Identifying Sites for Successful Eelgrass Restoration in Narragansett Bay , Rhode Island

Monica Candal

Brown University, Sc.B. May 2005

Humans have greatly altered the environment of Narragansett Bay , Rhode Island , gradually reducing species populations to their current critical state. In particular, eelgrass, Zostera marina , a species important for the habitat that it provides, has been severely affected. A wasting disease in the 1930's decimated North Atlantic eelgrass populations, which were unable to recover in Narragansett Bay due to habitat degradation caused by increased human population in the area.

In order to combat the problem, Save The Bay, Inc., a local non-profit group, has recently begun efforts to restore eelgrass sites by transplanting eelgrass shoots from natural beds to sites deemed suitable for restoration. Though much can be improved, the organization has led one of the most successful eelgrass restoration efforts to date in Narragansett Bay .

This study seeks to amplify current efforts in Narragansett Bay by employing a holistic approach to site suitability. Six sites (three large-scale transplants and three test transplants) were evaluated based upon the following criteria: depth, sediments, current velocity and light, which is based upon the results of two models—the Chesapeake Bay Model (CBM) and the Narragansett Bay Eelgrass Restoration Site Selection Model (NBERSSM). Sites meeting at least four out of the five listed criteria were considered suitable for restoration. All large-scale transplant sites and two transplant sites met at least four out of five of the study's criteria.

No single factor used in this study accurately predicted site success or failure of eelgrass transplantation at a site. Predictability improved, however, by combining factors. This study's results agreed with most of the survival data available for 2004; however, it did not accurately predict success or failure for all sites. Fogland Point, in particular, met the study's criteria and yet failed to meet the survival requirement (50%). This suggests that other factors not considered in this study may be affecting eelgrass transplantation success.

Based upon the results, large-scale transplants at Providence Point and Coggeshall Point are highly recommended. With current legislation to reduce nutrient inputs into Narragansett Bay by 50%, the future of eelgrass restoration looks promising. Furthermore, the employment of collective models is recommended to aid the efficiency of these restoration efforts.