FINAL REPORT

OCS Study

MMS 2010-010

ANALYSIS OF POTENTIAL BIOLOGICAL AND PHYSICAL

IMPACTS OF DREDGING ON OFFSHORE RIDGE AND SHOAL FEATURES

Prepared for:

U.S. Department of the Interior

Minerals Management Service

Leasing Division

Marine Minerals and Alternative Energy Branch
Final Report 

 

ANALYSIS OF POTENTIAL BIOLOGICAL AND PHYSICAL IMPACTS OF DREDGING 

ON OFFSHORE RIDGE AND SHOAL FEATURES 

Contract Number 1435-01-03 CT-72020 

March 2010 

Prepared for: Prepared by: 

U.S. Department of the Interior CSA International, Inc. 

Minerals Management Service 8502 SW Kansas Avenue 

Leasing Division Stuart, Florida 34997 

Marine Minerals and Alternative Energy Branch Telephone: 772-219-3000 

In cooperation with: 

Applied Coastal Research and Engineering, Inc. 

Barry A. Vittor & Associates, Inc. 

C.F. Bean, L.L.C. 

Florida Institute of Technology
MMS Study 2010-010

DISCLAIMER 

This report has been reviewed by the Minerals Management Service and approved for 

publication. Approval does not signify that the contents necessarily reflect the views and 

policies of the Service, nor does mention of trade names or commercial products constitute 

endorsement or recommendation for use.

SUGGESTED CITATION 

CSA International, Inc., Applied Coastal Research and Enginnering, Inc., Barry A. Vittor & 

Associates, Inc., C.F. Bean, L.L.C., and Florida Institute of Technology. 2009. Analysis of 

Potential Biological and Physical Impacts of Dredging on Offshore Ridge and Shoal Features. 

Prepared by CSA International, Inc. in cooperation with Applied Coastal Research and 

Engineering, Inc., Barry A. Vittor & Associates, Inc., C.F. Bean, L.L.C., and the Florida Institute 

of Technology for the U.S. Department of the Interior, Minerals Management Service, Leasing 

Division, Marine Minerals Branch, Herndon, VA. OCS Study MMS 2010-010. 160 pp. + apps. 
MMS Study 2010-010 

ACKNOWLEDGMENTS 

This project was conceived and funded by the U.S. Department of the Interior, Minerals 

Management Service (MMS). Ms. Colleen Finnegan provided assistance and direction during 

the project as the MMS Contracting Officer’s Technical Representative. Ms. Debra Bridge 

served as the MMS Contracting Officer. We gratefully acknowledge their guidance in the 

conduct of this project. We also thank Ms. Kristen Metzger of CSA International, Inc. for 

assistance in literature and data collection. Ms. Kim Dunleavy and Ms. Melody Powell provided 

editorial assistance, and Ms. Karen Stokesbury supervised CSA International, Inc. support staff 

during production of the report. 
MMS Study 2010-010
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EXECUTIVE SUMMARY 

The Minerals Management Service (MMS) is responsible for managing exploration and 

development of mineral resources on submerged Federal Outer Continental Shelf (OCS) lands 

in an environmentally sound and safe manner, including sand deposits. The OCS contains 

large sand deposits that are expected to serve as long-term sources of borrow material for 

beach nourishment and coastal restoration projects. Potential for exploitation of these 

resources has grown rapidly in the last several years with identification of suitable sand 

resource areas in some OCS regions. Demand for high quality sand suitable for beach 

nourishment, coastal protection, and other public and private projects is anticipated to increase 

during coming years. 

Coastal jurisdictions recently have become more interested in sand resources seaward of State 

waters for several reasons. Onshore sources of suitable sand that were once abundant are 

now becoming scarce due to deposit depletion, competing uses, and urban development. For 

large nourishment projects, transporting sand from nearshore areas often is far more 

economical than trucking sand from upland sources. Like onshore sources, nearshore sand 

resources often are limited, diminishing in supply, and/or polluted, necessitating the need for 

alternative deposits that exist farther offshore. Using offshore deposits provides the important 

benefit of adding sand to the beach/nearshore system, rather than simply moving sand from one 

part of the system (nearshore) to another (beach). Furthermore, sand resources in Federal 

waters may be environmentally preferable due to concerns that extraction of large quantities of 

sand and gravel from nearshore sites can change the bathymetry of an area and result in 

modifications to existing physical oceanographic conditions. 

Offshore sand resources have become an important component of the U.S. Army Corps of 

Engineers (USACE) projects that focused on beach nourishment for coastal erosion control. 

Shelf sand ridges are common along the Atlantic and Gulf coasts of the United States and serve 

as good potential sources of suitable sand for beach nourishment projects. Considerable 

variability in geomorphic and sedimentologic characteristics exists as a function of sediment 

source, and dominant wave and current processes contribute to the suitability of individual sand 

ridges as a sand source. 

The objective of this study was to examine and evaluate the potential biological and physical 

effects of offshore dredging within the ridge and swale features on the Federal OCS and to 

suggest engineering options and mitigation measures that can be implemented to avoid 

potential deleterious impacts, while allowing for the selective removal of needed volumes of 

sand for nearby beach projects. Research Planning, Inc. et al. (2001) identified several 

information gaps with respect to physical and biological effects of dredging on sand shoals. The 

authors framed these gaps as questions, four of which provided much of the impetus for the 

present study. The questions, in the order given by Research Planning, Inc. et al. (2001), are 

as follows: 

 What is the use and role of sand ridges and shoals as potential essential fish habitat (EFH) 

by migrating or resident fish? 

 Is there a preferred manner to remove sand from a shoal/ridge feature to maximize their use 

and maintain the integrity of the feature? 

 Are there benthic biological differences that run longitudinally along the ridge and shoal 

features that may affect the proposed sampling design and require further stratification? 
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 Are there procedures to dredge shoal and ridge features that will minimize ecological 

impacts and/or speed recovery, such as dredging completely one specific shoal or ridge and 

leaving adjacent features untouched vs. dredging a small amount of sand from each shoal 

or ridge feature, or dredging in strips leaving undisturbed areas that act as local sources of 

recruitment and allow recruitment from older life stages, as supported by the work 

conducted by Whitlatch et al. (1998)? 

Although inter-related, these questions do not follow a strict logical sequence with one another. 

For this report, connections between questions related to physical effects and their expected 

biological response are made when possible. The first and third questions pertain to spatial 

distribution of invertebrate assemblages and habitat use by fishes. The second and fourth 

questions are concerned with minimizing direct physical impacts to shoals in ways that facilitate 

biological recovery. A primary goal of this report is to link physical effects of dredging to direct 

and indirect biological effects and suggest ways to reduce impacts and speed recovery while 

still effectively mining sand resources. Potential dredging impacts outside of the study area 

model domain were not evaluated as part of this project (e.g. potential impacts at the shoreline). 

However, previous MMS studies have reported on these potential impacts (e.g., Byrnes et al., 

2004; Maa et al., 2004; Kelley et al., 2004). 

TECHNICAL APPROACH 

To accomplish the study objective, a technical approach consisting of a series of steps was 

developed to compile and analyze technical information required to answer the aforementioned 

study questions. The first step was to collect pertinent published and unpublished results on 

ridges, shoals, and swales from author libraries, other private and public libraries, and internet 

websites (Section 1.1). After compiling baseline information on offshore shoal fields, a review 

of dredging procedures for sand mining at these sites was summarized for cutterhead dredges, 

hopper dredges, and other offshore dredging equipment and techniques as described in 

Section 2.0. Before considering potential impacts of offshore sand mining on physical 

processes and biological communities at offshore sites, a review of physical impact producing 

factors associated with sand mining within the study area was completed (Section 3.0). 

Potential concerns regarding biological community impacts were analyzed by reviewing 

pertinent studies to ascertain the role of ridges, shoals, and swales as Essential Fish Habitat 

(EFH) using a cross-shelf analysis framework. The cross-shelf approach was chosen because 

EFH is broadly defined as "those waters and substrate necessary to fish for spawning, breeding, 

feeding or growth to maturity," which covers the full spectrum of life histories and habitats rather 

than only ridges, shoals, and swales. Furthermore, a review of pertinent studies to ascertain 

patterns of benthic biological differences across ridges, shoals, and swales was conducted. 

The results of these analyses are presented in Section 4.0. 

After pertinent background information was compiled and analyzed, existing knowledge of 

borrow site geometries was contemplated relative to environmental and economic 

considerations. Dredging equipment and techniques were evaluated, and sand mining 

scenarios were designed taking into account the natural, long-term evolution of the shoal. 

Potential shoal dredging scenarios specified by the MMS were considered when developing the 

following sand mining scenarios for simulating shoal changes and potential responses: 1) 

dredging a hole over a designated area on the shoal; 2) dredging the leading edge of a shoal; 3) 

dredging the trailing edge of a shoal; and 4) dredging in a striped pattern to facilitate recruitment 

of benthic invertebrates into dredged areas (Section 5.1). 
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Numerical modeling was completed to provide baseline information regarding potential physical 

impacts, as well as to evaluate potential physical impact producing factors (i.e., sediment 

removal, suspension/dispersion [turbidity], deposition [changes in sediment thickness and grain 

size], and other potential physical disturbances from dredging and positioning equipment) 

concerning potential biological impacts of dredging offshore ridge and shoal features. Emphasis 

was placed on estimating the physical impact producing factors associated with the selected 

dredging scenarios that could be applicable to evaluating near-field and far-field, and short-term 

and long-term biological impacts (Section 5.2). 

The results of simulated offshore sand mining scenarios were then analyzed relative to potential 

impacts on biological communities. Underlying questions regarding potential biological and 

physical impacts of sand mining at offshore shoals were answered, and dredging scenario 

alternatives were reported within the context of minimizing ecological impacts and/or enhancing 

shoal recovery (Section 6.0). Finally, recommendations for dredging options and mitigation 

measures were provided in Section 7.0. 

DREDGING AT RIDGES AND SHOALS 

There are two types of dredges commonly used in the removal of sediment from ridges, shoals, 

and other types of offshore borrow areas -- hydraulic cutterhead dredges and trailing suction 

hopper dredges. Two other types of dredges that may used on rare occasions are the dustpan 

dredge and the Punaise (or “thumbtack”). 

Hydraulic cutterhead dredges incorporate the use of a cutterhead near the suction mouth to 

dislodge the excavated material from the seafloor and assist in the slurrification of the sediment 

for removal by the suction mouth of the dredge. Dredged material is transported up the suction 

mouth and propelled away from the dredge via a centrifugal dredge pump. Sediment is 

transported through a pipeline to the destination, where it is either shaped into the desired fill 

dimensions or stockpiled for further rehandling. 

Hopper dredges are commonly used in offshore conditions where exposure to sea conditions 

can adversely impact productivity and efficiency of other types of dredges. They often are 

configured like a ship with a cargo hold designed for dredged material. They are equipped with 

one to three dragarms, which are pipe structures suspended down the side of the hull to the 

seafloor. Dredged material is removed from the bottom through the dragarms and placed in the 

cargo hold of the vessel for transport. The vessel transports the material to a remote location 

for discharge through the bottom of the hull or for discharge from the hull through a pipeline. 

The dustpan dredge is ideal for excavation of granular sediment. Dustpan technology relies on 

agitation of the bottom sediments through the use of water jets near the suction head to 

excavate and remove sand from the seabed. This technology works well in sediments that are 

relatively clean, free from silt, mud, and shell or shell fragments. High velocity water jets are 

injected into the sediment along the top or bottom of the dustpan head. As the dredge pulls 

itself forward, the jets collapse, slurrify, and remove the sediments that fall in front of the suction 

mouth. 

The Punaise, or “thumbtack,” is used to mine sand in either the offshore or inland environments, 

but has the limitation that significant banks of sand are required to make it a productive device. 

The Punaise consists of a watertight housing containing the dredge pump, motor, and ballast 

tanks and is connected to the shore station via an umbilical that comprises control connections, 

power supply, and a slurry discharge line. Once positioned at the appropriate location, the 
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ballast tanks are filled, the Punaise settles to the bottom, and water jet nozzles are then 

activated, which allows the vertical support to settle into the sand bottom so the dredging 

process can begin. While in operation, the Punaise rests on the bottom of the seabed and 

excavates sediment by means of hydraulic erosion and agitation. 

Several techniques that can be used in dredging sand ridges and shoals are the following: 

 Deep mining (glory hole) has been a method of mining sand in the offshore environment in 

the past that would yield the maximum productivity and cost efficiency for removal. This 

technique simply involves placing the suction mouth of the dredge, with or without an 

agitation device like a cutter, on the seabed and continuing to lower the suction depth until 

the borrow pit yield diminishes. When the sand quits flowing to the suction mouth, the 

dredge is advanced or moved to a new location. 

 Thin layer removal is often required when there is only a thin layer of suitable material (less 

than 1.8 to 2.4 m thick) available for a project. There are numerous implications associated 

with thin layer availability and removal. The thin layer could be overlain and underlain by 

unsuitable material. Unsuitable material could be defined as a very fine silty mud or a layer 

of very rocky sediments, neither of which might be considered as suitable for the 

renourishment project. 

 Aggressive, maximum spillage is a method of removal that is common when the sediment 

transportation capability of the dredge is sufficient to permit a high percentage concentration 

by volume of sediment in the slurry. A dredge can move through a bank of material with a 

high percent of spillage, 40% to 60%, and maintain a high production and lower cost. 

 Slow, minimum spillage is a method that results in a spillage factor as low as 15% to 20% 

with a much lower productivity and higher cost implications. This method may be chosen 

when available borrow material is limited and a more complete evacuation of the borrow 

area may be necessary to achieve the necessary quantities. 

IMPACT PRODUCING FACTORS 

Dredging at offshore shoals and ridges creates several physical factors that will produce 

impacts on biological resources associated with these features. As general categories, these 

physical factors are 

 Sediment removal; 

 Turbidity; and 

 Sediment deposition. 

Removal of sediments from borrow sites can alter seabed topography, creating pits that may 

either refill rapidly or potentially cause detrimental impacts for extended periods of time. 

Immediate losses of infaunal biomass occur and these can affect adjacent areas through food 

web disturbances at poorly known time scales. If borrow pits are deep, current velocity is 

reduced at the bottom, which can lead to deposition of fine particulate matter, and in turn, a 

biological assemblage can be established that is much different in composition than the original. 

Long-term physical and biological impacts could occur if dredging significantly changes the 

physiography of shoals. 

Dredging causes suspension of sediments, which increases turbidity over the bottom. Although 

turbidity plumes associated with dredging often are short lived and may affect relatively small 

areas, resuspension and redispersion of dredged sediments by subsequent currents and waves 

can propagate dredge-related turbidity for extended periods after dredging ends. For sand 
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dredging from offshore shoals for beach nourishment, turbidity plumes are typically minimal, and 

consequently turbidity effects are expected to be less important in unprotected offshore areas 

because sand settles more rapidly than clay and silt and offshore shoals tend to be coarser than 

inshore deposits. In addition, the open ocean environment provides more dynamic physical 

oceanographic conditions, which minimize settling effects. 

Offshore organisms are adapted to sediment transport processes, which create scouring, 

natural turbidity, and sedimentation under normal conditions. Biological responses to turbidity 

depend on all of these physical factors, coupled with the type of organism, geographic locations, 

and the time of year. Turbidity from dredging can affect food availability for benthic organisms. 

Changes in light penetration and wavelengths due to turbidity can affect visibility and may be 

detrimental or beneficial, depending in part on whether an organism is predator or prey. 

Turbidity can interfere with food gathering processes of filter feeders and organisms that feed by 

sight as a result of inundation with non-nutritive particles. In addition to altered feeding rates, 

other biological responses to turbidity include reduced hatching success, slowed growth, 

abnormal development, tissue abrasion, and increased mortality. Suspension and dispersion 

processes uncover and displace benthic organisms, temporarily providing extra food for 

bottom-feeding species. 

Suspended sediments settle and are deposited nearby dredged offshore sand borrow sites. 

The extent of deposition and boundaries of biological impact are dependent on the type and 

amount of suspended sediments and physical oceanographic characteristics of the area. 

Deposition of sediments can suffocate and bury benthic biota, although some mobile soft 

bottom organisms are able to migrate vertically to the new surface. Furthermore, sediment 

deposition can inhibit larvae of numerous invertebrate species that need hard surfaces to settle 

and develop. 

BIOLOGICAL RESOURCES 

Previous reviews concerning potential impacts of offshore sand mining (Research Planning, Inc. 

et al., 2001) suggested further investigation into the status of sand shoals as EFH for federally 

managed species and their prey. They found very little data available on the ecological function 

of sand shoals by fishes or invertebrates. Since the Research Planning, Inc. et al. (2001) report 

was issued, information regarding fish utilization of sand shoals in the Mid-Atlantic Bight region 

has emerged, particularly in the region offshore Delaware, Maryland, and New Jersey. Data 

gathered from individual shoals confirmed that a diverse assemblage of demersal and pelagic 

fishes associate with regional sand shoals and potentially use these shoals for feeding, 

spawning, and growing to maturity, often during migrations across the shelf in the fall and 

spring. 

Benthic invertebrates that inhabit sand shoals provide structural fish habitat (worm tubes, 

burrows, and depressions) as well as a forage base for demersal feeders. Invertebrate species 

richness is lower on the shoals compared to surrounding areas. Field studies of adult fish 

species collected with trawl and gill nets confirms that benthic feeders such as skates, scup, 

drums, searobins, flounders, and black seabass occur around shoals and adjacent sand bottom 

areas. These species are behaviorally and morphologically adapted for benthic feeding in 

sedimentary environments. 

Pelagic species such as bay anchovy, Atlantic menhaden, Atlantic mackerel, butterfish, and 

striped bass were also documented to associate with shoals. It is possible that hydrodynamic 

effects of the shoal features aid in water column feeding by these species. Spawning by fishes 
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in the vicinity of sand shoals can be inferred from the presence of eggs and early stage larvae. 

Plankton net samples revealed that anchovy, Atlantic menhaden, Atlantic mackerel, and 

searobins spawn in the vicinity of shoals in the Mid-Atlantic Bight. Shoals may also be 

important as juvenile habitat for species that utilize both inshore estuarine habitats and the 

nearshore shelf as nursery areas. The precise nature of any obligate association of demersal or 

pelagic fishes with shoals is not known, but it appears that many fish species rely on shoal 

features as a part of a broader, cross-shelf habitat continuum within which they complete their 

life cycles. EFH evaluations should be made to avoid or minimize any adverse physical and 

biological effects produced by sand dredging on shoals in OCS waters. 

MODELING 

Geomorphologic changes associated with potential sand mining scenarios on shoals offshore 

Fenwick Island, Maryland, were simulated using three interrelated numerical models. Tidal 

hydrodynamic, wave process, and sediment transport pattern models were coupled to assess 

the morphologic response of offshore sand shoals to various “dredging” scenarios in support of 

future beach nourishment requirements. The excavation scenarios simulated were 

 Dredging a hole over a designated area on the shoal; 

 Dredging the leading edge of a shoal; 

 Dredging the trailing edge of a shoal; and 

 Dredging in a striped pattern to facilitate recruitment of benthic invertebrates into dredged 

areas. 

Tidal hydrodynamics for the continental shelf and nearshore areas offshore the Delmarva 

Peninsula were modeled using the Advanced Circulation Model for Oceanic Coastal and 

Estuarine Waters (ADCIRC). ADCIRC is a two-dimensional (2-D), depth-integrated circulation 

model. Model prediction of tidal amplitude and phase offshore Ocean City Inlet matched well 

with measured data from a NOAA tide gage. Average tidal flow velocities observed in the study 

area are on the order of 0.05 m/s. The direction of flow is observed to be north/northeast on a 

flooding tide and south/southwest on the ebbing tide. 

With such small tidal velocities so far offshore, incident wave energy played a primary role in 

sediment movement and morphology change at the offshore shoals. Nearshore wave heights 

and directions across Weaver Shoal, Isle of Wight Shoal, and Shoal A were estimated using the 

USACE STeady-state spectral WAVE model (STWAVE). STWAVE is a steady state, spectral 

wave transformation model that uses 2-D (frequency and direction versus energy) spectra as 

input to simulate wave refraction and shoaling induced by changes in bathymetry and by wave 

interactions with currents. Hindcast wave data from the USACE Wave Information Study (WIS) 

were used as input to the wave model. 

The primary purpose for ADCIRC and STWAVE modeling was to provide forcing for the 

CMS-M2D model so that shoal morphology change could be examined. CMS-M2D is a 2-D, 

depth-integrated, finite-difference hydrodynamic model that has the option of including 

morphology change estimates through the use of a sediment continuity equation for updating 

changes in bathymetry. Full coupling with an external wave model (STWAVE in this case) is 

possible, with the wave model providing radiation and shear stresses to CMS-M2D. In return, 

the hydrodynamic and morphology changes are passed back to the wave model. 

Bathymetric change at and adjacent to the shoals in response to various “dredging” geometries 

was of particular interest. In addition to a baseline scenario for each of the shoals, three 
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dredging geometries for Weaver and Isle of Wight shoals were simulated, along with two 

dredging scenarios at Shoal A. Each of these geometries was evaluated under a 3-day storm 

from the northeast and a 3-day storm from the east. Results from the Baseline scenario 

provided insight to the current trends in shoal morphology and migration. Simulations indicate 

dominant sand transport from northeast to southwest and south, where sand is eroded from 

shoal crests and deposited on the leading edge of the shoal. 

Modeling results illustrated that a dredged portion of a shoal will not simply fill because there is 

a depression present. If dredging is performed on a portion of a shoal that is not active under 

present conditions, there will be a lack of sand availability to replenish the sand removed during 

borrow site excavation. Imposed storm conditions will not be effective at mobilizing significant 

amounts of sand in the excavated area, and larger-scale shelf processes and major storm 

events may be the only mechanisms by which the “dredged” areas will be filled. Material 

removed from active areas of a shoal will be replenished more quickly by normal wave 

conditions at the site. Shallow shoal crests, like Isle of Wight Shoal, and the leading edge of all 

three shoals are noted as the active areas of erosion/deposition. These active transport and 

deposition areas will recover to original conditions more rapidly than inactive portions of shoals. 

The striped pattern dredging scenario indicated that trenches in excavated areas fill almost 

uniformly along the length of the “dredged” area. While deposition was greater along the 

northern edges of excavated trenches, each trough showed deposition for most of its length. 

Deposition in the center and southern portions of the “dredged” region is a result of sand 

erosion from undisturbed areas and into adjacent low areas. In terms of timely and uniform 

recovery of a shoal from borrow site dredging, the striped pattern of sediment removal offers 

great promise. 

QUESTIONS AND ALTERNATIVES 

Based on geological models of shoal formation, there does not appear to be a mechanism 

supporting the idea that the structural integrity of a feature will “deflate” or “unravel” when 

subject to repeated dredging. As long as a seafloor irregularity remains upon which to reform the 

ridge, dominant shelf processes will construct these features as described by shelf ridge process 

models.

For the dredging scenarios examined, the most desirable location or subarea (crest, leading 

edge, or trailing edge) of a shoal for dredging is the leading edge from a physical standpoint. 

This is primarily due to net long-term deposition and faster infilling rates of dredged areas. The 

crest would be a second choice, followed by the trailing edge. In terms of the dredging removal 

method (cut, slice, or striped pattern) the striped pattern showed the most promise. Shallow 

striped areas in the modeling scenarios recovered more rapidly toward pre-dredging levels. 

Some benthic biological differences are expected to occur along the longitudinal axis of a shoal 

reflecting physical habitat differences that occur across the feature. The leading edge, crest, 

and trailing edge may support assemblages that are partially distinct in terms of the occurrence 

of certain populations. Although they are to some extent variable, these assemblages are 

expected to show general consistency of population composition longitudinally. There are 

differences in community patterns comparing the current-facing and lee sides of shoals, in 

particular the occurrence of aggregations of tube-building populations on the lee side. Benthic 

biological differences among shoal subareas suggest that additional stratification should be 

considered when designing dredging projects and monitoring programs. 
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Targeting shoal and ridge locations that may be less susceptible to prolonged physical alteration 

assumes in part that the nature of biological recovery, including the speed of colonization and 

benthic assemblage composition, will depend in large measure on the physical characteristics of 

a site after dredging. There are other system drivers that may influence differing measures of 

biological recovery including variability in supply, transport, and settlement of larvae for some 

species on a spatial scale that greatly exceeds the shoal area itself. 

RECOMMENDATIONS 

For a given dredging and beach nourishment interval, it is advisable to remove only a portion of 

a particular ridge or shoal. For a given ridge or shoal, project elements such as target site 

location, dredging depth, and excavation patterns may be designed to avoid persistent physical 

alteration after cessation of dredging. Recommendations for selection of target sites and 

dredging methods to avoid or minimize adverse physical consequences may include: 

 Extracting sand from a depocenter, leading edge, or downdrift margin of a shoal, to avoid 

interrupting natural shoal migration and potentially reduce the time required for site refilling; 

 Avoid dredging in erosional areas that source downdrift depocenters, which also may be 

slow to refill after dredging; 

 Shallow dredging over large areas rather than excavating small but deep pits may be 

preferred depending on the infaunal charactersitics; 

 Dredging in a striped pattern to leave sediment sources adjacent to and interspersed 

throughout target areas, leading to a more uniformly distributed infilling process; and 

 Excavation should occur on shoal crests and higher areas of the leading edge rather than 

lower areas of the shoals because of greater exposure to wave-generated turbulence and 

greater sediment mobility, which potentially results in more rapid sediment reworking and 

site infilling, and likely would induce the benthic community to recover more rapidly. 

Shoals and ridges serve as a benthic nursery area, refuge, and feeding sites for a variety of 

ecologically important and commercially and recreationally harvested fish and invertebrate 

resources. In assessing the consequences of sand mining on EFH of shoal and ridge systems 

of the Federal OCS, a thorough analysis should include an assessment of how different 

techniques of dredging could affect fishery resources and site-specific investigations of physical 

environmental processes in addition to species life history information and patterns of habitat 

use. EFH analysis also should include assessment of the level of importance of 

geomorphological and hydrodynamic flow regimes with respect to fishery resources. 
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TABLE OF CONTENTS 

Page 

1.0 INTRODUCTION ...................................................................................................................1

1.1 OFFSHORE RIDGES AND SHOALS............................................................................1

1.2 STUDY OBJECTIVE AND QUESTIONS.......................................................................6

1.3 STUDY DESIGN............................................................................................................8

1.3.1 Technical Approach ............................................................................................8

1.3.2 Study Area ..........................................................................................................9

1.4 DOCUMENT ORGANIZATION....................................................................................13

2.0 OFFSHORE DREDGING PROCEDURES AT RIDGES AND SHOALS – 

OFFSHORE DREDGING EQUIPMENT AND TECHNIQUES.............................................17

2.1 CUTTERHEAD DREDGES .........................................................................................17

2.1.1 Dredging Equipment .........................................................................................17

2.1.2 Global Positioning System (GPS) .....................................................................20

2.1.3 Dredging Techniques in Sand Ridges and Shoals............................................21

2.1.4 Dredged Material Transportation and Pipelines................................................22

2.1.5 Turbidity Sources During Dredging...................................................................24

2.2 HOPPER DREDGES...................................................................................................24

2.2.1 Dredging Equipment .........................................................................................25

2.2.2 Hopper Dredge Loading....................................................................................26

2.2.3 Pump Ashore Operations..................................................................................27

2.3 OTHER OFFSHORE DREDGING EQUIPMENT AND TECHNIQUES .......................28

2.3.1 Dustpan Dredges ..............................................................................................28

2.3.2 Punaise 29

3.0 PHYSICAL IMPACT PRODUCING FACTORS ASSOCIATED WITH 

SAND MINING ON SHOALS OFFSHORE MARYLAND....................................................31

3.1 EXCAVATION QUANTITY AND SEDIMENT REMOVAL............................................31

3.1.1 Sediment Availability.........................................................................................32

3.1.2 Sediment Removal............................................................................................33

3.2 SEDIMENT SUSPENSION/DISPERSION (TURBIDITY) ............................................36

3.3 SEDIMENT DEPOSITION...........................................................................................38

4.0 EVALUATION OF BIOLOGICAL RESOURCES ASSOCIATED WITH SHOALS 

OFFSHORE OF THE MID-ATLANTIC BIGHT....................................................................39

4.1 INVERTEBRATES.......................................................................................................39

4.2 FISHES........................................................................................................................43

4.2.1 Fishes and Life Stages Associated with Sand Shoals ......................................44

4.2.2 Eggs and Larvae...............................................................................................45

4.2.3 Juveniles and Adults .........................................................................................51

4.3 INTERACTIONS BETWEEN INVERTEBRATES AND FISHES..................................53

4.3.1 Trophic Relationships........................................................................................53

4.3.2 Habitat Engineers..............................................................................................54

4.3.3 Bioturbation.......................................................................................................55

4.4 RECOLONIZATION.....................................................................................................56

4.4.1 Settlement Patterns...........................................................................................56
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TABLE OF CONTENTS 

(Continued) 

Page 

4.4.2 Recovery Dynamics ..........................................................................................57

4.5 SHOALS AS ESSENTIAL FISH HABITAT (EFH)........................................................60

4.5.1 Management and Species Categories..............................................................60

4.5.2 Functional Values..............................................................................................62

4.6 SHOAL HABITATS IN COMPARISON TO OTHER CROSS-SHELF 

FEATURES .................................................................................................................65

4.6.1 Characterizing Cross-shelf Gradients and Habitats..........................................65

4.6.2 Cross-shelf Patterns of Habitat Use Among Some Demersal and 

Pelagic Species.................................................................................................66

4.6.3 Cross-shelf Distributional Patterns of Demersal and Pelagic Species..............70

5.0 SELECTION OF ALTERNATIVE SCENARIOS AND SIMULATION OF PHYSICAL 

PROCESSES.......................................................................................................................75

5.1 PHYSICAL CONSIDERATIONS..................................................................................75

5.1.1 Specific Shoal Characteristics...........................................................................75

5.1.2 Alternative Excavation Scenarios......................................................................80

5.2 NEARSHORE HYDRODYNAMICS, WAVE PROPAGATION, AND 

MORPHOLOGICAL MODELING.................................................................................86

5.2.1 Overview of Regional Hydrodynamics ..............................................................86

5.2.2 Overview of Regional Wave Conditions............................................................88

5.2.3 Hydrodynamic Modeling....................................................................................92

5.2.4 Wave Modeling .................................................................................................97

5.2.5 Nearshore Sedimentation and Borrow Site Infilling.........................................105

5.2.6 Discussion.......................................................................................................115

6.0 QUESTIONS AND ALTERNATIVES FOR OPTIMIZING PHYSICAL-BIOLOGICAL 

IMPACTS OF SHOAL DREDGING...................................................................................121

6.1 IS THERE A PREFERRED MANNER TO REMOVE SAND FROM A 

SHOAL/RIDGE FEATURE TO MAXIMIZE THEIR USE AND MAINTAIN THE 

INTEGRITY OF THE FEATURE? .............................................................................121

6.2 ARE THERE BENTHIC BIOLOGICAL DIFFERENCES THAT RUN 

LONGITUDINALLY ALONG THE RIDGE AND SHOAL FEATURES SUCH 

THAT DREDGING OPERATIONS SHOULD BE TAILORED TO AVOID 

CERTAIN AREAS?....................................................................................................121

6.3 ARE THERE PROCEDURES TO DREDGE SHOAL AND RIDGE FEATURES 

THAT WILL MINIMIZE ECOLOGICAL IMPACTS AND/OR SPEED 

RECOVERY? ............................................................................................................122

6.3.1 Dredging a Hole Over a Restricted Area on the Crest of a Shoal, 

Equivalent to Standard Approaches to Dredging a Shoal...............................124

6.3.2 Dredging the Leading Edge of a Shoal ...........................................................126

6.3.3 Dredging the Trailing Edge of a Shoal ............................................................127

6.3.4 Dredging in a Striped Pattern to Facilitate Recruitment of Benthic 

Invertebrates into Dredged Areas ...................................................................127
MMS Study 2010-010 

iii 

TABLE OF CONTENTS 

(Continued) 

Page 

7.0 RECOMMENDATIONS FOR ENGINEERING OPTIONS AND MITIGATION 

MEASURES.......................................................................................................................131

7.1 SPATIAL SCOPE OF POTENTIAL CONSEQUENCES............................................131

7.2 IMPACTS AT INDIVIDUAL RIDGES AND SHOALS.................................................132

7.3 RECOMMENDATIONS FOR IMPROVING EFH MANAGEMENT ............................134

8.0 LITERATURE CITED ........................................................................................................137 
MMS Study 2010-010 

iv 
MMS Study 2010-010

v 

LIST OF FIGURES 

Figure Page 

 1.1. Illustration of ridge and swale topography on the mid-Atlantic continental 

shelf, Maryland, and Delaware. ................................................................................2

 1.2. Illustration of ridge and swale topography on the west Florida continental 

shelf, seaward of Pensacola Pass............................................................................3

 1.3. Schematic diagram of ridge classes as presented in Snedden and 

Dalrymple (1999). The precursor in the case of the Class I and II ridges is a 

pre-existing bathymetric feature, sometimes associated with a shoreline or 

inlet, which provides the focal point for the ridge growth and migration via 

the Huthnance process. Subsequently, this precursor may be removed or 

reduced in size through current erosion and ridge migration. Accretion on 

the landward side of the juvenile ridge (Class I) is largely induced by fairweather wave transport from the ridge crest and is not expected to occur in 

ridges developed in deeper water, as with Classes II and III. New ridge 

sand is primarily deposited in shelf waters by combined flows associated 

with storms................................................................................................................5

 1.4. Flowchart of technical approach. ..............................................................................7

 1.5. U.S. mid-Atlantic coast, showing the location of Ocean City, Md., and 

surrounding states. .................................................................................................10

 1.6. Bathymetric map of the study area, documenting three offshore shoals 

evaluated for potential sand mining for Ocean City, Md., beach 

nourishment. ...........................................................................................................11

 1.7. Weaver Shoal sand resource acceptability classification by USACE (2008)..........14

 1.8. Isle of Wight Shoal sand resource acceptability classification by USACE 

(2008)......................................................................................................................15

 1.9. Shoal A sand resource acceptability classification by USACE (2008)....................16

 3.1. Areal extents for selected dredging scenarios for each shoal relative to 

seafloor changes recorded between 1975/1978 and 2002.....................................35

 4.1. Approximate locations of station groups (A through G) resolved from cluster 

analysis of grab sample composition across 1998-1999 stations in the area 

of Fenwick Shoal (Original data, base map, and station locations adapted 

from Virginia Institute of Marine Science, 2000). ....................................................41

 4.2. Overview of shoal sample areas.............................................................................46
MMS Study 2010-010 

vi 

LIST OF FIGURES 

(Continued) 

Figure Page 

 4.3. Estimates of summer flounder (Paralichthys dentatus) cross-shelf 

distribution and relative abundance ranks of adults during summer and 

winter, stratified according to habitat and physical cross-shelf gradient. 

Solid bars represent abundance ranks based on high, low, and rare or no 

occurrence derived from literature cited in text. Shaded cells reflect habitats 

that do not occur within certain cross-shelf gradients. ............................................68

 4.4. Estimates of windowpane flounder (Scophthalmus aquosus) cross-shelf 

distribution and relative abundance ranks of larvae and early stage juveniles 

during summer and winter, stratified according to habitat and physical 

cross-shelf gradient. Solid bars represent abundance ranks based on high, 

low, and rare or no occurrence derived from literature cited in text. Shaded 

cells reflect habitats that do not occur within certain cross-shelf gradients. ...........69

 4.5. Estimates of bay anchovy (Anchoa mitchilli) cross-shelf distribution and 

relative abundance ranks of larvae and early stage juveniles during summer 

and winter, stratified according to habitat and physical cross-shelf gradient. 

Solid bars represent abundance ranks based on high, low, and rare or no 

occurrence derived from literature cited in text. Shaded cells reflect habitats 

that do not occur within certain cross-shelf gradients. ............................................71

 4.6. Estimates of striped bass (Morone saxatilis) cross-shelf distribution and 

relative abundance ranks of adults during summer and winter, stratified 

according to habitat and physical cross-shelf gradient. Solid bars represent 

abundance ranks based on high, low, and rare or no occurrence derived 

from literature cited in text. Shaded cells reflect habitats that do not occur 

within certain cross-shelf gradients.........................................................................72

 5.1. Bathymetric map of the study area documenting three offshore shoals 

evaluated for potential sand mining for Ocean City, Md., beach 

nourishment. ...........................................................................................................76

 5.2. Weaver Shoal sand resource acceptability classification by USACE (2008)..........77

 5.3. Isle of Wight Shoal sand resource acceptability classification by USACE 

(2008)......................................................................................................................78

 5.4. Shoal A sand resource acceptability classification by USACE (2008)....................79

 5.5. Areal extents of modeled dredging scenarios for each shoal. ................................81

 5.6. Weaver Shoal – hole excavation on shoal crest. ....................................................82
MMS Study 2010-010

vii 

LIST OF FIGURES 

(Continued) 

Figure Page 

 5.7. Weaver Shoal – striped area excavation on shoal crest.........................................82

 5.8. Weaver Shoal – leading edge excavation (slice). ...................................................83

 5.9. Isle of Wight Shoal – hole excavation on shoal crest..............................................83

 5.10. Isle of Wight Shoal – striped area excavation on shoal crest. ................................84

 5.11. Isle of Wight Shoal – trailing edge excavation (slice)..............................................84

 5.12. Shoal A – trailing edge excavation (hole). ..............................................................85

 5.13. Shoal A – striped area excavation on trailing edge of shoal. ..................................85

 5.14. Typical semi-diurnal tidal signal from NOAA water level recording Station 

8570280 at the Ocean City Fishing Pier, Md. .........................................................87

 5.15. WIS stations in the study region are shown with yellow markers. USACE 

Wave Gage MD002 and NDBC Buoy 44009 are shown in green. .........................89

 5.16. Wave height and energy roses for WIS Stations 161 and 163. ..............................90

 5.17. Wave height comparison between WIS Station 161 and NDBC Buoy 44009 

for 1990. The top panel illustrates a time series of wave heights for each 

station, while the bottom panel shows the difference between WIS and 

NDBC results as WIS prediction - buoy measurement. ..........................................92

 5.18. ADCIRC model domain for the mid-Atlantic coast. The offshore boundary is 

shown in blue, land boundaries are brown, and islands are green.........................93

 5.19. Detail of the ADCIRC model domain focused on Ocean City, Md. 

Bathymetry contours are shown in color, overlain with model mesh for this 

region. The NOAA tidal recording station used to calibrate the model is 

shown as a purple dot.............................................................................................94

 5.20. Comparison of simulated versus measured water levels for NOAA Station 

8570280, 4 to 10 October 1991. .............................................................................95

 5.21. Current speed contours and direction vectors for maximum flooding tide at 

Ocean City Inlet, Md., 5 October 1991. Weaver Shoal, Isle of Wight Shoal, 

and Shoal A are framed as black rectangles for reference.....................................96

 5.22. Current speed contours and direction vectors for maximum ebbing tide at 

Ocean City Inlet, Md., 5 October 1991. Weaver Shoal, Isle of Wight Shoal, 

and Shoal A are framed as black rectangles for reference.....................................97
MMS Study 2010-010 

viii 

LIST OF FIGURES 

(Continued) 

Figure Page 

 5.23. Wave and current vectors used in STWAVE. Subscript a denotes values in 

the absolute frame of reference, and subscript r denotes values in the 

relative frame of reference (with currents). .............................................................99

 5.24. STWAVE bathymetry and model grid domain. The location of WIS Station 

161 is shown as a circle on the eastern boundary..................................................99

 5.25. STWAVE input spectrum developed using WIS 20-year hindcast data with 

the Goda (1985) method of computing frequency and direction spectrum. 

Plots show a) frequency distribution of energy at peak direction, b) 

directional distribution of energy at peak frequency, and c) surface plot of 

energy spectrum (Hmo = 0.9 m, θmean = 130°)........................................................101

 5.26. Wave height values from USACE nearshore gage MD002 during the 1997 

storm. STWAVE results using WIS Station 161 input and wave 

measurements for the nearshore gage are plotted for comparison. The 

difference between simulated wave heights and measurements documents 

maximum difference during the peak of the storm................................................102

 5.27. Wave model bathymetry for the study area. The 12-m contour is outlined 

on each shoal as a reference................................................................................103

 5.28. Wave model results in Hour 40 of the storms with waves incident from a) 

the northeast and b) the east. Note that the color scale range is different for 

the two wave conditions........................................................................................104

 5.29. CMS-M2D model domain is marked by the brown rectangle. The navy 

rectangle illustrates the limits of the STWAVE model grid for comparison. ..........106

 5.30. CMS-M2D model grid showing the variable cell spacing......................................107

 5.31. CMS-M2D model results for existing conditions showing a) bathymetry at 

the start of the model run, b) bottom change calculated for the northeasterly 

storm condition, and c) bottom change for the easterly storm condition. For 

reference, all plots show the 12-m depth contour for Weaver, Isle of Wight, 

and Shoal A. .........................................................................................................110

 5.33. CMS-M2D model results for numerically excavated sand from each of the 

shoals for the Crest Polygon scenario, showing a) bathymetry at the start of 

model run, b) the bottom change calculated for the northeasterly storm 

condition, and c) bottom change from the easterly storm condition. For 

reference, all plots show the 12-m depth contour for Weaver, Isle of Wight, 

and Shoal A. The extents of the “dredging” areas are outlined in black. .............112
MMS Study 2010-010

ix 

LIST OF FIGURES 

(Continued) 

Figure Page 

 5.34. CMS-M2D model results for numerically excavated sand from the leading 

edge of Weaver Shoal and the trailing edge of Isle of Wight Shoal, showing 

a) bathymetry at the start of model run, b) bottom change calculated for the 

northeast storm condition, and c) bottom change from the easterly storm 

condition. For reference, all plots show the 12-m depth contour for Weaver, 

Isle of Wight, and Shoal A. The extents of the “dredging” areas are outlined 

in black. ..........................................................................................................114

 5.35. CMS-M2D model results for dredging a striped pattern from each shoal 

showing a) bathymetry at the start of model run, b) the bottom change 

calculated for the northeast storm condition, and c) bottom change from the 

easterly storm condition. For reference, all plots show the 12-m depth 

contour for Weaver, Isle of Wight, and Shoal A. The extents of the dredging 

areas are also outlined..........................................................................................116
MMS Study 2010-010 

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MMS Study 2010-010 

xi 

LIST OF TABLES 

Table Page 

 1.1. Geometric characteristics of continental shelf sand ridges offshore Maryland 

and Delaware (Swift and Field, 1981).......................................................................4

 3.1. Potential dredging scenario characteristics. ...........................................................34

 4.1. Average abundance of infaunal species accounting for at least 50% of 

within-group similarity in station (sample) Groups A through G. Numbers in 

bold represent average similarity for each group overall. .......................................42

 4.2. Mean number of infaunal taxa within station groups resolved by cluster 

analysis...................................................................................................................42

 4.4. Eggs and larvae of pelagic fish taxa collected in the vicinity of Beach Haven 

Ridge sand shoal offshore New Jersey during 1972 to 1975 and 1992 to 

1995 (From: Able and Hagan, 1995; Able et al., 2006). .........................................48

 4.5. Adult and juvenile demersal fishes collected around sand shoals offshore 

New Jersey, Delaware, and Maryland (Sources: Able and Hagan, 1995; 

Martino and Able, 2003; Able et al., 2006; Slacum et al., 2006; Vasslides 

and Able, 2008).......................................................................................................48

 4.6. Adult and juvenile pelagic fishes collected around sand shoals offshore New 

Jersey, Delaware, and Maryland (From: Able and Hagan, 1995; Martino and 

Able, 2003; Able et al., 2006; Slacum et al., 2006; Vasslides and Able, 

2008).......................................................................................................................50

 4.7. Managed fish and invertebrate species that can utilize offshore sand shoals 

in the Mid-Atlantic Bight. Management agencies include: Mid-Atlantic 

Fishery Management Council (MAFMC); Atlantic States Marine Fishery 

Commission (ASMFC); several State fishery management agencies; 

National Marine Fisheries Service (NMFS), and New England Fishery 

Management Council (NEFMC). The Federal MAFMC and NMFS have 

primary fishery authority of the shoals in the present study. FMP Amd: 

Fishery Management Plan Amendment. HMS: Highly Migratory Species 

rules, NMFS............................................................................................................61

 4.8. Managed invertebrate species that can utilize offshore sand shoals in the 

Mid-Atlantic Bight. Abbreviations provided in Table 4.7. ......................................61

 4.9. Structural habitat types occupying volumes of 1 m3. ..............................................66

 5.1. Potential dredging scenario characteristics. ...........................................................80

 5.2. Reference datums for Ocean City, Md., NOAA Station 8570280. ..........................87

 5.3. Dimensions for the wave grid................................................................................100
MMS Study 2010-010 

xii 

LIST OF TABLES 

(Continued) 

Table Page 

 

 5.4. Selected dredging scenarios.................................................................................108

 5.5. Values for CMS-M2D model variables..................................................................108

 5.6. Summary of Numerical Modeling Results.............................................................118
MMS Study 2010-010 

xiii 

LIST OF ACRONYMS 

2-D two-dimensional 

2G second generation 

3-D three-dimensional 

3G third generation 

ADCIRC Advanced Circulation Model for Oceanic Coastal and Estuarine Waters 

ANOVA analysis of variance 

ASMFC Atlantic States Marine Fishery Commission 

CFR Code of Federal Regulations 

CSA CSA International, Inc. 

CSH cross-shelf habitat 

DGPS differential global positioning system 

EFH essential fish habitat 

ESA Endangered Species Act 

FMP Fishery Management Plan 

GPS global positioning system 

HAPC Habitat Areas of Particular Concern 

HMS Highly Migratory Species 

MAFMC Mid-Atlantic Fishery Management Council 

Mcy million cubic yards 

MEC munitions and explosives of concern 

MGS Maryland Geological Survey 

MHW mean high water 

MLW mean low water 

MMS Minerals Management Service 

MSL mean sea level 

NAVD 88 North American Vertical Datum of 1988 

NDBC National Data Buoy Center 

NEFMC New England Fishery Management Council 

NEPA National Environmental Policy Act 

NGVD National Geodetic Vertical Datum 

NMFS National Marine Fisheries Service 

NOAA National Oceanic and Atmospheric Administration 

NOS National Ocean Service 

OCS Outer Continental Shelf 

SAV submerged aquatic vegetation 

SIMPER similarity percentage breakdown 

STWAVE Steady-state Spectral WAVE Model 

TED turtle-excluding device 

UXO unexploded ordnance 

USACE U.S. Army Corps of Engineers 

VIMS Virginia Institute of Marine Science 

WIS Wave Information Study 
MMS Study 2010-010 

xiv 
MMS Study 2010-010 

1 

1.0 INTRODUCTION 

The Federal Outer Continental Shelf (OCS) contains large sand deposits that are expected to 

serve as long-term sources of borrow material for beach nourishment and coastal restoration 

projects. Potential for exploitation of these resources has grown rapidly in the last several years 

with identification of suitable sand resource areas in some OCS regions. Demand for high 

quality sand suitable for beach nourishment, coastal protection, and other public and private 

projects is anticipated to increase during coming years. 

Considering future beach nourishment needs, renourishment maintenance cycles, and 

anticipated storms, coastal jurisdictions recently have become more interested in sand 

resources seaward of State waters for several reasons. There is increasing awareness that 

sand is a valuable resource and should be carefully managed as such. Onshore sources of 

suitable sand that were once abundant are becoming scarce due to deposit depletion, 

competing uses, and urban development. For ambitious nourishment projects, transporting 

sand from nearshore areas often is far more economical than trucking sand from upland 

sources. Like onshore sources, nearshore sand resources often are limited, diminishing in 

supply, and/or polluted, necessitating the need for alternative deposits that exist farther 

offshore. Using offshore deposits provides the important benefit of adding sand to the 

beach/nearshore system, rather than simply moving sand from one part of the system 

(nearshore) to another (beach). Furthermore, sand resources in Federal waters may be 

environmentally preferable due to concerns that extraction of large quantities of sand and gravel 

from nearshore sites can change the bathymetry of an area and result in modifications to 

existing physical oceanographic conditions. In relatively shallow nearshore waters, alterations 

to local current and wave regimes can have drastic consequences in terms of erosion and 

accretion. From a biological standpoint, excavation of sand resource areas farther from the 

shoreline may prove to have less adverse impacts on essential fish habitat (EFH) than sites 

closer to shore (Jordan, 1999). 

The Minerals Management Service (MMS) is responsible for managing exploration and 

development of mineral resources on submerged Federal OCS lands. Among MMS missions is 

the need to develop approaches for managing the nation’s OCS mineral resources in an 

environmentally sound and safe manner. Anticipating that requests for sand will increase 

significantly due to beach nourishment and storm protection needs, the MMS Sand and Gravel 

Program is ensuring that environmental management processes will be expedited when OCS 

sand resources are most needed. MMS has authority to convey rights to OCS sand, gravel, or 

shell resources for shore protection, beach or wetland restoration projects, or construction 

projects funded in whole or part or authorized by the Federal Government. To further enhance 

and meet its missions, the MMS Sand and Gravel Program funded the project titled “Analysis of 

Potential Biological and Physical Impacts of Dredging on Offshore Ridge and Shoal Features.” 

This document is the Technical Report for the project. 

1.1 OFFSHORE RIDGES AND SHOALS 

Increased demand for beach quality sand from continental shelves fronting the east and Gulf 

coasts of the United States has resulted in numerous geological investigations documenting the 

location of potential sand resource areas, sedimentologic characteristics of deposits, and the 

quantity of sand available in State and Federal waters (e.g., Conkwright et al., 2000; U.S. Army 

Corps of Engineers [USACE], 2008). Most studies have focused on continental shelf sand 
MMS Study 2010-010 

2 

ridges because ridge/shoal features have been identified as a primary source of quality beach 

sand. Shelf ridges are constructive features developed and maintained by modern wave and 

current processes (Huthnance, 1982; Hulscher et al., 1993) in areas of sufficient sand supply in 

a transgressive setting (Snedden and Dalrymple, 1999). Along the mid-Atlantic inner 

continental shelf, Field and Duane (1976), Field (1980), Swift and Field (1981), McBride and 

Moslow (1991), Snedden et al. (1994), Conkwright et al. (2000), USACE (2008), and many 

others document the occurrence and formation of sand ridges and swales similar to those 

shown in Figure 1.1. Extensive ridge and swale deposits in the northeastern Gulf of Mexico 

(east of Mobile Pass on the Alabama and northwest Florida continental shelf; Figure 1.2) have 

been described by Parker et al. (1992), McBride and Byrnes (1995), Parker et al. (1997), 

McBride et al. (1999), and Byrnes et al. (2004). In all shelf ridge settings, the long axis of ridges 

and swales are oriented in the direction of predominant storm wave approach (Hayes and Nairn, 

2004). Storm waves generally approach from the southeast in the northeastern Gulf of Mexico 

and from the northeast in the Mid-Atlantic Bight, indicating a link between storm wave and 

current processes and shoal formation/maintenance (Snedden and Dalrymple, 1999). 

Figure 1.1. Illustration of ridge and swale topography on the mid-Atlantic continental shelf, 

Maryland, and Delaware. 
MMS Study 2010-010 

3 

Figure 1.2. Illustration of ridge and swale topography on the west Florida continental shelf, 

seaward of Pensacola Pass. 

In the early 1970’s, offshore sand resources became an important component of USACE 

projects that focused on beach nourishment for coastal erosion control. Numerous sand 

resource studies were completed by USACE research scientists and other researchers during 

the 1970's and 1980’s to better understand shelf sediment transport processes and patterns on 

the Atlantic inner continental shelf (e.g., Swift et al., 1972). Duane et al. (1972) studied 

approximately 200 shoals at least 910 m long and 3 m in relief to document the characteristics 

of shelf linear sand ridges between Long Island (New York) and Florida. Swift and Field (1981) 

documented geomorphic characteristics of shoreface-attached, nearshore-detached, and 

offshore-detached sand ridges for the best developed ridge and swale topography in the 

Mid-Atlantic Bight. Shoreface ridges extend from the shoreface in water depths as shallow as 

3 m at an oblique angle. Ridge side slopes average about 1.5o, and they are generally 

symmetrical (Swift and Field, 1981). 

Nearshore-detached sand ridges are generally more massive than shoreface-attached and 

have smooth, single-crested southern ends. The average seaward slope of the ridges is about 

two times as steep as the average landward slope; however, both slopes are less than those 

associated with shoreface ridges (Swift and Field, 1981). Furthermore, the highest point on 

ridges occurs toward the southern end of the shoal before decreasing abruptly to the ambient 
MMS Study 2010-010 

4 

shelf surface. Offshore-detached sand ridges are similar to nearshore ridges except they are 

typically less elongate and have greater cross-sectional areas and seaward slopes many times 

steeper than landward flanks (Swift and Field, 1981). USACE (2008) provided a summary of 

shoal characteristics derived from Swift and Field (1981) documenting geomorphic differences 

among the three categories of continental shelf sand ridges (Table 1.1). 

