Mussels, barnacles, and algae known as rockweeds are the major structural components of natural communities that line the shore in the Gulf of Maine and form the home for many species of fish and invertebrates. The long-term goal of this project is to determine whether the factors that switch a rockweed community into a mussel-barnacle bed are random (stochastic) or determined by site-specific characteristics (deterministic). Ice scour, which removes rockweed, mussels, and barnacles from the shore, has been suggested as the event that can switch a rockweed stand into a mussel bed and vice versa. In ecology, the idea that the same kinds of sites could be occupied by different types of communities is commonly referred to as the 'theory of alternative stable states.' If algal stands and barnacle-mussel beds are alternative states, then removal of one or the other should initiate the switch. If local site-specific differences are important, then communities should return to their original state. To examine these possibilities experimentally, openings in rockweed stands or mussel-barnacle beds, which mimic the effects of ice scour, will be initiated and monitored. Experiments of this type that were started in 1996 provide one of the longest experimental studies of the theory of alternative stable states, but the experimental sites are still changing and it is not clear if the final communities will return to rockweed stands or become mussel beds. LTREB support will provide funds to continue monitoring for additional five years. This study has implications for the management of marine ecosystems; if the natural communities found on the shores of the Gulf of Maine exist as alternative states, then management strategies dealing with fisheries, development and man-made disasters may need to account for the potential for small environmental insults to cause large irreversible changes. Research will also enhance the understanding of science and research by involving K-12 students and teachers, and undergraduates. Data collection, data entry, and some basic analysis will be done with the help of middle school students from Portland, ME and undergraduates from Philadelphia, PA. A high school science teacher will be supported as a field assistant during the summers. A web page will be developed K-12 students and aimed at introducing the students to experimental marine ecology. The site will provide specific questions for students, and data summaries will be available for the students to answer these questions.
