Prepared in cooperation with the U.S. National Park Service

Geologic Resource Evaluation of

Pu`uhonua O Ho–naunau National Historical Park, Hawai`i 

Part II: Benthic Habitat Mapping

U.S. Department of the Interior

U.S. Geological Survey

Scientific Investigations Report 2006-5258
Geologic Resource Evaluation of

Pu`uhonua O H–onaunau National Historical Park, 

Hawai`i

Part II: Benthic Habitat Mapping Volume

By Susan A. Cochran, Ann E. Gibbs, and Joshua B. Logan

Prepared in cooperation with the U.S. National Park Service

Scientific Investigations Report 2006–5258 

U.S. Department of the Interior

U.S. Geological Survey
U.S. Department of the Interior

DIRK KEMPTHORNE, Secretary

U.S. Geological Survey

P. Patrick Leahy, Acting Director

U.S. Geological Survey, Reston, Virginia: 2007

This report and any updates to it are available at: http://pubs.usgs.gov/sir/2006/5258

For product and ordering information:

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Telephone: 1-888-ASK-USGS

For more information on the USGS—the Federal source for science about the Earth, its natural and living resources, 

natural hazards, and the environment:

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Manuscript approved for publication, September 28, 2006

Text edited by Peter H. Stauffer

Layout by David R. Jones

Suggested citation:

Cochran, S.A., Gibbs, A.E., and Logan, J.B., 2007, Geologic resource evaluation of Pu`uhonua O H–onaunau National 

Historical Park, Hawai`i; Part II, Benthic habitat mapping: U.S. Geological Survey Scientific Investigations Report 

2006-5258, 20 p.

Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the 

U.S. Government.

Although this report is in the public domain, permission must be secured from the individual copyright owners to 

reproduce any copyrighted materials contained within this report.

Cover: Left, enlarged portion of benthic habitat map showing H–

onaunau Bay and Pu`uhonua O H–onaunau National Historical Park shoreline. Right, underwater photograph shows example of coral reef habitat on the Kona coast of Hawai`i.

iii

Contents

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

Data and methods..........................................................................................................................................2

Background data...................................................................................................................................2

Aerial photography......................................................................................................................2

SHOALS Lidar bathymetry..........................................................................................................2

Acquired data........................................................................................................................................2

Underwater video and still photography .................................................................................2

Benthic habitat mapping using GIS ...................................................................................................6

Classification scheme.................................................................................................................7

Accuracy assessment ...............................................................................................................8

Data archive...........................................................................................................................................8

Results .............................................................................................................................................................8

H–onaunau Bay (Subarea 1) ...............................................................................................................10

Pu`uhonua Point (Subarea 2)............................................................................................................12

Alahaka and Ki`ilae Bays (Subarea 3).............................................................................................12

Summary........................................................................................................................................................14

Accuracy of maps...............................................................................................................................14

Resource concerns ............................................................................................................................15

Acknowledgements.....................................................................................................................................15

References....................................................................................................................................................15

Appendix 

Detailed classification scheme .................................................................................................................17

Figures

1. Index map of the Island of Hawai`i showing the location of the three National Parks 

along the Kona coast. ...........................................................................................................................1

2. Flowchart illustrating methodology used to create Acquired Data habitat map. .......................2

3. Aerial photomosaic showing PUHO park boundary, study area, and place names 

mentioned in text....................................................................................................................................3

4. Aerial photomosaic of PUHO area overlaid with SHOALS bathymetry coverage. .....................4

5. Aerial photomosaic of PUHO area overlaid with locations of video transects, 

video point drops, and still camera photographs. ............................................................................5

6. Photograph of the Alyce C of Moloka'i heading out of M–a'alaea Harbor, Maui. ........................6

7. Photograph of SEAVIEWER camera system rigged to collect towed video. ...............................6

8. Photograph of shipboard system for navigation, recording of ship’s position, 

and feature annotation..........................................................................................................................6

9. Schematic diagram showing the generalized cross-shelf coral reef zonation...........................8

10. Three-dimensional perspective view of area of study, including Pu`uhonua O H–onaunau 

National Historical Park, H–onaunau Bay, Pu`uhonua Point, and Alahaka and Ki`ilae Bays, 

showing geographic reef zonation......................................................................................................8

11. Classification map of Pu`uhonua O H–onaunau National Historical Park 

showing dominant structure.................................................................................................................9
iv

12. Aerial photomosaic of subarea 1 (H–onaunau Bay), overlaid with benthic habitat classes .....10

13. Aerial photomosaic of PUHO showing shaded relief bathymetry and cross-section 

profiles of the reef ................................................................................................................................11

14. Aerial photomosaic of subarea 2 (Pu`uhonua Point), overlaid with benthic 

habitat classes ......................................................................................................................................12

15. Aerial photomosaic of subarea 3 (Alahaka and Ki`ilae Bays), overlaid with benthic 

habitat classes ......................................................................................................................................13

16. Pie chart showing the breakdown of benthic habitats of the PUHO study area.......................14

17. Graph showing major biological covers with depth at PUHO.......................................................14

Tables

1. Major structure (substrate) types with dominant structure subdivisions....................................7

2. Major biologic cover classes...............................................................................................................7

3. Percent cover classes...........................................................................................................................7

4. Geomorphic zones of coral reef ecosystems....................................................................................7

5. Matrix showing accuracy assessment for the major biological cover classes........................15
Geologic Resource Evaluation of

Pu`uhonua H–onaunau National Historic Park, Hawai`i 

Part II: Benthic Habitat Mapping

By Susan A. Cochran, Ann E. Gibbs, and Joshua B. Logan

downslope of any development in the park are of concern to 

management. The area mapped for this report extends from 

Hönaunau Bay, around Pu`uhonua Point, to Ki`ilae Bay and 

the south park boundary and from the shoreline to depths of 

approximately 40 m (130 ft), where the shelf drops off to a 

sand-covered bottom. 

Pu`uhonua O Hönaunau National Historical Park lies 

within the nearly 850-km2 Ki`ilae watershed, which begins at 

the crest of Mauna Loa. The Ki`ilae Watercourse runs through 

the southern area of the park and empties into Ki`ilae Bay, but 

only during periods of extreme rainfall. 

The waters of Keone`ele Cove, the ancient royal canoe 

landing at PUHO, while not formally under NPS jurisdiction, 

are managed by the park under an agreement with the State 

of Hawai`i. This small embayment is a known haven for sea 

turtles, which are often found sunning themselves on the nearIntroduction

In cooperation with the U.S. National Park Service 

(NPS), the U.S. Geological Survey (USGS) has mapped the 

underwater environment in and adjacent to three parks along 

the Kona coast on the island of Hawai`i (fig. 1). This report 

is the second of two produced for the NPS on the geologic 

resource evaluation of of Pu`uhonua O Hönaunau National 

Historical Park (PUHO) and presents the results of benthic 

habitat mapping of the offshore waters for PUHO. See Part I 

(Richmond and others, 200) for an overview of the regional 

geology, local volcanics, and a detailed description of coastal 

landforms in the park.