Table 1.1. Geometric characteristics of continental shelf sand ridges offshore Maryland and 

Delaware (Swift and Field, 1981). 

Geomorphic Characteristics of Shoal Type 

Continental Shelf Sand Ridges Shoreface-Attached Nearshore-Detached Offshore-Detached 

Shape Linear Linear Comma 

Ambient water depth (m) >3 <12 >12 

Mean slope 1.5o 1.0o 0.5o 

Steepest slope 2.5o 2.0o 7.0o 

Steepest flank Landward Seaward Seaward 

Mean asymmetry 

(landward : seaward slope) 1:1 1:2 1:5 

Mean aspect ratio 

(length : width) 9:1 6:1 3:1 

Maximum cross sectional area 

(x 103 m2

) 87 187 4,481 

Shelf sand ridges are common along the Atlantic and Gulf coasts of the United States. 

However, considerable variability in geomorphic and sedimentologic characteristics exists as a 

function of sediment source and dominant wave and current processes. Snedden and 

Dalrymple (1999) presented a comprehensive analysis of shelf sand ridge formation and 

evolution and proposed a unified conceptual model of ridge origin and evolution that 

encompasses ridge variability. The conceptual model consisted of three components: 

1) formation of an initial irregularity on the shelf surface upon which modern ridges develop; 

2) the interaction of storm and shelf-current processes in the presence of the initial seafloor 

irregularity to form and maintain the modern sand ridge (described by Huthnance [1982] and 

Hulscher et al. [1993]); and 3) subsequent ridge evolution in response to modern wave and 

current processes. 

Hayes and Nairn (2004) reviewed the natural maintenance of sand ridges on continental 

shelves relative to potential offshore sand mining on these ridges. They recognized the value of 

the Huthnance model for describing the evolution of tidal sand ridges; however, it was 

emphasized that the following primary constraints had to be met for the model to predict 

properly: 1) a sufficient quantity of sand; 2) currents capable of moving the sand; and 3) a 

pre-existing seafloor irregularity. For storm-dominated shelves, Trowbridge (1995) proposed 

that southerly currents generated by northeast storm waves would produce the same response 

on sand ridges as asymmetrical tidal currents imposed by Huthnance (1982). Although 

limitations exist with all sand ridge evolution theories, Snedden and Dalrymple (1999) used 

various geological data sets to develop an evolutionary progression of sand ridges on 

continental shelves (Figure 1.3). The process by which this progression occurs is described by 

Snedden et al. (1999). 
MMS Study 2010-010 

5 

Figure 1.3. Schematic diagram of ridge classes as presented in Snedden and Dalrymple 

(1999). The precursor in the case of the Class I and II ridges is a pre-existing 

bathymetric feature, sometimes associated with a shoreline or inlet, which provides 

the focal point for the ridge growth and migration via the Huthnance process. 

Subsequently, this precursor may be removed or reduced in size through current 

erosion and ridge migration. Accretion on the landward side of the juvenile ridge 

(Class I) is largely induced by fair-weather wave transport from the ridge crest and 

is not expected to occur in ridges developed in deeper water, as with Classes II and 

III. New ridge sand is primarily deposited in shelf waters by combined flows 

associated with storms. 

Recognizing that shelf sand ridges are modern constructive features that form and migrate in 

response to dominant coastal processes, scientists and engineers have identified these 

deposits as primary resource targets for beach nourishment and coastal restoration. Numerous 

site-specific environmental studies have been completed for Federal and State agencies 

responsible for managing sand resources on the continental shelf (e.g., Drucker et al., 2004) to 

evaluate the potential effects of sand mining from offshore shoals on local and regional sand 

transport patterns. In all studies where changes in wave and current processes were evaluated 

relative to sand mining on offshore shoals, there have been no significant changes in regional 

sand transport patterns (e.g., Byrnes et al., 2004; Maa et al., 2004). 

Hayes and Nairn (2004) indicate that the direct influence of wave action has received little 

attention with regards to the maintenance and migration of shelf ridge and swale features. They 

applied a Boussinesq wave model using a wave representative of northeast storm conditions to 

simulate irregular multidirectional waves that included partial reflection and current interaction. 

The simulation illustrated refraction over Fenwick Shoal that created wave convergence on the 

shoal crest. It was suggested that wave convergence on the shoal crest may be a primary 
MMS Study 2010-010 

6 

factor for maintaining shoals aligned with the dominant wave direction (Hayes and Nairn, 2004). 

Furthermore, because converging waves exist on the shoal crest, convergence of sand 

transport likely occurs on the crest as well. 

Although consensus does not appear to exist regarding dominant processes responsible for 

ridge evolution and maintenance, the formation and maintenance processes described by 

Huthnance (1982), Trowbridge (1995), and Hayes and Nairn (2004) can explain shoal 

morphodynamics and sediment transport mechanics for most, if not all, shelf sand ridges. In 

every case, these features are depositional, and many migrate in response to dominant coastal 

processes. The shallower the ridge, the more likely wave processes will control 

morphodynamics. Where shelf currents overwhelm wave-induced currents responsible for sand 

transport and ridge maintenance, shoal evolution may be best described by Huthnance (1982). 

When wave-driven flow is dominant, convergence at ridge crests may be best described by 

Hayes and Nairn (2004). Either way, as long as an initial seafloor irregularity is present on the 

shelf upon which waves and currents can mold and create shelf ridges, these features will 

continue to grow and migrate providing regional shelf transport processes are maintained. 

1.2 STUDY OBJECTIVE AND QUESTIONS 

The MMS specified the study objective and posed questions to be addressed during the project. 

The objective of the study was to examine and evaluate potential biological and physical effects 

of offshore dredging within ridge and swale features on the Federal OCS and to suggest 

engineering options and mitigation measures that can be implemented to avoid potential 

deleterious impacts, while allowing for the selective removal of needed sand volumes for nearby 

beach projects. To address this objective, the MMS requested that a program be developed to 

address biological and physical issues associated with the long-term use of offshore sand 

ridges as a source of sand borrow material for beach and coastal restoration efforts and suggest 

engineering options/dredging techniques to allow for the selective removal of sand for beach 

restoration and nourishment projects. Specifically, the MMS posed the following four questions 

relative to continued use of offshore submerged shoals and the ridge and swale features that 

occur on the OCS. These questions were incorporated into the technical approach discussed in 

Section 1.3.1. These questions originated and were discussed as information gaps during an 

MMS-funded study (Research Planning, Inc. et al., 2001) conducted prior to the present study. 

 What is the use and role of sand ridges and shoals as potential EFH by migrating or resident 

fish? (Figure 1.4, Boxes 3 and 8; see Section 4.0). 

 Is there a preferred manner to remove sand from a shoal/ridge feature to maximize its use 

and maintain the integrity of the feature? (Figure 1.4, Boxes 5, 6, and 8; see Section 6.1). 

 Are there benthic biological differences that run longitudinally along the ridge and shoal 

features such that dredging operations should be tailored to avoid certain areas? 

(Figure 1.4, Boxes 4 and 8; see Section 6.2). 

 Are there procedures to dredge shoal and ridge features that will minimize ecological 

impacts and/or speed recovery, such as completely dredging one specific shoal or ridge and 

leaving adjacent features untouched versus dredging a small amount of sand from each 

shoal or ridge feature, or dredging in strips, leaving undisturbed areas that act as local 

sources of recruitment and allow recruitment from older life stages? (Figure 1.4, Boxes 2, 5, 

and 8; see Section 6.3). 
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Figure 1.4. Flowchart of technical approach. 
MMS Study 2010-010 

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1.3 STUDY DESIGN 

1.3.1 Technical Approach 

To accomplish the study objective, a technical approach consisting of nine steps was 

developed (Figure 1.4). The first step of the technical approach was to collect pertinent 

published and unpublished study results on ridges, shoals, and swales (Figure 1.4, Box 1). 

Information was collected from author libraries, other private and public libraries, and internet 

websites. 

The second step was to review procedures to dredge ridge, shoal, and swale features 

(Figure 1.4, Box 2). The review included cutterhead dredges, hopper dredges, and other 

offshore dredging equipment and techniques as described in Section 2.0. 

The third and fourth steps concerned biological tasks. The third step was to review pertinent 

studies to ascertain the role of ridges, shoals, and swales as EFH (Figure 1.4, Box 3). To 

adequately address the third step, a cross-shelf framework was used (Section 4.6). The fourth 

step was to review pertinent studies to ascertain patterns of benthic biological differences 

across ridges, shoals, and swales (Figure 1.4, Box 4). The results of the third and fourth steps 

are presented in Section 4.0. 

The cross-shelf approach was chosen because EFH is broadly defined as "those waters and 

substrate necessary to fish for spawning, breeding, feeding or growth to maturity," which covers 

the full spectrum of life histories and habitats rather than only ridges, shoals, and swales. The 

EFH definition demands considerations of life histories and estuarine to shelf habitats. 

Considering only ridges, shoals, and swales is too myopic compared to the preferable 

cross-shelf matrix approach. To fully understand the role and use of ridges, shoals, and swales 

by resident and migratory fishes, a broader scale approach is needed. The cross-shelf matrix 

enables identification of the wide variety of habitats where various life stages occur. The 

cross-shelf approach also helps identify which species are true residents and which species are 

actually migratory. Important migrations are not only broad-scale coastal movements but also 

developmental, ranging from inshore nursery to offshore adult habitats. Some species and life 

stages may be very general in their habitat requirements, whereas others may prove to be 

highly dependent on ridges and shoals. For example, if juvenile fishes of a particular species 

occur only on shoals and not in estuaries, inlets, and other inner and outer shelf habitats, then a 

statement can be made based on the cross-shelf matrix that shoals are EFH for that particular 

species and life stage. Such findings will not be readily apparent if ridges and shoals are 

considered in isolation from the surrounding habitats. The cross-shelf approach provides a 

proactive assessment of EFH, uncovering habitat connectivity of individual species life history 

stages within the region. The cross-shelf matrix provides a tool that can be used along the East 

and Gulf Coasts to properly determine if shoals and swales are truly EFH and helps to answer 

the question "What is the use and role of sand ridges and shoals as potential EFH by migrating 

or resident fish?" 
MMS Study 2010-010 

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The fifth step was to develop dredging scenarios (Figure 1.4, Box 5). Existing knowledge of 

borrow site geometries was considered relative to environmental and economic considerations. 

Equipment and techniques available under existing and emerging technologies also were 

evaluated. Dredging scenarios were then designed to include the natural, long-term evolution of 

the shoal. Some potential dredging scenarios specified by the MMS and considered at the 

beginning of the project were as follows: 

 Dredging completely one specific ridge or shoal and leaving adjacent features untouched; 

 Dredging a small amount of sand from each shoal or ridge feature; and 

 Dredging in strips, leaving undisturbed areas that act as local sources of recruitment and 

allow recruitment from older life stages. 

These and other dredging scenarios were considered during the project as discussed in 

Section 5.1.2. 

The sixth step was to conduct numerical modeling to simulate physical impacts of different 

dredging strategies (Figure 1.4, Box 6). The purpose of the modeling approach was to provide 

baseline information on potential physical impacts, and to evaluate the physical impact 

producing factors (i.e., sediment removal, suspension/dispersion [turbidity], deposition [changes 

in sediment thickness and grain size], and other potential physical disturbances from dredging 

and positioning equipment) such that modeling results could be used to provide statements 

concerning potential biological impacts of dredging offshore ridge and shoal features. Emphasis 

was placed on estimating the physical impact producing factors associated with selected 

dredging scenarios that could be applicable to evaluating near-field and far-field, and short-term 

and long-term biological impacts. 

The seventh step was to review modeling results to evaluate potential impacts on biological 

communities (Figure 1.4, Box 7). Based on the results of the sixth step, modeling results 

concerning the physical impact producing factors (i.e., sediment removal, suspension/dispersion 

[turbidity], deposition [changes in sediment thickness and grain size], and other potential 

physical disturbances from dredging and positioning equipment) were used to base statements 

concerning potential biological impacts of dredging offshore ridge and shoal features. Biological 

statements are presented in Sections 6.2 and 6.3. 

The eighth step was to discuss the advantages and disadvantages of each dredging approach 

(Figure 1.4, Box 8). During discussions, results relative to the relationship between dredging 

technologies and potential physical and biological impacts were assessed. Comparisons were 

made of the selected dredging alternatives, and dredging options and mitigation measures were 

recommended as presented in Section 7.0. 

The ninth step was to produce the Technical Report (Figure 1.4, Box 9). This document is the 

Technical Report, and its organization is described in Section 1.4. 

1.3.2 Study Area 

The study area encompasses three primary sand shoals in Federal waters offshore the ocean 

shoreline of Maryland. Maryland’s coast is comprised of Fenwick and Assateague Islands. The 

northern end of Fenwick Island is connected to mainland Delaware, and the southern end of 

Assateague Island extends into Virginia. Ocean City is situated at the southern tip of Fenwick 

Island, just north of Ocean City Inlet (Figure 1.5). 
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Figure 1.5. U.S. mid-Atlantic coast, showing the location of Ocean City, Md., and surrounding 

states. 

The continental shelf in this area extends from the Ocean City shoreline seaward about 120 km. 

The seafloor of the shelf slopes gently seaward to its eastern edge, where water depths are 

approximately 200 m. Shelf sediments are derived from deposition and erosion of sediments 

along the continental margin. They include gravel, sand, silt, and clay, as well as seashells and 

plant remains, and are mainly unconsolidated. These sediments have been reworked by waves 

and currents accompanied by the rise and fall of sea level. Beaches within the study area 

currently are experiencing a rise in sea level of about 3 mm per year (National Oceanic and 
MMS Study 2010-010 

11 

Atmospheric Administration [NOAA], 2001). Shelf geomorphology is mostly flat but contains a 

large number of nearshore and offshore sand shoals (Figure 1.6). These shoals have been 

studied by many academic scientists as well as the MMS, USACE, and Maryland Geological 

Survey (MGS). Studies have evaluated the shoals as potential sources of sand for beach 

nourishment on Fenwick and Assateague Islands. MGS studied 22 large shoals off the 

Maryland coast, and Swift and Field (1981) identified 35 large shoals in the study area. 

Figure 1.6. Bathymetric map of the study area, documenting three offshore shoals evaluated 

for potential sand mining for Ocean City, Md., beach nourishment. 

Shoreface shoals located offshore Fenwick and Assateague Islands primarily have long axes 

with a southwest/northeast orientation. Shoal morphology data compiled by MGS show that 

shoal crests and base water depths gradually increase offshore (USACE, 2008). Shoals range 

from 1.8 to 27.2 km2

 in area, 3.2 to 11.3 km in length, and 1 to 4 km in maximum width. 
MMS Study 2010-010 

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Seafloor relief ranges from 7.6 to 15.2 m, and side slopes range from 0.2° to 7.0°. Shoals with 

larger volumes typically have greater area and relief. The surface of shoals, as well as the 

surrounding seafloor, often contains smaller scale geomorphic features such as flat plane beds, 

ripples, and sand waves. 

McBride and Moslow (1991), Snedden et al. (1994), and McBride et al. (1999) indicate that 

nearshore and offshore shoals are most likely formed concomitant with the development and 

migration of inlets and ebb-tidal shoals. Over the last several thousand years, sea level has 

risen and caused ebb shoals to detach from the shore and change independently from the 

retreating shoreline. As water deepened, shoals were less affected by fair-weather waves and 

continued to migrate and gradually increase in cross-sectional area. This increase in area was 

accompanied by decreased length to width ratio and grain-size increases on the shoal crest. 

Storm waves originating from the northeast caused the southwest/northeast alignment of a 

majority of the shoals. MGS studies in two borrow areas found shoals to migrate south at a rate 

of 4.5 to 9 m per year, whereas Swift and Field (1981) found that the larger shoals typically 

migrate to the southeast at rates of 2 to 120 m per year. 

Shoals and intershoal regions are predominantly composed of fine to coarse well-sorted sand 

that is highly variable in thickness and areal extent. As shoals migrate and sand is reworked, 

coarser sediment becomes concentrated in areas of greatest wave and current energies, 

typically located along the crests of shoals. The crests contain very little shell material. Shoal 

flanks are composed of sand and some shell and biogenic material. Intershoal sands contain 

the most biogenic material, but it is never abundant. Wave and current energies prevent mud 

from being deposited in the area. Existing mud and fine sand from underlying deposits are 

often locally exposed on the seafloor. Sand deposits in these areas are usually only a few 

meters thick and have an overall grain size smaller than that of shoals and mainland beaches. 

The study area was selected based on near-term need for sand resources, availability of 

geological data and previous studies describing shelf sand ridges in the area, and the 

availability of associated biological resource data and studies. The shoal field offshore the 

northern Maryland coast was an ideal selection because all of the above criteria were met. The 

Atlantic Coast of Maryland Shoreline Protection Project reevaluation study (USACE, 2008) 

identified nine offshore sand shoals as potential sources for beach replenishment material. 

Geological investigations of these shoals were completed by Conkwright and Williams (1996) 

and Conkwright et al. (2000). Based on analysis of geological data, biological considerations, 

geographic location, and concerns regarding unexploded ordnance, USACE (2008) selected 

four shoals for detailed evaluation as potential sources of sand to meet beach nourishment 

needs at Ocean City, Md. From these selected shoals, the CSA International, Inc. (CSA) study 

team chose to evaluate the potential physical and biological impacts of sand mining on Weaver 

Shoal, Isle of Wight Shoal, and Shoal A (Figure 1.6) using hydrodynamic, wave, and sediment 

transport modeling tools, and existing biological data (e.g., Slacum et al., 2006) to address the 

questions described in Section 1.2. 
MMS Study 2010-010 

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These three potential borrow areas were evaluated by obtaining sand samples collected from 

vibracores and grab samples. Patterns of grain size distribution determined from these 

analyses are displayed in Figures 1.7, 1.8, and 1.9. Sand borrow area maps were created by 

USACE and superimposed on the 2002 bathymetry surface. Ideally, sand source grain size 

should be similar to that of beach sand currently present at the site of beach nourishment. Prior 

to regular beach nourishment that began in 1988, Ocean City beach sand had a mean grain 

size of 0.6 mm (USACE, 1989). After several beach fills using offshore sand, mean grain size in 

1993 was 0.43 mm (USACE, 2008). 

Weaver Shoal is the most northern shoal to evaluate. The mapped area is approximately 4 km 

long and 2 km wide. Vibracore sample analysis identified two parts of the shoal that contain 

acceptable sand for beach nourishment: the crest and leading edge and the northern half of the 

trailing edge. Isle of Wight Shoal is located 4 km to the southwest of Weaver Shoal. It is 6.5 km 

long and 2 km wide. Sand samples from this feature revealed the southeastern part of the 

trailing edge and the crest of the shoal to contain sand acceptable for beach nourishment. 

Shoal A is located 6.5 km to the southeast of Isle of Wight Shoal. The mapped area is 5 km 

long and 1.5 km wide. Vibracore samples extracted from the shoal identified only the southern 

two-thirds of the trailing edge of the shoal to be compatible with beach sand on Fenwick Island. 

1.4 DOCUMENT ORGANIZATION 

This document is organized into eight major sections: 

 Section 1.0 – Introduction; 

 Section 2.0 – Offshore Dredging Procedures at Ridges and Shoals – Offshore Dredging 

Equipment and Techniques; 

 Section 3.0 – Physical Impact Producing Factors Associated with Sand Mining on Shoals 

Offshore Maryland; 

 Section 4.0 – Evaluation of Biological Resources Associated with Shoals Offshore Maryland; 

 Section 5.0 – Selection of Alternative Scenarios and Simulation of Physical Processes; 

 Section 6.0 – Questions and Alternatives for Optimizing Physical-Biological Impacts of Shoal 

Dredging; 

 Section 7.0 – Recommendations for Engineering Options and Mitigation Measures; and 

 Section 8.0 – Literature Cited. 
MMS Study 2010-010 

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Figure 1.7. Weaver Shoal sand resource acceptability classification by USACE (2008). 
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Figure 1.8. Isle of Wight Shoal sand resource acceptability classification by USACE (2008). 
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Figure 1.9. Shoal A sand resource acceptability classification by USACE (2008). 
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2.0 OFFSHORE DREDGING PROCEDURES AT RIDGES AND SHOALS – 

OFFSHORE DREDGING EQUIPMENT AND TECHNIQUES 

(Ancil S. Taylor – C.F. Bean, L.L.C.) 

This section describes various types of dredging equipment, methods, procedures, and 

contractor expectations common to offshore borrow areas used in the restoration of coastal 

features such as beaches, shorelines, and barrier islands. There are two types of dredges 

commonly used in the removal of sediment from ridges, shoals, and other types of offshore 

borrow areas. Hydraulic cutterhead dredges and trailing suction hopper dredges are most 

commonly used. In some rare circumstances, dustpan dredges have been used, and in even 

more rare occasions, the Punaise, or as it has been referred to, the “thumbtack,” has also been 

used. This section addresses these types of dredges as well. 

2.1 CUTTERHEAD DREDGES 

These dredges incorporate the use of a cutterhead near the suction mouth to dislodge the 

excavated material from the seafloor and assist in the 

slurrification of the sediment for removal by the suction 

mouth of the dredge. The dredged material is transported 

up the suction mouth and propelled away from the dredge 

via a centrifugal dredge pump. The material is transported 

through a pipeline to the destination, where it is either 

shaped into the desired fill dimensions or stockpiled for 

further rehandling. The following is a description of some of 

the more significant pieces of equipment and dredging 

related issues attached to the cutterhead dredge operation. 

2.1.1 Dredging Equipment 

Cutterheads are designed for different purposes and effectiveness, but in general, most have 

five to six blades. The cutterhead depicted here has six blades. The shape of the blades is 

optimized to maximize the “feeding” of material into the 

suction mouth. The cutterhead is designed to rotate, 

causing each blade to come in contact with the sediment as 

it rotates around the axis. Each blade is designed to 

incorporate certain types of cutting edges. Cutting edges 

are those leading edges of the blade that come into direct 

contact with the sediment as the cutterhead rotates on its 

shaft. This picture depicts a new cutter tooth next to a worn 

cutter tooth. Cutter edges can be smooth or serrated. The 

blades may also be outfitted with adapters that allow 

interchangeability in the types of teeth that can be attached 

to the blade and adapter. Teeth can be wide to narrow 

chisel-shaped, or they can be pointed like a pick point. This 

interchangeability allows the dredge to optimize the 

production and cost efficiency of the dredge in removal of 

sediments. Oftentimes, there is substantially more material 

that actually comes in contact with the blades than is actually 

removed by the suction mouth. This is referred to as 

“spillage” and will be addressed later in this section. 
MMS Study 2010-010 

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Anchors are used to moor the cutterhead dredge and other dredging related equipment to the 

seafloor for dredging operations. Swing anchors will be used on a cutterhead dredge to swing 

the dredge back and forth to allow the cutterhead to become engaged with the sediments. 

Christmas tree anchors may also be used on a cutterhead to stabilize a pivot point near the 

stern of the dredge around which the dredge can maintain a steady arc as it cuts through the 

sediments. Pipeline anchors can be used along the length of a floating slurry pipeline, steel or 

rubber, to moor the pipeline in a location near the dredge while the slurry is transported through 

it. Ancillary equipment mooring anchors will also be used to temporarily moor other equipment 

near and around the dredge for easy access by the dredge crew should repairs or typical 

dredge operations require the equipment. 

Anchor placement and techniques commonly involve moving or dragging anchors along the 

seafloor by anchor handling tug boats with stern winches, anchor handling derricks, and/or 

anchor booms attached to the dredge. Anchors are designed for various types of material. 

Optimum anchor design or efficiency focuses on maximizing holding capacity with the least 

amount of weight. Anchors are designed to penetrate the bottom and bury themselves as soon 

as possible, minimizing dragging along the bottom before it “holds.” Anchors are commonly 

attached at the shank with a chain and then a steel anchor wire. Anchor handling boats 

equipped with a stern winch attach a hook to a pendant wire1

 suspended by a buoy at the 

surface of the water. The other end of the pendant wire is attached to the tripping ring near the 

anchor stock. This permits the anchor to be removed from the seabed by backing the flukes out 

from the bottom. Once removed, the anchor handling boat will either winch the pendant wire 

aboard, thereby completely removing the anchor from the seabed if the water is deep enough or 

drag the anchor to the next location if the water is too shallow. 

Anchor handling derricks are also attached to the anchor in the same way and will transport the 

anchor to the next location, similar to the anchor handling boat. The anchor handling derrick 

affords the anchor shifting operation the additional capability of actually removing the anchor 

from the water and placing the anchor on the deck of the derrick to assist with unfouling the 

anchor lines or changing/repairing anchors or wires. 

Anchor booms are boom extensions that are attached to the hull of the dredge and used to lift 

the anchors from the sea bottom and swing the anchor to the next location. The operating 

principle is simple: at rest, the boom will always move back and away from the cutter, thus 

preventing the anchor hoisting wire from being dredged up. When the wire is tensioned, the 

boom will move above the anchor to break it out. When the anchor is broken out of the soil, the 

wires will automatically pull the boom forward to the new anchor position. After lowering the 

anchor, the boom will fall back into the resting position. Optionally, the anchor boom can be 

delivered with a slewing winch, so that the boom can also be moved backwards with a load. 

Anchor types include Danforth, Bruce, and Delta in more commonplace applications. There are 

many variations on these types of anchors, and some companies further modify the anchors 

with block to “fix” the angle of the flukes to the shank to improve anchor performance. 

Wires rope(s) are a consumable for a dredging project. Steel wires come in many different 

designs, type of lays, number of strands, type of core, etc., depending upon the application. 

Wire ropes can be found in many locations on the dredging project. They will attach the dredge 

 

1 A pendant wire is a short piece of wire rope that is approximately as long as the water is deep in the vicinity of where the anchor 

application is. This allows equipment at the surface to attach to the anchor at a location that will remove the anchor from the 

bottom most efficiently. Oftentimes, a buoy floats at the surface with the pendant wire passing through the buoy, making it easy 

for the surface equipment (i.e., anchor handling boat) to access the wire. 
MMS Study 2010-010 

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ladder swing winches to the swing anchors. Wire ropes also will attach Christmas tree winches 

on the dredge to the Christmas tree anchors. They will attach the floating line anchors to the 

floating pipeline. They will be used to raft or connect pipelines together for transport. They may 

be used to tow barges or other vessels on a project. They attach to the dredge ladder to allow 

the dredge operator to raise and lower the ladder for adjusting the dredge elevation. 

Bottom impacts from wires may occur because wire ropes do not float and are subject to sinking 

to the sea bottom. Wire ropes attached to anchors impact the bottom by dragging along the 

seafloor. These impacts can be minimized to some degree by deploying additional swing wire 

floats, sometimes referred to as surge buoys, which attempt to suspend the swing wire above 

the seafloor. This effort does not eliminate impact with the seafloor but can reduce impact over 

much of the swing wire length. This application is somewhat less effective in the Christmas tree 

application due to the rigid and taut application of the anchor wires. 

Christmas trees moorings are normally deployed only in offshore environments where the use of 

spuds is too dangerous due to wave climate. This type of anchoring device is commonly 

designed to moor the point on the dredge around which the cutter dredge swings. This is most 

often a point on the stern where the dredge slurry pipeline connects to the hull. Christmas trees 

are normally a three-point anchoring configuration with a stern anchor and two quarter anchors 

that stretch forward and angle away from the dredge cut. 

Spuds are used to pivot the cutter dredge around an arc to engage the sediments with the 

cutter. These spuds are of appropriate length to extend into the sea bottom and up to a point 

above the dredge hull to be held in place by spud keepers, a gantry, or other lifting device and 

wire ropes. The spud will penetrate into the seafloor to a depth that is a function of the spud’s 

design, weight, length of time at a given location, the type of material, and resistance to 

penetration in which the spud is placed. Spuds are used in two general types of configurations 

for cutter dredges, the fixed spud application and the spud carriage application. The use of 

spuds in offshore environments is fairly uncommon in the United States, while the use of 

Christmas tree mooring is fairly uncommon in the international market. 

Boats are necessary for effecting operations on a dredging project. Several types of boats are 

commonly found on projects and require various levels of licensing and training, depending 

upon the boat class. 

Work boats are those boats engaged in the day-to-day operations of facilitating the physical 

movement of the dredge and its equipment through the project requirements. These boats may 

assist with anchor handling needs, anchor barge 

movement, pipeline handling needs, vessel transport, 

ferrying fuel and/or water to various pieces of floating plant 

on the project, including the dredge. These boats are 

commonly measured in horsepower and may range from 

200 to 5,000 horsepower depending upon the application. 

Most cutterhead dredge projects will include a minimum of 

two of these type boats and sometimes up to four 

depending upon the type of project. 

Crew boats are primarily used to ferry people, small supplies, and groceries to and from various 

locations on the project to its land-base of operations, the landing. In the offshore environment, 

one seldom sees crew boats smaller than 14 m in length and up to 37 m in length on some 
MMS Study 2010-010 

20 

special needs projects. Generally, crew boats travel at speeds of 18 to 23 knots, loads and sea 

conditions permitting. 

Survey boats are used as a platform from which to measure the elevations and locations of the 

bottom contours. In today’s applications, they incorporate differential global positioning systems 

(DGPS) for determining horizontal location 

and various types of sonar for measuring 

water depths at the measured horizontal 

locations. These boats supply project 

management with critical information about 

dredge performance, project layout, and 

resource planning. They may also provide a 

platform from which water quality sampling 

for turbidity and or dissolved oxygen might be 

measured. In most cases, there is very little 

need for the boats to come in contact with the 

seabed except in a situation where anchoring 

for boat repair or diving operations may be 

necessary. 

Barges are often deployed on projects as platforms for supplies, pipelines, spare cutters, and 

other major large spare parts. Barges are commonly moored inside a harbor protected from 

exposure to the wave climate and transported to the project only when it is necessary to utilize 

that platform offshore. In some cases, these barges are outfitted with spuds for mooring in 

water depths of less than 12 m or so and in calm water. 

2.1.2 Global Positioning System (GPS) 

Satellite positioning has become the standard within the industry that would normally be 

engaged in offshore mining. GPS, with and without differential correction, is the most commonly 

used form of horizontal positioning in dredging operations today. It utilizes satellite positioning 

adjusted by a local differential station. Dredges complement the horizontal positioning with 

various forms of elevation-measuring technology to determine critical elevations around the 

dredge hull. These elevations are used to extrapolate to a point on the cutter to indicate 

“dredge depth”2

 and horizontal cutter locations, X, Y, and Z, of the cutterhead. These three 

coordinates are often reported in state plane coordinates for X and Y and elevation in feet or 

meters for Z. 

GPS positioning technology has grown significantly in the last decade and has become the tool 

of choice for dredging applications. Limitations are predominantly confined to the occasional 

but rare loss of a suitable satellite constellation. Accuracy for GPS systems are expected to be 

submeter. This is more than sufficient for horizontal measurements to accommodate most 

offshore dredging applications. Reporting is relatively easy once the dredge has been outfitted 

with the appropriate equipment to measure position via GPS and elevations via the sensors and 

 

2

 Dredge depth is a term that is yet to be defined by a standard in the industry. There are at least three different depths that could 

be reported: 

1. The maximum depth of the cutter’s impact to the bottom sediments. 

2. The depth of the suction mouth that is actually above the maximum depth of the cutter’s impact 

3. The elevation at which the seafloor remains after dredging. 

The difference between Points 1 and 2 could be as much as 0.6 to 1.5 m. The difference between Points 1 and 3 could be as 

much as 1 to 2.1 m or more.
MMS Study 2010-010 

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software to perform the calculations. Reporting the position on a routine basis is simply a 

matter of programming, and telemetry of the data ashore. 

2.1.3 Dredging Techniques in Sand Ridges and Shoals 

Deep mining (glory hole) has been a method of mining sand in the offshore environment of the 

past. The holes are still evident and noticeable off the coast of Florida from coastal 

restoration/renourishment projects in the 1960’s and 1970’s. Mining sand in this manner would 

yield the maximum productivity and cost efficiency for removal. It simply involved placing the 

suction mouth of the dredge, with or without an agitation device like a cutter, on the seabed and 

continuing to lower the suction depth until the borrow pit yield diminished. Once the sand quit 

flowing to the suction mouth, the dredge would either advance or start in a new location. 

Thin layer removal is often required when there is only a thin layer of suitable material available 

for the project. In the context of this document, thin layer could be considered any bank of sand 

less than 1.8 to 2.4 m thick. There are numerous implications associated with thin layer 

availability and removal. The thin layer could be overlain and underlain by unsuitable material. 

Unsuitable material could be defined as a very fine silty mud or a layer of very rocky sediments, 

neither of which might be considered as suitable for the renourishment project. Due to spillage3

and mixing around the suction mouth and cutterhead, this unsuitable sediment would be 

intermixed in large percentages, with the more suitable sediments, diminishing the suitability of 

the targeted thin layer of material. 

Aggressive, maximum spillage is a method of removal that is common when the sediment 

transportation capability of the dredge is sufficient to permit high percentage concentration by 

volume of sediment in the slurry. A dredge can move through a bank of material with a high 

percent of spillage, 40% to 60%, and maintain a high production and lower cost. For example, if 

the suction mouth or dredging depth is measured 3 to 4 m below the top of the sediment, the 

dredge will remove only 5 to 6 ft of material, allowing 5 to 6 ft of material to fall behind the cutter 

and remain on the bottom, resulting in a 50% spillage factor. This method would permit the 

most efficient removal and dredging cost to the removal effort. Obviously, one of the results of 

this approach is the homogenizing of the original 3 to 4 m of bank and the resulting removal and 

spillage of that homogenized mixture. This approach is available only in borrow areas that are 

of sufficient depth to allow the dredge ladder to continue to swing with a high percent of spillage 

falling behind the cutter, otherwise, ladder dragging will occur, resulting in adverse production 

impacts. 

Slow, minimum spillage is the other extreme of the aggressive, maximum spillage method 

described above. This method could result in a spillage factor as low as 15% to 20% and also 

will result in a much lower productivity with higher cost implications. This method may be 

chosen by a contractor when available borrow material is limited and a more complete 

evacuation of the borrow area may be necessary to achieve the necessary quantities. If a 

dredge has slurry transportation capability limits, the operator could choose to combine these 

two limitations, resulting in less of an impact due to the reduced spillage. It should be up to the 

project planner or contractor’s project engineer to optimize these production limit relationships 

and dynamics. 

 

3

 Spillage is defined in ERDC/TN EEDP-04-37, June 2007, page 16. This document was prepared by the Engineering Research 

Development Center for the USACE in Vicksburg, MS. 
MMS Study 2010-010 

22 

Angle of attack for sea conditions is an important factor in borrow area design. Cutter dredges 

working in an offshore environment prefer to optimize their angle against the wave climate 

characteristics. A cutter dredge may swing 80o to 100o through an arc, depending upon the 

waves. The operator would prefer to keep the seas hitting his hull as close to longitudinal as 

possible through much of the exposed arc. Operators prefer to avoid any part of the swing 

where the dredge is exposed to sitting in the trough of the 

wave. 

Borrow area dimensions and locations are very important for 

the cost and efficiency impacts of the dredging issues related 

to a project. Both of these issues might determine the type of 

dredge that would be used by a contractor. This issue is much 

more involved than could be covered in this document; 

however, optimizing the dimensions and locations would 

include almost all of the parameters and issues presented in 

this document. 

2.1.4 Dredged Material Transportation and Pipelines 

Floating pipelines (flexibility around the mining area) are very 

important for a cutter dredge. In most cases, cutter dredges 

working in the offshore environment will be accompanied by a 

rough water pipeline made of rubber with floatation wrapped 

around it. In some cases, the rubber lines are augmented with 

steel lines to increase length and reduce average cost/unit of 

length of the rough water pipeline. These steel pipes often 

have rough water floats wrapped around them as well. This 

pipeline is connected to the dredge on one end and to another 

type of pipe on the other end, called riser pipes. 

Riser pipelines allow the floating flexible line to be connected 

to a stationary submerged pipeline. These riser pipes are 

submerged at an angle to allow some flexibility near the 

surface while remaining anchored at the seabed by the 

submerged pipeline or other anchoring device. 

Submerged pipelines allow for efficient transportation of slurry 

over long distances with the lowest exposure to sea conditions. 

Once placed on the bottom, they are seldom moved by normal 

wave climates. Tropical storms may cause movement of 

submerged pipelines if insufficiently anchored. 

Submerged reefs can present additional challenges for pipeline 

transportation of slurries. In some cases, submerged pipelines can be suspended above the 

bottom with the use of concrete-filled plastic collars wrapped around the pipe as depicted here. 

In more severe circumstances, submerged pipelines may be prohibited altogether, and floating 

lines would become necessary. With floating lines, some anchoring devices will be necessary 

to keep the line in place. These anchors could subject the sea bottom to greater exposure than 

the concrete-filled plastic collars. 
MMS Study 2010-010 

23 

Shore pipelines are used on shore to transport slurry over 

land. They are normally configured in relatively short pieces 

of 12 m or so to facilitate transport by truck over the road. 

As material is deposited at the end of the shore pipeline, the 

terminus, the sediments are managed to grade. Once 

sufficient material has been deposited for this 12-m section 

of fill, another pipe is added and connected to the end of the 

line. These connections are made by flanges or telescopes. 

This picture depicts a flanged connection on a 32-in. 

diameter pipeline. 

Installation and removal of pipelines are an important piece of the mobilization and 

demobilization effort. The three major categories of pipelines (floating, submerged, and shore) 

may commonly be installed and ready before the dredge arrives on site. Submerged lines are 

placed on the sea bottom in favorable sea conditions. The floating lines are connected via riser 

pipes to the submerged line and anchored in position awaiting the arrival of the dredge. These 

operations require people, boats, barges, and cranes to make these pipelines ready for delivery 

of sediment. The shore pipelines are placed at a convenient location on shore and made ready 

and available for adding at the end of the pipeline when the fill crew is ready for them. The 

shorelines can be delivered to the shore locations by truck, by barge, or both. The submerged 

pipelines are commonly towed to the site in lengths of 244 to 

305 m in rafts4

. 

The floating lines can be towed into position, or oftentimes they 

are broken down in smaller segments, stored, and transported 

on a barge. Upon arrival on a job site, they can be 

reassembled. 

Depths of water required for pipeline 

installation will vary with the project 

specifics. Conventional equipment will likely need a water depth of 

1.8 to 2.4 m to accommodate the barge and/or tender boat that is 

used to work with the pipelines. Water depths that exceed 12 to 15 m 

will require extra measures to protect the submerged line during 

placement and removal. 

Booster applications are becoming more common as borrow areas 

get farther from the placement sites. Boosters are placed in the 

pipeline at a point between the dredge and the pipe terminus. If the booster must be placed 

offshore, it may commonly be placed at the downstream end of the floating pipe, just ahead of 

the riser pipe. In the case where a booster is placed behind a section of submerged pipeline, a 

riser will leave the bottom, attach to the intake side of the booster, 

and then from the discharge of the booster back through a riser 

pipe to another section of submerged line or to another line. In 

some cases, there may be multiple boosters placed in the line to 

provide the necessary transport energy for the sediment slurry. 

 

4

 A raft is a series of pipes, usually six to eight, tied together at several locations along their length for long distance transport over a 

water body. 
MMS Study 2010-010 

24 

2.1.5 Turbidity Sources During Dredging 

Turbidity sources during dredging are to be expected. The primary sources of turbidity will be 

around the cutterhead and the suction mouth. Other areas will be in the vicinity of the swing 

wires as they drag along the sea bottom and anchors as they are placed, set, or moved. 

Another area is sediment that may be washed from the decks during cleaning or rain events. 

Turbidity around the cutterhead occurs as the agitation and scouring of the sediments around 

the cutter take place. As mentioned earlier, spillage is the material that is actually impacted by 

the cutter or suction but does not enter the flow regime in the pipeline. It falls back to the 

seafloor either immediately with coarse material or migrates away from the area with high 

currents and/or very fine sediment. Another significant source of turbidity is the action of the 

reverse flow carrying sediment from the pipeline when the pumping ceases. On many 

occasions throughout the day, the dredge must cease pumping for operational or repair issues. 

When this occurs, there is a natural emptying or back flushing of the pipeline through the 

suction mouth in which it entered. This creates a plume around the suction mouth. 

Ancillary operations usually involve boats and barges. Propeller wash in the vicinity of the sea 

bottom is the most common cause of turbidity around the ancillary operations. 

Placement areas are another significant source of turbidity. Effluent run-off from the discharge 

operation carries fine particles back to the receiving water body. These fine particles will be 

carried downstream for a distance that is a function of the grain size and current velocity. 

Types of containment include passive approaches such as extending the length of training dikes 

along the shore to provide longer settling distances. Often these are difficult to maintain due to 

sea conditions, tidal fluctuations, and erosion of the base 

of the levee due to the slurry itself. Other, more 

aggressive approaches have involved building cells along 

the shoreline with a weir to enhance settling within the cell. 

These cells are more difficult to prepare and require a 

larger, more extensive shore base of equipment. In many 

cases, these cells trap very fine material that may be 

considered less suitable shore renourishment material. 

2.2 HOPPER DREDGES 

Hopper dredges are commonly used in offshore conditions where exposure to sea conditions 

can adversely impact productivity and efficiency of other types of dredges. They are often 

configured like a ship with a cargo hold designed for dredged material. 

They are equipped with one to three dragarms, which are pipe 

structures suspended down the side of the hull to the seafloor. On one 

vessel, the USACE’s Wheeler, there is a dragarm that extends through 

the keel of the vessel to the seafloor. Dredged material is removed 

from the bottom through these dragarms and placed in the cargo hold 

of the vessel for transport. The vessel transports the material to a 

remote location for discharge through the bottom of the hull or for 

discharge from the hull through a pipeline. Once the vessel is emptied, 

it returns to the dredging location to repeat the loading process, thereby 

completing a dredge cycle. A dredge cycle includes the loading phase, 

which may incorporate multiple turns, the sail to the discharge location, the discharge phase, 

either pump-out or bottom dump, and then sailing back to the dredging location. 
MMS Study 2010-010 

25 

2.2.1 Dredging Equipment 

There are many aspects of a hopper dredge that are critical to the operations and effectiveness 

of the vessel as a dredge. The dredge is equipped with dragheads, which are attached to the 

end of the dragarm. These dragheads are designed for many different applications and types of 

material. Since this paper focuses on sand ridges and shoals, 

we will limit the discussion to sand and granular types of material. 

The excavation of sand from the seafloor with the application of a 

draghead is primarily a combination of cutting the sand with 

knives or teeth and/or waterjets and/or scouring the sand with the 

passing of water over the sand into the draghead. Most 

dragheads are made up of several major components. These 

are the helmet, the visor, the teeth, water-jets, the trunnion pin, 

and water-flap. On some projects, dragheads are fitted with 

“bomb bars” to exclude large unexploded ordnance (UXO), or 

munitions and explosives of concern (MEC). In recent years, the 

addition of a turtle deflector has been added to reduce the 

mortality rate of turtles in the dredge area. 

Some types of dragheads are designed for 100% scouring, while 

others are designed primarily for cutting with a smaller benefit from scouring. The application of 

teeth in a draghead is augmented with the use of a water-flap, which acts as a lever arm behind 

the draghead to force the teeth into the sand. As water flows under the water-flap at increasing 

velocity, the Venturi effect5

 pulls the visor of the draghead down, thereby leveraging or forcing 

the knives or teeth into the seafloor. Water-jets are also used to more efficiently remove sand 

from the seafloor. The jets are high velocity streams of water directed vertically downward into 

the sediment to inject water into the pores between the sand particles. This injection separates 

the sand particles and places them into suspension to be removed by the draghead as it passes 

over. The pressure of the jet water entering the draghead may range from 70 to 200 psi, 

depending upon the application. Once the sediment enters the draghead, it flows up the 

dragarm to the centrifugal dredge pump, where it is propelled into the hopper. This process 

continues until the load in the hopper dredge reaches a maximum legal or practical draft of the 

vessel. This load is optimized by allowing water to leave the cargo area via valves and water 

ports located in and around the hopper void, and leaving the sand in the hopper. In most cases, 

fines are carried along with the overflowing water back into the sea, either over the side of the 

vessel or through the bottom of the hull. On most projects in the United States today, water 

leaving the vessel passes through a matrix of screens to capture evidence of a “biological take.” 

The screens are periodically inspected by certified biologists in accordance with permit 

requirements placed on some projects. 

 

5

 The Venturi effect is the fluid pressure that results when an incompressible fluid flows through a constricted section of pipe. The 

Venturi effect may be derived from a combination of Bernoulli's principle and the equation of continuity. The fluid velocity must 

increase through the constriction to satisfy the equation of continuity, while its pressure must decrease due to conservation of 

energy: the gain in kinetic energy is supplied by a drop in pressure or a pressure gradient force. The limiting case of the Venturi 

effect is choked flow, in which a constriction in a pipe or channel limits the total flow rate through the channel, because the local 

pressure in the constriction cannot drop below the vapor pressure in a liquid or exceed the speed of sound in a gas. Using 

Bernoulli's equation in the special case of incompressible fluids (such as the approximation of a water jet), the theoretical pressure 

drop (p1 − p2) at the constriction would be given by . The Venturi effect is named after Giovanni Battista Venturi, 

1746–1822, an Italian physicist. 
MMS Study 2010-010 

26 

2.2.2 Hopper Dredge Loading 

Hopper dredges maneuver through a borrow area removing 9 to 46 cm of material over the 

width of a draghead that may vary from 1.5 to 4 m in width. They may trail6

 at speeds of 1 to 

3 knots, depending upon the application. Positioning of the vessel is universally provided via 

GPS described above. Accuracy in the horizontal plane at the surface is commonly submeter. 

Accuracy on the seafloor depends upon the level of monitoring available on the vessel. 

Dragarms and dragheads do not naturally hang vertically as they ride along the seafloor. They 

move back and forth with the influence of the seabed. If a vessel is not equipped with 

angle-measuring equipment on the dragarm sections, the actual locations of the dragheads will 

be extrapolated based only upon the location of the hull. 

In the United States today, hopper dredges are required to maintain the “Silent Inspector” to 

work on USACE projects or permit projects. This monitoring equipment automatically records 

and reports the following information to the USACE: 

 Dredging position; 

 Dredging depth; 

 Vessel displacement; 

 Cargo tonnage; 

 Tons of dry solids; 

 Vessel speed; 

 Vessel heading; 

 Dredge cycle time; 

 Slurry flow-rate; 

 Slurry density; and 

 Vessel status (loading, sailing, dumping, and idle). 

As the hopper dredge trails through the borrow area, it is steering toward the available bank of 

material. Narrow, restricted, and small borrow areas require significant maneuvering that 

adversely impacts the productivity of the dredge. Turning of the dredge in small diameter circles 

requires temporary suspension (4 to 9 minutes) of dredging, thereby increasing cost. An ideal 

borrow area is one of sufficient length to match the required loading time divided by the 

optimum trailing speed divided by 2 times 1.25. For example, if a ship requires approximately 

60 minutes to achieve its full load and it trails at approximately 2 knots, according to this 

formula, a borrow area length of 2,316 m would be an optimum dimension. Borrow areas that 

incorporate the production needs of the hopper dredges will result in more efficient pricing to the 

customer. 

In some cases, the hopper dredge may be required to crab along the trail length. This would be 

similar to an airplane coming in for a landing on the runway when you see the longitudinal 

alignment of the plane in misalignment of the runway due to these side forces. Hopper dredges 

are affected by winds and current, resulting in side forces that must be overcome by the 

propulsion systems aboard the vessel. These impacts reduce the efficiency of the dragheads, 

and in some cases, require the elimination of the use of one or the other dragheads due to the 

side forces on the vessel. 

Sand ridges and shoals are often found in the vicinity of protected hard bottom resources. 

These protected areas should be programmed into the positioning system of the hopper dredge 

 

6

 Trailing is the term used to define the action of the hopper dredge as it is removing material in the borrow area. 
MMS Study 2010-010 

27 

so they are readily available and visible by the ship’s master, mates, and operators. The areas 

can be easily avoided in most circumstances with the application of this technology. As for 

overflow impacts, hopper dredges incorporating the load optimizing procedures will always allow 

water and fines to overflow from the hopper during the loading phase. The amount of fines 

overflowing with the water is primarily a function of the grain size of the material and the 

relationship of the infill rate to the settling surface area in the hopper. The smaller the settling 

area, the larger the percentage of the fines that will escape overboard. The greater the 

flow-rate into the hopper with any given settling area, the greater the percentage of fines that 

will escape overboard. To retain fines or to “top off” the load, some operators will reduce the 

inflow from one or all dragarms to reduce the ratio of inflow to the settling area. 

2.2.3 Pump Ashore Operations 

If a hopper dredge is working a sand ridge or a shoal, it is likely involved in a mining effort of 

some sort to beneficially use the material in a shoreline restoration project or reclamation area. 

If so, the dredge will likely be rehandling the material from its cargo hold to its ultimate location 

onshore through a pipeline. This is considered a direct pump-out effort and involves a more 

extensive use of additional equipment. A direct pump-out operation may incorporate some or all 

of the following equipment: 

 Anchorage by anchors or other suitable equipment; 

 Floating pipeline (hose) extending from the bow of the ship; 

 Booster(s) to assist with the discharge of the material to the shoreline; 

 Riser pipeline (described earlier); 

 Submerged pipeline (described earlier); 

 Shore pipeline, dozers, tractors, lights, and maintenance equipment located on shore; 

 Tug to assist the connection of the dredge to the pipeline; 

 Mono-buoy to assist with the connection of the pipeline; 

 Crane barge for working with floating equipment in the vicinity of the project; 

 Crew boat(s) for moving people and equipment around the site; and 

 Survey boat(s) to monitor progress and productivity of the dredge. 

Anchorage areas, not withstanding the specific project requirements, will commonly be located 

at a point closest to the required fill area at the contour that incorporates the draft of the loaded 

vessel plus the tide variation and the expected sea conditions. For example, if a hopper dredge 

is drafting 6.7 m of water when it is loaded, the pump-out location may be located in 

approximately 8.2 to 8.5 m of water. 

The operators will always look at the slope of the contouring seabed. In some cases, very long 

shallow slopes may indicate 1,000:1, where each additional foot of depth may significantly 

increase pipeline lengths. Those anchorage location decisions include optimizing the 

relationships between load and draft depths and varying discharge distances. 

Once the pump-out location is established, an anchoring system must be installed. Often a 

mono-buoy is utilized to anchor the end of the hose and make it available for the hopper dredge 

upon arrival at each pump-out event, often several times a day. This mono-buoy can be 

secured to the bottom with a three-point anchor system that may extend out from the 

mono-buoy several hundred feet. In other cases, the hose can have a small anchor attached to 

the end that is retrieved by the assist boat when the hopper dredge comes into position. The 

control of the pump-out hose is transferred to the bow of the hopper dredge, where the 
MMS Study 2010-010 

28 

connection is made. At the completion of the pump-out sequence, control of the hose is 

transferred back to the assist boat or simply dropped to the seafloor. The other end of the hose 

is normally connected to either a riser pipe leading to a submerged steel pipeline laying on the 

seafloor, or it connects to a booster application if one is incorporated into the system. 

Once the connection is made between the hopper dredge and the hose, the pump-out process 

begins. The dredge operator initially pumps water through the pipeline until water is received at 

the terminus of the discharge line. This forces any air that 

may be in the line out through an air valve located just 

upstream of the submerged pipeline. This keeps air out of 

the subline so it does not inadvertently rise to the surface or 

lift from the seafloor. Once the discharge line is stabilized 

with water, the operator begins to allow sand into the system 

from the cargo hold of the dredge. Jet water inside the 

hopper facilitates the mixing of the sand with water and its 

entry into the slurry 

pipeline. This process 

will continue with the operator throttling the sand into the 

system to the limit of the system’s horsepower to handle 

the velocity and density. Once the hopper hold is 

sufficiently evacuated, the operator will likely flush the 

floating hose with water for a few minutes, and possibly 

the submerged line depending upon the type of material, 

the project conditions or the plans for future use of the line 

in this particular location. Once the flushing action is 

completed, the dredge disconnects from the hose and 

returns to the dredging area for another load. This cycle repeats itself until the fill at this location 

has been completed. 

Turbidity around the hopper dredge operations occurs in a few locations. The most significant 

contribution to turbidity occurs as a result of the load-optimizing process. Overflowing of the 

hopper is intended to maximize the load of sand in the hopper. This process will carry fines 

overboard that will be entrained in the water column at some level. Some hopper dredges 

overflow below the surface of the water, some overflow at the surface, and some overflow at 

both locations. Another area of turbidity exists around the dragheads as they move through the 

sediment. Not all sediment impacted by the draghead is removed by the suction capacity. 

