Changing Habitats: Settlement of Non-Native Marine Species

By Nicole MisA project exploring the abundances of native and nonnative species in New England is underway by MIT Sea Grant College Program researchers Judith Pederson, PhD and Carolina Bastidas, PhD. Nonnative species are identified as a major cause in the alteration of habitats and biodiversity and has detrimental economic impacts. This project is designed to improve our understanding of how nonnative species change ecosystem dynamics and often become competitively dominant. The first year study is devoted to examining the timing and rate of species settlement over the course of a year. Measuring the spatial coverage of native and non-native species over time in newly created open spaces is the first step in elucidating settlement dynamics in nature. Future studies will look into competitive interactions between and among native and non-native species to gain insights into why nonnative species are more successful than their native counterparts. During the first year, PVC plates were deployed at two locations in Massachusetts waters, New England Aquarium, Boston Harbor and at the Massachusetts Maritime Academy, Buzzards Bay. The plates will be in the field for one, two and three month intervals to compare the rate of settlement on bare substrate (month 1) and on developing communities (month 2 and 3). Immediately after retrieval, the plates are photographed and the plates are transported to the lab where the individual species are identified to genus or the lowest possible taxonomic group. Using Image J (an open source processing program), a digital grid is superimposed onto a picture of each plate to calculate percent cover to permit an estimation of the abundance of the organisms. Early results record both native and non-native species are settling on open spaces, including non-native tunicates (sea squirts), native hydroids (animals related to sea anemones), amphipods (small crustaceans), barnacles, mussels and algae. The data from this study will assist managers in their efforts to prevent, manage and control non-native species that arrive by shipping and related human activities.