment Fauna, Larger 

Deep-Burrowing Fauna

o Co-occurring Element Modifier – Biotic Group, Sponge Bed

CMECS also provides another modifier, Associated Taxa (see Section 10.3.1 above), to 

identify biota that are present in an observational unit, but do not constitute a CMECS 

classification unit. Associated Taxa may be predators, rapidly-moving fauna, or other 

biota that are not identifiable as Biotopes or Biotic Groups.

Examples of Associated Taxa may include mixes such as: 

- An observational unit where Mussel Beds on mud are the dominant Fauna, and 

where fish and crab predators are common:

Classification – Benthic Biota, Faunal Bed, Soft Sediment Fauna, Mussel 

Bed

Associated Taxa Modifier – fish (Tautoga) and crabs (Callinectes)

Co-occurring Elements and Associated Taxa follow the conventions adopted for all 

modifiers. This convention allows any CMECS classification unit to be used within its 

appropriate component as a Co-occurring Element modifier to indicate a mixture, and 

allows any type of organism to be included in the Biotic Component as Associated Taxa. 

When evaluating mixes, the spatial scale of the variability of the mixture (the “patch 

size”) becomes an important concept. Consider a sand seafloor spotted in a seemingly 

haphazard pattern with a scattered mosaic of patches of broken shell material that average 

1 meter x 1 meter in size. Different observational methods—for example, a 10 

centimeters x 10 centimeters grab, a 150 centimeters x 200 centimeters still image, or a 

500 meters acoustic swath—will view these shell patch sizes differently. Also, the 

reporting unit for the project may differ from the observational unit, further complicating 

the description of mixes. Below the minimum mapping unit size, these shell patches 

could be considered Co-occurring Elements. However, at the point where the patches 

exceed the minimum mapping unit the shell patches would be large enough to be 

classified as separate reporting units with a new label—and not as a “mix” or Cooccurring Element within an observational or reporting unit.

In many projects, Co-occurring Element Modifiers (and Associated Taxa Modifiers) will 

be used extensively for classifications at the Biotic Group level. This is because 

biological assemblages have not been well characterized for many ecosystems and 

regions, and reporting multiple Biotic Groups as Co-occurring Elements provides a 

flexible tool to consistently characterize the biota that are present within an observational 

unit. As biological assemblages become better characterized and lists of detailed biotope 
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descriptions are developed, the use of Co-occurring Elements to describe multiple Biotic 

Groups at each location should be replaced by identification of a single biotope at each 

location—a single, well-characterized, repeating assemblage that inherently and 

predictably consists of multiple Biotic Groups and Associated Taxa.

10.6.3 Coral Reef Zone

All coral reef environments contain distinct horizontal and vertical zones created by 

differences in depth, morphology, wave and current energy, temperature, and light. The 

following zones are commonly present on shallow and mesophotic reefs (Zitello et al. 

2009).

Table 10.27. Coral Reef Zone Modifier.

Coral Reef Zone

Values Description

Back Reef Area between the seaward edge of a lagoon floor and the 

landward edge of a reef crest. This zone is present only when 

a reef crest exists.

Bank/Shelf Deeper water area (usually > 30 meters) extending offshore 

from the seaward edge of the fore reef (or shoreline) to the 

beginning of the bank/shelf escarpment where the insular 

shelf drops off into deep, oceanic water.

Bank/Shelf Escarpment The edge of the bank/shelf where depth increases rapidly 

into deep oceanic water. This zone begins at approximately 

20–30 meters depth, near the depth limit of features visible 

in aerial images. This zone extends well into depths 

exceeding those that can be seen on aerial photos, and this 

zone is intended to capture the transition from the bank/shelf 

to deep waters of the open ocean.

Fore Reef Area from the seaward edge of the reef crests (which slopes 

into deeper water) to the landward edge of the bank/shelf 

platform. Features not forming an emergent reef crest—but 

still having a seaward-facing slope that is significantly

greater than the slope of the bank/shelf—are also designated 

as forereef.

Lagoon Shallow area (relative to the deeper water of the bank/shelf) 

between the shoreline intertidal zone and a back reef or 

barrier island. This zone is protected from the high-energy 

waves commonly experienced on the bank/shelf and reef 

crest. If no reef crest is present, there is no lagoon zone.
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Coral Reef Zone

Values Description

Reef Crest The flattened, emergent (especially during low tides) or 

nearly emergent segment of a reef. This zone lies between 

the back reef and fore reef zones. In aerial images, breaking 

waves will often be visible at the seaward edge of this zone.

Reef Flat Shallow (semi-exposed) area between the shoreline intertidal 

zone and the reef crest of a fringing reef. This zone is 

protected from the high-energy waves commonly 

experienced on the shelf and reef crest. Reef flat is typically 

not present if there is a lagoon zone.

Ridges and Swales An area of numerous thin, narrow, discontinuous bands of 

coral ridges and leeward sand- and sediment-filled swales. 

Debris and reef-rubble fields behind many of the reefs may 

obscure these margin-parallel seabed features. In Florida, for 

example, this zone extends for an estimated 200 kilometers

along the Florida shelf (from Key Largo to Halfmoon Shoal),

and it is discontinuous due to (a) topography, (b) inconsistent 

responses of coral reefs to changing sea levels, and (c) 

varying effects of the physical environment on reefs and 

sediments.

Shoreline/Intertidal Area between the mean high water line (or the landward 

edge of emergent vegetation—such as Red Mangrove—

when present) and the lowest spring tide level (excluding 

emergent segments of barrier reefs).

Vertical Wall Area with near-vertical slope from the shore to the shelf (or 

shelf escarpment). This zone is typically narrow and may not 

be distinguishable in remotely gathered imagery; however, it

is included because it is recognized as a biologically 

important feature.

10.6.4 Enclosure

Enclosure represents the degree of isolation of a water body from other waters because of 

enclosure by a land mass. In estuaries, enclosure determines the degree of exchange of 

water, materials, energy, and biota between the estuary and the sea. More enclosed water 

bodies have longer water residence times, can tend to be more evaporative and 

hypersaline, and can more readily trap and retain materials within them.
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Table 10.28. Enclosure Modifier.

Enclosure Values Angular Gap

Unenclosed ≥ 150 angular gap from landward end of water body to 

seaward opening; no confining land masses (e.g., islands) 

within or just outside water body.

Partially Enclosed 90 to < 150 angular gap from landward end of water body 

to seaward opening.

Significantly Enclosed 45to < 90 angular gap from landward end of water body 

to seaward opening.

Very Enclosed 10 to < 45 angular gap from landward end of water body 

to seaward opening.

Enclosed Essentially separated from the ocean; waters are completely 

surrounded by land or with a narrow channel connection to 

the sea. This category includes perched estuaries and 

lagoonal estuaries.

Intermittent Class of water bodies that regularly close due to low flow, 

opening seasonally during high flow. Also called ICOLL 

(Intermittently Closed and Open Lake or Lagoon).

10.6.5 Percent Cover Range

To classify a unit to the class and subclass level of the Biotic Component, a user needs to 

know the relative percent cover of each of the components of the substrate. The degree of 

substrate cover for each biotic feature is assessed using the following ranges. These 

categories can also be used as a modifier to describe the density of vegetation (such as 

seagrasses) or other substrate components, and are useful in the Substrate component as 

well. Coarse Percent Cover can be described using one of five coarse descriptors, e.g., 

"Sparse", or, if greater detail is needed, Fine Percent Cover can be described using one of 

eleven range categories, e.g., "10 to < 20%".
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Table 10.29. Percent Cover Modifiers.

Coarse Percent Cover 

Values

Fine Percent Cover 

Values

Trace < 1%

Sparse 1 to < 10%

 (1 to < 30%) 10 to < 20%

20 to < 30 %

Moderate

 

 (30 to < 70%)

30 to < 40 %

40 to < 50 %

50 to < 60 %

60 to < 70 %

Dense

 (70 to < 90%)

70 to < 80 %

80 to < 90%

Complete 90 to 100%

10.6.6 Elevation Profile

The Profile Modifier refers to the elevation of a feature relative to the surrounding level 

of the water or bed.

Table 10.30. Elevation Profile Modifier.

Elevation Profile Values Relative Height (meters)

None 0

Low 0.1 to < 2

Medium 2 to < 5

High ≥ 5

10.6.7 Substrate Layering

Substrate in CMECS conceptually extends to the greatest depth that supports 

multicellular life. Although certain large fauna may penetrate several meters below the 

surface in soft sediments, CMECS generally considers the uppermost 15 centimeters of 
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fine substrates, recognizing that evidence of very-deep burrowing fauna will also be 

present in the top 15 centimeters. The upper 15 centimeters of substrate may present as a 

set of horizontal layers constituting a three-dimensional matrix. A basic identification of 

horizontal substrate layers can be accomplished by describing the characteristics of these 

layers and recording the mean thickness in centimeters together with the ordering of each 

layer below the sediment surface. The process of identifying and describing substrate

layers can provide ecological insights and practical value for users interested in substrate 

structure and process, as well as in ecological history.

The structuring of distinctly layered sediments is captured in CMECS as a modifier using 

any SC classifiers, modifiers, or descriptors in the following format, with measurements 

indicating thickness or depth of the examined layers (as specified). The term “veneer” 

may be used to describe a thin (< 1 centimeter thick) covering of one sediment type over 

another sediment type. Examples:

Modifier: Layering – 4 centimeters (thick) Coarse Sand Layer over > 11 

centimeters (thick) Sandy Silt-Clay Layer

Modifier: Layering – Mud veneer over Cobbles

Modifier: Layering – 2 centimeters (thick) Shell Hash Layer over 6 centimeters

(thick) Sand Layer over > 7 centimeters (thick) Mud Layer

Modifier: Layering – 0 to 5 centimeters (deep) Anthropogenic Woody Debris Layer 

over 5 to > 20 centimeters (deep) Geologic Clay Layer 

Modifier: Layering – Sand Layer over Muddy Sand Layer

More advanced sediment dating techniques, which benefit from special coring equipment 

to recover several meters of sediment, can also provide identification of layers by age in 

years. These more detailed descriptions of layering may require different approaches.

10.7 Temporal Modifiers

10.7.1 Temporal Persistence

The Temporal Persistence Modifier describes the permanency or variability of a 

hydromorphic, geomorphic, or biological feature. Though qualitative and relative, it is 

useful is distinguishing between features that are similar in morphology—but are 

temporally diverse in terms of stability. An example is a mud shoal versus a mudbank;

the former tends to be moved by changing currents or storms, while the latter is more 

stable and persistent.
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Table 10.31. Persistence Modifier. 

Persistence Values

Stochastic

Hours

Days

Weeks

Months

Years

Seasons

Inter-annual

Decades

Centuries 

 
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11. A Spatial-Temporal Framework for CMECS

Components

Each CMECS component encompasses a unique expanse of space and time. As such, 

each component may be arrayed within a relative spatial-temporal context to illustrate its

place within the global marine ecosystem (Figure 11.1). CMECS uses spatial and 

temporal gradients as the basis of the classification standard, because much of what is 

understood about species-environment relationships is structured within a spatialtemporal framework. This framework is intended to provide ecological context for the 

entire classification standard, maximize usability for scientists and managers, and—

eventually—guide habitat data collection and mapping efforts.

Figure 11.1. CMECS Components in a Spatial-Temporal Framework. 

Bounding boxes for units are clipped spatially and temporally (on the bottom left) to 

avoid overlap and confusion between units. See figures below for a more accurate spatialtemporal treatment of each component.
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11.1 Why use a spatial-temporal framework?

The first goal of CMECS is to identify the resources that are present (i.e., “What 

resources are out there?”); however, this document also seeks to frame other ecologically 

important questions (such as “Where are the resources located?” and “How are they 

doing?”) and position CMECS to answer them. In order to address these questions, it 

must be acknowledged that ecosystems are dynamic in space and time. By building a 

spatial-temporal framework into the classification standard, the examination of landscape 

patterns, organization, and change—at multiple spatial and temporal scales—is 

encouraged (Guarinello, Shumchenia, and King 2010).

The CMECS nomenclature serves as a common language for marine ecosystems, and 

adding the spatial-temporal framework makes this nomenclature process oriented. 

Associations and coupling mechanisms among components can be suggested, because the 

framework aligns ecosystem elements on a common scale. Also, structural and functional 

relationships between components can be visualized and form the basis for hypothesis 

testing. Other ecological processes (such as natural and human disturbances, succession, 

invasion, and evolution) can be conceptualized within the same framework and then 

overlaid onto CMECS components, which aids users in understanding which processes 

might be most relevant to particular ecological units (Figure 11.2).

Figure 11.2. The Spatial and Temporal Scale of Ecological Processes (Including 

Natural and Human Disturbances). 
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These processes can be overlain with CMECS units in order to determine which 

processes are most influential at the scales of interest.

11.2 Applications

From a practical standpoint, the spatial-temporal framework puts the ecological unit of 

interest into perspective. Various researchers have shown that the classification does not 

need to be applied in a particular direction; examples can be found in Hewitt et al. (2004)

and Shumchenia and King (2010). Complex ecosystems can be decomposed and 

understood in space and time simultaneously, because spatial and temporal scales are 

often linked (Wu 1999). Spatial and temporal gradients are valuable for evaluating 

ecosystem interactions, and the analysis of ecosystems can be structured to use time, 

spatial replication, or spatial contrast as the basis for experimentation and hypothesistesting (Murawski et al. 2010). The sampling tools and sampling effort necessary to 

capture patterns and processes at a particular scale are related to spatial-temporal 

gradients (Figure 11.3). In this way, the spatial-temporal framework can guide sample 

collection and inform monitoring plans.

Figure 11.3. The Stability of Ecosystem Features as they Relate to Sampling Efforts 

and Strategies are Shown in a Spatial-Temporal Framework.

To capture ecosystem components that are highly spatially and temporally variable, 

sampling effort is high. At broad scales, ecosystem components are in general, larger and 

more stable; therefore sampling effort is relatively low.
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Ecosystem valuation is rapidly becoming an important tool in the ecosystem-based 

management of our oceans (e.g., Derous et al. 2007). Establishing relationships between 

the biology and its physical environment—and then extrapolating those relationships in 

space and time—may be the only practical way to inventory and assess large portions of 

the marine environment. The spatial-temporal framework within CMECS (1) makes these 

relationships explicit and (2) constrains the scales over which these relationships can be 

meaningfully applied. An explicit, quantitative, spatial-temporal framework was recently 

utilized by Wilhelmsson et al. (2010) to assess the magnitude of the impacts from the

construction and operation of renewable energy structures (in the marine environment) on 

a wide range of ecosystem components—from the benthos to hydrology. This approach 

allowed the estimation of cumulative impacts, discussion of mitigation options, and 

identification of knowledge gaps and uncertainties.

Finally, the spatial-temporal framework can serve as a communication tool among 

scientists, managers, and the public; the framework helps convey information about 

ecosystem complexity, variability, available resources, and management goals 

(Guarinello, Shumchenia, and King 2010). The spatial-temporal framework serves as a 

simplified ecosystem model (Thrush and Dayton 2010), which is easily understood by a 

broad range of users.

11.3 CMECS Components in the Spatial-Temporal Framework

11.3.1 Biogeographic and Aquatic Settings

The Biogeographic and Aquatic Settings are the largest-scale units addressed in CMECS

(Figure 11.4). Aside from setting the upper boundaries in space and time for the 

ecosystems under study, the geographic location of these components may speak to the 

ecosystems’ expected spatial-temporal variability. For example, in the coming decades, 

ecosystem variability is expected to increase with latitude due to climate change (Parry et 

al. 2007).
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Figure 11.4. Spatial and Temporal Distribution of Biogeographic and Aquatic 

Settings.

(A) The CMECS Biogeographic and Aquatic Settings exist spatially and temporally 

outside of the bounding scales of the other physical and biological components. (B) The 

System, Subsystem and Ecoregion (within the Biogeographic Setting) provide a general 

setting for more fine-scale CMECS units.

11.3.2 Water Column Component

The Water Column Component encompasses a range of spatial and temporal scales that 

are wider than most other CMECS components (Figure 11.5). The water column is an 

extraordinarily dynamic environment and all observations should be reported in spatial 

and temporal context so as to give order to units that may overlap and grade into one 

another.

The spatial and temporal variability in water column and oceanographic features is the 

primary control on biological pattern over much of the globe. The multi-scale variability 

in oceanographic features influences marine life of all sizes and in all realms. For 

example:

 The relationship between (a) oceanographic features and (b) phytoplankton 

abundance and species composition is relevant to short-term oceanic productivity 

and long-term climate variability (Cermeño et al. 2010). 

 Water column variability affects the regional distribution of benthic organisms 

(Post 2008) and fish recruitment variation (Caselle, Kinlan, and Warner 2010). 

 By classifying water column properties through time, trends in ocean warming 

and acidification can be tracked in order to understand how climate change is 

influencing the distribution of corals (De’ath, Lough, and Fabricius 2009). 
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 Even highly mobile megafauna have been shown to respond to variability in 

oceanographic features. For example, variations in this three-dimensional habitat 

influence the small-scale variability in whale populations (Skov et al. 2008), sea 

birds (Kappes et al. 2010), and Steller sea lions (Lander et al. 2009).

Figure 11.5. Water Column Component Spatial and Temporal Distribution.

(A) The elements of the Water Column Component in a spatial-temporal framework 

showing the hierarchical format. (B) An example classification of Hydroform Classes 

and hydroforms. At fine scales (i.e., the lower left side of the plots) relevant processes 

may occur on very short temporal intervals (diel and sub-diel). At broad scales (i.e., the 

upper right section of the plots), Hydroform Classes such as fronts and currents may help 

describe patterns in global climate.

11.3.3 Geoform Component

Marine geologic processes act on varying time scales and influence features of various 

sizes. For example, at the largest spatial and longest temporal scales, tectonic processes 

influence continental and ocean margins. At geologically intermediate scales of space and 

time, glacial cycles have affected the North American continent and many of the coastal 

geomorphologies that are observed today. On the finest scales addressed by the Geoform 

Component, tidal currents influence the shape and composition of submerged forms on 

sub-kilometer scales and over the course of days (Figure 11.6). 

