Assessment of the Rhode Island coastal lagoon ecosystem

Kathryn Hale Ford, University of Rhode Island

Abstract

The health of the Rhode Island coastal lagoon ecosystem is of importance due to its critical role as a wildlife habitat and recreation destination. As human population continues to expand along the coast, this ecosystem will receive increasing pressure from contaminants. In order to understand how the ecosystem responds to such pressures, a multi-disciplinary approach was employed to gauge the extent and impact of chronic, low-level pollution, examine how the ecosystem has changed and will change over time, and to investigate methods to further our ability to monitor change. ^ Three coastal lagoons along the southwest coast of Rhode Island were selected for study: Ninigret, Quonochontaug, and Winnapaug Ponds. They represent a spectrum of conditions in terms of size, volume, and human population densities, yet they are all under similar pressures regarding future population increase and tidal inlet modifications. The distribution of organic and inorganic contaminants established that these lagoons are not well mixed despite how shallow they are. It was found that currently, these contaminant concentrations are too low to cause any significant biological impact. ^ Paleoproductivity studies were conducted in Quonochontaug and Garden Ponds. Lithofacies associated with hurricanes were identified. The physical disruption or salinity alterations associated with hurricanes appeared to have minimal impact on long term trends. However, sedimentation of the lagoon's tidal inlet leads to a freshening of the lagoon and higher productivity. In contrast, a dredging project, which opened the tidal inlet, led to an increase in salinity within the lagoon and a decrease in productivity. Anoxia was documented during a period when the tidal inlet was closed. ^ Lastly, side-scan sonar technology was optimized to accurately map critical geologic environments and biologic habitats in Quonchontaug Pond in order to provide a baseline to study future habitat alterations. The 500kHz side-scan survey was adequate to identify eelgrass beds. Areas with boulders were at times hard to differentiate from the eelgrass, necessitating thorough groundtruthing with underwater video and sediment grab samples. This method holds potential for developing accurate estimates of eelgrass bed areal coverage. Approximately eighty acres of eelgrass were present in the lagoon. ^

Subject Area

Biology, Ecology|Biogeochemistry|Paleoecology|Environmental Sciences|Geochemistry

Recommended Citation

Kathryn Hale Ford, "Assessment of the Rhode Island coastal lagoon ecosystem" (2003). Dissertations and Master's Theses (Campus Access). Paper AAI3115628.
http://digitalcommons.uri.edu/dissertations/AAI3115628

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