Coastal Services Center

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Managing Coastal Estuaries

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The Goal:

Develop a long-range plan for coastal estuary management in a highly populated region.

The Issue:

How can organizations and agencies lessen the environmental impacts of future development?

The Answer:

Integrate satellite imagery and additional data sets to derive a base map depicting habitat loss and long-term change trends in a watershed.

The Example:
Barnegat Bay, New Jersey, Data Synthesis Project: Habitat Loss and Alteration

During the last 50 years, development has exploded along Barnegat Bay, a shallow, lagoon-type estuary located on the coast of central New Jersey. The bay and its 42 miles of shoreline offer many recreational activities such as boating, fishing, and swimming. In addition, the estuary is ecologically important as a breeding ground for oysters, clams, blue crabs, and many other commercially important fish. Protecting and managing the habitats of Barnegat Bay benefits the citizens of New Jersey not only by reducing damage to natural ecological systems that provide homes for a myriad of terrestrial and aquatic species, but also by preserving open space and multiuse recreational areas in a region characterized by dense residential and commercial development.

In 1995, after Barnegat Bay became part of the Environmental Protection Agency's National Estuary Program, work started on a long-range Comprehensive Conservation and Management Plan (CCMP) to minimize the harmful impacts of future development. As a part of this effort, the Rutgers University Center for Remote Sensing and Spatial Analysis (CRSSA) generated the Barnegat Bay Data Synthesis Project: Habitat Loss and Alteration. This comprehensive plan incorporated historical data, National Wetland Inventory data, benthic maps, satellite-derived digital land use/land cover data, and aerial photography to assess long-term changes to habitat.

Using Land Cover Data:

The base map for the data synthesis project's comprehensive mapping is land use/land cover data, produced by the Rutgers University Center for Remote Sensing and Spatial Analysis (CRSSA). Satellite-derived land cover data were developed from Landsat Thematic Mapper 1994/95 imagery using the NOAA C-CAP protocol (Dobson and others 1995). The initial land cover data set was augmented and adapted specifically for the Barnegat Bay Estuary Program. The Barnegat Bay data set incorporated 38 different land covers. This land use/land cover base was combined with U.S. Fish and Wildlife Service National Wetland Inventory maps, submerged aquatic vegetation (SAV) maps, and bathymetry derived from the NOAA nautical chart of Barnegat Bay to produce a seamless habitat map, as seen below, for the entire Barnegat Bay ecosystem. The resulting comprehensive synthesis map combined upland, wetland, and the benthic habitats of the Barnegat Bay watershed.

Landsat Multispectral Scanner (MSS) data from 1972 and Landsat Thematic Mapper data from 1984 were also mapped by CRSSA and used to establish change analysis trends to assist in measuring development processes and habitat loss within the Barnegat Bay watershed. The following example illustrates a generalized version of the methodology used to prioritize habitat crucial to open space and resource conservation.

Identifying Open Space for Habitat Conservation:

To identify areas for conservation within the Barnegat Bay watershed, the following data layers were overlaid and examined against the comprehensive synthesis map:

• Paved roads and existing developments serve as barriers to wildlife movement and facilitate the disturbance of natural environments; roads and developments were used to delineate individual patches of contiguous forest and fragmented forest areas.
• A 90-meter (270-foot) buffer from each stream bank was generated for all mapped streams. These riparian zones act as important corridors for wildlife and fish movement and dispersal, and link interior habitats to the coastal bay.
• A 150-meter (300-foot) buffer around the bay and salt marsh areas was used to examine the quantity of human development and impervious surfaces that border these critical habitat areas and aggravate runoff, sedimentation, and nonpoint source pollution.
• Extent of coastal marsh loss.
• Extent of submerged aquatic vegetation loss.

The comprehensive synthesis map for the the Barnegat Bay watershed and estuary. This graphic was provided by the Center for Remote Sensing and Spatial Analysis (CRSSA), Rutgers University.

CRSSA overlaid digital maps of important wildlife habitat and public conservation lands to generate a "gap" analysis. This analysis helps to identify existing areas of high habitat value that remain unprotected throughout the Barnegat Bay watershed.

Applying Land Cover Data:

With this gap analysis data, managers can grasp the extent of forest loss and fragmentation, as well as shoreline development. They can examine the current status of salt marshes and submerged aquatic vegetation and work to pinpoint gaps in conservation protection and policies.

The Trust for Public Land–a nongovernmental, nonprofit organization–used the maps to identify 100 critical sites in the Barnegat Bay watershed in need of protection. The group wanted to target land that would preserve water quality and wildlife habitat that was also adjacent to public land. Among the property acquired with the help of these data sets was a 342-acre parcel near New Jersey's Turkey Swamp Wildlife Management Area. This land will now preserve the headwaters of two major streams, protecting both surface water and groundwater quality and also helping to safeguard Barnegat Bay.

The Result:

Without satellite imagery, it would be nearly impossible to map the habitats of the Barnegat Bay watershed and difficult to protect the most vulnerable areas. By using these maps, state, county, and city planners, as well as nongovernmental organizations, can prioritize open space acquisitions and target areas needing special attention to maintain the integrity of the watershed.

To learn more about the Barnegat Bay watershed project, visit www.crssa.rutgers.edu/projects/runj/bbay.html, or see the recently published article in the Journal of Coastal Research, Special Issue #32, 2001, "Habitat Loss and Alteration in the Barnegat Bay Region" (Lathrop and Bognar 2001).

Works Cited:

Dobson and others, 1995. NOAA Coastal Change Analysis Program (C-CAP): Guidance for Regional Implementation. NOAA Technical Report NMFS 123. US Department of Commerce.

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