The Geoform Component consists of a series of spatially and temporally hierarchical 

units. By acknowledging the spatial and temporal scales of influence on Geoform 

Component units, the antecedent and present geologic processes are linked to the spatial 

patterns observed today. Linking process and pattern is an important step in

understanding how environments will respond to different types of geologic forcing, 

biological modification, and/or climate change. Understanding the range of scales 
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relevant to a particular geologic feature will be essential to model—conceptually or 

mathematically—these changes. For example, overlaying Geoform Component units in 

the spatial-temporal framework with units in the Biotic Component will help practitioners 

understand the biotic level at which variability in the geology might influence biological 

patterns. The spatial and temporal variability in geomorphology has been shown to be 

important for mapping regional biodiversity (McArthur et al. 2010), modeling 

tropical/reef habitats (Hamylton and Spencer 2011), predicting fish distributions 

(Kendall, Christensen, and Hillis-Starr 2003; Anderson et al. 2009), and designing marine 

reserve networks (Heyman and Wright 2011).

Figure 11.6. Geoform Component Spatial and Temporal Distribution.

(A) The elements of the Geoform Component shown in a spatial-temporal framework 

with a hierarchical format. (B) A more specific example, which shows the classification 

of a tidal flat within a bay on the East Coast of the United States. At fine scales (i.e., the 

lower left side of the plots) processes such as tides, wind and waves are important in 

influencing the geomorphology of the flat. At broad scales (i.e., the upper right section of 

the plots), the geologic context and stability of the regional geology is established by the 

Tectonic and Physiographic Settings.

11.3.4 Substrate Component

The units within the Substrate Component exist on spatial and temporal scales that are 

narrower than the other CMECS components. The fine-scale, spatial-temporal variability 

of seafloor substrates is key to understanding fine-scale, biological variability, 

characterizing the physical disturbance regime, determining the fate of contaminants, and 

monitoring other anthropogenic impacts (Reid et al. 2005).

Where observations and classifications of substrate begin to exceed the upper limit of the 

spatial and temporal scales of the Substrate Component (Figure 11.7), the Geoform 
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Component may be used to continue the geological classification. Observations of 

substrate that are limited in spatial and/or temporal extent should be classified with the 

Substrate Component, because such observations often cannot be applied or extrapolated 

beyond the initial scale of observation—unless an empirical relationship with another, 

broad-scale environmental factor has been previously established.

Figure 11.7. Substrate Component Spatial and Temporal Distribution.

(A) The elements of the Substrate Component shown in a spatial-temporal framework 

with a narrow spatial-temporal range of units. (B) A more specific example, which shows 

the classification of a gravel/boulder substrate.

11.3.5 Biotic Component

Marine communities vary considerably across spatial and temporal scales. The level of 

variability will affect how people study biotic elements, design experiments and 

monitoring programs, and manages resources. Therefore, it is essential to acknowledge 

this variability when classifying biological data.

The hierarchical elements of the Biotic Component are organized in a spatial-temporal 

framework that makes these concepts explicit (Figure 11.8). At the smallest spatial and 

temporal scales, this component identifies species assemblages and the functional groups 

of marine communities. At these fine scales, biotic interactions (such as competition and 

predation) tend to have the most influence on the distribution and persistence of 

organisms (Menge 1976). At larger scales, biological information classified in the Biotic 

Setting and Biotic Class reflects the physical habitat preferences of the biota. Indeed, it is 

at these scales that physical factors (such as currents, tides, and nutrient availability) exert 

the most influence on biological patterns (Menge 1976; Schoch 1996). By noting a 

biological element’s place in the spatial-temporal framework, practitioners can then 

overlay elements from other components to understand more about species-environment 

relationships in their study area. At the smallest scales, this information can be used to 
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design experiments regarding causal relationships; at the largest scales, the information 

can be used to develop species distribution models and predict biological associations 

(given observed biological-physical linkages).

Figure 11.8. Biotic Component Spatial and Temporal Distribution.

(A) The elements of the Biotic Component shown in a spatial-temporal framework with a

hierarchical format. (B) A more specific example, which shows the classification of a 

Cerianthus community in the spatial-temporal framework. At small scales (i.e., the lower 

left side of the plots), biotic interactions exert direct influences over the distribution and 

persistence of organisms (e.g., competition, predation, grazing, recruitment). At large 

scales (i.e., the upper right section of the plots), physical factors exert indirect influences 

over species occurrence (e.g., geomorphology, currents, wave exposure, food 

availability).

11.3.6 Modifiers

CMECS modifiers provide an additional, and in some cases very specific, 

acknowledgement of the spatial-temporal relevance of an ecological unit. Spatial and/or 

temporal modifiers can be used to avoid over-simplifying dynamic and complex 

environments. For example, sea grass beds may be described with percent cover and 

seasonal occurrence descriptors that can be used to populate spatial and temporal 

modifiers. Modifiers used in this way may aid in conducting very fine-scale ecological 

research comparing sea grass bed growth during different parts of the year, or bed density 

at different locations within the same contiguous bed.

Spatial and temporal modifiers may be essential for CMECS units that encompass wide 

spatial and/or temporal ranges in their generic form. For example, a hydrothermal plume 

(Water Column Component) may persist on timescales ranging from days to decades. A 

temporal persistence modifier for a hydrothermal plume on a dynamic ocean ridge will 

help distinguish it from another plume in a different, less dynamic ridge system. 
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Modifiers used in this way allow CMECS to be simultaneously globally applicable and 

locally relevant.

The use of modifiers to support the spatial-temporal framework of CMECS can 

ultimately lead to addressing broad-ecological assessment and management questions. 

For example, the successional stage modifier, while not explicitly a temporal modifier, 

includes an implicit acknowledgement of recognizable and repeatable changes to marine 

communities. Because patterns in succession are usually predicted with reference to a 

disturbance event, the successional stage modifier can be used as a temporal assessment 

tool. The modifier can indicate a baseline condition by which further changes are marked, 

or can be used to infer recent change over time since a previous unrecorded disturbance 

event.
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12. Applying CMECS in Data Development and Mapping

The settings and components of CMECS represent a way of organizing information to 

describe all the aspects of the coastal and marine environment important to living 

communities. This is unlike many classification systems that selectively focus on features 

detectable through a specific observational method. The component structure of CMECS 

offers enhanced opportunities for environmental analysis, but it also may present 

challenges to those accustomed to developing data using a single technology or for a 

particular purpose. The following section describes important concepts related to this 

mapping and data development: the difference between classification and mapping, how 

CMECS classification approaches traditional mapping issues, the practical relationships 

between the components, and how elements from each component can be integrated and 

visualized to address research questions and management issues. This section is not 

intended to serve as a mapping or modeling protocol; it is provided to give users some 

guidance as they employ CMECS in their own project activities.

12.1 Classification versus Mapping

An ecological classification is not the same as a “map classification.” CMECS is a 

classification of taxonomic concepts—where units are defined based on observations that 

have conceptual thresholds (often the average expression of repeated field observations).

The definitions represent the variation in expression of the unit across its entire range of 

occurrence—not just a local mapping area, and the definitions are not constrained by a 

given observation technology. Map classifications (as portrayed by map legends) are 

often representations of the units that are (a) in a given area at a given time and (b)

detected or practically portrayed with available observation methods and technology and 

resources.

A map of an ecological classification is a spatial representation of the geographic 

distribution, extent, patterns, and variation of the taxonomic concepts (FGDC 2008) in a 

given area. The taxonomic concepts and map legend units may not always have one-toone relationships, because mapping efforts may be constrained by the predetermined map 

scale, available technology, funding, or the study objectives. For example, some 

classification units may form complex mosaics, each smaller than the minimum mapping 

unit. In this case, CMECS allows the user to move upward in the hierarchy, using more 

general units that include multiple constituents as long as they both fall within the same 

higher level category. However, mappers should describe the relationships between the 

map units and CMECS units when they do not have a one-to-one relationship.
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12.2 Spatial Considerations

Spatial heterogeneity is a fundamental characteristic of all landscapes, and describing this 

characteristic accurately is a major challenge in landscape ecology. The degree of 

observed spatial heterogeneity is method dependent because it is determined by the scale 

of observation (Wu et al. 2000). Because of this issue, there is inherent subjectivity in the 

definition of landscape units. However, the placement of areal boundaries has real 

implications for landscape-change studies, habitat inventories, and geostatistical analyses. 

Ecological classification works best if boundaries are placed in a manner such that units 

are homogenous; however, this is often impossible or impractical.

When evaluating mixes, the spatial scale of the variability of the mixture (the “patch 

size”) becomes an important concept. Although a particular organism may be used to 

define classification units or biotopes, it is not uncommon for other distinctive or 

significant organisms (such as larger, mobile predators) to be present in an observational 

or reporting unit. This information may be captured using a Co-occurring Element 

modifier. As with other modifiers, use of this attribute is optional.

Users may also add a descriptor to indicate the quantity of the secondary element within 

an observational unit. CMECS provides a Percent Cover for those situations. See the 

percent cover modifier in Section 10 for categories and values. 

12.3 Temporal Considerations

CMECS recognizes that the seafloor and water column are dynamic; with some units, 

such as coral reefs (persisting for thousands of years) and others such as algal beds

(lasting only for a single season). A given area of seafloor may be may be characterized 

differently over time. Users of CMECS are encouraged to identify all CMECS units 

present during an observation—regardless of their likely longevity. Any CMECS 

observation should be considered a “snapshot in time,” in order to provide the most 

information. When it is important to convey that a community is unlikely to be present 

during follow-up observations, the Temporal Persistence modifier can be used. It is up to 

the user to identify the appropriate time series for observation and data collection so as to

capture important, temporally variable or ephemeral units.

12.4 CMECS and Spatial Data

Information on ecological communities is inherently spatial in nature due to its 

association with a particular place in the landscape. Traditionally, spatial data have been 

organized and represented in four general formats: points, lines, polygons, and grids. 

Although CMECS has been focused on biological communities, CMECS units are very 

amenable to each of the major spatial data types. The following sections provide 

examples of how CMECS units could be represented. They should not be considered a 

required way of attributing or displaying those units.
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12.4.1 Point Data

Point data are ideal for representing in-situ observations taken at discrete locations where 

the area being observed is very small (generally on the order of several meters or less). 

Technologies that typically result in point data are include, grab sampling, coring, plan 

view videography, single-beam acoustics, and quadrat measurements. The following 

example (Figure 12.1) shows grab samples collected in Apalachicola Bay, Florida and 

analyzed for sediment characteristics. Thes data were classified according to the Folk 

system and translates directly into CMECS Substrate Component units. 

Figure 12.1. Sediment Grab Samples: Apalachicola Bay, Florida.

Attributed using CMECS Substrate Component units.
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12.4.2 Line Data

Shoreline character, video transects and laser line scanner data lend themselves to a line 

data format, where information is continuous in one vector. These data support inventory 

purposes and is well suited to analyzing transition zones. The following example (Figure 

12.2) shows a shoreline characterization on the central California coast, organized by GC 

units, which can include additional SC or BC attributes. 

Figure 12.2. Shoreline Characterization.

California coast, showing GC units as segments with Substrate Component attributes.

12.4.3 Polygon Data

A polygon data structure is often used where there is comprehensive information over an 

area. Normally the primary attribute for any polygon is determined by the source data 

such as optical imagery, acoustic backscatter imagery, or bathymetric grids. Often there 

are rule sets for determining the principle attribute and addressing mixed areas. 

Additional attributes or modifiers can be added through field data and ancillary sources. 
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The following example (Figure 12.3) from Redfish Bay, Texas, shows how CMECS units 

can be delineated as discrete polygonal boundaries. 

Figure 12.3. Shallow-water Benthic Habitats in Redfish Bay, Texas.

Image showing simple polygons with attributes from CMECS Biotic and Substrate 

Components.

12.4.4 Grid Data

In a grid data structure information is organized into a matrix of rows and columns with 

individual pixels as the data element, with the size of the pixel being the spatial resolution 

of the data. The same comprehensive source data mentioned in Section 12.4.3 can be 

analyzed to produce a gridded output. This is useful when the boundary of the unit itself 

is less of a concern and map elements grade smoothly into each other. The following 

example (Figure 12.4) shows how satellite derived sea surface temperature imagery can 

be classified at the pixel level to display CMECS WC units. 
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Figure 12.4. MODIS Satellite Image Classified According to CMECS WC Salinity 

Units, Mississippi Delta, Gulf of Mexico.

12.5 Mapping CMECS

Unlike many classification systems, CMECS was not intended to support a particular 

mapping program, which would entail specific scale thresholds, technologies, and 

resolution requirements. Rather, CMECS was envisioned as being usable by technicians 

employing a wide range of observational methods—from in-situ grab sampling, to diveror camera-collected species lists, to regional mapping through satellite remote sensing. 

For this reason, there is no explicit scale requirement or minimum mapping unit 

associated with CMECS. Users are able to define their own mapping requirements based 

on local geographies and project needs, while still taking advantage of the CMECS 

framework.

CMECS components start with general- or landscape-scale units in the upper levels and 

narrow to detailed, fine-scale units at the lowest levels. The appropriate hierarchical level 

of bio-physical description in any component should be determined based on user needs 

and project objectives. To create maps, the complexities of aquatic biology usually need 

to be reduced to a manageable number of meaningful categories—so that polygons can 

be delineated, interpolated, or modeled. For broad-scale mapping with rapid sampling 

tools, the more observational identification to subclass and modifiers (or to biotic group), 
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may be well suited to project objectives. While a full attribution of any observation is 

desirable, users are not required to make determinations at levels below which they can 

reliably observe (or speculate about the larger context of an observation), if this is not 

practical. Users can apply units from multiple levels or components as their technology, 

sampling density, and ancillary data will allow. There is no requirement to report on units 

for which an observation cannot be made.

In addition to employing units throughout the components as needed, users are 

encouraged to apply CMECS modifiers in developing their maps. These descriptors can 

add information to previously delineated polygons—or they can be used to subdivide the 

polygons. In some cases, users may want to include modifier units as actual mapping 

categories along with other component units in a map, or they can be used as standalone 

maps for a single modifier (such as rugosity or slope). Modifiers may be used when 

information allows, but their use is not required. 

The list of CMECS modifiers has been developed based on a wide range of potential 

information needs and data types. However, users are free to apply additional modifiers 

based on their own project needs. An example of this might be in further characterizing 

intertidal oyster reefs. In addition to the CMECS modifier Percent Cover, South Carolina

resource managers commonly use their own modifier, Strata, which is an assessment of 

the amount and posture of live shell on a reef (South Carolina Department of Natural 

Resources 2008). Users who apply their own modifiers should ensure that they do not 

overlap (or conflict) with existing CMECS units. It is also important that users define 

those modifiers and describe their use to allow others to take advantage of the additional 

information.

12.6 Integrating the Components

12.6.1 Building Derived CMECS Units

CMECS units are the basic building blocks that can be used to define and describe 

ecological units at many scales. Units from any component, subcomponent, and level of 

the hierarchy can be combined to define new units based on user needs. For example, a 

user interested in developing global scale biological units for conservation assessment 

might find that the biotic group is too broad for their needs, but the biotic community too 

fine to apply practically at a global scale. These users might consider defining new units 

by subdividing the BC biotic groups by BS provinces (e.g., Warm Temperate Northwest 

Atlantic Seagrass Beds and Tropical Northwestern Atlantic Seagrass Beds Seagrass 

Bed). If derived based on known patterns of biodiversity, these new units would allow the 

user to describe more detailed units without having to know the specifics of global 

distribution of seagrass biological communities. It is the responsibility of the user to 

ensure that the units they create represent the ecological meaning they intend to describe.
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12.6.2 Integrating Units in Mapping

The individual components of CMECS commonly overlap in space and time, and they 

can be considered as layers in a traditional Geographic Information System (GIS). 

Mappers have the option of developing a comprehensive map for each component for 

their study area, or they may map selected units from various components to assemble a 

single “flat” map. The elements in this type of map may be based strictly on the 

capabilities of the observational technology—for example, those units detectable through 

aerial photography or those related to the specific habitat requirements of a species of 

interest. A map based on aerial photography will only contain information on the largescale “cover” of intertidal and shallow subtidal areas. Conversely, a map designed to 

show rockfish habitat might focus on specific substrate types, geoforms, depth zones, and 

water conditions; obtaining data for that map would require multiple technologies.

The decision to integrate components into one map—or to create separate component 

maps—should be based on the information needs of the project, type of source data, 

project logistical constraints, and spatial exclusivity between those units being integrated 

in the map. For example, in cases where boundaries between component units (such as 

between SC substrates and BC biotic groups) are very different, then it may be advisable 

to first generate separate data layers for each component, and then later integrate them in 

a GIS environment for analysis (in order to avoid an overly complex single dataset).

Figure 12.5 illustrates how elements from various CMECS components could be 

assembled into a single, flat spatial dataset. In this case, the source data technology is an 

aerial optical instrument with 0.5-meter pixel size and a minimum mapping unit of 10x10

meters. The map includes the CMECS units that (a) can be detected using this technology 

and (b) are of concern for this mapping project. This approach may be preferred where 

the units are generally spatially exclusive (that is, boundaries between units from one 

component generally agree with those of another) and where a single technology is being 

employed.
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Figure 12.5. Benthic Habitat Map for Arcata Bay, California.

This flat map includes units from two CMECS components and employs a percent cover 

modifier.

The following three figures illustrate the maps that would result from creating separate 

feature layers for each component. Despite being topologically separate data, they can be 

integrated as feature classes within a geodatabase data structure. This approach may be 

preferable where (a) wall-to-wall information is desired for each component and (b) there 

is minimal spatial exclusivity between components (that is, landscape units [polygons] in 

one component tend to cross borders in the other components).

