Northwestern Hawaiian Islands Classification Scheme

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. | Description Source: NOS - Biogeography Program

Coarse sediment typically found in areas exposed to currents or wave energy. | Description Source: NOS - Biogeography Program

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. | Description Source: NOS - Biogeography Program

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. | Description Source: NOS - Biogeography Program

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. | Description Source: NOS - Biogeography Program

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. | Description Source: NOS - Biogeography Program

Rubble with 10-50 percent cover of macroalgae or turf algae. Turf algae is the most frequent cover type. | Description Source: NOS - Biogeography Program

Rubble with greater than 50% cover of macroalgae or turf algae. | Description Source: NOS - Biogeography Program

Sediment composed of approximately even amounts of sand and rubble that cannot be separately distinguished in the imagery for the given area. | Description Source: NOS - Biogeography Program

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. | Description Source: NOS - Biogeography Program

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. | Description Source: NOS - Biogeography Program

Discontinuous macroalgae and/or turf algae, covering 10-50 percent of the hardbottom substrate. | Description Source: NOS - Biogeography Program

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. | Description Source: NOS - Biogeography Program

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. | Description Source: NOS - Biogeography Program

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. | Description Source: NOS - Biogeography Program

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. | Description Source: NOS - Biogeography Program

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 greater than 10 percent colonization by live coral. | Description Source: NOS - Biogeography Program

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. | Description Source: NOS - Biogeography Program

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. | Description Source: NOS - Biogeography Program

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. | Description Source: NOS - Biogeography Program

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. | Description Source: NOS - Biogeography Program

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. | Description Source: NOS - Biogeography Program

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. Unlike 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. | Description Source: NOS - Biogeography Program

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. Unlike 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. | Description Source: NOS - Biogeography Program

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. Unlike 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. | Description Source: NOS - Biogeography Program

Shallow-water coral reef formations, with discontinuous macroalgae and/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. Unlike 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. | Description Source: NOS - Biogeography Program

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. Unlike 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. | Description Source: NOS - Biogeography Program

Clustered patch reefs that are individually too small (less than the MMU) or are too close together to map as individual patch reefs. | Description Source: NOS - Biogeography Program

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. | Description Source: NOS - Biogeography Program

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. | Description Source: NOS - Biogeography Program

Flat, low-relief, solid carbonate rock. | Description Source: NOS - Biogeography Program

Flat, low-relief, solid carbonate rock, with discontinuous macroalgae and/or turf algae, covering 10-50 percent of the hardbottom substrate. | Description Source: NOS - Biogeography Program

Flat, low-relief, solid carbonate rock, with discontinuous to continuous macroalgae and/or turf algae covering greater than 50 percent of the hardbottom substrate. | Description Source: NOS - Biogeography Program

Flat, low-relief, solid carbonate rock. Habitats within this category have greater than 10 percent colonization by live coral. | Description Source: NOS - Biogeography Program

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. | Description Source: NOS - Biogeography Program

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. | Description Source: NOS - Biogeography Program

Flat, low-relief, solid carbonate rocks. Discontinuous to continuous macroalgae and/or turf algae, covering greater than 50 percent of the hardbottom substrate. | Description Source: NOS - Biogeography Program

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. | Description Source: NOS - Biogeography Program

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. | Description Source: NOS - Biogeography Program

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. | Description Source: NOS - Biogeography Program

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. | Description Source: NOS - Biogeography Program

Substrate of exposed basalt rock, which frequently includes large boulders and blocks. This habitat is typically found in nearshore environments around some basalt islands. | Description Source: NOS - Biogeography Program

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. | Description Source: NOS - Biogeography Program

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. | Description Source: NOS - Biogeography Program

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. | Description Source: NOS - Biogeography Program

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. | Description Source: NOS - Biogeography Program

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". | Description Source: NOS - Biogeography Program

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. | Description Source: NOS - Biogeography Program

Area where excavation or dredging has occurred. | Description Source: NOS - Biogeography Program

Areas determined to be above the water line in the imagery at the time the imagery was acquired. | Description Source: NOS - Biogeography Program

Areas where the water or land surface in the imagery is obscured due to cloud cover. | Description Source: NOS - Biogeography Program

Areas where the water or land surface in the imagery is obscured due to shadow. | Description Source: NOS - Biogeography Program

Areas where the water or land surface in the imagery is obscured due to surf. | Description Source: NOS - Biogeography Program

Data dropouts in the imagery. | Description Source: NOS - Biogeography Program

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. | Description Source: NOS - Biogeography Program

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. | Description Source: NOS - Biogeography Program