The Data: Coastal Wetlands

Data Source: The coastal wetland data came from the U.S. Fish and Wildlife Service’s (FWS) National Wetlands Inventory (NWI; Dahl et al. 2000, p. 44). The data presented here include estuarine vegetated wetlands, which are approximately 87% of the total coastal wetlands included in the FWS report. Excluded types include estuarine non-vegetated and marine intertidal, neither of which fall into the category of “biologically structured habitat”— that is, they are not characterized by significant vegetation that is habitat for various animals and plants. Note that no estimate of “presettlement” coastal wetlands is included in this indicator. There are estimates of coastal wetlands prior to major development along the coastline that affected many wetlands. Gosselink and Baumann (1980) estimate that 10 million acres of coastal wetlands existed in 1923, which was prior to most of the coastal development.

Data Collection Methodology: The NWI produces periodic reports of changes in wetland area. The data, summarized in the aforementioned report, are derived from three separate analyses; one covering the 1950s to the 1970s; one covering the 1970s to 1980s, and one covering the 1980s to the 1990s. For this report, decadal estimates are presented as the midpoint of the decade. For example, “1980s” data are presented as “1985.” Note that more detailed data are available from the NWI maps and accompanying digital data but that acreage summaries are not compiled for national or regional reporting.

NWI counts all wetlands, regardless of land ownership, but recognizes only wetlands that are at least 3 acres. To ensure adequate coverage of coastal wetlands, supplemental sampling along the Atlantic and Gulf coastal fringes was added.

The patchy distribution of Pacific coast estuarine wetlands precluded gathering statistically valid data on this wetland type. Therefore, consistent with past studies, NWI did not sample Pacific coast estuarine wetlands such as those in San Francisco Bay, California; Coos Bay, Oregon; or Puget Sound, Washington.

A permanent study design is used, based initially on stratification of the 48 conterminous states by state boundaries and 35 physiographic subdivisions. Within these subdivisions are located 4375 randomly selected, 4-square-mile (2560 acres) sample plots. These plots were examined with the use of aerial imagery, ranging in scale and type; most were 1:40,000 scale, color infrared, from the National Aerial Photography Program.

Data Quality/Caveats: Field verifications addressing questions on image interpretation, land use coding, attribution of wetland gains or losses, and plot delineations were made. For example, for the analyses in the 1980s to 1990s, 21% of the sample plots were verified.

Data Access: The Status and Trend of Wetlands in the Conterminous United States 1986-1997 is available on the Web at http://wetlands.fws.gov/bha/SandT/SandTReport.html.

The Data Gap: Coral Reefs

According to the federal interagency Coral Reef Task Force (CRTF; http://coralreef.gov), accurate geo-referenced information on the exact location of specific natural resources and habitat types is essential for effective management of coral reefs. Comprehensive maps and habitat assessments form the foundation for a variety of reef conservation measures, including creating accurate baselines for long-term monitoring. However, according to the CRTF, most coral reefs in U.S. waters, and particularly those in the Pacific Ocean, have not been accurately mapped with modern techniques and at a scale relevant to emerging conservation issues.

In March 2000, the CRTF released a plan of action (http://coralreef.gov/CRTFAxnPlan9.PDF) committing the agencies to produce comprehensive digital maps of all coral reefs in the United States and trust territories within 5 to 7 years. During this period, the ongoing mapping of the Caribbean region will be completed, and new efforts will begin in the Pacific where critical data gaps presently exist. This interagency effort will produce maps at both low and high resolutions that address locally identified conservation and management needs.

The Data Gap: Shellfish Beds

The National Shellfish Register of Classified Growing Waters has been produced every 5 years since 1966; the most recent is the The State of the Nation’s Ecosystems: Technical Notes 218 1995 Register, released in 1997 (http://spo.nos.noaa.gov/projects/95register/). The Register is a cooperative effort among the nation’s shellfish-producing states, federal agencies such as the U.S. Food and Drug Administration and the National Oceanographic and Atmospheric Administration, and the Interstate Shellfish Sanitation Conference (ISSC).

The program’s focus is on the number and area of shellfish beds that are classified according to sanitary guidelines administered by the ISSC. States have been encouraged to monitor as broad a range of shellfish beds within their waters as possible, in order to protect public health. However, the resulting increase in area monitored confounds reporting on trends in overall shellfish bed area, making it inappropriate simply to report the acreage trends contained within the 1995 Register.

Note that shellfish beds that are no longer living (i.e., relict beds) continue to provide valuable habitat to marine organisms; over time, these beds will slowly disappear as the shells are dissolved.

The Data Gap: Submerged Aquatic Vegetation

While many programs monitor the extent of submerged aquatic vegetation (seagrasses, kelp, and other similar underwater plants), we are aware of no effort to compile and assess national trends. However, the United Nation’s Environment Program is actively gathering all available information on the worldwide distribution of seagrasses.

References

Dahl, T.E., et al. 2000. Status and trends of wetlands in the conterminous United States 1986-1997. Washington, DC: U.S. Department of the Interior, Fish and Wildlife Service. Gosselink, J.G., and R.H. Baumann. 1980. Wetland inventories: Wetland loss along the United States coast. Z. Geomorph. N.F. Suppl. Bd. 34:173–187.