Independent-component maps will often have multiple, unclassified areas in which 

information on a component is unavailable. These are in contrast with “null” areas where 

no observation was attempted or possible. Unclassified areas may be the result of several 

factors, including insufficient resolution to detect units for that component (for example,

epifaunal or infaunal biota in the unconsolidated substrate areas) and an inability to use a 

given component unit as a reliable proxy for a unit in another component. An example of 

a successful proxy is the presence of eelgrass as a proxy for unconsolidated substrate 

based on the strong association between the two. Finally, unclassified areas can be due to 

fundamental limitations of the technology, in this case aerial optical imagery which 

cannot penetrate the submerged portions of the scene sufficiently to provide information 

on the benthos. Mappers taking the multi-layer approach should provide documentation 

on the cause of unclassified areas in their data so that users do not make erroneous 

assumptions about what may or may not be present in those areas.
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Figure 12.6. Biotic Component Map for Arcata Bay, California.

Unclassified areas in this map include water and intertidal mudflats with insufficient 

biologic signatures to assign a BC attribute.

Figure 12.7. Substrate Component Map for Arcata Bay, California.

In this map, unconsolidated substrate is assumed beneath the seagrass beds—but cannot 

be assumed beneath the algal beds, because these can also occur on hard substrate.
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Figure 12.8. Geoform Component Map for Arcata Bay, California.

The geoform map does not have unclassified areas, because all of the features produce 

signatures detectable at this scale—and the presence of overlying biota does not hamper 

identification. For this reason, geoform maps can be a useful bounding framework for the 

BC and SC data.

Regardless of how the component information is initially captured and organized, GIS 

analysis will be facilitated by creating separate feature layers for each component. The 

ESRI geodatabase structure allows multiple layers (component maps) to be queried and 

visualized according to criteria determined by the user. It also allows rule-sets to be 

established governing the relationships and analysis weights associated with different, 

spatially overlapping data. 

12.7 Sharing CMECS Data

Because CMECS users are free to define so many fundamental aspects of data 

development based on their own needs, assembling a regional perspective from separate 

mapping activities could present a challenge. An approach that allows CMECS units first 

to be used and applied at the local level and then later to be translated upward to compile 

a regional assessment will maximize the (1) potential user base and (2) number of 

management issues that could be addressed using any individual dataset. This can be 

accomplished through the effective use of FGDC-compliant metadata with attention to a 

number of data elements. In addition to spatial location, the metadata elements important 

to CMECS integration are:

 Minimum Mapping Unit
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 CMECS units used

 Date/Time and duration of the study (to address temporal issues)

 Ancillary data used to support the analysis (e.g., a bathymetric grid used to 

determine tidal zones)

 Resolution/Sampling density of the source data

Ideally, users will decide to use the CMECS system at the outset of any project. 

However, many groups have already developed trend information based on an existing 

classification, and there may be management imperatives that make adopting CMECS 

impractical. In those cases, a crosswalk from an existing system into CMECS is the best 

way to preserve local relevance and also support regional assessment. It is important to 

note that successful crosswalking is dependent on an understanding of the parameters 

behind the original data development and equivalency between classification systems—

not only at the unit definition level, but also in hierarchical context. Appendix H presents 

guidance on how to accomplish and document crosswalks between data.
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13. Dynamic Content within the CMECS Standard

As CMECS use increases, there will be a need to add information to the standard. 

Continued research is likely to discover new ecosystem features, habitats, biotic 

communities, or biotopes. Similarly, appreciation of the functioning, roles, and 

importance of ecosystem components may require the redefinition or expansion of units 

recognized by CMECS. To accommodate the dynamic nature of the science underlying 

CMECS, the standard includes a mechanism to augment (or revise) ecological units.

New ecological units shall be introduced through a peer-review process. An authoritative 

process is necessary to maintain the consistency, credibility, orderly change, and rigor of 

the classification. Peer review of proposals for new units—as well as for changes 

proposed to component concepts—is essential to the long-term utility and progressive 

development of CMECS. The peer process requires that those proposing new units make 

a convincing case based on a clear explanation of the data, methods, and results. In order 

for a comprehensive classification of coastal and marine ecological units for the United 

States to be viable, it must include peer review of proposed units as an integral part.

A CMECS team will follow detailed protocols for provisional and final acceptance of 

new units. These will be modeled on the protocols for updates to the National Vegetation 

Classification Standard, FGDC-STD-005-2008 (FGDC 2008) and from procedures 

outlined in the Marine Habitat Classification for Britain and Ireland, Version 04.05 

(Connor et al. 2004).

13.1 Revising CMECS

A CMECS Peer-Review Panel shall be established to evaluate proposed revisions to the 

standard. Specific operational procedures shall be developed and announced by the Panel

after its establishment. The Panel shall include one or more subgroups to deal with issues 

relating to CMECS settings and components. Additional subgroups may be constituted to 

deal with other technical matters, should the need arise.

13.2 Peer-Review Process

a. The objectives of the peer-review process are to:

i. Ensure compliance with classification nomenclature and documentation 

standards;

ii. Maintain reliability of data and documentation for ecosystem units and

biotic communities data;

iii. Eliminate conflicts with existing or proposed CMECS units; and

iv. Minimize conflict or ambiguity with other classifications.
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b. The CMECS Peer-Review Panel (the “Panel”) is responsible for ensuring that criteria 

specified in the standard are followed. The Panel shall adhere to the guiding 

principles of CMECS, and they shall ensure the good order and scientific credibility 

of the classification.

c. The overall peer-review process shall be administered by the Panel (authorized and 

overseen by the lead agency, the National Oceanic and Atmospheric Administration 

[NOAA]).

i. NOAA shall be the lead agency for administering the process of reviewing ecosystem

units; and

ii. NOAA may delegate lead responsibility for specific sub-units to other federal 

agencies that have specific expertise in relevant disciples.

d. The Panel may structure a peer review process that varies among the various elements 

of the standard and/or among peer review subgroups. Tailored processes may be 

needed to address issues intrinsic to the science and practice associated with 

individual elements. Similarly, procedures for peer review subgroups may be 

customized to reflect the matters under consideration.

e. Investigators wishing to contribute to CMECS by proposing changes to the 

classification shall submit proposals for new (or revised) units to the Panel. The Panel

(or its subgroups) shall issue specific directions, including requirements for proposed 

candidate additions and alterations to the standard. This may include a requirement to 

use a prescribed template.

f. The Panel shall maintain a publicly available account of official actions, which shall 

include official changes to the list of CMECS units and supporting information for 

those changes. The Panel shall issue separate guidance on the operation and 

maintenance of the public account of official actions. 

g. The peer-review process shall be completed within a reasonable time frame (to be 

specified by the Panel) and it shall balance potentially conflicting needs for CMECS 

technical enhancement and CMECS stability.

h. A comprehensive, publically available list of CMECS units will be on a website 

hosted by the sponsoring agency (NOAA) or its designee. The list shall be maintained 

and updated regularly; it shall include explicit dates and versioning information.
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14. Literature Cited

Abell, R., M. Thieme, C. Revenga, M. Bryer, M. Kottelat, N. Bogutskaya, B. Coad, et al. 

2008. “Freshwater Ecoregions of the World: A New Map of Biogeographic Units 

for Freshwater Biodiversity Conservation.” BioScience 58 (5): 403–414.

Allee, R. J., M. Dethier, D. Brown, L. Deegan, G. R. Ford, T. R. Hourigan, J. Maragos, et 

al. 2000. Marine and Estuarine Ecosystem and Habitat Classification. National 

Oceanic and Atmospheric Administration technical memorandum. NMFS-F/SPO43. National Oceanic and Atmospheric Administration.

Anderson, T. J., Syms, C., Roberts, D. A., Howard, D. F. 2009. “Multi-Scale Fish–

Habitat Associations and the Use of Habitat Surrogates to Predict the Organisation 

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Table A1 Biogeographic Setting, United States Subset (Spalding et al. 2007). Realm, Province, and Ecoregion

Realm Province Ecoregion

Arctic Arctic (no provinces identified) Beaufort Sea Continental Coast and Shelf

Chukchi Sea

Eastern Bering Sea

Temperate Northern Atlantic Cold Temperate Northwest Atlantic Scotian Shelf

Gulf of Maine/Bay of Fundy

Virginian

Warm Temperate Northwest Atlantic Carolinian

Northern Gulf of Mexico

Temperate Northern Pacific Cold Temperate Northeast Pacific Aleutian Islands

Gulf of Alaska

North American Pacific Fijordland

Puget Trough/Georgia Basin

Oregon, Washington, Vancouver Coast and Shelf

Northern California

Southern California Bight

Tropical Atlantic Tropical Northwestern Atlantic Eastern Caribbean

Greater Antilles

Southwestern Caribbean

Floridian

Central Indo-Pacific Tropical Northwestern Pacific Mariana Islands

Eastern Indo-Pacific Hawaii Hawaii

Marshall, Gilbert and Ellis Islands Marshall Islands

Central Polynesia Line Islands

Phoenix/Tokelau/Northern Cook Islands

Samoa Islands
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Appendix B (Normative): CMECS Aquatic Setting 
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Table B1 Aquatic Setting: System, Subsystem, and Tidal Zone.

System Subsystem Tidal Zone

Lacustrine Littoral

Limnetic

Estuarine Coastal Supratidal Zone

Intertidal Zone

Subtidal Zone

Open Water Subtidal Zone

Tidal Riverine Coastal Subtidal Zone

Intertidal Zone

Tidal Riverine Open Water Subtidal Zone

Marine Nearshore Supratidal Zone

Intertidal Zone

Subtidal Zone

Offshore Subtidal Zone

Oceanic Subtidal Zone
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Appendix C (Normative): CMECS Water Column Component
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Table C1 Water Column Component: Layer, Salinity and Temperature Regimes, Hydroform Class, Hydroform Type, and Biogeochemical Feature.

Water Column Layer Salinity Regime Temperature Regime

Hydroform 

Class Hydroform Hydroform Type

Biogeochemical 

Feature

Estuarine Coastal Surface Layer Oligohaline Water Frozen/Superchilled Water Current Boundary Current Eastern Boundary Current Benthic Boundary Layer

Estuarine Coastal Upper Water Column Mesohaline Water Very Cold Water Western Boundary Current Boundary Layer

Estuarine Coastal Pycnocline Lower Polyhaline Water Cold Water Buoyancy Flow Downwelling Chlorophyll Maximum

Estuarine Coastal Lower Water Column Upper Polyhaline Water Cool Water Upwelling Chlorophyll Minimum

Estuarine Open Water Surface Layer Euhaline Water Moderate Water Current Meander Drifting Fine Woody Debris

Estuarine Open Water Upper Water Column Hyperhaline Water Warm Water Deep Boundary Current Drifting Herbaceous Debris

Estuarine Open Water Pycnocline Very Warm Water Deep Circulation Abyssal Deep Circulation Drifting Trees

Estuarine Open Water Lower Water Column Hot Water Abyssal Deep Circulation Drifting Woody Debris

Estuarine Tidal Riverine Coastal Surface Layer Very Hot Water Bathyl Deep Circulation Euphotic Zone

Estuarine Tidal Riverine Coastal Upper Water Column Deep Convection Halocline

Estuarine Tidal Riverine Coastal Pycnocline Density Flow Lens

Estuarine Tidal Riverine Coastal Lower Water Column Ekman Flow Ekman Upwelling Lysocline

Estuarine Tidal Riverine Open Water Surface Layer Ekman Downwelling Marine Snow Aggregation

Estuarine Tidal Riverine Open Water Upper Water Column Inertial Current Microlayer

Estuarine Tidal Riverine Open Water Pycnocline Langmuir Circulation Nepheloid Layer

Estuarine Tidal Riverine Open Water Lower Water Column Mean Surface Current North Equatorial Surface Current Neustonic Layer

Marine Nearshore Surface Layer South Equatorial Surface Current Nutrient Maximum

Marine Nearshore Upper Water Column Mesoscale Eddy Cold Core Ring Nutrient Minimum

Marine Nearshore Pycnocline Warm Core Ring Nutricline

Marine Nearshore Lower Water Column Residual Current Fjord Circulation Oxygen Maximum

Marine Offshore Surface Layer Partially Mixed Domain Oxygen Minimum

Marine Offshore Upper Water Column Reverse Estuarine Flow Oxycline

Marine Offshore Pycnocline Salt Wedge Domain Sea Foam

Marine Offshore Lower Water Column Well-mixed Domain Seep

Marine Oceanic Surface Layer Sub-mesoscale Eddy Surface Film

Marine Oceanic Epipelagic Upper Layer Thermohaline Eddy Surface Mixed Layer

Marine Oceanic Epipelagic Pycnocline Tidal Flow Diurnal Tidal Flow Thermocline

Marine Oceanic Epipelagic Lower Layer Mixed Semi-diurnal Tidal Flow Turbidity Maximum

Marine Oceanic Mesopelagic Layer Semi-diurnal Tidal Flow

Marine Oceanic Bathypelagic Layer Turbidity Flow

Marine Oceanic Abyssopelagic Layer Wave-driven Current Longshore Current

Marine Oceanic Hadalpelagic Layer Rip Current

Undertow

Wind-driven Current
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Table C1 Water Column Component (Continued).

Water Column Layer Salinity Regime Temperature Regime

Hydroform 

Class Hydroform Hydroform Type

Biogeochemical 

Feature

Front Coastal Upwelling Front

Shelf-break Front

Tidal Front

Water Mass Background Mesoscale Field

Fumarole Plume

Hydrothermal Plume Detached Hydrothermal Plume

Ice Drift Ice

Fast Ice

Frazil or Grease Ice

Ice Field

Ice Floe

Pack Ice

Pancake Ice

Polnya

Mesoscale Lens River/Estuary Plume

Meddy

Microscale Lens Small Freshwater Plume

Winter Water Mass

Wave Anthropogenic Wave

Coastally Trapped Wave Internal Kelvin Wave

External Kelvin Wave

Shelf Wave

Topographic Wave

Edge Wave

Equatorial Wave

Non-Equatorial Wave

Internal Wave

Seiche

Storm Surge

Surf Zone

Surface Wave

Surface Wind Wave

Surface Swell

Tsunami
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Table D1 Geoform Component: Tectonic and Physiographic Settings, Geoform Origin, Geoform and Geoform Types.

Tectonic Setting Physiographic Setting 

Geoform

Origin Geoform Level 1 Level 2 Geoform Type Level 1 Level 2

Abyssal Plain Abyssal/Submarine Fan Geologic Apron x

Convergent Active Continental Margin Barrier Reef Bank x

Divergent Active Continental Margin Bight Bar x x Bay Mouth Bar x

Fracture Zone Borderland Longshore Bar x

Spreading Center Continental/Island Rise Point Bar x

Mid-Ocean Ridge Continental/Island Shelf Relict Longshore Bar x

Passive Continental Margin Continental/Island Shore Complex Basin x

Transform Continental Margin Continental/Island Slope Beach x x Barrier Beach x x

Tectonic Trench Embayment/Bay Mainland Beach x x

Fjord Pocket Beach x

Inland/Enclosed Sea Tide-Modified Beach x x

Lagoonal Estuary Tide-Dominated Beach x x

Major River Delta Wave-Dominated Beach x x

Marine Basin Floor Beach Berm x x

Ocean Bank/Plateau Boulder Field x

Riverine Estuary Cave x

Shelf Basin Channel x x Pass/Lagoon Channel x

Shelf Break Sand Channel x

Sound Slough x

Submarine Canyon Tidal Channel/Creek x x

Trench Cone x x

Cove x x Barrier Cove x x

Mainland Cove x x

Delta x x Glacial (Kame) Delta x

Ebb Tidal Delta x

Flood Tidal Delta x

Flood Tidal Delta Slope x

Levee Delta x x

Delta Plain x

Depression x Scour Depression x

Diapir x x Salt Dome x x

Dike x

Drumlin x
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Table D1 Geoform Component (Continued).

Tectonic Setting Physiographic Setting 

Geoform

Origin Geoform Level 1 Level 2 Geoform Type Level 1 Level 2

Geologic Drumlin Field x

Dune Field x

Dune x

Fan x x Alluvial Fan x

Basin Floor Fan x

Shoreline Fan x

Washover Fan x x

Flat x x Back Barrier Flat x

Barrier Flat x

Ebb Tidal Delta Flat x

Flood Tidal Delta Flat x

Tidal Flat x x

Washover Fan Flat x

Wind Tidal Flat x

Fluvio-Marine Deposit x x

Fracture x x

Hole/Pit x Scour Hole x

Solution Hole/Pit x

Hydrothermal Vent Field x x

Hydrothermal Vent x

Inlet x x Tidal Inlet x

Relict Tidal Inlet x

Island x x Barrier Island x x

Karren x

Knob x

Lagoon x x

Lava Field/Plain x

Ledge x x

Marine Lake x

Marsh Platform x x

Megaripples x
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Table D1 Geoform Component (Continued).

Tectonic Setting Physiographic Setting 

Geoform

Origin Geoform Level 1 Level 2 Geoform Type Level 1 Level 2

Geologic Moraine x Disintegration Moraine x

End Moraine x

Ground Moraine x

Kame Moraine x

Lateral Moraine x

Recessional Moraine x

Terminal Moraine x

Mound/Hummock x x Tar Mound x

Mud Volcano x

Natural Levee x Lava Levee x

Overhang (Cliff) x x

Panne x

Pavement Area x x

Platform x x Wave-Cut Platform x

Pockmark Field x

Pockmark x

Ridge x x Beach Ridge x x

Esker x x

Ripples x

Rock Outcrop x x Authigenic Carbonate Outcrop x

Rubble Field x

Runnel/Rill x

Sediment Wave Field x x

Scarp/Wall x x Fault Scarp x x

Erosion Scarp x x

Beach Scarp x x

Scar x x Iceberg Scour Scar/Furrow x x

Slump Scar x x

Seamount x Guyot x

Knoll Seamount x

Pinnacle Seamount x

Sediment Sheet x
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Table D1 Geoform Component (Continued).