Incorporating turtle-excluding devices (TEDs) increases the interaction of the draghead on the 

seafloor with the sediments, thereby increasing turbidity around the dragheads. Another area of 

turbidity exists when the propulsion of the hopper dredge impacts the seafloor, stirring up fines 

laying on the sea bottom. The final significant area of turbidity exists around the fill area as the 

water is returning to the sea from the fill operations. 

2.3 OTHER OFFSHORE DREDGING EQUIPMENT AND TECHNIQUES 

2.3.1 Dustpan Dredges 

The dustpan dredge is ideal for the excavation of granular sediment. The first use of the 

dustpan technology in the offshore mining environment was the dredge Beachbuilder7

, 

designed, built, and operated by The Bean Companies in New Orleans, Louisiana. This 

 

7

 The Beachbuilder was redesigned and modified as a cutterhead dredge, renamed the Ohio, and mobilized to the Middle East in 

2008 by Great Lakes Dredge and Dock Company. 
MMS Study 2010-010 

29 

photograph of the dustpan dredge, Wallace McGeorge, was also designed, built, and operated 

by The Bean Companies until it was sold to and renamed by the Pine Bluff Sand and Gravel 

Company in 1991. 

Dustpan technology relies upon agitation of the bottom sediments through the use of water jets 

near the suction head to excavate and remove sand from the seabed. This technology works 

well in sediments that are relatively clean, free from silt, 

mud, and shell or shell fragments. 

The dustpan-operating principle is based upon winching 

itself forward into a bank of sand. The two large 

privately owned dustpans have a suction head that is 

rectangular shaped approximately 9 to 10 m wide and 

approximately 46 to 60 cm high. A row of jets injecting 

high velocity water streams into the sediment are along 

the top of the dustpan head, and in some cases, along 

the bottom of the head. The dredge pulls itself forward, 

allowing the jets to collapse, slurrify, and remove the 

sediments that fall in front of the suction mouth. Bank heights of 1.2 to 2.4 m may be removed 

in each pass, requiring multiple passes in higher banks of material. 

The Beachbuilder, the larger American dustpan dredge, was equipped with six anchors, three 

forward and three aft, for positioning itself offshore. The Wallace McGeorge, the smaller 

dustpan dredge, utilizes two forward anchors and stern propulsion for positioning on the 

Mississippi River, its sole operating environment. 

Except for the operating procedures and the longer floating hose that would be required to 

accommodate the larger working area of the dustpan, most other ancillary operations in the 

offshore environment are similar to the cutterhead dredge operations described above. 

2.3.2 Punaise 

The Punaise or “thumbtack,” as it was commonly referred to, is a Dutch-designed system from 

the 1980’s intended to mine sand in either the offshore or inland environments. The technology 

has been slow to catch momentum primarily due to the requirement of significant banks of sand 

to make it a productive device. It works on a similar principle to that 

described in Section 2.1.3. The Punaise is composed of a watertight 

housing containing the dredge pump, motor, and ballast tanks. It is 

connected to the shore station via an umbilical that consists of control 

connections, power supply, and a slurry discharge line. While in 

operation, the Punaise rests on the bottom of the seabed and pumps 

sediment without impact to surface vessels. Once positioned at the 

appropriate location for sinking to the bottom, the ballast tanks are 

filled, and the Punaise settles to the bottom. Water jet nozzles are 

then activated, which allow the vertical support to settle into the sand 

bottom so the dredging process can begin. As material is removed, a 

pit is formed with the Punaise located at the lowest point. The 

submerged machine excavates by means of hydraulic erosion and agitation. The Punaise 

transports the sand ashore via a small diameter pipeline, usually less than 20 in. Anchors, 

wires, and boats are still a necessity for this application. 
MMS Study 2010-010 

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MMS Study 2010-010

31 

3.0 PHYSICAL IMPACT PRODUCING FACTORS ASSOCIATED WITH 

SAND MINING ON SHOALS OFFSHORE MARYLAND 

(Mark R. Byrnes – Applied Coastal Research and Engineering, Inc.) 

As described in Section 2.0, sand dredging on the continental shelf almost exclusively employs 

hydraulically-operated equipment for excavating and transporting sand resources from the 

Federal OCS to nourish onshore beaches (Herbich, 1992). In general, the distance from the 

borrow site to the beach determines the dredging and sand transport method to be used (Louis 

Berger Group, 1999). The most commonly used methods are a hydraulic cutter-suction dredge, 

which pumps fluidized sand through a pipeline to the beach, and a hopper dredge, with two 

dragheads and a hopper. When the hopper is filled, the dredge lifts the dragheads and 

transports the sand to shore for unloading. 

Each dredging method generally is employed based on project site distance from the borrow 

source. Cutter-suction (versus cutterhead) dredges and pipelines are used primarily for 

transport distances of less than about 5 to 6 km, although the distance can be larger depending 

on sea conditions. These dredges are used most prominently throughout the industry, having a 

rotating cutter surrounding the intake end of the suction pipe (Section 2.0). The method of 

sand extraction and transport is quite efficient, resulting in about 90% to 95% of excavated sand 

reaching the beach. Limiting environmental factors for the cutter-suction dredge for economic 

operations include a maximum water depth to dredge of about 30 m, a maximum cut width of 

about 175 m, a maximum ocean wave height of 2 m, a maximum swell wave height of 1 m, and 

maximum cross currents of about 2 knots (Louis Berger Group, 1999). 

Hopper dredges are the preferred methodology when borrow sources are greater than 6 km 

from the beach. These dredges are self-propelled and suitable for open ocean sand mining and 

loading a self-contained hopper while the ship is underway. Loading occurs as the ship moves 

ahead at a speed of about 2 to 3 knots. Unloading can be completed via bottom discharge, 

pump discharge, or mechanical removal. Some main advantages of this dredging method are 

1) it is a self-propelled, independent operation; 2) loads can be transported over long distances; 

3) production rate is high; and 4) operations can take place in relatively deep water and higher 

sea-state conditions. For economical operations, maximum practical water depth is about 46 m. 

Maximum wave heights can be about 4.6 m, and cross-currents of about 3 knots are tolerable. 

Peak sailing speed is about 17 knots, and minimum operating water depth is about 4.6 m. 

The purpose of this section is to provide a qualitative evaluation of operational factors potentially 

influencing shoal morphology and biological communities on the Federal OCS offshore 

Maryland (addresses components of the second and fourth questions in Section 1.2). Primary 

areas of concern include specific locations for sediment removal and the quantity of sand being 

removed, the likelihood of sediment suspension/dispersion associated with sand excavation 

from shoals, the magnitude and extent of sand deposition resulting from suspension/dispersion 

during dredging, and any other seafloor disturbances that may occur as a result of dredging. 

3.1 EXCAVATION QUANTITY AND SEDIMENT REMOVAL 

USACE (2008) presents a comprehensive evaluation of potential environment factors 

influencing shoal habitat and fauna. Sediment removal from portions of selected shoals was 

evaluated based on required sand quantities for beach nourishment through 2044 and 

sedimentologic characteristics of shoal deposits. Based on beach nourishment project 

performance since 1998 for the Ocean City, Md., beaches, USACE (2008) determined that 
MMS Study 2010-010

32 

approximately 5.2 to 11.5 million cubic meters (x 106 m3) (6.8 to 15 million cubic yards [Mcy]) of 

sand would be required to maintain beach stability through 2044. The challenge was to identify 

offshore sand deposits that could supply this quantity of material in a manner sensitive to 

fisheries and the environment. 

The availability of beach-quality sand from the continental shelf throughout the study area has 

been evaluated by the MGS, MMS, USACE, and other investigators (Field, 1980; Louis Berger 

Group, 1999; Conkwright et al., 2000; MMS, 2003; USACE, 2008). Although sand deposits 

occur in a variety of features on the shelf, shore-detached shoals were found to contain large 

quantities of sand suitable for beach nourishment. Furthermore, USACE studies of the ebb-tidal 

shoal at Ocean City Inlet identified sand suitable for beach nourishment; however, deposits 

typically were more heterogeneous than those associated with offshore shoals. Conversely, 

MGS found that shore-attached ridges typically contain fine sand and mud, which generally is 

considered unsuitable as beach fill. MGS also evaluated sand characteristics associated with 

flat seafloor areas (sheet sands) and found variable sand thickness, often only several feet, 

generally overlaying fine-grained deposits unsuitable as beach fill. Such depositional 

characteristics make sheet sands difficult to dredge. Lastly, subsurface paleochannel fill 

deposits are limited in size and extent, and they are generally buried under relatively thick 

fine-grained deposits. Again, these kind of sand borrow sites are time consuming to dredge and 

often result in significant environmental impacts. 

3.1.1 Sediment Availability 

USACE (2008) performed a detailed analysis of potential candidate shoals offshore Ocean City 

from which sand might be available for beach nourishment. Nine shoals were identified from 

which approximately 316 x 106

 cu m (413 Mcy) was designated as beach quality sand (see 

Table 4-1 in USACE [2008]). This sand volume is far greater than beach nourishment needs at 

Ocean City for the foreseeable future. As such, each identified shoal was evaluated by USACE 

to determine whether any engineering, economic, or environmental factors might favor a 

specific borrow site. Based on this analysis, Weaver Shoal, Isle of Wight Shoal, and Shoal A 

were identified as having high-potential for providing beach-quality sand (see Figure 1.6). 

Weaver and Isle of Wight shoals are located approximately 13 km from the center of Ocean City 

beaches. Offshore sand resource evaluations completed by MGS personnel determined that 

approximately 63 and 54 x 106

 cu m (82 and 71 Mcy) of beach quality sand, respectively, were 

available from each shoal (USACE, 2008). Shoal A is located farthest offshore (about 15 km 

from Ocean City) and contains the least amount of beach quality sand (about 28 x 106

 cu m 

[37 Mcy]). These data were further analyzed in USACE (2008) to better describe the location 

and quantities of beach quality sand deposits for each of these shoals (designated “acceptable” 

on Figures 1.7, 1.8, and 1.9). Approximately the southern half of Weaver Shoal was 

determined to be acceptable as beach fill, the volume of which was estimated at 20.1 x 106

 cu m 

(26.3 Mcy) relative to the 18-m depth contour (National Geodetic Vertical Datum [NGVD], 

USACE, 2008) (Figure 1.7). For Isle of Wight Shoal, the north-central portion of the shoal 

complex (“Acceptable” and “Marginal” areas Figure 1.7) was determined to contain 

approximately 23.5 x 106

 cu m (30.7 Mcy) of beach fill relative to the 17-m (NGVD) depth 

contour. At Shoal A (Figure 1.9), only the northwestern portion of the shoal complex was 

classified as acceptable for beach fill, but northeastern portions of the shoal were marginally 

acceptable, resulting in about 8.1 x 106

 cu m (10.6 Mcy) of sand relative to the 17-m (NGVD) 

depth contour. Based on their analysis, USACE (2008) determined that approximately 

51.7 x 106

 cu m (67.6 Mcy) of beach quality sand is available to nourish Ocean City beaches. 

This volume is about 4.5 times the amount required through 2044. Geological characteristics 
MMS Study 2010-010

33 

for each area are provided in USACE (2008). This information was used to complete numerical 

modeling of seafloor elevation changes as documented in Section 5.0. 

3.1.2 Sediment Removal 

Concerns regarding sand removal effects on physical processes and biological habitat 

prompted USACE (2008) to recommend restrictions regarding sand dredging along shoal crests 

shallower than 30 feet. Based on shoal characteristics listed in USACE (2008), four potential 

dredging scenarios were developed for evaluating changes in physical processes on shoals 

containing acceptable sand deposits for beach nourishment along Ocean City beaches. 

Specific sediment removal scenarios for this study include 

 dredging a hole over a designated area on the shoal; 

 dredging the leading edge of a shoal; 

 dredging the trailing edge of a shoal; and 

 dredging in a striped pattern to facilitate recruitment of benthic invertebrates into dredged 

areas. 

Removal of sediments from borrow sites can alter seabed topography, creating pits that may 

refill rapidly or cause detrimental impacts for extended periods of time. The term borrow site 

can be misleading because often material is returned only by natural sediment transport 

processes. Many years have been required for some offshore borrow sites to refill to 

pre-dredging profiles (Wright, 1977), whereas other borrow sites have been known to remain 

well-defined years after dredging (Marsh and Turbeville, 1981; Turbeville and Marsh, 1982; 

USACE, 2008 [Annex B3]). Intentionally locating borrow sites in areas of rapid deposition may 

dramatically reduce the time for refilling (Byrnes and Groat, 1992; Van Dolah et al., 1998). In 

general, shallow dredging over large areas causes less harm than dredging small but deep pits, 

particularly pits opening into a different substrate surface (Thompson, 1973). Deep pits also 

can hamper commercial trawling activities and harm level-bottom communities (Thompson, 

1973). If borrow pits are deep, current velocity is reduced at the bottom, which can lead to 

deposition of fine particulate matter, and in turn, a biological assemblage much different in 

composition than the original. Recovery of the physical environment and benthic assemblages 

to pre-dredging conditions will probably take decades for a deep pit dredged 3.6 km offshore 

Coney Island (Barry A. Vittor & Associates, Inc., 1999). 

Seabed topography and benthic communities can be altered when sediment is removed by 

dredging bathymetric peaks such as ridges or shoals rather than level sea bottoms or 

depressions. Numerous benthic organisms and fishes inhabit offshore shoal areas, but 

specifics regarding species, assemblages, and ecological interrelationships between the 

topographic features and associated biota are not well known. Potential long-term physical and 

biological impacts could occur if dredging significantly changes the physiography of shoals. 

However, Burlas et al. (2001) monitored borrow sites with bathymetric high points off northern 

New Jersey and found that essentially all infaunal assemblage patterns recovered within 1 year 

after dredging disturbance, except recovery of average sand dollar weight and biomass 

composition, which required 2.5 years. 

For the dredging scenarios listed above, perhaps the most desirable location for dredging is 

associated with areas of net long-term deposition. Extracting sand from a depocenter implies 

that recovery or infilling processes would proceed in a way consistent with natural long-term 

depositional processes for the borrow area (Byrnes and Groat, 1992; Van Dolah et al., 1998). 

Typically, this refers to the leading or downdrift margin of a shoal. Determining the magnitude 
MMS Study 2010-010

34 

and extent to which long-term seafloor changes occur on and adjacent to shoals requires one to 

accurately evaluate sequential bathymetric surveys. For Weaver Shoal, Isle of Wight Shoal, 

and Shoal A, bathymetric data collected by NOAA between 1975 and 1978 were compared with 

USACE bathymetric data collected in 2002 to document net change. 

Figure 3.1 records net changes in seafloor elevation relative to shoal morphology. Blue colors 

represent deposition, and yellow to red colors represent erosion. Colored polygons illustrate the 

locations of potential dredging sites where scenarios listed in Table 3.1 were simulated (see 

Section 5.0). Approximately 1.1 to 1.7 x 106

 cu m (1.4 to 2.2 Mcy) were extracted from each 

shoal. This quantity range was based on the history of beach fill needs for Ocean City and 

Assateague Island as extracted from similar shoals offshore Maryland (USACE, 2008). One 

primary observation is that the leading edge of Weaver Shoal can be identified clearly as an 

extensive depositional area along the southern margin of the shoal. Byrnes and Groat (1992) 

identified a portion of Ship Shoal (Louisiana) with similar depositional characteristics as an ideal 

location for a sand borrow site because dredging would occur in an area of active natural 

deposition, potentially minimizing long-term environmental damage. 

Table 3.1. Potential dredging scenario characteristics. 

Shoal Name Sub-Area Removal Type Excavation Depth 

(m) 

Removal Volume 

(x106 cu m) 

Crest Hole 3 1.3 

Weaver Crest Striped 4 1.7 

Leading edge Slice 2 1.4 

Crest Hole 2 1.5 

Isle of Wight Crest Striped 4 1.4 

Trailing edge Slice 2 1.7 

Trailing edge Hole 2 1.4 Shoal A Trailing edge Striped 3 1.1 

*Striped scenarios include five dredging strips 50-m wide and 50-m apart. 

Bathymetric change data also suggest that the eroding portion of a shoal’s trailing edge may be 

an area to avoid. Because this part of the shoal often is net erosional, the area provides a 

source of sediment to depositional regions of the shoal (Figure 3.1). As such, dredging in these 

areas may have a direct impact on natural erosion processes that source downdrift 

depocenters, thereby disrupting natural shoal evolution. As a result, polygon locations for 

simulated dredging illustrated on Figure 3.1 were sited within acceptable sand resource areas 

to avoid active erosion zones. Shoal A was the only sand borrow area where this could not be 

completely avoided. 

Borrow site geometry was also considered when assessing physical impact producing factors 

for each shoal. The intent was to design dredging scenarios that are reasonable in terms of 

dredging requirements (e.g., dredging distance and depth) and avoid concerns regarding the 

physical and biological environmental impacts of the dredging process. For instance, when 

dredging a hole on the shoal, it was important to avoid deep sand borrow pits because negative 

environmental impacts are known to be associated with this type of dredging (Thompson, 1973; 

Byrnes et al., 2000; Byrnes et al., 2003; Kelley et al., 2004; Hammer et al., 2005). As such, 

dredging depths for various simulations never exceeded 4 m, and the area over which dredging 

simulations occurred was large. Furthermore, dredging in a striped pattern overreach of the 

shoals was simulated because studies suggest that this procedure may facilitate recruitment of 
MMS Study 2010-010

35 

Figure 3.1. Areal extents for selected dredging scenarios for each shoal relative to seafloor 

changes recorded between 1975/1978 and 2002. 
MMS Study 2010-010

36 

benthic invertebrates into the dredged borrow site (USACE, 2008). Increased surface area 

associated with this dredging technique also is expected to promote transport and redistribution 

of sediment after initial sand excavation, leading to a more uniformly distributed infilling process. 

3.2 SEDIMENT SUSPENSION/DISPERSION (TURBIDITY) 

Dredging causes suspension of sediments, which increases turbidity over the bottom. Turbidity 

undergoes dispersion in a plume that drifts with water currents as suspended sediments from 

dredging settle. The extent of suspension/dispersion depends on a multitude of factors, 

including the type of dredging equipment techniques for operating the equipment, amount of 

dredging, thickness of the dredged layer, sediment composition, and sediment transport 

processes. Although turbidity plumes associated with dredging often are short-lived and affect 

relatively small areas (Cronin et al., 1970; Nichols et al., 1990), resuspension and redispersion 

of dredged sediments by subsequent currents and waves can propagate dredge-related 

turbidity for extended periods after dredging ends (Onuf, 1994). Biological responses to 

turbidity depend on all of these physical factors, coupled with the type of organism, geographic 

locations, and the time of year. In the case of sand dredging from offshore shoals for beach 

nourishment, turbidity plumes at the borrow site are virtually nonexistent due to rapid settling of 

sand-sized particles, resulting in minimal if any sedimentation impacts relative to background 

transport processes (Louis Berger Group, 1999). 

Herbich and Brahme (1991) and Herbich (1992) reviewed sediment suspension caused by 

existing dredging equipment, and discussed potential technologies and techniques to reduce 

suspension and associated environmental impacts. In general, cutterhead suction dredges 

produce less turbidity than hopper dredges. A cutterhead suction dredge consists of a rotating 

cutterhead, positioned at the end of a ladder, which excavates the bottom sediment. The 

cutterhead is swung in a wide arc from side-to-side as the dredge is stepped forward on pivoting 

spuds, and excavated material is lifted by a suction pipe and transferred by pipeline as slurry 

(Hrabovsky, 1990; LaSalle et al., 1991). Sediment suspension is caused by rotating action of 

the cutterhead and swinging action of the ladder (Herbich, 1992). Well-designed and properly 

operated cutterhead dredges can limit sediment suspension to the lower portion of the water 

column (Herbich and Brahme, 1991; Herbich, 1992). Turbidity can be reduced by selecting an 

appropriate cutterhead for a given sediment, determining the best relationship between 

cutterhead rotational speed and hydraulic suction magnitude, establishing a suitable swing rate 

for the cutterhead, and using hooded intakes, although these conditions are rarely achieved 

(Herbich, 1992). Measurements around properly-operated cutterhead dredges show that 

suspended sediments can be confined to the immediate vicinity of the cutterhead and dissipate 

rapidly, with little turbidity reaching surface waters (Herbich and Brahme, 1991; LaSalle et al., 

1991; Herbich, 1992). Maximum suspended sediment concentrations typically occur within 3 m 

above the cutterhead and decline exponentially to the sea surface (LaSalle et al., 1991). 

Suspended sediments in near-bottom waters may occur several hundred meters laterally from 

the cutterhead location (LaSalle et al., 1991). 

A hopper dredge consists of one, two, or more dragarms and attached dragheads mounted on a 

ship-type hull or barge with hoppers to hold material dredged from the bottom (Herbich and 

Brahme, 1991). As the hopper dredge moves forward, sediment is hydraulically lifted through 

the dragarm and stored in hopper bins on the dredge (Taylor, 1990; LaSalle et al., 1991). 

Hopper dredging operations produce turbidity as the dragheads are pulled through bottom 

sediment. However, the main source of turbidity during hopper dredging operations is sediment 

release during hopper overflow (Herbich and Brahme, 1991; LaSalle et al., 1991; Herbich, 
MMS Study 2010-010

37 

1992). A plume may occasionally be visible at distances of 1,200 m or more (LaSalle et al., 

1991). 

Much attention has been given to turbidity effects from dredging, although most reviews have 

concerned estuaries, embayments, and enclosed waters (e.g., Sherk and Cronin, 1970; Sherk, 

1971; Sherk et al., 1975; Moore, 1977; Peddicord and McFarland, 1978; Stern and Stickle, 

1978; Herbich and Brahme, 1991; LaSalle et al., 1991; Kerr, 1995; Newcombe and Jensen, 

1996; Wilber and Clarke, 2001). Turbidity effects may be less important in unprotected offshore 

areas for several reasons. Offshore sands tend to be coarser, with less clay and silt than 

inshore areas. The open ocean environment also provides more dynamic physical 

oceanographic conditions, which minimize settling effects. In addition, offshore organisms are 

adapted to sediment transport processes, which create scouring, natural turbidity, and 

sedimentation under normal conditions. Impacts should be evaluated in light of natural 

variability as well as high-level disturbances associated with such events as storms, trawling, 

and floods (Sosnowski, 1984; Herbich, 1992). Physical disturbance of the bottom and resulting 

biological impacts from dredging are similar to those of storms and trawling but at a much 

smaller spatial scale. The following suggestions from Hughes and Connell (1999) also are 

instructive regarding the complexities of analyzing effects of multiple stressors (broadly defined 

as natural or man-made disturbances). Long-term approaches are necessary to understand 

biological responses to multiple stressors because studying single events in isolation can be 

misleading. The effects of a particular disturbance often depend critically on impacts from 

previous perturbations. Consequently, even the same type of recurrent stressor can have 

different effects at different times, depending on history. Accordingly, when the added 

dimension of time is considered, the distinction between single and multiple stressors becomes 

blurred (Hughes and Connell, 1999). 

Turbidity from dredging can affect food availability for benthic organisms. Changes in light 

penetration and wavelengths due to turbidity can affect visibility and may be detrimental or 

beneficial, depending on whether an organism is predator or prey. Suspension and dispersion 

processes uncover and displace benthic organisms, temporarily providing extra food for 

bottom-feeding species (Centre for Cold Ocean Resources Engineering, 1995). Turbidity can 

interfere with food-gathering processes of filter feeders and organisms that feed by sight by 

inundation with nonnutritive particles. In addition to altered feeding rates, other biological 

responses to turbidity include reduced hatching success, slowed growth, abnormal 

development, tissue abrasion, and increased mortality (Wilber and Clarke, 2001). In general, 

egg and larval stages are more sensitive to turbidity effects than older life history stages. 

Finally, suspension and dispersion of sediments may cause changes in sediment and water 

chemistry as nutrients and other substances are released from the substratum and dissolved 

during dredging. For aggregate mining operations using hopper dredges, the far-field visible 

plume contains an organic mixture of fats, lipids, and carbohydrates from organisms entrained 

and fragmented during the dredging process and discharged with the overflow (Coastline 

Surveys Limited, 1998; Newell et al., 1999). Furthermore, dredging may produce localized 

hypoxic or anoxic conditions in the water column due to oxygen consumption of suspended 

sediments (LaSalle et al., 1991). However, one should not lose track of the fact that turbidity 

effects are expected to be less important in unprotected offshore areas. Offshore shoals tend to 

be coarser with less clay and silt than inshore deposits. The open ocean environment also 

provides more dynamic physical oceanographic conditions, which minimize settling effects. In 

addition, offshore organisms are adapted to sediment transport processes, which create 

scouring, natural turbidity, and sedimentation under normal conditions. 
MMS Study 2010-010

38 

3.3 SEDIMENT DEPOSITION 

Suspended sediments settle and are deposited nearby dredged offshore sand borrow sites. 

The extent of deposition and boundaries of biological impact are dependent on the type and 

amount of suspended sediments and physical oceanographic characteristics of the area. 

Deposition of sediments can suffocate and bury benthic biota, although some mobile soft 

bottom organisms are able to migrate vertically to the new surface (Maurer et al., 1986; Nelson, 

1988). Furthermore, sediment deposition can inhibit larvae of numerous invertebrate species 

that need hard surfaces to settle and develop (Thorson, 1966; Rogers, 1990). 

Dredging effects are not necessarily limited to the sand borrow site alone. Far-field impacts 

from suspension, dispersion, and deposition of sediments during dredging can be detrimental or 

beneficial. Johnson and Nelson (1985) found decreases in infaunal abundances and numbers 

of taxa at nondredged stations, although these decreases were not as extreme as those 

observed in the borrow site. McCaully et al. (1977; as cited by Johnson and Nelson, 1985) also 

observed that dredging effects can extend to other nearby areas and noted decreases in 

infaunal abundances, ranging from 34% to 70% at undredged stations within 100 m of a 

dredged site. Conversely, benthos may show increased biodiversity downstream from dredged 

sites (Centre for Cold Ocean Resources Engineering, 1995). In some areas, population density 

and species composition of benthic invertebrates increased rapidly outside dredged sites, with 

the level of enhancement decreasing with increasing distance from the dredged site up to a 

distance of 2 km (Stephenson et al., 1978; Jones and Candy, 1981; Poiner and Kennedy, 

1984). The enhancement was ascribed to release of organic nutrients from the dredge plume, a 

process known from other studies (Ingle, 1952; Biggs, 1968; Sherk, 1972; Oviatt et al., 1982; 

Coastline Surveys Limited, 1998; Newell et al., 1998, 1999). This suggestion was supported by 

records of nutrient releases from benthic areas during intermittent, wind-driven bottom 

resuspension events (Walker and O’Donnell, 1981), significant increases in water column 

nutrients from simulated storm events in the laboratory (Oviatt et al., 1982), and review of the 

literature, indicating that the response of species to resources released from sediments by 

periodic disturbance is a major restructuring force in infaunal communities (Thistle, 1981). 

Fishing may improve temporarily down current of a dredging site and continue for some months 

(Centre for Cold Ocean Resources Engineering, 1995). Additional far-field impacts can occur 

by resuspension, redispersion, and redeposition of fine dredged materials by wave and current 

actions long after dredging has been completed. However, one should expect turbidity effects 

to be less important in unprotected offshore areas, where sand and gravel are the borrow 

materials. The open ocean environment also provides more dynamic oceanographic conditions, 

which minimize settling effects. Furthermore, offshore organisms are adapted to sediment 

transport processes, which create scouring, natural turbidity, and sedimentation under normal 

conditions. 
MMS Study 2010-010

39 

4.0 EVALUATION OF BIOLOGICAL RESOURCES ASSOCIATED WITH 

SHOALS OFFSHORE OF THE MID-ATLANTIC BIGHT 

(Tim D. Thibaut – Barry A. Vittor & Associates, Inc.; Barry A. Vittor – Barry A. Vittor & Associates, Inc.; 

David B. Snyder – CSA International, Inc.; and Kenyon C. Lindeman – Florida Institute of Technology) 

Previous reviews concerning potential impacts of offshore sand mining (Research Planning, Inc. 

et al., 2001) suggested further investigation into the status of sand shoals as essential fish 

habitat (EFH) for federally managed species and their prey. At the time of that report, very little 

data were available on the ecological function of sand shoals for fishes or invertebrates. Since 

the Research Planning, Inc. et al. (2001) report was issued, information has been collected 

regarding fish and invertebrate utilization of sand shoals in the Mid-Atlantic Bight, particularly in 

the region offshore Delaware, Maryland, and New Jersey. In this section, available data are 

reviewed and used to characterize invertebrate and fish presence and abundance on shoals. 

Invertebrates relate directly to the concept of EFH because some such as longfin squid, surf 

clam, and ocean quahog are federally managed fishery species; and invertebrates form the 

forage base for benthic feeding fishes that are also federally managed. In addition, some 

invertebrate species form structures or engineer habitats that are used by fishes of varying life 

stages. In this section, invertebrates and the assemblages they form are profiled with emphasis 

on species composition, spatial distribution, substrate preferences, habitat forming (engineering) 

characteristics, capacity for recolonization following disturbance, and trophic relationships with 

fishes. Demersal and pelagic fish assemblages are characterized by species and life stage 

composition in relation to sand shoals in the Mid-Atlantic Bight. Occurrence of federally 

managed fish and invertebrate species designated by regional fishery management councils 

and field collections is also documented. To illustrate how sand shoals fit into the larger 

seascape with respect to ecological functions provided to fishes and during their life cycle, 

cross-shelf habitat matrices were constructed. Examples of cross-shelf utilization are presented 

and discussed for two demersal and two pelagic species. These examples along with field data 

on species composition are used to demonstrate that shoals contribute to spawning, feeding, 

shelter, and growth to maturity for numerous species managed under EFH legislation. 

4.1 INVERTEBRATES 

The Virginia Institute of Marine Science (VIMS) (2000) obtained physical and biological data of 

study area shoals and nearshore sediments during research cruises in 1998 and 1999. Grab 

sampling for infauna and sediments was conducted with a 0.044-m2

 Young grab. In 1998, 

grabs were collected across an area that included Fenwick, Weaver, and Isle of Wight shoals, 

and nearshore gravel and sand sheets north of the shoals near Indian River Inlet. In 1999, grab 

samples were collected only in the area of the shoals. 

Infauna of the study area also are characteristic of assemblages across much of the western 

Atlantic and Gulf of Mexico (Brooks et al., 2006), mostly including annelids, predominantly 

polychaetes, bivalves, and crustaceans, particularly amphipods. Ubiquitous taxa occurring 

across the study area include nonidentified oligochaetes and rhynchocoels, and the polychaete 

Spiophanes bombyx, a highly abundant taxon distributed worldwide. Another widespread group 

in the study area includes the polychaetes Aricidea ceruttii and A. catherinae, Brania 

wellfleetensis, Hemipodus roseus, Parapionosyllis longicirrata, Parougia caeca, Protodorvillea 

kefersteini, and Streptosyllis pettiboneae. These polychaetes are common inhabitants of coarse 

sand and gravel habitats throughout the Mid-Atlantic Bight (Byrnes et al., 2000, 2003). 
MMS Study 2010-010

40 

The raw abundance data from the 1998 to 1999 grab samples (VIMS, 2000) were obtained for 

this study. Spatial and temporal patterns for the infaunal community were examined using 

multivariate cluster analysis. The cluster analysis was performed on a similarity matrix 

constructed from a raw abundance data matrix consisting of taxa and samples. Except for the 

bivalves Astarte spp. and Tellina spp., taxa identified to a generic or higher level of identification 

were excluded from the matrix. After removal of incompletely identified and redundant taxa, the 

data matrix was constructed using those taxa that collectively contributed to 95% of the total 

abundance over all samples. This produced a data matrix of 57 taxa by 72 stations. To weight 

the contributions of common and rare taxa, raw counts of each individual taxon in a sample (n) 

were transformed to logarithms [log10(n+1)] prior to similarity analysis. The grab sample 

similarity matrix was generated using the Bray-Curtis similarity index (Bray and Curtis, 1957). 

The cluster analysis was performed using PRIMER v5 package (Clarke and Gorely, 2001). 

Seven groups of stations (Groups A through G) were resolved based on similarity of infaunal 

assemblages. Figure 4.1 presents the approximate locations of station groups (A through G) 

resolved from the cluster analysis of grab sample composition in the area of Fenwick Shoal, Isle 

of Wight Shoal, and Shoal A. An outlier station (X) with low abundance and taxa richness was 

located near the crest of Fenwick Shoal. Group A included one station on the crest of Fenwick 

Shoal and one station on Isle of Wight Shoal. Group B included two stations on the crest of Isle 

of Wight Shoal and two stations on the northeast portion of Fenwick Shoal. Group C included 

stations on or near the crests of Weaver and Isle of Wight shoals, and on the northeast portion 

of Fenwick Shoal. Group D included stations in the intershoal troughs on the lee sides of 

Fenwick and Weaver shoals, as well as two stations near Indian River Inlet. Group E included 

several stations on Weaver and Isle of Wight shoals. Group F is composed of 1998 stations 

primarily near the base of Fenwick Shoal and near Indian River Inlet. Group G contained the 

most stations of any of the seven groups, with these concentrated around the base of Fenwick 

Shoal, particularly on its northwest side, and extending to the nearshore area near Indian River 

Inlet. 

Species accounting for the observed assemblage differences among groups and within groups 

of stations (samples) were identified using the similarity percentage breakdown (SIMPER) 

procedure (Clarke and Gorely, 2001). SIMPER determines the average contribution of each 

taxon to characterizing a sample group or discriminating between pairs of sample groups. 

Considering the average abundance of species accounting for at least 50% of within group 

similarity, Groups A, B, and C were each typified by a single taxon (Table 4.1). 

Stations in Groups A and B yielded the fossorial amphipods Protohaustorius wigleyi and 

Parahaustorius longimerus, respectively, while Group C stations commonly contained the 

bivalve Tellina spp. The intershoal trough stations (Group D) were characterized by the 

polychaetes Spiophanes bombyx and Asabellides oculata, the bivalve Tellina spp., and the 

tube-dwelling amphipod Unciola irrorata. Two bivalves Astarte spp. and Crenella glandula, and 

the gastropod Natica pusilla typified Station Group E. Group F stations typically yielded 

polychaetes S. bombyx and A. cerrutii and the amphipod P. wigleyi. Stations in Group G 

commonly yielded various polychaetes including Aricidea cerrutii, Aricidea catherinae, Brania 

wellfleetensis, and Aphelochaeta sp. As indicated by their lower average similarity values, 

Station Groups E, F, and G were not as well defined as Groups A through D. 
MMS Study 2010-010

41 

Figure 4.1. Approximate locations of station groups (A through G) resolved from cluster 

analysis of grab sample composition across 1998-1999 stations in the area of 

Fenwick Shoal (Original data, base map, and station locations adapted from 

Virginia Institute of Marine Science, 2000). 
MMS Study 2010-010

42 

Table 4.1. Average abundance of infaunal species accounting for at least 50% of within-group 

similarity in station (sample) Groups A through G. Numbers in bold represent 

average similarity for each group overall. 

Group Species1 Average Abundance Average Similarity 

A Protohaustorius wigleyi (A) 0.90 55.79 

55.79

B Parahaustorius longimerus (A) 1.71 23.19 

41.80

C Tellina spp. (B) 1.46 27.26 

43.48

D 

Spiophanes bombyx (P) 

Asabellides oculata (P) 

Tellina spp. (B)

Unciola irrorata (A) 

4.99 

3.40 

3.44 

2.85 

8.52 

7.37 

5.96 

5.07 

47.20

E 

Astarte spp. (B) 

Crenella glandula (B) 

Natica pusilla (G) 

1.97 

1.81 

1.14 

6.35 

6.31 

3.75 

30.93

F 

Spiophanes bombyx (P) 

Protohaustorius wigleyi (A) 

Aricidea cerrutii (P) 

1.57 

1.32 

0.92 

8.41 

5.96 

4.64 

29.39

G 

Aricidea cerrutii (P) 

Aricidea catherinae (P) 

Brania wellfleetensis (P) 

Aphelochaeta sp. (P)

2.04 

1.42 

1.57 

1.36 

6.18 

4.21 

4.18 

3.51 

35.28 

1 A = amphipod; B = bivalve; G = gastropod; P = polychaete. 

Mean number of taxa and mean individual abundance were tested for differences among the 

station groups resolved by cluster analysis. Raw data were entered into JMP—The Statistical 

Discovery Software Program for Abundance and Distribution (SAS Institute, Inc., 2007). Prior to 

analysis of variance (ANOVA) testing, the data were tested for distribution using a goodness of 

fit test to check for normality. The abundance data were determined to have a non-normality, 

and all samples were log-transformed prior to the ANOVA. Group D stations (inter-ridge 

troughs) yielded significantly greater mean individual abundance than all other station groups 

(F=16.17, p<0.0001). Mean number of taxa per station was also greater in Group D than all 

other station groups (F=18.77; p<0.0001). Further comparisons of the station group means for 

numbers of taxa were made using a student’s t-test (t=1.99; α=0.05). Station Groups A 

through C, which in general were located on or near shoal crests, had fewer taxa than Groups D 

through G (Table 4.2). 

Table 4.2. Mean number of infaunal taxa within station groups resolved by cluster analysis. 

Station Group (n) Mean Number Taxa 

A (2) 5.0 

B (4) 8.0 

C (10) 8.4 

D (10) 29.4 

E (9) 18.6 

F (10) 16.6 

G (26) 19.3 
MMS Study 2010-010

43 

During the VIMS (2000) field studies, epifauna were collected during both cruises (1998 and 

1999) with a 2.4-m beam trawl. The most abundant epifauna were hermit crabs (Pagurus spp.), 

portly spider crab (Libinia emarginata), and rock crab (Cancer irroratus). Other epifauna 

included sea stars Asterias spp. and sand dollars Echinarachnius parma, and large gastropods 

such as channeled whelk (Busycon canaliculatum) and moon snails (Polinices spp). Broadly 

distributed taxa found on and off the shoals included nudibranchs, hermit crabs, sevenspine bay 

shrimp (Crangon septemspinosa), and sea stars (VIMS, 2000). 

Slacum et al. (2006) also conducted seasonal sampling of mobile epibenthic invertebrates in the 

study area. Four shoals (Shoal B, Shoal D, Fenwick Shoal, and Weaver Shoal) and adjacent 

areas of the seafloor were sampled by trawl from fall 2002 to summer 2004. Sea stars and lady 

crabs Ovalipes spp. were the most abundant invertebrate species in the fall collections, 

accounting for 7% of the total abundance combined. Sea stars comprised 56% of the total 

invertebrate abundance on the shoals and 27% at the reference sites. Lady crabs accounted 

for 25% of invertebrates found on the shoals and 31% of invertebrates at the reference sites. 

Other benthic epifauna collected in the fall were horseshoe crab (Limulus polyphemus), 

channeled whelk, and rock crab. Highly abundant benthic invertebrates of the study area 

seafloor and shoals included right-handed hermit crabs, sea stars, lady crab, and portly spider 

crab (Slacum et al., 2006). 

4.2 FISHES 

This section examines the current state of knowledge on the structure (species composition and 

relative abundance) of fish assemblages associated with sand shoals in the Mid-Atlantic Bight. 

Information presented here is used to make inferences regarding the functional significance of 

shoals as EFH in Section 4.3. Functional significance in this context includes use of habitat for 

activities such as spawning, feeding, and sheltering as opposed to energy flow within the 

community. 

The Mid-Atlantic Bight ichthyofauna is dynamic in space and time, consisting of demersal and 

pelagic forms with boreal, warm temperate, and subtropical affinities (Grosslein and Azarovitz, 

1982; Colvocoresses and Musick, 1984; Mahon et al., 1998). At the family level, demersal 

species are represented by skates (Rajiidae), dogfishes (Squalidae), requiem sharks 

(Carcharhinidae), searobins (Triglidae), hakes (Phycidae), anglerfishes (Lophiidae), seahorses 

and pipefishes (Syngnathidae), sculpins (Cottidae), sea bass (Serranidae), drums (Sciaenidae), 

scup (Sparidae), and flatfishes (Paralichthyidae, Pleuronectidae, Scophthalmidae). 

On a broad scale, much of the spatial and temporal variations observed in Mid-Atlantic Bight 

demersal assemblages are driven by seasonal changes in water temperature. When water 

temperatures increase in the spring, warm temperate fishes move into the Mid-Atlantic Bight 

from the south; at the same time several cold water species migrate back to areas north of the 

Mid-Atlantic Bight. After shelf waters cool during fall and early winter, warm temperate species 

migrate back south and offshore while some of the cold temperate forms move into the area 

(Grosslein and Azarovitz, 1982). Typical warm temperate forms found in Mid-Atlantic Bight 

during spring and summer are black sea bass (Centropristis striata), northern searobin 

(Prionotus carolinus), scup (Stenotomus chrysops), spotted hake (Urophycis regia), and 

summer flounder (Paralichthys dentatus) (Grosslein and Azarovitz, 1982; Colvocoresses and 

Musick, 1984; Mahon et al., 1998). Northern or boreal species found in Mid-Atlantic Bight 

waters during winter and spring include goosefish (Lophius americanus), red hake (Urophycis 

chuss), offshore hake (Merluccius albidus), silver hake (Merluccius bilinearis), and yellowtail 

flounder (Limanda ferruginea) (Colvocoresses and Musick, 1984). The abundance and 
MMS Study 2010-010

44 

distribution of demersal fishes varies among seasons and years; however, the numerically 

dominant species tend to be predictable (Gabriel, 1992). In general, winter is a time of low 

abundance and diversity, as most species leave the area for warmer waters offshore and to the 

south. Some species make only local movements and may be classified as residents of the 

area, including dusky shark (Carcharhinus obscurus), lined seahorse (Hippocampus erectus), 

striped bass (Morone saxatilis), tilefish (Lopholatilus chamaeleonticeps), blackbelly rosefish 

(Helicolenus dactylopterus), summer flounder, and windowpane (Scophthalmus aquosus). 

Pelagic species found in the Mid-Atlantic Bight include sharks (Squalidae and Carcharhinidae), 

herrings (Clupeidae), anchovies (Engraulidae), mackerels (Scombridae), cobia 

(Rachycentridae), striped bass (Moronidae), bluefish (Pomatomidae), and butterfishes 

(Stromateidae). All of these species form schools of varying sizes and migrate seasonally. As 

with the demersal fishes, most pelagic species found in the Mid-Atlantic Bight are transitory, 

originating in waters either to the north (Gulf of Maine or Georges Bank) or to the south (south 

of Cape Hatteras). Their occurrence in the Mid-Atlantic Bight is generally a response to 

seasonal changes in water temperature, which trigger southerly or northerly movements by 

species of southern or northern origin, respectively. 

In concert with seasonal water temperature changes, most large-scale migrations of pelagic 

fishes in the Mid-Atlantic Bight are related to spawning. General patterns include 1) cross-shelf 

movements to offshore spawning areas; 2) movements along the shelf to southerly spawning 

areas; and 3) movements between coastal rivers and the coastal ocean for spawning or the 

reverse (diadromy). Movement of butterfish (Peprilus triacanthus) exemplifies the first pattern. 

The population migrates northward and inshore in summer then during winter months moves 

southward and offshore. During this time, butterfish spawn continuously from late January to at 

least July in the Mid-Atlantic Bight (Rotunno and Cowen, 1997). Bluefish (Pomatomus saltatrix), 

Atlantic mackerel (Scomber scombrus), Atlantic menhaden (Brevoortia tyrannus), and Atlantic 

herring (Clupea harengus) migrate following the second general pattern by moving along the 

coast to preferred spawning areas. For the diadromous pattern, alewife 

(Alosa pseudoharengus), blueback herring (Alosa aestivalis), American shad (Alosa 

sapidissima), and striped bass are anadromous, ascending from the ocean up coastal rivers to 

spawn in freshwater, whereas the catadromous American eel (Anguilla rostrata) descends 

coastal rivers into the ocean to spawn. 

4.2.1 Fishes and Life Stages Associated with Sand Shoals 

Fish assemblages associated with shoals in the Mid-Atlantic Bight region are composed of 

varying subsets of the regional ichthyofauna. Studies focusing strictly on fishes associated with 

sand shoals in the Mid-Atlantic Bight have been conducted in only two areas of the continental 

shelf, one off Maryland/Delaware and one off New Jersey (Figure 1.5). The New Jersey site 

consists of a single large shoal feature known as Beach Haven Ridge located ~11 km offshore 

of Little Egg Inlet in water depths of 2 to 19 m (Figure 1.5). This site was studied intensively 

from 1972 to 1975 when it was the candidate site for the proposed Atlantic electric power 

generating plant (Milstein and Thomas, 1977). During that period, Beach Haven Ridge was 

sampled for fishes by otter trawling monthly or biweekly. In addition, from 1973 to 1975, fish 

eggs and larvae were collected around the shoal using plankton nets. Data gathered during 

these field surveys were initially reported by Milstein and Thomas (1977) and later summarized 

by Able and Hagan (1995). During the 1990’s, researchers from the Rutgers University Institute 

of Marine and Coastal Sciences, Marine Field Station in Tuckerton, New Jersey began 

gathering data on individual species (Lazzari and Able, 1990; McBride and Able, 1994; Able et 

al., 1995; Morse and Able, 1995; Campbell and Able, 1998; Duval and Able, 1998; Hales and 
MMS Study 2010-010

45 

Able, 2001) as well as whole assemblages (Martino and Able, 2003: Able et al., 2006; Vasslides 

and Able, 2008) along a cross-shelf transect that extends from inside Little Egg Inlet out across 

Beach Haven Ridge. The data collected here are of particular value in determining habitat use 

because Beach Haven Ridge was located within a broader habitat gradient that extends from 

inshore (inside Great Bay) to the middle continental shelf. Understanding the importance of 

shoals as EFH will depend on the extent to which they connect with other habitats along the 

larger cross-shelf continuum. 

The second location where fish utilization of shoals has been studied is offshore Maryland and 

Delaware (Figure 4.2). Specific shoals in the area including Fenwick Island Shoal, Weaver 

Shoal, Shoal B, and Shoal D were sampled by Cutter et al. (2000), Diaz et al. (2003), and 

Slacum et al. (2006). Rather than sampling long transects that traversed these shoals, as was 

the case with Beach Haven Ridge, these studies sampled across individual shoal areas using a 

variety of gear types including large (commercial) trawl, small otter trawl, beam trawl, gill net, 

towed video, and hydroacoustic imaging. Different techniques sample different components of 

the assemblage, and are in many respects, complementary. Slacum et al. (2006) executed a 

sampling design that included pairs of shoal and nonshoal reference sites to examine 

hypotheses regarding the use of shoals by fishes. Although systematic sampling along a 

cross-shelf gradient was not formally conducted at the Maryland-Delaware location, 

considerable information concerning inshore habitat use is available from the adjacent Delaware 

Bay Estuary (see review by Able et al., 2007). 

The data and information from the study of these two shoal areas are reviewed with a focus on 

species and life stage composition. Literature and data for other habitats composing the 

cross-shelf continuum are also considered, including the lower estuarine environment and the 

middle and outer shelf. This allows shoals to be placed into the context of cross-shelf 

continuum of habitats, for purposes of management and EFH identification, an understanding of 

connections among various demersal and pelagic habitats is vital. In the following section, 

species composition is characterized by life stage based on available data. 

4.2.2 Eggs and Larvae 

Able and Hagan (1995) reported the densities and seasonality of eggs and larvae collected 

during the 1970’s, and Able et al. (2006) reported larvae but not eggs collected in the same area 

during the 1990’s. Eggs of 10 demersal taxa were collected at Beach Haven Ridge including 

cod (Gadus morhua), red hake, searobins (Prionotus spp.), windowpane, and sand lance 

(Ammodytes sp.) (Table 4.3). Of these taxa, Able and Hagan (1995) reported average number 

of eggs per 1,000 m3

 were highest for searobins (356), windowpane (341), and tautog (Tautoga 

onitis) (122). Eggs of all other demersal taxa averaged 20 or fewer per 1,000 m3

. Eggs of bay 

anchovy (Anchoa mitchilli), striped anchovy (Anchoa hepsetus), Atlantic mackerel, and Atlantic 

menhaden represented the pelagic group (Table 4.4). Bay anchovy (6,681 eggs per 1,000 m3

) 

and Atlantic mackerel (1,411 eggs per 1,000 m3

) contributed the highest average numbers of 

eggs at Beach Haven Ridge during the 1970’s (Able and Hagan, 1995). It should be noted that 

the order in which fishes are listed in Tables 4.3 to 4.6 appears according to ranking based on 

occurrence across studies. 
MMS Study 2010-010

46 

Figure 4.2. Overview of shoal sample areas. 
MMS Study 2010-010

47 

Table 4.3. Eggs and larvae of demersal fish taxa collected in the vicinity of Beach Haven Ridge 

sand shoal offshore New Jersey during 1972 to 1975 and 1992 to 1995 (From: Able 

and Hagan, 1995; Able et al., 2006). 

Scientific Name Common Name Eggs 

(1972-1975)

Larvae 

(1972-1975) 

Larvae 

(1992) 

Urophycis regia Spotted hake + + + 

Tautoga onitis Tautog + + + 

Tautolabrus adspersus Cunner + + + 

Scophthalmus aquosus Windowpane + + + 

Urophycis chuss Red hake + + 

Syngnathus fuscus Dusky pipefish + + 

Centropristis striata Black sea bass + + 

Cynoscion regalis Weakfish + + 

Micropogonias undulatus Atlantic croaker + + 

Etropus microstomus Smallmouth flounder + + 

Urophycis sp. Hake + + 

Lophius americanus Goosefish + + 

Prionotus spp. Searobin + + 

Ammodytes sp. Sand lance + + 

Pollachius virens Pollack + 

Ophidiidae Cusk eel + 

Hippocampus erectus Lined seahorse + 

Prionotus carolinus Northern searobin + 

Menticirrhus saxatilis Northern kingfish + 

Astroscopus sp. Stargazer + 

Gobiosoma ginsburgi Seaboard goby + 

Gobiosoma bosc Naked goby + 

Gobiidae Goby + 

Lumpenus lampretaeformis Snakeblenny + 

Paralichthys dentatus Summer flounder + 

Paralichthys oblongus Fourspot flounder + 

Pholis gunnellus Rock gunnel + 

Pseudopleuronectes americanus Winter flounder + 

Trinectes maculatus Hogchoker + 

Tetraodontiformes Puffer + 

Gadus morhua Cod + 

Enchelyopus cimbrius Fourbeard rockling + 

Limanda ferruginea Yellowtail flounder + 

Gadidae Cod + 

Myoxocephalus sp. Sculpin + 

Myoxocephalus octodecemspinosus Fourhorn sculpin + 

Sciaenidae Drum + 

Abudefduf saxatilis Sergeant major + 

Citharichthys sp. Whiff + 

Glyptocephalus cynoglossus Witch flounder + 

Total 10 34 14 
MMS Study 2010-010

48 

Table 4.4. Eggs and larvae of pelagic fish taxa collected in the vicinity of Beach Haven Ridge 

sand shoal offshore New Jersey during 1972 to 1975 and 1992 to 1995 (From: Able 

and Hagan, 1995; Able et al., 2006). 

Scientific Name Common Name Eggs 

(1972-1975) 

Larvae 

(1972-1975) 

Larvae 

(1992) 

Brevoortia tyrannus Atlantic menhaden + + + 

Anchoa hepsetus Striped anchovy + + 

Anchoa mitchilli Bay anchovy + + + 

Engraulidae Anchovy + 

Atherinidae Silversides +

Pomatomus saltatrix Bluefish + 

Scomber scombrus Atlantic mackerel + 

Scomberomorus cavalla King mackerel + 

Peprilus triacanthus Butterfish + 

Total 4 8 2 

Table 4.5. Adult and juvenile demersal fishes collected around sand shoals offshore New 

Jersey, Delaware, and Maryland (Sources: Able and Hagan, 1995; Martino and 

Able, 2003; Able et al., 2006; Slacum et al., 2006; Vasslides and Able, 2008). 

Scientific Name Common Name 

Beach Haven Ridge, NJ 

(1972-1975) 

Beach Haven Ridge, NJ 

(1992) 

Beach Haven Ridge, NJ 

(1997-1999) 

Fenwick Island Shoal 

Weaver Shoal 

Shoal B 

Shoal D 

Leucoraja erinacea Little skate + + + + + + + 

Raja eglanteria Clearnose skate + + + + + + + 

Urophycis regia Spotted hake + + + + + + + 

Prionotus carolinus Northern searobin + + + + + + + 

Stenotomus chrysops Scup + + + + + + + 

Scophthalmus aquosus Windowpane + + + + + + + 

Etropus microstomus Smallmouth flounder + + + + + + + 

Paralichthys dentatus Summer flounder + + + + + + + 

Leucoraja ocellata Winter skate + + + + + + 

Prionotus evolans Striped searobin + + + + + + 

Micropogonias undulatus Atlantic croaker + + + + + + 

Synodus foetens Inshore lizardfish + + + + + 

Dipturus laevis Barndoor skate + + + + 

Myliobatis freminvillei Bullnose ray + + + + 

Merluccius bilinearis Silver hake + + + + 

Hippocampus erectus Lined seahorse + + + + 

Cynoscion regalis Weakfish + + + + 

Ammodytes americanus American sand lance + + + + 

Urophycis tenuis White hake + + + 

Ophidion marginatum Striped cusk eel + + + 

Syngnathus fuscus Dusky pipefish + + + 

Bairdiella chrysoura Silver perch + + + 
MMS Study 2010-010

Table 4.5. (Continued). 