Pu`uhonua O Hönaunau National Historical Park 

boundaries extend only to the mean high tide line and do not 

officially include the marine environment. However, impacts 

Pacific

Ocean

Hawaiian Islands

Hawai`i Hawai`i

MAP

AREA

20° N 

19°30'

19°

156° W 155°30' 155°

Kilometers

0 50

Pu`ukohol–a Heiau

National Historic Site

(PUHE)

Kaloko-Honok–ohau

National Historical Park

(KAHO)

Pu`uhonua H–

onaunau

National Historical Park

(PUHO)

Hilo

Kailua-Kona

Mauna Loa

Mauna Kea

Hualalai

Kohala

Figure 1. Index map of the Island of Hawai`i 

showing the location of the three National 

Parks along the Kona coast. Volcano names 

are shown in white.
 Pu`uhonua O H–

onaunau National Historical Park, Hawai`i—Benthic Habitat Mapping

shore volcanic platform. Impacts to this area include frequent 

visits by scuba divers and snorkelers to Hönaunau Bay and a 

small boat ramp located just to the north of Keone`ele Cove.

Data and Methods

A standard for characterization of coral-reef environments was first implemented by the National Oceanic and 

Atmospheric Administration (NOAA) for mapping the Florida 

Keys (Rohman and Monaco, 2005) and Puerto Rico and the 

Virgin Islands (Kendall and others, 2001). This standard for 

mapping coral reefs in the United States and its territories 

describes benthic habitats on the basis of their sea-floor geomorphology, geographic zonation, and biological cover.

In this study, the benthic-habitat classification maps were 

created using the standards established by NOAA but at a finer 

scale (minimum mapping unit of 100 m2

 versus 1 acre) and 

with additional data sources, including existing color aerial 

photography, Scanning Hydrographic Operational Airborne 

Lidar Survey (SHOALS) bathymetric data, georeferenced 

underwater video, and still photography. The maps were generated using both ArcView and ArcMap Geographic Information System (GIS) software by ESRI (http://www.esri.com), 

and a statistical analysis of accuracy of the resultant maps was 

performed. The flowchart in figure 2 illustrates the complete 

methodology.

Background Data

Aerial Photography

The National Park Service provided the aerial imagery 

used as a base layer in this mapping effort. True-color aerial 

photographs were collected in June 2000 by NOAA. These 

images were geometrically registered to true map coordinates 

and mosaicked by the Pacific Disaster Center, resulting in 

an orthorectified digital mosaic with a resolution of 1 meter 

per pixel (fig. 3). For further details on NOAA aerial photography for Hawai`i see http://ccma.nos.noaa.gov/products/

biogeography/hawaii_cd/htm/mosaic.htm. 

SHOALS Lidar Bathymetry

High-resolution SHOALS bathymetry point data collected in 2000 by the U.S. Army Corps of Engineers (USACE) 

were obtained and converted to a raster surface using ESRI’s 

‘GRID’ function. The bathymetric data have an average 

horizontal point spacing of 4 m (± ~3 m) and a vertical resolution of ± 0.15 m, with a maximum depth penetration of about 

38 m in the study area. Sparse data near the coastline and 

throughout the central part of the study area around Pu`uhonua 

Point were filled in by interpolating between the coastline and 

shoreward edge of the SHOALS bathymetry. However, there 

is still a data gap in Alahaka Bay (fig. 4). Isobaths, hillshades, 

and slope maps were derived from this dataset using standard 

ArcMap functions and used to assist in the interpretation. For 

further details regarding SHOALS data, see http://shoals.sam.

usace.army.mil.

Acquired Data

Underwater Video and Still Photography

More than 6 trackline kilometers of underwater video 

footage (29 towed lines plus 1 snorkel), and more than 100 

still-camera photographs and video-camera point drops were 

collected during two field surveys between April 2004 and 

August 2004 to assist in interpretation of the aerial photography and lidar bathymetry (fig. 5). Navigation and other information regarding these surveys are available online at http://

walrus.wr.usgs.gov/infobank/a/a204hw/html/a-2-04-hw.meta.

html, and http://walrus.wr.usgs.gov/infobank/a/a604hw/html/

Underwater photos

Video tows

SHOALS bathymetry

Base layers

and

in situ observations

Aerial Photography

NOAA random points

Field check

 observations

USGS random points

Interpretation

using ArcView 3.2a

and Habitat Digitizing

extension

Draft Map

Final map and

written report

Accuracy

assessment

and

matrix calculated

Mapped

polygon

correct?

Make corrections to

mapped polygons

YES

NO

Figure 2. Flowchart illustrating methodology used to create 

Acquired Data habitat map. See text for complete description.
Data and Methods 

Figure 3. Aerial photomosaic showing PUHO park boundary, study area, and place names mentioned in text.

19°24’30”

19°25’30”N

19°25’

155°55’ W 155°54’30”

Kilometers

0 1

Miana Point

Pu`uhonua Point

Ki`ilae

Watercourse

Keone`ele

Cove

Hnaunau Bay

Alahaka Bay

Ki`ilae Bay

Keanai`e Pali

Park boundary

Study area

Pu`uhonua O H–onaunau

National Historical Park
 Pu`uhonua O H–

onaunau National Historical Park, Hawai`i—Benthic Habitat Mapping

Figure 4. Aerial photomosaic of PUHO area overlaid with SHOALS bathymetry coverage.

19°24’30”

19°25’30” N

19°25’

155°55’ W 155°54’30”

Kilometers

Contour interval 5 m

0 1

Hnaunau Bay

Alahaka Bay

Ki`ilae Bay

Park boundary

Kilometers

Contour interval 5 meters

0 1

0

SHOALS bathymetry,

in meters

38

Pu`uhonua O H–onaunau

National Historical Park
Data and Methods 

Figure 5. Aerial photomosaic of PUHO area overlaid with locations of video transects, video point drops, and still camera photographs.

19°24’30”

19°25’30” N

19°25’

155°55’ W 155°54’30”

Kilometers

0 1

Hnaunau Bay

Alahaka Bay

Ki`ilae Bay

Park boundary

Video transects

Video drops

Photo locations

Pu`uhonua O H–onaunau

National Historical Park
 Pu`uhonua O H–

onaunau National Historical Park, Hawai`i—Benthic Habitat Mapping

a-6-04-hw.meta.html. Several types of camera systems and 

collection methods were used. During diving and snorkeling, 

still images were collected using a hand-held digital camera 

(Sony DSC-P5 or Canon PowerShot S-400). 