Tectonic Setting Physiographic Setting 

Geoform

Origin Geoform Level 1 Level 2 Geoform Type Level 1 Level 2

Geologic Shelf Valley x

Shoal x x Moraine Shoal x x

Shore Complex x

Shore x x Foreshore x x

Backshore x x

Slope x x Washover Fan Slope x

Spit x

Stack x

Submarine Slide Deposit x

Swale/Slack x

Terrace x Fluviomarine Terrace x

Wave-Built Terrace x

Marine Terrace x

Tidepool x

Till Surface x x

Tombolo x

Biogenic Atoll x Submerged Atoll/Atoll Reef x

Burrows/Bioturbation x Tilefish Burrow x

Coral Reef Island x x

Mollusk Reef x x Fringing Mollusk Reef x

Linear Mollusk Reef x

Patch Mollusk Reef x

Washed Shell Mound x

Deep/Cold-Water Coral Reef x x Biogenic Deep Coral Reef x x

Deep Coral Carbonate Mound x x

Shallow/Mesophotic Coral Reef x x Aggregate Coral Reef x x

Shallow/Mesophotic Coral Carbonate Moundx x

Coral Head/Bomme x

Coral Pinnacle x

Fragile Mesophotic Coral Reef x x

Fringing Coral Reef x x

Halo x x
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Table D1 Geoform Component (Continued).

Tectonic Setting Physiographic Setting 

Geoform

Origin Geoform Level 1 Level 2 Geoform Type Level 1 Level 2

Biogenic Linear Coral Reef x x

Patch Coral Reef x x

Pinnacle Coral Reef x x

Spur and Groove Coral Reef x x

Tree Fall x

Whale Fall x

Worm Reef x Patch Worm Reef x

Linear Worm Reef x

Anthropogenic Aquaculture Structure x x

Artificial Bar x Harbor Bar x

Artificial Dike x Artificial Levee x

Artificial Reef x

Artificial Scar x Prop Scar x

Trawling Scar x

Buoy x

Breakwater/Jetty x Groin x

Breachway x

Bulkhead x

Cable Area x

Cable x

Canal x x

Dam x x

Dock/Pier x

Dredged/Excavated Channel x x

Dredge Deposit x x Dredge Deposit Shoal x x

Dredge Deposit Bank x x

Dredge Disturbance x

Drilling (Oil and Gas) Rig x

Fill Area x Landfill x

Fish Pond x

Harbor x
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Table D1 Geoform Component (Continued).

Tectonic Setting Physiographic Setting 

Geoform

Origin Geoform Level 1 Level 2 Geoform Type Level 1 Level 2

Anthropogenic Lock x

Lost/Discarded Fishing Gear x

Marina/Boat Ramp x

Mooring Field x

Mosquito Ditch x

Outfall/Intake x

Pilings x

Pipeline Area x

Rip Rap Deposit x

Salt Pond Complex x

Salt Pond x

Seawall x

Tidal/Wave Energy Structure x

Trash Aggregation x x

Wharf x

Wind Energy Structure x

Wreck x
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Appendix E (Normative): CMECS Substrate Component
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Table E1 Substrate Component: Substrate Origin, Substrate Class, Substrate Subclass, Substrate Group, and Substrate Subgroup.

Substrate Origin Substrate Class Substrate Subclass Substrate Group Substrate SubGroup

Geologic Substrate Rock Substrate Bedrock

Megaclast

Unconsolidated Mineral Substrate Coarse Unconsolidated Substrate Gravel Boulder

Cobble

Pebble

Granule

Gravel Mixes Sandy Gravel

Muddy Sandy Gravel

Muddy Gravel

Gravelly Gravelly Sand

Gravelly Muddy Sand

Gravelly Mud

Fine Unconsolidated Substrate Slightly Gravelly Slightly Gravelly Sand

Slightly Gravelly Muddy Sand

Slightly Gravelly Sandy Mud

Slightly Gravelly Mud

Sand Very Coarse Sand

Coarse Sand

Medium Sand

Fine Sand

Very Fine Sand

Muddy Sand Silty Sand

Silty-Clayey Sand

Clayey Sand

Sandy Mud Sandy Silt

Sandy Silt-Clay

Sandy Clay
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Table E1 Substrate Component (Continued).

Substrate Origin Substrate Class Substrate Subclass Substrate Group Substrate SubGroup

Geologic Substrate Unconsolidated Mineral Substrate Fine Unconsolidated Substrate Mud Silt

Silt-Clay

Clay

Biogenic Substrate Algal Substrate Algal Sand Halimeda Sand

Rhodolith Substrate Rhodolith Rubble

Rhodolith Hash

Rhodolith Sand

Coral Substrate Coral Reef Substrate

Coral Rubble

Coral Hash

Coral Sand

Organic Substrate Organic Debris Peat Debris

Woody Debris Fine Woody Debris

Coarse Woody Debris

Very Coarse Woody Debris

Organic Detritus

Organic Mud

Ooze Substrate Carbonate Ooze Coccolithophore Ooze

Foraminiferan Ooze Globigerina Ooze

Pteropod Ooze

Siliceous Ooze Diatomaceous Ooze

Radiolarian Ooze

Shell Substrate Shell Reef Substrate Clam Reef Substrate Coquina Reef Substrate

Crepidula Reef Substrate

Mussel Reef Substrate

Oyster Reef Substrate
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Table E1 Substrate Component (Continued).

Substrate Origin Substrate Class Substrate Subclass Substrate Group Substrate SubGroup

Biogenic Substrate Shell Substrate Shell Rubble Clam Rubble Coquina Rubble

Crepidula Rubble

Mussel Rubble

Oyster Rubble

Shell Hash Clam Hash Coquina Hash

Crepidula Hash

Mussel Hash

Oyster Hash

Shell Sand Coquina Sand

Worm Substrate Sabellariid Substrate Sabellariid Reef Substrate

Sabellariid Rubble

Sabellariid Hash

Serpulid Substrate Serpulid Reef Substrate

Serpulid Rubble

Serpulid Hash

Anthropogenic Substrate Anthropogenic Rock Anthropogenic Rock Reef Substrate

Anthropogenic Rock Rubble

Anthropogenic Rock Hash

Anthropogenic Rock Sand

Anthropogenic Rock Mud

Anthropogenic Wood Anthropogenic Wood Reef Substrate

Anthropogenic Wood Rubble

Anthropogenic Wood Hash
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Table E1 Substrate Component (Continued).

Substrate Origin Substrate Class Substrate Subclass Substrate Group Substrate SubGroup

Anthropogenic Substrate Construction Materials Construction Reef

Construction Rubble

Construction Hash

Metal Metal Reef Substrate

Metal Rubble

Metal Hash

Trash Trash Rubble

Trash Bits
Federal Geographic Data Committee FGDC-STD-018-2012

Coastal and Marine Ecological Classification Standard, June 2012

Appendix E (Normative): CMECS Substrate Component

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Appendix F (Normative): CMECS Biotic Component

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Appendix F (Normative): CMECS Biotic Component
Federal Geographic Data Committee FGDC-STD-018-2012

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Table F1 Biotic Component: Biotic Setting, Biotic Class, Biotic Subclass, Biotic Group, Biotic Community

Biotic Setting Biotic Class Biotic Subclass Biotic Group Biotic Community

Planktonic Biota Zooplankton Crustacean Holoplankton Amphipod Aggregation Hyperia Aggregation

Caprellid Aggregation

Copepod Aggregation Acartia Aggregation

Calanus Aggregation

Krill Aggregation Euphausia Aggregation

Thysanoessa Aggregation

Crustacean Meroplankton Decapod Larval Aggregation Brachyuran Crab Larval Aggregation

Anomuran Crab Larval Aggregation

Pandalus Larval Aggregation

Mixed Crustacean Larvae

Coral Meroplankton Coral Spawning and Larval Aggregation Acroporid Spawning Aggregation

Montastraea Spawning Aggregation

Coral Larval Aggregation Acroporid Larval Aggregation

Monstastraea Larval Aggregation

Echinoderm Meroplankton Mixed Echinoderm Larval Aggregation Ophiuroid Larval Aggregation

Asteroidean Larval Aggregation

Holothurian Larval Aggregation 

Fish Meroplankton Fish Spawning and Larval Aggregation Damselfish Spawing and Larval Aggregation

Grouper Spawning and Larval Aggregation

Surgeonfish Spawning and Larval Aggregation 

Fish Larval Aggregation Clupeid Larval Aggregation 

Engraulid Larval Aggregation

Sciaenid Larval Aggregation

Gelatinous Zooplankton Ctenophore Aggregation Beroe Aggregation

Mnemiopsis Aggregation

Pleurobrachia Aggregation

Jellyfish Aggregation Aurelia Aggregation

Chrysaora Aggregation
Federal Geographic Data Committee FGDC-STD-018-2012

Coastal and Marine Ecological Classification Standard, June 2012

Appendix F (Normative): CMECS Biotic Component

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Table F1 Biotic Component (Continued).

Biotic Setting Biotic Class Biotic Subclass Biotic Group Biotic Community

Planktonic Biota Zooplankton Gelatinous Zooplankton Salp Aggregation Thalia Aggregation

Pegia Aggregation

Siphonophore Aggregation Bargmannia Aggregation

Nanomia Aggregation

Physalia Aggregation 

Mixed Zooplankton Mixed Zooplankton Aggregation Chaetognath, Salp, and Fish Larval Aggregation

Ctenophore, Worm and Copepod Aggregation

Molluscan Holoplankton Pteropod Aggregation Carolla Aggregation

Clione Aggregation 

Molluscan Meroplankton Veliger Aggregation Bivalve Veliger Aggregation

Gastropod Veliger Aggregation

Protozoan Holoplankton Foraminiferan Aggregation Globigerina Aggregation Layer

Radiolarian Aggregation Acantharea Aggregation

Polycistina A ggregation

Worm Holoplankton Chaetognath Aggregation Flaccisagitta Aggregation 

Sagitta Aggregation

Polychaete Aggregation Syllid Aggregation

Tomopteris Aggregation

Worm Meroplankton Larval Worm Spawning Aggregation Neanthes Spawning Aggregation

Nereid Spawning Aggregation

Palolo (Eunice ) Spawning Aggregation

Larval Worm Aggregation Nereid Larval Aggregation

Nemeretean Larval Aggregation

Polychaete Larval Aggregation

Floating/Suspended Plants 

and Macroalgae

Floating/Suspended 

Macroalgae

Algal Rafts Gracilaria Rafts

Kelp Rafts 

Rockweed Rafts 

Sargassum Rafts

Ulva Rafts 
Federal Geographic Data Committee FGDC-STD-018-2012

Coastal and Marine Ecological Classification Standard, June 2012

Appendix F (Normative): CMECS Biotic Component

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Table F1 Biotic Component (Continued).

Biotic Setting Biotic Class Biotic Subclass Biotic Group Biotic Community

Planktonic Biota Floating/Suspended Plants 

and Macroalgae

Floating/Suspended 

Macroalgae

Algal Particles Gracilaria Particles

Kelp Particles

Rockweed Particles

Sargassum Particles

Ulva Particles

Floating/Suspended Vascular 

Vegetation

Floating/Suspended Freshwater and 

Brackish Vegetation

Eichornia Mats

Pistia Mats

Phytoplankton Chlorophyte Phytoplankton Chlorophyte Aggregation Chlorella Aggregation

Chlorophyte Bloom Pyramimonas Bloom

Chlorophyte Maximum Layer Ostreococcus Maximum Layer

Chrysophyte Phytoplankton Chrysophyte Aggregation Apindella Aggregation

Chrysophyte Bloom Aureococcus Bloom

Chrysophyte Maximum Layer Dinobryon maximum Layer

Coccolithophore 

Phytoplankton

Coccolithophore Aggregation Coccolithus pelagicus Aggregation

Coccolithophore Bloom Emiliania huxleyi Bloom

Coccolithophore Maximum Layer Crenalithus Maximum Layer

Cryptophyte Phytoplankton Cryptophyte Aggregation Chrysophaeum Aggregation

Cryptophyte Bloom Myrionecta Bloom

Cryptophyte Maximum Layer Teleaulax Maximum Layer

Cyanophyte Phytoplankton Cyanophyte Aggregation Nodularia Aggregation

Cyanophyte Bloom Synechococcus Bloom

Cyanophyte Maximum Layer Trichodesmium Maximum layer

Diatom Phytoplankton Diatom Aggregation Thalassiosira Aggregation

Diatom Bloom Skeletonema Bloom

Diatom Maximum Layer Asterionellopsis Maximum Layer

Dinoflagellate Phytoplankton Dinoflagellate Aggregation Noctiluca Aggregation

Dinoflagellate Bloom Karenia Bloom

Dinoflagellate Maximum Layer Gymnodinium Maximum Layer
Federal Geographic Data Committee FGDC-STD-018-2012

Coastal and Marine Ecological Classification Standard, June 2012

Appendix F (Normative): CMECS Biotic Component

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285

Table F1 Biotic Component (Continued).

Biotic Setting Biotic Class Biotic Subclass Biotic Group Biotic Community

Planktonic Biota Floating/Suspended 

Microbes

Films and Strands

Microbial Foam

Microbial Aggregation

Benthic/Attached Biota Reef Biota Deepwater/Coldwater Coral 

Reef Biota

Deepwater/Coldwater Stony Coral Reef Enallopsammia Reef

Goniocorella Reef

Lophelia Reef

Madrepora Reef

Oculina Reef

Solenosmilia Reef

Deepwater/Coldwater Stylasterid Coral 

Reef

Mixed Stylaster Reef

Stylaster Reef

Colonized Deepwater/Coldwater Reef Black Coral Colonized Deepwater/Coldwater Reef 

Gold Coral Colonized Deepwater/Coldwater Reef 

Gorgonian Colonized Deepwater/Coldwater Reef

Mix Colonized Deepwater/Coldwater Reef

Sponge Colonized Deepwater/Coldwater Reef

Shallow/Mesophotic Coral Reef 

Biota

Branching Coral Reef Branching Acropora Reef

Branching Madracis Reef

Branching Pocillopora Reef

Branching Porites Reef

Columnar Coral Reef Columnar Dendrogyra Reef

Columnar Psammocora Reef

Encrusting Coral Reef Encrusting Millepora Reef

Encrusting Portes Reef

Foliose Coral Reef Foliose Agaricia Reef

Foliose Milipora Reef
Federal Geographic Data Committee FGDC-STD-018-2012

Coastal and Marine Ecological Classification Standard, June 2012

Appendix F (Normative): CMECS Biotic Component

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286

Table F1 Biotic Component (Continued).

Biotic Setting Biotic Class Biotic Subclass Biotic Group Biotic Community

Benthic/Attached Biota Reef Biota Shallow/Mesophotic Coral Reef 

Biota

Massive Coral Reef Massive Diploria Reef

Massive Montastraea Reef

Massive Porites Reef

Plate Coral Reef Plate Agaricia Reef

Plate Leptoseris Reef

Plate Montastraea Reef

Table Coral Reef Table Acropora Reef

Turbinate Coral Reef Turbinate Madracis Reef

Mixed Shallow/Mesophotic Coral Reef

Colonized Shallow/Mesophotic Reef Black Coral Colonized Shallow/Mesophotic Reef

Gold Coral Shallow/Mesophotic Reef

Calcalcareous Algae Colonized Shallow/Mesophotic Reef

Coral Garden Reef 

Coralline/Crustose Algae Colonized Shallow/Mesophotic 

Reef

Gorgonian Colonized Shallow/Mesophotic Reef

Soft Coral Colonized Shallow/Mesophotic Reef

Sponge Colonized Shallow/Mesophotic Reef

Glass Sponge Reef Biota Glass Sponge Reef Hexactinosida Reef

Mollusk Reef Biota Gastropod Reef Crepidula Reef

Vermetid Reef

Serpulorbis Reef

Mussel Reef Modiolus Reef

Mytilus Reef

Mollusk Reef Biota Oyster Reef Crassostrea Reef

Ostrea Reef

Worm Reef Biota Sabellariid Reef Phragmatopoma Reef

Sabellaria Reef

Serpulid Reef Serpula vermicularis Reef
Federal Geographic Data Committee FGDC-STD-018-2012

Coastal and Marine Ecological Classification Standard, June 2012

Appendix F (Normative): CMECS Biotic Component

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287

Table F1 Biotic Component (Continued).

Biotic Setting Biotic Class Biotic Subclass Biotic Group Biotic Community

Benthic/Attached Biota Faunal Bed Attached Fauna Mineral Boring Fauna Boring Cliona celata

Boring Penitella

Boring Lithophaga

Wood Boring Fauna Boring Bankia

Boring Limnoria

Boring Teredo

Diverse Colonizers Anemone/Mussel/Bryozoan Colonizers (Large Macrofauna)

Mollusk/Sponge/Tunicate Colonizers (Large Megafauna)

Sponge/Gorgonian Colonizers

Attached Tube-Building Fauna Attached Phoronids

Attached Pogonophorans

Attached Sabellaria

Attached Serpula

Attached Serpulorbis

Vent/Seep Communities Calyptogena Communities

Riftia Communities

Attached Anemones Attached Aiptasia

Attached Metridium

Barnacles Balanus Communities

Chthamalus Communities

Attached Basket Stars Attached Astrophyton

Attached Gorgonocephalus

Attached Brachiopods Attached Crania

Attached Laqueous

Attached Terebratalia

Brittle Stars on Hard or Mixed Substrates Amphipholis Communities

Ophioderma Communities

Ophiothrix Communities
Federal Geographic Data Committee FGDC-STD-018-2012

Coastal and Marine Ecological Classification Standard, June 2012

Appendix F (Normative): CMECS Biotic Component

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288

Table F1 Biotic Component (Continued).