49 

Scientific Name Common Name 

Beach Haven Ridge, NJ 

(1972-1975) 

Beach Haven Ridge, NJ 

(1992) 

Beach Haven Ridge, NJ 

(1997-1999) 

Fenwick Island Shoal 

Weaver Shoal 

Shoal B 

Shoal D 

Pseudopleuronectes americanus Winter flounder + + + 

Gymnura micrura Smooth butterfly ray + + 

Lophius americanus Goosefish + + 

Centropristis striata Black sea bass + + 

Leiostomus xanthurus Spot + + 

Menticirrhus saxatilis Northern kingfish + + 

Astroscopus guttatus Northern stargazer + + 

Gobiosoma ginsburgi Seaboard goby + + 

Limanda ferruginea Yellowtail flounder + + 

Sphoeroides maculatus Northern puffer + + 

Squatina dumeril Atlantic angel shark + 

Dasyatis centroura Roughtail stingray + 

Dasyatis say Bluntnose stingray + 

Gymnura altavela Spiny butterfly ray + 

Rhinoptera bonasus Cownose ray + 

Acipenser oxyrhynchus Atlantic sturgeon + 

Conger oceanicus Conger eel + 

Trachinocephalus myops Snakefish + 

Melanogrammus aeglefinus Haddock + 

Urophycis chuss Red hake + 

Enchelyopus cimbrius Fourbeard rockling + 

Opsanus tau Oyster toadfish + 

Apeltes quadracus Fourspine stickleback + 

Gasterosteus aculeatus Threespine stickleback + 

Fistularia tabacaria Bluespotted cornetfish + 

Hemitripterus americanus Sea raven + 

Myoxocephalus aenaeus Grubby + 

Liparis inquilinus Inquiline snailfish + 

Mycteroperca microlepis Gag + 

Pristigenys alta Short bigeye + 

Larimus fasciatus Banded drum + 

Pogonias cromis Black drum + 

Pseudupeneus maculatus Spotted goatfish + 

Tautoga onitis Tautog + 

Zoarces americanus Ocean pout + 

Hypsoblennius hentz Feather blenny + 

Gobiosoma bosc Naked goby + 

Citharichthys spilopterus Bay whiff + 

Paralichthys oblongus Fourspot flounder + 

Trinectes maculatus Hogchoker + 

Monacanthus hispidus Planehead filefish + 

Chilomycterus schoepfii Striped burrfish + 

Total 50 23 25 24 22 13 11 
MMS Study 2010-010

50 

Table 4.6. Adult and juvenile pelagic fishes collected around sand shoals offshore New Jersey, 

Delaware, and Maryland (From: Able and Hagan, 1995; Martino and Able, 2003; 

Able et al., 2006; Slacum et al., 2006; Vasslides and Able, 2008). 

Scientific Name Common Name 

Beach Haven Ridge, NJ 

(1972-1975) 

Beach Haven Ridge, NJ 

(1992) 

Beach Haven Ridge, NJ 

(1997) 

Fenwick Island Shoal 

Weaver Shoal 

Shoal B 

Shoal D 

Squalus acanthias Spiny dogfish + + + + + + 

Mustelus canis Smooth dogfish + + + + + + 

Pomatomus saltatrix Bluefish + + + + + + 

Peprilus triacanthus Butterfish + + + + + + 

Rhizoprionodon terraenovae Atlantic sharpnose shark + + + + + 

Alosa pseudoharengus Alewife + + + + 

Alosa sapidissima American shad + + + + 

Brevoortia tyrannus Atlantic menhaden + + + + 

Menidia menidia Atlantic silverside + + + + 

Morone saxatilis Striped bass + + + + 

Caranx crysos Blue runner + + + + 

Scomberomorus maculatus Spanish mackerel + + + + 

Carcharhinus plumbeus Sandbar shark + + + 

Clupea harengus Atlantic herring + + + 

Anchoa hepsetus Striped anchovy + + + 

Anchoa mitchilli Bay anchovy + + + 

Alopias vulpinus Thresher shark + + 

Alosa aestivalis Blueback herring + + 

Rachycentron canadum Cobia + + 

Decapterus punctatus Round scad + + 

Sarda sarda Atlantic bonito + + 

Scomber scombrus Atlantic mackerel + + 

Carcharhinus obscurus Dusky shark + 

Alosa mediocris Hickory shad + 

Etrumeus teres Round herring + 

Engraulis eurystole Silver anchovy + 

Morone americana White bass + 

Seriola zonata Banded rudderfish + 

Sphyraena borealis Northern sennet + 

Peprilus alepidotus Harvestfish + 

Total 12 21 8 13 13 10 11 
MMS Study 2009-XXX

51 

The larvae of 34 demersal taxa occurred in plankton net samples over a 3-year period from 

Beach Haven Ridge in 1970’s (Table 4.3). Sand lance numerically dominated the catches, 

averaging 1,008 larvae per 1,000 m3

, followed by gobies (43 larvae per 1,000 m3) and searobins 

(Prionotus) (16 larvae per 1,000 m3

) (Able and Hagan, 1995). During the 1990’s, Able et al. 

(2006) collected 14 larvae of demersal taxa including 10 previously reported by Able and Hagan 

(1995). These included larvae of spotted hake, tautog, cunner (Tautolabrus adspersus), black 

sea bass, seaboard goby (Gobiosoma ginsburgi), Atlantic croaker (Micropogonias undulatus), 

windowpane, searobins (Prionotus), and red hake from around Beach Haven Ridge (Table 4.3). 

The most abundant taxa collected in the 1990’s were windowpane (7.9 larvae per 1,000 m3

), 

smallmouth flounder (Etropus microstomus) (7.8 larvae per 1,000 m3

), weakfish (Cynoscion 

regalis) (4.9 larvae per 1,000 m3

), and dusky pipefish (Syngnathus fuscus) (3.5 larvae per 

1,000 m3

). Most of the early (preflexion) larvae collected by Able et al. (2006) were taken in 

coastal ocean waters, not in the estuary. 

Larvae of eight pelagic taxa were collected during the 1970’s near Beach Haven Ridge (Able 

and Hagan, 1995) (Table 4.4). Averaging 847 larvae per 1,000 m3

, anchovies were by far the 

most abundantly collected larval taxon (Able and Hagan, 1995). During the 1990’s sampling, 

only two taxa were reported as larvae (Table 4.4): bay anchovy (66.2 larvae per 1,000 m3

), 

unidentified anchovies (359.8 per 1,000 m3

), and Atlantic menhaden (13.2 larvae per 1,000 m3) 

(Able et al., 2006). 

4.2.3 Juveniles and Adults 

Juvenile and adult stage species are treated together in this subsection because researchers 

did not always distinguish the two in their data reports. The combined studies reported 

64 demersal species from 36 families. The most species rich families were skates, hakes, 

drums, and sand flounders. Eight species were collected during all studies from five shoal 

areas (Table 4.5). These were little skate (Leucoraja erinacea), clearnose skate (Raja 

eglanteria), spotted hake, northern searobin, scup, windowpane, smallmouth flounder, and 

summer flounder. 

The Beach Haven Ridge trawl sampling from 1972 to 1975 produced 50 demersal species (Able 

and Hagan, 1995) (Table 4.5). During unseasonably warm periods, a number of species 

originating with more subtropical affinities, including bluespotted cornetfish (Fistularia tabacaria), 

short bigeye (Pristigenys alta), gag (Mycteroperca microlepis), round scad (Decapterus 

punctatus), goatfish (Mullidae), and gray snapper (Lutjanus griseus), were collected (Milstein 

and Thomas, 1976). Many of these tropical and subtropical species do not survive following the 

onset of low winter temperatures (e.g., McBride and Able, 1998), but there is evidence that 

some warm temperate species are expanding their range into the Mid-Atlantic Bight in response 

to climate change (Hare and Able, 2007). 

During the 1990’s, the most common juvenile and adult fishes collected at Beach Haven Ridge 

(Martino and Able, 2003; Vasslides and Able, 2008) were searobins, gobies, black sea bass, 

and drums. Most of the juveniles reported by Able et al. (2006) were found in both estuarine 

and coastal ocean waters. The sampling distinguished species that were seasonal from those 

that were year-round residents. Seasonal species included boreal (cold temperate) forms only 

present during winter and spring, including herrings, hakes, sticklebacks, and sculpins. Species 

collected year-round were silver hake, spotted hake, smallmouth flounder, and windowpane. 

The shoals off Maryland and Delaware were sampled during spring, summer, fall, and winter for 

2 years using trawls (small and large), gill nets, and hydroacoustics (Slacum et al., 2006). 
MMS Study 2010-010

52 

A total of 57 species was collected from all sampling sites including shoals and nonshoal 

reference sites (Slacum et al., 2006). Fenwick Island Shoal supported the most species 

followed by Weaver Shoal. The average number of individuals collected by trawl varied with the 

size of the gear and season. Catch per unit effort on the shoals by the smaller trawl ranged 

from 0.52 on Shoal D to 129.4 on Weaver Shoal. Average catches by the larger commercial 

trawl ranged from 10.97 at Shoal D to 1,577 individuals at Weaver Shoal. Catches were highest 

during the spring sampling period. Winter skate (Leucoraja ocellata), scup, and windowpane 

were the most abundant species collected overall by the larger trawl. In general, the lowest 

catches were made during winter and highest in fall and spring. Although much of the statistical 

analyses of the net data indicated no significant difference between shoals and nonshoal 

reference areas, individual samples demonstrated considerable variability. For example, 

1,225 (catch per unit of effort 583.49) striped bass were collected in one tow of the large at 

Fenwick Island Shoal during fall of 2003, and 3,336.74 (catch per unit effort) scup were 

collected by large trawl a Fenwick Shoal during spring of 2004. 

Slacum et al. (2006) deployed gill nets to sample the water column for pelagic species. 

Twenty-one fish species were collected by gill net across the shoals. Smooth (Mustelus canis) 

and spiny (Squalus acanthias) dogfish were the most abundant species collected. Gill net 

catches ranged from 0 fish at Shoal B, Shoal D, and Weaver Shoal to 46.74 individuals at 

Shoal B and were highest during summer sampling periods. 

Pelagic fishes collected around the Maryland-Delaware shoals (Table 4.6) included herrings 

such as alewife, American shad, blueback herring, Atlantic herring, and Atlantic menhaden; 

mackerels including Spanish mackerel (Scomberomorus maculatus) and Atlantic mackerel; 

bluefish; cobia (Rachycentron canadum); and butterfish. Coastal sharks were represented by 

spiny dogfish, Atlantic sharpnose shark (Rhizoprionodon terraenovae), dusky shark, and 

sandbar shark (Carcharhinus plumbeus) (Slacum et al., 2006). Milstein (1981) reported the size 

and abundance of juvenile herrings (Alosa spp.) in the vicinity of Beach Haven Ridge. 

Slacum et al. (2006) also employed hydroacoustic echosounding technology to estimate total 

biomass and abundance of pelagic and demersal fishes associated with the shoals. This 

approach is effective in mapping distributions of fish schools (or single larger individuals) over a 

spatial grid surveyed with a hydroacoustic transducer and will sample fishes that normally avoid 

conventional bottom trawl gear. Sampling conducted at night found aggregations of fishes were 

present during nighttime hours but not as much during the day. 

In summary, a diverse array of species and their life stages have been collected and 

documented in association with sand shoals in two areas of the Mid-Atlantic Bight continental 

shelf. There are several demersal and pelagic species that affiliate with shoals as well as other 

habitats along the cross-shelf continuum. From egg and larval data, it appears that several 

species spawn in the vicinity of shoals. Juvenile and adult occurrences also indicate that shoals 

provide habitat for several species. It is likely that these species are seeking food, shelter, 

orientation, or a break from the currents when they associate with sand shoals. Presence, 

abundance, and species richness are partial indicators of habitat quality; however, additional 

information on species-specific growth rates, reproductive output, feeding habits, and 

movements is needed to provide adequate assessments of habitat quality. 
MMS Study 2009-XXX

53 

4.3 INTERACTIONS BETWEEN INVERTEBRATES AND FISHES 

4.3.1 Trophic Relationships 

Regardless of the level of complexity, most marine food webs share fundamental structural and 

ordering characteristics with those of estuarine, fresh water, and terrestrial systems (Dunne 

et al., 2004). Dredging removes benthic invertebrates along with sediments, and therefore 

pathways of trophic energy flow and reproductive potential are removed from mined sites until 

after recolonization occurs. Link (2002) suggested that marine food webs are complex due to 

their openness, lack of specialists, long lifespans, and large size changes across the life 

histories of many species. Reise (2002), however, suggested that benthic communities in 

marine sediments have a simple trophic structure in general, but in combination with 

bioengineering and bioturbation these phenomena result in a complex “habitat web.” 

Benthic invertebrates have an important role in transferring energy from organic detritus to 

higher trophic levels (Newell et al., 1998) and invertivory is the primary trophic feature of most 

benthic and many pelagic fishes. The study area is similar to inner shelf systems, with generally 

coarse sediments and a low standing stock of organic carbon. The ultimate source of organic 

detritus in oceanic surface waters is biological production (Suess, 1980). Deposition of 

particulate organic matter is subject to seasonal variations caused by the phytoplankton annual 

productivity cycle (Graff, 1992), and detrital inputs are important for provision of organic matter 

to the benthos (Levinton and Kelaher, 2004). Detritus may increase system stability and 

persistence through substantial effects on trophic structure and biodiversity (Moore et al., 2004). 

There are strong correlations between primary production and the standing crop and production 

of benthic macrofauna in phytoplankton-dominated marine ecosystems (Nixon and Buckley, 

2002). Low amounts of organic enrichment may limit secondary production in open shelf 

sediments (Day et al., 1971; Hanson et al., 1979; Tenore, 1985). Howe et al. (1988) estimated 

secondary production of benthic mollusks at a Delaware Bay site and two coastal Delaware 

sites and found decreasing production from the estuary to the inner shelf, with total mollusk 

production markedly lower at an offshore station compared to inshore locations. 

In the western North Atlantic, bivalves contribute the greatest percentage of total infaunal 

biomass, accounting for between 58% and 65% of biomass in depths less than 100 m (Wigley 

and Theroux, 1981). Bivalves were the major contributors to biomass during the 1998 to 

1999 cruises in the study area (VIMS, 2000), with 8 taxa in the top 24 for total biomass. Wet 

weight biomass was dominated by surf clams (Spisula solidissima), which represented 65% of 

the total biomass for both cruises. After bivalves, the primary contributors to study area 

biomass include several polychaetes and amphipods. High biomass polychaetes are 

predominantly associated with intershoal swales, such as those on the lee (south) side of 

Weaver Shoal. Amphipods are more widespread, with mostly tube-dwellers associated with 

swales and burrowing amphipods on the shoals. Overall, swales and troughs tend to have 

greater benthic macrofaunal density and biomass compared with areas without depressions 

(Boesch, 1979; Barros et al., 2004). 

In addition to surf clams and burrowing amphipods, common macrobenthos inhabiting potential 

mining sites of the study area include tunicates, sand dollars, mussels, and other 

suspension-feeding benthos, as well as various annelids. Many of these benthic invertebrates 

are prey for motile epifauna and demersal fishes. Juvenile surf clams are consumed by 

common shoal taxa such as moon snails, spider crabs (Lilbinia spp.), rock crabs (Cancer spp.), 

lady crabs (Ovalipes ocellatus) (Franz, 1977; Fay et al., 1983; Dietl and Alexander, 1997), and 
MMS Study 2010-010

54 

sea stars (Meyer et al., 1981). Larger clams are less commonly consumed due to their thicker 

shells. Fish predators of surf clams typically consume smaller clams (Ropes, 1980). 

There is relatively little information on direct fish feeding on shoal invertebrates, though basic 

patterns may be inferred from related information (e.g., Able and Fahay, 1998). Weaver Shoal 

can undergo substantial diel shifts in pelagic fish fauna, whereas some smaller shoals may not 

(Slacum et al., 2006). These day-night shifts in ichthyofaunal assemblages may be associated 

in part with feeding, but mechanisms are unstudied. 

Bottom-dwelling decapods are among the chief consumers of the benthos, and in general are 

opportunistic predators. Rock crabs and lady crabs feed on the most commonly abundant 

invertebrates of coastal sediments, including polychaetes, bivalves, echinoderms, and smaller 

crustaceans (Stehlik, 1993). Blue crabs (Callinectes sapidus) are also opportunistic feeders, 

and consume locally abundant infauna, epifauna, and fish (Tagatz, 1968). Sevenspine bay 

shrimp (Crangon septemspinosa) feed on mollusks, arthropods, annelids, and fish (Wilcox and 

Jeffries, 1974; Witting and Able, 1993; Bertram and Leggett, 1994). 

Some larval and juvenile fishes are vulnerable to decapod predation. For example, larval and 

recently settled winter flounder (Bertram and Leggett, 1994; Witting and Able, 1995) and 

summer flounder (Witting and Able, 1993) may suffer significant levels of mortality due to 

predation by sevenspine bay shrimp. Typically, there is also substantial predation upon 

crustaceans by older life stages of fishes such as summer flounder (Able and Kaiser, 1994). 

Common decapods of the study area are a primary component of the diets of demersal fishes. 

In the Mid-Atlantic Bight, sevenspine bay shrimp, portunid crabs (lady crab and blue crab), and 

rock crabs are important prey for fishes (Bowman et al., 2000). Decapods and amphipod 

crustaceans were the most common food items identified in the stomachs of fishes collected in 

the study area (VIMS, 2000). Lady crabs are an important component in the diet of fishes such 

as cobia (Arendt et al., 2001). 

Because decapods are opportunistic predators of infauna, and in turn are important in the diet of 

higher predators, they may provide an important link between benthic secondary production and 

higher trophic levels on the inner shelf. Sevenspine bay shrimp is a numerically dominant 

species inhabiting coastal and estuarine waters (Heck and Thoman, 1984), and is known to play 

an important role in food energy transfer in tidal marsh estuarine ecosystems (Haefner, 1979). 

Similarly, blue crabs play a major role in energy transfer within estuaries (Baird and Ulanowicz, 

1989). Bay shrimp, blue crabs, and other highly motile decapods of the study area may serve a 

similar role in shoal systems. 

4.3.2 Habitat Engineers 

Physical ecosystem engineering (habitat engineers) by organisms is the physical modification, 

maintenance, or creation of habitats (Jones et al., 1994, 1997). Ecological effects of habitat 

engineering occur because the physical state changes directly or indirectly control resources 

used by other species. According to Reise (2002), bioengineered structures and engineering 

processes generate dynamic and complex habitat-mediated interaction webs, affecting and 

meshed into the trophic web, which they may rival in overall importance in the self-structuring of 

the benthos. Reise (2002) further suggested that in near-shore sediments, biogenic habitat 

transformations pervade all community interactions. 
MMS Study 2009-XXX

55 

Organisms that provide structural complexity are generally found to enrich local biodiversity 

compared to nonstructured habitat (Heck and Wetstone, 1977; Summerson and Peterson, 

1984; Thompson et al., 1996; Tolley and Volety, 2005; Cocito, 2006; Eriksson et al., 2006; 

Borthagaray and Carranza, 2007; Voultsiadou et al., 2007; Van Hoey et al., 2008) and may also 

increase biomass production (Tolley and Volety, 2005; Eriksson et al., 2006). The structure of 

spatially complex habitats may mitigate predator-prey interactions by providing places for prey 

to hide or escape predators, though attracting and concentrating predators in some cases may 

negate refuge value in some circumstances (Grabowski and Powers, 2004). 

In shallow subtidal sediments, community structure is determined largely by disturbances and 

physical stresses (Probert, 1984; Hall, 1994; Thrush et al., 1996). Patchiness in the distribution 

of marine sedimentary habitats may be important in maintaining community patterns of diversity, 

and the spatial distribution and size of habitats in an open shelf landscape play an important 

role in the functioning and structure of benthic communities (Thorson, 1957; Abele and Walters, 

1979; Andrew and Mapstone, 1987; Morrisey et al., 1992; Hall et al., 1994; Zajac et al., 1998, 

2003; Pineda, 2000; Thrush et al., 2000, 2005; Levinton and Kelaher, 2004). Bioengineered 

structures create variation in resources in otherwise featureless substrata, and thereby influence 

the distribution of associated species (Jones et al., 1994, 1997). 

Small resident species of juvenile fishes and motile epifauna are often found in high 

abundances in biogenic habitats (Summerson and Peterson, 1984). Intershoal swales and 

other areas to the southwest and southeast of Weaver Shoal support tube-building polychaetes 

(Asabellides and Diopatra) and other surface-oriented infauna and epifauna (VIMS, 2000). 

Compared to higher areas on the shoals, small crabs are most abundant in these habitats with 

biogenic structure (Diaz et al., 2003). Polychaete tube mats are important sources of 

microhabitat structure and supported two to four times more fishes (Diaz et al., 2003). On 

Fenwick and Weaver Shoals, the incidence of fishes was four times higher in areas with large 

bedforms (sand waves >30 cm wavelength and approximately 10 cm crest height) (Diaz et al., 

2003). 

4.3.3 Bioturbation 

Bioturbation is the displacement and mixing of sediment particles by benthic fauna. Faunal 

activities, such as burrowing, ingestion and defecation of sediment grains, construction and 

maintenance of galleries, infilling of abandoned dwellings, and feeding, displace sediment 

grains and mix the sediment matrix (Hall, 1994). Pearson (2001) noted that bioturbation may in 

fact be more important than physical forces in particle recycling and mixing detritus within the 

sediment matrix. 

Biological disturbances rework sediments, causing changes to habitat properties such as 

sediment stability and permeability, and influencing community patterns (Jones and Jago, 1993; 

Thrush et al., 1996). Foraging by predators may also mix and displace sediments (Woodin, 

1981; Oliver and Slattery, 1985; Hall et al., 1991). The sediment-water interface increases in 

area as a result of bioturbation, affecting chemical fluxes and exchange between the sediment 

and water column. Some organisms may further enhance chemical exchange by flushing their 

burrows with the overlying waters, a process termed bio-irrigation. 
MMS Study 2010-010

56 

Burrowing and irrigation activity of infauna can distribute oxygen much deeper into the sediment 

(Rhoads et al., 1977). Bioturbation will to some degree promote benthic recovery after 

dredging. Sediment surfaces exposed by dredging typically are oxygen poor, and in addition to 

pore water flushing due to boundary shear flow, the activities of fauna such as burrowing 

nereidid polychaetes (Kristensen et al., 1985) and subsurface irrigating fauna (Forster and Graf, 

1995) help improve habitat quality. 

4.4 RECOLONIZATION 

4.4.1 Settlement Patterns 

Active selection of a settling site is common in invertebrate larvae, which respond to physical 

and chemical indicators of habitat suitability (Butman et al., 1988; Pawlik, 1992; Tamburri et al., 

1996; Abelson and Denny, 1997; Snelgrove et al., 2001; Ullberg and Ólafsson, 2004; Duchêne, 

2004). Larvae may use a complex suite of chemical and sedimentological cues when making a 

decision to accept or reject a settlement site (Eckman, 1996; Qian, 1999), including factors such 

as sediment grain size, presence of adults, and organic content. For both fishes and 

invertebrates, habitats must have some minimal suitability appropriate to metamorphosing 

stages to trigger settlement (Thorson, 1957; Butman, 1987; Able and Fahay, 1998; Sullivan 

et al., 2000). 

Since marine larvae are generally weak swimmers (Mileikovsky, 1973; Chia et al., 1984), 

large-scale transport of larvae is due to passive motion under most prevailing turbulent flow 

conditions (Butman, 1987; Shanks, 1995; Abelson and Denny, 1997). Turbulent processes and 

tidal fronts concentrate and entrain pelagic larvae (Clancy and Epifanio, 1988; Hongguang and 

Grassle, 2004). Delivery of pelagic larvae to particular locations across large areas of the open 

shelf may depend particularly on hydrographic forces that transport larval patches present in the 

water column. The primary agents of larval transport in the Mid-Atlantic Bight include 

alongshore wind stress and density differences between water masses (Hare and Cowen, 1996; 

Epifanio and Garvine, 2001). In the Weaver Shoal study area, this interaction results in a set of 

buoyancy-driven currents that flow southward in a narrow band along to the coast, and 

strongest just south of major estuaries (Garvine, 1987; Epifanio and Garvine, 2001). As river 

discharge from the Delaware estuary diminishes in the late summer, the effect of winds (relative 

to buoyancy forcing) on larval transport may increase (Natunewicz et al., 2001). 

Over smaller spatial scales, bottom shear slows hydrodynamic flow, increasing the importance 

of maneuverability, the ability to detect settlement cues, and settlement itself (Scheltema, 1986; 

Butman, 1987; Eckman, 1996; Abelson and Denny, 1997; Qian, 1999; Pineda, 2000). 

Exploratory larval behavior is more important over small spatial and temporal scales 

immediately preceding or during initial contact with the substratum. Changes in benthic 

boundary layer flow have potential to alter small-scale patterns of larval behavior and settlement 

(Scheltema, 1986; Butman, 1987; Eckman et al., 1990; Jonsson et al., 1991; Gross et al., 1992; 

Snelgrove, 1994; Snelgrove and Butman, 1994; Abelson and Denny, 1997; Snelgrove et al., 

1998; Crimaldi et al., 2002; Lindegarth et al., 2002). Settlement cues that initiate termination of 

planktonic life must operate under the hydrodynamic conditions experienced by a larva while in 

the bottom boundary layer (Scheltema, 1986; Eckman, 1996). 
MMS Study 2009-XXX

57 

Though benthic larvae respond to specific habitat cues, the availability and abundance of larvae 

may sometimes be more important than habitat characteristics in determining patterns of 

settlement (Snelgrove et al., 2001). However, the relationship between larval availability, 

dispersal, and recruitment is complex, and settlement and recruitment may not correlate directly 

with larval supply (Bhaud, 1998; Pineda, 2000). Moreover, rather than larval supply or 

settlement rates, post-settlement migration, differential vulnerability to predation, and other 

ecological processes may have strong controlling influences on adult distributions and 

community patterns (Ólafsson et al., 1994; Gosselin and Qian, 1997; Bhaud, 1998; Palma et al., 

1999). The relative importance of temporal and spatial variability in larval abundance, 

settlement, and early survival in controlling observed patterns in adult populations is likely to 

vary among locations, times, habitat types, and species (Butman, 1987; Ólafsson et al., 1994). 

4.4.2 Recovery Dynamics 

The benthic community often recovers rapidly in offshore dredged sites (Johnson and Nelson, 

1985; Jutte et al., 2002; Posey and Alphin, 2002) but this depends in part on a wide array of 

criteria for what recovery is and how to measure it (Wilbur and Stern, 1992; Nelson, 1993). 

Inner shelf sediments support fauna that are adapted to periodic disturbance (Day et al., 1971; 

Pratt, 1973). Faunal recovery in disturbed sediments is most rapid in less physically stable 

habitats (Collie et al., 2000). Resiliency of invertebrate assemblages in marine subtidal 

sediments is due primarily to the opportunistic life histories and behaviors inherent in many 

benthic populations (Newell et al., 1998; Posey and Alphin, 2002). 

There may be short-term physical effects of dredging related to degraded hydrology in 

excavated sites. Anoxic, hypoxic, or noxious conditions may inhibit faunal colonization of 

recently dredged sites. Significantly, dredging can cause changes in surface (sediment-water 

interface) and subsurface (pore water) oxygen concentrations. Since marine sediments are 

anoxic at some depth below the sediment-water interface (Fenchel, 1969), dredging often 

removes the upper, oxygenated strata. In addition, naturally occurring sulfide and ammonia 

may be mobilized by dredging (Mayer et al., 1991). Sulfide is naturally present in the top layers 

of marine sediments, and is toxic to a variety of benthic animals (Wang and Chapman, 1998). 

Post-larvae have been shown to avoid recently disturbed sediments (Woodin et al., 1995; 

Marinelli and Woodin, 2002). Woodin et al. (1995) found that recently settled juveniles of the 

polychaetes Nereis vexillosa and Arenicola cristata discriminate between undisturbed sediments 

and recently disturbed substrata with subsurface sediment exposed, such as that which occurs 

with dredging. Juvenile N. vexillosa and A. cristata rejected or were significantly slower to 

burrow into disturbed sediment surfaces. Processes determining pore-water oxygen 

composition may drive the acceptability of sediments to new recruits (Marinelli and Woodin, 

2002). 

Mobilized contaminants like ammonia may provide negative cues of habitat suitability, causing 

benthos to avoid recently disturbed sites (Engstrom and Marinelli, 2005). Hypoxia, anoxia, and 

chemical contamination may inhibit faunal recruitment for some period of time after cessation of 

dredging, until substratum reworking and subsurface and near-bottom shear flow ameliorate 

adverse hydrologic conditions. Because of the dynamic wave and current energies of the study 

area, hydrologic impairment in a mined site likely would be of short duration following cessation 

of dredging. In coarse sediment habitats with strong currents and wave action, subsurface 

hydrology provides deeper oxygenation and more rapid flushing of interstitial water (Revsbech 

et al., 1980). 
MMS Study 2010-010

58 

Infauna and epifauna recruit into dredged sites via larval settlement and post-larval migration 

across the seabed. Typically the initial stages of recolonization primarily involve opportunistic 

species, and longer-lived taxa colonize after the initial stages. Longer time frames are usually 

required for benthic assemblage composition of a dredged site to attain similarity with adjacent 

nondisturbed areas. The nature of biological recovery, including the speed of colonization and 

benthic assemblage composition, will depend in large measure on physical characteristics of a 

site after dredging and species-specific patterns of larval supply, both aspects often subject to 

high temporal variation. 

Compared to intertidal and hard bottom benthos, invertebrate larvae of soft sediment subtidal 

systems have a higher proportion of planktonic forms capable of an extended period of viability 

(Grantham et al., 2003), and potentially may be dispersed across large spatial scales. It is not 

clear, however, that long-range transport of larval recruits is necessary for benthic community 

recovery in mined sites on the inner shelf. 

Many invertebrate larval forms are adapted for rapid metamorphosis and short-range dispersal. 

Marine-invertebrate phyla share the developmental trait of metamorphic competence, a state in 

which nearly all requisite juvenile characters are present in the larva prior to settlement 

(Hadfield et al., 2001). Competence and consequent rapid metamorphosis in marine 

invertebrate larvae are conjectured to have arisen because they allow larvae to continue to 

swim and feed in the planktonic realm while simultaneously permitting extremely fast 

morphological transition from larval locomotory and feeding modes to a different set of such 

modes that are adaptive to life on the sea bottom (Hadfield et al., 2001). 

Marine invertebrate larvae are broadly classified as either planktotrophic or lecithotrophic. 

Planktotrophic larvae feed and mature in the water column, and have potential for long-distance 

dispersal. Lecithotrophic larvae are nonfeeding with comparatively limited dispersal. A number 

of larval forms do not fit neatly into either of these two categories (Hines, 1986a), however, and 

recent descriptions of larval development and life histories suggest that facultative feeders and 

other intermediate forms are not as rare as commonly assumed (Allen and Pernet, 2007). 

Moreover, some benthic invertebrates commonly exhibit poecilogony, which is the presence of 

variable larval development modes within a species. Groups exhibiting poecilogony include 

common study area inhabitants such as nudibranchs (West et al., 1984; Sisson, 2002) and 

spionid polychaetes (Gibson and Gibson, 2004). In some cases different larval forms have 

been observed within the same population (Sisson, 2002). Such flexibility in population life 

histories of inner shelf benthos may be adaptive in an environment that is dynamic across 

multiple spatial and temporal scales. 

A long-held assumption of larval life history traits is that planktotrophic forms evolved due to 

selective advantages of dispersal; however, pelagic larval stages may be adaptive primarily for 

entering a different trophic compartment, and dispersal may only be a by-product of that 

strategy (Giangrande et al., 1994). Species patterns in shallow shelf waters may in some cases 

be set by larval habitat selection and juvenile immigration from the local community (Snelgrove 

et al., 2001). 

Osman and Whitlatch (1998) found that recruitment, abundance, and dominance within subtidal 

bryozoan and ascidian communities in southern New England persist year after year over large 

areas of the bottom, and they suggested that such persistence results from strong local control 

of recruitment that overrides any variability in larval production and dispersal of species from 

outside a site. Pelagic lecithotrophic larvae of some marine populations may be behaviorally 

constrained to minimize transport even in highly dispersive environments with strong tidal 
MMS Study 2009-XXX

59 

currents, resulting in spatial domination by a few, local species (Todd, 1998). Many of the 

abundant shoal-inhabiting taxa of the study area produce lecithotrophic larvae, including 

tunicates and nudibranchs. Gammarid amphipods, another common inhabitant of the shoals, 

are brooders without a larval stage (Barnes, 1980). Bivalves generally produce pelagic 

planktotrophic larvae. Surf clam eggs are planktotrophic, and fertilization occurs in the water 

column above beds of spawning clams (Ropes, 1980). The greatest concentrations of surf 

clams offshore the Delmarva Peninsula occur at depths of 18 to 36 m (Ropes, 1978), coinciding 

with depths near Weaver Shoal. Potential surf clam recruits may therefore originate locally. 

The evolution of local recruitment may be due to adaptive advantages of remaining in habitats 

suitable for population maintenance (Strathmann et al., 2002). 

Decapod crustaceans are important community constituents in the offshore study area, though 

larvae may not originate in the immediate vicinity of the shoals. Adults of the abundant 

decapods of the study area occur along a continuum from estuaries to the open ocean, at 

varying abundance levels depending on season. Rock crabs (Cancer spp.) occur in estuaries 

and nearshore shelf locations primarily during colder months and move offshore during warmer 

months (Winget et al., 1974; Haefner and Van Engel, 1975; Haefner, 1976). Spider crabs 

(Libinia spp.) are most common in coastal waters during summer (Winget et al., 1974). Stehlik 

et al. (2004) found that lady crabs were most abundant in the Hudson-Raritan estuary between 

June and December. 

Decapods often form mating aggregations, timed with female molting (Barnes, 1980). Inlets and 

other locations near areas of tidal flow may serve as aggregation sites for mating or as 

spawning sites for some decapods (Brookins and Epifanio, 1985; DeGoursey and Auster, 1992; 

Drake et al., 1998). Female blue crabs migrate from low salinity estuarine regions to high 

salinity regions near the mouths of estuaries prior to release of larvae (Carr et al., 2004; Aguilar 

et al., 2005). Stehlik et al. (2004) suggested that estuarine use by lady crabs may be related to 

reproduction, and Modlin (1962) found that female sevenspine bay shrimp migrated into a 

Connecticut estuary prior to larval release. 

Proximity to estuarine inlets may promote entrainment of released decapod larvae by ebb tidal 

currents, transporting them to shelf waters where they develop. Larvae of blue crab, lady crab, 

rock crabs, sevenspine bay shrimp, and spider crabs develop through multiple zoeal stages in 

surface waters of the inner continental shelf. A post-larval stage (megalops) usually begins a 

benthic phase. Pelagic larvae of abundant decapods appear primarily during warmer months in 

the Mid-Atlantic Bight (Sandifer, 1973; Haefner, 1979; Dittel and Epifanio, 1982), though 

sevenspine bay shrimp larvae have been found to be abundant from late winter into spring 

(Sandifer, 1973; Wehrtmann, 1994). A pool of decapod larvae may exist seasonally in waters of 

the study area (Brookins and Epifanio, 1985), though larval cohorts tend to occur in discrete 

patches. Potential mechanisms for larval patch formation and maintenance include 

synchronous spawning events, associative larval behavior, and aggregative physical processes 

(Natunewicz and Epifanio, 2001). 

Decapod larvae and post-larvae exhibit behavioral responses to physical environmental cues, 

resulting in dispersal patterns that may differ from patterns predicted based on large-scale 

hydrographic forces (Hines, 1986b). Crab larvae may regulate their vertical position in the water 

column in response to environmental cues or endogenous biological rhythms (DeVries et al., 

1994; Forward et al., 1997; Garrison, 1999). Larvae may enter the water column on flood tides 

to be transported back into the estuary (Dittel and Epifanio, 1982), or remain on or near the 

bottom as a mechanism for retention in shelf waters (Epifanio, 1988; Zeng and Naylor, 1996). 

Epifanio (1988) found that lady crab larvae on the inner shelf remained nearer the substratum, 
MMS Study 2010-010

60 

whereas blue crab larvae, which return to estuaries during the megalops stage, remained close 

to the water surface. Individual behavior thus promotes retention of larval decapods in the 

vicinity of their parental populations, and this assures sufficient recruits for population 

maintenance (McConaugha, 1992). 

The ability of fish populations to recolonize dredged shoals in the region is largely unexamined. 

Broad patterns may vary based on the degree of bottom-association, which can range from 

direct (e.g., flounder species living in the sediment) to highly indirect. In the latter case, species 

such as Atlantic mackerel or striped bass may associate with shoal features in transient 

manners associated with movements of schools (Able and Fahay, 1998). In transects north of 

the study shoals, 33 of 47 species collected included age-0 juveniles and 25 species were near 

settlement size (Steves et al., 1999). However, the scaling and habitat variability that can 

influence abundances is highly species-specific and can involve very different meso- and 

macro-scale drivers (Sullivan et al., 2000). Complex temporal variations in shoal use, including 

substantive diel variations, are driven in part by feeding cycles (Slacum et al., 2006). Recovery 

of fish populations will necessarily include the reestablishment of fundamental trophic functions. 

4.5 SHOALS AS ESSENTIAL FISH HABITAT (EFH) 

4.5.1 Management and Species Categories 

Specific values of shoal habitats to Mid-Atlantic Bight fishes have been increasingly detailed in 

terms of both micro- and meso-scale habitat features (Diaz et al., 2003; Slacum et al., 2006; 

Vasslides and Able, 2008) with empirical reinforcement of EFH roles of offshore shoals. EFH is 

defined as “those waters and substrate necessary to fish for spawning, breeding, feeding or 

growth to maturity” [16 U.S.C. § 1801(10)]. The EFH final rule summarizing EFH regulations 

(50 CFR Part 600) outlines additional interpretation of the EFH definition. All eight Federal 

fishery management councils were mandated to amend management plans to identify EFH and 

anthropogenic threats by late1998. The Mid-Atlantic Fishery Management Council (MAFMC), 

with jurisdiction for Federal waters from Virginia to New York, identified EFH in amendments to 

the six fishery management plans that the council administers: spiny dogfish; Atlantic mackerel, 

squid, and butterfish; bluefish; summer flounder, scup, and black sea bass; surfclam and ocean 

quahog; and tilefish. Some of these species or other species that use shoals are also managed 

at the State and regional levels. 

Table 4.7 summarizes the Federal, regional, and State managed fish species that can occur in 

association with the shoal features in the current study. Managed fish species include at least 

15 bottom-associated species and at least 6 pelagic species that can associate with shoals. 

The bottom-associated fishes include flounders, rays, and sharks. Eight species, four demersal 

and four pelagic, had EFH designations within MAFMC jurisdiction. These shoals are also used 

by significant pelagic species such as the striped bass, which may use prominent bathymetric 

features such as our study sites for positioning and feeding during seasonal longshore 

migrations. 
MMS Study 2009-XXX

61 

Table 4.7. Managed fish and invertebrate species that can utilize offshore sand shoals in the 

Mid-Atlantic Bight. Management agencies include: Mid-Atlantic Fishery 

Management Council (MAFMC); Atlantic States Marine Fishery Commission 

(ASMFC); several State fishery management agencies; National Marine Fisheries 

Service (NMFS), and New England Fishery Management Council (NEFMC). The 

Federal MAFMC and NMFS have primary fishery authority of the shoals in the 

present study. FMP Amd: Fishery Management Plan Amendment. HMS: Highly 

Migratory Species rules, NMFS.

Managed Fishes 

Scientific Name Common Name 

MAFMC EFH 

Designation ASFMC Other 

Pelagic 

Morone saxatilis Striped bass None Yes 

Pomatomus saltatrix Bluefish FMP Amd 1 Yes 

Scomber scombrus Atlantic mackerel FMP Amd 8 No 

Peprilus triacanthus Butterfish FMP Amd 8 No 

Stenotomus chrysops Scup FMP Amd 12 Yes 

Clupea harengus Atlantic herring No Yes 

Demersal 

Paralichthys dentatus Summer flounder FMP Amd 12 Yes 

Centropristis striata Black sea bass FMP Amd 12 Yes 

Lophius americanus Monkfish No, NEFMC No 

Scophthalmus aquosus Windowpane flounder None No NEFMC 

Lopholatilus chamaeleonticeps Tilefish FMP Amd 1 No 

Squalus acanthias Spiny dogfish Original FMP Yes NEFMC 

Micropogonias undulatus Atlantic croaker None Yes 

Leiostomus xanthurus Spot None Yes 

Pseudopleuronectes americanus Winter flounder None Yes NEFMC 

Urophycis chuss Red hake None No NEFMC 

Odontaspis taurus Sand tiger shark None Yes HMS 

Cetorhinus maximus Basking shark None Yes HMS 

Carcharhinus limbatus Blacktip shark None Yes HMS 

Sphyrna lewini Scalloped hammerhead None Yes HMS 

Carcharhinus signatus Night shark None Yes HMS 

Carcharhinus brevipinna Silky shark None Yes HMS 

Carcharhinus obscurus Dusky shark None Yes HMS 

Carcharhinus plumbeus Sandbar shark None Yes HMS 

Galeocerdo cuvieri Tiger shark None Yes HMS 

Rhizoprionodon terraenovae Atlantic sharpnose shark None Yes HMS 

Federally and state managed invertebrate species include three bottom-associated species and 

two pelagic species (Table 4.8). Both groups are under differing management and, potentially, 

very different invertebrate responses to sediment mining exist (e.g., quahog in comparision to 

squid). 

Table 4.8. Managed invertebrate species that can utilize offshore sand shoals in the 

Mid-Atlantic Bight. Abbreviations provided in Table 4.7. 

Managed Invertebrates 

Species Name Common Name 

MAFMC EFH 

Designation ASFMC Other 

Pelagic 

Loligo pealei Long-finned squid FMP Amd 8 No 

Illix illecebrosus Short-finned squid FMP Amd 8 No 

Bottom-associated 

Spisula solidissima Surfclam FMP Amd 12 No 

Arctica islandica Ocean quahog FMP Amd 12 No 

Limulus polyphemus Horseshoe crab None Yes 
MMS Study 2010-010

62 

Due to the breadth of the original EFH definition, the EFH guidelines also recognized subunits 

termed Habitat Areas of Particular Concern (HAPC) that could involve four criteria: 

(1) importance of ecological functions; (2) sensitivity to degradation; (3) probability and extent of 

effects from development; and (4) rarity. The MAFMC designated submerged aquatic 

vegetation (SAV) and macroalgae beds in nursery habitats as HAPC for juvenile and 

larval-stage summer flounder (MAFMC, 1998a). The Council did not identify HAPC for other 

species, concluding they did not have enough information to link habitat type with recruitment 

success (MAFMC, 1998b). The EFH Amendment notes the importance of these habitat types in 

providing summer flounder shelter from predators and prey, the first HAPC criterion. The 

MAFMC did not propose any special regulations for the areas designated as HAPC. The 

Amendment implies that the reason for this is that the majority of the designation is in state 

waters, where the Council does not have the authority to regulate fishing (Dobryzinski and 

Johnson, 2001). 

4.5.2 Functional Values 

The assessment of species and life stages associated with Mid-Atlantic Bight sand shoals in 

Section 4.2 suggests that particular ecological functions of shoals can be evaluated. At broad 

spatial scales (1 to 100 km2

; macro), fishes may be using shoal features as guideposts during 

migrations, local movements, or spawning. At intermediate scales (10’s to 100’s m2

; meso), 

different parts of individual shoals may represent different foraging areas or shelter from 

predators or waves and currents. At smaller scales (e.g., cm2

 to m2; micro), sediment texture 

(fine sand to shell fragments), variable bedform structures, and biogenic structures can be 

important as predator refuge or foraging areas. Considering this spatial framework, most 

fundamental ecological functions of shoals for fishes fall into the categories of spawning, 

shelter, or foraging. 

4.5.2.1 Spawning 

Spawning times and general locations are known for some Mid-Atlantic Bight species, and there 

are some general patterns that occur (Colton et al., 1979; Wilk et al., 1990). Evidence for 

spawning times comes from extensive egg and larval surveys and the examination of ovaries of 

mature adults (Colton et al., 1979; Wilk et al., 1990). Spatial and temporal distribution of eggs 

and early (pre-flexion) larvae are indicators of spawning. This has ramifications for the habitat 

function of shoals. One pattern of spawning by coastal fishes is to spawn in outer shelf waters 

often during winter months. Variations to this pattern are spawners that move offshore and 

south as far as Cape Hatteras to spawn (Cowen et al., 1993). 

Other demersal species spawn in inner shelf waters without moving north or south. Wilk et al. 

(1990) followed ovarian development of 14 species including several known to be associated 

with shoals. Black sea bass, silver hake, red hake, butterfish, northern searobin, striped 

searobin (Prionotus evolans), and fourspot flounder (Paralichthys oblongus) spawn in summer 

months. Summer and winter flounder are offshore fall and winter spawners. Summer flounder 

spawning peaks in October and November as they migrate from estuaries to the OCS. This 

puts their spawning events into relatively close cross-shelf proximity to shoal systems. Exact 

locations of spawning relative to shoals are unknown for most fish species. 

Precise spawning locations are not known from many species; however, based on the collection 

of early stage larvae, Able and Hagan (1995) and Able et al. (2006) showed that several taxa, 

including bay anchovy, spawn on the inner shelf in water depths similar to those of the focal 

shoals. However, species such as Anchoa also spawn inshore including euhaline estuarine 
MMS Study 2009-XXX

63 

areas. A clupeid and scombrid (bay anchovy and Atlantic mackerel) had the highest average 

numbers of eggs collected at Beach Haven Ridge, New Jersey, during the 1970’s (Able and 

Hagan, 1995). 

In contrast to inner and outer continental shelf spawners, anadromous species such as the 

striped bass spawn water-column eggs upstream in tributaries within estuaries of many major 

Mid-Atlantic Bight and New York Bight watersheds. In another life history variation, winter 

flounder spawn demersal eggs in estuaries. In the latter two species use of shoal habitats 

doesn’t begin until at least one year and sometimes several years of estuarine maturation 

before consistent seasonal offshore migrations begin.

4.5.2.2 Shelter 

The diversity of species of temperate shoal habitats and adjacent areas can be high, for 

example, 93 species from 47 families represented (Able and Hagan, 1995). Many demersal 

fishes of the region are characterized by complete age-class migrations across the shelf every 

approximate six months and associate with benthic habitats on a variety of spatial scales (Able 

and Fahay, 1998; Sullivan et al., 2000, 2006). At large scales (10’s to 100’s m2

), ridges and 

swales provide relief and habitat complexity, but for settling and juvenile fishes, structure at 

smaller scales (cm2

 to m2) is more important (Diaz et al., 2003). Small-scale structure used by 

juvenile fishes as refuge from predation can be either physical (sand waves or bedforms) or 

biogenic (shell fragments, worm tubes, feeding pits, and other bioturbation) in nature. 

Diaz et al. (2003) reported high fish densities associated with highest sand waves and 

concentrated worm tube aggregations on the inner continental shelf. Black sea bass juveniles 

prefer areas with accumulations of shells and shell fragments (Able et al., 1995). Auster et al. 

(1995) found young fishes on the outer shelf associated with a variety of small features such as 

sand waves, coarse material accumulated in the troughs of these waves, biogenic depressions 

(skate or ray feeding pits), clay outcrops, and boulders. It is likely that species utilizing shoals 

and surrounding areas would seek out similar microhabitats (Able et al., 1995; Diaz et al., 

2003). 

In areas where the seafloor is devoid of physical structure, both predators and prey must be 

able to burrow into the sediments for concealment. Several demersal species such as flatfishes 

(Paralichthyidae, Scophthalmidae, Pleuronectidae), searobins (Prionotus spp.), stargazers 

(Uranoscopidae), sand lances (Ammodytidae), and conger eels (Congridae) burrow or partially 

bury themselves in the sand. This phenomenon has not been formally studied, but such activity 

would require particular sediment size ranges and compaction characteristics; attributes that 

could be modified with excavation, particularly at erosional shoal areas. An additional but 

unstudied aspect of this behavior is that many species that burrow or are buried during the day 

emerge at night to forage under the guise of darkness (Auster et al., 1995). 

Several of the demersal species that associate with shoals are known to also occur on artificial 

or naturally occurring hard bottom in the region (Eklund and Targett, 1991; Steimle and Zetlin, 

2000). Most notable of these is the black sea bass, followed by red hake, conger eel (Conger 

oceanicus), and scup. This suggests that at least some of the demersal species have an affinity 

for high relief structure; perhaps shoals provide some element of this and serve as shelter or 

spawning sites. Habitat for pelagic species is generally determined by water column 

characteristics but can include artificial or natural structures. Habitat association may occur at a 

variety of spatial scales. Level sedimentary bottoms appear featureless at large scales; 

however, when viewed at finer scales, the details of bed form, bioturbation, sand waves, and 
MMS Study 2010-010

64 

sediment texture emerge as important for individuals of varying life stages. However, the role of 

shoals in transient movements, sometimes associated with seasonal cross-shelf migrations, is 

poorly known for most benthic and pelagic species. 

Able et al. (2006) noted that several of the important Mid-Atlantic Bight fishes settled in both 

estuaries and coastal ocean waters. This distinction is important when interpreting the 

assumption of estuarine dependence in young fishes of many species. It appears that species 

settling in either estuaries or coastal oceans are growing and surviving at similar rates in the two 

habitats. Able et al. (2006) found only fourspine stickleback (Apeltes quadracus), naked goby 

(Gobiosoma bosc), and winter flounder (Pseudopleuronectes americanus) in estuarine waters. 

Nonresident species that settled exclusively in estuaries were tautog, dusky pipefish, weakfish, 

and cunner. Species settling in both estuarine and coastal ocean habitats included American 

sand lance (Ammodytes americanus), black seabass, seaboard goby, windowpane, red hake, 

Atlantic croaker (Micropogonias undulatus), smallmouth flounder, northern searobin, spotted 

hake, and stripped searobin. 

There are special examples of symbiosis between juvenile red hake and the sea scallop 

Placopecten magellanicus (Steiner et al., 1982). Red hake reside within the mantle cavity of the 

scallop following settlement from a size of 30- to 116-mm standard length. Also, the inquiline 

snailfish (Liparis inquilinus) spends its entire adult life in a live sea scallop. Many demersal and 

pelagic species in the Mid-Atlantic Bight may use habitats in a facultative manner (e.g., 

similar-sized individuals may utilize different habitats at the same time) (Able et al., 2006). The 

pattern of settlement exhibited by these species was further supported from autecological 

studies on black sea bass (Able et al., 1995), windowpane (Morse and Able, 1995; Neuman and 

Able, 2002), and searobins (McBride et al., 1998). This latter group of species, particularly 

black sea bass and windowpane flounder, are relevant to the discussion of the importance of 

shoals as EFH in the region. Understanding the relative importance of different habitats to 

opportunistic species remains a continuous challenge for resource managers in tropical and 

temperate systems, as an absence of dependent usage doesn’t mean that a habitat may not 

have significant value (Lindeman et al., 2000; Able et al., 2006). 

4.5.2.3 Foraging 

Feeding habits of demersal fishes of the region have been summarized by recognizing that 

several dietary guilds exist (Garrison and Link, 2000). Dietary guilds are composed of species 

exploiting similar food resources on the open shelf. These guilds include crab eaters, 

planktivores, amphipod/shrimp eaters, shrimp/small fish eaters, benthivores, and piscivores 

(Garrison and Link, 2000; Link, 2002). The composition of particular feeding guilds depends 

upon morphological characteristics that change with growth of the fish. Thus, many species will 

change guild associations as they grow. Sissenwine (1984) characterized the northeast 

continental shelf ecosystem as predator-dominated. From the available information, it is 

conceivable that shoals provide either concentrations of invertebrates or more easily accessible 

prey due to the physical nature of the feature. This may be especially common in areas around 

the base of shoals. 