Video imagery was also obtained by towing a camera 

off the Alyce C, a 32-ft vessel operated by Capt. Joe Reich of 

Moloka`i (fig. 6), and a 13-ft motorboat owned by the NPS. 

The camera system used was a watertight video camera illuminated with a light-emitting diode (LED) ring designed by 

SeaViewer Underwater Video Systems (http://www.seaviewer.

com). The camera was mounted in a small aluminum handheld frame with a rear-mounted plastic fin (fig. 7). Live video 

was viewed in a shipboard laboratory on a standard CRT 

monitor and recorded directly to miniDV tape. Time, date, 

location, and ship speed were overlaid on the video using the 

Sea-Trak global positioning system (GPS) method, also developed by the SeaViewer company.

Simultaneous navigation, recording of ship position, and 

feature annotation were conducted in real time using Red Hen 

Systems’ (http://www.redhensystems.com) VMS200 hardware 

and MediaMapper software on a PC laptop (fig. 8). Location data were recorded using a hand-held, WAAS-enabled, 

Garmin (http://www.garmin.com) GPS76 receiver. The stated 

horizontal accuracy of the Garmin GPS76 is better than 3 m 

when receiving WAAS corrections. The VMS200 transmitted 

NMEA-formatted GPS data at two second intervals to the first 

audio channel of the video tape. A database was simultaneously created by MediaMapper to cross-reference the GPS 

locations and video time codes. This technique allowed for 

navigation and video to be viewed real-time and the location 

of features of interest and comments (for example, start/end of 

lines, substrate types) to be added to the database during data 

collection. Back in the lab, this technique allowed rapid random access to the original video by selecting locations along 

the navigation trackline within MediaMapper and GeoVideo 

(an extension developed by Red Hen Systems for integration 

with the ESRI ArcMap platform) software packages. Video 

could be interactively queried and geographically referenced 

feature annotations added to the database.

Benthic Habitat Mapping using GIS

Digital benthic habitat maps were created using ESRI’s 

ArcViewGIS v.3.2 software with a habitat digitizing extension 

created by NOAA (to download the extension see http://ccma.

nos.noaa.gov/products/biogeography/hawaii_cd/htm/digitize.

htm). The habitat digitizing extension allows users to delineate habitat areas and assign attributes to the habitat polygons 

based on a predetermined classification scheme using a pointand-click menu system.

We digitally delineated more than 70 polygons, covering 

nearly 1 km2

, by interpreting features seen in both the aerial 

photographs and SHOALS bathymetry layers, with additional 

input from other data. A minimum mapping unit (MMU) of 

100 m2

 was used; however, smaller features were mapped if 

Figure 6. Photograph of the Alyce C of Moloka'i heading out of 

M–a'alaea Harbor, Maui.

Figure 7. Photograph of SEAVIEWER camera system rigged to 

collect towed video.

Figure 8. Photograph of shipboard system for navigation, 

recording of ship’s position, and feature annotation.
Data and Methods   

they carried habitat significance (for example, an individual 

coral colony 2 m in diameter located in an otherwise uncolonized area). 

Classification Scheme

The classification scheme is based on a scheme established by NOAA’s biogeography benthic habitat mapping 

program in 2002 (Coyne and others, 2003) for the main 

eight Hawaiian islands, and subsequently revised in 2004 

(National Oceanic and Atmospheric Administration National 

Centers for Coastal Ocean Science, 2005). Developed with 

input from coral reef scientists, managers, local experts, 

and others, the hierarchal scheme allows users to expand or 

collapse the level of thematic detail as necessary. As stated 

above, we are using NOAA’s definition of benthic habitats 

and their classification scheme as a starting point to provide 

continuity to the coral reef scientific community. However, 

we have made additional modifications to the classification 

scheme to better reflect the benthic habitats and geologic 

substrates found along the Kona coast.

The classification scheme uses five basic attributes to 

describe each polygon on the benthic habitat map: (1) the 

major structure or underlying substrate, (2) the dominant 

structure, (3) the major biologic cover found on the substrate, (4) the percentage of major biological cover, and (5) 

the geographic zone indicating the location of the habitat. 

The structure combination with the overlying biologic cover 

is referred to as a “habitat.” Majority rules—if a polygon 

includes two or more substrate or coverage types, the polygon is identified with the dominant one. 

Four major structure types are further subdivided into 

fifteen dominant structures (table 1). Ten major biologic 

cover types are also modified by the percent of coverage (tables 2 and 3). The classification scheme allows for 

any biologic cover to be found on any structure/substrate, 

although many combinations are unlikely (for example, coral 

on sand, or emergent vegetation on spur-and-groove). Less 

than 10 percent cover of any type is equivalent to 90 –100 

percent uncolonized; therefore 0 –10 percent cover is not 

used. Each polygon is coded with a 4-digit UNIQUEID attribute that reflects the combination of the individual habitat 

components (major structure, dominant structure, major 

biologic cover, and percent cover).

The fifth attribute, zone, refers only to a habitat community’s location within the coral reef ecosystem and does 

not indicate the substrate or biological cover type (fig. 9). 

Eleven zones correspond to typical reef geomorphology 

found in current literature (table 4). An additional dredged 

zone has been added to include those areas where anthropogenic change has occurred (for example, harbors and 

manmade channels). Detailed descriptions of habitats and 

zones, including example photographs, may be found in the 

appendix.

Table 1. Major structure (substrate) types with dominant 

structure subdivisions. 

[Numbers represent UNIQUEID identifier.]

Major Structure Dominant Structure

1 Unconsolidated 

Sediment

1 Mud

2 Sand

2 Reef and 

Hardbottom

1 Aggregate Reef

2 Spur-and-Groove

3 Individual Patch Reef

4 Aggregated Patch Reef

5 Volcanic Pavement with 10 –<50% 

Rocks/Boulders

6 Volcanic Pavement

7 Volcanic Pavement with >50% Rocks/

Boulders

8 Volcanic Pavement with Sand Channels

9 Reef Rubble

3 Other 0 Unknown

1 Land

2 Artificial

3 Artificial/Historical

9 Unknown 0 Unknown

Table 2. Major biologic 

cover classes. 

[Numbers represent 

UNIQUEID identifier.]

Table 3. Percent 

cover classes

[Numbers represent 

UNIQUEID identifier.]

Major Biological Cover Percent Cover

0 Unknown 0 Unknown

1 Uncolonized 2 10–<50%

2 Macroalgae 3 50 –<90%

3 Seagrass 4 90 –100%

4 Coralline Algae

5 Coral

6 Turf

7 Emergent Vegetation

8 Mangrove

9 Octocoral

Table 4. Geomorphic zones of 

coral reef ecosystems.