Biotic Setting Biotic Class Biotic Subclass Biotic Group Biotic Community

Benthic/Attached Biota Faunal Bed Attached Fauna Attached Bryozoans Attached Bugula

Attached Celleporaria

Attached Tubulipora

Chitons Attached Acanthopleura

Attached Katharina

Attached Nutallina

Attached Corals Attached Black Corals

Eugorgia Communities

Attached Gold Corals

Attached Gorgonians

Isididae Communities 

Paragorgia Communities

Attached Soft Corals

Attached Crinoids Attached Comanthus

Attached Diplocrinus

Mobile Crustaceans on Hard or Mixed 

Substrates

Caprellid Communities

Crangon Communities

Pagurus Communities

Sessile Gastropods Attached Acmaea

Attached Crepidula

Attached Haliotis

Attached Vermetids

Attached Holothurians Attached Parastichopus

Attached Psolus

Attached Hydroids Attached Sertularia

Attached Tubularia

Mobile Mollusks on Hard or Mixed 

Substrates

Bittium Communities

Littorina Communities

Urosalpinx Communities
Federal Geographic Data Committee FGDC-STD-018-2012

Coastal and Marine Ecological Classification Standard, June 2012

Appendix F (Normative): CMECS Biotic Component

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289

Table F1 Biotic Component (Continued).

Biotic Setting Biotic Class Biotic Subclass Biotic Group Biotic Community

Benthic/Attached Biota Faunal Bed Attached Fauna Attached Mussels Attached Modiolus

Attached Mytilus

Attached Oysters Attached Crassostrea

Attached Ostrea

Attached Sponges Attached Cliona

Attached Halichondria

Attached Hyalonema

Attached Microciona

Attached Scypha

Attached Starfish Attached Asterias

Attached Pisaster

Attached Tunicates Attached Didemnum

Attached Molgula

Attached Sea Urchins Attached Strongylocentrotus droebachiensis

Attached Strongylocentrotus purpurata

Soft Sediment Fauna Larger Deep-Burrowing Fauna Balanoglossus Bed

Boniella Bed

Glycera Bed

Nephtys Bed

Sipunculid Bed

Small Surface-Burrowing Fauna Capitellid Bed

Harpacticoid Bed

Leptocheirus Bed

Lumbrinerid Bed

Nematode Bed

Oligochaete Bed

Turbellarian Bed
Federal Geographic Data Committee FGDC-STD-018-2012

Coastal and Marine Ecological Classification Standard, June 2012

Appendix F (Normative): CMECS Biotic Component

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Table F1 Biotic Component (Continued).

Biotic Setting Biotic Class Biotic Subclass Biotic Group Biotic Community

Benthic/Attached Biota Faunal Bed Soft Sediment Fauna Diverse Soft Sediment Epifauna Aphrodite Bed

Bryozoan/Anemone Bed (Megafauna)

Holothurian/Ophiuroid Bed

Sand Dollar/Sea Pansy/Mobile Mollusk Bed (Large 

Megafauna)

Larger Tube-Building Fauna Robust Ampelisca Bed

Asabellides Bed

Asychis Bed

Chaetopterus Bed

Diopatra Bed

Lagis Bed

Loimia Bed

Phoronid Bed

Phoronopsis Bed

Small Tube-Building Fauna Thin Ampelisca Bed

Chone Bed

Paraprionospio Bed

Polydora Bed

Streblospio Bed

Tunneling Megafauna Callichirus Bed

Lepidophthalmus Bed

Lopholatilus Bed

Neotrypaea Bed

Nephrops Bed

Squilla Bed

Upogebia Bed

Oligozoic Biota Anoxic Oligozoic Bed

Bacterial Bed

Meiofaunal Bed
Federal Geographic Data Committee FGDC-STD-018-2012

Coastal and Marine Ecological Classification Standard, June 2012

Appendix F (Normative): CMECS Biotic Component

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291

Table F1 Biotic Component (Continued).

Biotic Setting Biotic Class Biotic Subclass Biotic Group Biotic Community

Benthic/Attached Biota Faunal Bed Soft Sediment Fauna Burrowing Anemones Cerianthus Bed

Edwardsia Bed

Soft Sediment Basket Stars Asteronyx Bed

Gorgonocephalus arcticus Bed

Brachiopod Bed Glottidia Bed

Lingula Bed

Soft Sediment Brittle Stars Amphiura Bed

Ophiothrix Bed

Ophiura Bed

Soft Sediment Bryozoans Bugula Bed

Celleporaria Bed

Schizoporella Bed

Cephalochordates Amphioxus Bed

Branchiostoma Bed

Clam Bed Arctica Bed

Donax Bed

Macoma Bed

Mercenaria Bed

Mulinia Bed

Mya Bed

Nucula Bed

Rangia Bed

Spisula Bed

Venus Bed

Yoldia Bed

Soft Sediment Crinoids Comanthus Bed

Diplocrinus Bed

Rhizocrinus Bed
Federal Geographic Data Committee FGDC-STD-018-2012

Coastal and Marine Ecological Classification Standard, June 2012

Appendix F (Normative): CMECS Biotic Component

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292

Table F1 Biotic Component (Continued).

Biotic Setting Biotic Class Biotic Subclass Biotic Group Biotic Community

Benthic/Attached Biota Faunal Bed Soft Sediment Fauna Mobile Crustaceans on Soft Sediments Caprellid Bed

Emerita Bed

Haustoriid Bed

Mysid Bed

Pagurus Bed

Echiurid Bed Echiurus Bed

Listriolobus Bed

Urechis Bed

Holothurian Bed Caudina Bed

Kolga Bed

Leptosynapta Bed

Stichopus Bed

Hydroid Bed Sertularia Bed

Tubularia Bed

Mobile Mollusks on Soft Sediments Nassariid Bed

Olivella Bed

Polinices Bed

Scaphopod Bed

Turritellid Bed

Mussel Bed Modiolus Bed

Mytilus Bed

Oyster Bed Crassostrea Bed

Ostrea Bed

Pennatulid Bed Halipteris Bed

Pennatula Bed

Renilla Bed

Stylatula Bed

Sand Dollar Bed Clypeaster Bed

Dendaster elongatus Bed

Mellita Bed
Federal Geographic Data Committee FGDC-STD-018-2012

Coastal and Marine Ecological Classification Standard, June 2012

Appendix F (Normative): CMECS Biotic Component

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293

Table F1 Biotic Component (Continued).

Biotic Setting Biotic Class Biotic Subclass Biotic Group Biotic Community

Benthic/Attached Biota Faunal Bed Soft Sediment Fauna Scallop Bed Argopecten Bed

Placopecten Bed

Sponge Bed Monoraphis Bed

Tetilla mutabilis Bed

Starfish Bed Asterias Bed

Astropecten Bed

Tunicate Bed Ciona Bed

Didemnum Bed

Burrowing Urchins Echinocardium Bed

Lovenia cordiformis Bed

Sea Urchin Bed Lytechinus anamesus Bed

Lytechinus pictus Bed

Inferred Fauna Egg Masses Busycon Egg Cases

Polychaete Mucus Cases

Polynices Egg Collars

Squid Egg Masses

Fecal Mounds Arenicola Castings

Balanoglossid Castings

Holothurian Castings

Pelletized, Fluid Surface Layer Fluidized Capitellid Layer

Fluidized Deposit Feeder Layer

Fluidized Maldanid Layer

Fluidized Yoldia Layer

Tracks and Trails Decapod Tracks

Gastropod Trails

Holothurian Trails

Microbial Communities Structure Forming Microbes Xenophyophores Occultammina Communities

Syringammina Communities

Stromatolites Stromatolite Mound Communities
Federal Geographic Data Committee FGDC-STD-018-2012

Coastal and Marine Ecological Classification Standard, June 2012

Appendix F (Normative): CMECS Biotic Component

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294

Table F1 Biotic Component (Continued).

Biotic Setting Biotic Class Biotic Subclass Biotic Group Biotic Community

Benthic/Attached Biota Microbial Communities Mat/Film Forming Microbes Microphytobenthos Diatom Felt

Microbial Stain

Bacterial Mat/Film Beggiatoa Communities

Bacterial Decay Beggiatoa Communities on Decaying Materials

Vent Microbes Thiobacillus Communities

Thermoacidophiles Communities

Moss and Lichen 

Communities

Freshwater Tidal Lichens Freshwater Submerged and Regularly 

Flooded Tidal Lichen Zone

Freshwater Irregularly Flooded Tidal 

Lichen Zone

Marine Lichens Marine Intertidal Lichen Zone Cocotrema Communities

Lecanora Communities

Intertidal Verrucaria Communities

Marine Supratidal Lichen Zone Anaptychia Communities

Caloplaca Communities

Ramalina Communities

Xanthoria Communities

Supratidal Verrucaria Communities

Freshwater Tidal Moss Submerged Freshwater Tidal Moss Fontinalis antipyretica Nonvascular Vegetation

Emergent Freshwater Tidal Moss

Aquatic Vegetation Bed Benthic Macroalgae Calcareous Algal Bed Corallina Communities

Halimeda Communities

Jania communities

Penicillus Communities

Canopy-Forming Algal Bed Alaria communities

Laminaria saccharina Communities

Macrocystis Communities

Mixed Kelp Communities

Nereocystis Communities
Federal Geographic Data Committee FGDC-STD-018-2012

Coastal and Marine Ecological Classification Standard, June 2012

Appendix F (Normative): CMECS Biotic Component

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295

Table F1 Biotic Component (Continued).

Biotic Setting Biotic Class Biotic Subclass Biotic Group Biotic Community

Benthic/Attached Biota Aquatic Vegetation Bed Benthic Macroalgae Coralline/Crustose Algal Bed Hildenbrandia Communities

Lithothamnion Communities

Lithophyllum Communities

Peyssonnelia Communities

Porolithon Communities

Phymatolithon Communities

Filamentous Algal Bed Aghardiella Communities

Chaetomorpha Communities

Chordaria Communities

Cladophora sericia Communities

Leathery/Leafy Algal Bed Ascophyllum Communities

Caulerpa Communities

Chondrus Communities 

Codium Communities

Fucus distichus Communities

Palmaria Communities

Mesh/Bubble Algal Bed Dichyosphaeria Communities

Valonia Communities

Ventricaria Communities

Sheet Algal Bed Agardhiella Sheet Algae Communities

Grinella americana Communities

Monostroma grevillei Communities

Ulva lactuca Communities

Turf Algal Bed Mixed Algal Turf Communities 

Freshwater and Brackish Tidal Aquatic 

Vegetation

Ceratophyllum demersum - Vallisneria americana - Najas 

spp. Tidal Herbaceous Vegetation

Ruppia maritima - Stuckenia pectinata Herbaceous 

Vegetation
Federal Geographic Data Committee FGDC-STD-018-2012

Coastal and Marine Ecological Classification Standard, June 2012

Appendix F (Normative): CMECS Biotic Component

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296

Table F1 Biotic Component (Continued).

Biotic Setting Biotic Class Biotic Subclass Biotic Group Biotic Community

Benthic/Attached Biota Aquatic Vegetation Bed Aquatic Vascular Vegetation Seagrass Bed Ruppia maritima Herbaceous Vegetation

Syringodium filiformis - (Thalassia testudinum) Herbaceous 

Vegetation

Halodule wrightii Herbaceous Vegetation

Halophila decipiens Herbaceous Vegetation [Provisional]

Halophila engelmannii Herbaceous Vegetation

Halophila hawaiiana Herbaceous Vegetation [Provisional]

Halophila johnsonii Herbaceous Vegetation [Provisional]

Halophila minor Herbaceous Vegetation [Provisional]

Halophila ovalis Herbaceous Vegetation [Provisional]

Phyllospadix scouleri Herbaceous Vegetation [Provisional]

Phyllospadix serrultus Herbaceous Vegetation[Provisional]

Phyllospadix torreyi Herbaceous Vegetation [Provisional]

Thalassia testudinum - Syringodium filiformis Herbaceous 

Vegetation

Thalassia testudinum Herbaceous Vegetation

Vallisneria americana Estuarine Bayou Herbaceous 

Vegetation

Zostera marina Herbaceous Vegetation

Emergent Wetland Emergent Tidal Marsh Brackish Marsh Amaranthus cannabinus Tidal Herbaceous Vegetation

Calamagrostis nutkaensis - Argentina egedii - Juncus 

balticus Herbaceous Vegetation

Carex hyalinolepis Tidal Herbaceous Vegetation

Paspalum vaginatum - Spartina patens Oligohaline 

Herbaceous Vegetation

Phragmites australis Tidal Herbaceous Vegetation

Sagittaria subulata - Limosella australis Tidal Herbaceous 

Vegetation

Schoenoplectus americanus - (Spartina patens) - Typha 

spp. Herbaceous Vegetation

Schoenoplectus pungens Tidal Herbaceous Vegetation
Federal Geographic Data Committee FGDC-STD-018-2012

Coastal and Marine Ecological Classification Standard, June 2012

Appendix F (Normative): CMECS Biotic Component

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Table F1 Biotic Component (Continued).

Biotic Setting Biotic Class Biotic Subclass Biotic Group Biotic Community

Benthic/Attached Biota Emergent Wetland Emergent Tidal Marsh Brackish Marsh Schoenoplectus robustus - Spartina alterniflora Herbaceous 

Vegetation

Spartina alterniflora - Lilaeopsis chinensis Herbaceous 

Vegetation

Spartina alterniflora - Polygonum punctatum - Amaranthus 

cannabinus Herbaceous Vegetation

Spartina cynosuroides Herbaceous Vegetation

Spartina patens - Typha spp. Chenier Plain Oligohaline 

Herbaceous Vegetation

Spartina patens - Vigna luteola Mississippi River Deltaic 

Plain Herbaceous Vegetation

Typha angustifolia - Hibiscus moscheutos Herbaceous 

Vegetation

Typha domingensis Tidal Herbaceous Vegetation

Freshwater Tidal Marsh Acorus calamus Tidal Herbaceous Vegetation

Ambrosia trifida Herbaceous Vegetation

Bidens cernua Herbaceous Vegetation [Provisional]

Carex obnupta - Argentina egedii ssp. egedii Herbaceous 

Vegetation

Carex obnupta - Juncus patens Herbaceous Vegetation

Carex obnupta Herbaceous Vegetation

Carex stricta - Peltandra virginica - Sagittaria (lancifolia ssp. 

media, latifolia) Tidal Herbaceous Vegetation

Cladium mariscus ssp. jamaicense Tidal Herbaceous 

Vegetation

Deschampsia caespitosa - Horkelia marinensis Herbaceous 

Vegetation

Eleocharis fallax - Eleocharis rostellata - Schoenoplectus 

americanus - Sagittaria lancifolia Herbaceous Vegetation

Eleocharis rostellata - Rhynchospora colorata - 

Rhynchospora microcarpa Herbaceous Vegetation

Eleocharis rostellata - Sagittaria lancifolia Oligohaline 

Herbaceous Vegetation
Federal Geographic Data Committee FGDC-STD-018-2012

Coastal and Marine Ecological Classification Standard, June 2012

Appendix F (Normative): CMECS Biotic Component

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298

Table F1 Biotic Component (Continued).

Biotic Setting Biotic Class Biotic Subclass Biotic Group Biotic Community

Benthic/Attached Biota Emergent Wetland Emergent Tidal Marsh Freshwater Tidal Marsh Eriocaulon parkeri - Polygonum punctatum Herbaceous 

Vegetation

Hibiscus moscheutos - Polygonum punctatum - Peltandra 

virginica Tidal Herbaceous Vegetation

Impatiens capensis - Peltandra virginica - Polygonum 

arifolium - Schoenoplectus fluviatilis - Typha angustifolia 

Tidal Herbaceous Vegetation

Isoetes riparia Tidal Herbaceous Vegetation

Juncus balticus - Carex obnupta Herbaceous Vegetation 

[Provisional]

Juncus effusus var. brunneus Pacific Coast Herbaceous 

Vegetation

Juncus falcatus - Trifolium wormskioldii Herbaceous 

Vegetation

Juncus roemerianus - Pontederia cordata Herbaceous 

Vegetation

Justicia americana - Peltandra virginica Herbaceous 

Vegetation [Provisional]

Nelumbo lutea Tidal Herbaceous Vegetation

Nuphar advena Tidal Herbaceous Vegetation

Nuphar sagittifolia Tidal Herbaceous Vegetation

Peltandra virginica - Pontederia cordata Tidal Herbaceous 

Vegetation

Peltandra virginica - Schoenoplectus (pungens, 

tabernaemontani) Tidal Herbaceous Vegetation

Phragmites australis - (Sagittaria platyphylla, Vigna luteola) 

Tidal Herbaceous Vegetation

Sagittaria lancifolia - Glottidium vesicarium - Solidago 

sempervirens - Lythrum lineare Herbaceous Vegetation

Sagittaria lancifolia Mississippi River Deltaic Plain 

Herbaceous Vegetation

Sagittaria latifolia - Sagittaria platyphylla - (Colocasia 

esculenta) Deltaic Herbaceous Vegetation
Federal Geographic Data Committee FGDC-STD-018-2012

Coastal and Marine Ecological Classification Standard, June 2012

Appendix F (Normative): CMECS Biotic Component

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299

Table F1 Biotic Component (Continued).

Biotic Setting Biotic Class Biotic Subclass Biotic Group Biotic Community

Benthic/Attached Biota Emergent Wetland Emergent Tidal Marsh Freshwater Tidal Marsh Schoenoplectus californicus Tidal Herbaceous Vegetation

Schoenoplectus pungens - (Osmunda regalis var. 

spectabilis ) Herbaceous Vegetation

Spartina cynosuroides - Panicum virgatum - Phyla 

lanceolata Herbaceous Vegetation

Zizania aquatica Gulf Coast Herbaceous Vegetation

Zizania aquatica Tidal Herbaceous Vegetation

Zizaniopsis miliacea - Panicum hemitomon Herbaceous 

Vegetation

Zizaniopsis miliacea Tidal Herbaceous Vegetation

High Salt Marsh Argentina egedii - Juncus balticus Herbaceous Vegetation

Argentina egedii - Symphyotrichum subspicatum 

Herbaceous Vegetation

Carex lyngbyei - Argentina egedii Herbaceous Vegetation

Deschampsia caespitosa - Argentina egedii Herbaceous 

Vegetation

Deschampsia caespitosa - Sidalcea hendersonii 

Herbaceous Vegetation

Eleocharis rostellata - Spartina patens Herbaceous 

Vegetation

Festuca rubra - (Argentina egedii) Herbaceous Vegetation

Juncus roemerianus Herbaceous Vegetation

Panicum virgatum - (Cladium mariscus ssp. jamaicense, 

Juncus roemerianus) Herbaceous Vegetation

Panicum virgatum - Spartina patens Herbaceous Vegetation

Schoenoplectus americanus - Spartina patens Herbaceous 

Vegetation Schoenoplectus pungens - Eleocharis parvula Herbaceous 

Vegetation Spartina bakeri - Kosteletzkya virginica Herbaceous 

Vegetation

Spartina bakeri Herbaceous Vegetation
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Table F1 Biotic Component (Continued).

