ECOSYSTEMS - HABITAT TYPES/COMPLEXES

Eelgrass - Zostera marina

Zostera marina is a species of nutrient poor shallow water tidal rivers, bays and ocean environments. Nutrient enrichment from atmospheric sources, groundwater, lawn and agricultural lands and sewage treatments plants contribute to the Zostera declines. Common mechanisms are shading effects that result from nitrogen enrichment including but not limited to increased phytoplankton production, epiphytic algae production and benthic algae. Nitrogen enrichment might also create stress that makes Zostera more susceptible to the eelgrass blight.

• Mapping Zostera beds - a common technique employed by states is to map the extent of Zostera beds by aerial photo intrepretation, boat/diver surveys, and towed video cameras. Sequential mapping and overlap analysis can be used to establish long-term trends. Zostera surveys include the following:
  • Long Island Sound (only eastern LIS where Zostera persists) is mapped on a 2-3 year cycle (spring time weather permitting) using aerial photography and aerial photointerpretation through the USFWS Southern New England/NY Bight program with base funding providing the EPA LISS. Photo years include 2002, 2006 and 2009 (to be available in 2010). The produce is georeferenced shapefiles. Shapefiles can be downloaded from CT DEP.
  • Rhode Island Sounds surveys include 1996 (Narrgansett Bay) and 1999-2000 are available as shapefiles from the Coastal Resources Management Council and an online eelgrass viewer.
  • Massachusetts maps are generally available for the periods of 1995 and 2001 and are available for viewing with the Interactive Eelgrass Viewer or download a shapefile at MassGIS
  • New Hampshire has a series of maps for Great Bay from 2004 to 2007 available as downloads from NH GRANIT.
  • Maine eelgrass mapping has been conducted at irregular intervals from the period of 1992 to 2005 and are available for viewing using the Eelgrass Map viewer and by download at Maine GIS.
  • Connecticut River Wetlands of International Importance includes the region from the mouth of the river upstream to Portland/Cromwell an includes a fresh and brackish water that supports extensive areas of fresh and brackish submerged aquatic vegetation including species such as Ruppia maritima, Vallisneria americana and a variety of Potamogeton species. SAV beds have only been mapped once in the period of 1995-1997(?).
• Long-term monitoring sites
  • Seagrass NET is a global seagrass monitoring network. Using permanent plots, a standard suite of parameters are measured at each location such as species composition via transect, cover, canopy height, density, reproduction and depth.
    • New Hampshire at Fishing Island and Great Bay
    • Massachusetts at Duck Island, Hog Island and Salem Sound
    • Rhode Island at Fort Getty and Prudence Island
    • New York at Fire Island National Seashore
  • Niantic Bay and Niantic River, East Lyme and Waterford, CT. Long-term (20+ years of surveys have been performed to assess the impacts of a thermal discharge from a nuclear power facility upon a variety of parameters including Zostera.
  • Great Bay, NH?
    

Benthic Habitat

• Northeastern Bentho-pelagic Observatary - A WHOI initiative to establish four sentinel monitoring sites in the northeast where benthic community structure, the coupling between the water column and benthic community, and system change over time scales of days to years will be quantified. Instruments to be towed from a commercial fishing vessel over defined tracks at least twice a year over a three year period to quantify benthic and plankton community structure. Additional detailed can be found in the proposal.
• National Undersea Research Center (NURC) for the North Atlantic and Great Lakes at the University of Connecticut has a mission to understand, sustain and conserve the resources of the oceans and Great Lakes by supporting underwater exploration, research and education. The interactive research map shows the numerous sites in the northeast where dives and surveys have occurred. A recent collaboration with Stellwagen Marine Sanctuary for a Marine Heritage and Monitoring Cruise produced video of a Cerianthid forest. New high definition video cameras are mounted on submersible to produce habitat fly in and serve to provide seafloor mapping ground-thruthing.