The affinity of certain demersal fishes for particular sediment types often is related to the types 

of prey items supported by those sediments. Species such as skates, Atlantic croaker, spot, 

and winter flounder are bottom feeders that consume infaunal and epibenthic crustaceans and 

polychaetes. Amphipods are known to be important in the diets of some demersal fishes, 

including cod, haddock, and winter flounder. Certain demersal foragers may therefore be 
MMS Study 2009-XXX

65 

attracted to areas of medium to coarse sands, where crustaceans and polychaetes are most 

abundant (Wigley and Theroux, 1998). 

Pelagic groups of shoal-associated fishes may be divided into large bodied piscivores and 

smaller bodied planktivores. Forage species are attracted to shoals or other high relief features 

because of hydrodynamics and their effects on the prey capture. Piscivores include Spanish 

mackerel, bluefish, striped bass, and sharks. These species comprise the predatory 

component, whereas the smaller planktivores such as anchovies, Atlantic menhaden, herrings, 

alewives, and shad form the prey component of the pelagic assemblage. This connection 

between predatory species and their prey has been well documented for striped bass (Overton 

et al., 2007). Many of the piscviorous predators such as bluefish and striped bass are attracted 

to concentrations of clupeoid prey (herrings and anchovies) that may form in association with 

shoals. Overton et al. (2007) documented that coastal populations of striped bass fed primarily 

on bay anchovy and Atlantic menhaden—two species regularly collected around shoals of the 

region. Shoals may also affect circulation patterns in such a way that planktonic prey are more 

readily obtained by water column foragers. 

4.6 SHOAL HABITATS IN COMPARISON TO OTHER CROSS-SHELF FEATURES 

Many geomorphological features of offshore shoals can promote increased, localized biological 

productivity. Fish usage of the habitats within many physiographic gradients across the shelf 

was characterized to examine the comparative roles of spatially distinct cross-shelf 

macrohabitat features, and temporal variability of their use. These features are influenced by 

inshore estuarine habitats and inlet passages to the ocean, in addition to the raised bathymetric 

profiles that shoal systems such as Weaver/Isle of Wight present to any organisms that annually 

transit the shelf as part of their life history (Able and Fahay, 1998; Maa et al., 2004). 

The assessment of species distributions across an entire shelf, and on the finer scale of 

structural bottom types, is limited by the absence of empirical data, and also larger spatial 

frameworks that incorporate both small-scale structural and large-scale physiographic attributes 

within a cross-shelf continuum. Such a framework should explicitly characterize several spatial 

scales across heterogeneous seascapes, reflect temporally variable ontogenetic migrations and 

be of use to administrators charged with decision-making in areas with varying levels of 

baseline data. 

4.6.1 Characterizing Cross-shelf Gradients and Habitats 

A spatial framework for assessing habitat use was developed following the above goals. The 

specific objectives in developing this cross-shelf habitat (CSH) framework were to (1) define 

spatial scales for structural bottom-types and their physiographic backdrops (cross-shelf strata); 

(2) integrate these features using a matrix that combines a structural axis and a physiographic 

axis in a geographically logical manner; and (3) apply CSH matrices of habitats within strata to 

examine distributions and coarse relative abundance patterns among the primary habitats of the 

heterogeneous seascape under study (Lindeman et al., 1998; Ault et al., 1999). 

Two spatial scales were emphasized: structural habitats and cross-shelf strata. Habitats were 

defined as structural bottom-types on spatial scales of 0.1 to 1 m3

 that provide shelter or trophic 

resources. Twelve natural habitat types, noninclusive for all of the structural combinations 

present, were used based on the literature for the region and assigned mnemonic acronyms 

(Table 4.9). Ten cross-shelf strata, were postulated to extend from inshore mainland areas to 

the outer shelf east of the study area. These strata were based on (1) bathymetry; and 
MMS Study 2010-010

66 

(2) cross-shelf positioning relative to emergent sedimentary barrier islands and submerged 

shoals. 

Table 4.9. Structural habitat types occupying volumes of 1 m3

. 

Habitat Category Habitat Type 

Fine sediments 

Sediment Coarse sediments 

Shell 

Diopatra tubes 

Invertebrate Structure Asabellides 

Other 

Zostera 

Submerged Aquatic Vegetation Macroalgae 

Combination 

Spartina alterniflora 

Emergent Vegetation Juncus 

Phragmites 

From inshore to offshore, the cross-shelf strata used were: Mainland Shore, 0 to 2 m; Basin 

Axis, >2 m (e.g., Isle of Wight Bay); Leeward Shore, 0 to 2 m; Inlet Axis, >2 m (e.g., Ocean City 

Inlet); Inshore Shallow, <4 m; Inshore Deep, 4 to 15 m; Mid-shelf Shallow; Leading Edge of 

Shoal; Trailing Edge of Shoal; Mid-shelf Deep. For both habitats and cross-shelf strata, the 

specific named categories are nominal: future iterative revision is encouraged. 

Intersections of individual habitat types and cross-shelf strata form cells or cross-shelf habitats 

within the matrix. For example, one cross-shelf habitat is fine sediment within the axis of a 

channel in a barrier island inlet (IA). At least 116 cross-shelf habitats were nominally identified. 

Cross-shelf habitat attributes of offshore shoals were emphasized as a heuristic aid to questions 

in Section 6 on dredge alternatives for different shoal areas. Physiographic gradients 

associated with shoals are influenced by depositonal patterns and can include leading edge of 

shoal, trailing edge of shoal, and trough, flank, and crest subareas. 

Four of the cross-shelf strata were within estuarine areas inside ocean inlets (e.g., Isle of Wight 

Bay and Ocean City Inlet). Six others extended from oceanic channels of the barrier islands to 

the outer shelf edge. These strata are proxies for gradients of other physical variables often 

correrelated with depth and cross-shelf position (e.g., salinity, turbidity, and wind exposure) that 

can distribute in semi-continuous bands across the shelf. Since fish usage of similar structural 

habitats may vary along physically different sections of shelves, cross-shelf strata can represent 

bio-physical gradients following Keddy (1991), who suggested that environmental gradients are 

useful but often underused research tools. 

4.6.2 Cross-shelf Patterns of Habitat Use Among Some Demersal and 

Pelagic Species 

A CSH matrix of primary habitat combinations from the OCS into the northern Delaware 

estuaries was generated by superimposing structural habitats on a vertical axis and cross-shelf 

strata on a horizontal axis. Four fish species representative of differing life history strategies 

and benthic and pelagic water column positioning were used to populate cross-shelf habitat 

matrices by seasons and key life stages. The species represented several significant life history 

patterns, economic interests, and trophic drivers and included summer flounder and 

windowpane, abundant flatfishes that undergo substantial cross-shelf migrations and are 
MMS Study 2009-XXX

67 

harvested significantly. Also examined were bay anchovy, an abundant and widely distributed 

baitfish and prey item, and striped bass, an anadromous gamefish that can distribute widely 

across the shelf. 

The literature used to estimate cross-shelf distributional patterns and coarse relative 

abundances across estuarine to OCS cross-shelf gradients included reviews (Able and Fahay, 

1998; VIMS, 2000; Able et al., 2007), empirical studies for the project area (e.g., Diaz et al., 

2003; Slacum et al., 2006), and empirical studies from the shoal study area off New Jersey, 

Beach Haven Ridge (e.g., Able and Hagan, 1995; Able et al., 2006). Combinations of 

cross-shelf habitats that are used abundantly can be termed habitat mosaics. Several 

combinations of spatial scales were examined depending on the organisms, life stages, and 

processes of interest to expose habitat mosaics of interest in terms of bio-physical dredging 

issues or data needs. 

The summer flounder is an example of an economically important sediment-dwelling species 

that engages in substantial cross-shelf migrations repeatedly through its life cycle (Able et al., 

1990; Able and Kaiser, 1994). For some of the summer flounder subpopulations within this 

range of the Mid-Atlantic Bight, these migrations probably involve the shoals in the present 

study (Diaz et al., 2003). Figures 4.3 and 4.4 show the estimated summer and winter array of 

cross-shelf habitats used by the summer flounder, with relative abundances for summer and 

winter, July and January, respectively. Evidence suggests that almost all adults are out of the 

region’s estuaries by November or December (Able and Fahay, 1998). Use of the study shoals 

is particularly likely for cross-shelf migrators that emigrate out of Ocean City Inlet. 

Some of the most prominent patterns of cross-shelf habitat use for summer flounder include the 

absence of settlement in ocean environments and the biannual, long cross-shelf migration 

juveniles and adults make from estuaries to overwinter offshore. As seen in Figure 4.3, these 

migration events potentially place juvenile and adult life stages of summer flounder into multiple 

combinations of habitats within diverse cross-shelf gradients. Almost all of the cross-shelf strata 

between estuaries and the deeper shelf (>100 cross-shelf habitat cells), including the project 

shoals, are potentially bidirectionally transited by the same individual fishes on two long 

migrations per year (Figure 4.3), perhaps using very similar paths that ultimately traverse 

several tens of kilometers. The decision making by these fishes requires further investigation, 

perhaps by modeling of habitat selection decisions. 

The windowpane flounder is an important flatfish that differs from summer flounder in 

cross-shelf habitat usage in some attributes. At the broadest scale, it is not an estuarine-only 

settler, instead settling in both estuarine and ocean environments (Morse and Able, 1995; Able 

et al., 2006). Figure 4.4 shows relative abundance estimates among cross-shelf strata and 

habitats within. Neuman and Able (1998) found that windowpane of all sizes preferred sand 

over mud, but there were differences in sediment preference, burial behavior, and pigment 

between transitional larval and juvenile stages. Numbers of juveniles can be substantially 

higher in ocean areas, though juveniles can occur abundantly in estuaries. The patterns are 

complicated, for example, Neuman et al. (2001) and Neuman and Able (2002) found that growth 

and settlement patterns varied with season of spawning. Evidence suggests that 

spring-spawned age classes occurred in both ocean and estuary areas, whereas fall-spawned 

cohorts settled predominantly in the ocean (Morse and Able, 1995). 
68

__________________________________________________________________________________________________Summer Flounder Cross-shelf Gradient Adults |----Estuary---------------------------------------------------------------------Ocean---------------------------------

Summer (July), Winter (January)  Barrier Island and Channel  |-------------------- Shoals ---------

Habitat MS BA LS IA IS ID MSS TR LEFL CR 

Fine █ █ ▄ █ ▄ █ ▄ █ ▄ ▄ ▄ ▄ █ ▄ █ ▄ █ ▄ █ 

Coarse █ Sediment █ ▄ █ ▄ █ ▄ █ ▄ ▄ ▄ ▄ █ ▄ █ ▄ █ ▄ █ 

Shell █ █ ▄ █ ▄ █ ▄ █ ▄ ▄ ▄ ▄ ▄ ▄ ▄ 

Diopatra ▄ ▄ ▄ ▄ ▄ ▄ 

Asabellides ▄ ▄ ▄ ▄ ▄ ▄ 

Invertebrate Structure 

Other ▄ ▄ ▄ ▄ ▄ ▄ 

Zostera

▄ ▄ ▄ ▄

Macroalgae 

▄ ▄ ▄ ▄

Submerged 

Aquatic 

Vegetation 

Combination 

▄ ▄ ▄ ▄

Spartina 

▄ ▄

Juncus 

▄ ▄

Emergent 

Vegetation

Phragmites 

▄ ▄

Gradients associated with shoals: LE = leading edge; TE = trailing edge. Shoal subareas: TR = trough; FL = flank; CR = crest. Physica

gradients cited in text: MS = Mainland Shore; BA = Basin Axis; LS = Leeward Shore; IA = Inlet Axis; IS = Inshore Shallow; ID = Inshore D

Shallow; MSD = Mid-shelf Deep. 

Figure 4.3. Estimates of summer flounder (Paralichthys dentatus) cross-shelf distribution and relative abundanc

during summer and winter, stratified according to habitat and physical cross-shelf gradient. Solid baabundance ranks based on high, low, and rare or no occurrence derived from literature cited in texthabitats that do not occur within certain cross-shelf gradients. 
69

__________________________________________________________________________________________________Windowpane Flounder Cross-shelf Gradient

Larvae and Early Juveniles |----Estuary------------------------------------------------------------------------Ocean---Summer (July), Winter (January)  Barrier Island and Channel  |--------------------- Shoals --------

Habitat MS BA LS IA IS ID MSS TR LEFL CR 

Fine 

▄ ▄ ▄ ▄ ▄ █ ▄ █ █ █ █ █ 

Coarse 

▄

Sediment ▄ ▄ ▄ ▄ █ ▄ █ █ █ █ █ 

Shell 

▄ ▄ ▄ ▄ ▄ █ ▄ █ ▄ ▄ ▄ ▄ 

Diopatra ▄ ▄ ▄ ▄ 

Asabellides ▄ ▄ ▄ ▄ 

Invertebrate Structure 

Other 

Zostera

▄ ▄ ▄ ▄

Macroalgae 

▄ ▄ ▄ ▄

Submerged 

Aquatic 

Vegetation 

Combination 

▄ ▄ ▄ ▄

Spartina 

▄ ▄ ▄

Juncus 

▄ ▄ ▄

Emergent 

Vegetation

Phragmites 

▄ ▄ ▄

Gradients associated with shoals: LE = leading edge; TE = trailing edge. Shoal subareas: TR = trough; FL = flank; CR = crest. Physica

gradients cited in text: MS = Mainland Shore; BA = Basin Axis; LS = Leeward Shore; IA = Inlet Axis; IS = Inshore Shallow; ID = Inshore D

Shallow; MSD = Mid-shelf Deep. 

Figure 4.4. Estimates of windowpane flounder (Scophthalmus aquosus) cross-shelf distribution and relative abu

larvae and early stage juveniles during summer and winter, stratified according to habitat and physi

gradient. Solid bars represent abundance ranks based on high, low, and rare or no occurrence dercited in text. Shaded cells reflect habitats that do not occur within certain cross-shelf gradients. 
MMS Study 2010-010 

70 

The bay anchovy is by many measures, one of the most important fishes of both estuaries and 

the inner continental shelf of the Mid-Atlantic Bight. Its distribution is ubiquitous compared to 

many species (Martino and Able, 2003) both in terms of cross-shelf strata and habitats 

(Figure 4.5), and can have less direct structural habitat associations than many species. In 

various studies, bay anchovy abundances surpass most or all other species of fishes (Able and 

Fahay, 1998; Martino and Able, 2003). The widespread distribution is most manifest in summer 

months when the species occurs abundantly in diverse water column habitats from estuarine 

tributaries to the inner continental shelf, including the area of the project shoals (Slacum et al., 

2006). 

The striped bass spawns in freshwater tributaries yet adults can occur thoughout the inner 

continental shelf. Like many pelagic fish species, striped bass undergo substantial seasonal 

migrations (Able et al., 2006). These migration events place striped bass into multiple 

combinations of habitats within diverse cross-shelf gradients on and between migrations in adult 

stages (Figure 4.6). Larvae and juveniles, however, are much more seasonally restricted to 

estuarine areas where they can show complex patterns of space use (Able and Grothues, 

2007), rarely occurring offshore in the winter (Able and Fahay, 1998). The migratory “paths” 

that flatfishes follow may be very specific to certain near-bottom habitat attributes. In contrast, 

for fast pelagic fishes like striped bass, high in the water column, offshore sand shoals may 

have somewhat differing roles in these migrations. For either life history pattern, prominent 

shoals could have functions as navigational bearings for long transits across the shelf, elevated 

energetic production as concentrated feeding areas, or other important life history functions 

(potential near-spawning areas for summer flounder). 

4.6.3 Cross-shelf Distributional Patterns of Demersal and Pelagic Species 

Several differing coastal fish assemblages of the Mid-Atlantic Bight and southern New York 

bight regions have been identified in prior studies. Steves et al. (1999) identified three 

cross-shelf zones with relatively distinct fishes (inner, middle, and outer) correlated in part with 

summer hydrographic fronts. Three species assemblages (inshore, near-ridge, and offshore) 

were identified by Vasslides and Able, 2008. The inner shelf fish species typically settle in 

estuaries or the ocean, or estuaries only, not in the ocean only (Able et al., 2006). Importantly, 

the majority of species that settle in both estuary and ocean settle more abundantly in ocean 

than estuarine areas. Many prominent fishes are driven to major, cross-shelf migrations every 

6 months by seasonal temperature changes, including many harvested drums and croakers 

(sciaenids), in addition to benthic flatfishes and coastal pelagics. The potential for high 

specificity in habitat use exists, but may also be masked somewhat by the frequent movements 

and underlying opportunism implied by such wide, estuarine to oceanic cross-shelf distributions. 

Among shoals of southern New Jersey, fish species richness was higher at near-ridge stations, 

especially in the fall during overwintering of many species (Vasslides and Able, 2008). Fall is 

the one season when bay anchovy are not abundant on the shoals, as this is an inshore 

spawning period. However, many other species are present in the fall (Figures 4.3 to 4.6). At 

various smaller habitat and microhabitat scales, there are a variety of drivers of observed 

diversity and abundance of fishes and invertebrates, including the length and height of bedforms 

and the density of biogenic structures (Diaz et al., 2003, 2004), fine-scale features that are 

difficult to measure at fine temporal or spatial scales. Probable diel differences include 

dispersal of various motile invertebrates away from dense biogenic structures (such as Diopatra

tube mats) at night. Slacum et al. (2006) found diel differences in pelagic fish abundances, but 

mechanisms are unknown. 
71

__________________________________________________________________________________________________Bay Anchovy Cross-shelf GradientLarvae and Early Juvenile |----Estuary--------------------------------------------------------------------------------Ocean----------------------Summer (July), Winter (January)  Barrier Island and Channel  |------------------------ Shoals ---------

Habitat MS BA LS IA IS ID MSS TR LEFL CR CR 

Fine █ █ █ ▄ █ █ █ █ █ █ █ █ █ 

Coarse █ █ Sediment █ ▄ █ █ █ █ █ █ █ █ █ 

Shell █ █ █ ▄ █ █ █ █ █ █ █ █ █ 

Diopatra █ █ █ █ █ 

Asabellides █ █ █ █ █ 

Invertebrate Structure 

Other █ █ █ █ █ 

Zostera █ █ █ ▄ █ █ █

Macroalgae █ █ █ ▄ █ █ █

Submerged 

Aquatic 

Vegetation 

Combination █ █ █ ▄ █ █ █

Spartina █ █ █ ▄ █ █ █

Juncus █ █ █ ▄ █ █ █ Emergent Vegetation

Phragmites █ █ █ ▄ █ █ █

Gradients associated with shoals: LE = leading edge; TE = trailing edge. Shoal subareas: TR = trough; FL = flank; CR = crest. Physica

gradients cited in text: MS = Mainland Shore; BA = Basin Axis; LS = Leeward Shore; IA = Inlet Axis; IS = Inshore Shallow; ID = Inshore D

Shallow; MSD = Mid-shelf Deep. 

Figure 4.5. Estimates of bay anchovy (Anchoa mitchilli) cross-shelf distribution and relative abundance ranks of 

stage juveniles during summer and winter, stratified according to habitat and physical cross-shelf grrepresent abundance ranks based on high, low, and rare or no occurrence derived from literature cicells reflect habitats that do not occur within certain cross-shelf gradients. 
72

__________________________________________________________________________________________________Striped Bass Cross-shelf Gradient Adults |----Estuary--------------------------------------------------------------------------------Ocean----------------------

Summer (July), Winter (January)  Barrier Island and Channel  |---------------------- Shoals ------

Habitat MS BA LS IA IS ID MSS TR LEFL CR 

Fine █ ▄ █ ▄ █ ▄ █ █ █ █ █ █ █ █ █ █ █ █ █ █ 

Coarse █ ▄ Sediment █ ▄ █ ▄ █ █ █ █ █ █ █ █ █ █ █ █ █ █ 

Shell █ ▄ █ ▄ █ ▄ █ █ █ █ █ █ █ █ █ █ █ █ █ █ 

Diopatra ▄ ▄ ▄ ▄ ▄ ▄ 

Asabellides ▄ ▄ ▄ ▄ ▄ ▄ 

Invertebrate Structure 

Other ▄ ▄ ▄ ▄ ▄ ▄ 

Zostera █ █ █ █ █ █ █ █

Macroalgae █ █ █ █ █ █ █ █

Submerged 

Aquatic 

Vegetation 

Combination █ █ █ █ █ █ █ █

Spartina █ █ █ █ █ █ █ █

Juncus █ █ █ █ █ █ █ █ Emergent Vegetation

Phragmites █ █ █ █ █ █ █ █

Gradients associated with shoals: LE = leading edge; TE = trailing edge. Shoal subareas: TR = trough; FL = flank; CR = crest. Physica

gradients cited in text: MS = Mainland Shore; BA = Basin Axis; LS = Leeward Shore; IA = Inlet Axis; IS = Inshore Shallow; ID = Inshore D

Shallow; MSD = Mid-shelf Deep. 

Figure 4.6. Estimates of striped bass (Morone saxatilis) cross-shelf distribution and relative abundance ranks o

summer and winter, stratified according to habitat and physical cross-shelf gradient. Solid bars repranks based on high, low, and rare or no occurrence derived from literature cited in text. Shaded ce

that do not occur within certain cross-shelf gradients. 
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In all cross-shelf habitat matrices (Figures 4.3 to 4.6), the cross-shelf gradient axis included 

trailing edge and leading edge strata with trough, flank, and crest habitats imbedded within. 

However, intra-shoal variations in relative abundances of the species examined do not differ 

within seasons. This is a function of limited data. There are some generic management 

assumptions regarding the relative productivity of flanks, troughs, and crests. For example, an 

NMFS EFH Stipulation from the Sandbridge, Virginia, lease, issued by MMS, states that “To the 

maximum extent possible, the dredging contractor remove surficial sediment from shoal flanks 

compared to shoal crests and adjacent troughs, areas that are generally more biologically 

productive.” The relative degree of site specificity for such conclusions can be very high, 

subject to high temporal variation, and high species-specific differences in habitat use. 

Troughs had the highest summer flounder numbers in the study area (Slacum et al., 2006). In 

the Maryland-Delaware shoals study by VIMS (2000) flanks and crests both yielded fewer 

species and less biomass than troughs. Some bivalves were more common along the crests 

(VIMS, 2000), and since bivalves are important contributors to secondary production, there 

potentially could be elevated impacts with the relative amount of biomass removed on a crest 

compared to a dredge site on a flank. Compared to abundance and diversity indices, biomass 

sometimes does take longer to recover in dredged sites (Newell et al., 1998). But larger, more 

mature bivalves generally are less commonly consumed by motile epifauna, such as sea stars 

and crabs, because of shell thickness. Loss of trophic function with the removal of sediments is 

a temporary consequence of dredging. Until recolonization occurs, motile foragers would feed 

in nearby nondredged areas. It isn't entirely clear that dredging a crest site results in greater 

impairment of ecological function compared to a flank site. And not all flanks are the same 

(Section 4.2), as there are differences in community patterns between the current-facing and 

lee sides of some shoals. 

In summary, data gathered from individual shoals confirmed that a diverse assemblage of 

demersal and pelagic fishes associate with regional sand shoals and potentially use these 

shoals for feeding, spawning, and growing to maturity. Benthic invertebrates that contribute 

structural fish habitat (worm tubes, burrows, and bioturbation) as well as a forage base for 

demersal feeders also associate with sand shoals. Field studies of adult fish species collected 

by trawl and gill nets confirm that benthic feeders such as skates, scup, drums, searobins, 

flounders, and black sea bass occur around shoals and adjacent sand bottom areas. These 

species are behaviorally and morphologically adapted for bottom feeding in sedimentary 

environments. Pelagic species such as bay anchovy, Atlantic menhaden, Atlantic mackerel, 

butterfish, and striped bass were also documented to associate with shoals. It is possible that 

hydrodynamic effects of the shoal features aid in water column feeding by these species. 

Spawning by fishes in the vicinity of sand shoals can be inferred from the presence of eggs and 

early stage larvae. Plankton net samples revealed that anchovy, Atlantic menhaden, Atlantic 

mackerel, and searobins spawn in the vicinity of shoals in the Mid-Atlantic Bight. Shoals may 

also be important as juvenile habitat for species that utilize both inshore estuarine habitats and 

the nearshore shelf as nursery areas. The obligate nature of the association by demersal or 

pelagic fishes with shoals is not known, but it appears that many species rely on shoal features 

as a part of a broader, cross-shelf habitat continuum within which to complete their life cycles. 

Thus, based on the information gathered, sand shoals can certainly be considered EFH and 

efforts should be made to avoid or minimize any adverse effects produced by sand dredging. 
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5.0 SELECTION OF ALTERNATIVE SCENARIOS AND 

SIMULATION OF PHYSICAL PROCESSES 

(Mark R. Byrnes – Applied Coastal Research and Engineering, Inc.) 

5.1 PHYSICAL CONSIDERATIONS 

Shoal and intershoal regions on continental shelves are predominantly composed of fine to 

coarse, well-sorted sand that is highly variable in thickness and areal extent. As shoals migrate 

and sand is reworked, coarse sediment becomes concentrated in areas of greatest wave and 

current energies, typically located along the crests of shoals. Shoal crests often contain very 

little shell material (Swift and Field, 1981; Snedden et al., 1999). Shoal flanks are composed of 

sand and some shell and biogenic material. Intershoal sands contain the most biogenic 

material, but it is never abundant. Wave and current energies prevent mud from being 

deposited in the area. Existing mud and fine sand from underlying deposits are often locally 

exposed on the seafloor. Sand deposits in these areas are usually only a few meters thick and 

have an overall grain size smaller than that of shoals and mainland beaches. 

5.1.1 Specific Shoal Characteristics 

Ocean City is one of the most popular seaside resorts on the east coast. Currently, Fenwick 

Island beaches are part of an engineered system. Regardless of the accumulation of sand on 

the updrift side of the north jetty, frequent beach nourishment is needed to maintain a beach 

along Fenwick Island. Regular sand placement on the beach provides protection against 

storms and preserves the recreational beach. The most recent investigation of borrow sources 

was carried out by USACE (2008). Their findings identify three large candidate shoals 14 to 

18 km offshore of Ocean City as potential sand resources for the maintenance of existing beach 

conditions. This present report evaluates several scenarios for sand removal from shoals, as 

well as possible impacts to each shoal from the different dredging procedures. 

Offshore shoals of particular interest include Weaver, Isle of Wight, and Shoal A (Figure 5.1). 

These three shoals were selected based on several criteria, such as sand quality and volume 

and proximity to the Ocean City beach. These criteria are discussed completely in USACE 

(2008). Other shoals were rejected from consideration for a variety of reasons such as poor 

sand quality, greater distance from the shore, recent dredging activities, existing fish habitats, 

and use in commercial and recreational fishing. Potential borrow sites were evaluated by 

obtaining sand samples collected from vibracores and grab samples. Patterns of sand source 

suitability from these analyses are displayed in Figures 5.2, 5.3, and 5.4. Borrow site maps 

were created by USACE and superimposed on the 2002 bathymetry surface. Ideally, sand 

source grain size should be similar to that of beach sand currently present at the site of beach 

nourishment. Prior to regular beach nourishment that began in 1988, Ocean City beach sand 

had a mean grain size of 0.6 mm (USACE, 1989). After several beach fills using offshore sand, 

mean grain size in 1993 was 0.43 mm (USACE, 2008). 
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Figure 5.1. Bathymetric map of the study area documenting three offshore shoals evaluated for 

potential sand mining for Ocean City, Md., beach nourishment. 
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Figure 5.2. Weaver Shoal sand resource acceptability classification by USACE (2008). 
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Figure 5.3. Isle of Wight Shoal sand resource acceptability classification by USACE (2008). 
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Figure 5.4. Shoal A sand resource acceptability classification by USACE (2008). 
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Weaver Shoal is the most northern shoal to evaluate. The mapped area is approximately 4 km 

long and 2 km wide. Vibracore sample analysis identified two parts of the shoal that contain 

acceptable sand for beach nourishment; the crest and leading edge and the northern half of the 

trailing edge. Isle of Wight Shoal is located 4 km to the southwest of Weaver Shoal. It is 6.5 km 

long and 2 km wide. Sand samples from this feature revealed the southeastern part of the 

trailing edge and the crest of the shoal to contain sand acceptable for beach nourishment. 

Shoal A is located 6.5 km to the southeast of Isle of Wight Shoal. The mapped area is 5 km 

long and 1.5 km wide. Vibracore samples extracted from the shoal identified only the southern 

two-thirds of the trailing edge of the shoal to be compatible with beach sand on Fenwick Island. 

5.1.2 Alternative Excavation Scenarios 

Concerns regarding sand removal effects on physical processes and biological habitat 

prompted USACE (2008) to recommend restrictions regarding sand dredging along shoal crests 

shallower than 30 feet. Based on shoal characteristics defined in USACE (2008), four potential 

dredging scenarios were developed for evaluating changes in physical processes on shoals 

containing acceptable sand deposits for beach nourishment along Fenwick Island. Specific 

numerical excavation scenarios include 

 dredging a hole over a designated area on the shoal; 

 dredging the leading edge of a shoal; 

 dredging the trailing edge of a shoal; and 

 dredging in a striped pattern to facilitate recruitment of benthic invertebrates into dredged 

areas. 

Table 5.1 describes dredging scenario characteristics for each shoal based on USACE beach 

nourishment requirements, and Figure 5.5 shows the locations of each scenario. All potential 

scenarios were located in shoal areas marked “acceptable” by USACE (2008) for dredging. 

Datasets representing numerically excavated bathymetry were created for each scenario. 

Figures 5.6 through 5.13 illustrate three-dimensional renderings of shoal bathymetry after a 

specified amount of sand was removed from each of the shoals. 

Table 5.1. Potential dredging scenario characteristics. 

Shoal Name Sub-Area Removal Type 

Seafloor 

Change 

(see Figure 3.1) 

Excavation 

Depth 

(m) 

Removal 

Volume 

(x106 cu m) 

Crest Hole None 3 1.3 

Weaver Crest Striped None 4 1.7 

Leading edge Slice Deposition 2 1.4 

Crest Hole Minimal 

Deposition 2 1.5 

Crest Striped Minimal 

Deposition 4 1.4 Isle of Wight 

Trailing edge Slice None 2 1.7 

Trailing edge Hole Minimal Erosion 2 1.4 Shoal A Trailing edge Striped Minimal Erosion 3 1.1 

*Striped scenarios include five dredging strips that are 50 m wide and 50 m apart.
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Figure 5.5. Areal extents of modeled dredging scenarios for each shoal. 
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Figure 5.6. Weaver Shoal – hole excavation on shoal crest. 

Figure 5.7. Weaver Shoal – striped area excavation on shoal crest. 
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Figure 5.8. Weaver Shoal – leading edge excavation (slice). 

Figure 5.9. Isle of Wight Shoal – hole excavation on shoal crest. 
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Figure 5.10. Isle of Wight Shoal – striped area excavation on shoal crest. 

Figure 5.11. Isle of Wight Shoal – trailing edge excavation (slice). 
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Figure 5.12. Shoal A – trailing edge excavation (hole). 

Figure 5.13. Shoal A – striped area excavation on trailing edge of shoal. 
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For each of the scenarios listed in Table 5.1, the following output is provided from numerical 

simulations: 

 Sediment deposition/erosion contours; 

 Visual representation of seafloor change; 

 Borrow site infilling for imposed storm conditions; and 

 Circulation pathways (arrows). 

Although one would like to believe that quantities derived from numerical modeling simulations 

are absolute, sediment transport and geomorphology modeling are not advanced enough to 

provide accurate estimates for most derived quantities. Models will always produce numbers, 

but often these numbers are associated with uncertainties of +/- 100%. The greatest benefit of 

using numerical models is their ability to correctly reproduce patterns of flow and sediment 

transport (information) relative to actual measurements (data). For example, pre- and 

post-dredging comparisons will provide an understanding of impacts associated with sand 

extraction, but the absolute magnitude of change (e.g., cm/day) is not nearly as important (or 

reliable) as the percentage of change. A great deal of useful information will be derived from 

numerical modeling results, but limitations must be recognized. 

5.2 NEARSHORE HYDRODYNAMICS, WAVE PROPAGATION, AND 

MORPHOLOGICAL MODELING 

The interaction between waves and currents on the inner continental shelf results in net 

sedimentation patterns recorded on the shelf surface and at the shoreline. Sand shoals and 

intervening swales that formed and evolved on the shelf surface over the past 5,000 years 

create regions of wave energy focusing and divergence, shelf circulation patterns constrained 

by the extent and orientation of these shelf features, and important biological habitat for many 

fish species and benthic communities (Byrnes et al., 2000; USACE, 2008). Extraction of sand 

from specific shoals may be advantageous for beach nourishment purposes, but an evaluation 

of potential physical and biological impacts of suggested sand mining scenarios must be 

evaluated to ensure that adverse environmental impacts are minimized. In the absence of 

years of monitoring measurements to assess potential impacts of sand borrow site excavation, 

numerical modeling procedures developed by the USACE (Buttolph et al., 2006) were applied to 

document potential physical environmental impacts of offshore sand mining. The following 

discussion describes the procedures used and results determined for specific sand extraction 

scenarios constrained by the physical characteristics of sand borrow sites as documented by 

the Baltimore District of the USACE for sand shoals offshore Fenwick Island, Md. (USACE, 

2008). 

5.2.1 Overview of Regional Hydrodynamics 

Tides in the Mid-Atlantic Bight are semi-diurnal, having roughly two high and two low water 

levels each day. Neap tides in the Ocean City area have an amplitude of approximately 1 m, 

while spring tide range increases slightly to about 1.2 m. A 6-day record of tides for NOAA 

Station 8570280 (Ocean City) is shown in Figure 5.14. The diurnal inequality is quite small. 

Primary tidal datums for Station 8570280 (Ocean City Fishing Pier; 1983-2001 Epoch) are 

summarized in Table 5.2. 
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Figure 5.14. Typical semi-diurnal tidal signal from NOAA water level recording Station 8570280 

at the Ocean City Fishing Pier, Md. 

Table 5.2. Reference datums for Ocean City, Md., NOAA Station 8570280. 

Datums Elevation (m) 

Mean High Water (MHW) 0.66 

North American Vertical Datum of 

1988 (NAVD 88) 0.29 

Mean Sea Level (MSL) 0.15 

National Geodetic Vertical Datum 

of 1929 (NGVD) 0.00 

Mean Low Water (MLW) -0.37 

In addition to this forcing from tidal potential, shelf waters along the Mid-Atlantic Bight are 

subject to atmospheric forcing as well, whereby wind stress and pressure gradients can result in 

surface flow, which is independent of tides. Freshwater outflow from the Delaware Bay can 

result in a density-driven current that moves generally to the southwest, passing over the study 

area (Chapman and Beardsley, 1989). This local influx of freshwater can be understood as a 

component of the much larger scale shelf flow, whereby freshwater influx from glacial melt and 

river runoff in southern Greenland generates a buoyancy driven current, which travels more 

than 5,000 km along the Labrador coast, around Newfoundland and the Scotian Shelf, and 

along the Mid-Atlantic Bight, ultimately being entrained in the Gulf Stream offshore North 

Carolina (Beardsley and Winant, 1979). 

Shelf water across the Mid-Atlantic Bight will have a steadier southwest-directed flow during 

autumn and winter months, with fewer instances of reversal compared with summer (Bumpus, 

1973). The average velocity of this net southwesterly flow is roughly 5 cm/s but can reach 

maximum speeds approaching 20 cm/s. During times of extended southerly winds or low 

freshwater runoff, there can be reversals of the surface current, whereby flow is directed to the 

north. 
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Shear stress from wind blowing on the surface of the water can have a strong influence on 

coastal circulation, and in turn, the temperature and salinity profile through the water column. 

During winter months, a low pressure system dominates winds over the Atlantic coast, 

generating relatively strong average winds of about 4 m/s from the west and northwest. As the 

northern hemisphere becomes warmer during late spring, the Bermuda high pressure system 

will strengthen and become the dominant force shaping regional wind patterns in the study area. 

This high pressure system results in average daily winds in the range of 2 m/s, typically from the 

southwest. 

The scope of the present study is far to narrow to include modeling of these large-scale shelf 

processes, but various sources of nontidal forcing and specifically a background flow generally 

directed to the southwest should be acknowledged when considering the results that follow. 

5.2.2 Overview of Regional Wave Conditions 

The interaction of wind with the water surface generates waves. Once wind waves are 

generated, the forces of gravity, and to a lesser extent surface tension, allow waves to travel 

long distances across the sea surface. Waves play a vital role in moving sand along the shoals 

and shaping morphological changes that occur. As such, a proper estimation of wave energy is 

fundamental to estimating the potential effects that offshore dredging will have on the future 

morphology of the shoal complex. 

As waves enter the nearshore zone, variable seafloor morphology causes wave characteristics 

(e.g., height and direction of travel) to change. As waves enter shallow water, their height 

increases (shoaling), and the direction of travel is influenced by variable water depths present 

along the shoal (refraction). There is a limit to how shallow water can get and still have a wave 

remain intact. Eventually wave steepness causes the wave to become unstable and break, 

which dissipates wave energy. Energy also is distributed along a wave crest by a process 

called wave diffraction. Together, wave shoaling, refraction, diffraction, and breaking all 

influence sediment transport and morphology changes observed on the shoal. 

5.2.2.1 Availability of Wave Data 

The USACE Wave Information Study (WIS) has met a critical need for wave information in 

coastal engineering studies since the 1980’s. WIS contains time-series information of 

spectrally-based significant wave height, peak period, peak direction, and wind speed and 

direction produced from a computer hindcast model. The hindcast wave model, WISWAVE 

(Resio and Tracy, 1983), is run using wind data (speed and direction) at selected coastal 

locations around the United States. The model provides wave climate based on local/regional 

wind conditions. Because these data are numerically generated, consistent and long-term wave 

data are available at most coastal locations. 

Selection of the Offshore Boundary Conditions from the WIS Record

Figure 5.15 illustrates the location of WIS stations (yellow markers) that lie within the project 

area. It is desirable for the offshore boundary of the wave model to fall at the same longitude as 

the WIS stations, so that no wave transformation need be performed to apply WIS data to the 

offshore boundary of the model. The inshore line of WIS stations is located too far inshore to be 

of use as boundary conditions, with WIS Station 162 falling exactly on top of Weaver Shoal. To 

ensure that wave refraction and shoaling across the shoals were modeled in detail, the outer 

line of WIS stations was used to select a boundary condition. Station 161 is located offshore 

Weaver and Isle of Wight shoals, while Station 163 is adjacent to Shoal A. A comparison of 

wave roses for WIS Stations 161 and 163 is shown in Figure 5.16. 
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Figure 5.15. WIS stations in the study region are shown with yellow markers. USACE Wave 

Gage MD002 and NDBC Buoy 44009 are shown in green. 
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Figure 5.16. Wave height and energy roses for WIS Stations 161 and 163. 

These plots confirm that a majority of the wave energy offshore of the shoal complex is incident 

from the northeast and the southeast. Moving from north to south, there is a slight increase in 

the percent occurrence of waves from the north, but these differences are quite small. It is 

interesting to note that while the largest waves (orange in the figures) are predominantly 

incident from the north, a majority of all waves are from the southeast. This indicates that under 

typical conditions, waves are incident from the south and southeast, while the largest storm 

events arrive at the shoals from the northeast. 

For the given longitude, it is accurate to say that wave climate immediately offshore the study 

area is spatially consistent. As a result, it was decided to apply the wave model with data from 

a single WIS station rather than impose a spatially varying offshore wave condition. WIS 

WIS 161 

WIS 163 
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Station 161 was chosen to provide the wave data used as a boundary condition for all wave 

runs. 

Verification of WIS Data 

Wave measurements made by NOAA during the 1980’s made verification of WIS results 

possible by comparing the statistics and the distributions of wave heights and periods for 

different time periods (Hubertz et al., 1993). Improvements have been made through 

subsequent modeling efforts to increase the accuracy of WIS results relative to NOAA 

measurements. Second Generation (2G) WIS data, which accounts for weak nonlinear 

wave-wave interaction, equilibrium spectral functions, refraction, shoaling and dissipation, were 

used in the present study. The 2G WIS data provide wave parameter results every hour. A 

detailed comparison between the 2G WIS data, the Third Generation (3G) wave models, WAM 

and WAVEWATCH III, and the relevant National Data Buoy Center (NDBC) stations can be 

found in Tracy and Cialone (2004). The findings from that work are as follows: 

The 2G WIS results are consistent with results from the more complex calculations done in the 

3G models. No one model is the clear winner in these comparisons. The 3G models tend to 

have slightly better directional results. WIS tends to slightly over-predict wave height, and the 

3G models tend to under-predict. WIS captures storms and hurricane events quite well. 

Analysis of peak wave periods showed that all models tested could stand to improve their 

predictions in this regard. 

To supplement the regional scale verification referenced above, current work also compared the 

2G WIS data with an inshore NDBC buoy location nearby the area of interest. WIS Station 161 

and NDBC Buoy 44009 are located approximately 11 km from each other (see Figure 5.15). 

Wave data were recorded at the buoy between 1986 and present. Data from 1990 were chosen 

to compare WIS and NDBC results. The comparison of wave heights for this time period is 

shown in Figure 5.17. Both data sources reported wave heights at 1-hour intervals. 

WIS results reproduce the trend of NDBC-measured data fairly well, but a slight bias in wave 

height is indicated. WIS data appear to slightly over-predict wave heights under storm 

conditions and under-predict during calmer periods. The overall average indicates that WIS 

data under-predict measured wave height by an average of 0.13 m. It should be noted that the 

NDBC buoy is located further offshore than WIS Station 161. The buoy lies in 28 m of water, 

while the location of Station 161 shows a water depth of 21 m. Considering the distance 

between the two locations, wave refraction and breaking could account for much of this 

difference. 

Despite the apparent difference in wave height between WIS Station 161 and NDBC 

Buoy 44009, the availability and continuity of WIS hindcast data make it an attractive choice 

when considering different sources for regional wave conditions. Because the data are 

widespread and continuous, absent accurate field data from very near the site, the 2G WIS data 

are the best option for the development of spectral boundary conditions. 
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Figure 5.17. Wave height comparison between WIS Station 161 and NDBC Buoy 44009 for 

1990. The top panel illustrates a time series of wave heights for each station, 

while the bottom panel shows the difference between WIS and NDBC results as 

WIS prediction - buoy measurement. 

5.2.3 Hydrodynamic Modeling 

ADCIRC – A regional hydrodynamic model for the study area was created for this work using 

the Advanced Circulation Model for Oceanic Coastal and Estuarine Waters, or ADCIRC. 

ADCIRC is a two-dimensional, depth-integrated circulation model (Luettich et al., 1992). The 

model domain is described by a collection of finite elements that give the model excellent 

flexibility to cover large domains and provide the detail required for areas where strong flow 

variations are expected. Computational features of ADCIRC include variable Coriolis forcing, 

wetting and drying, choice of bottom stress model, and detailed user control over model output. 

5.2.3.1 Model Domain 

Figure 5.18 illustrates the model domain for the mid-Atlantic coast. Land boundaries are shown 

in brown, islands are green, and open boundaries are blue. The model was forced at a single 

open boundary running offshore from central New Jersey to North Carolina. The final model 

mesh contains 7,043 nodes and 12,141 elements. 
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Figure 5.18. ADCIRC model domain for the mid-Atlantic coast. The offshore boundary is 

shown in blue, land boundaries are brown, and islands are green. 

5.2.3.2 Boundary Conditions 

ADCIRC allows various forcing options for driving flow in the model, including a time series of 

water-surface elevation, tidal constituents, a time series of flow rates, and wind stress and 

atmospheric pressure. Tidal constituent forcing was applied to open boundaries, and tidal 

potential forcing was applied to the interior of the domain for hydrodynamic simulations. 

Freshwater inflows at Delaware Bay, Chesapeake Bay, and from the Delmarva Peninsula were 

not included in the model due to the 2-D depth averaged solution being unable to model 3-D 

stratified flow conditions. 

The tidal constituent values for the open boundary were extracted from the existing Western 

North Atlantic Tidal Database. This provided constituent data for the M2, S2, N2, K1, O1, Q1, 

P1, K2, M4, and M6 components of the tide. 

Atmospheric pressure changes and local winds have a significant influence on water levels 

within the study area. The relatively shallow offshore shelf means that atmospheric forcing can 

often result in changes in water level that are the same order of magnitude as pure tides. 

However, these atmospheric forcings were not included in the current study. The amount of 
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data required to properly include these aspects into the modeling effort is quite large. Such a 

detailed undertaking is beyond the present scope of this study. 

5.2.3.3 Model Calibration 

The primary purpose for employing the regional hydrodynamic model ADCIRC was to provide a 

time series of water surface elevation as a boundary condition for detailed morphology modeling 

(discussed below). A match of tidal amplitude and phase seaward of Ocean City was deemed 

sufficient for the purposes of describing typical flow patterns along the shelf in the study area. 

The model mesh and bathymetry, as well as the location of the field data station, are shown in 

Figure 5.19. 

Figure 5.19. Detail of the ADCIRC model domain focused on Ocean City, Md. Bathymetry 

contours are shown in color, overlain with model mesh for this region. The NOAA 

tidal recording station used to calibrate the model is shown as a purple dot. 

To limit the influence of the atmospheric signal in field data, the tidal record was searched for a 

period that had no storms and relatively low winds. Spring dates were also avoided to eliminate 

all large freshwater outflow events from the Delaware Bay. Ultimately, the period from 

1-10 October 1991 was chosen to simulate tidal circulation in the hydrodynamic model. 

It would have been preferable to evaluate a more recent time period; however, the only tide 

station currently operational at Ocean City is Station 8570283 at the Coast Guard Station inside 

the inlet. The tide range inside the inlet is roughly 0.3 m smaller than outside and is not 
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indicative of conditions at the study site. Historical tidal data were collected from the fishing pier 

at Ocean City (NOAA Station 8570280); however, this station was abandoned in November 

1991. Because the entire focus of this regional scale hydrodynamic modeling was to recreate 

average tidal conditions used to drive the morphological model, these older data are the best for 

calibration purposes. 

All simulations began on October 1, providing 3 days of run time prior to the period of interest. 

Plots of recorded versus modeled water levels for Ocean City are shown in Figure 5.20. 

Figure 5.20. Comparison of simulated versus measured water levels for NOAA Station 8570280, 

4 to 10 October 1991. 

Figure 5.20 indicates fair agreement between the ADCIRC solution (blue circles) and the 

recorded tide data for NOAA Station 8570280 (black line). Accurate representation of average 

tidal conditions requires an evaluation of two vital tidal features: amplitude and phase of the tide. 

Comparison of measured data and modeled results reveals that both attributes are matched 

well. Model results show slight departures (0.1 to 0.2 m) from measured tidal elevations during 

the first 12 hours and final 36 hours of the time series. This discrepancy is due to nontidal 

forcing recorded in the field data. The most likely process causing nontidal water level changes 

at these times is wind stress. ADCIRC modeling for this project is driven by tidal potential only, 

so any phenomenon impacting water levels due to nontidal forcing does not show up in the 

model solution. 
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5.2.3.4 General Circulation Patterns 

In addition to providing a time series of water surface elevations for calibration at a single point, 

ADCIRC results also provide an overview of flow patterns in the area. Figures 5.21 and 5.22

illustrate current speed contours and direction for typical maximum flooding and ebbing events, 

respectively, near Ocean City Inlet. The locations of Weaver Shoal, Isle of Wight Shoal, and 

Shoal A are outlined as black rectangles for reference. While there are current speeds 

exceeding 1 m/s through the inlet throat, speeds are quite small in open water on the 

continental shelf. Maximum values simulated in the study area are on the order of 5 cm/s. 

Predicted direction of flow is observed to be north/northeast on a flooding tide and 

south/southwest on an ebbing tide. While this hydrodynamic solution is used as a boundary 

condition for morphological modeling discussed below, extremely small flow velocities across 

the study area suggest that waves are the predominant shaping force of shoals over short to 

medium time scales. It is probable that density driven flow to the south or other larger scale 

flows occurring along the shelf could be influencing morphology over time scales longer than the 

ones we have simulated in this study. 

Figure 5.21. Current speed contours and direction vectors for maximum flooding tide at 

Ocean City Inlet, Md., 5 October 1991. Weaver Shoal, Isle of Wight Shoal, 

and Shoal A are framed as black rectangles for reference. 
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Figure 5.22. Current speed contours and direction vectors for maximum ebbing tide at Ocean 

City Inlet, Md., 5 October 1991. Weaver Shoal, Isle of Wight Shoal, and Shoal A 

are framed as black rectangles for reference. 

5.2.4 Wave Modeling 

Nearshore wave heights and directions across Weaver Shoal, Isle of Wight Shoal, and Shoal A 

were estimated using the USACE STeady-state spectral WAVE model (STWAVE) to simulate 

propagation of offshore waves across the area of interest. Offshore wave data available from 

WIS were used to derive input wave conditions for STWAVE. Results of wave modeling were 

used as input for estimating morphology changes within the study area. 

STWAVE – STWAVE v. 4.0 is a steady state, spectral wave transformation model (Smith et al., 

1999). Two-dimensional (frequency and direction versus energy) spectra were used as input to 

the model. STWAVE is able to simulate wave refraction and shoaling induced by changes in 

bathymetry and by wave interactions with currents. The model includes a wave breaking model 

based on water depth and wave steepness. Model output includes significant wave height (Hs), 

peak wave period (Tp), and mean wave direction ( ). 

STWAVE is an efficient program that requires minimal computing resources to run well. The 

model is implemented using a finite-difference scheme on a regular Cartesian grid (grid 

increments in the x and y directions are equal). During a model run, the solution is computed 

starting from the offshore open boundary and is propagated onshore in a single pass of the 

model domain. As such, STWAVE can propagate waves only in directions within the 87.5 half 

plane. A benefit of using this single pass approach is that it uses minimal computer memory 
MMS Study 2010-010 

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because the only memory-resident spectral data are for two grid columns. Accordingly, 

changing wave spectra across each grid column are computed using information from the 

previous grid column only. 

STWAVE is based on a form of the wave action balance equation. The wave action density 

spectrum, which includes the effects of currents, is conserved along wave rays. In the absence 

of currents, wave rays correspond to wave orthogonals, and the action density spectrum is 

equivalent to the wave energy density spectrum. A diagram showing the relationship between 

wave orthogonal, wave ray, and current directions is shown in Figure 5.23. The governing 

equation of wave transformation, using the action balance spectrum, in tensor notation is written 

as follows (Smith et al., 1999): 

    





r r

a ga

i

i ga

C C E S

x

C

 

cos( ) (1) 

where 

E = E(f,) wave energy density spectrum; 

S = energy source and sink terms (e.g., white capping, breaking, wind input); 

 = wave orthogonal direction; 

 = wave ray direction (direction of energy propagation); 

r = relative angular frequency (2fr); and 

Ca = absolute wave celerity; and 

Cga = absolute group celerity. 

The breaking model in STWAVE is based on a form of the Miche criterion as discussed by 

Battjes and Janssen (1978). It sets a maximum limit on the zero-moment wave height (Hmo), the 

wave height based on the distribution of energy in the wave spectrum. The formulation of this 

model is 

Hmo(max) = 0.1L tanh (kd) (2) 

where L is the wavelength, k is the wave number (k = 2/L), and d is the depth at the point 

where the breaking limit is being evaluated. This equation is used together with a simpler 

breaking model, which was used alone in earlier versions of STWAVE, where the maximum Hmo 

wave height is always expressed as a constant ratio of water depth. 

Hmo(max) = 0.64 d (3) 

An advantage of using Equation 2 over Equation 3 is that it accounts for increased wave 

breaking resulting from wave steepening caused by wave-current interactions. Once model 

wave heights exceed Hmo(max), STWAVE uses a simple method to reduce the energy spectrum 

to set the value of Hmo = Hmo(max). Energy at each frequency and direction is reduced by the 

same percentage. As a result, nonlinear transfers of energy to high frequencies during breaking 

are not included in STWAVE. 
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Figure 5.23. Wave and current vectors used in STWAVE. Subscript a denotes values in the 

absolute frame of reference, and subscript r denotes values in the relative frame of 

reference (with currents). 

5.2.4.1 Model Domain and Bathymetry 

Wave modeling consisted of a single model grid (100-m x 100-m grid cells) that included all 

three shoals of interest (Table 5.3). The limits of the grid (Figure 5.24) were chosen so that the 

offshore boundary coincided with the longitude for WIS Station 161, the station chosen to supply 

boundary conditions for wave modeling runs. Lateral extents of the coarse grid were selected 

far enough away from the shoal to ensure that the model domain was free from any edge 

effects present in the solution. 

Figure 5.24. STWAVE bathymetry and model grid domain. The location of WIS Station 161 is 

shown as a circle on the eastern boundary. 
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Table 5.3. Dimensions for the wave grid. 

