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
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.
 | | Juliana Barrett, PhD
Barrett is an assistant extension educator at the Connecticut Sea Grant and NEMO programsWhy 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.  Back to top
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