Biotic Setting Biotic Class Biotic Subclass Biotic Group Biotic Community

Benthic/Attached Biota Emergent Wetland Emergent Tidal Marsh High Salt Marsh Spartina patens - Agrostis stolonifera Herbaceous 

Vegetation Spartina patens - Distichlis spicata - (Juncus roemerianus) 

Herbaceous Vegetation

Spartina patens - Festuca rubra - (Spartina pectinata) 

Herbaceous Vegetation

Low and Intermediate Salt Marsh Acrostichum aureum - (Acrostichum danaeifolium) Tidal 

Herbaceous Vegetation

Carex lyngbyei - (Distichlis spicata, Triglochin maritima) 

Herbaceous Vegetation

Carex lyngbyei Herbaceous Vegetation

Deschampsia caespitosa - (Carex lyngbyei, Distichlis 

spicata) Herbaceous Vegetation

Distichlis spicata - (Salicornia virginica) Herbaceous 

Vegetation

Distichlis spicata - Ambrosia chamissonis Herbaceous 

Vegetation

Salicornia (bigelovii, virginica) Tidal Herbaceous Vegetation 

[Provisional]

Salicornia virginica - Brassica nigra Herbaceous Vegetation

Salicornia virginica - Distichlis spicata - Jaumea carnosa 

Tidal Herbaceous Vegetation

Salicornia virginica - Distichlis spicata - Triglochin maritima - 

(Jaumea carnosa) Herbaceous Vegetation

Salicornia virginica - Frankenia salina - Suaeda californica 

Herbaceous Vegetation

Salicornia virginica / Algae Herbaceous Vegetation

Salicornia virginica Herbaceous Vegetation

Sesuvium portulacastrum Tidal Herbaceous Vegetation 

[Placeholder]

Spartina alterniflora - Distichlis spicata - Spartina patens 

Mesohaline Tidal Herbaceous Vegetation

Spartina alterniflora - Juncus roemerianus - Distichlis 

spicata Louisianian Zone Salt Tidal Herbaceous Vegetation
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Table F1 Biotic Component (Continued).

Biotic Setting Biotic Class Biotic Subclass Biotic Group Biotic Community

Benthic/Attached Biota Emergent Wetland Emergent Tidal Marsh Low and Intermediate Salt Marsh Spartina alterniflora - Distichlis spicata Tidal Herbaceous 

Vegetation

Spartina alterniflora / (Ascophyllum nodosum) 

Acadian/Virginian Zone Herbaceous Vegetation

Spartina alterniflora Carolinian Zone Herbaceous Vegetation

Spartina patens - Distichlis spicata - (Juncus gerardii) 

Herbaceous Vegetation

Spartina patens - Schoenoplectus (americanus, pungens) - 

(Distichlis spicata) Herbaceous Vegetation

Spartina foliosa Herbaceous Vegetation

Triglochin maritima - (Salicornia virginica) Herbaceous 

Vegetation

Vegetated Tidal Flats Vegetated Freshwater Tidal Mudflat

Vegetated Salt Flat and Panne Batis maritima - Sarcocornia pacifica Dwarf-shrubland

Batis maritima Dwarf-shrubland

Distichlis spicata - (Sporobolus virginicus) Herbaceous 

Vegetation

Monanthochloe littoralis Herbaceous Vegetation

Salicornia (virginica, bigelovii, maritima) - Spartina 

alterniflora Herbaceous Vegetation

Salicornia bigelovii - Triglochin maritima Herbaceous 

Vegetation

Sarcocornia pacifica - (Batis maritima, Distichlis spicata) 

Dwarf-shrubland

Spartina spartinae - Monanthochloe littoralis - Suaeda 

linearis Herbaceous Vegetation

Spartina spartinae - Sporobolus virginicus Tidal Herbaceous 

Vegetation

Sporobolus virginicus - Distichlis spicata Herbaceous 

Vegetation

Sporobolus virginicus - Paspalum vaginatum Herbaceous 

Vegetation
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Table F1 Biotic Component (Continued).

Biotic Setting Biotic Class Biotic Subclass Biotic Group Biotic Community

Benthic/Attached Biota Scrub-Shrub Wetland Tidal Scrub-Shrub Wetland Brackish Tidal Scrub-Shrub Lonicera involucrata / Argentina egedii Tidal Shrubland 

[Provisional]

Freshwater Tidal Scrub-Shrub Alnus (incana ssp. rugosa, serrulata ) - Cornus amomum 

Shrubland

Alnus maritima / Acorus calamus Shrubland

Alnus serrulata - Salix nigra / Pilea (fontana, pumila) Tidal 

Shrubland

Alnus serrulata / (Zizania aquatica, Zizaniopsis miliacea) 

Shrubland

Amorpha fruticosa Tidal Shrubland

Morella cerifera - Rosa palustris / Thelypteris palustris var. 

pubescens Shrubland

Morella cerifera - Toxicodendron radicans / Spartina bakeri 

Shrubland

Saltwater Tidal Scrub-Shrub Borrichia arborescens Shrubland

Borrichia frutescens / (Spartina patens, Juncus 

roemerianus) Shrubland

Borrichia frutescens / Spartina spartinae Shrubland

Baccharis halimifolia - Iva frutescens - Morella cerifera - (Ilex 

vomitoria) Shrubland

Baccharis halimifolia - Iva frutescens / Panicum virgatum 

Shrubland

Iva frutescens ssp. frutescens - Baccharis halimifolia / 

Spartina spartinae Shrubland

Iva frutescens / Spartina patens Shrubland

Avicennia germinans / Spartina alterniflora Shrubland

Morella cerifera - Baccharis halimifolia / Eleocharis fallax 

Shrubland

Iva frutescens / Spartina cynosuroides Tidal Shrubland
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Table F1 Biotic Component (Continued).

Biotic Setting Biotic Class Biotic Subclass Biotic Group Biotic Community

Benthic/Attached Biota Scrub-Shrub Wetland Tidal Scrub-Shrub Wetland Tidal Mangrove Shrubland Rhizophora mangle Shrubland

Rhizophora mangle - Avicennia germinans - Laguncularia 

racemosa / Batis maritima Shrubland

Rhizophora mangle - Avicennia germinans - Laguncularia 

racemosa Shrubland

Rhizophora mangle - Avicennia germinans Shrubland

Avicennia germinans / Batis maritima Shrubland

Avicennia germinans / Sarcocornia pacifica Shrubland

Forested Wetland Tidal Forest/Woodland Brackish Tidal Forest/Woodland Picea sitchensis / Lonicera involucrata - Malus fusca Tidal 

Woodland [Provisional]

Freshwater Tidal Forest/Woodland Juniperus virginiana var. silicicola / Morella cerifera / 

Kosteletzkya virginica - Bacopa monnieri Woodland

Nyssa aquatica Tidal Forest

Nyssa biflora - Nyssa aquatica - Taxodium distichum / 

Saururus cernuus Forest

Pinus taeda - Nyssa biflora - Taxodium distichum / Morella 

cerifera / Osmunda regalis var. spectabilis Forest

Nyssa biflora - (Taxodium distichum, Nyssa aquatica) / 

Morella cerifera - Rosa palustris Tidal Forest

Taxodium distichum / Carex hyalinolepis Woodland

Taxodium distichum / Typha angustifolia Woodland

Taxodium distichum / Zizania aquatica - Carex canescens 

ssp. disjuncta Woodland

Taxodium distichum Tidal Woodland [Provisional]

Taxodium distichum / Pontederia cordata - Peltandra 

virginica Tidal Woodland

Taxodium ascendens - Cliftonia monophylla - Pinus elliottii 

var. elliottii - Chamaecyparis thyoides / Hypericum nitidum - 

Cladium mariscus ssp.

Taxodium distichum - Nyssa aquatica - Persea palustris 

Forest
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Table F1 Biotic Component (Continued).

Biotic Setting Biotic Class Biotic Subclass Biotic Group Biotic Community

Benthic/Attached Biota Forested Wetland Tidal Forest/Woodland Freshwater Tidal Forest/Woodland Taxodium distichum - Nyssa biflora - Magnolia virginiana - 

Fraxinus profunda Forest

Nyssa biflora - Magnolia virginiana / Cyrilla racemiflora 

Forest

Nyssa biflora - Magnolia virginiana - Sabal palmetto - 

Juniperus virginiana var. silicicola Forest

Acer rubrum - Fraxinus pennsylvanica / Polygonum spp. 

Forest

Acer rubrum / Sambucus canadensis / Ampelopsis arborea - 

Sicyos angulatus Forest

Fraxinus profunda - Nyssa biflora - (Fraxinus pennsylvanica) 

/ Ilex verticillata / Polygonum arifolium Forest

Fraxinus pennsylvanica - (Ulmus americana) - Pinus taeda / 

Morella cerifera - Juniperus virginiana var. silicicola Tidal 

Forest

Saltwater Tidal Forest/Woodland Tamarisk Tidal Forest [Provisional]

Melaleuca Tidal Forest [Provisional]

Tidal Mangrove Forest Avicennia germinans Forest

Conocarpus erectus Forest

Rhizophora mangle Basin Forest

Rhizophora mangle Fringe Forest

Rhizophora mangl e Medium Island Forest

Rhizophora mangle Overwash Island Forest

Rhizophora mangle Tall Fringing Forest

Rhizophora mangle - (Avicennia germinans, Laguncularia 

racemosa) Riverine Forest

Rhizophora mangle - Dalbergia ecastaphyllum - Pavonia 

paludicola Forest
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Appendix G (Informative): CMECS Crosswalk with the 

Classification of Wetlands and Deepwater Habitats in the 

United States, FGDC-STD-004
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Developers of Coastal and Marine Ecological Classification Standard (CMECS) have worked 

closely with staff of the National Wetland Inventory to establish as much consistency between 

CMECS and FGDC-STD-004 as possible—while still attaining the goals of CMECS. The 

desired outcome of this coordination was to enable a logical seam between FGDC-STD-004 

and CMECS that would ensure a continuous database from the continental divide to beyond 

the continental shelf. The earliest attempts to define this seam have not stood up to critical 

thinking. Currently, the simplest breakpoint seems to be between wetlands and subtidal or 

permanently flooded-tidal habitats. Therefore, staff supporting FGDC-STD-004 proposed the 

following to simplify the seam and establish a solution that can stand the test of time: 

“The National Wetlands Classification Standard (NWCS) will be used to map all non-tidal 

deepwater habitats except for the Great Lakes and all wetlands except for permanently 

flooded-tidal freshwater wetlands. Once CMECS is endorsed by the FGDC, CMECS will be 

used to map deepwater habitats in the Great Lakes and in the Marine and Estuarine Systems, 

as well as all permanently flooded-tidal freshwater habitats (deepwater and wetland). The 

NWCS will use 0.5 parts per thousand (ppt) ocean-derived salinity as the upstream boundary 

for the Estuarine System and CMECS will use head of tide.”

At the highest level, FGDC-STD-004 classifies wetlands and deepwater habitats into systems 

and subsystems; the subsystems are defined by tidal regime. In CMECS, the subsystems are 

primarily defined by depth. CMECS was developed this way to enable users to better classify 

marine ecosystem as depth plays a significant role in the ecological functioning of these systems.

The tables below provide a crosswalk between CMECS units and FGDC-STD-004.

Table G1. Crosswalk between FGDC-STD-004 and CMECS Systems, Subsystems, and Tidal 

Zone.

FGDC-STD-004

System/Subsystem

CMECS

System/Subsystem/Tidal Zone

Marine

Subtidal

Subtidal

Subtidal

Intertidal

No equivalent

Marine

Oceanic (Zm is > shelf break)

Subtidal

Offshore (Zm is > 30 meters up to shelf break)

Subtidal

Nearshore (Zm is 0–30 meters)

Subtidal

Intertidal

Supratidal
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FGDC-STD-004

System/Subsystem

CMECS

System/Subsystem/Tidal Zone

Estuarine

Subtidal

Intertidal

No equivalent

Estuarine

Estuarine Coastal (Zm is 0–4 meters)

Subtidal

Intertidal

Supratidal

Subtidal

Subtidal

Intertidal

No equivalent

Subtidal

Estuarine Open Water (Zm is > 4 meters)

Subtidal

Tidal Riverine Coastal (Zm is 0–4 meters)

Subtidal

Intertidal

Supratidal

Tidal Riverine Open Water (Zm is > 4 meters)

Subtidal

Lacustrine

Limnetic

Littoral

Lacustrine

Limnetic

Littoral
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Table G2. Crosswalk between FGDC-STD-004 and CMECS Substrate Component Classes and 

Subclasses. Because CMECS Substrate Component goes into greater detail on substrate origin 

and composition, the CMECS units for Substrate Origin and Group are also shown.

FGDC-STD-004

Class/Subclass

CMECS

Substrate Component

Origin/Class/Subclass/Group

Geologic Substrate

Rocky Shore/Rock bottom Class Rock Substrate Class

Bedrock Subclass Bedrock Subclass

Rubble Subclass No equivalent

No equivalent Megaclast Subclass

Unconsolidated Shore/Bottom Classes Unconsolidated Mineral Substrate Class

Cobble/Gravel Subclass Coarse Unconsolidated Substrate Subclass

Subclass level Gravel Group

Subclass level Gravel Mixes Group

Subclass level Gravelly Group

Class level Fine Unconsolidated Substrate Subclass

No equivalent Slightly Gravelly Group

Sand Subclass Sand Group

No equivalent Muddy Sand Group

No equivalent Sandy Mud Group

Mud Subclass Mud Group

Biogenic Substrate

No equivalent Algal Substrate Class

No equivalent Algal Sand Subclass

No equivalent Halimeda Sand Group

No equivalent Rhodolith Substrate Subclass

No equivalent Rhodolith Rubble Group

No equivalent Rhodolith Hash Group

No equivalent Rhodolith Sand Group

Reef Class Coral Substrate Class

Coral Subclass Coral Reef Substrate Subclass

Coral Subclass Coral Rubble Subclass

Coral Subclass Coral Hash Subclass

Coral Subclass Coral Sand Subclass

Organic Subclass

Organic Subclass

Organic Subclass

Organic Substrate Class

Organic Debris Subclass

Peat Debris Group 

Woody Debris Group
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FGDC-STD-004

Class/Subclass

CMECS

Substrate Component

Origin/Class/Subclass/Group

Organic Subclass Organic Detritus Subclass

Organic Subclass Organic Mud Subclass

No equivalent Carbonate Ooze Subclass 

No equivalent Coccolithophore Ooze Group

No equivalent Foraminiferan Ooze Group

No equivalent Pteropod Ooze Group

No equivalent Silicious Ooze Subclass

No equivalent Diatomaceous Ooze Group

No equivalent Radiolarian Ooze Group

Reef Class Shell Substrate Class

No equivalent Shell Reef Substrate Subclass

No equivalent Clam Reef Substrate Group

No equivalent Crepidula Reef Substrate Group

No equivalent Mussel Reef Substrate Group

Mollusk Subclass Oyster Reef Substrate Group

Reef Class Shell Rubble Subclass

No equivalent Clam Rubble Group

No equivalent Crepidula Rubble Group

No equivalent Mussel Rubble Group

Mollusk Subclass Oyster Rubble Group

No equivalent Shell Hash Subclass

No equivalent Clam Hash Group

No equivalent Crepidula Hash Group

No equivalent Mussel Hash Group

Mollusk Subclass Oyster Hash Group

No equivalent Shell Sand Subclass

No equivalent Coquina Sand Group

Worm Subclass Worm Substrate Class

No equivalent Sabellariid Substrate Subclass

No equivalent Sabellariid Reef Substrate Group

No equivalent Sabellariid Rubble Group

No equivalent Sabellariid Hash Group

No equivalent Serpulid Substrate Subclass

No equivalent Serpulid Reef Substrate Group

No equivalent Serpulid Rubble Group

No equivalent Serpulid Hash Group
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FGDC-STD-004

Class/Subclass

CMECS

Substrate Component

Origin/Class/Subclass/Group

Anthropogenic Substrate

No equivalent Anthropogenic Rock Class

No equivalent Anthropogenic Rock Reef Substrate Subclass

Anthropogenic Rock Rubble Subclass

No equivalent Anthropogenic Rock Hash Subclass

No equivalent Anthropogenic Rock Sand Subclass

No equivalent Anthropogenic Rock Mud Subclass

No equivalent Anthropogenic Wood Class

Anthropogenic Wood Reef Substrate Subclass

Anthropogenic Wood Rubble Subclass

Anthropogenic Wood Hash Subclass

No equivalent Construction Materials Class

No equivalent Construction Reef Substrate Subclass

Construction Rubble Subclass

Construction Hash Subclass

Metal Class

Metal Reef Substrate Subclass

Metal Rubble Subclass

Metal Hash Subclass

Trash

Trash Rubble

Trash Bits
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Table G3. Crosswalk between FGDC-STD-004 and CMECS Biotic Component Classes and 

Subclasses. Because CMECS Biotic Component establishing biotic classes and subclasses based 

largely on the location of the biota, the Biotic Setting is also shown. Biotic Groups are not 

provided in the table because there are an extensive number of groups and no equivalent units 

occur in FGDC-STD-004.

