Sound Health 2008 is our report to the public on the environmental issues affecting Long Island Sound. It provides information on water quality, the abundance of animal and plant life in the Sound, and trends in land use along the shore.
To view the full Sound Health 2008 report, download the pdf document
Climate change is often seen as a national and international concern, but it is very much a local issue as well. Temperatures are rising in Long Island Sound, and those increases already have resulted in changes to the Sound. What are these changes? LISS asked area scientists to assess the impact of climate change in the Sound, and what the Sound might experience in the future.
Dr. Elphick is a conservation biologist at the Department of Ecology & Evolutionary Biology, University of Connecticut.
How can sea level rise affect the population of the saltmarsh sharp-tailed sparrow and the seaside sparrow? The main cause of nest failure in saltmarsh sharp-tailed sparrow is nest flooding, so rises in sea-level are expected to increase the rate at which nests are lost unless marsh elevations increase or marshes are able to move inland. Neither of these marsh changes seems likely to happen fast enough to match sea-level rise, although our research on the likely speed of the population changes is not complete. Both species are also specialists in salt marsh habitats, and the loss of these habitats due to sea-level rise will reduce the area of habitat available. This change is likely to affect both species, but especially seaside sparrows, which only occur in a few large marshes in Connecticut.
What will be the effect of continued warming on the diversity of wildlife that live along the Sound’s shoreline? This question is difficult to answer. Some southern species might become more common. For example, boat-tailed grackle and black skimmers have both colonized the state in recent years and seem to be increasing. But, several species for which the state plays an important conservation role—such as saltmarsh sharp-tailed sparrow and piping plover—are likely to suffer as their habitats become prone to increased flooding and birds are confined to smaller areas. The biggest problem is that climate change and sea-level rise will come on top of the existing effects of habitat loss along the shore. Consequently, species that are already in a precarious state will have to deal with an additional set of problems. Ultimately, large-scale land use planning and better long-term monitoring of the state’s biological diversity are the best way to address all of these issues.
Ron Rozsa is a coastal ecologist with the Connecticut Department of Environmental Protect.
What is the relationship between sea level rise and tidal wetlands? Tidal wetlands formed in Long Island Sound as the expansive ecosystems we know today about 3000 years ago when sea level rise slowed to a rate of 1 mm/yr. In the late 1800s, the rate in LIS changed from 1 to 2.5 mm/yr. During this period, at least in the western Sound with the highest tide range, there has been the gradual drowning of low marsh. In the last 10 years, increased sea level rise rates are causing a variety of vegetation responses such as the migration of black grass (Juncus gerardii) onto adjacent uplands, a process called marine transgression. The seaward edge of high marsh grasses appear to be drowning in some marshes and the low marsh cord-grass (Spartina alterniflora) is colonizing the high marsh.
Scientists have called tidal wetlands one of the most productive habitats on earth. What can we do in order to try to protect it from sea level rise? Various studies on global warming conclude that sea level rise will accelerate, but the amount of that acceleration depends upon future greenhouse gas inputs into the atmosphere. In order to protect vulnerable habitats such as tidal wetlands, it is critical to mitigate climate change by reducing greenhouse gas emissions, but also to develop and implement adaptation strategies. Examples of adaptation strategies for tidal wetland restoration include favoring high marsh elevations to accommodate some sea level rise and site selection favoring restoration projects that are adjacent to low–lying uplands, allowing for marine transgression in the future. Another example is harvesting the seeds of vulnerable plant species and storing these seeds in a seed bank to allow their reintroduction to tidal marshes in the future under more favorable sea level rise rates.
Dr. Barrett is an assistant extension educator at the Connecticut Sea Grant and NEMO programs
Why would you expect Phragmites, an invasive species, to increase if temperatures are rising? Climate change in the northeast may lead to an increase in the frequency and intensity of coastal storms. Increased freshwater as a result of more rain may temporarily decrease salinity levels enough to allow Phragmites australis, which does not tolerate high salinity, to spread. Alternatively, sea level rise, due to water expansion from increased temperatures, may over time either drown our coastal marshes or cause marshes to migrate landward – where sufficient low lying undeveloped land exists for such movement. In situations where marshes are able to migrate landward with sea level rise, the likelihood of invasion by Phragmites increases as marsh migration encounters land uses that promote changes such as decreased salinity levels or increased drainage of marshes.
Why is Phragmites a problem for tidal wetlands? Research has demonstrated that there is both a native and introduced type of Phragmites australis in North America. In Connecticut, the native type is found in brackish tidal marshes where it grows interspersed with other vegetation. The introduced type tends to form large, dense stands in a variety of wetland systems. These dense stands crowd out other vegetation, changing both the flora and fauna of these areas, as well as often changing the nutrient cycling and hydrology of these wetlands.
Dr. Conover is Dean of the School of Marine and Atmospheric Sciences, Stony Brook University.
