Vital Signs: Seagrass Condition, Seagrass Distribution
Importance / Issues
Approximately one quarter of the NPS land area within the Northeast Coastal and Barrier Network is submerged. Diverse threats to NPS estuaries include natural disturbances (e.g., storms, sea-level rise), direct impacts of human activities (e.g., dredging, shellfishing, fishing, boating, dock construction), indirect effects of watershed development, and disasters. Jurisdictional issues surrounding submerged resources in migrating parks are sometimes unclear. Therefore, there is great potential for human disturbances to coastal watersheds, resulting in increased nutrient loading to park estuaries.
The causal relationships linking nutrient input, increased algal production, and declines in submerged aquatic vegetation (SAV) distribution and condition is well established. The primary mechanism for loss of SAV in response to increased nutrient load is attenuation of light by fast-growing phytoplankton, epiphytic microalgae, and free-floating macroalgae, resulting in reduced availability of light at macrophyte leaf surfaces. The trend in SAV distribution and condition over time offers an indicator of changes in nutrient load, while also providing information directly applicable to critical habitat protection efforts.
Preliminary Monitoring Objectives
Determine the distribution and abundance of submerged aquatic vegetation beds in selected areas in NCBN parks.
Determine long-term, inter-annual trends in seagrass condition (shoot density percent cover and biomass) in selected estuarine areas of NCBN parks.
Measure ancillary data, including Light Attenuation, Sediment Parameters, Temperature, and Salinity.
Parks to be Monitored
- Assateague NS
- Cape Cod NS
- Colonial NHP
- Fire Island NS
Data on submerged aquatic vegetation will be available for some of the parks to acquire from outside sources. Where not available, a methodological protocol is being created for the direct collection of these data. This protocol includes probability-based spatial sampling strategies, methods for incorporating non-Park Service data, and instruction on reporting and interpreting results. This protocol is also compatible with the NPS National Marine Water Quality Monitoring Effort and EPA National Coastal Assessment.
Contact InformationNPS Leads: Sara Stevens and Dennis Skidds
Principle Investigators: Hilary A. Neckles, Ph.D. and Blaine S. Kopp, Ph.D., USGS