GASTROPOD SUBFOSSIL ASSEMBLAGES RECORD DECLINE OF CORAL REEF ECOSYSTEMS IN BOCAS DEL TORO, PANAMA

Human activities including overfishing, land use, and global climate change threaten to devastate coral reefs globally. This degradation of an important marine habitat has the potential to harmfully affect many marine communities and species; however, a lack of long-term ecological data makes it difficult to track the cause and extent of reef degradation through time. Previous work on the coral reefs in the Bocas del Toro region of Panama suggests that coral reef degradation in the Caribbean may have begun with changes in land use associated with the establishment of banana plantations in the late 1800s to early 1900s. These conclusions are largely based on the analysis of both coral and bivalve subfossil assemblages. We were interested in determining if other subfossil assemblages corroborated the observed ecological trends. To this end, we looked at gastropod subfossil assemblages from sediment cores collected at two coral reef sites in Bocas del Toro, Panama (Airport Point and Punta Donato). By tracking changes in gastropod assemblages through time, we hope to gain further insight into how Caribbean coral reef ecosystems changed through time and in response to different historical environmental stressors. We identified gastropods to the generic or family level and then assigned them to functional groups. 208 individuals were identified from the Punto Donato core, and 260 from the Airport Point core. In the Punto Donato core we observed a general decrease in abundance of carnivorous gastropods, such as Nassarius, and members of the family Columbellidae. The decrease in carnivorous gastropods is accompanied by an increase in herbivorous gastropods (e.g. Hemimarginula and Cerithium). This shift in the ratio of carnivores to herbivores may indicate a higher stress environment, and appears to have existed as early as European settlement in the region. The changes in the gastropod assemblages support the previous observation that these reefs experienced negative impacts from human activities long before reefs were actively monitored. In addition, our data suggests that the entire reef community – not only corals – can change in response to human activities.