Cell Size Grid Dimensions Number of Water Cells Typical Run Time 

(19 Wave Cases) 

100 m x 100 m 233 rows x 144 columns 25,439 ~28 minutes 

Bathymetry data were gathered from several sources and combined to provide a single data set 

covering the entire study area. Offshore bathymetry is composed of data collected in the 1970’s 

and digitized from National Ocean Service (NOS) hydrographic surveys (H-sheets). High 

density survey data of each shoal were provided by the USACE Baltimore District to supplement 

the existing NOS data set. These survey data were collected in November 2002 as part of an 

offshore sand resources study of the Atlantic Coast of Maryland (USACE, 2008). 

5.2.4.2 Boundary Conditions 

STWAVE input spectra were developed using a numerical routine that recreates a 2-D spectrum 

from whichever individual wave condition in the WIS record is requested. The program 

computes the frequency and directional spread of a wave energy spectrum based on significant 

wave parameters (i.e., wave height, peak period, and peak direction) and wind speed (Goda, 

1985). The frequency spectrum S(f) is computed using the relationship 

  4

1/ 3

5

1/ 3 1/ 3

2

1/ 3 ( ) 0.257 ( ) exp 1.03( )   S f  H T T f  T f (4) 

known as the Bretschneider-Mitsuyasu spectrum, where H1/3 is the significant wave height, f is 

the discrete frequency where S(f) is evaluated, and T1/3 is the significant period, estimated from 

the peak wave frequency (fp) by 

  p T 1/ 1.05f 1/ 3  (5) 

To compute the two-dimensional energy spectrum, a directional spreading function G(f,) must 

be applied to the frequency spectrum such that 

S(f, )  S(f )G(f, ) (6) 

In this method, the directional spreading function is computed using the relationship 





 



  2 ( , ) cos2   s Go G f (7) 

where s is a spreading parameter related to wind speed and frequency,  is the azimuth angle 

relative to the principal direction of wave travel, and Go is a constant dependent on  and s. The 

spreading parameter s is evaluated using the expression 
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







 

   

p p

p p

s f f f f

s f f f f

s

( / ) :

( / ) :

2.5

max

5

max (8) 

where 2.5

max 11.5(2 / )

 s  fpU g . Wind speed U is therefore used to control the directional 

spread of the spectrum by increasing the directional spread with increasing wind speed (g is the 

acceleration of gravity). Finally, the constant Go is computed by evaluating the integral. 

1

max 2

min 2

cos

















 



 



  





  G d s

o (9) 

The result is a wave energy spectrum that is based on parameters from the WIS record, and 

that distributes spectral energy based on wave peak frequency and wind speed. An example of 

a 2-D spectrum generated by this method is presented in Figure 5.25. 

Figure 5.25. STWAVE input spectrum developed using WIS 20-year hindcast data with the 

Goda (1985) method of computing frequency and direction spectrum. Plots show 

a) frequency distribution of energy at peak direction, b) directional distribution of 

energy at peak frequency, and c) surface plot of energy spectrum (Hmo = 0.9 m, 

θmean = 130°). 

5.2.4.3 Nearshore Wave Prediction Versus Gage Measurements 

Before proceeding with model simulations under various dredging scenarios, wave model 

simulations were compared with USACE wave gage measurements collected off Ocean City in 

9-m water depth (USACE Gage MD002; Figure 5.15). The purpose of this effort was to test the 

reliability of STWAVE at predicting wave propagation in the project area. Because most wave 

energy in this area is from the northeast, WIS and USACE wave gage records were examined 

to identify a storm event from the northeast. A storm in October 1997 was chosen where the 

inshore wave heights exceeded 2 m and the wind was from the northeast. For this same time 

period, WIS results from Station 161 were used as input for STWAVE, and model results were 

compared to gage data. 

It is unrealistic to expect an exact match of wave conditions at the wave gage location because 

input from WIS is itself modeled data. But with that caveat, there is still value in comparing 

STWAVE results to field data as plotted in Figure 5.26. Simulated (STWAVE; triangles) and 

a) b) c) 
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measured (MD002; squares) wave heights at the location of the USACE nearshore wave gage 

were compared to assess the reliability of propagating simulated WIS results across the study 

area. Figure 5.26 illustrates wave height differences (x) taken as the absolute value of the 

difference between the recorded wave height and the STWAVE prediction at the gage location. 

Figure 5.26. Wave height values from USACE nearshore gage MD002 during the 1997 storm. 

STWAVE results using WIS Station 161 input and wave measurements for the 

nearshore gage are plotted for comparison. The difference between simulated 

wave heights and measurements documents maximum difference during the peak 

of the storm. 

The overall signature of storm intensity is recreated well, indicating that WIS data generally 

capture the timing of a storm event. For the first 24 hours, little difference exists between wave 

height simulations and gage measurements. This close agreement suggests that the wave 

model is accurately simulating wave propagation across the ridges and swales within the model 

grid. STWAVE results indicate a noticeable departure from field data during the height of the 

storm. It is difficult to say if this is a result of model uncertainty or the trend of WIS data 

over-predicting wave heights at the peak of storms, as was discussed above when comparing 

WIS data to NDBC Buoy 44009. 

Following the peak of the storm, agreement between model results and measured wave heights 

becomes more reliable. Over the course of the 3-day storm, STWAVE results in the nearshore 

echo of the trend seen in field data and demonstrate an adequate agreement with specific wave 

heights from the wave gage. 
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Throughout the storm period, wave direction appears biased 5o to 10o to the north of field 

measurements. This discrepancy is likely the result of resolution deficiency in nearshore 

bathymetry and possibly coarseness of the wave grid. During model grid construction, detailed 

bathymetry was used for shoals in the study area, but in the nearshore, bathymetric data were 

relatively sparse. Without detailed representation of shoals closer to shore, and without 

increased grid spacing, wave modeling is not able to accurately recreate refraction and shoaling 

closer to shore. As such, differences between the model results and the field observations are 

recorded. 

5.2.4.4 Wave Model Results 

Overall, the study is focused well offshore of the region where the wave gage was deployed, 

and the discussion that follows focuses on wave model results for northeast and easterly storms 

in the area of Weaver Shoal, Isle of Wight Shoal, and Shoal A. Figure 5.27 illustrates 

bathymetry within the study area over which waves were propagated to provide a reference for 

evaluating wave modeling results. 

Figure 5.27. Wave model bathymetry for the study area. The 12-m contour is outlined on each 

shoal as a reference. 
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Figure 5.28 shows one time-step of the 3-day storm event for the (a) northeast case and 

(b) east case. For the northeast case, incident wave heights are on the order of 5 m. As waves 

propagate shoreward from the east, uniform wave heights and directions observed at the 

boundary are replaced by varying wave heights and directions as wave energy is redistributed 

by interacting with shoal bathymetry. Between Fenwick, Weaver, and Isle of Wight shoals, 

there is a repeated pattern of increased wave heights in the area of shoals and a decrease in 

wave height at low regions between the shoals. Waves encountering shoals from deep water 

will experience shoaling, with an accompanying increase in wave height and possibly breaking. 

Furthermore, wave energy is focused or dispersed due to refraction over the shoals. This wave 

focusing is especially apparent in Figure 5.28(a), where waves from the northeast are traveling 

parallel to bathymetric features oriented to the northeast. As waves approach the shoals, they 

are influenced by bathymetry long before they encounter the shoal crest (denoted by the 12-m 

depth contour). Weaver and Isle of Wight shoals have regions of shallow bathymetry 

immediately to the northeast of their crests (see Figure 5.27). As waves from the northeast 

approach shoal crests, wave vectors illustrate energy being focused on the north side of each 

shoal. Accompanying this refraction pattern and subsequent increase in wave height is a 

decrease in wave height immediately to the south of the shoal. 

Figure 5.28. Wave model results in Hour 40 of the storms with waves incident from a) the 

northeast and b) the east. Note that the color scale range is different for the two 

wave conditions. 

Figure 5.28(b) illustrates wave results for a single time during the storm from the east. For this 

particular image, waves are incident slightly south of east with wave heights at the boundary of 

2.6 m. It is immediately apparent that the model results for this run are significantly different 

from those of the northeast case. The most striking difference is the relative uniformity of wave 

height across the entire domain for this wave condition. There are none of the areas of banded 

wave heights that were seen in the previous scenario. There are two primary reasons for this 

difference. The first is that the wave heights in this scenario are relatively small and less 

a b 
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affected by shoal bathymetry. Water depths across the shallowest part of Isle of Wight Shoal 

are on the order of 7 m, and these 2.5-m waves pass across the shoals relatively unchanged. 

The second reason for the difference in wave results is that waves are incident from a direction 

perpendicular to shoal orientation. From this direction, bathymetry changes are relatively sharp, 

and there is an expected increase in wave heights across the crests of the shoals. Some 

refraction is evident as the waves pass over the crests of the shoals, but without long stretches 

where waves are running parallel to a ridge and trough, there is not the opportunity for the 

strong wave focusing observed in the northeast storm. 

5.2.5 Nearshore Sedimentation and Borrow Site Infilling 

The primary purpose for wave transformation modeling in this study is to predict wave shear 

stress and momentum so morphology change calculations can be performed with input from 

waves and currents under imposed storm conditions. WIS information was examined to identify 

the largest storm event from the northeast between 1980 and 1999 as one wave condition for 

morphologic change modeling. An event from mid-October 1984 was chosen, where waves at 

WIS 161 were from the northeast and exceeded 6 m at the peak of the storm. WIS information 

was also examined to find a large storm from the east to observe the impact of wave direction 

on morphologic change simulations. The event chosen took place in late September 1992, 

when wave heights briefly exceeded 5 m. In both cases, wave information was input from the 

record every 4 hours for 72 hours. Including an initial wave case at time zero, this approach 

yielded 19 wave height/direction pairings for each scenario. 

By combining wave and hydrodynamic modeling results with appropriate nearshore sediment 

transport formulae, seafloor change simulations were conducted to predict natural and 

dredging-induced responses to incident coastal processes. It was anticipated that numerical 

simulations would shed light on the most likely pathways for sediment movement, as well as 

provide some idea of the relative magnitude of change under differing wave and dredging 

conditions. The response of each shoal to various dredging scenarios is of primary interest. 

This component of the modeling effort was concerned with morphology response of offshore 

shoals to various sand mining scenarios. 

CMS-M2D – CMS-M2D is a 2-D, depth-integrated, finite-difference hydrodynamic model. It also 

has the option of including morphology change estimates through the use of a sediment 

continuity equation for updating changes in bathymetry. Full coupling with an external wave 

model (STWAVE in this case) is possible, with the wave model providing radiation and shear 

stresses to CMS-M2D. In return, the hydrodynamic and morphology changes are passed back 

to the wave model. 

5.2.5.1 Model Domain 

Limits of the model domain were chosen to encompass shoals and adjacent environments to 

provide a well-determined boundary for hydrodynamics. It is best practice for the hydrodynamic 

grid to lie completely within the wave grid for the coupled STWAVE and CMS-M2D simulations. 

This prevents the need for CMS-M2D to extrapolate radiation and shear stresses past the 

boundaries of the wave model solution. The final CMS-M2D model domain was developed with 

these concerns in mind (Figure 5.29). Many attempts were made to develop a model solution 

using four ocean boundaries to reduce computation time. Ultimately, this approach was 

abandoned in favor of the larger domain, which was widened to include a shoreline boundary on 

the west. 
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Figure 5.29. CMS-M2D model domain is marked by the brown rectangle. The navy rectangle 

illustrates the limits of the STWAVE model grid for comparison. 

One benefit of the CMS-M2D model is its ability to incorporate variable cell sizes, so the model 

can provide fine resolution across the shoals where greatest change is expected, and grid cells 

away from the shoals have a wider spacing. This flexibility allows for optimization between 

proper grid resolution and run time efficiency. Grid cells in the CMS-M2D model vary between 

60-m spacing across much of the shoals, expanding to 250-m spacing at the corners of the 

domain. Figure 5.30 shows the finished grid with variable spacing. 
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Figure 5.30. CMS-M2D model grid showing the variable cell spacing. 

5.2.5.2 Dredging Scenarios 

As discussed in Section 5.1.2, four scenarios were chosen to examine sediment transport 

patterns in response to incident coastal processes, including baseline, dredging the crest of a 

shoal to a specified bathymetry contour, dredging the leading edge of the shoal, and dredging a 

striped pattern over the shoal crest to facilitate recruitment of benthic invertebrates. For each 

scenario, the lateral extents of dredging were determined based on the location of desirable 

sand on each shoal (USACE, 2008). If a specific scenario would call for dredging in an area 

with poor sand quality, this scenario was not evaluated for the shoal in question. For example, 

sand on the crest of Shoal A was not deemed acceptable by the USACE (2008), so dredging on 

the shoal crest (trailing edge) was not imposed within the model domain for this site. Table 5.4

illustrates the final configuration of modeling runs within the project area. 
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Table 5.4. Selected dredging scenarios. 

Scenarios Weaver Shoal Isle of Wight 

Shoal Shoal A 

Baseline (No Action) x x x 

Crest Polygon x x x 

Leading/Trailing Edge x x --- 

Striped Pattern x x x 

x = simulated scenario; --- = no simulated extraction 

5.2.5.3 Boundary Conditions 

The hydrodynamic solution from the ADCIRC simulation was used to provide a time series of 

water levels along each open boundary. The 3-day period from 6-9 October 1991 was used to 

drive hydrodynamics in the CMS-M2D simulations. This period was selected because it 

represented a typical tidal range (~1 m) during a time of low freshwater runoff. This simulation 

served to recreate average tidal conditions. 

For each of the scenarios in Table 5.4, two separate wave conditions were imposed. The first 

was a severe storm from the northeast with significant wave heights approaching 6 m at WIS 

Station 161. The second wave condition was an easterly storm with wave heights approaching 

5 m at WIS Station 161. As modeling scenarios were being finalized, a storm from the 

southeast with maximum wave heights of 3 m was also evaluated. The initial results indicated 

these smaller wave heights were insufficient to produce any significant morphology change on 

the shoals. As a result, the southeast storm condition was replaced by the more energetic 

easterly condition. 

5.2.5.4 Model Setup 

With boundary conditions assigned, the remainder of model setup was concerned with properly 

choosing variables relevant to morphology predictions, as well as the coupling between 

STWAVE and CMS-M2D. A summary of model variables is provided in Table 5.5. The 

advection-diffusion transport scheme was chosen because it is the only formulation that 

accounts for suspended load and bed load transport separately. The role of suspended 

sediment is especially important in these dredging scenarios, because it is primarily responsible 

for infilling of the interior of dredged areas. Other “total load” transport formulations available in 

CMS-M2D would not be as robust in this regard. 

Table 5.5. Values for CMS-M2D model variables. 

Variable Setting 

Hydrodynamic time step 3 seconds 

Transport Rate time step 30 seconds 

Morphologic time step 30 minutes 

Sediment transport formulation Advection-diffusion 

Mean grain size 0.4 mm 

Interface with STWAVE every 4 hours 
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5.2.5.5 Morphological Model Results 

While morphological modeling does provide specific values of bottom change for individual 

storm conditions, without data to calibrate these results, quantitative estimates of change should 

be treated with caution. The true value of morphological modeling is not in the specific values of 

bottom change, but rather how the results differ from each other as starting bathymetry and 

wave conditions are varied. It is relative change between scenarios that is most reliable and not 

the absolute magnitude of specific change calculations. 

Baseline (No Action) 

Initial model simulations examined predicted change under storm conditions for existing 

bathymetry, with no dredging performed. This scenario is labeled Baseline in Table 5.4. 

Documenting results from these runs provided a basis for comparing modeled dredging 

scenarios. Although Fenwick Shoal is shown at the northern extent of the model domain, the 

shoal is not included in any of the dredging scenarios. 

Figure 5.31(a) illustrates initial bathymetry for the shoal complex. Figure 5.31(b) documents 

bottom change predicted under northeast storm conditions. As expected, a general trend of 

erosion (yellow and red colors) is illustrated along northern portions of the shoal with deposition 

(green and blue colors) to the south. Because wave energy is incident from the northeast, sand 

is suspended along the northern section of the shoal crest and pushed to the leading edge, 

where is it deposited. This pattern is seen most clearly at Isle of Wight Shoal, where there is a 

clear area of erosion on the northern half of the crest and then subsequent deposition in three 

bars along the southern face of the shoal. A similar trend is seen on Shoal A, with distinct 

patterns of change on both the smaller subshoals. Weaver Shoal indicates deposition along the 

leading edge but no clear area of erosion, suggesting that the sediment depositing along the 

front edge is an accumulation of sand from a wider area of the shoal to the north, as opposed to 

a specific location. 

It is interesting to note the relative magnitude of change observed between the shoals. Isle of 

Wight (and Fenwick Shoal at the far north) exhibit(s) well-defined areas of change, as should be 

expected from the shallowest areas of the study site. Both have depths of ~7 m along the shoal 

crest. Weaver Shoal is situated between these shoals, reaching a minimum depth of ~9 m at 

the crest. Sheltered to some extent by Fenwick Shoal and the wide expanse of deeper shoals 

to the north, relatively little seafloor change is predicted. Shoal A, at the southern extent of the 

study area, is relatively isolated, and despite being the deepest of the shoals (having a minimum 

crest depth of ~11 m), change patterns are still observed. 

Figure 5.31(c) reveals that with a significant storm from the east, there is relatively little bottom 

change predicted. It should be noted that while change predicted for the northeast storm shown 

in (b) is on the order of 0.1 m, change from the easterly event in (c) is on the order of 0.01 m as 

denoted by the color scale bars. Although there is an order of magnitude difference in bottom 

change predictions, these results are still useful to illustrate how change patterns differ from the 

northeast wave case. They also provide reference for evaluating change predicted for the 

dredging scenarios. 
110

.Figure 5.31. CMS-M2D model results for existing conditions showing a) bathymetry at the start of the model run

calculated for the northeasterly storm condition, and c) bottom change for the easterly storm condiall plots show the 12-m depth contour for Weaver, Isle of Wight, and Shoal A. 
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Isle of Wight Shoal provides the strongest signature of change with erosion along the eastern 

face of the shoal where wave energy first impacts the shoal, and deposition on the westerly face 

as water depths decrease. Weaver Shoal displays a small area of erosion on the easterly face 

but no corresponding area of deposition, suggesting that sand is distributed widely across the 

rest of the feature. Shoal A shows no appreciable bottom change at all, indicating that shoal 

depth limits the influence of these wave conditions. 

Figure 5.32 illustrates average transport vectors for the Baseline scenario during the northeast 

storm condition. This plot is a snapshot of a single time step extracted from the 3-day 

simulation. The figure illustrates magnitude (color) and direction (arrow) of average sediment 

transport (bed load and suspended load) calculated by CMS-M2D. There is a clear trend of 

transport from the northeast to the southwest for each of the shoals, which matches the 

direction of wave propagation. This trend in transport serves as further confirmation that sand 

transport and shoal morphology on short time scales is dominated by wave forcing. Sand 

transport across Isle of Wight Shoal (and Fenwick Shoal) is greater than that observed at 

Weaver Shoal and Shoal A, a trend consistent with morphology change results. For all shoals, 

an increase in transport rate is documented as waves approach the shoal crest. Maximum 

transport is attained across the crest, and magnitudes decrease shoreward of the shoals. The 

same general trend was documented for each of the following dredging scenarios, regardless of 

specific geometric characteristics for each scenario. As a result, additional transport plots for 

each scenario are not included below. 

Crest Polygon 

The shoal crest dredging scenario consisted of a single 

polygon dredged from each of the shoals. The crests of 

Weaver and Isle of Wight shoals were dredged, while a 

section along the northwest face of Shoal A was dredged 

(Figure 5.33[a]). Sediment sampled at the crest of Shoal A 

was eliminated from consideration by USACE (2008), but 

sand on the trailing edge to the northwest was deemed 

acceptable. 

Figure 5.33 indicates that during a strong storm from the 

northeast, Weaver Shoal will experience sand transport 

from the northeast and deposition adjacent to the edge of 

the “dredged” area. The northwest margin of the 

excavation site also illustrates some deposition. In total, 

9,000 m3

 of sand were deposited within the boundaries of 

the dredging area. The absence of deposition further into 

the center of the dredged area can be understood as an 

absence of sand transport into the depression. All sand 

moved from the northeast face of the shoal is deposited 

immediately upon transport into the “dredged” region of the 

shoal. It should be expected that over time, the center of 

the dredged area would start to fill, with the southern extent 

of the “dredged” area being the last region to fill. There is 

still some deposition along the leading edge of the shoal, as 

was observed under the Baseline scenario discussed 

above. 

Figure 5.32. CMS-M2D average 

transport vectors for 

the Baseline scenario. 
112

Figure 5.33. CMS-M2D model results for numerically excavated sand from each of the shoals for the Crest Poly

showing a) bathymetry at the start of model run, b) the bottom change calculated for the northeastand c) bottom change from the easterly storm condition. For reference, all plots show the 12-m deWeaver, Isle of Wight, and Shoal A. The extents of the “dredging” areas are outlined in black. 
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In contrast to Weaver Shoal, there is significantly more sand eroded from the northeast face of 

Isle of Wight Shoal, and subsequently, a larger area of sediment deposition is observed within 

the “dredged” area. The same general pattern is observed where there is greater infilling at the 

northeast extent of the “dredged” region, but the magnitude and spatial extent of deposition is 

much larger. Total sediment deposition within the impacted area is about 40,000 m3

. 

Shoal A, to the south, shows little change in morphology compared with the Baseline scenario. 

The “dredged” region along the northwest face of the shoal exhibits no observable infilling, while 

similar modest changes are observed at the shoal crest. If there is any sand moving along 

Shoal A, it is not coming into contact with the dredged region, and hence, there is no deposition. 

Aside from the very top of the shoal crest, again we see that water depths are too deep to result 

in significant sediment mobilization along the trailing edge of the shoal. 

Figure 5.33(c) shows virtually no morphology change for storm conditions approaching from the 

east. Water depths are too great at Weaver Shoal and Shoal A for any appreciable sediment 

movement, and Isle of Wight Shoal records only the smallest amount of change. 

Leading/Trailing Edge 

The second numerical excavation scenario consisted of dredging the leading edge of Weaver 

Shoal and the trailing edge of Isle of Wight Shoal. There is no “dredging” depicted on Shoal A 

for this scenario. 

Under a significant storm from the northeast, the numerically excavated region on the leading 

edge of Weaver Shoal illustrates infilling (Figure 5.34). Greatest deposition was observed 

along the southwest face of the shoal, with a thin band of accretion also appearing along the 

southeast margin of the “dredged” area. This pattern is similar to that observed in other 

excavation scenarios, with the exception being that most deposition is occurring closer to the 

crest of the shoal as a result of the dredged region extending toward the crest. Approximately 

26,000 m3

 of sand are deposited within the “dredged” area on the front of the shoal. 

At Isle of Wight Shoal, the northwest face of the shoal contained quality beach sand that was 

numerically removed to evaluate sediment transport changes resulting from sand dredging. 

There are small areas of accretion along the edges of the dredged area closest to the crest. 

However, most of the sediment moved from the crest is deposited along the southeast face of 

the shoal. There is little forcing during this event to move suspended sediment over the crest to 

the north and into the “dredged” area. Only 8,000 m3

 of sand returned to the “dredged” area 

during the simulation. 

Again, for the case of the easterly storm shown in Figure 5.34(c), there is no significant change 

in shoal morphology. The small amount of change illustrated for Isle of Wight Shoal indicates 

sand moving from east to west across the crest of the shoal, perhaps settling partly within the 

eastern edge of the “dredged” region. 

Striped Pattern 

The third numerical excavation scenario consisted of trenches dredged across the same regions 

of the shoal as the Crest Polygon scenario. The crests of Weaver and Isle of Wight shoals and 

the northwest face of Shoal A were “dredged” in a striped pattern. The striping consisted of 

swaths of sand numerically excavated 3-m deep, with a spacing of 50 m over a distance of 

about 1 to 2 km. 
114

Figure 5.34. CMS-M2D model results for numerically excavated sand from the leading edge of Weaver Shoal a

Isle of Wight Shoal, showing a) bathymetry at the start of model run, b) bottom change calculated fstorm condition, and c) bottom change from the easterly storm condition. For reference, all plots scontour for Weaver, Isle of Wight, and Shoal A. The extents of the “dredging” areas are outlined in 
MMS Study 2010-010

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Figure 5.35 illustrates morphology change for the striped excavation scenario on shoal crests. 

For each of the shoals, excavated troughs began to fill while the undisturbed regions between 

the troughs were eroding. For Weaver and Isle of Wight shoals, there is a similar pattern of 

erosion and deposition to that identified for Crest Polygon “dredging,” where greatest deposition 

occurs from northeast to southwest. Furthermore, there is persistent deposition throughout the 

entire “dredged” area. Deposition in the center and southern portions of the excavated area is a 

result of redistribution of sand from undisturbed areas between the troughs into adjacent low 

areas. This pattern is seen again within the area “dredged” in Shoal A, although the lowest 

areas of striping along the northwest face remain unchanged. 

For the Striped Pattern scenario, volume loss (from the eroding ridges) and volume gain 

(deposition in troughs) is measured for each shoal. At Weaver Shoal, troughs gained 34,000 m3

of sand while the crests lost 24,000 m3

, resulting in a net gain within the dredged area of 

10,000 m3

. This quantity is similar to that gained for the Crest Polygon “dredging” scenario, but 

sand deposition associated with the Striped Pattern scenario is spread evenly across the 

impacted area rather than concentrated at the northeast edge of the “dredged” polygon. 

Similarly, Isle of Wight Shoal experiences a gain of about 128,500 m3

 of sand accompanied by a 

loss of 76,000 m3

, resulting in a net gain of 52,500 m3 of sand within the excavated area. Sand 

changes associated with Shoal A indicate a gain of about 14,000 m3

 and a loss of 21,000 m3, 

resulting in a net loss of 7,000 m3

 of sand. The most likely reason for net loss of sand after 

“dredging” Shoal A relates to the location of sand excavation on the trailing edge of the shoal. 

Primary forcing is from the northeast, so a majority of mobilized sand is not supplying sand to 

the “dredged” area. Most change indicates erosion on the crest and deposition along the 

leading edge of the shoal to the south. As a result, there is a net loss of sand in the excavated 

region as sand is transported south to the leading edge of the shoal rather than toward the 

depressions left by “dredging.” 

As Figure 5.35(c) illustrates, there is very little sediment movement of significance under storm 

conditions from the east. Morphology change on Isle of Wight Shoal and Shoal A are nearly 

identical to that identified under previous scenarios. Weaver Shoal shows a minor amount of 

accretion within troughs at the southwest edge of “dredging.” 

5.2.6 Discussion 

Simulating morphologic changes associated with potential sand mining scenarios on shoals 

offshore Fenwick Island, Maryland, was accomplished using three interrelated numerical models 

to develop an understanding of tidal hydrodynamics, wave processes, and sediment transport 

patterns. More specifically, model coupling was completed to assess the morphologic response 

of offshore sand shoals to various “dredging” scenarios in support of future beach nourishment 

requirements. 

Tidal hydrodynamics for the continental shelf and nearshore areas offshore the Delmarva 

Peninsula were modeled using ADCIRC. Model prediction of tidal amplitude and phase 

offshore Ocean City Inlet was compared with measured data from a NOAA tide gage and found 

to match well. Average tidal flow velocities observed in the study area are on the order of 

0.05 m/s. The direction of flow is observed to be north/northeast on a flooding tide and 

south/southwest on the ebbing tide. A time series of water surface elevation was taken from 

these results and used as the hydrodynamic boundary conditions for CMS-M2D modeling. 
116

Figure 5.35. CMS-M2D model results for dredging a striped pattern from each shoal showing a) bathymetry at t

b) the bottom change calculated for the northeast storm condition, and c) bottom change from the condition. For reference, all plots show the 12-m depth contour for Weaver, Isle of Wight, and Shothe dredging areas are also outlined. 
MMS Study 2010-010

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With such small tidal velocities so far offshore, incident wave energy played a primary role in 

sediment movement and morphology change at the offshore shoals. To investigate details of 

wave transformation throughout the study area, an STWAVE model was developed for the 

region. Hindcast wave data from WIS Station 161 were used as input to the wave model. A 

large storm with waves from the northeast (Hmo = 6 m) was modeled, along with a storm from 

the east (Hmo = 5 m), to observe differences that incident wave direction has on results. Model 

results from the northeast storm condition indicate that waves incident from this direction 

undergo strong wave focusing across the offshore shoals. Wave focusing is primarily the result 

of waves traveling parallel to bathymetric features, providing ample time for waves to refract as 

they propagate landward. This phenomenon results in a banded wave energy pattern where 

there are regions of increased wave height along the shoal crests. Areas of increased wave 

heights are flanked by regions of decreased wave heights, typically along the southern side of 

shoal crests and in deeper water lying between shoals. Waves incident from the east propagate 

perpendicular to shoal orientation, and hence, a more typical wave pattern is observed. There 

is minor wave focusing and an increase in wave shoaling across the crests of the shoals. 

While providing insight into hydrodynamics throughout the study area, the primary purpose for 

ADCIRC and STWAVE modeling was to provide forcing for the CMS-M2D model so that shoal 

morphology change could be examined. Bathymetric change at and adjacent to the shoals in 

response to various “dredging” geometries was of particular interest. 

In addition to a Baseline scenario for each of the shoals, three dredging geometries for Weaver 

and Isle of Wight shoals were simulated, along with two dredging scenarios at Shoal A. Each of 

these geometries was evaluated under a 3-day storm from the northeast and a 3-day storm 

from the east (Table 5.6). Results from the Baseline scenario provided insight to the current 

trends in shoal morphology and migration. Simulations indicate dominant sand transport from 

northeast to southwest and south, where sand is eroded from shoal crests and deposited on the 

leading edge of the shoal. This pattern is seen on each of the three shoals in the study area, 

with Isle of Wight Shoal illustrating greatest change. 

Shoal response to imposed dredging scenarios revealed a trend of infilling where “dredging” 

was performed on areas of the shoal where sediment deposition was indicated under the 

Baseline scenario. The Crest Polygon scenario examined for Weaver Shoal is a good example, 

where a simple polygon dredged on the shoal crest did not illustrate much infilling. This result is 

consistent with sand transport patterns for the Baseline scenario, which showed little deposition 

on the shoal crest. In contrast, the Baseline scenario showed the leading edge of Weaver 

Shoal to be a natural depocenter, and when the leading edge of Weaver Shoal was “dredged,” 

sand was deposited in the excavated area. 

Modeling results serve to illustrate that a dredged portion of a shoal will not simply fill because 

there is a depression present (Table 5.6). If dredging is performed on a portion of a shoal that 

is not active under baseline conditions, there will be a lack of sand availability to replenish sand 

removed during borrow site excavation. Imposed storm conditions will not be effective at 

mobilizing significant amounts of sand in the excavated area, and large-scale shelf processes 

and major storm events may be the only mechanisms by which “dredged” areas will be filled. 

The corollary to this is that material removed from active areas of a shoal will be replenished 

more quickly by normal wave conditions at the site. Shallow shoal crests, like Isle of Wight 

Shoal, and the leading edge of all three shoals are noted as the active areas of 

erosion/deposition. These active transport and deposition areas will recover to original 

conditions more rapidly than inactive portions of shoals. 
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Table 5.6. Summary of Numerical Modeling Results. 

Dredging 

Scenario 

Storm 

Condition 

Weaver Shoal (~9 

m deep at 

shallowest point) 

Isle of Wight Shoal

(~7 m deep at 

shallowest point) 

Shoal A (~11 m 

deep at shallowest 

point) 

3-day storm 

from the 

northeast 

Minor deposition on 

leading margin of the 

shoal. 

Prominent zone of 

erosion on the north 

side of the shoal is 

associated with 

downdrift deposition 

along the leading 

margin of the shoal. 

Moderate zone of 

erosion on the north 

side of the shoal is 

associated with 

downdrift deposition 

along the leading 

margin of the shoal. 

Baseline (No 

Action) 

3-day storm 

from the east 

No significant 

seafloor changes. 

No significant 

seafloor changes. 

No significant 

seafloor changes. 

3-day storm 

from the 

northeast 

Sand transport from 

NE to SW, resulting 

in deposition along 

the northern polygon 

boundary. Minor 

deposition on leading 

margin of the shoal. 

Dredged polygon 

expected to fill from 

N to S. 

Sand transport from 

NE to SW, resulting 

in deposition along N 

and E polygon 

boundaries. Rapid 

deposition on leading 

margin of the shoal. 

Dredged polygon 

expected to fill from 

NE to SW. 

Moderate zone of 

erosion along crest of 

shoal; deposition 

along leading edge of 

the shoal. No 

observed infilling of 

the dredged area. 

Crest Polygon 

3-day storm 

from the east 

No significant 

seafloor changes; 

long infilling time. 

No significant 

seafloor changes; 

long infilling time. 

No significant 

seafloor changes; 

long infilling time. 

3-day storm 

from the 

northeast 

Erosion on the shoal 

crest enhances 

deposition in the 

dredged polygon at 

the leading edge on 

shoal migration. 

Rapid infilling. 

Most sand eroded 

from the shoal crest 

transported south to 

the leading edge of 

the shoal. Minor 

deposition along the 

eastern edge of the 

dredged polygon. 

No dredging for this 

scenario. Leading/Trailing 

Edge 

3-day storm 

from the east 

No significant 

seafloor changes; 

long infilling time. 

No significant 

seafloor changes; 

long infilling time. 

No dredging for this 

scenario. 

3-day storm 

from the 

northeast 

Sand transport from 

NE to SW, resulting 

in deposition along 

the northern polygon 

boundary. Minor 

deposition on leading 

margin of the shoal. 

Undisturbed rows in 

dredged area provide 

sand for deposition 

throughout polygon, 

Sand transport from 

NE to SW, resulting 

in deposition along N 

and E polygon 

boundaries. Rapid 

deposition on leading 

margin of the shoal. 

Undisturbed rows in 

dredged area provide 

sand for deposition 

throughout polygon, 

Moderate zone of 

erosion along crest of 

shoal; deposition 

along leading edge of 

the shoal. No 

observed infilling of 

the dredged area. 

Striped Pattern 

3-day storm 

from the east 

No significant 

seafloor changes; 

long infilling time. 

No significant 

seafloor changes; 

long infilling time. 

No significant 

seafloor changes; 

long infilling time. 
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The Striped Pattern dredging scenario indicated that trenches in excavated areas fill almost 

uniformly for the length of the “dredged” area. While deposition was greater along the northern 

edges of excavated trenches, each trough showed deposition for most of its length. Deposition 

in the center and southern portions of the “dredged” region is a result of sand erosion from 

undisturbed areas and into adjacent low areas. In terms of timely and uniform recovery of a 

shoal from borrow site dredging, the striped pattern of sediment removal offers great promise. 
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6.0 QUESTIONS AND ALTERNATIVES FOR OPTIMIZING 

PHYSICAL-BIOLOGICAL IMPACTS OF SHOAL DREDGING 

(Tim D. Thibaut – Barry A. Vittor & Associates, inc.; Barry A. Vittor – Barry A. Vittor & Associates, Inc.; 

David B. Snyder – CSA International, Inc.; and Kenyon C. Lindeman – Florida Institute of Technology) 

While formulating monitoring protocols for dredging projects targeting sand shoals, Research 

Planning, Inc. et al. (2001) identified several information gaps concerning physical and 

biological effects. Several questions derived from these information gaps are addressed in this 

section using literature reviews and, where applicable, modeling results. The management goal 

is to efficiently mine or dredge sand from shoals in a way that will lessen the severity and 

duration of biological impacts and be conducive to timely and realistic biological recovery. 

Physical impacts caused by dredging sand shoals on the continental shelf broadly include 

changes in hydrodynamics, grain size composition, and seafloor topography. All of these 

physical alterations affect biotic assemblages at a variety of spatial scales within and among 

shoal features. 

6.1 IS THERE A PREFERRED MANNER TO REMOVE SAND FROM A SHOAL/RIDGE 

FEATURE TO MAXIMIZE THEIR USE AND MAINTAIN THE INTEGRITY OF THE 

FEATURE? 

The analysis of dredging scenarios presented in Section 6.3 indicates that removing sand from 

the leading edge or crest of a shoal is the preferred extraction scenario. However, all proposed 

dredging approaches ensure that a topographic irregularity is maintained to promote long-term 

shoal development. Hayes and Nairn (2004) and Research Planning, Inc. et al. (2001) 

identified a potential concern regarding the degree of offshore sand mining on ridges and 

maintenance of ridge morphology. They suggested that there may be a limit beyond which 

removal of significant quantities of sand from ridges may lead to “deflation” or eventual 

disappearance of the ridge. Because all published literature on shelf sand ridges emphasize 

modern depositional processes when describing formation and maintenance of these features 

(based on coring and seismic data), the mechanism by which shoal “deflation” would occur is 

unknown, unless the entire shoal was physically removed. As long as a seafloor irregularity 

remains upon which to reform the ridge, dominant shelf processes will construct these features 

as described by all shelf ridge process models (see Section 1.1). Therefore, losing the original 

structure of a dredged sand shoal should not be a concern for managers unless the entire 

feature is removed. 

6.2 ARE THERE BENTHIC BIOLOGICAL DIFFERENCES THAT RUN 

LONGITUDINALLY ALONG THE RIDGE AND SHOAL FEATURES SUCH THAT 

DREDGING OPERATIONS SHOULD BE TAILORED TO AVOID CERTAIN AREAS? 

Benthic stations in the study area show some consistency in community composition along the 

longitudinal axes of shoals, but there are differences in community patterns comparing the 

current-facing and lee sides of shoals. The leading edges of Weaver and Isle of Wight Shoals 

in particular have steep slopes, with coincident changes in resident macrobenthos to the south 

of the shoals. On the lee side of Weaver Shoal there are aggregations of tube-building 

polychaetes, areas of shelly sediments, and sand ripples that provide refuge for motile 

assemblages of epifauna (Diaz et al., 2003). Mining sites that have structural complexity may 

be less favorable in ecological terms than targeting other subareas of a shoal with homogenous 

coarse sand habitat. Removal of habitat structure in relatively heterogeneous soft-sediment 

systems may potentially decrease local biodiversity (Thrush et al., 2001). In addition, the lee 
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sides of area shoals are relatively sheltered from the prevailing hydrographic regime. Mining in 

these areas may result in dredging sites that are depositional due to hydrodynamic flow 

deceleration that occurs on the lee side of elevated bedforms (Abelson and Denny, 1997). 

Such sediment deposition could potentially result in burial of benthic organisms. 

The presence of shoals affects patterns of distribution of benthic fauna. Similar to the study 

area, subtidal systems in other locations have lower faunal abundance and diversity on shoals 

compared to the surrounding seafloor (Boesch, 1979; Viscido et al., 1997; Kaiser et al., 2004). 

Community structure of subtidal sediments is controlled primarily by benthic disturbances and 

physical stresses (Whitlatch, 1977; Probert, 1984; Thrush et al., 1996), and habitats affected by 

harsh physical forces may exhibit less diversity than more stable environments (Sanders, 1968). 

Cross-shelf changes in benthic community patterns are well documented (Day et al., 1971; Flint 

and Holland, 1980; Wigley and Theroux, 1981; Tenore, 1985), including increases in diversity 

with greater depth. The occurrence of more diverse benthic communities in deeper water is 

presumably due to more stable hydrographic conditions compared to shallow turbulent zones 

(Day et al., 1971; Flint and Holland, 1980). A high-disturbance with dynamic low diversity may 

also occur within areas of relatively minor change in absolute depth, due to local bathymetry. 

Since shoals are higher than the adjacent seabed, they are exposed to more turbulence from 

storm-generated waves and currents. Benthic shear flow and its related physical parameters 

(sediment regime, sediment stability, pore water oxygenation) have strong controlling effects on 

the composition of benthic invertebrate assemblages (Hall, 1994; Snelgrove and Butman, 

1994). The ecologies of shoal fauna may reflect the energetic hydrodynamics of these 

locations. Shoal crest constituents include suspension-feeding fauna such as tunicates, surf 

clams, and sand dollars, as well as agile burrowing amphipods and lady crabs. 

Because of greater exposure to wave-generated turbulence, the benthic community may 

generally recover more rapidly in mined sites on shoal crests, compared to lower areas of the 

shoals. In coarse sediment habitats with strong currents, subsurface hydrology provides deeper 

oxygenation and more rapid flushing of interstitial water. Higher locations on shoals may 

therefore have more rapid amelioration of degraded surface and pore-water hydrology that often 

results from dredging. Higher portions of the shoals also experience greater sediment mobility, 

potentially resulting in more rapid sediment reworking and infilling of dredged sites. Moreover, 

episodic accumulations of organic material, which may increase biological oxygen demand and 

result in hypoxia or anoxia, may be less likely to persist in a site that is exposed to greater 

turbulence. Collie et al. (2000) reviewed numerous published studies investigating fishing gear 

effects on benthic habitats and found that faunal recovery appears most rapid in less physically 

stable environments. Absent of any management concerns of mining sediments from shoal 

crests, it may be most advantageous to select those dynamic sites with potential for more rapid 

post-dredging recovery. 

6.3 ARE THERE PROCEDURES TO DREDGE SHOAL AND RIDGE FEATURES THAT 

WILL MINIMIZE ECOLOGICAL IMPACTS AND/OR SPEED RECOVERY? 

To address this question, results of dredging scenarios described in Section 5.0 for infilling 

amounts and rates were examined. The four scenarios were as follows 

 Dredging a hole over a restricted area on the crest of a shoal, equivalent to standard 

approaches to dredging a shoal; 

 Dredging the leading edge of a shoal; 

 Dredging the trailing edge of a shoal; and 
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 Dredging in a striped pattern to facilitate recruitment of benthic invertebrates into dredged 

areas. 

In summary, the most desirable location or subarea (crest, leading edge, or trailing edge) of a 

shoal for dredging is the leading edge. This is due primarily to net long-term deposition and 

faster infilling rates of dredged areas. The crest would be a second choice followed by the 

trailing edge. In terms of the dredging removal method, the striped pattern showed the most 

promise with respect to infilling rate. Shallow striped areas in the modeling scenarios rapidly 

recovered to pre-dredging levels. There are other system drivers that may influence differing 

measures of biological recovery including variability in supply, transport, and settlement of 

larvae for some species on a spatial scale that greatly exceeds the shoal area itself. 

Physical results of each modeling scenario are described in the following subsections along with 

a discussion relating potential biological response to those results. A primary emphasis in 

analyzing biological response was potential for recovery to pre-dredging conditions. A brief 

discussion of direct and indirect recovery and the nature of recovery of dredge-related impacts 

is provided herein. 

Dredging shoal areas directly affects existing infauna, epifauna, and fish assemblages. For 

example, entire infaunal assemblages are directly removed with the mined sand during 

dredging. Epifauna including crabs, shrimps, and some demersal fishes may also be removed 

from dredged areas through entrainment. Loss of invertebrates and fishes translate into 

decreased prey items for larger fishes and would be considered an indirect effect. Many of the 

federally managed species discussed in Sections 4.2 and 4.3 are demersal feeders and will be 

indirectly affected. 

In addition to direct loss of organisms and indirect effects through dredging are changes in shoal 

topography and circulation patterns that would impact fishes and invertebrates that utilize shoals 

in different ways. Changes to the topography of a shoal may result in redistribution of 

invertebrates and fishes that oriented to current patterns created by individual shoal features. It 

is likely that some fishes use shoals as guideposts or orientation points during spawning or 

cross-shelf migrations. 

An important characteristic of marine communities is their resilience, or the capability of 

returning to an initial state following a disturbance. Although the recovered states will vary in 

terms of species composition and possibly trophic function, differences reflect variability 

inherent in the assembly of all natural communities. Marine organisms will successfully 

recolonize unoccupied space if that space provides necessary ecological requirements for 

individual species. Because most species possess a two-phase life cycle consisting of a 

sedentary benthic phase and a dispersive planktonic phase capable of moving great distances 

from the natal area, there are potential colonists always available in the local and regional 

species pool. Nonplanktonic immigrants (motile invertebrates, adult, and juvenile fishes) from 

nearby habitats may also recolonize disturbed areas. 

Recovery includes reassembly by various species leading to reestablishment of infaunal, 

epifaunal, and fish assemblages. A major premise of the recovery process is that if the physical 

habitat structure is restored to a facsimile of the pre-dredging condition, biota will follow suit. 

Due to natural variability, this may be only partially true and some areas may be more 

productive than other structurally similar areas (Stoner, 2003). Nevertheless, for this study it 

was assumed that restoring physical conditions would lead to an acceptable ecological recovery 

and that infilling of dredge areas was a key factor contributing to that process. 
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Dredging removes sediments and benthic invertebrates, and there must be some degree of 

physical recovery before benthic recolonization occurs (Newell et al., 1998). The nature of 

biological recovery after dredging, will depend in part on site topography and its orientation to 

the prevailing hydrographic regime. Bottom shear generally slows hydrodynamic flow as 

currents move across seafloor depressions (Nowell and Jumars, 1984; Grove et al., 1991; 

Abelson and Denny, 1997), such as those created by dredging. Flow regime in the benthic 

boundary layer is an important factor regulating the composition of soft sediment benthic 

assemblages (Nowell and Jumars, 1984; Hall, 1994; Snelgrove and Butman, 1994; Newell et 

al., 1998; Crimaldi et al., 2002; Hentschel and Herrick, 2005). Bathymetric depressions formed 

by dredging may create a potentially depositional habitat with relatively limited sediment 

mobility. Depressions often support faunal assemblages that differ from nearby areas without 

depressions (Boesch, 1972; Camp et al., 1977; Wigley and Theroux, 1981; Auster, 1987; Lyons, 

1989; Auster et al., 1991; Able and Kaiser, 1994; Byrnes et al., 2000; Diaz et al., 2003). 

Benthic community patterns vary with location on and near the shoals, in part due to variable 

exposure to the prevailing hydrodynamic regime. Since the target sites vary in shoal location 

and pattern of excavation, there are potential implications for the ecological consequences of 

dredging among the alternative mining scenarios. The nature of biological recovery, including 

the speed of colonization and the composition of the recovered community, will depend in large 

measure on physical characteristics of a site after dredging. Biological recovery can be inferred 

from physical measurements such as post-dredging bathymetry, near-bottom microcirculation, 

and the rate and nature of infilling of excavated sites, as well as an array of biological measures 

that interface with these physical processes including larval recruitment, compositional 

similarity, and trophic interactions. 

Although much attention has been given to turbidity effects from dredging, most discussions 

have focused on estuaries, embayments, and enclosed waters (e.g., Sherk and Cronin, 1970; 

Sherk, 1971; Sherk et al., 1975; Moore, 1977; Peddicord and McFarland, 1978; Stern and 

Stickle, 1978; Herbich and Brahme, 1991; LaSalle et al., 1991; Kerr, 1995; Newcombe and 

Jensen, 1996; Wilber and Clarke, 2001). Turbidity effects appear less important in unprotected 

offshore areas for several reasons. Offshore sands tend to be coarser, with less clay and silt 

than inshore areas. The open ocean environment also provides more dynamic physical 

oceanographic conditions, which minimize settling effects. In addition, offshore organisms are 

adapted to sediment transport processes, which create scouring, natural turbidity, and 

sedimentation under storm and normal conditions. As such, impacts should be evaluated in 

light of natural variability as well as high-level disturbances associated with such events as 

storms, trawling, and floods (Sosnowski, 1984; Herbich, 1992). 

6.3.1 Dredging a Hole Over a Restricted Area on the Crest of a Shoal, Equivalent to 

Standard Approaches to Dredging a Shoal 

To model the potential for benthic habitat recovery, the crest of Weaver Shoal had a simulated 

excavation depth of 3 m below ambient grade, whereas a larger area of the crest on Isle of 

Wight Shoal was excavated to a depth of only 2 m. Despite a deeper excavation, simulated 

infilling during a major storm event was substantially greater at Isle of Wight Shoal (40,000 m3

) 

compared to Weaver Shoal (8,000 m3

). Under the modeled scenarios, physical and thus 

benthic recovery may occur more rapidly with a crest excavation on Isle of Wight Shoal 

compared to Weaver Shoal. Shoal A shows little change in morphology due to a major storm 

compared with the Baseline scenario. Compared to Weaver Shoal and Isle of Wight Shoal, the 

benthic community in an excavated site on the crest of Shoal A may take longer after dredging 

to attain similarity with adjacent nondredged areas due to potential for slower infilling. 
MMS Study 2010-010

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Until some degree of infilling and new recruitment events occur, excavated sites will undergo 

substantial short-term declines in abundances of those species partially removed by the 

dredging. During these recovery periods, the excavation site may support benthic assemblages 

that differ from adjacent nondredged areas of the shoals. The time required to attain a condition 

that is similar to adjacent nondredged areas of the shoals may depend particularly on episodic 

turbulence due to storm-generated wave action. 

Modeling in the present study indicates that during a major storm from the northeast, both 

Weaver Shoal and Isle of Wight Shoal will experience sand transport southward into their 

respective dredged sites on the crest. There is greater infilling at the northeast extent of the 

dredged sites, and little deposition in the central portions of the excavated areas. It is expected 

that as the dredged areas continue to fill during successive storms, the southern extent of the 

dredged areas of Weaver and Isle of Wight Shoals would be the last regions to fill. 

Infilling of disturbed sites may be a significant component for attaining a biological condition 

similar to adjacent nondisturbed areas (Veer et al., 1985; Newell et al., 1998; Dernie et al., 

2003; Boyd et al., 2005), provided that the imported sediments are similar to the sediments of 

the surrounding area (Veer et al., 1985; Hall, 1994; Van Dalfsen et al., 2000; Boyd et al., 2005). 

Sedimentary habitat (particle size, degree of sorting, organic content) often has a strong 

correlation with benthic assemblage composition. If the sedimentary habitat of the infilled site 

differs from the pre-dredging condition and that of the surrounding area, the reestablished 

community in a dredged site may differ from adjacent nondredged areas. The sediment source 

for infilling dredged sites of the study area is shoal material. Because the sediment regime of 

the recovered dredged sites would be similar to that of the unaffected portions of the shoal, 

long-term (i.e., years) community composition effects due to sedimentary habitat differences 

with nondredged areas of the shoals are unlikely. For fishes, the creation of substantial vertical 

relief may be utilized by various species to take advantage of feeding or shelter opportunities at 

small fronts created by angular relief or other indirect habitat features. 

A persistent state of altered benthic community composition in mined sites would most likely be 

due to effects of local microcirculation changes caused by slowed hydrodynamic flow across the 

excavated areas, coupled with biological processes. Though the study area has limited amounts 

of very fine sediments, there is potential for fine materials to accumulate in dredged sites and 

degrade habitat quality (Veer et al., 1985; Barry A. Vittor & Associates, Inc., 1999). 

Reduced flow velocity across the dredged site may affect larval invertebrate behavior and 

settlement (Butman, 1987; Abelson and Denny, 1997) as well as fishes that undergo early larval 

settlement (Lindeman et al., 2001; Kingsford et al., 2002); and attract other motile macrofauna 

(Camp et al., 1977; Lyons, 1989; Diaz et al., 2003). Potential ecological benefits of swales and 

depressions include better individual control of motility in less turbulent locations (Auster, 1987; 

Weston, 1988; Auster et al., 2003), increased foraging efficiency due to more efficient 

chemosensory processes (Moore et al., 1994; Weissburg et al., 2002; Hazlett et al., 2006), and 

greater refuge value due to increased spatial complexity (Jacobi and Langevin, 1996). 

Regardless of the actual species composition of the recovered benthic community, the 

assemblage composition of dredged sites would change through time, as occurs naturally in 

sedimentary habitats of the open shelf. Demersal fishes would be expected to forage in 

recovering areas opportunistically in relation to species-specific characteristics of body size and 

diet. These changes would reflect reassembly of invertebrate communities and alterations of 

food web architecture over time. 
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The relationship between abundance of fishes and invertebrates on crests in comparison to 

flanks is complicated by an absence of direct information and the dynamics of the physics and 

biological responses of these areas. The important structure-building worm, Diopatra, does not 

appear to show high concentrations on crests (VIMS, 2000). The tube-dwelling polychaete 

Asabellides commonly forms mats in the intershoal trough areas but does not occur on high 

areas of shoals. Some motile burrowers, such as lady crabs and certain amphipods, may have 

higher concentrations on crests (Viscido et al., 1997; VIMS, 2000). Developing more 

information on the comparative roles of flank and crest habitats and their difference on leading 

edge versus trailing edge slopes should be a priority in assessing environmental impacts on 

differing shoal habitats. 

6.3.2 Dredging the Leading Edge of a Shoal 

Under a significant storm from the northeast, the greatest deposition on the leading edge of 

Weaver Shoal was observed along the southwest face of the shoal, with a thin band of accretion 

also appearing along the southeast margin of the “dredged” area. This pattern is similar to that 

observed in other excavation scenarios, with the exception being that most deposition occurs 

closer to the crest of the shoal as a result of the dredged region extending toward the crest. 

