GASTROPOD COMMUNITY CHANGE WITHIN THE CAYO AGUA FORMATION, PANAMA, DURING CLOSURE OF THE CENTRAL AMERICAN SEAWAY

During the Pliocene (~3.5 MA), the Central American Seaway closed, resulting in a narrow strip of land between the Caribbean Sea and the Pacific Ocean, now called the Isthmus of Panama. This closure ultimately caused regional oceanographic changes; in the western Caribbean, these changes included an increase in mean annual temperatures and salinity, as well as a decline in upwelling and planktonic productivity. These environmental changes resulted in taxonomic turnover and an alteration of benthic community structure. Fossils from the Caribbean provide a record of these ecological changes through time.

This research focuses on gastropod shells from the Cayo Agua Formation, Bocas del Toro, Panama, which spans the transition period (5-3 Ma). By conducting a study of communities during this transitory period, our aim is to understand how gastropod communities responded to ecological and environmental changes during this time. More specifically, we identified the gastropods to genera, and then assigned genera to trophic group (e.g. active carnivore, browsing herbivore, etc.) to determine ecological changes. Previous work has hypothesized that as planktonic productivity decreased in the Caribbean, the number of predatory or carnivorous gastropods also decreased. By looking specifically at this constrained time period and geographic location, we can learn how quickly ecological turnover took place. Exploring the response of gastropod communities to environmental perturbation will help us to better understand the evolutionary history of Caribbean marine communities. More generally, understanding ecological response to environmental perturbations has a broad range of applications that can help scientists better understand how biological communities respond to environmental impacts.