Coastal Services Center

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Why Map Benthic Habitat?

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Knowledge of seafloor habitats is necessary for development and implementation of a wide variety of resource management policies. For example, in 1996, the Fishery Conservation and Management Act of 1976 (also known as the Magnuson-Stevens Act) was revised to include preservation of Essential Fish Habitat (EFH). EFH is defined as any habitat necessary for the complete life cycle of a commercially important fish. Benthic habitat mapping provides a means both to identify EFH and to characterize it in the context of the larger seafloor in order to determine the most effective means for preservation.

An aerial photograph of a section of Culebra Island, Puerto Rico (left) was used to develop a benthic habitat map (right). This example map shows a variety of different nearshore habitats, which are important for production and maintenance of healthy fisheries. Courtesy: NOAA Biogeography Program

Other important habitats, such as coral reefs, eelgrass beds, and shellfish beds, can be monitored over time using benthic mapping techniques. Such monitoring leads to more effective management and preservation.

• Mapping can be used to estimate the physical damage caused by trawl-fishing gear to seabed sediments and benthic animals.
• The locations of marine reserves can be planned based on detailed knowledge of critical habitats.
• Locations for aquaculture facilities can be planned through benthic mapping. For example, information about natural hard clam habitats can be used to determine suitability of other areas for hard clam aquaculture programs.

Benthic habitat mapping is also a useful tool for determining the effects of habitat change due to natural or human impacts. Many studies have looked at the impact of fishing gear on the benthos, in an effort to determine how much damage fishing does to the habitat and organisms. By mapping these habitats over time, recovery rates can be estimated. This is important for deciding whether or not, and for how long, areas should be closed to fishing to allow a full recovery.

Maintenance of shipping channels in estuaries also creates a need for benthic mapping. To keep these channels deep enough for commercial vessels, they must be routinely dredged to remove material (that is, sediment, debris, and organic matter) that has been washed from the land and accumulated on the bottom. During the process of dredging, this material is removed and must be deposited elsewhere. The health of the benthic habitat is of concern, so both the area being dredged and the area in which dredged material will be deposited must be well known. It is crucial to assess the impact such activities will have on the benthic habitat, and to monitor these habitats over time to verify that they recover sufficiently.

Want to learn more?

Several examples of how benthic mapping is used for coastal management are highlighted in the Applying Benthic Data section of this Web site. These include:

• Dredging and disposal of marine sediments
• Contaminants mapping
• Fisheries management

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