The leading edge of Weaver Shoal transitions to a steep slope, leading to a deep area on the 

southeast side of the shoal. There is an abrupt change in benthic community composition 

across a relatively short horizontal distance from the shoal crest to the backside slope and 

swale area, presumably due to changes in depth and microcirculation patterns. Bathymetric 

features as small as sand ripples affect near-bottom circulation due to wave-induced shear 

stress (Pana et al., 2007), and local microcirculation changes may affect the composition of 

benthic assemblages in sedimentary habitats (Nowell and Jumars, 1984; Barros et al., 2004). 

The presence of an elevated bedform such as Weaver Shoal causes flow to accelerate as water 

moves toward its widest cross-section (Abelson and Denny, 1997). But on the downstream 

(lee) side, flow decelerates creating a current shadow (Grove et al., 1991). 

Comparing the two scenarios for Weaver Shoal, simulated infilling was greater for an excavation 

of the leading edge (26,000 m3

) compared to the shoal crest (8,000 m3). Mining the leading 

edge of Weaver Shoal may involve trade-offs between more rapid infilling and increased 

potential for prolonged community alteration, due to being relatively sheltered from strong 

northeastern currents. 

Current shadows occur when high current velocities dissipate shed eddies, leaving an area of 

low current velocities on the lee side of a bedform. Because of its more sheltered location on 

the southeast side of Weaver Shoal, mining the shoal’s leading edge has greater potential over 

time to accumulate particulate organic material or very fine (mud and silt) sediments, compared 

to excavation on shoal crests or lower areas on the current-facing side of the shoals. An 

increase in the silt, mud, or organic content of surface sediments would likely prevent 

community recovery to a state that is similar to the adjacent nondredged substrata (Veer et al., 

1985; Barry A. Vittor & Associates, Inc., 1999). Even without infilling of very fine material, 

composition of the recovering assemblage in a leading edge dredge site may differ from the 

adjacent area due to changes in hydrodynamic flow characteristics (Snelgrove and Butman, 

1994). 

Community composition in deeper areas on the lee side of the shoal can reflect diminished 

bottom shear flow. Swales in the study area have relatively high organic content and higher 

proportions of sediment fines, and support greater individual abundance, numbers of taxa, and 
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biomass compared to shoal crests (VIMS, 2000). Aggregations of tube-builders inhabit deeper 

areas on the lee side of Weaver Shoal. Given sufficient time, reduced hydrodynamic flow and 

possibly organic enrichment in a leading edge excavation may facilitate colonization by 

deposit-feeding benthos characteristic of swales, including tube-dwelling amphipods (Ampelisca

spp. and Unciola spp.) and the polychaete Asabellides oculata. It is assumed that if such an 

assemblage became established it would eventually be buried by infilling of the dredged site, 

yet this may vary among shoals and time periods. These patches of tube dwelling organisms 

provide structural habitat for small fishes and other organisms (e.g., Diaz et al., 2003). 

Fishes that normally occur in the water column such as striped bass, bay anchovy, Atlantic 

menhaden, Atlantic mackerel, Spanish mackerel, or spiny dogfish may utilize the current 

shadow as refuge from high velocity waves and currents. Excavation of the leading edge could 

lead to basic changes in the nature of the current refuge or even elevated, albeit short term, 

turbidity that would degrade the habitat value. The relative usage patterns of flanks and crests 

by fishes that use current shadows in the water column currently is poorly known, though flanks 

of lee sides would seem to have value for species trying to physically remain within a current 

shadow. 

6.3.3 Dredging the Trailing Edge of a Shoal 

The trailing edges of study area shoals are largely erosional under natural conditions, supplying 

sand to the shoal crests and leading edges. Sediments therefore may not be as readily 

replaced at dredge sites on the trailing edge compared to locations on the crest or leading edge 

of a shoal. Prolonged bathymetric alteration after excavating a seafloor site may result in 

persistent changes in benthic community composition (Veer et al., 1985; Barry A. Vittor & 

Associates, Inc., 1999; Dernie et al., 2003). Mining on the trailing edge of Weaver Shoal, or 

generally in sites that are naturally erosional, may result in longer periods of benthic community 

alteration after cessation of dredging, due to slow infilling. 

For a trailing edge excavation on Isle of Wight Shoal there are small areas of accretion along 

the periphery of the dredged area closest to the crest. Most of the sediment moved from the 

crest is deposited along the southeast face of the shoal. There is little forcing during this event 

to move suspended sediment over the crest to the north and into the “dredged” area. 

Compared to crest and striped pattern excavation scenarios, dredging the trailing edge at Isle of 

Wight Shoal may prolong the time required for infilling the excavated site. Compared to other 

scenarios, therefore, dredging the trailing edge may prolong the duration of benthic assemblage 

alteration due to dredging. 

6.3.4 Dredging in a Striped Pattern to Facilitate Recruitment of Benthic Invertebrates 

into Dredged Areas 

A series of long parallel cuts made in a striped pattern would create a greater amount of 

microhabitat in terms of surface area than other dredging methods. However, near-term 

physical disturbances could substantially reduce the seeming microhabitat surface area. 

Species-specific invertebrate and fish microhabitat use of these different types of edges 

requires further investigation. For the striped pattern model runs, excavated troughs began to 

fill while the undisturbed regions between the troughs were eroding. Sand deposition 

associated with the Striped Pattern scenario is spread evenly across the impacted areas rather 

than concentrated at the northeast edge of the “dredged” polygon, as in other scenarios. 

Deposition in the center and southern portions of the excavated areas results from redistribution 

of sand from undisturbed areas between the troughs into adjacent low areas. 
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Leaving relatively undisturbed areas interspersed throughout a dredged site should provide 

some pools of potential colonists within the boundary of the overall dredge area. The rate of 

benthic recolonization largely depends on the sizes of the pools of available colonists and 

temporal variability in spawning and recruitment, and the importance of different recruitment 

processes varies across spatial scales (Smith and Brumsickle, 1989; Günther, 1992; Whitlatch 

et al., 1998; Zajac et al., 1998; Palma et al., 1999; Norkko et al., 2006). Larval recruitment 

increases in importance with increasing size of a disturbed area (Smith and Brumsickle, 1989; 

Günther, 1992), whereas post-larval, juvenile, and adult migration across the seabed is more 

limited across large spatial scales (Smith and Brumsickle, 1989; Günther, 1992; Whitlatch et al., 

1998). It is thus assumed that differences in the relative dispersal ability of different life stages 

should vary with the spatial scale of physical disturbance (Whitchlach et al., 1998; Norkko et al., 

2006). Such scale-dependent variability has potentially significant implications for biological 

recovery of disturbed areas (Levin, 1984; Smith and Brumsickle, 1989; Günther, 1992; Hall et 

al., 1994; Thrush et al., 1996; Pranovi et al., 1998; Whitlatch et al., 1998; Zajac et al., 1998; 

Dernie et al., 2003; Norkko et al., 2006). This scenario maintains a patch structure that would 

be attractive to, and likely promote the survival of fishes emigrating into and settling on the 

recovering areas. As discussed above for invertebrates, variation in larval supply that is related 

to adult spawning in distant and nearby waters will significantly determine how the recovering 

borrow areas are ultimately colonized (Steves et al., 1999). 

Survivorship of post-settlement juveniles and adults in some cases plays a large if not 

determinant role in regulating patterns of benthic community composition (Ólafsson et al., 

1994), and survival of post-larval migrants is potentially important in the benthic recovery 

process (Van Dolah et al., 1984; Cummings et al., 1995; Whitlatch et al., 1998; Jutte et al., 

2002; Stocks, 2002). A large number and variety of soft-bottom macrofauna undergo 

post-settlement dispersal, including species such as surf clam (Snelgrove et al., 1999). Even 

characteristically nonopportunistic species can assume opportunistic behavior during the initial 

phase of the recolonization processes of disturbed areas (Wu and Shin, 1997; Pranovi et al., 

1998; Beukema et al., 1999). Decapods and other motile epifauna would recruit into mined 

sites as physical conditions recover sufficiently to provide suitable habitat. Decapods in 

particular are highly dispersive beginning during juvenile stages, actively seeking and using 

complex habitats after settlement (Hedvall et al., 1989; Palma et al., 1999; Heck et al., 2001; 

Pardo et al., 2007). Minimizing the seabed distance across which crawling or burrowing fauna 

must migrate into dredged sites in general should promote more rapid benthic community 

recovery after dredging. 

In summary, based on geological models of shoal formation there does not appear to be a 

mechanism supporting the idea that the structural integrity of a feature will “deflate” or “unravel” 

when subject to repeated dredging. Benthic biological differences are expected to occur along 

the longitudinal axis of a shoal reflecting the differences that occur across the feature. For 

example, the leading edge, crest, and trailing edge would likely support distinctive assemblages 

and, although variable, these assemblages would be expected to persist longitudinally. This 

suggests that depending on the spatial nature of the individual dredging project, additional 

stratification should be considered when designing monitoring programs. 

In summary, the most desirable location or subarea (crest, leading edge, or trailing edge) of a 

shoal for dredging is the leading edge. This is due primarily to net long-term deposition and 

faster infilling rates of dredged areas. The crest would be a second choice followed by the 

trailing edge. In terms of the dredging removal method, the striped pattern showed the most 

promise with respect to infilling rate. Shallow striped areas in the modeling scenarios rapidly 

recovered to pre-dredging levels. There are other system drivers that may influence differing 
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measures of biological recovery including variability in supply, transport, and settlement of 

larvae for some species on a spatial scale that greatly exceeds the shoal area itself. 
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7.0 RECOMMENDATIONS FOR ENGINEERING OPTIONS 

AND MITIGATION MEASURES 

(Mark R. Byrnes – Applied Coastal Research and Engineering, Inc.; Tim D. Thibaut – Barry A. Vittor & Associates, Inc.; 

Barry A. Vittor – Barry A. Vittor & Associates, Inc.; and Kenyon C. Lindeman – Florida Institute of Technology) 

Numerical modeling and field data may be used to suggest engineering options and mitigation 

measures to avoid deleterious impacts of offshore dredging within the ridge and shoal features 

on the Federal OCS (MMS, 2003). Bathymetry data may provide information on natural 

sediment transport patterns and site-specific aspects of shoal and ridge migration 

characteristics. Physical modeling can provide information to assess potential infilling rates of 

dredged sites, an important component of ecological recovery (Byrnes et al., 2004). Biological 

surveys provide benthic and water-column assemblage composition data and consideration of 

various life history features may be used to formulate reasonable assessments of potential 

recovery dynamics (Diaz et al., 2004). 

Mitigation measures designed to minimize or avoid adverse consequences to natural physical 

processes and benthic biological resources may include targeting shoal and ridge locations that 

may be less susceptible to prolonged physical alteration, compared to the natural condition. 

The nature of biological recovery, including the speed of colonization and benthic assemblage 

composition, particularly for invertebrates and demersal fishes, will depend in large measure on 

the physical characteristics of a site after dredging. The level of coupling between 

bottom-associated assemblages and those of the mid- and upper-water column (e.g., pelagic 

fishes and squid) is not well known on trophic and larval scales and can vary in complicated 

manners (Witman et al., 2004). Focusing on minimizing physical impacts and their duration as 

a way to minimize biological consequences recognizes the potential role of understudied, 

biophysically coupled events that may occur undescribed or unmonitored on the shoals. Many 

prominent fish species are relatively opportunistic in space use (Able, 2005; Able et al., 2006) 

and, in addition, are making massive long distance migrations across a wide shelf every 

6 months. With minimization of physical alterations through the use of engineering options and 

mitigation strategies, persistent changes in community patterns and ecological impairment may 

be avoided during and after sediment mining. 

Targeting shoal and ridge locations that may be less susceptible to prolonged physical alteration 

to presumably speed biological recovery is a valid approach to evaluate dredging 

consequences. There are other system drivers including variability in larval recruitment (larval 

supply, transport, and delivery) that for some species, occur on a spatial scale that exceeds the 

recovery drivers in a particular shoal area. The definitions and measures of recovery will be 

important to any future mining of these shoals. Metrics of recovery should be selected to reflect 

community-wide as well as individual species response to environmental changes caused by 

mining and subsequent recovery. Because of lack of replication and issues with finding 

appropriate reference areas, study designs should consider before-after-control-impact 

(Osenberg et al., 2006) to measure recovery. 

7.1 SPATIAL SCOPE OF POTENTIAL CONSEQUENCES 

The primary environmental consequences of dredging shoals and ridges appear to be 

predominantly limited to the immediate area of mined sites. Large-scale impacts of sand mining 

in OCS waters have not been documented to date. Studies evaluating changes in wave and 

current processes relative to sand mining on offshore shoals have found no significant changes 

in regional sand transport patterns (Hayes and Nairn, 2004; Kelly et al., 2004). 
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132 

In some circumstances, suspended solids introduced into the water column by dredging may be 

transported to adjacent areas by water currents. The probability of significant adverse 

consequences of turbidity will vary with regional differences in the proportion of fine sediments 

and organic material at target sites, and local currents and wave climate. Shoals in the study 

area tend to have coarse sediments with low amounts of clay, silt, and organic material, and 

dredging-induced turbidity is expected to be negligible in the open oceanic waters offshore 

Maryland and Delaware (VIMS, 2000). 

In areas with greater amounts of fine sediments, alternative dredging equipment and methods 

may be used to limit transport and redeposition of suspended solids. In general, cutterhead 

suction dredges produce less turbidity than hopper dredges though they excavate deeper. Well 

designed and properly operated cutterhead dredges can limit sediment suspension to the lower 

portion of the water column. Slow dredging methods also may be used to minimize spillage that 

can increase turbidity near the dredge (Section 2). 

Where far-field sedimentation is minimized, the biological consequences of sand mining are 

likely to be limited to the immediate area of dredged sites (Newell et al., 1998). Mined sites will 

undergo substantial short-term declines in abundances of the benthic populations partially 

removed by the dredging. Long-term effects have not been frequently measured. Biological 

impacts are largely limited to a dredged site in offshore shoal areas of the shelf because the 

dredge removes only a portion of the resident inner shelf populations, primarily infaunal 

invertebrates and potentially some sand-dwelling fishes. The mid-water and bottom dynamics 

of organics within any plumes and the fill path itself are essentially unmeasured. Pathways of 

energy flow among invertebrate and fish components of the food web, for which there is some 

information from the region (Link, 2002), are interrupted for unmeasured periods of time in 

mined sites due to removal of benthic invertebrates and dredging-interrupted prey predator 

relationships among invertebrates and fishes. 

7.2 IMPACTS AT INDIVIDUAL RIDGES AND SHOALS 

There are limits to the amount of sand available from any single ridge or shoal if the feature is to 

be maintained. As long as a seafloor irregularity remains upon which to reform the ridge, 

dominant shelf processes will construct these features as described by shelf ridge process 

models. For a given dredging and beach nourishment interval, it therefore is advisable to 

remove only a portion of a particular ridge or shoal (Sections 3 and 5). 

For a given ridge or shoal, project elements such as target site location, dredging depth, and 

excavation patterns may be designed to avoid persistent physical alteration after cessation of 

dredging. Recommendations for selection of target sites and dredging methods to avoid or 

minimize adverse physical consequences may include: 

 Extract sand from a depocenter, or leading or downdrift margin of a shoal, to avoid 

interrupting natural shoal migration and potentially reduce the time required for site refilling; 

 Avoid dredging in erosional areas that source downdrift depocenters, which also may be 

slow to refill after dredging; 

 Shallow dredging over large areas rather than excavating small but deep pits; and 

 Dredge in a striped pattern to leave sediment sources adjacent to and interspersed 

throughout target areas, leading to a more uniformly distributed infilling process. 

Borrow site geometry should be considered when assessing physical impact producing factors 

for a particular shoal or ridge. While a relatively shallow excavation over a wider area results in 
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more surface area disturbance and greater short-term biological impacts, sediment reworking 

and site infilling in general may proceed more rapidly than would occur with deeper, more 

spatially restricted dredging (Byrnes et al., 1999). In particular, dredging a bathymetrically 

abrupt pit can greatly extend the duration of physical modification and community alteration 

(Barry A. Vittor & Associates, Inc., 1999). Considering shallower excavation options across 

wider areas, infilling rate may be dependent on site-specific factors. In the current study, 

simulated infilling at Isle of Wight Shoal was substantially greater than was modeled for Weaver 

Shoal, and therefore even with a deeper excavation at Isle of Wight Shoal, complete infilling 

may occur more rapidly than in a shallower excavation at Weaver Shoal. Depending on shoal 

or ridge morphology, regional hydrodynamic processes, and biological community composition 

and temporal dynamics for a given target area, it may be necessary to evaluate how to balance 

short- and long-term physical and biological impacts related to depth of excavation (Michel 

et al., 2007). 

Infilling of mined sites reestablishes natural near-bottom hydrodynamic shear flow, and is an 

important process for potentially attaining a biological condition similar to adjacent nondisturbed 

areas. When designing sand mining projects on ridges and shoals of the OCS, information on 

geomorphology and hydrodynamic processes is needed regarding the stability of the feature. 

With bathymetry data that are sufficient to assess natural sediment transport patterns, 

depocenters may be targeted and erosional areas avoided on shoals and ridges. Extracting 

sand from a depocenter implies that recovery or infilling processes would proceed in a way 

consistent with natural long-term depositional processes for a borrow site location. In the 

current study area, bathymetry data indicate that the leading edge of Weaver Shoal has an 

extensive depositional area along its southern margin. Such sites may be ideal locations for 

sand mining because dredging would occur in an area of active natural deposition, which would 

promote infilling after cessation of dredging. 

Bathymetric change data analyzed for the Weaver Shoal study area suggest that the eroding 

portion of a shoal’s trailing edge may be an area to avoid, because dredging in these areas may 

have a direct impact on natural erosion processes that source downdrift depocenters. Dredging 

trailing or otherwise naturally eroding locations may therefore disrupt natural shoal evolution, 

and dredging a trailing edge may prolong the duration of benthic community alteration due to 

relatively slow infilling, compared to leading edge or crest excavations. 

Currently, however, there is no information about biological recovery responses in erosional 

trailing edge and accretional leading edge shoal areas. Therefore, it is unknown whether there 

are substantive differences in critical biological processes such as recruitment success and 

post-settlement mortality in leading and trailing edge habitats. For example, are there skewed 

differences in recruitment success and variability for primary invertebrates and fishes between 

leading and trailing edge areas? These could be fruitful questions for future modeling and field 

investigations. 

Borrow site orientation to the prevailing hydrodynamic regime may be considered when 

assessing physical impact producing factors, and thus potential biological consequences, for a 

particular shoal or ridge. In the Weaver shoal study area, the leading edges of the shoals are 

steep, leading to intershoal troughs to the southeast. At these relatively sheltered locations on 

the lee side of the shoal, current flow slows. Because of a current shadow in these areas, 

mining a leading edge has greater potential over time to accumulate particulate organic material 

or very fine sediments in a borrow site, compared to excavation on shoal crests or lower areas 
MMS Study 2010-010 

134 

on the current-facing side of the shoals. Mining a leading edge may involve trade-offs between 

more rapid infilling and increased potential for prolonged community alteration. 

The usefulness of dredging in a striped pattern to speed physical and biological recovery is 

largely untested. However, modeling indicates that, compared to a continuous excavation 

pattern, dredging in a striped pattern may promote transport and redistribution of sediment after 

dredging. A striped pattern excavation may lead to a uniformly distributed and more rapid 

infilling process compared to continuous excavation. More rapid reestablishment of ambient 

topography and benthic shear flow would facilitate recruitment of fauna characteristic of nearby 

nondredged areas. Much evidence indicates that there is strong local control of recruitment, 

particularly for post-larval life stages that are believed to be important colonizers of disturbed 

areas. Minimizing the seabed distance across which crawling or burrowing fauna must migrate 

into dredged sites in general should promote more rapid benthic community recovery after 

dredging. Compared to a continuous excavation, a striped pattern may also increase the 

surface area of sedimentary habitats and microhabitats used by a wide array of invertebrates 

and fishes during early and adult life stages. 

Further consideration of striped dredging profile is recommended. Determining details of flank 

and crest coverage in terms of surface area and pattern will require future site-specific physical 

and biological analyses. 

Because of greater exposure to wave-generated turbulence, the benthic community may 

recover more rapidly in mined sites on shoal crests compared to lower areas of the shoals. 

Higher locations on shoals and ridges experience greater sediment mobility, potentially resulting 

in more rapid sediment reworking and site infilling. Shoal and ridge crests in the Weaver Shoal 

study area also tend to support less diverse and presumably more resilient invertebrate 

assemblages than those found in surrounding areas of the shoals. 

7.3 RECOMMENDATIONS FOR IMPROVING EFH MANAGEMENT 

Shoals and ridges serve as a benthic nursery area, refuge, and feeding sites for a variety of 

ecologically important and commercially and recreationally harvested fish and invertebrate 

resources (Diaz et al., 2004; Able et al., 2006). Issues requiring consideration in the 

development of EFH Assessments prepared for excavation on OCS shoals should, at a 

minimum, include analysis of those EFH species and life history stages already identified for 

shoal and ridge features. Several management agencies have identified sandy shoals as EFH 

for migratory benthic fishes, including flounder and sharks (Section 4.5). To the south of the 

study area, the South Atlantic Fishery Management Council has also identified shoals as EFH 

for migratory pelagic fishes, including king mackerel and Spanish mackerel. 

For most managed species relatively little is known regarding the use of shoals and ridges as 

EFH. However, substantial information is available and impact assessments can be developed. 

The recommended minimum content for an EFH Assessment should include the affected 

habitat and species (by life history stage); an analysis of direct, indirect, and cumulative effects; 

a literature review including relevant population impact processes; and an analysis of 

alternatives to the proposed action. 

In assessing the consequences of sand mining on EFH of shoal and ridge systems of the 

Federal OCS, thorough analysis requires more than just species life history information and 

patterns of habitat use. In order to fully assess how different techniques of dredging could affect 

fishery resources, site-specific investigations of physical environmental processes are 
MMS Study 2010-010

135 

recommended. Information needs for EFH analyses ideally include assessment of the level of 

importance of geomorphological and hydrodynamic flow regimes with respect to fishery 

resources. 

Information on these physical environmental parameters can facilitate analysis of sand mining 

effects on sediment transport and microcirculation patterns, which greatly influence patterns of 

benthic community structure. When designing sand mining projects, information is needed 

regarding significance of local and regional current patterns to benthic trophics and secondary 

production, temporal production cycles, and reproduction and larval dispersal patterns. 

Biological productivity is affected by location across ridge and shoal systems, and a spatial 

examination may determine if different locations vary in EFH function. Many of the benthic 

invertebrates inhabiting potential shoal mining sites are potential prey for fishes; however, 

forage items and biomass are not distributed evenly. Important fishery resources inhabit shoal 

systems and utilize physically dynamic microhabitats and benthic food items, both of which are 

related to the ambient hydrodynamic flow regime and its related parameters of bathymetry and 

sedimentary habitat. Shoal crests tend to support less diverse invertebrate assemblages than 

those found on the surrounding seafloor. The crests also in general lack bioengineered 

structures at the sediment-water interface, which tend to attract more diverse benthic 

assemblages than occur in nonstructured substrata. In formulating analyses of mining impacts 

on EFH, spatial and temporal variability in resource and stressor distributions should be 

evaluated. 

Many harvested species that can use shoals are subject to management via EFH or 

catch-based fishery regulations, are opportunistic in space use (Able et al., 2006) and are 

making long-distance migrations across a wide shelf every 6 months between diverse end 

points (shallow estuaries and deep OCS habitats). These species and species groups include 

striped bass, bluefish, mackerel species, flounder species, croaker species (sciaenids), and 

squid species. Temporal changes in faunal distributions are, therefore, very important in EFH 

analyses due to transient use of shoals and ridges by both demersal and pelagic species and 

life stages. The available information for two flounder species and two water-column species 

(bay anchovy and striped bass) were examined in terms of distribution and abundance across 

the shelf by habitat, cross-shelf physiographic gradient, and seasonal scales. The use of 

sedimentary and other habitats within shoal areas of the inner OCS suggests that both bottom 

and water-column fishes are often spatially opportunistic in terms of habitat use and cross-shelf 

positioning, though temporally dependent on two annual cross-shelf migrations (e.g., Able et al., 

2006; Sackett et al., 2007). This results in temporally variable EFH values for shoals, with the 

fall and winter as the periods of greatest habitat value for most demersal and water-column 

fishes that undergo seasonal cross-shelf migrations. Able et al. (2006) have found that inner 

shelf fish species typically settle in estuaries or the ocean, or estuaries only, not in the ocean 

only. It appears that the majority of the estuary and ocean settlers settle more abundantly in 

ocean than estuarine areas. The role of shoals as potential settlement habitat remains not well 

known for many species. 
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8.0 LITERATURE CITED 

Abele, L.G. and K. Walters. 1979. Marine benthic diversity: A critique and alternative 

explanation. J. Biogeogr. 6:115-126. 

Abelson, A. and M. Denny. 1997. Settlement of marine organisms in flow. Annu. Rev. Ecol. 

Syst. 28:317-339. 

Able, K.W. 2005. A reexamination of fish estuarine dependence: Evidence for connectivity 

between estuarine and ocean habitats. Est. Coast. Shelf Sci. 64:5-17. 

Able, K.W. and M.P. Fahay. 1998. The First Year of Life in Estuarine Fishes of the Mid-Atlantic 

Bight. Rutgers Univ. Press. 342 pp. 

Able, K.W. and T.M. Grothues. 2007. Diversity of estuarine movements of striped bass 

(Morone saxatilis): A synoptic examination of an estuarine system in southern New 

Jersey. Fish. Bull. 105:426-435. 

Able, K.W. and S.M. Hagan. 1995. Fishes in the vicinity of Beach Haven Ridge: Annual and 

seasonal patterns of abundance during the early 1970s. IMCS Technical 

Report 95-24. Institute of Marine and Coastal Sciences, Rutgers University, New 

Jersey. 36 pp. 

Able, K.W. and S.C. Kaiser. 1994. Synthesis of summer flounder habitat parameters. NOAA 

Coastal Ocean Program Decision Analysis Series No. 1. NOAA Coastal Ocean 

Office. Silver Spring, MD. 68 pp. 

Able, K.W., R.E. Matheson, W.W. Morse, M.P. Fahay, and G.P. Shepherd. 1990. Patterns of 

summer flounder (Paralichthys dentatus) early life history in the Mid-Atlantic Bight and 

New Jersey estuaries. Fish. Bull. 88(1):1-12. 

Able, K.W., M.P. Fahay, and G.R. Shepherd. 1995. Early life history of black sea bass, 

Centropristis striata, in the mid-Atlantic Bight and a New Jersey estuary. Fish. Bull. 

93:429-445. 

Able, K.W., M.P. Fahay, D.A. Witting, R.S. McBride, and S.M. Hagan. 2006. Fish settlement in 

the ocean vs. estuary: Comparison of pelagic larval and settled juvenile composition 

and abundance from southern New Jersey, USA. Est. Coast. Shelf Sci. 66:280-290. 

Able, K.W., J.H. Balletto, S.M. Hagan, P.R. Jivoff, and K. Strait. 2007. Linkages between salt 

marshes and other nekton habitats in Delaware Bay, USA. Rev. Fish. Sci. 15:1-61. 

Aguilar, R., A.H. Hines, M.A. Kramer, T.G. Wolcott, and R. Lipcius. 2005. Timing and route of 

movement and migration of post-copulatory female blue crabs, Callinectes sapidus 

Rathbun, from the upper Chesapeake Bay. J. Exp. Mar. Biol. Ecol. 319:117-128. 

Allen, J.D. and B. Pernet. 2007. Intermediate modes of larval development: Bridging the gap 

between planktotrophy and lecithotrophy. Evol. Dev. 9:643-653. 

Andrew, N.L. and B.D. Mapstone. 1987. Sampling and the description of spatial pattern in 

marine ecology. Oceanogr. Mar. Biol. Annu. Rev. 25:39-90. 
MMS Study 2010-010 

138 

Arendt, M.D., J.E. Olney, and J.A. Lucy. 2001. Stomach content analysis of cobia, 

Rachycentron canadum, from lower Chesapeake Bay. Fish. Bull. 99:665-670. 

Ault, J.S., G.A. Diaz, S.G. Smith, J. Luo, and J.E. Serafy. 1999. An efficient sampling survey 

design to estimate pink shrimp population abundance in Biscayne Bay, Florida. N. 

Amer. J. Fish. Manage. 19:696–712. 

Auster, P.J. 1987. The effect of current speed on the small scale spatial distribution of fishes. 

Symposia Series for Undersea Research 2(2):7-16. National Oceanic and 

Atmospheric Administration, Office of Undersea Research, Rockville, MD. 

Auster, P.J., R.J Malatesta, S.C. LaRosa, R.A. Cooper, and L.L. Stewart. 1991. Microhabitat 

utilization by the megafaunal assemblage at a low relief outer continental shelf site - 

Middle Atlantic Bight, USA. J. Northw. Atl. Fish. Sci. 11:59-69. 

Auster, P.J., R.J. Malatesta, and S.C. LaRosa. 1995. Patterns of microhabitat utilization by 

mobile megafauna on the southern New England (USA) continental shelf and slope. 

Mar. Ecol. Prog. Ser. 127:77-85. 

Auster, P.J., J. Lindholm, S. Schaub, G. Funnell, L.S. Kaufman, and P.C. Valentine. 2003. Use 

of sand wave habitats by silver hake. J. Fish Bio. 62:143-152. 

Baird, D. and R.E. Ulanowicz. 1989. The seasonal dynamics of the Chesapeake Bay 

ecosystem. Ecol. Monogr. 59:329-364. 

Barnes, R.D. 1980. Invertebrate Zoology, Fourth Edition. W.B. Saunders College, 

Philadelphia, PA. 

Barros, F., A.J. Underwood, and P. Archambault. 2004. The influence of troughs and crests of 

ripple marks on the structure of subtidal benthic assemblages around rocky reefs. 

Estuar. Coast. Shelf Sci. 60:781-790. 

Barry A. Vittor & Associates, Inc. 1999. Pre- and post-dredging monitoring of 

macroinvertebrate assemblages at a borrow area located offshore of Coney Island, 

New York: 1992-1998 Data Synthesis. U.S. Army Corps of Engineers, New York 

District, 10 pp. + app. 

Battjes, J.A. and J.P. Janssen. 1978. Energy loss and set-up due to breaking of random 

waves, pp. 569-587. Proceedings of the 23rd International Conference on Coastal 

Engineering, American Society Civil Engineers, NY. . 

Beardsley, R.C. and C.D. Winant. 1979. On the mean circulation in the Mid-Atlantic Bight. 

J. Phys. Oceanogr. 9:612-619. 

Bertram, D.F. and W.C. Leggett. 1994. Predation risk during the early life history periods of 

fishes: Separating the effects of size and age. Mar. Ecol. Prog. Ser. 109:105-114. 

Beukema, J.J., E.C. Flach, R. Dekker, and M. Starink. 1999. A long-term study of the recovery 

of the macrozoobenthos on large defaunated plots on a tidal flat in the Wadden Sea. 

J. Sea Res. 42:235-254. 

Bhaud, M. 1998. The spreading potential of polychaete larvae does not predict adult 

distributions; consequences for conditions of recruitment. Hydrobiol. 375-376:35-47. 
MMS Study 2010-010 

139 

Biggs, R.B. 1968. Environmental effects of overboard spoil disposal, pp. 477-478. J. Sanit. 

Eng. Div. 94, Number SA3, Proceeding Paper 5979. 

Boesch, D.F. 1972. Species diversity of marine macrobenthos in the Virginia area. 

Chesapeake Sci. 13:206-211. 

Boesch, D.F. 1979. Benthic ecological studies: Macrobenthos. Chapter 6. In: Middle Atlantic 

Outer Continental Shelf Environmental Studies. Final Report to Bureau of Land 

Management. Virginia Institute of Marine Science, Gloucester Point, VA. 

Borthagaray, A. and A. Carranza. 2007. Mussels as ecosystem engineers: Their contribution to 

species richness in a rocky littoral community. Acta Oecologia 31:243-250. 

Bowman, R.E., C.E. Stillwell, W.L. Michaels, and M.D. Grosslein. 2000. Food of northwest 

Atlantic fishes and two common species of squid. U.S. Department of Commerce, 

NOAA Tech Memo NMFS NE 155. 137 pp. 

Boyd, S.E., D.S. Limpenny, H.L. Rees, and K.M. Cooper. 2005. The effects of marine sand 

and gravel extraction on the macrobenthos at a commercial dredging site (results 

6 years post-dredging). ICES J. Mar. Sci. 62:145-162. 

Bray, J.R. and J.T. Curtis. 1957. An ordination of the upland forest communities of southern 

Wisconsin. Ecol. Monogr. 27:325-349. 

Brookins, K.G. and C.E. Epifanio. 1985. Abundance of brachyuran larvae in a small coastal 

inlet over six consecutive tidal cycles. Estuaries 8:80-87. 

Brooks, R.A., C.N. Purdy, S.S. Bell, and K.J. Sulak. 2006. The benthic community of the 

eastern U.S. continental shelf: A literature synopsis of benthic faunal resources. 

Cont. Shelf Res. 26:804-818. 

Bumpus, D.F. 1973. A description of the circulation on the continental shelf of the east coast of 

the U.S. Prog. Oceanogr. 6:111-157. 

Burlas, M., G.L. Ray, and D. Clarke. 2001. The New York District’s Biological Monitoring 

Program for the Atlantic Cost of New Jersey, Asbury Park to Manasquan Section 

Beach Erosion Control Project, Final Report. U.S. Army Corps of Engineers, New 

York District, Engineer Research and Development Center and Waterways 

Experiment Station. 

Butman, C.A. 1987. Larval settlement of soft-sediment invertebrates: the spatial scales of 

pattern explained by active habitat selection and the emerging role of hydrodynamic 

processes. Oceanogr. Mar. Biol. Annu. Rev. 25:113-165. 

Butman, C.A., J.P. Grassle, and C.M. Webb. 1988. Substrate choices made by marine larvae 

settling in still water and in a flume flow. Nature 333:771-773. 

Buttolph, A.M., C.W. Reed, N.C. Kraus, N. Ono, M. Larson, B. Camenen, H. Hanson, 

T. Wamsley, and A.K. Zundel. 2006. Two-dimensional depth-averaged circulation 

model CMS-M2D: Version 3.0, Report 2: Sediment transport and morphology change. 

Coastal and Hydraulics Laboratory Engineering Technical Note ERDC/CHL 

CHETN-IV-50. U.S. Army Engineer Research and Development Center, Vicksburg, 

MS. Report ERDC/CHL-TR-06-7. 

<http://cirp.wes.army.mil/cirp/cetns/chetn-iv50.pdf> 
MMS Study 2010-010 

140 

Byrnes, M.R. and C.G. Groat. 1992. Characterization of the development potential of Ship 

Shoal sand for beach replenishment of the Isles Dernieres: An introduction, 

pp. 75-78. 12th Annual Information Transfer Meeting, U.S. Minerals Management 

Service, New Orleans, LA. 

Byrnes, M.R., R.M. Hammer, B.A. Vittor, J.S. Ramsey, D.B. Snyder, K.F. Bosma, J.D. Wood, 

T.D. Thibaut, N.W. Phillips. 1999. Environmental survey of identified sand resource 

areas offshore Alabama: Volume I: Main Text, Volume II: Appendices. U.S. 

Department of Interior, Minerals Management Service, International Activities and 

Marine Minerals Division (INTERMAR), Herndon, VA. OCS Report MMS 99-0052, 

326 pp. + 132 pp. appendices. 

Byrnes, M.R., R.M. Hammer, B.A. Vittor, J.S. Ramsey, D.B. Snyder, K.F. Bosma, J.D. Wood, 

T.D. Thibaut, and N.W. Phillips. 2000. Environmental survey of potential sand 

resource sites offshore New Jersey. U.S. Department of the Interior, Minerals 

Management Service, International Activities and Marine Minerals Division 

(INTERMAR), Herndon, VA. OCS Report MMS 2000-052. 380 pp. + apps. 

Byrnes, M.R., R.M. Hammer, B.A. Vittor, S.W. Kelley, D.B. Snyder, J.M. Cote, J.S. Ramsey, 

T.D. Thibaut, N.W. Phillips, and J.D. Wood. 2003. Collection of environmental data 

within sand resource areas offshore North Carolina and the environmental 

implications of sand removal for coastal and beach restoration. U.S. Department of 

the Interior, Minerals Management Service, Leasing Division, Sand and Gravel Unit, 

Herndon, VA. OCS Report MMS 2000-056. 256 pp. + apps. 

Byrnes, M.R., R.M. Hammer, and T.D. Thibaut. 2004. Physical and biological effects of sand 

mining offshore Alabama. J. Coast. Res. 20(1):6-24. 

Camp, D.K., N.H. Whiting, and R.E. Martin. 1977. Nearshore Marine Ecology at Hutchinson 

Island, Florida: 1971-1974, V. Arthropods. Flor. Mar. Res. Pub. 25. 

Campbell, B.C. and K.W. Able. 1998. Life history characteristics of the northern pipefish, 

Syngnathus fuscus, in southern New Jersey. Estuaries 21(3):470-475. 

Carr, S.D., R.A. Tankersley, J.L. Hench, R.B. Forward, Jr. and R.A. Luettich, Jr. 2004. 

Movement patterns and trajectories of ovigerous blue crabs Callinectes sapidus

during the spawning migration. Estuar. Coast. Shelf Sci. 60:567-579. 

Centre for Cold Ocean Resources Engineering. 1995. Proposed marine mining technologies 

and mitigation techniques: A detailed analysis with respect to the mining of specific 

offshore mineral commodities. U.S. Department of the Interior, Minerals Management 

Service, Office of International Activities and Marine Minerals, OCS Report MMS 

95-0003, C-CORE Publication 96-C15. 280 pp. + apps. 

Chapman, D.C. and R.C. Beardsley. 1989. On the origin of shelf water in the Middle Atlantic 

Bight. J. Phys. Oceanogr. 19:384-391. 

Chia, F.S., J. Buckland-Nicks, and C.M. Young. 1984. Locomotion of marine invertebrate 

larvae: A review. Can. J. Zoo. 62:1,205-1,222. 

Clancy, M. and C.E. Epifanio. 1988. Distribution of crab larvae in relation to tidal fronts in 

Delaware Bay, USA. Mar. Ecol. Prog. Ser. 57:77-82. 
MMS Study 2010-010 

141 

Clarke, K.R. and R.N. Gorely. 2001. Primer v5: User Manual/Tutorial PRIMER-E. Plymouth, 

United Kingdom. 

Coastline Surveys Limited. 1998. Marine aggregate mining benthic and surface plume study. 

U.S. Department of the Interior, Minerals Management Service, Office of International 

Activities and Marine Minerals, Plume Research Group Report 98/555/03. 168 pp. 

Cocito, S. 2006. Bioconstruction and biodiversity: Their mutual influence. Scientia Marina 

68:137-144. 

Collie, J.S., S.J. Hall, M.J. Kaiser, and I.R. Poiner. 2000. A quantitative analysis of fishing 

impacts on shelf-sea benthos. J. Anim. Ecol. 69:785-798. 

Colton, J.B., Jr., W.G. Smith, A.W. Kendall, Jr., P.L. Berrien, and M.P. Fahay. 1979. Principal 

spawning areas and times of marine fishes, Cape Sable to Cape Hatteras. Fish. Bull. 

76:911-915. 

Colvocoresses, J.A. and J.A. Musick. 1984. Species associations and community composition 

of Middle Atlantic Bight continental shelf demersal fishes. Fish Bull. 82:295-313. 

Conkwright, R.D. and C.P. William. 1996. Offshore sand resources in central Maryland shoal 

fields. Maryland Geological Survey File Report No. 96-3, Baltimore, MD. 57 pp. 

Conkwright, R.D., C.P.Williams, and L.B. Christiansen. 2000. Offshore sand resources in 

northern Maryland shoal fields. Maryland Geological Survey File Report No. 00-2, 

Baltimore, MD. 94 pp. 

Cowen, R.K., J.A. Hare, and M.P. Fahay. 1993. Beyond hydrography: Can physical processes 

explain larval fish assemblages within the Middle Atlantic Bight? Bull. Mar. Sci. 

53(2):567-587. 

Crimaldi, J.P., J.K. Thompson, J.H. Rosman, R.J. Lowe, and J.R. Koseff. 2002. 

Hydrodynamics of larval settlement: The influence of turbulent stress events at 

potential recruitment sites. Limnol. Oceanogr. 47:1,137-1,151. 

Cronin, E.L., R.B. Biggs, D.A. Flemer, G.T. Pfitzmeyer, F. Goodwin, Jr., W.L. Dovel, and D.E. 

Richie, Jr. 1970. Gross physical and biological effects of overboard spoil disposal in 

Upper Chesapeake Bay. University of Maryland, Chesapeake Biological Laboratory, 

Natural Resources Institute Special Report Number 3. 66 pp. 

Cummings, V.J., R.D. Pridmore, S.F. Thrush, and J.E. Hewitt. 1995. Post-settlement 

movement by intertidal benthic macroinvertebrates: Do common New Zealand 

species drift in the water column? New Zealand J. Mar. Fresh. Res. 29:59-67. 

Cutter, G.R. Jr., R.J. Diaz, J.A. Musick, J. Olney, Sr., D.M. Bilkovic, J.P.-Y. Maa, S.-C. Kim, C.S. 

Hardaway, Jr., D.A. Milligan, R. Brindley, and C.H. Hobbs, III. 2000. Environmental 

survey of potential sand resource sites offshore Delaware and Maryland. Final 

Report. Prepared by the Virginia Institute of Marine Science, College of William and 

Mary. U.S. Department of the Interior, Minerals Management Service, International 

Activities and Marine Minerals Division, Herndon, VA. OCS Study 2000-055. 

Day, J.H., J.G. Field, and M.P. Montgomery. 1971. The use of numerical methods to determine 

the distribution of the benthic fauna across the continental shelf of North Carolina. 

J. Anim. Ecol. 40:93-125. 
MMS Study 2010-010 

142 

DeGoursey, R.E. and P.J. Auster. 1992. A mating aggregation of the spider crab (Libinia 

emarginata). J. Northw. Atl. Fish. Sci. 13:77–82. 

Dernie, K.M., M.J. Kaiser, and R.M. Warwick. 2003. Recovery rates of benthic communities 

following physical disturbance. J. Anim. Ecol. 72:1,043-1,056. 

DeVries, M.C., R.A. Tankersley, R.B. Forward, Jr., W.W. Kirby-Smith, and R.A. Luettich, Jr. 

1994. Abundance of estuarine crab larvae is associated with tidal hydrologic 

variables. Mar. Biol. 118:403-413. 

Diaz, R.J., G.R. Cutter, and K.W. Able. 2003. The importance of physical and biogenic 

structure to juvenile fishes on the shallow intercontinental shelf. Estuar. Coasts 

26:12-20. 

Diaz, R.J., G.R. Cutter, Jr., and C.H. Hobbs, III. 2004. Potential impacts of sand mining 

offshore of Maryland and Delaware: Part 2–Biological considerations. J. Coast. Res. 

20(1):61-69. 

Dietl, G.P. and R.R. Alexander. 1997. Predator-prey interactions between the naticids Euspira 

heros (Say) and Neverita duplicata (Say) and the Atlantic surfclam Spisula 

solidissima (Dillwyn) from Long Island to Delaware. J. Shellfish Res. 16 413-422. 

Dittel, A.I. and C.E. Epifanio. 1982. Seasonal abundance and vertical distribution of crab larvae 

in Delaware Bay. Estuaries 5:197-202. 

Dobrzynski, T. and K. Johnson. 2001. Regional Council approaches to the identification and 

protection of habitat areas of particular concern. National Oceanic and Atmospheric 

Administration, National Marine Fisheries Service, Office of Habitat Conservation, 

Silver Spring, MD. 

Drake, P., A. Arias, and M. Rodríguez. 1998. Seasonal and tidal abundance patterns of 

decapod crustacean larvae in a shallow inlet (SW Spain). J. Plankton Res. 

20:585-601. 

Drucker, B.S., W. Waskes, and M.R. Byrnes. 2004. The U.S. Minerals Management Service 

Outer Continental Shelf Sand and Gravel Program: Environmental studies to assess 

the potential effects of offshore dredging operations in Federal waters. J. Coast. Res. 

20(1):1-5. 

Duane, D.B., M.E. Field, E.P. Meisburger, D.J.P. Swift, and S.J. Williams. 1972. Linear shoals 

on the Atlantic inner continental shelf, Florida to Long Island, pp. 447-498. In: D.J.P. 

Swift, D.B. Duane, and O.H. Pilkey (eds.), Shelf Sediment Transport: Process and 

Pattern. Dowden, Hutchinson, and Ross, Stroudsburg, PA. 

Duchêne, J.C. 2004. Early recognition of sediment during settlement of Eupolymnia nebulosa

(Polychaeta: Terebellidae) larvae. Mar. Biol. 145:79-85. 

Dunne, J.A., R.J. Williams, N.D. Martinez. 2004. Network structure and robustness of marine 

food webs. Mar. Ecol. Prog. Ser. 273:291–302. 

Duval, E.J. and K.W. Able. 1998. Aspects of the life history of the seaboard goby, Gobiosoma 

ginsburgi, in estuarine and inner continental shelf waters. Bull. New Jersey Acad. 

Sci. 43(1):5-10. 
MMS Study 2010-010 

143 

Eckman, J.E. 1996. Closing the larval loop: Linking larval ecology to the population dynamics 

of marine benthic invertebrates. J. Exper. Mar. Biol. Ecol. 200:207-237. 

Eckman, J.E., W.B. Savidge, and T.F. Gross. 1990. Relationship between duration of cyprid 

attachment and drag forces associated with detachment of Balanus amphitrite

cyprids. Mar. Biol. 107:111-118. 

Eklund, A. and T.E. Targett. 1991. Seasonality of fish catch rates and species composition from 

the hard bottom trap fishery in the Middle Atlantic Bight (US east coast). Fish. Res. 

12(1):1-22.

Engstrom, S.J. and R.L. Marinelli. 2005. Recruitment responses of benthic infauna to 

manipulated sediment geochemical properties in natural flows. J. Mar. Res. 

63:407-436. 

Epifanio, C.E. 1988. Dispersal strategies of two species of swimming crab on the continental 

shelf adjacent to Delaware Bay. Mar. Ecol. Prog. Ser. 49:243-248. 

Epifanio, C.E. and R.W. Garvine. 2001. Larval transport on the Atlantic Continental Shelf of 

North America: A review. Est. Coast. Shelf Sci. 52:51-77. 

Eriksson, B.K., A. Rubach, and H. Hillebrand. 2006. Biotic habitat complexity controls species 

diversity and nutrient effects on net biomass production. Ecology 87:246–254. 

Fay, C.W., R.J. Neves, and G.B. Pardue. 1983. Species profiles: Life histories and 

environmental requirements of coastal fishes and invertebrates (Mid-Atlantic): Surf 

clam. U.S. Fish and Wildlife Service, Division of Biological Services, 

FWS/OBS-82/11.13. 23 pp. 

Fenchel, T. 1969. The ecology of marine microbenthos IV. Structure and function of the 

benthic ecosystem, its chemical and physical factors and the microfauna communities 

with special reference to the ciliated protozoa. Ophelia 6:1-182. 

Field, M.E. 1980. Sand bodies on coastal plain shelves; Holocene record of the U.S. Atlantic 

inner shelf of Maryland. J. Sed. Petrol. 50:505-528. 

Field, M.E. and D.B. Duane. 1976. Post Pleistocene history of the United States inner 

continental shelf: Significance to the origin of barrier islands. Geol. Soc. Am. Bull. 

87:691-702. 

Flint, R.W. and J.S. Holland. 1980. Benthic infaunal variability on a transect in the Gulf of 

Mexico. University of Texas Marine Science Institute Contribution No. 328. 

Academic Press, London. 14 pp. 

Forster, S. and G. Graf. 1995. Impact of irrigation flux into the sediment: intermittent pumping 

by Callianassa subterranean and “piston-pumping” by Lanice conchilega. Mar. Biol. 

123:335-346. 

Forward, R.B., Jr., J. Swanson, and R.A. Tankersely. 1997. Endogenous swimming rhythms of 

blue crab, Callinectes sapidus, Megalopae: Effects of offshore and estuarine cues. 

Mar. Biol. 127:621-628. 

Franz, D.R. 1977. Size and age-specific predation by Lunatia heros (Say, 1822) on the surf 

clam Spisula solidissima (Dillwyn, 1817) off western Long Island, New York. Veliger 

20:144-150. 
MMS Study 2010-010 

144 

Gabriel, W.L. 1992. Persistence of demersal fish assemblages between Cape Hatteras and 

Nova Scotia, Northwest Atlantic. J. Northw. Atl. Fish. Sci. 14:29-46. 

Garrison, L.P. 1999. Vertical migration behavior and larval transport in brachyuran crabs. Mar. 

Ecol. Prog. Ser. 176:103-113. 

Garrison, L.P. and J.S. Link. 2000. Dietary guild structure of the fish community in the 

northeast United States continental shelf ecosystem. Mar. Ecol. Prog. Ser. 

202:231-240. 

Garvine, R.W. 1987. Observations of the coupled circulation between Delaware Bay and Inner 

continental shelf. Eos Trans. Am. Geophys. Union 68:17-33. 

Giangrande, A., S. Geraci, and G. Belmonte. 1994. Life-cycle and life-history diversity in 

marine invertebrates and the implications in community dynamics. Oceanogr. Mar. 

Biol. Annu. Rev. 32:305-333. 

Gibson, G.D. and A.J.F. Gibson. 2004. Heterochrony and the evolution of poecilogony: 

Generating larval diversity. Evolution 58:2,704-2,717. 

Goda, Y. 1985. Random Seas and Design of Maritime Structures. University of Tokyo Press, 

Tokyo, Japan. 

Gosselin, L.A. and P. Qian. 1997. Juvenile mortality in marine benthic invertebrates. Mar. 

Ecol. Prog. Ser. 146:265-282. 

Grabowski, J.H. and S.P. Powers. 2004. Habitat complexity mitigates trophic transfer on oyster 

reefs. Mar. Ecol. Prog. Ser. 277:291-295. 

Graff, G. 1992. Benthic-pelagic coupling: A benthic view. Oceanogr. Mar. Biol. Annu. Rev. 

30:149-190. 

Grantham, B.A., G.L. Eckert, and A.L. Shanks. 2003. Dispersal potential of marine 

invertebrates in diverse habitats. Ecol. Applic. 13 (Supplement):108-116. 

Gross, T.F., F.E. Werner, and J.E. Eckman. 1992. Numerical modeling of larval settlement in 

turbulent bottom boundary layers. J. Mar. Res. 50:611-642. 

Grosslein, M.D. and T.R. Azarovitz. 1982. Fish distribution, pp. 182. In: MESA New York Bight 

Atlas Monograph 15. New York Sea Grant Institute. 

Grove, R.S., M. Nakamura, and C.J. Sonu. 1991. Design and engineering of manufactured 

habitats for fisheries enhancement, pp. 109-152. In: W. Seaman and L. Sprague 

(eds.), Artificial Habitats for Marine and Freshwater Fisheries. Academic Press, New 

York, NY. 285 pp. 

Günther, C. 1992. Dispersal of intertidal invertebrates: A strategy to react to disturbances of 

different scales? Netherlands J. Sea Res. 30:45-56. 

Hadfield, M.G., E.J. Carpizo-Ituarte, K. del Carmen, and B.T. Nedved. 2001. Metamorphic 

competence, a major adaptive convergence in marine invertebrate larvae. Am. Zool. 

41:1,123-1,131. 

Haefner, P.A., Jr. 1976. Distribution, reproduction and moulting of the rock crab, Cancer 

irroratus Say, 1917, in the mid-Atlantic Bight. J. Nat. Hist. 10:377-379. 
MMS Study 2010-010 

145 

Haefner, P.A., Jr. 1979. Comparative review of the biology of north Atlantic caridean shrimps 

(Crangon), with emphasis on C. septemspinosa. Bull. Biol. Soc. Wash. 3:1-40. 

Haefner, P.A., Jr., and W.A. Van Engel. 1975. Aspects of molting, growth and survival of male 

rock crabs, Cancer irroratus, in Chesapeake Bay. Chesapeake Sci. 16:253-265. 

Hales, L.S., Jr. and K.W. Able. 2001. Winter mortality, growth, and behavior of young-of-theyear of four coastal marine fishes in New Jersey (USA) waters. Mar. Biol. 139:45-54. 

Hall, S.J. 1994. Physical disturbance and marine benthic communities: Life in unconsolidated 

sediment. Oceanogr. Mar. Biol. Annu. Rev. 32:179-239. 

Hall, S.J., D.J. Basford, M.R. Robinson, D.G. Raffaelli, and I. Tuck. 1991. Patterns of 

recolonisation and the importance of pit-digging by the edible crab Cancer pagurus in 

a subtidal sand habitat. Mar. Ecol. Prog. Ser. 72:93-102. 