Zone

Land

Shoreline/Intertidal

Vertical Wall

Lagoon

Back Reef (with Lagoon)

Reef Flat (without Lagoon)

Reef Crest

Fore Reef

Bank/Shelf

Bank/Shelf Escarpment

Channel

Dredged
   Pu`uhonua O H–

onaunau National Historical Park, Hawai`i—Benthic Habitat Mapping

Accuracy Assessment 

The validity, or usefulness, of any classification or interpretation may be determined with an accuracy assessment, 

which compares the interpretation with what is actually found 

in the field. In this project, the benthic habitat map’s overall 

accuracy and its accuracy from both the user and producer 

points of view were determined. 

Overall accuracy indicates which points on the map 

are classified correctly according to a field check (Lillesand 

and Keifer, 1994). Producer accuracy indicates how well the 

map producer classified the different cover types (that is, the 

number of points on the map labeled correctly). User accuracy 

indicates the probability that a point in a given class is actually 

represented by that class in the field (that is, which mapped 

areas are actually what the map says they are).

This mapping project was performed concurrently with 

similar projects at two other National Parks along the Kona 

coast, Kaloko-Honoköhau National Historical Park (KAHO) 

and Pu`ukoholä Heiau National Historic Site (PUHE). A 

combination of field check data from all three parks was 

used to measure the accuracy of the PUHE benthic habitat 

map. Nearly 190 randomly generated sample points were 

visited by third-party coral reef research biologists from the 

University of Hawai`i who are highly familiar with the classification scheme. In addition, more than 50 sampling points 

from the NOAA database (http://ccma.nos.noaa.gov/products/

biogeography/hawaii_cd/htm/aap.htm) were used in the accuracy assessment.

Once the accuracy assessment calculations were completed, any misinterpreted polygons identified were corrected, 

thus increasing the percent accuracy of the final map.

Data Archive

Underwater video footage, photographs, and associated 

shapefiles have been transferred to DVD. One complete set 

will be held in the USGS archives (see http://walrus.wr.usgs.

gov/infobank/a/a204hw/html/a-2-04-hw.meta.html and http://

walrus.wr.usgs.gov/infobank/a/a604hw/html/a-6-04-hw.meta.

html to view list of analog holdings) and the other will be presented to the National Park Service to accompany this report. 

This report and project shapefiles are also available online 

(http://pubs.usgs.gov/sir/2006/5258).

Results

The reef zonation off Pu`uhonua O Hönaunau National 

Historical Park (PUHO) is simple in the sense that it consists 

solely of a sloping volcanic shelf platform that begins at the 

shoreline and descends out to a sand-covered bottom towards 

the deep ocean (fig. 10). There is no reef crest separating a 

back reef from a fore reef, and no spur-and-groove structures. 

Figure 9. Schematic diagram showing the generalized crossshelf coral reef zonation. Not shown: land, channel, dredged, or 

vertical wall (modified from Kendall and others, 2004). Detailed 

descriptions of the zones are given in the appendix.

Figure 10. Three-dimensional perspective view of area of study, including Pu`uhonua O H–onaunau National Historical Park, H–onaunau 

Bay, Pu`uhonua Point, and Alahaka and Ki`ilae Bays, showing geographic reef zonation. Areas of black on reef shelf indicate lack of 

bathymetric data. View is to the northeast. Approximate distance along the bottom of the figure is 2.5 km.

Mean high tide line

Spring low tide line

Shoreline/

Intertidal

Reef flat Reef

crest Fore reef

Shelf

Shelf

escarpment

vertical exaggeration = 2

Ki`ilae Bay

Alahaka Bay

Hnaunau Bay

Pu`uhonua Point

Park boundary

Shelf

Shoreline/intertidal

Pu`uhonua O H–onaunau

National Historical Park
Results   

Figure 11. Classification map of Pu`uhonua O H–onaunau National Historical Park showing dominant 

structure. The study area is divided into three subareas on the basis of their predominant benthic 

habitats and structure: (1) H–onaunau Bay, (2) Pu`uhonua Point, and (3) Alahaka/Ki`ilae Bays. See text for 

detailed descriptions of each of these subareas.

19°24’30”

19°25’30” N

19°25’

155°55’ W 155°54’30”

Kilometers

0 1

Hnaunau

Bay

Alahaka

Bay

Ki`ilae

Bay

Subarea 1

H–onaunau Bay

Subarea 2

Pu`uhonua Point 

Subarea 3

Alahaka/

Ki`ilae Bays 

Aggregate reef

Reef rubble

Sand

Volcanic pavement, >50%

 rocks and boulders

Volcanic pavement, 10–50%

 rocks and boulders

Volcanic pavement

Dominant Structure

Pu`uhonua

Point

Park boundary

Pu`uhonua O H–onaunau

National Historical Park
10 Pu`uhonua O H–

onaunau National Historical Park, Hawai`i—Benthic Habitat Mapping

The nearshore intertidal zone ranges in width from narrow 

rocky areas near the base of sea cliffs, to wide flat platforms 

around Keone`ele Cove, which are used as haul-out areas for 

basking sea turtles.

Although the reef zonation at PUHO is simple, the study 

area can be divided into three distinct subareas based upon 

their predominant benthic habitats and structure (fig. 11). Subarea 1 (Hönaunau Bay), at the northern shoreline of PUHO, 

is a deep embayment with a well-developed coral community. 

Subarea 2 (Pu`uhonua Point), along the middle of the park, is 

exposed to high wave energy, and coral growth is limited. Subarea 3 (Alahaka and Ki`ilae Bays), at the south boundary, has 

variable coral cover on the volcanic pavement. Each of these 

subareas is described in detail below.

H–onaunau Bay (Subarea 1)

The north boundary of PUHO lies along the south shore 

of Hönaunau Bay. A well-developed coral reef environment 

has formed within Hönaunau Bay (fig. 12), and easy accessibility makes it a favorite spot for recreational activities, including swimming, SCUBA diving, and snorkeling. A nearby 

public boat ramp allows fishermen quick access to the south 

Kona coastline.

The northern half of Hönaunau Bay is characterized by 

a narrow (20–50 m) reef environment that abruptly drops off 

to the sandy bottom in the middle of the bay (fig. 13, transect 

A–A'). Near the mouth of the bay and along the southern half, 

the reef platform is much broader (120 –150 m), yet it drops 

off to the bottom just as steeply (fig. 13, transect B–B').

A small (2– 4 m high) sea cliff along the north shore of 

Hönaunau Bay drops down into the shoreline zone. At the base 

of the sea cliff is uncolonized volcanic pavement. Around –3 

m (10 ft below the surface of the water) the volcanic pavement 

becomes scattered with rocks and occasional large boulders and is dotted with small colonies of mostly Pocillopora 

meandrina and Porites sp. The volcanic pavement is relatively 

horizontal (~5° slope) between –3 m (–10 ft) and –15 m (–50 

ft). Around –15 m the volcanic slope drops off at a 35°– 40° 

angle into a sand-covered bottom in the middle of the bay. 

