National Park Service

South Florida/Caribbean I&M Network (SFCN)

Benthic Community Extent & Distribution

Reef Terrace Habitat in Dry Tortugas National Park
Reef Terrace Habitat in Dry Tortugas National Park.

Benthic Map Reports

For more information contact:
Michael Feeley, Ph D.

Importance/Issues

The extent, distribution, and composition of major benthic communities (e.g., hard bottom, soft-bottom, dense Thallasia sp. seagrass, sparse seagrass, etc.) across bays and marine areas influence the fish, invertebrate, and larger vertebrate communities (e.g., sea turtles, manatees) they support. Benthic communities can change with alterations in location, quantity and quality of freshwater and sediment inputs (e.g., CERP), nutrient levels, major storm events, and heavy visitor use (e.g., repeated boat groundings, scarring, and anchoring damage). Analysis of remotely-sensed data provides the spatial extent and composition of major benthic communities across relevant areas of marine parks allowing tracking of changes in large-scale patch size and shape at a broader scale than site-specific studies.

Approach

SFCN is working to gather and, where necessary, improve maps of benthic community extent and distribution in SFCN parks in order to provide an accurate baseline for monitoring design. Approach and funding source varies with each park. Maps will only be updated as additional funding becomes available.

Park-specific Benthic Mapping Projects

Dry Tortugas National Park

Dry Tortugas 2010 Benthic Habitat Map
Dry Tortugas 2010 Benthic Habitat Map.

In 2008 an initial benthic habitat map was completed by the contractor Avineon, Inc. The National Park Service South Florida / Caribbean Network conducted an accuracy assessment of the map and found the overall map classification accuracy to be acceptable (83.2%; lower 90% CL=79.8%). However, upon further inspection, the soft-bottom habitat classifications displayed a relatively high level of accuracy (89.4%; lower 90% CL=85.2%), while the hard-bottom habitats were below an acceptable level (75.2%; lower 90% CL=69.1%). With the acquisition of new higher resolution side scan sonar data and 2,054 field data points from multiple sources, the 2008 map was revised and improved by utilizing these new data sets to produce the 2010 Dry Tortugas benthic habitat map.

The 2010 Dry Tortugas benthic habitat map was developed using 13 mapping classes and 1,709 polygons totaling an area of 26,229 hectares. All "Unknown" areas (10,444 hectares) in the 2008 map were identified, the line work for the hard-bottom areas was fine-tuned, and a mapping layer was developed showing those areas which have a higher potential for fish and benthic biodiversity. In addition, a final bathymetry layer for the park was developed by merging the existing light detection and ranging (LiDAR) and newly acquired side scan sonar/bathymetry data. A subsequent accuracy assessment of the 2010 map found an overall raw accuracy of 89.7% (lower 90% CL=86.0%). The accuracy of hard bottom habitats improved to 88.0% (lower 90% CL=83.4%).

The current management plan for the Dry Tortugas National Park (DRTO) marine areas focuses much of its effort on the no-take Research Natural Area (RNA). The intensive amount of research effort placed on the RNA has also accomplished the research needed for the rest of DRTO because current research and monitoring efforts are split equally between areas of the DRTO that fall within and outside the RNA to make for a balanced comparative study design. In February of 2007, the National Park Service and Florida Fish and Wildlife Conservation Commission developed a science plan to assess conservation effectiveness for the RNA in conjunction with the rest of DRTO and two nearby existing no-take marine reserves.

The new benthic habitat map and corresponding products characterize what types of marine habitats are located in DRTO and provide the ability to track whether management interventions are effectively protecting the environment and associated resources.

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Last Updated: March 28, 2017 Contact Webmaster