Objectives
1. Survey the habitat characteristics in 16 embayments of Long Island Sound.
2. Utilize standard indicators of estuarine water quality and eutrophication status (EPA, NOAA) to assess the relative "health" of these estuaries, comparing within Long Island Sound and to estuaries throughout the nation.
3. Assess these sites for their potential to support Zostera marina L. (eelgrass).
4. Identify the links between stresses to the embayments (nitrogen load, temperature), contributing factors (freshwater flushing time, size), and estuarine response (indices from #2, habitat characteristics).
5. Compare the habitat characteristics to historic data, where available. This includes evaluating changes in temperature and pH as possible indicators of climate change effects.
6. Develop a baseline set of data for future researchers working in Long Island Sound.
7. Present results to the scientific community, Long Island Sound managers, and stakeholders.
8. Introduce 6 undergraduate students (3 / y) to ecological field research, lab techniques, and data analysis for use in informing management and scientists on ecosystem status of small embayments.
Methods
1. Sample 16 embayments for core ecological indicators: water column profiles of O2, salinity, temperature, pH, light; nutrients; chlorophyll a; total suspended solids; sediment organic matter; macrophyte biomass and CHN; characterize the bottom habitat.
2. Deploy temperature loggers to get an annual record of temperature.
3. Gather previously collected habitat characteristic data for the sites.
4. Develop nitrogen load estimates for sites using a pre-existing spreadsheet based model.
5. Gather estimates of freshwater flushing times.
6. Apply water quality indices developed for other coastal assessment programs to these sites.
7. Analyze the relationships between N load, freshwater flushing time, and estuarine response (from #1 and #6).
8. Evaluate these sites for the potential to support eelgrass, using a GIS-based model developed as part of a separate project.
Rationale
For the majority of the more than 60 embayments of LIS, very little is known about their current eutrophic condition, dominant habitat type, potential to support submerged aquatic vegetation (SAV), or changes in community structure due to climate change effects. Small coastal embayments are the receiving waters for much of the nonpoint source nitrogen (N) being delivered into LIS. This nitrogen input has been identified as a major contributing factor to eutrophication and the loss of SAV in estuaries. By sampling in many sites across a range of nitrogen loads, the relationship between stressors (N, temperature, flushing time) and estuarine response (hypoxia, macroalgae blooms, loss of SAV) can be investigated. This data set can also be used to examine sites for the potential to support SAV and serve as a baseline for future work related to eutrophication issues and climate change effects.
Summary or Results
While nitrogen loading and eutrophication and resulting negative impacts on estuarine life have been extensively studied in Long Island Sound, little is known about the impacts on more than 60 small embayments that surround Long Island Sound. A collaborative NY/CT Sea Grant research project was conducted by Jamie Vaudrey and Charles Yarish at the University of Connecticut to survey habitat characteristics of 8 representative embayments in Connecticut and New York, examining estuarine status and the susceptibility of these embayments to hypoxia. The research team measured nitrogen loading based on land use for each embayment, restrictions to water flow within the embayments, and temperature. Results of the project showed that the degree of hypoxia in an embayment depended upon the interaction of the amount of nitrogen loading to the embayment the degree water flow to the sound was restricted and the temperatures experienced by the embayment.