This steep slope is characterized by a lush (50–<90 percent 

coral cover) aggregate reef that is covered predominantly with 

Figure 12. Aerial photomosaic of subarea 1(H–onaunau Bay), overlaid with benthic habitat classes. 

See text for discussion.

19°25’30” N

155°55’ W

Miana Point

Pu`uhonua Point

Keone`ele

Cove

Hnaunau

Bay

Meters

0 200 400

Sand, uncolonized

Aggregate reef, 10–<50% coral

Aggregate reef, 50–<90% coral

Volcanic pavement,10–50% rocks 

and boulders, uncolonized

Volcanic pavement, 10–50% rocks 

and boulders, 10–<50% coral

Volcanic pavement, uncolonized

Volcanic pavement, 10–<50% coral

Volcanic pavement, >50% rocks and 

boulders, 10–<50% coral

Reef rubble, uncolonized

Benthic Habitat Classes

Park boundary

Pu`uhonua O H–onaunau

National Historical Park
Results 11

Porites sp. Large, lobate colonies (for example, Porites lobata) 

are found near the upper edge, transitioning into more fingershaped colonies (for example, Porites compressa) in deeper 

water. Farther seaward, the upper depth limit of this lush coral 

zone trends deeper, where it is less exposed to high wave 

conditions, until it terminates at Mïana Point. Outside Mïana 

Point, where the sloping volcanic platform is exposed to more 

energetic waves, there is no aggregate reef, but there are a 

greater number of rocks and boulders. Presumably the higher 

wave energy outside the point is strong enough to dislodge 

more rocks from the surrounding sea cliff than farther within 

Hönaunau Bay. North of Mïana Point this sparsely covered 

rocky pavement continues to around –38 m (–125 ft), the 

depth limit of this survey. 

The volcanic platform in the southern half of Hönaunau 

Bay is much broader than in the northern half of the bay. The 

nearshore intertidal zone consists of a nearly horizontal uncolonized volcanic platform. The uneven surface is often exposed 

at low tides, leaving behind tide pools. Sea turtles often bask 

on the warm platform around the PUHO boundary, especially 

near Keone`ele Cove. Approximately 40 m from shore, the 

shallow intertidal volcanic platform drops off to another nearly 

horizontal platform around –5 m (–16 ft). Scattered corals 

grow directly on this part of the volcanic pavement, becoming 

more and more dense in deeper water. With the exception of a 

few sand patches, by –10 m (–33 ft) the coral is dense enough 

to form an aggregate reef complex, which then extends to the 

edge of the platform and deeper. As in the northern half of the 

bay, around –15 m (–50 ft) the volcanic slope drops off sharply 

at a 35°– 40° angle. The aggregate reef follows the slope all 

the way to the sand-covered bottom in the middle of the bay. 

Rapid assessments of benthic coverage show an average coral 

cover of 67.0 percent in this area of Hönaunau Bay (Rodgers 

and others, 2004). Farther seaward along the south edge of 

the bay towards Pu`uhonua Point, the upper depth limit of the 

reef complex lies deeper and deeper, where it is less exposed 

to high wave conditions. Near the point, where the upper slope 

and shallower platform are exposed to higher waves, the volcanic pavement is scattered with numerous rocks and boulders 

and occasionally dotted with smaller wave-resistant corals.

We observed numerous ground-water seeps along the 

entire shoreline of Hönaunau Bay. These were apparent during 

snorkel surveys by the distortion in the water and by changes 

in water temperature. Although no quantitative measurements 

Figure 13. Aerial photomosaic of PUHO showing shaded relief bathymetry and cross-section profiles of the reef. 

See text for details.

19°24'30”

19°25'30”N 

155°55' W 155°54'30”

Kilometers

0 1

Pu`uhonua Point

Hnaunau

Bay

Alahaka Bay

Pu`uhonua O H−onaunau

National Historical Park

A

A‘

B‘

B

C

C‘

D D‘

0

0

20

40

50 100

Distance, in meters

Depth, in meters

0

0

20

40

50 100 150 200 250

Slope = 38.6°

Slope = 35.3°

0

0

20

40

50 100 150 200 250

Slope = 30.1°

Sand bottom

Sea

clift

0

0

20

40

50 100 150 200 250

A A’

B B’

C C’

D D’
12  Pu`uhonua O H–

onaunau National Historical Park, Hawai`i—Benthic Habitat Mapping

were taken along the shoreline, data were collected with a 

CTD (conductivity/temperature/depth) recorder from a boat 

in the deeper waters of the bay. These measurements were collected as part of a greater study by the USGS regarding groundwater flux along the Kona coast (Grossman and others, 2006).

Pu`uhonua Point (Subarea 2)

Pu`uhonua Point, a broad volcanic platform formed by 

flows from Mauna Loa, composes the central part of PUHO 

National Historical Park. The submerged part of this volcanic 

platform extends offshore approximately 100–300 m at its 

widest point (fig. 13, transect C–C'). Between the shoreline 

and –15 m (–50 ft), the platform slopes gently (5°–10°) seaward. At approximately –15 m, the platform drops off sharply 

at a 30°–35° slope to the offshore sandy bottom. The point is 

exposed to high wave energy, and is covered with scattered 

rocks and boulders, sparse coral cover, and many bare or 

sand-covered patches (fig. 14). Rapid assessments of benthic 

coverage, performed concurrently by marine biologists from 

the University of Hawai`i, show an average coral cover of 21.4 

percent in this area (Rodgers and others, 2004). The shoreline/intertidal zone, where the wave energy is most extreme, 

is uncolonized volcanic pavement. In the leeward, southern 

part of Pu`uhonua Point, where there is less wave energy, a 

shore-parallel band of aggregate reef (mostly Porites sp.) is 

found between –10 and –20 m (–33 and –66 ft) on the sloping 

platform. 

Alahaka and Ki`ilae Bays (Subarea 3)

The southern shoreline of PUHO lies along Alahaka 

and Ki`ilae Bays, which are separated by the southernmost 

extension of the crescent-shaped Keanae`e Pali. The narrow 

shoreline/intertidal zone of Alahaka Bay is uncolonized volcanic pavement (fig. 15). From the shoreline to approximately 

–10 m (–33 ft) the volcanic pavement is strewn with rocks and 

boulders, both uncolonized and sparsely covered with coral. 

By contrast, Ki`ilae Bay consists of uncolonized volcanic 

pavement near the shoreline at the base of a small (5 m) sea 

Figure 14. Aerial photomosaic of subarea 2 (Pu`uhonua Point), overlaid with benthic habitat classes. 

See text for discussion.

