Continued invasion of the green mussel in established seagrass meadows and potential seagrass areas could eventually have a devastating impact on the seagrass habitat and the overall function of the Tampa Bay ecosystem. An urgent need exists to understand the extent and the rate of the invasion of seagrass areas, and its potential long-term impacts to the ecosystem. In a proposal to the Tampa Bay Estuary Program (TBEP), the BSG offered to conduct a pilot research study to evaluate the current invasion of green mussels in Hillsborough Bay, specifically in areas with seagrass coverage and potential areas of seagrass colonization. Two anticipated and potentially counteracting influences to the seagrass meadows from the green mussel invasion will be examined. First, the negative impact to seagrass growth and area coverage caused by direct displacement from suitable substrates by the green mussels will be evaluated. Second, potentially positive effects to seagrass areas, located near green mussel beds as a result of the feeding activity of the mussels, will also be examined This report constitutes an interim report provided to the Tampa Bay Estuary Program (TBEP) to describe progress on the project to date.