CHANGES IN TROPHIC STRUCTURE OF NEOGENE GASTROPODS FROM THE SOUTHWESTERN CARIBBEAN

Understanding the mechanisms by which physical changes in the environment can impact biological communities is important for deciphering and predicting how systems have and continue to function in our rapidly changing world. One way to explore these mechanisms is by examining the response of ancient communities to past physical system changes. In the Neogene Caribbean, these changes impacted the structure of benthic communities, where faunal turnover following environmental change led to restructuring of older communities and the emergence of the modern Caribbean fauna. While previous workers have detailed the response of many groups to the environmental changes associated with the closure of the Isthmus of Panama, including corals, bryozoans, and bivalves, changes in the gastropod community are less understood.

Here, we quantify relative abundances of gastropod trophic groups across seventy bulk sampling locations in Panama and Costa Rica. Samples ranged in age from 11 million years to ~7000 yrs. We identified individual specimens to the genus level, and then assigned each genus to a trophic group based on diet, mobility, and relationship to the substrate, as defined in the Neogene Marine Biota of Tropical America (NMITA) database. Previous work on gastropod ecology suggests that declines in abundance of carnivores and suspension feeding gastropods are expected over time, as productivity decreased in the Caribbean. Our data supports this hypothesis. Developing a strong understanding of changes in these regional communities can help contribute to understanding of how the mechanisms that link environmental and biological changes operate.