A Connecticut Department of Energy & Environmental Protection and University of Connecticut Partnership
Long Island Sound Sentinel Monitoring for Climate Change Program

Matrix Development with Sentinels and Sentinel Indices

Given the two different approaches used by the CT and NY state-level work groups, it was necessary to reconcile the approaches and the information generated by each work group, as well as the documents generated by the EPA contractor ICF International. A table format was used to generate a preliminary matrix of LIS climate change impacts and indicators. Numerous discussions were held to clarify terms and definitions, as well as how best to organize the information (see Appendices E and F for discussions of the issues and concerns expressed by work group participants). The final matrix document (for the purposes of this strategic plan) features four tables:

  1. Water Quality/Quantity,
  2. Pelagic/Benthic Systems and Associated Species,
  3. Fisheries of Long Island Sound and Associated River Systems, and
  4. Coastal Habitats of Long Island Sound and Associated Species/Systems.

Each table includes a list of sentinels, and for each sentinel there are the following categories: monitoring question(s), ecological drivers of climate related change to the sentinel, responses of the sentinel to climate related factors, sentinel indice(s) (i.e. how is the sentinel measured or quantified), and what data have been collected to date. In addition, the following question is asked for each sentinel: Can climate change effects be distinguished from other stressors? The answer to this question may change as our knowledge grows. In addition, we anticipate that other sentinels will be added to the document in the future. This matrix of four tables (Appendix H) with sentinels and sentinel indices was then used to determine priorities for pilot monitoring (Section VII) along with an agreed-upon list of core parameters (Section V). Each of the four table categories is briefly described below:

A. Water Quality/Quantity

The physical and chemical characteristics of water that impact the biological abundance and diversity of plants and animals of LIS are important indicators in tracking impacts to cold water and warm water species as well as the areal extent of habitat favorable to those species. The problem of summertime low dissolved oxygen (hypoxia) in the western and central Sound is strongly influenced by density stratification separating surface and bottom water. Water column stratification is driven by temperature and salinity differences in water masses. As sea level rises and precipitation is predicted to increase in the region, it is expected that brackish tidal areas will shift, an overall lowering of salinity may occur, as well as warming of cold water habitats. Water quality monitoring funded by the LISS at open water sites in the Sound has provided a rich data set of parameters for water temperature, salinity, dissolved oxygen, and turbidity spanning 25 years and is a great resource to the region. With the increased awareness of ocean acidification impacts due to climate change, CTDEP also began monitoring pH in 2010.

Increased ocean acidity could have an adverse impact on the region’s shellfish industry if this process impinges calcification at various stages in shellfish growth and development.

The major focus of monitoring by the Long Island Sound Study has been on open waters, but a number of citizens volunteer monitoring groups in New York and Connecticut have accumulated a good data set of embayment parameters that could serve as a base to determine trends as part of a sentinel monitoring for climate change program.

B. Pelagic and Benthic Systems and Associated Species

The distribution and abundance of invasive species has been projected to increase as changes in temperature, salinity and pH regimes may increase the ability of invasive species from a wide range of plant and animal groups to compete with native species.

Within benthic communities, infaunal and epifaunal invertebrates have been predicted to migrate with changes in water temperature and salinity. However, it was noted by the technical work groups that these phenomena are difficult to monitor and that direct linkages to climate change may also be difficult to establish due to existing anthropogenic stressors in LIS. Both phytoplankton and zooplankton community composition may change with increasing water temperatures and new species may be introduced to the Sound. The earlier occurrence of spring phytoplankton blooms has been observed in other locations around the world and changes to the timing and extent of phytoplankton blooms may occur in LIS as well. Shifts from crustacean zooplankton (e.g., copepods) to gelatinous zooplankton (e.g., jellyfish) may also be associated with increased temperature and ocean acidity. Finally, changes in the finfish community are already being observed within survey catch data, with increasing water temperatures linked to a movement of species northward and warm-adapted species replacing coldadapted species in Long Island Sound.

C. Fisheries of Long Island Sound and Associated River Systems

Temperature is only one of a complex group of variables that individually or collectively drive ecological changes in LIS. Subsequently, it is difficult to definitively attribute or project changes in crustaceans, mollusks, and finfish populations without considering other environmental influences. The net effect of increased temperature on fish (crustaceans, bivalves, finfish) populations may be negative or positive. It is foreseeable that synergies may exist between climate change and other major stressors. Generally, finfish have the ability to actively migrate to avoid unfavorable conditions. However, if unfavorable conditions persist indefinitely, this creates an entirely new habitat that would have far-reaching ecological consequences. In the case of marine species that are being exploited in LIS, climate related impacts would be a result of temperature, low dissolved oxygen, and reduced pH (acidification). The severity of these impacts may be different at various life stages. Climate change places additional pressure on exploited marine fish stocks that are already subject to over exploitation and other stressors (Harley et. al, 2006).

D. Coastal Habitats of Long Island Sound and Associated Species/Systems

The coastal habitats associated with LIS include both estuarine and terrestrial systems and the numerous species associated with each. Terrestrial systems including coastal forests, shrublands, and grasslands will experience increased air temperatures causing changes in phenology, as well as distribution and abundance of species. Coastal bluffs and escarpments will likely experience increased erosion from stronger storm events as well as from increased precipitation and runoff. Additional climate-related changes that will likely impact these systems are changes in precipitation, changes in groundwater (including salinity and height of the groundwater table) and, depending on location, sea level rise. Marshes and intertidal systems and their associated plant and animal species will experience (or already are) experiencing impacts from sea level rise. Other climate related factors that will impact these areas include changes in salinity, precipitation, and groundwater flow. Subtidal communities are expected to be impacted by changes in salinity, sea level rise, pH, and increased precipitation and runoff can lead to increased nutrient loading and turbidity.

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