Hall, S.J., D. Raffaelli, and S.F. Thrush. 1994. Patchiness and disturbance in shallow water 

benthic assemblages, pp. 333-375. In: A.G. Hildrew, P.S. Giller, and D. Raffaelli, 

(eds.), Aquatic Ecology: Scale, Pattern, and Processes. Blackwell Scientific, Oxford, 

UK. 

Hammer, R.M., M.R. Byrnes, D.B. Snyder, T.D. Thibaut, J.L. Baker, S.W. Kelley, J.M. Cote, 

L.M. Lagera, S.T. Viada, B.A. Vittor, J.S. Ramsey, and J.D. Wood. 2005. 

Environmental surveys of potential borrow areas on the central East Florida Shelf and 

the environmental implications of sand removal for coastal and beach restoration. 

U.S. Department of the Interior, Minerals Management Service, Leasing Division, 

Marine Minerals Branch, Herndon, VA. OCS Report MMS 2004-037. 328 pp. + 

apps. 

Hanson, R.B., K.R. Tenore, S. Bishop, C. Chamberlain, M.M. Pamatmat, and J. Tietjen. 1979. 

Benthic enrichment in the Georgia Bight related to Gulf Stream intrusions and 

estuarine outwelling. J. Mar. Res. 39:417-441. 

Hare, J.A. and K.W. Able. 2007. Mechanistic links between climate and fisheries along the 

east coast of the United States: explaining population outbursts of Atlantic croaker 

(Micropogonias undulatus). Fish. Oceanogr. 16(1):31-45. 

Hare, J.A. and R.K. Cowen. 1996. Transport mechanisms of larval and pelagic juvenile 

bluefish (Pomatomus saltatrix) from South Atlantic Bight spawning grounds to Middle 

Atlantic Bight nursery habitats. Limnol. Oceanogr. 41:1,264-1,280. 

Hayes, M.O. and R.B. Nairn. 2004. Natural maintenance of sand ridges and linear shoals on 

the U.S. Gulf and Atlantic Continental Shelves and the potential impacts of dredging. 

J. Coast. Res. 20(1):138-148. 

Hazlett, B.A., P. Acquistapace, and F. Gherardi. 2006. Responses of the crayfish Orconectes 

virilis to chemical cues depend upon flow conditions. J. Crust. Biol., 26(1):94-98. 

Heck, K.L., Jr. and T.A. Thoman. 1984. The nursery role of seagrass meadows in the upper 

and lower reaches of the Chesapeake Bay. Estuaries 7:70-92. 

Heck, K.L. and G.S. Wetstone. 1977. Habitat complexity and invertebrate species richness and 

abundance in tropical seagrass meadows. J. Biogeogr. 4:135-142. 
MMS Study 2010-010 

146 

Heck, L., Jr, L.D. Coen, and S.G. Morgan. 2001. Pre- and post-settlement factors as 

determinants of juvenile blue crab Callinectes sapidus abundance: Results from 

north-central Gulf of Mexico. Mar. Ecol. Prog. Ser. 222:163-176. 

Hedvall, O., P. Moksnes, and L. Pihl. 1989. Active habitat selection by megalopae and juvenile 

shore crabs Carcinus maenas: A laboratory study in an annular flume. Hydrobiologia 

375-376:89-100. 

Hentschel, B.T. and B.S. Herrick. 2005. Growth rates of interface-feeding spionid polychaetes 

in simulated tidal currents. J. Mar. Res. 63:983-999. 

Herbich, J.B. 1992. Handbook of Dredging Engineering. McGraw-Hill, Inc., New York, NY. 

740 pp. 

Herbich, J.B. and S.B. Brahme. 1991. Literature review and technical evaluation of sediment 

resuspension during dredging. U.S. Army Engineer Waterways Experiment Station, 

Vicksburg, MS. Contract Report HL-91-1. 

Hines, A.H. 1986a. Larval patterns in the life histories of brachyuran crabs (Crustacea, 

Decapoda, Brachyura). Bull. Mar. Sci. 39:444-466. 

Hines, A.H. 1986b. Larval problems and perspectives in life histories of marine invertebrates. 

Bull. Mar. Sci. 39:506-525. 

Hongguang, M. and J.P. Grassle. 2004. Invertebrate larval availability during summer 

upwelling and downwelling on the inner continental shelf off New Jersey. J. Mar. 

Res. 62:837-865. 

Howe, S., D. Maurer, and W. Leathem. 1988. Secondary production of benthic molluscs from 

the Delaware Bay and coastal area. Est. Coast. Shelf Sci. 26: 81-94. 

Hrabovsky, L. 1990. Hydraulic Cutterhead Pipeline Dredging. In: D.D. Dickerson and 

D.A. Nelson (comps.), Proceedings of the National Workshop on Methods to Minimize 

Dredging Impacts on Sea Turtles, Jacksonville, FL, U.S. Army Engineer Waterways 

Experiment Station, Vicksburg, MS, Miscellaneous Paper EL-90-5. pp. 56-58. 

Hubertz, J.M., R.M. Brooks, W.A. Brandon, and B.A. Tracy. 1993. Hindcast Wave Information 

for the U.S. Atlantic Coast. WIS Report 30, U.S. Army Engineer Waterways 

Experiment Station. 

Hughes, T.P. and J.H. Connell. 1999. Multiple stressors on coral reefs: A long-term 

perspective. Limnol. Oceanogr. 44(3, Part 2):932-940. 

Hulscher, S.J.M.H., H.E. De Swart, and H.J. De Vriend. 1993. The generation of offshore tidal 

sand banks and sand waves. Cont. Shelf. Res. 13:1,183-1,204. 

Huthnance, J.M. 1982. On one mechanism forming linear sand banks. Est. Mar. Coast. Sci.

14:79–99. 

Ingle, R.M. 1952. Studies on the Effect of Dredging Operations upon Fish and Shellfish. 

Florida State Board of Conservation, Technical Series 5. 26 pp. 

Jacobi, C.M. and R. Langevin. 1996. Habitat geometry on benthic substrata: effects on arrival 

and settlement of mobile epifauna. J. Exper. Mar. Biol. Ecol. 206:39-54 
MMS Study 2010-010 

147 

Johnson, R.O. and W.G. Nelson. 1985. Biological effects of dredging in an offshore borrow 

area. Fla. Sci. 48:166-188. 

Jones, C.G., J.H. Lawton, and M. Shachak. 1994. Organisms as ecosystems engineers. 

Oikos 69:373-386. 

Jones, C.G., J.H. Lawton, and M. Shachak. 1997. Positive and negative effects of organisms 

as physical ecosystem engineers. Ecology 78:1,946-1,957. 

Jones, G. and S. Candy. 1981. Effects of dredging on the macrobenthic infauna of Botany Bay. 

Aust. J. Mar. Fresh. Res. 32:379-399. 

Jones, S.E. and C.F. Jago. 1993. In situ assessment of modification of sediment properties by 

burrowing invertebrates. Mar. Biol. 115:133-142. 

Jonsson, P.R., C. André, and M. Lindegarth. 1991. Swimming behaviour of marine bivalve 

larvae in a flume boundary layer flow: Evidence for near-bottom confinement? Mar. 

Ecol. Prog. Ser. 79:67-76. 

Jutte, P.C., R.F. Van Dolah, and P.T. Gayes. 2002. Recovery of benthic communities following 

offshore dredging, Myrtle Beach, South Carolina. Shore and Beach 70:25-30. 

Kaiser, M.J., M. Bergmann, H. Hinz, M. Galanidi, R. Shucksmith, E.I.S. Rees, T. Darbyshire, 

and K. Ramsay. 2004. Demersal fish and epifauna associated with sandbank 

habitats. Estuar. Coast. Shelf Sci. 60:445-456. 

Keddy, P.A. 1991. Working with heterogeneity: An operator’s guide to environmental gradients. 

In: J. Kolasa and S.T.A. Pickett (eds.), Ecological Heterogeneity. Springer-Verlag, 

New York. 

Kelley, S.W., J.S. Ramsey, and M.R. Byrnes. 2004. Evaluating the physical effects of offshore 

sand dredging for beach nourishment. J. Coast. Res. 20(1):89-100. 

Kerr, S.J. 1995. Silt, turbidity and suspended sediments in the aquatic environment: An 

annotated bibliography and literature review. Ontario Ministry of Natural Resources, 

Southern Region Science and Technology Transfer Unit, Tech. Rep. TR-008. 

277 pp. 

Kingsford , M.J., J.M. Leis, A. Shanks, K.C. Lindeman, S.G. Morgan, and J. Pineda. 2002. 

Sensory environments, larval abilities and local self-recruitment. Bull. Mar. Sci. 

70(1):309-340.

Kristensen, E., M.H. Jensen, and T.K. Andersen. 1985. The impact of polychaete (Nereis 

virens Sars) burrows on nitrification and nitrate reduction in estuarine sediments. 

J. Exper. Mar. Biol. Ecology 85:75-91. 

LaSalle, M.W., D.G. Clarke, J. Homziak, J.D. Lunz, and T.J. Fredette, 1991. A Framework for 

Assessing the Need for Seasonal Restrictions on Dredging and Disposal Operations. 

U.S. Army Engineer Waterways Experiment Station, Vicksburg, MS, Tech. Rep. 

D-91-1. 74 pp. 

Lazzari, M.A. and K.W. Able. 1990. Northern pipefish, Syngnathus fuscus, occurrences over 

the Mid-Atlantic Bight continental shelf: Evidence of seasonal migration. Env. Biol. 

Fish. 27:177-185. 
MMS Study 2010-010 

148 

Levin, L.A. 1984. Life history and dispersal patterns in a dense infaunal polychaete 

assemblage: community structure and response to disturbance. Ecology 

65:1,185-1,200. 

Levinton, J. and B. Kelaher. 2004. Opposing organizing forces of deposit-feeding marine 

communities. J. Exper. Mar. Biol. Ecol. 300:65-82. 

Lindegarth, M., C. André, and P.R. Jonsson. 2002. Physical and numerical modelling of the 

role of hydrodynamic processes on adult-larval interactions of a suspension-feeding 

bivalve. J. Mar. Res. 60:499-516. 

Lindeman, K.C., G.A. Diaz, J.E. Serafy, and J.S. Ault. 1998. A spatial framework for assessing 

cross-shelf habitat use among newly settled grunts and snappers. Proc. Gulf Caribb. 

Fish. Inst. 50:385-416. 

Lindeman, K.C., R. Pugliese, G.T. Waugh, and J.S. Ault. 2000. Developmental patterns within 

a multispecies reef fishery: Management applications for essential fish habitats and 

protected areas. Bull. Mar. Sci. 66(3):929-956. 

Lindeman, K.C., T.N. Lee, W.D. Wilson, R. Claro, and J.S. Ault. 2001. Transport of larvae 

originating in southwest Cuba and the Dry Tortugas: Evidence for partial retention in 

grunts and snappers. Proc. Gulf Caribb. Fish. Inst. 52:732-747. 

Link, J. 2002. Does food web theory work for marine ecosystems? Mar. Ecol. Prog. Ser. 

230:1-9. 

Louis Berger Group. 1999. Use of Federal Offshore Sand Resources for Beach and Coastal 

Restoration in New Jersey, Maryland, Delaware, and Virginia. U.S. Department of 

the Interior, Minerals Management, OCS Study MMS 99-0036. 355 pp. 

Luettich, R.A., Jr., J.J. Westerink, and N.W. Scheffner. 1992. ADCIRC: An Advanced 

Three-Dimensional Circulation Model for Shelves, Coasts, and Estuaries, Report 1: 

Theory and Methodology of ADCIRC-2DDI and ADCIRC-3DL. Dredging Research 

Program Technical Report DRP-92-6. U.S. Army Engineers Waterways Experiment 

Station, Vicksburg, MS. 137 pp. 

Lyons, W.G. 1989. Nearshore Marine Ecology at Hutchinson Island, Florida: 1971-1974. XI. 

Molluscs. Fla. Mar. Res. Pub. 47. 133 pp. 

Maa, J.P.-Y., C.H. Hobbs, S.C. Kim, and E. Wei. 2004. Potential impacts of sand mining 

offshore of Maryland and Delaware: Part 1 - Impacts on physical oceanographic 

processes. J. Coast. Res. 20(1):44-60. 

Mahon, R., S.K. Brown, K.C.T. Zwanenburg, D.B. Atkinson, K.B. Buja, L. Claflin, G.D. Howell, 

M.E. Monaco, R.N. O’Boyle, and M. Sinclair. 1998. Assemblages and biogeography 

of demersal fishes of the east coast of North America. Can. J. Fish. Aquat. Sci. 

55:1,704-1,738. 

Marinelli, R.L. and S.A. Woodin. 2002. Experimental evidence for linkages between infaunal 

recruitment, disturbance, and sediment surface chemistry. Limnol. Oceanogr. 

47:221-229. 

Marsh, G.A. and D.B. Turbeville. 1981. The environmental impact of beach nourishment: Two 

studies in southeastern Florida. Shore and Beach 1981:40-44. 
MMS Study 2010-010 

149 

Martino, E. and K.W. Able. 2003. Fish assemblages across the marine to low salinity transition 

zone of a temperate estuary. Est. Coast. Shelf Sci. 56(5-6):967-985. 

Maurer, D., R.T. Keck, J.C. Tinsman, W.A. Leathem, C. Wethe, C. Lord, and T.M. Church. 

1986. Vertical migration and mortality of marine benthos in dredged material: A 

synthesis. Internationale Revue der Gesamten Hydrobiologie 71:49-63. 

Mayer, L.M., D.F. Schick, R.H. Findlay, and D.L. Rice. 1991. Effects of commercial dragging 

on sedimentary organic matter. Mar. Environ. Res. 31:249-261. 

McBride, R.A. and M.R. Byrnes. 1995. Surficial sediments and morphology of the 

Southwestern Alabama/Western Florida panhandle coast and shelf. Gulf Coast 

Assoc. Geol. Soc. Trans. 45:393-404. 

McBride, R.A. and T.F. Moslow. 1991. Origin, evolution, and distribution of shoreface sand 

ridges, Atlantic inner shelf, U.S.A. Mar. Geol. 97:57-85. 

McBride, R.A., L.C. Anderson, A. Tudoran, and H.H. Roberts. 1999. Holocene stratigraphic 

architecture of a sand-rich shelf and the origin of linear shoals: Northeastern Gulf of 

Mexico, pp. 95-126. In: K.M. Bergman and J.W. Snedden (eds.), Isolated Shallow 

Marine Sand Bodies: Sequence Stratigraphic Analysis and Sedimentologic 

Interpretation. Tulsa, Oklahoma: SEPM (Society for Sedimentary Geologists) Special 

Publication No. 64. 

McBride, R.S. and K.W. Able. 1994. Reproductive seasonality, distribution, and abundance of 

Prionotus carolinus and P. evolans (Pisces: Triglidae) in the New York Bight. Est. 

Coast. Shelf Sci. 38:173-188. 

McBride, R.S. and K.W. Able. 1998. Ecology and fate of butterflyfishes, Chaetodon spp., in the 

temperate, Western North Atlantic. Bull. Mar. Sci. 63(2):401-416. 

McBride, R.S., J.B. O'Gorman and K.W. Able. 1998. Interspecific comparisons of searobin 

(Prionotus spp.) movements, size structure, and abundance in the temperate western 

North Atlantic. Fish. Bull. 96(2):303-314. 

McCaully, J.E., R.A. Parr, and D.R. Hancock. 1977. Benthic infauna and maintenance 

dredging: A case study. Water Res. 11:233-242. 

McConaugha, J.R. 1992. Decapod larvae: dispersal, mortality, and ecology. A working 

hypothesis. Am. Zool. 32:512-523. 

Meyer, T.L., R.A. Cooper, and K.J. Pecci. 1981. The performance and environmental effects of 

a hydraulic clam dredge. Mar. Fish. Rev. 43:14-22. 

Michel, J., R. Nairn, C.H. Peterson, S.W. Ross, R. Weisberg, and R. Randall. 2007. Critical 

technical review and evaluation of site-specific studies techniques for the MMS 

Marine Minerals Program. Minerals Management Service, MMS OCS Report 

2007-047. 47 pp. + apps. 

Mid-Atlantic Fishery Management Council. 1998a. Amendment 12 to the Summer Flounder, 

Scup, and Black Sea Bass Fishery Management Plan. Mid-Atlantic Fishery 

Management Council, Dover, DE. 398 pp. + apps. 
MMS Study 2010-010 

150 

Mid-Atlantic Fishery Management Council. 1998b. Amendment 1 to the Bluefish Fishery 

Management Plan. Mid-Atlantic Fishery Management Council, 2 Vols., Dover, DE. 

341 pp. + apps. 

Mileikovsky, S.A. 1973. Speed of active movement of pelagic larvae of marine bottom 

invertebrates and their ability to regulate their vertical position. Mar. Biol. 23:11-17. 

Milstein, C.B. 1981. Abundance and distribution of juvenile Alosa species off southern New 

Jersey. Trans. Am. Fish. Soc. 110:306-309. 

Milstein, C.B. and D.L. Thomas. 1976. Fishes new or uncommon to the New Jersey coast. 

Chesapeake Sci. 17(3):198-204. 

Milstein, C.B. and D.L. Thomas. 1977. Summary of ecological studies for 1972-1975 in the 

bays and other waterways near Little Egg Inlet and in the ocean in the vicinity of the 

proposed site for the Atlantic generating station, New Jersey. Ichthyological 

Associates, Inc. Bulletin No. 18. 

Minerals Management Service (MMS). 2003. Sand and gravel environmental studies within the 

Minerals Management Service: A framework for decisionmaking. U.S. Department of 

the Interior, Minerals Management Service, Offshore Minerals Management Leasing 

Division. Herndon, VA. 72 pp. 

Modlin, R.F. 1962. The life cycle and recruitment of the sand shrimp, Crangon septemspinosa, 

in the Mystic River estuary, Connecticut. Estuar. Coasts 3:1-10. 

Moore, J.C., E.L. Berlow, D.C. Coleman, P.C. de Ruiter, Q. Dong, A. Hastings, N.C. Johnson, 

K.S. McCann, K. Melville, P.J. Morin, K. Nadelhoffer, A.D. Rosemond, D.M. Post, 

J.L. Sabo, K.M. Scow, M.J. Vanni, and D.H. Wall. 2004. Detritus, trophic dynamics 

and biodiversity. Ecol. Lett. 7:584-600. 

Moore, P.A., M.J. Weissburg, J.M. Parrish, R.K. Zimmer-Faust, and Greg A. Gerhardt. 1994. 

Spatial distribution of odors in simulated benthic boundary layer flows. J. Chem. Ecol. 

20(2):211-222. 

Moore, P.G. 1977. Inorganic particulate suspensions in the sea and their effects on marine 

animals. Oceanogr. Mar. Biol. Annu. Rev. 15:225-363. 

Morrisey, D.J., L. Howitt, A.J. Underwood, and J.S. Stark. 1992. Spatial variation in 

soft-sediment benthos. Mar. Ecol. Prog. Ser. 81:197-204. 

Morse, W.W. and K.W. Able. 1995. Distribution and life history of windowpane, Scophthalmus 

aquosus, off the northwestern United States. Fish. Bull. 93(4):675-693. 

Nairn, R., J.A. Johnson, D. Hardin, and J. Michel. 2004. A biological and physical monitoring 

program to evaluate long-term impacts from sand dredging operations in the United 

States Outer Continental Shelf. J. Coast. Res. 20(1):126-137. 

National Oceanic and Atmospheric Administration (NOAA). 2001. Sea level variations of the 

United States, 1854-1999. NOAA Technical Report NOS CO-OPS 36, Silver Spring, 

MD. 65 pp. 

Natunewicz, C.C. and C.E. Epifanio. 2001. Spatial and temporal scales of patches of crab 

larvae in coastal waters. Mar. Ecol. Prog. Ser. 212:217-222. 
MMS Study 2010-010 

151 

Natunewicz, C.C., C.E. Epifanio, R.W. Garvine. 2001. Transport of crab larval patches in the 

coastal ocean. Mar. Ecol. Prog. Ser. 222:143-154. 

Nelson, W.G. 1988. An overview of the effects of beach nourishment on the sand beach fauna, 

pp. 295-310. In: Proceedings of the 1988 National Conference on Beach 

Preservation Technology, Florida Shore and Beach Preservation Association, 

Tallahassee, FL. 

Nelson, W.G. 1993. Beach restoration in the southeastern US: Environmental effects and 

biological monitoring. Ocean Coast. Mgmt. 19(1993):157-182. 

Neuman, M.J. and K.W. Able. 1998. Experimental evidence of sediment preference by early 

life history stages of windowpane, (Scophthalmus aquosus). J. Sea Res. 40:33-41. 

Neuman, M.J. and K.W. Able. 2002. Quantification of ontogenetic transitions during the early 

life of a flatfish, windowpane, Scophthalmus aquosus (Pleuronectiformes 

Scophthalmidae). Copeia 3:597-609. 

Neuman, M.J., D.A. Witting, and K.W. Able. 2001. Relationships between otolith 

microstructure, otolith growth, somatic growth, and ontogenetic transition in two 

cohorts of windowpane. J. Fish Biol. 58:967-984. 

Newcombe, C.P. and J.O.T. Jensen. 1996. Channel suspended sediment and fisheries: A 

synthesis for quantitative assessment of risk and impact. N. Am. J. Fish. Mgmt. 

16(4):693-727. 

Newell, R.C., L.J. Seiderer, and D.R. Hitchcock. 1998. The impact of dredging works in coastal 

waters: A review of the sensitivity to disturbance and subsequent recovery of 

biological resources on the seabed. Oceanogr. Mar. Biol. Annu. Rev. 36:127-178. 

Newell, R.C., D.R. Hitchcock, and L.J. Seiderer. 1999. Organic enrichment associated with 

outwash from marine aggregates dredging: A probable explanation for surface 

sheens and enhanced benthic production in the vicinity of dredging operations. Mar. 

Poll. Bull. 38(9):808-818. 

Nichols, M., R.J. Diaz, and L.C. Shaffner. 1990. Effects of hopper dredging and sediment 

dispersion, Chesapeake Bay. Environ. Geol. Water Sci. 15:31-43. 

Nixon, S.W. and B.A. Buckley. 2002. A strikingly rich zone—nutrient enrichment and 

secondary production in coastal marine ecosystems. Estuaries 25:782-796. 

Norkko, A., R. Rosenberg, S.F. Thrush, and R.B. Whitlatch. 2006. Scale- and 

intensity-dependent disturbance determines the magnitude of opportunistic response. 

J. Exper. Mar. Biol. Ecol. 330:195-207. 

Nowell, A.R.M. and P.A. Jumars. 1984. Flow environments of aquatic benthos. Annu. Rev. 

Ecol. Syst. 15:303-28 

Ólafsson, E.B., C.H. Peterson, and W.G. Ambrose Jr. 1994. Does recruitment limitation 

structure populations and communities of macro-invertebrates in marine soft 

sediments: The relative significance of pre- and post-settlement processes. 

Oceanogr. Mar. Biol. Annu. Rev. 32:65-109. 

Oliver, J.S. and P.N. Slattery. 1985. Destruction and opportunity on the sea floor: Effects of 

gray whale feeding. Ecology 66:1,965-1,975. 
MMS Study 2010-010 

152 

Onuf, C.P. 1994. Seagrasses, dredging, and light in Laguna Madre, Texas, U.S.A. Est. Coast. 

Shelf Sci. 39:75-91. 

Osenberg, C.W., B.M. Bolker, J.S. White, C. St. Mary, and J.S. Shima. 2006. Statistical issues 

and study design in ecological restorations: Lessons learned from marine reserves, 

pp. 280-302. In: D.A. Falk, M.A. Palmer, and J.B. Zedler (eds.), Foundations of 

Restoration Ecology. Island Press. 

Osman, R.W. and R.B. Whitlatch. 1998. Local control of recruitment in an epifaunal community 

and the consequences to colonization processes. Hydrobiologia 375-376:113-123. 

Overton, A.S., C.S. Manooch, III, J.W. Smith, K. Brennan. 2007. Interactions between adult 

migratory striped bass (Morone saxatilis) and their prey during winter off the Virginia 

and North Carolina coast from 1994 through 2007. Fish. Bull. 106:172-182. 

Oviatt, C.A., C.D. Hunt, G.A. Vargo, and K.W. Kopchynski. 1982. Simulation of a storm event 

in a marine microcosm. J. Mar. Res. 39:605-618. 

Palma, A.T., R.S. Steneck, and C.J. Wilson. 1999. Settlement-driven, multiscale demographic 

patterns of large benthic decapods in the Gulf of Maine. J. Exper. Mar. Biol. Ecol. 

241:107-136. 

Pana, S., N. MacDonald, J. Williams, B.A. O’Connor, J. Nicholson, and A.M. Davies. 2007. 

Modelling the hydrodynamics of offshore sandbanks. Cont. Shelf Res. 

27:1,264-1,286. 

Pardo, L.M., A.T. Palma, C. Prieto, P. Sepulveda, I. Valdivia, and F.P. Ojeda. 2007. Processes 

regulating early post-settlement habitat use in a subtidal assemblage of brachyuran 

decapods. J. Exper. Mar. Biol. Ecol. 344:10-22. 

Parker, S.J., A.W. Shultz, and W.W. Schroeder. 1992. Sediment characteristics and seafloor 

topography of a palimset shelf, Mississippi-Alabama Continental Shelf, pp. 243-251. 

In: Quaternary Coasts of the United States: Lacustrine and Marine Systems. SEPM 

Special Publication 48. 

Parker, S.J., D.J. Davies, and W.E. Smith. 1997. Geologic, economic, and environmental 

characterization of selected near-term leasable offshore sand deposits and 

competing onshore sources for beach nourishment. Geologic Survey of Alabama, 

Environmental Geology Division, Tuscaloosa, AL. Circular 190. 173 pp. + app. 

Pawlik, J.R. 1992. Chemical ecology of the settlement of benthic marine invertebrates. 

Oceanogr. Mar. Biol. Annu. Rev. 30:273-335. 

Pearson, T.H. 2001. Functional group ecology in soft-sediment marine benthos: The role of 

bioturbation. Oceanogr. Mar. Biol. Annu. Rev. 39:233-267. 

Peddicord, R.K. and V.A. McFarland. 1978. Effects of suspended dredged material on aquatic 

animals. U.S. Army Engineer Waterways Experiment Station, Vicksburg, MS, Tech. 

Rep. D-78-29. 102 pp. + app. 

Pineda, J. 2000. Linking larval settlement to larval transport: assumptions, potentials, and 

pitfalls. Oceanogr. East. Pacif. 1:84-105. 

Poiner, I.R. and R. Kennedy. 1984. Complex pattern of change in the macrobenthos of a large 

sandbank following dredging. I. Community analysis. Mar. Biol. 78:335-352. 
MMS Study 2010-010 

153 

Posey, M. and T. Alphin. 2002. Resilience and stability in an offshore benthic community: 

Responses to sediment borrow activities and hurricane disturbance. J. Coast. Res. 

18:685-697. 

Pranovi, F., O. Giovanardi, and G. Franceschini. 1998. Recolonization dynamics in areas 

disturbed by bottom fishing gears. Hydrobiologia 375:125-135. 

Pratt, S. 1973. Benthic fauna. In: Coastal and offshore environmental inventory, Cape 

Hatteras to Nantucket Shoals. University of Rhode Island, Marine Publication Series 

2:5-1-5-70. 

Probert, P.K. 1984. Disturbance, sediment stability, and trophic structure of soft-bottom 

communities. J. Mar. Res. 42:893-921. 

Qian, P. 1999. Larval settlement of polychaetes. Hydrobiologia 402:239-253. 

Reise, K. 2002. Sediment mediated species interactions in coastal waters. J. Sea Res. 

48:127-141. 

Research Planning, Inc., W.F. Baird & Associates Ltd., and Applied Marine Sciences, Inc. 

2001. Development and design of biological and physical monitoring protocols to 

evaluate the long-term impacts of offshore dredging operations on the marine 

environment. U.S. Department of the Interior, Minerals Management Service, 

International Activities and Marine Minerals Division, Herndon, VA. OCS Report 

MMS 2001-089. 

Resio, D.T. and B.A. Tracy. 1983. A Numerical Model for Wind-Wave Prediction in Deepwater. 

WIS Report 12, U.S. Army Engineer Waterways Experiment Station, Coastal 

Engineering Research Center, Wave Information Study, Vicksburg, MS. 

Revsbech, N.P, B. Madsen, and B.B. Jorgensen. 1980. Oxygen in the sea bottom measured 

with a microelectrode. Science 207:1,355-1,356. 

Rhoads, D.C., R.C. Aller, and M.B. Goldhaber. 1977. The influence of colonizing benthos on 

physical properties and chemical diagenesis on the estuarine seafloor, pp. 113-138. 

In: B.C. Coull (ed.) Ecology of Marine Benthos. University of South Carolina Press, 

Columbia, SC. 

Rogers, C.S. 1990. Responses of coral reefs and reef organisms to sedimentation. Mar. Ecol. 

Prog. Ser. 62:185-202. 

Ropes, J.W. 1978. Biology and distribution of surf clams (Spisula solidissima) and ocean 

quahogs (Arctica islandica) off the northeast coast of the United States. In: 

Proceedings of northeast clam industries: Management for the future. 27-28 April 

1978, Hyannis, MA. 

Ropes, J.W. 1980. Biological and fisheries data on the Atlantic surf clam, Spisula solidissima

(Dillwyn). U.S. National Marine Fisheries Service, Northeast Fisheries Center. 

Sandy Hook Lab. Technical Series Report No. 24. 88 pp. 

Rotunno, T. and R.K. Cowen. 1997. Temporal and spatial spawning patterns of the Atlantic 

butterfish, Peprilus triacanthus, in the South and Middle Atlantic Bights. Fish. Bull. 

95(4):785-799. 
MMS Study 2010-010 

154 

Sackett, D.K., K.W. Able, and T.M. Grothues. 2007. Dynamics of summer flounder, 

Paralichthys dentatus, seasonal migrations based on ultrasonic telemetry. Est. 

Coast. Shelf. Sci. 74:119-130. 

Sanders, H.L. 1968. Marine benthic diversity: A comparative study. Am. Nat. 102:243-282. 

Sandifer, P.A. 1973. Distribution and abundance of decapod crustacean larvae in the York 

River estuary and adjacent lower Chesapeake Bay, Virginia, 1968-1969. 

Chesapeake Sci. 14:235-257. 

SAS Institute, Inc. 2007. JMP Version 7.02. SAS Campus Drive, Building S, Cary, NC. 

Scheltema, R.S. 1986. On dispersal and planktonic larvae of benthic invertebrates: an eclectic 

overview and summary of problems. Bull. Mar. Sci. 39:290-322. 

Shanks, A.L. 1995. Mechanisms of cross-shelf dispersal of larval invertebrates and fish, 

pp. 323-367. In: L. McEdward (ed.), Ecology of Marine Invertebrate Larvae. CRC 

Press, Boca Raton, FL. 

Sherk, J.A., Jr. 1971. The effects of suspended and deposited sediment on estuarine 

organisms: Literature summary and research needs. University of Maryland, Natural 

Resources Institute, Chesapeake Biological Laboratory Contribution Number 43. 

73 pp. 

Sherk, J.A., Jr. 1972. Current status of the knowledge of the biological effects of suspended 

and deposited sediments in Chesapeake Bay. Chesapeake Sci. 

13(Suppl.):S137-S144. 

Sherk, J.A., Jr. and L.E. Cronin. 1970. The effects of suspended and deposited sediments on 

estuarine organisms, an annotated bibliography of selected references. University of 

Maryland, Chesapeake Biological Laboratory, Natural Resources Institute, Reference 

Number 70-19. 62 pp. 

Sherk, J.A., J.M. O'Connor, and D.A. Newman. 1975. Effects of suspended and deposited 

sediments on estuarine environments, pp. 541-558. In: L.F. Cronin (ed.), Estuarine 

Research Volume 2, Academic Press, New York, NY. 

Sissenwine, M.P. 1984. Why do fish populations vary? pp. 59-94. In: R.M. May (ed.), 

Exploitation of Marine Communities. Springer-Verlag, Berlin. 

Sisson, C.G. 2002. Dichotomous life history patterns for the nudibranch Dendronotus 

frondosus (Ascanius, 1774) in the Gulf of Maine. Veliger 45:290-298. 

Slacum, H.W.,Jr., W.H. Burton, J.H. Vølstad, J. Dew, E. Weber, R. Llansó, and D. Wong. 2006. 

Comparisons between marine communities residing on sand shoals and 

uniform-bottom substrate in the Mid-Atlantic Bight. U.S. Department of the Interior, 

Minerals Management Service, International Activities and Marine Minerals Division, 

Herndon, VA. OCS Report MMS 2005-042. 149 pp. + apps. 

Smith, C.R. and S.J. Brumsickle. 1989. The effects of patch size and substrate isolation on 

colonization modes and rates in an intertidal sediment. Limnol. Oceanogr. 

34(7):1,263-1,277. 
MMS Study 2010-010 

155 

Smith, J.M., D.T. Resio, and A.K. Zundel. 1999. STWAVE: Steady-State Spectral Wave Model. 

Instructional Report CHL-99-1, U.S. Army Engineering Waterways Experiment 

Station, Vicksburg, MS. 

Snedden, J.W. and R.W. Dalrymple. 1999. Modern shelf sand ridges: From historical 

perspective to a unified hydrodynamic and evolutionary mode, pp. 13–28. In: K.M. 

Bergman and J.W. Snedden (eds.), Isolated Shallow Marine Sand Bodies: Sequence 

Stratigraphic Analysis and Sedimentologic Interpretation. Tulsa, Oklahoma: SEPM 

(Society for Sedimentary Geologists) Special Publication No. 64. 

Snedden, J.W., R.D. Kreisa, R.W. Tillman, W.J. Schweller, S.J. Culver, and R.D. Winn. 1994. 

Stratigraphy and genesis of a modern shoreface-attached sand ridge, Peahala Ridge, 

New Jersey. J. Sed. Res. B64(4):560–581. 

Snedden, J.H., R.P. Kreisa, R.K. Tillman, S.J. Culver, and W.J. Schweller. 1999. An expanded 

model for modern shelf sand ridge genesis and evolution on the New Jersey Atlantic 

shelf, pp. 147-164. In: K.M. Bergman and J.W. Snedden (eds.), Isolated Shallow 

Marine Sand Bodies: Sequence Stratigraphic Analysis and Sedimentologic 

Interpretation. SEPM (Society for Sedimentary Geologists), Tulsa, OK. Special 

Publication No. 64. 

Snelgrove, P.V.R. 1994. Hydrodynamic enhancement of invertebrate larval settlement in 

microdepositional environments: Colonization tray experiments in a muddy habitat. 

J. Exper. Mar. Biol. Ecol. 176:149-166. 

Snelgrove, P.V.R. and C.A. Butman. 1994. Animal-sediment relationships revisited: Cause 

versus effect. Oceanogr. Mar. Biol. Annu. Rev. 32:111-177. 

Snelgrove, P.V.R., J.P. Grassle, and C.A. Butman. 1998. Habitat selection by settling larvae of 

the surf clam, Spisula solidissima in flow and still water. J. Exper. Mar. Biol. Ecol. 

231:171-190. 

Snelgrove, P.V.R., J.P. Grassle, J.F. Grassle, R.F. Petrecca, and H. Ma. 1999. In situ habitat 

selection by settling larvae of marine soft-sediment invertebrates. Limnol. Oceanogr. 

44:1,341-1,347. 

Snelgrove, P.V.R., J.F. Grassle, J.P. Grassle, R.F. Petrecca, and K.I. Stocks. 2001. The role of 

colonization in establishing patterns of community composition and diversity in 

shallow-water sedimentary communities. J. Mar. Res. 59:813-831. 

Sosnowski, R.A. 1984. Sediment resuspension due to dredging and storms: An analogous 

pair, pp. 609-618. In: R.L. Montgomery and J.W. Leach (eds.), Conference 

Proceedings, Dredging ’84, Dredging and Dredged Material Disposal. American 

Society of Civil Engineers, 14-16 November 1984, Clearwater Beach, FL. 

Stehlik, L. 1993. Diet of the brachyuran crabs Cancer irroratus, C. borealis, and Ovalipes 

ocellatus in the New York Bight. J. Crust. Biol. 1,394:723-735. 

Stehlik, L.L., R.A. Pikanowski, and D.G. McMillan. 2004. The Hudson-Raritan Estuary as a 

crossroads for distribution of blue (Callinectes sapidus), lady (Ovalipes ocellatus), and 

Atlantic rock (Cancer irroratus) crabs. Fish. Bull. 102:693-710. 
MMS Study 2010-010 

156 

Steimle, F.W. and C. Zetlin. 2000. Reef habitats in the Middle Atlantic Bight: Abundance, 

distribution, associated biological communities, and fishery resource use. Mar. Fish. 

Rev. 62(2):24-42. 

Steiner, W.W., J.J. Luczkovich, and B.L. Olla. 1982. Activity, shelter usage, growth and 

recruitment of juvenile red hake, Urophycis chuss. Mar. Ecol. Prog. Ser. 7:125-135. 

Stephenson, W.W.T., S.D. Cook, and J.S. Newland. 1978. The macrobenthos of the Middle 

Banks of Moreton Bay. Mem. Queensl. Mus. 18:95-118. 

Stern, E.M. and W.B. Stickle. 1978. Effects of Turbidity and Suspended Material in Aquatic 

Environments: Literature Review. U.S. Army Engineer Waterways Experiment 

Station, Vicksburg, MS. Tech. Rep. D-78-21. 117 pp. 

Steves, B.P., R.K. Cowen, and M.H. Malchoff. 1999. Settelment and nursery habitats for 

demersal fishes on the continental shelf of the New York Bight. Fish. Bull. 

98:167-188. 

Stocks, K.I. 2002. Flume experiments on post-settlement movement in polychaetes. J. Mar. 

Res. 60(5):743-762. 

Stoner, A.W. 2003. What constitutes essential nursery habitat for a marine species? A case 

study of habitat form and function for the queen conch. Mar. Ecol. Prog. Ser. 

257:275-289. 

Strathmann, R.R., T.P. Hughes, A.M. Kuris, K.C. Lindeman, S.G. Morgan, J.M. Pandolfi, and 

R.R. Warner. 2002. Evolution of local-recruitment and its consequences for marine 

populations. Bull. Mar. Sci. Supp. (70):377-396. 

Suess, E. 1980. Particulate organic flux in the oceans – surface productivity and oxygen 

utilization. Nature 288:260-263. 

Sullivan, M.C., R.K. Cowen, K.W. Able, and M.P. Fahay. 2000. Spatial scaling of recruitment in 

four continental shelf fishes. Mar. Ecol. Prog. Ser. 207:141-154. 

Sullivan, M.C., R.K. Cowen, K.W. Able, and M.P. Fahay. 2006. Applying the basin model: 

Assessing habitat suitability of young-of-the-year demersal fishes on the New York 

Bight continental shelf. Cont. Shelf. Res. 26:1,551-1,570. 

Summerson, H.C. and C.H. Peterson. 1984. Role of predation in organizing benthic 

communities of a temperate-zone seagrass bed. Mar. Ecol. Prog. Ser. 15:63-77. 

Swift, D.J.P and M.E. Field. 1981. Evolution of a classic sand ridge field: Maryland sector, 

North American inner shelf. Sedimentology 28:461-482. 

Swift, D.J.P., J.W. Kofoed, F.P. Salsbury, and P. Sears. 1972. Holocene evolution of the shelf 

surface, central and southern Atlantic shelf of North America, pp. 499-575. In: D.J.P. 

Swift, D.B. Duane, and O.H. Pilkey (eds.), Shelf Sediment Transport: Process and 

Pattern. Dowden Hutchinson, and Ross, Stroudsburg, PA. 

Tagatz, M.E. 1968. Biology of the blue crab, Callinectes sapidus Rathbun, in the St. Johns 

River, Florida. Fish. Bull. 67:17-33. 

Tamburri, M.N., C.M. Finelli, D.S. Wethey, and R.K. Zimmer-Faust. 1996. Chemical induction 

of larval settlement behavior in flow. Biol. Bull. 191:367-373. 
MMS Study 2010-010 

157 

Taylor, A.S. 1990. The hopper dredge, pp. 59-63. In: D.D. Dickerson and D.A. Nelson 

(comps.), Proceedings of the National Workshop on Methods to Minimize Dredging 

Impacts on Sea Turtles, Jacksonville, FL, U.S. Army Engineer Waterways Experiment 

Station, Vicksburg, MS, Miscellaneous Paper EL-90-5. 

Tenore, K.R. 1985. Seasonal changes in soft bottom macrofauna of the U.S. South Atlantic 

Bight, pp. 130-140. In: L.P. Atkinson, D.W. Menzel, and K.A. Bush (eds.), 

Oceanography of the Southeastern U.S. Continental Shelf. American Geophysical 

Union, Washington, DC. 

Thistle, D. 1981. Natural physical disturbances and communities of marine soft bottoms. Mar. 

Ecol. Prog. Ser. 6:223-228. 

Thompson, J.R. 1973. Ecological effects of offshore dredging and beach nourishment: A 

review. U.S. Army Engineer Waterways Experiment Station Miscellaneous Paper 

1-73. U.S. Army Corps of Engineers, Coastal Engineering Research Center, Fort 

Belvoir, VA. Report 1-73. 

Thompson, R.C., B.J. Wilson, M.L. Tobin, A.S. Hill, and S.J. Hawkins. 1996. Biologically 

generated habitat provision and diversity of rocky shore organisms at a hierarchy of 

spatial scales. J. Exper. Mar. Biol. Ecol. 202:73-84. 

Thorson, G. 1957. Bottom communities (sublittoral or shallow shelf). In: J.W. Hedgpeth (ed.), 

Treatise on Marine Ecology and Palaeoecology, Volume I. Mem. Geol. Soc. Am. 

67:461-534. 

Thorson, G. 1966. Some factors influencing the recruitment and establishment of marine 

benthic communities. Netherlands. J. Sea Res. 3(2):267-293. 

Thrush, S.F., R.B. Whitlatch, R.D. Pridmore, J.E. Hewitt, V.J. Cummings, and M.R. Wilkinson. 

1996. Scale-dependent recolonization: The role of sediment stability in a dynamic 

sandflat habitat. Ecology 77:2,472-2,487. 

Thrush, S.F., J.E. Hewitt, V.J. Cummings, M.O. Green, G.A. Funnell, and M.R. Wilkinson. 

2000. The generality of field experiments: Interactions between local and broad-scale 

processes. Ecology 81:399-415. 

Thrush, S.F., J.E. Hewitt, G.A. Funnell, V.J. Cummings, J. Ellis, D. Schultz, D.Talley, and 

A. Norkko. 2001. Fishing disturbance and marine biodiversity: the role of habitat 

structure in simple soft-sediment systems. Mar. Ecol. Prog. Ser. 223:277-286. 

Thrush, S.F., J.E. Hewitt, P.M. Herman, and T. Ysebaert. 2005. Multi-scale analysis of 

species-environment relationships. Mar. Ecol. Prog. Ser. 302:13-26. 

Todd, C.D. 1998. Larval supply and recruitment of benthic invertebrates: do larvae always 

disperse as much as we believe? Hydrobiologia 375:1-21. 

Tolley, S.G. and A.K. Volety. 2005. The role of oysters in habitat use of oyster reefs by 

resident fishes and decapod crustaceans. J. Shellfish Res. 24:1,007-1,012. 

Tracy, B.A. and A. Cialone. 2004. Comparison of Gulf of Mexico Wave Information Studies 

(WIS) 2-G Hindcast with 3-G Hindcasting. Engineer Research and Development 

Center, Coastal and Hydraulics Laboratory, Waterways Experiment Station, 

Vicksburg, Mississippi, USA. 
MMS Study 2010-010 

158 

Trowbridge, J. H. 1995. A mechanism for the formation and maintenance of shore-oblique 

sand ridges on storm-dominated shelves. J. Geophys. Res. 100(C8):16,071-16,086. 

Turbeville, D.B. and G.A. Marsh. 1982. Benthic fauna of an offshore borrow area in Broward 

County, Florida. U.S. Army Corps of Engineers, Coastal Engineering Research 

Center, Miscellaneous Report 82-1. 43 pp. 

U.S. Army Corps of Engineers (USACE). 1989. Atlantic Coast of Maryland Hurricane 

Protection Project: Renourishment borrow study. U.S. Army Corps of Engineers, 

Baltimore District, Baltimore, MD. 

U.S. Army Corps of Engineers (USACE). 2008. Atlantic Coast of Maryland Shoreline 

Protection Project Final Supplemental Environmental Impact Statement General 

Reevaluation Study: Borrow Sites for 2010 – 2044. U.S. Army Corps of Engineers, 

Baltimore District, Baltimore, MD. 125 pp. + apps. 

Ullberg, J. and E. Ólafsson. 2004. Free-living marine nematodes actively choose habitat when 

descending from the water column. Mar. Ecol. Prog. Ser. 260:141-149. 

van Dalfsen, J.A., K. Essink, H. Toxvig Madsen, J. Birklund, J. Romero and M. Manzanera. 

2000. Differential response of macrozoobenthos to marine sand extraction in the 

North Sea and the Western Mediterranean. ICES J. Mar. Sci. 57:1,439-1,445. 

Van Dolah, R.F., D.R. Calder, and D.M. Knott. 1984. Effects of dredging and open-water 

disposal on benthic macroinvertebrates in a South Carolina estuary. Estuaries 

7:28-37. 

Van Dolah, R.F., B.J. Digre, P.T. Gayes, P. Donovan-Ealy, and M.W. Dowd. 1998. An 

evaluation of physical recovery rates in sand borrow sites used for beach 

nourishment projects in South Carolina. South Carolina Department of Natural 

Resources, Marine Resources Research Institute for the U.S. Department of the 

Interior, Minerals Management Service, Office of International Activities and Marine 

Minerals. 76 pp. + app. 

Van Hoey, G., K. Guilini, M. Rabaut, M. Vinex, and S. Degraer. 2008. Ecological implications 

of the presence of the tube-building polychaete Lanice conchilega on soft-bottom 

benthic ecosystems. Mar. Biol. 154:1,009-1,019. 

Vasslides, J.M. and K.W. Able. 2008. Importance of shoreface sand ridges as habitat for fishes 

off the northeastern coast of the United States. Fish. Bull. 106:93-107. 

Veer, H.W. van der, J.N. Bergman, and J.J. Beukema. 1985. Dredging activities in the Dutch 

Wadden Sea: Effects on macrobenthic infauna. Neth. J. Sea Res. 19:183-190. 

Virginia Institute of Marine Science (VIMS). 2000. Environmental Survey of Potential Sand 

Resource Sites Offshore Delaware and Maryland. Final Report to the U.S. 

Department of the Interior, Minerals Management Service, International Activities and 

Marine Minerals Division, Herndon, VA. OCS Study MMS 2000-055. 

Viscido, S.V., D.E. Stearns, and K.W. Able. 1997. Seasonal and spatial patterns of an 

epibenthic crustacean assemblage in northwest Atlantic Continental Shelf waters. 

Estuar. Coast. Shelf Sci. 45:377-392. 
MMS Study 2010-010 

159 

Voultsiadou, E., M. Pyrounaki, and C. Chintiroglou. 2007. The habitat engineering tunicate 

Microcosmus sabatieri Roule, 1885 and its associated peracarid epifauna. Estuar. 

Coast. Shelf Sci. 74:197-204. 

Walker, T.A. and G. O'Donnell. 1981. Observations on nitrate, phosphate and silicate in 

Cleveland Bay, Northern Queensland. Aust. J. Mar. Fresh. Res. 32:877-887. 

Wang, F. and P.M. Chapman. 1998. Biological implications of sulfide in sediment-a review 

focusing on sediment toxicity. Environ. Toxicol. Chem. 18:2,526-2,532. 

Wehrtmann, I.S. 1994. Larval production of the caridean shrimp, Crangon septemspinosa, in 

waters adjacent to Chesapeake Bay in relation to oceanographic conditions. 

Estuaries 17:509-518. 

Weissburg, M.J., M.C. Ferner, D.P. Pisut, and D.L. Smee. 2002. Ecological consequences of 

chemically mediated prey perception. J. Chem. Ecol. 28(10):1,953-1,970. 

West, H., J. Harrigan, and S. Pierce. 1984. Hybridization of two populations of a marine 

opisthobranch with different developmental patterns. Veliger 26:199-206. 

Weston, D.P. 1988. Macrobenthos-sediment relationships on the continental shelf off Cape 

Hatteras, North Carolina. Cont. Shelf Res. 8:267-286. 

Whitlatch, R.B. 1977. Seasonal changes in the benthic fauna inhabiting the intertidal sand and 

mud flats of Barnstable Harbor, MA. Biol. Bull. 152:275-294. 

Whitlatch, R.B., A.M. Lohrer, S.F. Thrush, R.D. Pridmore, J.E. Hewitt, V.J. Cummings, and 

R.N. Zajac. 1998. Scale-dependent benthic recolonization dynamics: Life 

stage-based dispersal and demographic consequences. Hydrobiologia 375:217-226. 

Wigley, R.L. and R.B. Theroux. 1981. Atlantic continental shelf and slope of the United 

States-macrobenthic invertebrate fauna of the Middle Atlantic Bight region-faunal 

composition and quantitative distribution. U.S. Geological Survey Professional Paper 

529-N. 198 pp. 

Wilber, D.H. and D.G. Clarke. 2001. Biological effects of suspended sediments: A review of 

suspended sediment impacts on fish and shellfish with relation to dredging activities 

in estuaries. N. Am. J. Fish. Mgmt. 21:855-875. 

Wilbur, P. and M. Stern. 1992. A re-examination of infaunal studies that accompany beach 

nourishment projects, pp. 242-257. In: New Directions in Beach Management: 

Proceedings of the 5th Annual National Conference on Beach Preservation 

Technology, Florida Shore and Beach Preservation Association, Tallahassee, FL. 

Wilcox, J.R. and H.P. Jeffries. 1974. Feeding habits of the sand shrimp Crangon 

septemspinosa. Biol. Bull. 146:424-434. 

Wilk, S.J., W.W. Morse, and L.L. Stehlik. 1990. Annual cycles of gonad-somatic indices as 

indicators of spawning activity for selected species of finfish collected from the New 

York Bight. Fish. Bull. 88:775-786. 

Winget, R.R., D. Maurer, and H. Seymour. 1974. Occurrence, size composition and sex ratio 

of the rock crab, Cancer irroratus Say and the spider crab, Libinia emarginata Leach 

in Delaware Bay. J. Nat. Hist. 8:199-205. 
MMS Study 2010-010 

160 

Witman, J. D., M.R. Patterson, and S.J. Genovese. 2004. Benthic-pelagic linkages in subtidal 

communities: influence of food subsidy by internal waves, pp. 133-153. In: G.A. 

Polis, M.E. Power, and G.R. Huxel, Food Webs at the Landscape Level. University of 

Chicago Press. 548 pp. 

Witting, D.A. and K.W. Able. 1993. Effects of body size on probability of predation for juvenile 

summer and winter flounder based on laboratory experiments. Fish. Bull. 

91:577-581. 

Witting, D.A. and K.W. Able. 1995. Predation by sevenspine bay shrimp, Crangon 

septemspinosa, on winter flounder, Pleuronectes americanus, during settlement: 

laboratory observations. Mar. Ecol. Prog. Ser. 123:23-31. 

Woodin, S.A. 1981. Disturbance and community structure in a shallow water sand flat. 

Ecology 62:1,052-1,066. 

Woodin, S.A., S.M. Lindsay, and D.S. Wethey. 1995. Process-Specific Recruitment Cues in 

Marine Sedimentary Systems. Biol. Bull. 189:49-58. 

Wright, D.G. 1977. Artificial islands in the Beaufort Sea: A review of potential impacts. 

Department of Fisheries and Environment, Winnipeg, Manitoba. 38 pp. 

Wu, R.S.S. and P.K.S. Shin. 1997. Sediment characteristics and colonization of soft-bottom 

benthos: A field manipulation experiment. Mar. Biol. 128:475-487. 

Zajac, R.N., R.B. Whitlatch, and S.F. Thrush. 1998. Recolonization and succession in 

soft-sediment infaunal communities: The spatial scale of controlling factors. 

Hydrobiologia 375:227-240. 

Zajac, R.N., R.S. Lewis, L.J. Poppe, D.C. Twichell, J. Vozarik, and M.L. DiGiacomo-Cohen. 

2003. Responses of infaunal populations to benthoscape structure and the potential 

importance of transition zones. Limnol. Oceanogr. 48:829-842. 

Zeng, C. and E. Naylor. 1996. Endogenous tidal rhythms of vertical migration in field collected 

Zoea-1 larvae of the shore crab Carcinus maenas: Implications for ebb tide offshore 

dispersal. Mar. Ecol. Prog. Ser. 132:71-82.