19°25’ N

155°55’ W 155°54’30”

Pu`uhonua Point

Alahaka Bay

Meters

0 200 400

Benthic Habitat Classes

Park boundary

Pu`uhonua O H–onaunau

National Historical Park

Sand, uncolonized

Aggregate reef, 10–<50% coral

Aggregate reef, 50–<90% coral

Volcanic pavement,10–50% rocks 

and boulders, uncolonized

Volcanic pavement, 10–50% rocks 

and boulders, 10–<50% coral

Volcanic pavement, uncolonized

Volcanic pavement, 10–<50% coral

Volcanic pavement, >50% rocks 

and boulders, 10–<50% coral

Reef rubble, uncolonized
Results 13

cliff, and lacks the rocks and boulders. A shore-parallel band 

of aggregate reef covered with 50–<90 percent coral (mostly 

Porites sp.) is found offshore of both bays between –12 and 

-30 m (– 40 and –100 ft) before the volcanic slope drops off 

into a sandy bottom. Rapid assessments of benthic coverage 

show an average coral cover of 48.9 percent in Alahaka Bay 

(Rodgers and others, 2004).

As in subarea 1 (Hönaunau Bay), we observed some 

ground-water seeps in the shallow areas of Alahaka and 

Ki`ilae Bays. Again, no quantitative measurements were 

taken along the shoreline during our snorkel surveys, yet data 

were collected with a CTD (conductivity/temperature/depth) 

recorder from a boat offshore. See Grossman and others 

(2006) for results of ground-water mapping.

Figure 15. Aerial photomosaic of subarea 3 (Alahaka and Ki`ilae Bays), overlaid with benthic habitat 

classes. See text for discussion.

19°24’30”

19°24’45” N

155°54’30” W

Alahaka Bay

Ki`ilae Bay

Meters

0 200 400

Benthic Habitat Classes

Park boundary

Pu`uhonua O H–onaunau

National Historical Park

Sand, uncolonized

Aggregate reef, 50–<90% coral

Volcanic pavement,10–50% rocks 

and boulders, uncolonized

Volcanic pavement, 10–50% rocks 

and boulders, 10–<50% coral

Volcanic pavement, uncolonized

Volcanic pavement, 10–<50% coral

Reef rubble, uncolonized
14  Pu`uhonua O H–

onaunau National Historical Park, Hawai`i—Benthic Habitat Mapping

Summary

The three subareas in this mapping project, Hönaunau 

Bay, Pu`uhonua Point, and Alahaka and Ki`ilae Bays, are 

distinctly different in their major benthic habitats. Wave 

energy appears to be a dominant control. Sheltered Hönaunau Bay has a lush coral reef environment both in the shallows and at deeper depths; Pu`uhonua Point is a sparsely 

covered volcanic platform where coral growth is apparently 

limited by wave energy; Alahaka and Ki`ilae Bays have 

limited corals growing in patches on rocky pavement near the 

shoreline, but have an aggregate reef found between –12 and 

–30 m (– 40 and –100 ft).

Of the nearly 1 km2 that was mapped for this portion of 

the project, 25 percent (221,083 m2) was classified as volcanic pavement with 10–<50 percent scattered rocks and boulders covered with 10 –<50 percent coral (fig. 16). Although 

Hönaunau Bay itself boasts one of the lushest coral reef 

environments along the Kona coast, the high percentage of 

sparsely covered, rocky volcanic pavement shown here is due 

to the inclusion of the wave-swept platform of Pu`uhonua 

Point in the study area. The next predominant benthic habitats in the study area were uncolonized volcanic pavement 

(24 percent), and aggregate reef with 50–<90 percent coral 

(19 percent). The highly colonized aggregate reef is mostly 

found between –15 to –25 m (–50 to –82 ft) (fig. 17). Sparse 

coral cover is found throughout the study area, but is mainly 

focused between –5 m and –15 m (–16 and –25 ft). From the 

shoreline to –10 m (–33 ft) the uncolonized areas are bare 

volcanic pavement, whereas from –20 to –35 m (– 66 to –115 

ft) the uncolonized areas are sand.

Accuracy of Maps

An accuracy assessment was performed for the major 

biological covers (table 5). A total of 241 randomly selected 

points for all three National Parks (PUHO, KAHO, and 

PUHE) were checked in the field. The overall accuracy of 

91.29 percent (with a 95-percent confidence interval of ± 

1.1) indicates which points on the map were classified correctly according to the field check. Producer’s accuracy is an 

indication of how well we correctly identified pixels for each 

different class (for example, coral = 96.39 percent, uncolonized = 75.00 percent). User’s accuracy is the probability that, 

for a classified pixel on the map, the map user will actually 

find that class in the field (for example, coral = 94.67 percent, 

octocoral = 60.00 percent). A tau coefficient of 0.9005 was 

calculated as described by Ma and Redmond (1995), and indicates that 90.05 percent more points were classified correctly 

than would be expected by chance alone. 

After accuracy assessment calculations were performed, 

any misinterpreted polygons identified on the Kona coast reef 

maps were corrected using the field check data, thus increasing the overall accuracy of the final maps to greater than 

91.29 percent.

Figure 16. Pie chart showing the breakdown of benthic habitats of 

the PUHO study area. More than 0.2 km2

 (25 percent) of the study 

area was classified as volcanic pavement with 10–<50 percent 

scattered rocks and boulders covered with 10–<50 percent coral. 

The next predominant benthic habitats in the study area were 

uncolonized volcanic pavement (24 percent) and aggregate reef 

with 50–<90 percent coral (20 percent).

Figure 17. Graph showing major biological covers with depth at 

PUHO. Sparse coral cover is found throughout the study area, but 

is mainly focused between –5 m and –15 m.

Aggregate reef

10–<50% coral

18,198 m2

2%

Aggregate reef

50–<90% coral

171,877 m2

20%

Uncolonized

sand

146,157

17%

Uncolonized reef rubble

13,999 m2

2%

Volcanic

pavement

10–50% rocks/boulders

10–<50% coral

217,148 m2

24%

Volcanic pavement

>50% rocks/boulders

10–<50% coral

37,674 m2

4%

Volcanic

pavement

10–<50% coral

46,954 m2

5%

Uncolonized

volcanic pavement

10–50% rocks/boulders

26,052 m2

3%

Uncolonized

volcanic pavement

203,160

23%

0 20 40 60 80 100

Areal percent

0

5

10

15

20

25

30

35

40

Depth,

in meters

Biological covers

10–<50% coral

50–<90% coral

Uncolonized
Summary 15

Resource concerns

No submerged archeological features are known to exist 

offshore of Pu`uhonua O Hönaunau National Historical Park, 

nor did we find evidence of any during our video transects. 

