Detailed, shallow-water coral reef ecosystem maps were generated by rule-based, semi-automated image analysis of high-resolution satellite imagery for nine locations in the Northwestern Hawaiian Islands. This project is a cooperative effort between the National Oceanic and Atmospheric Administration, State of Hawaii Department of Land and Natural Resources, and the U.S. Fish and Wildlife Service to produce benthic habitat maps and georeferenced imagery for the Northwestern Hawaiian Islands. This project was conducted in support of the U.S. Coral Reef Task Force.
The National Ocean Service is conducting research to digitally map biotic resources and coordinate a long-term monitoring program that can detect and predict change in U.S. coral reefs, and their associated habitats and biological communities. This project was conducted in support of the U.S. Coral Reef Task Force (http://coralreef.gov).
ground condition
These maps are NOT to be used for navigation. These detailed habitat maps of the shallow-water benthic habitats of the Northwestern Hawaiian Islands have been reviewed by numerous decision makers and scientists familiar with the Northwestern Hawaiian Islands region. Although they represent the best available characterizations of the shallow-water coral reef ecosystems of this region the maps should be considered DRAFT versions.
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NOAA, University of Hawaii, U.S. Fish and Wildlife Service
The accuracy assessment was performed on the aggregated cover benthic habitat maps only. This was due to the relatively few site-specific benthic characterization data available for the Northwestern Hawaiian Islands. A statistic based accuracy assessment was performed using a subset of the 1,130 site-specific benthic characterization data (376 points were used in the accuracy assessment) available for the NWHI. The overall accuracy of the aggregated cover maps was 72 percent (Kappa Statistic 0.59, Tau Coefficient 0.62), and ranged from 94 percent accuracy for unconsolidated sediment with little or no algae or seagrass to 9% for unconsolidated sediment with seagrass present.
Multispectral satellite imagery was positioned using National Geodetic Survey ground control data for Kure Atoll, Midway Atoll, Pearl and Hermes Atoll, Lisianski Island, Laysan Island, French Frigate Shoals, and Nihoa Island. Satellite imagery of Necker Island was positioned using satellite ephemeris data. Satellite imagery of Maro Reef was positioned using a combination of satellite ephemeris data and supplemental bathymetry transect data. Once maps were positioned, validation was performed by comparison to repositioned vector shoreline data depicted on recently-revised NOS nautical charts. The draft classified benthic habitat maps were reviewed by scientists in Hawaii with first-hand local knowledge of the Northwestern Hawaiian Islands. Comments were received and incorporated into draft maps. Draft maps also underwent a statistics-based accuracy assessment.
High-resolution satellite imagery was analyzed using rule-based, semi-automated, digital image analysis techniques to produce benthic habitat maps of the Northwestern Hawaiian Island. In total, 1,130 site specific examples of the spectral and spatial characteristics of differing habitats were available and incorporated into the analysis process for the NWHI. The minimum mapping unit (MMU) for identifying habitats or features was 100 sq. m. Generally, features to a depth of approximately 30 m can be analyzed from the satellite imagery. Due to the depth of water surrounding Gardner Pinnacles, very little characterization of the benthic habitats of Gardner Pinnacles was possible. No satellite imagery was available for Gambia shoals.
Spatial data meets or exceeds national map accuracy standards for fixed features. Kure Atoll, Midway Atoll, Pearl and Hermes Atoll, Lisianski Island, Laysan Island, French Frigate Shoals, and Nihoa Island are positioned to within five (5) meters at sea level. Necker Island is positioned to within 15 meters at sea level. Maro Reef is positioned to within eight (8) meters at sea level.
none reported
high resolution satellite imagery was analyzed to produce benthic habitat maps of the Northwestern Hawaiian Island
High resolution satellite imagery was analyzed using rule-based, semi-automated, digital image analysis techniques to produce benthic habitat maps of the Northwestern Hawaiian Island. Following careful evaluation of the digital satellite imagery, selected sites were visited in the field for typological validation. This validation included: (1) areas in the satellite imagery with confusing or difficult to interpret spectral signatures, (2) transects across many representative habitat types occurring in different depths and water conditions, (3) a survey of the Zones, and (4) confirmation of preliminary habitat delineations after a first draft habitat map was produced. Navigating to field sites was accomplished in a variety of ways including uploading position coordinates from the mosaic into an onboard GPS and navigating to those waypoints, using an onboard PC connected to GPS allowing navigation using digital nautical charts or the mosaic, and visual navigation using landmarks visible in the satellite imagery. On most occasions, field activities were conducted with the guidance of local experts. Satellite imagery was used in the field to facilitate comparison of signatures in the imagery to actual habitats at each site. Individual sites were visually evaluated by snorkeling and free diving or directly from the boat in shallow, clear water. Habitat transitions were evaluated by swimming transects across habitat types to further guide placement of habitat boundaries. Habitat type(s), zone, approximate depth, position (GPS), image number, and other descriptive information were recorded at each site. Field data for each site were then compiled into a text table with GPS position fields to allow overlay of the field information on the mosaic and habitat maps. Where depth and water clarity permitted, the satellite images were used to navigate across multiple bottom features allowing continuous confirmation of habitat types and transitions between each site.