FGDC-STD-004

Class/Subclass

CMECS

Biotic Component

Setting/Class/Subclass

Planktonic Biota

No equivalent Zooplankton Class

No equivalent Crustacean Holoplankton Subclass

No equivalent Crustacean Meroplankton Subclass

No equivalent Coral Meroplankton

No equivalent Echinoderm Meroplankton

No equivalent Fish Meroplankton

No equivalent Gelatinous Zooplankton

No equivalent Mixed Zooplankton

No equivalent Molluscan Holoplankton

No equivalent Molluscan Meroplankton

No equivalent Protozoan Holoplankton

No equivalent Worm Holoplankton

No equivalent Worm Meroplankton

Aquatic Bed Class Floating/Suspended Plants and Macroalgae Class

No equivalent Floating/Suspended Macroalgae Subclass

Floating Vascular Subclass Floating/Suspended Vascular Vegetation Subclass

No equivalent Phytoplankton Class

No equivalent Chlorophyte Phytoplankton Subclass

No equivalent Chrysophyte Phytoplankton Subclass

No equivalent Coccolithophore Phytoplankton Subclass

No equivalent Cryptophyte Phytoplankton Subclass

No equivalent Cyanophyte Phytoplankton Subclass

No equivalent Diatom Phytoplankton Subclass

No equivalent Dinoflagellate Phytoplankton Subclass

No equivalent Floating/Suspended Microbes Class

No equivalent Microbial Films and Strands Subclass

No equivalent Microbial Foam Subclass

No equivalent Microbial Discoloration Subclass
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FGDC-STD-004

Class/Subclass

CMECS

Biotic Component

Setting/Class/Subclass

Benthic/Attached Biota

Reef Class Reef Biota Class

Coral Subclass Deepwater/Coldwater Coral Reef Biota Subclass

Coral Subclass Shallow/Mesophotic Coral Reef Biota Subclass

Mollusk Subclass Mollusk Reef Biota Subclass

Worm Subclass Worm Reef Biota Subclass

No equivalent Faunal Bed Class

No equivalent Attached Fauna Subclass

No equivalent Soft Sediment Fauna Subclass

No equivalent Inferred Fauna Subclass

No equivalent Microbial Communities Class 

No equivalent Structure-Forming Microbes Subclass

No equivalent Mat/Film-Forming Microbes Subclass

Moss-Lichen Wetland Class Mosses and Lichen Communities Class

Moss Subclass Freshwater Tidal Moss Subclass

Lichen Subclass Freshwater Tidal Lichens Subclass

Lichen Subclass Marine Lichens Subclass

Aquatic Bed Class Aquatic Vegetation Class

Algal Subclass Benthic Macroalgae Subclass

Aquatic Moss Subclass Tidal Moss Subclass under Mosses and Lichens Class

Rooted Vascular Subclass Aquatic Vascular Vegetation Subclass

Floating Vascular Subclass Floating/Suspended Vascular Vegetation Subclass under 

Floating/Suspended Plants and Macroalgae Class

Emergent Wetland Class Emergent Wetland Class

No equivalent Emergent Tidal Marsh Subclass

No equivalent Sparsely Vegetated Tidal Flats Subclass

Persistent Subclass Modifier

Non-Persistent Subclass Modifier

Scrub-Shrub Wetland Class Scrub-Shrub Wetland Class

No equivalent Tidal Scrub-Shrub Wetland Subclass

Needle-Leaved Evergreen Subclass No equivalent

Broad-Leaved Evergreen No equivalent

Needle-Leaved Deciduous No equivalent

Broad-Leaved Deciduous No equivalent

Dead No equivalent
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FGDC-STD-004

Class/Subclass

CMECS

Biotic Component

Setting/Class/Subclass

Forested Wetland Class

No equivalent

Needle-Leaved Evergreen Subclass 

Broad-Leaved Evergreen Subclass 

Needle-Leaved Deciduous Subclass 

Broad-Leaved Deciduous Subclass 

Dead Subclass

Tidal Forest/Woodland Subclass

No equivalent 

No equivalent 

No equivalent 

No equivalent 

No equivalent
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Appendix H (Informative): CMECS Best Practices in 

Crosswalking
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Introduction

One of the critical objectives of the Coastal and Marine Ecological Classification 

Standard (CMECS) is interoperability with other classifications and datasets. Once 

CMECS is endorsed as a Federal Geographic Data Committee (FGDC) standard, users 

receiving federal funds for classification of coastal and marine ecological units will be 

required to, at a minimum, crosswalk their source classification units to the CMECS 

standard. This guidance outlines the concepts and issues associated with crosswalking 

data from individual source classifications to the CMECS classification, and it also 

provides guidance on best practices for reporting source units into the CMECS 

framework.

Concepts

Crosswalking can be done to compare the conceptual units from one classification to 

units in another classification (unit-to-unit crosswalking) or relate observational data 

(samples, plots, or mapped polygons) that are collected using one classification to another 

classification (observation-to-unit crosswalking).

Unit-to-Unit Crosswalking

Unit-to-unit crosswalking is needed for identifying the relationship between individual 

units from a source classification and CMECS units. Unit-to-unit crosswalking requires a 

comparison of the concepts and circumscriptions of the units in both classifications in 

order to make the relationships between them explicit. Examples of situations where unitto-unit crosswalking may be required include identifying the relationships between the 

units in a specific classification (the FGDC Wetland Classification [FGDC 1996] to 

CMECS) or e.g., assigning a CMECS unit name to a unit described in the literature that 

uses a different classification scheme.

Observation-to-Unit Crosswalking

Making the best use of existing data is a critical need for most users. Users have two 

potential pathways to take advantage of existing observation data for reporting to 

CMECS. These include re-analysis of the source data and re-interpretation of observation 

data.

Re-analysis of Source Observation Data

Re-analysis of source data requires de novo classification of the data using the CMECS 

framework; it does not require any crosswalking. Whenever feasible, re-analysis of the 

source data using the CMECS framework will result in the most accurate reporting of 

CMECS units, assuming the data needed to assign CMECS units are available in the 

source datasets.
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Re-interpretation of Observation Data or Derived-Data Products

Re-interpretation of observation data or derived-data products (like maps) requires the 

user to make explicit the relationship between the observations (e.g., samples, plots, and 

polygons) and CMECS units. Perhaps the most common examples of re-interpretation of 

data products are (a) crosswalking individual map polygons to CMECS or (b) labeling 

grab samples with CMECS units. Because observation data have specific measurable 

parameters associated with them (rather than a range for a conceptual unit description), 

they can often be more precisely attributed to a CMECS unit—provided the necessary 

data have been collected.

Crosswalking Methodology

Making the relationships between the units in the source classification and CMECS 

explicit is essential to effectively crosswalking the units. Comparison of units from one 

classification to another requires a thorough understanding of all the units, their 

thresholds, and any implementation conventions.

The following guidance suggests the minimum required metadata for the crosswalking 

process. This approach is an adaptation of the Taxonomic Data Working Group (Franz, 

Peet, and Weakley 2008) crosswalking model. The approach applies both to unit-to-unit 

crosswalking and to observation-to-unit crosswalking.

General Approach

 Wherever possible, review the original source data for the project. If these are 

available, they will allow more informed crosswalking from the source unit to the 

CMECS unit.

 Create a unit-to-unit crosswalk as a first step, employing the crosswalking 

approach described below to make the relationships explicit. Spreadsheets or 

tables are useful tools to help visualize the relationships. If the units are numerous 

and the relationships complex, creating a database that tracks the relationships 

between units may be a worthwhile effort.

 Automate where possible to help make the connections between observations and 

units. Develop algorithms for observation-to-unit crosswalks to facilitate 

crosswalking. However, it should be noted that some relationships can only be 

rectified with human interpretation of the source data.

 Incorporate other ancillary data if that meets your objectives. If source data for a 

study were not collected with CMECS thresholds in mind, identify other datasets 

that can be combined with the source data to help make the relationship to 

CMECS units clearer.
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 When crosswalking observations to CMECS units, maintain any specific data that 

are at a finer scale than CMECS units and consider applying CMECS modifiers 

so the necessary detail is not lost.

 Only crosswalk to CMECS based on the source data you have. If the data are not 

available, it may be impossible to crosswalk some data.

Crosswalking Standard

Complete the following fields of information for each unit in the source classification. 

See Table H1 for an example of the standard applied to a unit-to-unit crosswalk between 

FGDC-STD-004 (FGDC 1996) classification substrate types and CMECS substrate units.

 Unit Name in the Source Study – Names of the units that are noted in the study

using the source terminology.

 Concept Reference for Source Unit – Name and reference for the source 

classification.

 CMECS Name – The most closely related CMECS name(s) for the unit(s) 

identified in the study, from any level or any component that is related to the units 

in the first field. Users can list one-to-many CMECS names that relate to the data,

preferably at the most appropriate level of the hierarchy.

 Relationship of the Source Units to CMECS Unit(s) – Description of the 

relationship between the unit(s) in the study and the CMECS unit name(s) listed 

with the following qualifiers:

o Equal (=): There is a one-to-one relationship between the source unit and 

the CMECS unit. The names of the units may or may not be the same. 

Units with “equal” relationships—but different names—are considered 

synonyms.

Example: The terms “gravel” and “pebbles” are used in different 

classifications to mean the same thing.

o Nearly Equal (≈): The source unit is nearly equivalent to the CMECS unit. 

The thresholds or concepts vary by a small—but insignificant—way for 

most practical applications.

Example: The definition for “Mud” in the FGDC (1996) classification has 

a very small difference in the threshold for particle size than the 

“Undifferentiated Silt and Clay (mud)” unit in CMECS. The difference is 

less than 0.012 millimeters.

o Greater Than (>): The source unit is more broadly defined than the 

CMECS unit. The threshold range for the source unit definition is wider 
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than the threshold range of the CMECS unit definition. The concept of the 

source unit fully contains the concept of the CMECS unit, but the source 

unit also includes additional entities.

Example: There is a one-to-many relationship between the Florida 

SCHEME classification (Madley, Sargent, and Sargent 2002) for the 

“Reef/Hardbottom” class and the CMECS Coral Reef, Mollusk Reef, 

Worm Reef, and Bedrock units. The Reef/Hardbottom Class is greater 

than each of the related CMECS units.

o Less Than (<): The source unit is more finely classified than the CMECS 

unit. The threshold range for the source unit definition is narrower than the 

threshold range of the CMECS unit definition. The source unit concept is 

fully included in the CMECS unit, but the latter concept contains 

additional entities.

Example: The FGDC (1996) “Bedrock” unit is finer than the CMECS 

“Bedrock” unit. The FGDC threshold for defining bedrock requires that 

the area be covered by at least 75% bedrock, whereas the CMECS

definition requires the area to be covered by at least 50% bedrock. So 

although the names are the same, the concept definitions based on their 

threshold values are different.

o Overlapping (><): The source unit is not clearly broader or finer than the

CMECS unit. The two concepts contain at least one common entity, and 

each concept also contains at least one entity that the other does not 

contain. Neither concept is fully contained in the other.

o No Equivalent (<>): The source unit does not have a clearly related unit in 

the CMECS classification.

Example: The SCHEME (Madley, Sargent, and Sargent 2002) 

classification recognizes a type called “Platform Reef” that has no related 

concept in CMECS, and CMECS recognizes a “Microbial Mat” unit that 

has no related concept in SCHEME. This case most often arises when a 

source classification has a different objective than that of CMECS—or if 

the source classification has been developed to describe local, more 

detailed ecological units.

o Unknown (?): The relationship between the source unit and CMECS units 

is unknown. Although some correlation is likely, a determination cannot 

be made from the data provided in the source study.
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CMECS Relationship Confidence

For each value entered in the “Relationship to CMECS Unit” column, use the following 

values to indicate confidence in assigning the relationship between the CMECS unit 

names and the habitat units in the study.

 Certain: Either CMECS was used as the habitat classification for the study, or

there is evidence (textual or data) in the study for the relationship between habitat 

names in the study and CMECS units. If exact CMECS names are not used, wellestablished synonyms or geographic associations make clear the relationship 

between CMECS units and the units in the study (e.g., gravel = pebbles).

 Somewhat Certain: The relationship between the habitat descriptions in the study 

and CMECS can be inferred, but is not explicitly stated and synonyms are not 

clear.

 Not Certain: There is a connection between the habitats in the study and CMECS 

habitats, but the relationship is not clear. Connection is based on the best educated 

guess by the party coding the study.

Relationship Notes

For each source unit, specify or clarify the relationships to related CMECS units. Identify 

where clear nesting of units occurs as well as any threshold differences.

Table H1 Example of Crosswalk of FGDC (1996) Substrate Classes and Subclasses to 

CMECS, applying the CMECS metadata standard.

Cowardin 

Class/Subclass

Relationship 

to CMECS

CMECS

Class/

Subclass

Confidence Relationship Notes

Rocky Shore < Rock 

Substrate

Certain CMECS Rock 

substrate = 

Cowardin Rocky 

Shore + Rock 

Bottom.

Shore is considered 

in the CMECS 

Geoform 

Component.

Bedrock < Bedrock Certain Thresholds vary.

Rubble = Boulder Some-what 

certain

Cowardin Rubble = 

CMECS Boulder.
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Cowardin 

Class/Subclass

Relationship 

to CMECS

CMECS

Class/

Subclass

Confidence Relationship Notes

(Boulder is under 

Unconsolidated 

Substrate in 

CMECS.)

Cowardin does not 

specify size of 

boulders.

Unconsolidated 

Shore

< Unconsolidated 

Substrate

Certain CMECS 

Unconsolidated 

Substrate = 

Cowardin 

Unconsolidated

Shore 

+Unconsolidated 

Bottom.

Shore is considered 

in the CMECS 

Geoform 

Component.

Cobble/Gravel < Coarse 

Unconsolidated 

Substrates

Certain Cowardin Cobble 

Gravel does not 

include Boulders.

Sand ≈ Sand Certain Very small (0.012 

millimeters) lower 

threshold 

difference. 

Cowardin doesn’t 

recognized Muddy 

Sand as a separate 

entity.

Mud ≈ Mud Somewhat 

Certain

Cowardin doesn’t 

recognize Sandy 

Mud as a separate 

entity.

Organic ≈ Organic 

Substrate

Somewhat

Certain
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Cowardin 

Class/Subclass

Relationship 

to CMECS

CMECS

Class/

Subclass

Confidence Relationship Notes

Rock Bottom < Rock 

Substrate

Certain CMECS Rock 

Substrate = 

Cowardin Rocky 

Shore + Rock 

Bottom.

Unconsolidated 

Bottom

< Unconsolidated 

Substrate

Certain CMECS 

Unconsolidated 

Substrate = 

Cowardin 

Unconsolidated 

Shore 

+Unconsolidated 

Bottom.

Map Crosswalking Challenges and Solutions

The list below outlines some of the specific complexities encountered when crosswalking 

a mapped observation to CMECS. In general, it is best to first label polygons with the 

most closely related CMECS unit(s), and then document the relationship and uncertainty. 

However, sometimes it will be necessary to report on units that are a level or two higher 

in the CMECS classification to find common ground.

 Challenge: Units in the source map relate to more than one CMECS unit.

This occurs when the source unit concept is greater than the CMECS unit concept, 

but it also may occur when the project’s minimum mapping unit is large (allowing 

for heterogeneous polygons).

Solution: Report all of the CMECS units that are represented in the polygon.

 Challenge: The source map recognizes more detailed polygons than CMECS. 

Often local or regional map applications have specific objectives that require 

finer classification units than are described in CMECS. This is an example of the 

“less than” scenario described above.

Solution: Label the polygon with the single related CMECS type. Also, consider 

labeling each polygon with a CMECS modifier (to avoid losing the detailed 

information in the map). If it is not necessary to maintain the detailed information, 

consider lumping together adjacent polygons that represent the same CMECS 

unit, where appropriate.

 Challenge: The source map boundaries for a unit are located in a different 

place than the CMECS boundaries would be located. Most often, this occurs 
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when the source classification units and CMECS units vary in their thresholds for 

defining concepts. For example, CMECS defines the up-river boundary of an 

estuary as the head of tide, whereas FGDC (1996) defines it on the basis of 

salinity. In this case, the boundary line of the estuary on maps of these two 

classifications would not match. Here, the concept of “Estuarine” is greater in 

CMECS than in the FGDC (1996). On a map, this results in discordant 

boundaries.

Solution 1: This essentially the same as the case where the source unit is either 

broader or finer (depending on the situation) than the CMECS unit. Keep the 

existing line and follow the protocols described in the scenarios above.

Solution 2: If ancillary data that reflect the CMECS boundaries are available, 

incorporate them to modify the map to reflect the appropriate CMECS boundary.

 Challenge: The relationships between the classification units are so complex 

that it is difficult to reassemble the map units into coherent CMECS classes.

Most often, this case occurs when the relationship between the source units and 

CMECS units are based on fundamentally different concepts—and the resulting 

many-to-many relationships make rectification extremely challenging.

Solution: If the relationships between the source unit and CMECS units are manyto-many, either apply the most closely related unit higher in the CMECS 

hierarchy and then indicate the complexity, or maintain the source units and 

document the intersections using the crosswalking methodology.

 Challenge: Map units don’t allow differentiation of CMECS units, because 

the source data does not reflect the necessary CMECS thresholds. Datasets

collected with another classification scheme in mind often do not include the 

information that is needed to identify CMECS units—or the scale of the source 

data aren’t sufficiently resolved to identify CMECS units.

Solution 1: Incorporate additional ancillary data that will allow attribution (within 

limits of project objectives).

Solution 2: If ancillary data are not available and existing data do not support 

crosswalking to CMECS even at a higher level, do not proceed with the 

crosswalk. Instead, label the unit with the name from the source classification,

and indicate that there is not enough information to determine a CMECS unit.

 Challenge: The map unit has no apparent equivalent CMECS unit.