The main concern for park management should be groundwater flow to the nearshore environment. Although sedimentation from the uplands does not appear to be a problem at this 

time, other particles and nutrients may affect the health of the 

ecosystem. Any future projects should take into account the 

effects to the ground-water system and plan accordingly.

Acknowledgements

The authors wish to thank Pat Chavez and his group 

from the USGS in Flagstaff for coordinating our acquisition of the SHOALS bathymetric data. Ku`ulei Rodgers and 

colleagues from the University of Hawai`i Coral Reef Assessment and Monitoring Program (CRAMP) team collected the 

rapid assessment data referred to in this document. Will Smith 

and other CRAMP team members performed the third-party 

field-check observations and provided the accuracy assessment 

calculations. Melia Laber of the National Park Service provided the aerial photography in digital format. Sallie Beavers 

from Kaloko-Honoköhau NHP assisted with logistics while 

we were on island. This manuscript benefited from reviews 

by Mike Field and Guy Cochrane. A special mahalo goes to 

Captain Joe Reich, owner of the Alyce C on Moloka`i, whose 

exceptional navigation and local expertise was critical to the 

success of this project.

Table 5. Matrix showing accuracy assessment for the major biological cover classes.

Found to be in field

Total User’s

Coral Accuracy Coralline 

Algae

MacroalgaeTurf 

Algae Octocoral Emergent Vegetation Uncolonized

As

mapped

Coral 160 169 94.67%

Coralline Algae 0 15 0 0 0 0 1 16 93.75%

Macroalgae 0 0 0 0 0 0 3 3 0.00%

Turf Algae 0 0 0 0 0 0 0 0

Octocoral 0 0 1 0 3 0 1 5 60.00%

Emergent Vegetation 0 0 0 0 0 0 0 0

Uncolonized 6 0 0 0 0 0 42 48 87.50%

Total 166 16 1 0 4 0 54

Producer’s Accuracy 96.39% 93.75% 0.00% 75.00% 77.78% 241

Diagonal Sum = 220

Overall Accuracy = 91.29%

References

Coyne, M.S., Battista, T.A., Anderson, M., Waddell, J., 

Smith, W., Jokiel, P., Kendall, M.S., and Monaco, M.E., 

2003, Benthic habitats of the main Hawaiian Islands: 

NOAA Technical Memorandum NOS NCCOS CCMA 152 

[http://ccma.nos.noaa.gov/products/biogeography/hawaii_

cd/index.htm]. 

Grossman, E.E., Logan, J., Storlazzi, C.S., Paytan, A., and 

Street, J., 2006, Mapping groundwater discharge and nutrient flux across the fringing reefs of south Moloka`i and west 

Hawai`i, main Hawaiian Islands: Eos Transactions American Geophysical Union, v. 87, no. 36, Ocean Sci. Meet. 

Supplement (CD-ROM), abstract OS46N-13.

Kendall, M.S., Monaco, M.E., Buja, K.R., Christensen, J.D. 

Kruer, C.R., Finkbeiner, M., and Warner, R.A., 2001, Methods used to map the benthic habitats of Puerto Rico and 

the U.S. Virgin Islands: U.S. National Oceanic and Atmospheric Administration [http://ccma.nos.noaa.gov/products/

biogeography/benthic/index.htm].

Kendall, M.S., Buja, D.R., Christensen, J.D., Kruer, C.R., 

and Monaco, M.E., 2004, The seascape approach to coral 

ecosystem mapping; an integral component of understanding the habitat utilization patterns of reef fish: Bulletin of 

Marine Science, v. 75, no. 2, p. 225–237.

Lillesand, T.M., and Keifer, R.W., 1994, Remote sensing and 

image interpretation (3rd ed.): New York, John Wiley and 

Sons, 750 p.

Ma, Z., and Redmond, R.L., 1995, Tau coefficients for accuracy assessment of classification of remote sensing data: 

Photogrammetric Engineering and Remote Sensing, v. 61, 

p. 435–439.
16  Pu`uhonua O H–

onaunau National Historical Park, Hawai`i—Benthic Habitat Mapping

National Oceanic and Atmospheric Administration National 

Centers for Coastal Ocean Science, 2005, Shallow-water 

benthic habitats of American Samoa, Guam, and the Commonwealth of the Northern Mariana Islands: NOAA Technical Memorandum NOS NCCOS 8 [http://ccma.nos.noaa.

gov/products/biogeography/us_pac_terr/index.htm].

Richmond, B.M., #OCHRAN3!ANDGibbs, A.E., , 

Geologic resource evaluation of Pu`uhonua O Hönaunau National Historical Park; Part I, Geology and coastal 

landforms: U.S. Geological Survey /PEN
&ILE

Report 200-P.;HTTPPUBSUSGSGOVOF=

Rodgers, K.S., Jokiel, P.L., and Brown, E.K., 2004, Rapid 

assessment of Kaloko/Honoköhau and Pu`uhonua o Hönaunau, West Hawai`i: Hawai`i Coral Reef Assessment and 

Monitoring Program (CRAMP), Hawai`i Institute of Marine 

Biology, 56 p.

Rohman, S.O., and Monaco, M.E., 2005, Mapping southern 

Florida’s shallow-water coral ecosystems; an implementation plan: National Oceanic and Atmospheric Administration Technical Memorandum NOS NCCOS 19, 39 

p. [http://ccma.nos.noaa.gov/publications/biogeography/

FloridaTm19.pdf].
Appendix 17

Appendix 

Detailed Classification Scheme

The following describes the classification scheme used 

by the U.S. Geological Survey for benthic habitat mapping 

of National Parks on the Kona Coast of Hawai`i. Each of the 

habitats and zones is described in detail with some example 

photos. Many of the descriptions are from NOAA’s classification scheme for the main eight Hawaiian Islands (Coyne and 

others, 2003), and subsequent revision (National Oceanic and 

Atmospheric Administration National Centers for Coastal 

Ocean Science, 2005).

Habitats

Major Structure—Unconsolidated Sediment

Mud Fine sediment often associated with stream discharge 

and buildup of organic material in areas sheltered from highenergy waves and currents (for example, harbors, fishponds).

Major Structure—Reef and Hardbottom

Aggregate reef Formations with high relief and complexity, 

which form an extensive reef structure without sand channels 

(as found in spur-and-groove). Note that aggregate reef refers 

to the underlying hard structure and implies nothing about the 

nature of the biological cover, nor whether it is live or dead. 

Sand Coarse sediment typically found in areas exposed to 

currents or high wave energy (reef-derived) or on beaches 

(land-derived or reef-derived).

Spur-and-groove Elongate, alternating sand and coral formations that are oriented perpendicular to the shore or bank/shelf 

escarpment. The coral formations (spurs) of this feature typically have a high vertical relief relative to the pavement with 

the channels, and are separated from each other by 1–5 meters 

Example of muddy shallow area exposed at low tide. of sand or bare pavement (grooves).

