"Do Gastropod Subfossil Assemblages Show Anthropogenic Impacts on Coral Reefs in Bocas Del Toro, Panama?"

Claire Sbardella, Thesis 2017

Abstract: 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, for example through habitat loss and lowered oxygen levels. While current decline of coral reef ecosystems is well documented, 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 of 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. This work has principally focused on changes observed in the coral and bivalve assemblages from sediment cores. Trends in the ecology of major bivalve functional groups support and provide additional information to data obtained from the coral assemblages themselves. I was interested in determining if other subfossil assemblages corroborated the ecological trends seen in the bivalves. To this end, I 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 over time, I hope to gain further insight into how these coral reef communities changed through time and in response to different historical environmental stressors. I identified gastropods to the generic or family level and then assigned them to functional group, and then tracked their changes through time. Analyses of individual cores demonstrate no significant change in functional groups throughout time. A combined analysis of all four cores shows a significant fluctuation in Carnivores over time, but no other significant changes. I have determined that this type of analysis as it stands is not sufficient enough to reliably reflect changes in coral reef ecosystems. Obtaining a greater sample size of gastropods may rectify this problem, with continued emphasis on the use of bivalves, which may be more sensitive to ecological changes than gastropods.

Full thesis available. Contact the Geology Department at 540-458-8800.