Increased carbon dioxide in the atmosphere leads to an increase in carbonic acid in the ocean, making oceans more acidic. Why is this a concern? Most of our knowledge of the direct effects of ocean acidification on marine organisms focuses on species known as “marine calcifiers” (e.g., corals, mollusks) that build skeletons or shells made of calcium carbonate. Many of these species will suffer from an impaired ability to build skeletons as too much carbon dioxide produces carbonic acid, which corrodes shells. We know less about the direct impacts of acidification on harvested species like fishes and squids. In these species, the response to acidification is likely to involve physiological diseases including acidosis of tissue and body fluids leading to impaired metabolic function. Egg and larval stages are likely to be much more susceptible than adults, suggesting that reduced reproductive success will be among the first symptoms to appear.
Why is “ocean warming” a concern? All species are adapted for life over a relatively moderate range of temperatures compared with the extremes experienced from the poles to the tropics. Temperatures below the optimal range slow the rate of metabolism and can become lethal if too low. Temperatures above the optimal range increase metabolism and, because warmer water contains less dissolved oxygen, a thermal threshold is reached where respiratory demand exceeds the capacity for oxygen uptake. This is sometimes referred to as the “temperature oxygen squeeze.” Hence, temperature is one of the primary environmental factors that determine the geographic range of a species.
What is the impact to Long Island Sound? Most of the cold-water species of Long Island Sound have been declining over the past 15 years (e.g., lobster, winter flounder, Atlantic herring, cunner, longhorn sculpin, sea raven, ocean pout, winter skate, and little skate), while most of the warm-water fishes have been increasing (e.g., striped bass, weakfish, summer flounder, menhaden, scup, striped sea robin, butterfish, Atlantic moonfish, hickory shad). Finally, there is also evidence from Long Island Sound that the recent trend of warmer winters favors the growth and recruitment of invasive species over those of native species. Researchers from the University of Connecticut showed that exotic ascidian species (sea squirts) benefit more from mild winters, while native species benefit more from cold winters.
What preventive measures should be taken? Resource managers need to recognize that local populations of species near the limits of their distributional ranges will need additional precautionary measures to protect them from extinction. Warming and acidification represent additional stresses that make populations less resilient to the effects of harvest. We may need to reduce harvest of some species in certain areas to enable them to withstand the additional stress. The ultimate and best solution is the reduction of greenhouse gases that cause acidification and warming.
Dr. Rosenzweig is a research scientist at the NASA Goddard Institute for Space Studies (GISS) and Columbia University. She currently leads the Climate Impacts Research Group at GISS, with which she has been affiliated since 1984. For more information about Columbia’s program visit http://ccsr.columbia.edu/resources/index.html
What have been the water temperature and sea level rise trends over the past 100 years, and what is projected in the next 25, 50, and 100 years? Between 1979 and 2002, sea surface temperature at two locations in the eastern Long Island Sound has been observed to increase by approximately 1°C (1.8° F). This warming affects marine ecosystems, from plankton up to lobsters.
Over the past century, sea levels have been rising in the New York Metropolitan region by about an inch per decade.
Recent research based on global climate models suggests a possible range of regional sea level rise of 2.5 to 7 inches in the next 25 years, 6 to 15 inches in the next 50 years, and 1 to 3 feet in the next 100 years.
These projections are uncertain, however, in part because climate models cannot currently tell us how ice sheets may respond to increasing temperatures. If melting of ice sheets accelerates, sea level rise will likely be higher.
How does an increase in temperature affect sea level rise? Increasing ocean temperatures cause ocean water to expand, leading to higher sea levels. Increasing air temperatures can cause sea level to rise, either indirectly by causing ocean warming or directly by melting land ice that then flows to the sea. The situation is made even more complex by the role of atmospheric temperature change in modifying the balance of precipitation and evaporation over land and ocean.
What are the implications of continued sea level rise in Long Island Sound, and what do we need to do to adapt if this trend continues? Rising seas in Long Island Sound may increase the intensity, duration, and frequency of high water levels associated with coastal storm flooding. Coastal flooding threatens natural ecosystems as well as commercial, civil, and residential infrastructure and assets. Flooding can also cause groundwater pollution. A range of possible adaptation measures should be considered, including building seawalls, restoring wetlands to act as natural buffers, and modifying coastal development policies.
From June – October 2007, naturalist Laurie Sanders produced eight radio features focusing on the health and diversity of Long Island Sound for her Field Notes program on 88.5 FM WFCR (public radio of western New England). An estimated 200,000 listeners heard the reports on WFCR and on public radio stations in Connecticut.
These six minute reports with scientists, environmentalists for non-profit groups and government resource managers are now available as podcasts on this web page.
The audio clips are keyed to related content in the [intlink id=1422]2008 Sound Health report[/intlink].
Instructions: Click the track link you would like to listen to. In most instances, left clicking will start the audio file which right clicking will allow you save the file for playback on other devices including Ipods and mp3 players.
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