(Kawela, Moloka`i) 

Example of uncolonized sand. (Kaloko-Hon–okohau, Hawai`i)

Example of aggregate reef with 90–100 percent coral. 

(Kawaihae Bay, Hawai`i)

Example of spur-and-groove reef system with 90–100 percent 

coral cover on the spurs. (Kawaihae Bay, Hawai`i)
18 Pu`uhonua O H–

onaunau National Historical Park, Hawai`i—Benthic Habitat Mapping

Individual patch reef Coral formations, larger than or equal 

to the MMU (100 m2 in this study), that are isolated from other 

coral reef formations by sand, seagrass, or other habitats and 

that have no organized structural axis relative to the contours 

of the shore or shelf edge. 

Aggregated patch reefs Clustered coral formations, smaller 

than the MMU (100 m2 in this study) or too close together to 

be mapped separately, that are isolated from other coral reef 

formations by sand, seagrass, or other habitats and that have 

no organized structural axis relative to the contours of the 

shore or shelf edge.

Volcanic pavement with sand channels Having volcanic substrate alternating with sand channels that are oriented perpendicular to the shore or bank/shelf escarpment. The sand channels 

have low vertical relief relative to spur-and-groove formations.

Volcanic pavement Volcanic substrate with less than 10 percent loose rocks or boulders scattered on the surface. May be 

smooth or irregular, depending on the original lava flow and 

subsequent erosion patterns.

Example of volcanic pavement with 50–<90 percent coral cover. 

(H–onaunau Bay)

Example of volcanic pavement with sand channels, with 90–100 

percent coral cover. (Kaloko-Honok–ohau, Hawai`i)

Example of aggregated patch reefs covered with 50–<90 percent 

coral. These patch reefs are smaller than the minimum mapping 

unit and so could not be called individual patch reefs. They 

would be digitized together, along with the others shown in the 

background, as aggregated patch reefs. (Moloka`i)

Volcanic pavement with 10– 50 percent rocks/boulders 

Volcanic substrate with 10–50 percent volcanic rocks and/or 

boulders scattered on the surface. The underlying substrate 

may be smooth or irregular, depending on the original lava 

flow and subsequent erosion patterns.

Example of volcanic pavement with 10–50 percent rocks/boulders, 

with 10–50 percent coral cover. (H–onaunau Bay, Hawai`i)
Appendix 19

Major Structure—Other 

Land Area shoreward of the mean high water line, or landward edge of emergent vegetation, when present.

Artificial Manmade habitats such as large piers, submerged 

parts of riprap jetties, and shoreline areas created from dredge 

spoil.

Artificial/historical Manmade features of historical significance, such as active and relict fishpond walls.

Zones

Land Area shoreward of the mean high water line, or landward edge of emergent vegetation, when present.

Shoreline/intertidal Area between the mean high water line 

(or landward edge of emergent vegetation) and lowest spring 

tide level. Typical habitats include mangrove and other emergent vegetation, sand, mud, and uncolonized rock.

Vertical wall Area with near-vertical slope along channels, 

from shelf to shelf escarpment, or between different innershelf platforms. This zone is typically narrow and may not be 

visible in remotely sensed imagery, but is included because 

it is recognized as a biologically important feature. Typical 

habitats include coral, algae, and uncolonized rock.

Lagoon The shallow area between the shoreline/intertidal 

zone and the back reef zone of a barrier reef system. If no 

reef crest is present, there is no lagoon zone. Typical habitats 

include individual patch reefs, sand, seagrass, algae, and pavement. (Not typically used for the Kona Coast.)

Back reef (with lagoon) Area between the seaward edge of a 

lagoon floor and the landward edge of a reef crest. This zone 

is only present when a reef crest and lagoon exist. Typical 

habitats include sand, coral rubble, seagrass, algae, and patch 

reefs. (Not typically used for the Kona Coast.)

Reef flat (without lagoon) Shallow, semiexposed area 

between the shoreline/intertidal zone and the reef crest of a 

fringing reef system. This zone is protected from the highenergy waves commonly experienced on the reef crest and fore 

reef. The reef flat is not present if there is a lagoon. Typical 

habitats include sand, rubble, pavement, algae, mud, and patch 

reefs.

Reef crest The flattened, emergent (especially during low 

tides) or nearly emergent segment of a reef, usually where the 

waves break. This zone lies between the back reef and fore 

reef zones of a barrier reef system, and between the reef flat 

and fore reef of a fringing system. Typical habitats include 

reef rubble, patch reefs, and aggregate reefs.

Volcanic pavement with >50 percent rocks/boulders Volcanic substrate with >50 percent volcanic rock and/or boulders 

on the surface. The underlying substrate may be smooth or 

irregular, depending on the original lava flow and subsequent 

erosion patterns.

Example of volcanic pavement with >50 percent rocks/boulders 

with <10 percent cover, therefore 90–100 percent uncolonized. 

(Kaloko-Honok–ohau, Hawai`i)

Reef rubble Dead, unstable coral rubble, often covered with 

coralline algae or filamentous or other macroalgae.

Example of reef rubble with <10 percent cover, therefore 90–100 

percent uncolonized. (Kawaihae Bay, Hawai`i)
20 Pu`uhonua O H–

onaunau National Historical Park, Hawai`i—Benthic Habitat Mapping

Fore reef Area from the seaward edge of the reef crest that 

slopes into deeper water to the landward edge of the bank/

shelf platform. Also defined as fore reef are features not 

forming an emergent reef crest but still having a seaward-facing slope that is significantly greater than the slope of the 

bank/shelf. Typical habitats include aggregate coral reef and 

spur-and-groove.

Bank/shelf A deep-water platform extending offshore 

from the seaward edge of the fore reef to the beginning of 

the escarpment where the insular shelf drops off into deep, 

oceanic water. If no reef crest is present, the bank/shelf is the 

flattened platform between the shoreline/intertidal zone and 

deeper ocean offshore. Typical habitats include sand, patch 

reefs, algae, colonized and uncolonized pavement with and 

without sand channels, and other coral habitats.

Bank/shelf escarpment The edge of the bank/shelf where 

depth increases rapidly into deep, oceanic water. This zone 

begins at approximately 20 to 30 meters depth, near the depth 

limit of features visible in aerial images. This zone captures 

the transition from the shelf to deep oceanic waters. Typical 

habitats include sand, aggregate reef, and spur-and-groove.

Channel Naturally occurring channels that often cut across 

several other zones. Typical habitats include sand, mud, and 

uncolonized pavement.

Dredged Area in which natural geomorphology is disrupted 

by excavation or dredging (for example, harbors and manmade 

channels). Typical habitats include rubble, sand, and mud.

Unknown Zone uninterpretable because of turbidity, cloud 

cover, water depth, or other interference.