 

Tidal Wetlands

• Mapping of tidal wetlands is typically done using aerial photography to show the overall extent of tidal wetlands. Overlay analysis can be used to detect gross changes in wetalnds such as losses or gains. Georeferencing historic charts such as "topographic sheets" can used to quantify long-term trends.
• Trend Analysis
  • Western LIS submergence. Six embayments in CT were selected in western LIS where submergence (conversion from low marsh to intertidal flats) had been occurring for decades. Aerial photography acquired at five year intervals since 1974 were used to derive to classify wetland habitats using the National Wetlands Inventory classification. These data are being evaluated to determine how the rates of loss change across 5-year time intervals. As new photography is acquired, wetland loss trends can be reassessed.
    
    NY Department of Environmental Conservation used 1974 and 2000 (?) photographs to quantify acres of wetland converted from low marsh to intertidal flat.
• Plant community mapping. Plant community mapping is a time consuming technique that requires the development of a classification and then field delineation or the use of photointerpretation and field truthing to map communities. Future remapping can be used to detect community trends. Another approach is the use of Cowardin classification (e.g., community complexes). Wetland sites with community maps include:
  • Barn Island Wildlife Management Area, Stonington, CT (various years since 1947);
  • Great Meadows, Stratford, CT (1987)
  • Ragged Rock Creek, Old Saybrook, CT (2007?)
  • National Wetlands Inventory
    • NWI maps have been produced for each New England state at different times and scales.
    • The USFWS and NPS have plans to implement the application of the NWI classification in northeast Refuges and Parks to assess wetland response to accelerated sea level rise.
• Marsh Elevation Change - Sediment Elevation Tables (SET). Benchmarks are established in tidal marshes to allow for the measurement of long-term marsh elevation change. These measurements are used to assess marsh response to accelerated sea level rise from climate change. This technology is relatively new and scientists do not really know how marsh elevation changes in response to natural cycles like the lunar nodal cycle. Various projects and programs use SET's but a few programs have established or are establishing networks for climate change purposes. Some of the SET's in the northeast are shown here.
  • USGS has established an network of SET's on the eastern seaboard to evaluate the effects of sea level rise and nitrogen enrichment upon marsh elevation change. Northeast sites include Great Meadows in Stratford, CT and
  • The NPS has SET's installed in northeast parks including Fire Island National Seashore, Cape Cod National Seashore and Acadia National Park.
  • CT DEP has the SET supplies to create a network of sites on the north shore of Long Island Sound which will supplement the existing SET sites. An online database created by Connecticut College for the SET data is being moved to LISICOS.
  • NY DEC in partnership with NY USGS has established a series of SET sites on Long Island to monitor wetland response to sea level rise. Some of these sites include tide gauges, temperature and salinity.
  • NERRS SET's?
  • USFWS REFUGES?
  • Plum Island LTER
• Salt wedge changes and marsh response. USGS has forecast that as the snow pack in New England decreases, the spring freshet volume will be reduced and will arrive earlier on certain large New England Rivers. USGS has not completed an analysis for the Connecticut River, but in anticipation that a similar change will occur, it is expected that the salt wedge will move further upstream. This will be exacerbated by accelerated sea level. At risk are the fresh and brackish tidal wetlands, the best examples in the northeast and an underlying basis for the rivers' designation as a Wetland of International Importance under the Ramsar Convention. CT DEP funded a cooperative project between the University of Connecticut and CT USGS to establish long-term climate change monitoring of salinity patterns. Two installations were funded, one at Old Lyme (operational summer 2009) and Essex (to be operational in spring 2010). Essex currently represents the boundary between the oligohaline brackish Typha marshes and the freshwater tidal marshes. It is anticipated that these observations will be augmented with permanent vegetation transects to assess marsh response to changes in the salt wedge position and potential dampening of the spring freshet.
• Microrelief Plots. In 1973, Dr. William Niering and Dr. Scott Warren established 10 microrelief plots in tidal wetlands to create baseline data that would allow for the documentation of long-term changes in elevation and vegetation composition. Plots are 10 meters wide and length varies but typically extends from a creek to the uplands. A few of the eastern ones were resurveyed in 1988 and 1998. In 1998, new (1 or 2?) plots were established at Barn Island, Stonington, CT - a long-term research site. Using a 1 m2 grid, elevation and plant species are recorded at each grid intersection.
• Permanent Vegetation Transects -