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Mobile substrate that varies in coarseness (from mud to sand to rubble), and which is characterized by some degree of instability in response to water motions.
NOS - Biogeography Program
Coarse sediment typically found in areas exposed to currents or wave energy.
An area with 10-100 percent coverage of any combination of numerous species of red, green or brown macroalgae. Typically occurs at the base of patch and linear reef structures and can be a transient feature.
Discontinuous macroalgae (10-50 percent cover), with breaks in coverage that are too diffuse or irregular, or result in isolated patches of macroalgae that are too small to be mapped individually as dense beds.
Macroalgae covering 50-100 percent of the sand substrate. May include blowouts (no coverage) of less than 10 percent of the total area that are too small to be mapped independently.
Dead, unstable coral rubble that appears predominantly pebble- and cobble-sized. This habitat often occurs landward of well-developed reef crest formations or in the back reef, as well as at the base of patch reef and linear reef formations.
Rubble with 10-50 percent cover of macroalgae or turf algae. Turf algae is the most frequent cover type.
Rubble with greater than 50% cover of macroalgae or turf algae.
Sediment composed of approximately even amounts of sand and rubble that cannot be separately distinguished in the imagery for the given area.
Narrow, linear sand feature that alternates with coral formations in spur and groove habitat, and which oriented perpendicular to the shore or bank/shelf escarpment. Groove is delineated as an individual category when the channel is clearly larger than the MMU.
Hardened substrate of unspecified relief formed by the deposition of calcium carbonate by reef building corals and other organisms (relict or ongoing) or existing as exposed bedrock or volcanic rock. Habitats within this category typically have some colonization by live coral.
Discontinuous macroalgae and/or turf algae, covering 10-50 percent of the hardbottom substrate.
Substrates formed by the deposition of calcium carbonate by reef-building corals and other organisms. Habitats within this category have greater than 10 percent colonization by live coral.
Hard substrate composed of relict deposits of calcium carbonate or exposed volcanic rock. Habitats within this category have 10 percent or less coverage of hard coral or crustose coralline algae, but total coverage from both cover types may exceed 10 percent.
An area with 10 percent or greater coverage of any combination of numerous species of encrusting or coralline algae. This habitat is typically found on reef crest and in shallow back reef and fore reef areas.
Linear coral formations that often are oriented parallel to shore or the shelf edge, but which are also found within NWHI atolls, without a particular axis relative to the shore/shelf edge. This category included habitat structures that are commonly referred to as fore reef, fringing reef, and shelf edge reef.
Linear coral formations that often are oriented parallel to shore or the shelf edge, but which are also found with the NWHI atolls, without a particular axis relative to the shore/shelf edge. This category includes habitat structures that are commonly referred to as fore reef, fringing reef, and shelf edge reef. Habitats within this category have greaten than 10 percent colonization by live coral.
Linear coral formations that often are oriented parallel to shore or the shelf edge, but which are also found with the NWHI atolls, without a particular axis relative to the shore/shelf edge. This category includes habitat structures that are commonly referred to as fore reef, fringing reef, and shelf edge reef. Habitats within this category have 10 percent or less coverage of hard coral or crustose coralline algae, but total coverage from both types may exceed 10 percent.
Linear coral formations that often are oriented parallel to shore or the shelf edge, but which are also found with the NWHI atolls, without a particular axis relative to the shore/shelf edge, with discontinuous macroalgae and/or turf alga, covering 10-50 percent of the hardbottom substrate. Habitats within this category have 10 percent or less coverage of hard coral or crustose coralline algae, but total coverage from both types may exceed 10 percent.
Linear coral formations that often are oriented parallel to shore or the shelf edge, but which are also found with the NWHI atolls, without a particular axis relative to the shore/shelf edge, having an area with 10 percent or greater coverage of any combination of numerous species of encrusting or coralline algae.