Solution: Check the CMECS modifiers to see if there is an equivalent. Check to 

see if there are units up a level or two in the CMECS classification to find 

common ground. If there is no related type higher in the hierarchy or in modifiers, 

label the unit with the name from the source classification, and indicate that there 

is no CMECS equivalent. Propose the new unit for inclusion into CMECS.
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Literature Cited

FGDC (Federal Geographic Data Committee). 1996. FGDC-STD-004. Classification of 

Wetlands and Deepwater Habitats of the United States. Reston, VA. Federal 

Geographic Data Committee.

Franz, N., R. K. Peet, and A. S. Weakley. 2008. “On the Use of Taxonomic Concepts in 

Support of Biodiversity Research and Taxonomy.” Section 5 in The New 

Taxonomy, 63–86. Systematics Association Special Volume 74. Symposium 

Proceedings. Edited by Q. D. Wheeler. Boca Raton, FL: Taylor & Francis.

http://www.bio.unc.edu/faculty/peet/pubs/Cardiff.pdf.

Madley, K., A. B. Sargent, and F. J. Sargent. 2002. Development of a System for 

Classification of Habitats in Estuarine and Marine Environments (SCHEME) for 

Florida. Report to the U.S. Environmental Protection Agency Gulf of Mexico 

Program (Grant Assistance Agreement MX-97408100). St. Petersburg, FL: Florida 

Marine Research Institute, Florida Fish and Wildlife Conservation Commission.
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Appendix I (Informative): CMECS Example Classification 

Units
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Appendix I (Informative): Example Images and Classification Units.

This appendix provides images to illustrate classifications within different Components 

of CMECS. The images are intended to show practitioners ecological units at the scale of 

human observation. These data are communicated in the form of high-resolution still 

images, but in many cases the images do not provide the resolution necessary to reveal 

some details important for full classification under a given Component. Thus, many of 

the scenes are classified only to the level of detail allowed by the image. The photographs 

are provided to show several CMECS Components, and so are not grouped in any 

specific order.

Example 1: Key West, Florida 

 Image: C. Moses

Biogeographic Setting:

Realm: Tropical Atlantic

Province: Tropical Northwestern Atlantic

Ecoregion: Floridian
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Aquatic Setting:

System: Marine 

Subsystem: Marine Nearshore

Tidal Zone: Marine Nearshore Subtidal

Water Column Component:

Water Column Layer: Marine Nearshore Lower Water Column

Salinity Regime: Euhaline Water

Temperature Regime: Warm Water

Geoform Component:

Tectonic Setting: Passive Continental Margin

Physiographic Setting: Barrier Reef

Geoform Origin: Biogenic

Level 1 Geoform: Shallow/Mesophotic Coral Reef

Level 1 Geoform Type: Patch Coral Reef

Level 2 Geoform: Lagoon

Level 2 Geoform Type: Aggregate Patch Coral Reef

Substrate Component:

Substrate Origin: Biogenic Substrate

Substrate Class: Coral Substrate

Substrate Subclass: Coral Reef Substrate

Modifier: Layering: Sand Veneer

Biotic Component

Biotic Setting: Benthic Biota

Biotic Class: Reef Biota

Biotic Subclass: Shallow/Mesophotic Coral Reef Biota

Biotic Group: Massive Coral Reef

Biotic Community: Massive Montastraea Reef
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Example 2: Narragansett Bay, Rhode Island

Image: G. Cicchetti

Biogeographic Setting:

Realm: Temperate North Atlantic

Province: Warm Temperate Northwest Atlantic

Ecoregion: Virginian

Aquatic Setting:

System: Estuarine 

Subsystem: Estuarine Coastal

Tidal Zone: Estuarine Subtidal 

Water Column Component:

Water Column Layer: Estuarine Coastal Lower Water Column

Salinity Regime: Upper Polyhaline Water

Temperature Regime: Moderate Water

Geoform Component:

Tectonic Setting: Passive Continental Margin

Physiographic Setting: Embayment/Bay

Geoform Origin: Geologic

Level 1 Geoform: Cove

Level 1 Geoform Type: Mainland Cove
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Substrate Component:

Substrate Origin: Geologic Substrate

Substrate Class: Unconsolidated Mineral Substrate

Substrate Subclass: Fine Unconsolidated Substrate

Substrate Group: Sandy Mud

Biotic Component

Biotic Setting: Benthic Biota

Biotic Class: Aquatic Vegetation Bed

Biotic Subclass: Benthic Macroalgae

Biotic Group: Filamentous Algal Bed

Biotic Community: Filamentous Aghardiella Communities

Co-occurring Element: Sheet Algal Bed: Ulva Communities
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Example 3: Punta Cana, Dominican Republic 

Image: G. Cicchetti

Biogeographic Setting:

Realm: Tropical Atlantic

Province: Tropical Northwestern Atlantic

Ecoregion: Greater Antilles

Aquatic Setting:

System: Marine 

Subsystem: Marine Nearshore

Tidal Zone: Marine Nearshore Subtidal

Water Column Component:

Water Column Layer: Marine Nearshore Lower Water Column

Salinity Regime: Euhaline Water

Temperature Regime: Very Warm Water

Geoform Component:

Tectonic Setting: Passive Continental Margin

Physiographic Setting: Continental/Island Shore Complex
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Geoform Origin: Geological/Anthropogenic

Level 1 Geoform: Shoal

Level 2 Geoform: Wreck

Substrate Component:

Substrate Origin: Anthropogenic Substrate

Substrate Class: Metal

Substrate Subclass: Metal Reef Substrate

Biotic Component

Biotic Setting: Benthic Biota

Biotic Class: Aquatic Vegetation Bed

Biotic Subclass: Benthic Macroalgae

Biotic Group: Leathery/Leafy Algal Bed

Associated Taxa: Sergeant Majors (Abudefduf saxatilis)
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Example 4: Long Beach Harbor, California

 Image: G. Cicchetti

This sediment profile image shows a vertical slice through the substrate, with the 

sediment-water interface near the top of the image. For scale, the image is 15 cm wide. 

Small burrows (marks and lines in the upper few centimeters of sediment) and a large 

burrow (larger vertical feature at left of image) are visible.

 

Biogeographic Setting:

Realm: Temperate Northern Pacific

Province: Cold Temperate Northeast Pacific
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Ecoregion: Southern California Bight

Aquatic Setting:

System: Marine 

Subsystem: Marine Nearshore

Tidal Zone: Marine Nearshore Subtidal

Water Column Component:

Water Column Layer: Marine Nearshore Lower Water Column

Salinity Regime: Euhaline Water

Temperature Regime: Cool Water

Geoform Component:

Tectonic Setting: Convergent Active Continental Margin

Physiographic Setting: Continental/Island Shore Complex

Geoform Origin: Anthropogenic

Level 1 Geoform: Harbor

Substrate Component:

Substrate Origin: Geologic Substrate

Substrate Class: Unconsolidated Mineral Substrate

Substrate Subclass: Fine Unconsolidated Substrate

Substrate Group: Sandy Mud

Biotic Component

Biotic Setting: Benthic Biota

Biotic Class: Faunal Bed

Biotic Subclass: Soft Sediment Fauna

Biotic Group: Larger Deep-Burrowing Fauna

Co-occurring Element: Small Surface-Burrowing Fauna
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Example 5: York River, Lower Chesapeake Bay, Virginia.

 Image: G. Cicchetti

Biogeographic Setting:

Realm: Temperate North Atlantic

Province: Warm Temperate Northwest Atlantic

Ecoregion: Virginian

Aquatic Setting:

System: Estuarine 

Subsystem: Estuarin Coastal

Tidal Zone: Estuarine Coastal Intertidal 

Water Column Component:

Water Column Layer: Estuarine Tidal Riverine Coastal Lower Water Column

Salinity Regime: Lower Polyhaline Watre

Temperature Regime: Moderate Water

Geoform Component:

Tectonic Setting: Passive Continental Margin

Physiographic Setting: Riverine Estuary

Geoform Origin: Geologic

Level 1 Geoform: Marsh Platform
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Level 2 Geoform: Channel

Level 2 Geoform Type: Tidal Creek

Substrate Component:

Substrate Origin: Geologic Substrate

Substrate Class: Unconsolidated Mineral Substrate

Substrate Subclass: Fine Unconsolidated Substrate

Substrate Group: Muddy Sand 

Biotic Component

Biotic Setting: Benthic Biota

Biotic Class: Emergent Wetland

Biotic Subclass: Emergent Tidal Marsh

Biotic Group: Low and Intermediate Salt Marsh

Biotic Community: Spartina alterniflora Virginian Zone Herbaceous Vegetation
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Example 6: Buzzards Bay, Massachusetts

 Image: G. Cicchetti

Biogeographic Setting:

Realm: Temperate North Atlantic

Province: Warm Temperate Northwest Atlantic

Ecoregion: Virginian

Aquatic Setting:

System: Estuarine 

Subsystem: Estuarine Coastal

Tidal Zone: Estuarine Intertidal 

Water Column Component:

Water Column Layer: Estuarine Coastal Lower Water Column

Salinity Regime: Upper Polyhaline Water

Temperature Regime: Cool Water

Geoform Component:

Tectonic Setting: Passive Continental Margin

Physiographic Setting: Embayment/Bay

Geoform Origin: Geologic

Level 1 Geoform: Cove

Level 1 Geoform Type: Mainland Cove

Level 2 Geoform: Beach
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Level 2 Geoform Type: Wave-dominated Beach

Substrate Component:

Substrate Origin: Geologic Substrate

Substrate Class: Unconsolidated Mineral Substrate

Substrate Subclass: Coarse Unconsolidated Substrate

Substrate Group: Gravel

Substrate Subgroup: Cobble

Co-occurring Element: Sand (< 20%)

Biotic Component

Biotic Setting: Benthic Biota

Biotic Class: Faunal Bed

Biotic Subclass: Attached Fauna

Biotic Group: Barnacles

Biotic Community: Semibalanus balanoides Communities

Co-occurring Element: Mobile Gastropods: Littorina littorea
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Appendix J (Informative): CMECS Development 

Participants
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Appendix J. CMECS Development Participants

The CMECS Implementation Group (Development Team) wishes to acknowledge the 

support of the many scientists, researchers and natural resource managers who 

contributed their expertise to the development of this standard. This standard, the first of 

its kind for the United States, represents many years of collaboration and cooperation. 

Without their contribution, we would not have been able to achieve our goal of 

developing this national standard.

This document is dedicated to the memory of Dail Brown, who supported CMECS 

development from the very beginning. 

The following identifies the many individuals and organizations involved in CMECS 

development.

CMECS Implementation Group (IG) Members: These contributors were responsible 

for the initial conception and overall structure of CMECS, for gathering and 

incorporating input from experts, for maintaining the effort, for generating content, and 

for the bulk of writing. They were also de facto members of the WG (see below). IG 

members were the primary authors of the document.

Rebecca J. Allee, NOAA Ocean Service, Gulf Coast Services Center

Giancarlo Cicchetti, U.S. EPA, Atlantic Ecology Division

Mark A. Finkbeiner, NOAA Ocean Service, Coastal Services Center

Kathleen L. Goodin, NatureServe

Lawrence R. Handley, USGS, National Wetlands Research Center

Christopher J. Madden, NatureServe 

Garry F. Mayer, NOAA Fisheries, Office of Habitat Conservation 

Emily Shumchenia, University of Rhode Island, Graduate School of Oceanography

Judy Soule, NatureServe

CMECS Working Group (WG) Members: These experts contributed invaluable 

content and ideas, and generated text for CMECS Sections and sections. They invested 

their time over two years, and were also the first-line reviewers of the document.

Tim Battista, NOAA Ocean Service, National Centers for Coastal Ocean Science

Mike Bradley, University of Rhode Island, Environmental Data Center

Guy R. Cochrane, USGS, Pacific Coastal & Marine Science Center

Jeffrey N. Cross, NPS, Natural Resource Program Center

Robert Diaz, Virginia Institute of Marine Science

Kathryn H. Ford, Massachusetts Division of Marine Fisheries

John King, University of Rhode Island, Graduate School of Oceanography

K.V. Koski, NOAA National Marine Fisheries Service, Habitat Conservation 

Division
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Janice C. Kurtz, U.S. EPA, Gulf Ecology Division

Steven E. Lohrenz, University of Southern Mississippi, Department of Marine 

Science (Retired)

Mike Long, U.S. EPA, Office of Environmental Information

Cliff McCreedy, NPS, Ocean and Coastal Resources Branch 

Katharine B. Miller, NOAA Fisheries, Habitat Conservation Division

Duane N. Morrison, USACE Research and Development Center, Topographic 

Engineering Center 

Christopher S. Moses, NOAA Oceanic and Atmospheric Research, International 

Activities Office 

Bryan A. Oakley, University of Rhode Island, Geosciences

Jay Odell, The Nature Conservancy

Mike Rasser, BOEMRE, Environmental Sciences Branch

Edward Rutherford, NOAA Oceanic and Atmospheric Research, Great Lakes 

Environmental Research Laboratory

Kathleen Sullivan-Sealey, University of Miami, Department of Biology

James Simons, Texas A&M University, Corpus Christi

Mark H. Stolt, University of Rhode Island, Department of Natural Resources 

Science

Saundra Upchurch, ACE Basin National Estuarine Research Reserve

Jeffrey A. Weber, Oregon Coastal Management Program, Department of Land 

Conservation and Development 

William O. Wilen, USFWS, National Wetland Inventory

Jennifer M. Wozencraft, USACE, Joint Airborne Lidar Bathymetry Technical Center 

of Expertise 

CMECS Peer Reviewers: These scientists, selected to represent a broad range of 

expertise and geography, provided critical reviews of the completed document at key 

stages of its development. Their comments led to significant changes and improvements 

to the document.

Jorge Brenner, The Nature Conservancy

Mark Costello, University of New Zealand, Leigh Marine Laboratory

Graham Edgar, University of Tasmania, Australia

Jim Maragos, USFWS (Retired)

Dave Palandro, Florida Fish and Wildlife Conservation Commission, Fish and 

Wildlife Research Institute

Mike Rasser, BOEMRE, Environmental Sciences Branch

Chris Romsos, Oregon State University, Oceanic/Atmospheric Sciences

P.G. Ross, College of William & Mary, Virginia Institute of Marine Science, Eastern 

Shore Laboratory

Kathryn Scanlon Catanach, USGS, Coastal and Marine Geology Program

Philip Schoeneberger, USDA Natural Resources Conservation Service, National Soil 

Survey

Paul Seelbach, USGS Great Lakes Science Center
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Mary Young, California State University, Monterey Bay, Seafloor Mapping Lab

Mark Zacharias, University of Victoria (Canada), Geography

Roman Zajac, University of New Haven, Dept of Biology and Environmental 

Science

CMECS Contributors: These individuals provided specific knowledge, skills, and 

input that led to important improvements to the document. Many of them contributed via 

participation in one or more of the CMECS workshops. Their thoughts and efforts were 

vital to the success of CMECS.

Danielle Bamford, The Baldwin Group

Stephen Brown, NOAA Fisheries, Office of Science and Technology

Brianne Connolly, IM Systems Group

Jennifer Dare, The Baldwin Group

Gerald Esch, NOAA Ocean Service, Coastal Services Center

Gary Greene, Moss Landing Marine Laboratories, Center for Habitat Studies 

(Retired)

Dennis Grossman, Conservation Biology Institute

Tom Hourigan, NOAA Fisheries, Office of Habitat Conservation

Rebecca Love, The Baldwin Group

Marti McGuire, NOAA Restoration Center

Kate Nielsen, NOAA Ocean Service, Management and Budget Office

Bill Stevenson, IM Systems Group

Pace Wilber, NOAA Southeast Regional Office, Habitat Division

CMECS Workshop Participants: Throughout the course of CMECS development 

many workshops were held to identify essential elements that should be considered for 

the standard. The following list identifies participants of two workshops that contributed 

to CMECS, one focusing on the Water Column Component held in January 2011, and a 

workshop addressing mapping issues held in June 2007. Some of these participants may 

also be listed above.

Water Column Workshop – January 2011 New Orleans, Louisiana

Dick Crout NOAA Data Buoy Center

Toby Garfield San Francisco State University

Rick Gould Naval Research Lab

Marian Hanisko NOAA Gulf Coast Services Center (facilitator)

John Harding Northern Gulf Institute

Darryl Keith EPA Narragansett Lab

Britta Knefelkamp University of Vechta

Dong-Shan Ko Naval Research Lab

Scott Milroy University of Southern Mississippi

Donald Olson University of Miami

Claire Paris-Limouzy University of Miami

Ed Rutherford NOAA Great Lakes Environmental Research Lab
Federal Geographic Data Committee FGDC-STD-018-2012

Coastal and Marine Ecological Classification Standard, June 2012

Appendix J (Informative): CMECS Development Participants

______________________________________________________________________________________

343

Heidi Stiller NOAA Gulf Coast Services Center (facilitator)

Saundra Upchurch ACE Basin National Estuarine Research Reserve

Mark Zacharias Ministry of Science and Universities

Mapping with the CMECS Standard Workshop – June 2007 Charleston, South Carolina

Jen Aitkin OpTech International Inc.

Drew Cary CoastalVision

Guy Cochrane U.S. Geological Survey

Scott Cross NOAA National Coastal Data Development Center

Bob Diaz Virginia Institute of Marine Science

Kass Green The Alta Vista Co.

Gary Greene Moss Landing Marine Lab

Vince Guida NOAA/NMFS Northeast Fisheries Science Center

Jeff Hyland NOAA Center for Coastal Health and Biomolecular 

Research

Dana Infante Michigan State University

Kevin Madley LEC Enviromental Consultants

Marti McGuire NOAA Restoration Center

Dave Palandro Florida Fish and Wildlife Research Institute

Maggie Payne U.S. Dept. of Agriculture

Jason Stradtner NOAA National Coastal Data Development Center

Jenny Waddell NOAA National Centers for Coastal Ocean Science

Jeff Weber Oregon Coastal Zone Management Program

Pace Wilber NOAA/NMFS Southeast Regional Office

Tony Wilbur Massachusetts Coastal Zone Management Program