Coral formations that are composed of relatively monotypic coral colonies, typically isolated from other shallow-water coral reef formations by unconsolidated sediment, where the hardened substrate is larger than the MMU. This habitat can include large individual coral heads and clusters of coral heads that are too small or too close together to be mapped separately. Habitats within this category have greater than 10 percent colonization by live coral.
Habitat having alternating sand and coral formations that are oriented perpendicular to the shore or bank/shelf escarpment. The coral formations (spurs) of this feature typically have a high vertical relief relative to pavement with sand channels and are separated from each other by 1-5 m of sand or bare hard bottom (grooves). The height and width of the spurs and grooves may vary considerably. This habitat type typically occurs in the fore reef or bank/shelf escarpment region and is frequently found seaward of breaks in the barrier reef.
Shallow-water coral reef formations that are isolated from other shallow-water coral reef formations by unconsolidated sediments and that have no organized structural axis relative to the contours of the shore or shelf edge. Unlink aggregated coral heads, patch reefs typically consist of a diverse assemblage of coral and algal species. Distinctive single patch reefs are larger than or equal to 100 sq. m.
Shallow-water coral reef formations that are isolated from other shallow-water coral reef formations by unconsolidated sediments and that have no organized structural axis relative to the contours of the shore or shelf edge. Unlink aggregated coral heads, patch reefs typically consist of a diverse assemblage of coral and algal species. Distinctive single patch reefs are larger than or equal to 100 sq. m. Habitats within this category have greater than 10 percent colonization by live coral.
Shallow-water coral reef formations that are isolated from other shallow-water coral reef formations by unconsolidated sediments and that have no organized structural axis relative to the contours of the shore or shelf edge. Unlink aggregated coral heads, patch reefs typically consist of a diverse assemblage of coral and algal species. Distinctive single patch reefs are larger than or equal to 100 sq. m. Habitats within this category have 10 percent or less coverage of hard coral or crustose coralline algae, but total coverage from both cover types may exceed 10 percent.
Shallow-water coral reef formations, with discontinuous macroalgae an/or turf algae covering 10-50 percent of the hardbottom substrate, that are isolated from other shallow-water coral reef formations by unconsolidated sediments and that have no organized structural axis relative to the contours of the shore or shelf edge. Unlink aggregated coral heads, patch reefs typically consist of a diverse assemblage of coral and algal species. Distinctive single patch reefs are larger than or equal to 100 sq. m. Habitats within this category have 10 percent or less coverage of hard coral or crustose coralline algae, but total coverage from both cover types may exceed 10 percent.
Shallow-water coral reef formations, having an area with 10 percent or greater coverage of any combination of numerous species of encrusting or coralline algae, that are isolated from other shallow-water coral reef formations by unconsolidated sediments and that have no organized structural axis relative to the contours of the shore or shelf edge. Unlink aggregated coral heads, patch reefs typically consist of a diverse assemblage of coral and algal species. Distinctive single patch reefs are larger than or equal to 100 sq. m.
Clustered patch reefs that are individually too small (less than the MMU) or are too close together to map as individual patch reefs.
Clustered patch reefs that are individually too small or are too close together to map as individual patch reefs. Habitats within this category have greater than 10 percent colonization by live coral.
Sand or rubble substrate with scattered rocks, or small, isolated coral-heads that are too small to be delineated individually (i.e., too small to be identified as individual patch reef or aggregated coral heads). Habitats within this category have greater than 10 percent colonization by live coral.
Flat, low-relief, solid carbonate rock.
Flat, low-relied, solid carbonate rock, with discontinuous macroalgae and/or turf algae, covering 10-50 percent of the hardbottom substrate.
Flat, low-relied, solid carbonate rock, with discontinuous to continuous macroalgae and/or turf algae covering greater than 50 percent of the hardbottom substrate.
Flat, low-relief, solid carbonate rock. Habitats within this category have greater than 10 percent colonization by live coral.
Flat, low-relief, solid carbonate rock, with discontinuous to continuous macroalgae and/or turf algae covering greater than 50 percent of the hardbottom substrate. Habitats within this category have greater than 10 percent colonization by live coral.
Flat, low-relief, solid carbonate rock, with 10 percent or less coverage or hard coral or crustose coralline algae, but total coverage from both types may exceed 10 percent.
Flat, low-relief, solid carbonate rocks. Discontinuous to continuous macroalgae and/or turf algae, covering greater than 50 percent of the hardbottom substrate.
Flat, low-relief, solid carbonate rocks, with 10 percent of greater coverage of any combination of numerous species of encrusting or coralline algae. This habitat is typically found on reef crest and in shallow back reef and fore reef areas.
Habitat with alternating sand and pavement substrates that are oriented perpendicular to the shore, fringing reef or bank shelf escarpment. The sand channels of this feature have low vertical relief relative to spur and groove formations. This habitat type occurs in areas exposed to moderate wave surge such as the bank/shelf zone or areas just landward of breaks in the barrier reef.
Habitat with alternating sand and pavement substrates that are oriented perpendicular to the shore, fringing reef or bank/shelf escarpment. The sand channels of this feature have low vertical relief relative to spur and groove formations. This habitat type occurs in area exposed to moderate wave surge such as the bank/shelf zone or areas just landward of breaks in the barrier reef. Habitats within this category have greater than 10 percent colonization by live coral.
Habitat with alternating sand and pavement substrates that are oriented perpendicular to the shore, fringing reef or bank/shelf escarpment. The sand channels of this feature have low vertical relied relative to spur and groove formations. This habitat type occurs in areas exposed to moderate wave surge such as the bank/shelf zone or areas just landward of breaks in the barrier reef. Habitats within this category have 10 percent of less coverage of hard coral or crustose coralline algae, but total coverage from both cover types may exceed 10 percent.
Substrate of exposed basalt rock, which frequently includes large boulders and blocks. This habitat is typically found in nearshore environments around some basalt islands.
Substrate of exposed basalt rock, which frequently includes large boulders and blocks. Discontinuous to continuous macroalgae and/or turf algae, covering greater than 50 percent of the hardbottom substrate.
Substrate of exposed basalt rock, which frequently includes large boulders and blocks. Habitats within this category have greater than 10 percent colonization by live coral.
Substrate of exposed basalt rock, which frequently includes large boulders and blocks. Habitats within this category have 10 percent or less coverage of hard coral or crustose coralline algae, but total coverage from both cover types may exceed 10 percent.
Describes several types of features found in the imagery that are not representative of shallow-water coral reef ecosystem. This specific category also is used to identify the saline lake found on Laysan Island.
Areas where the bottom cannot be detected (identified) in the imagery. In most cases, this occurs in water more than 30 m deep. However, turbidity in the water column can obscure the bottom in water as little as 5 m deep. Areas affected by turbidity and where field based supplemental information was lacking were labeled "unclassified".
The flattened, emergent or nearly emergent segment of a reef. This feature typically is found along barrier reef lines in NWHI and is frequently covered with dense macroalgae. Breaking waves are typically found at or just seaward of the reef crest and are delineated as surf if present in the imagery.
Area where excavation or dredging has occurred.
Areas determined to be above the water line in the imagery at the time the imagery was acquired.
Areas where the water or land surface in the imagery is obscured due to cloud cover.
Areas where the water or land surface in the imagery is obscured due to shadow.
Areas where the water or land surface in the imagery is obscured due to surf.
Data dropouts in the imagery.
Areas where the bottom type is unclassified because of turbidity in the water, surface glint, or other types of interference. This category also includes areas where the seabed cannot be classified due to a lack of supplemental field-based information, or for other reasons.
Refers to areas within the geographic bounds of the habitat map that lie outside the bounds of the acquired imagery. This is not a habitat category in the classification scheme.
Benthic features were assigned one of thirty habitat types ranging from sand to coral. A complete description of these classification categories can be found in the NWHI_class_scheme PDF file (http://ccmaserver.nos.noaa.gov/rsd/products/pdf/NWHI_class_scheme.pdf).
DETAILED HABITAT TYPE = Habitat_name, Habitat_classification_code, Numeric_value, Red_color_value, Green_color_value, Blue_color_value Habitat_name: The name of the benthic habitat identified and depicted. Habitat_classification_code: A hierarchical, 4-digit code assigned to each habitat type. Numeric_value: A two- or three-digit numeric value assigned to each habitat type. Red_color_value: A numeric value ranging from 0-255 assigned to the red channel of the RGB color palette. Green_color_value: A numeric value ranging from 0-255 assigned to the green channel of the RGB color palette. Blue_color_value: A numeric value ranging from 0-255 assigned to the blue channel of the RGB color palette
not to be used for navigation NOAA makes no warranty regarding these data, expressed or implied, nor does the fact of distribution constitute such a warranty. NOAA and NODC cannot assume liability for any damages caused by any errors or omissions in these data, nor as a result of the failure of these data to function on a particular system.The National Oceanic and Atmospheric Administration (NOAA) National Centers for Coastal Ocean Science (NCCOS) produced this data CD-ROM. NCCOS Biogeography Program does not guarantee the accuracy of the geographic features or attributes