RELATIONSHIP BETWEEN MARINE ENVIRONMENT, PREDATION INTENSITY, AND BIVALVE COMMUNITY DIVERSITY FROM THE TAMIAMI, CHIPOLA, JACKSON BLUFF, AND BERMONT FORMATIONS OF FLORIDA, USA

The Late Cenozoic paleoenvironment of Florida was quite dynamic with multiple short episodes of climate change and environmental shifts affecting all fauna. Florida experienced intense deep-water cooling that resulted from global cooling and growth of the East Antarctic ice-sheet in the middle Miocene continuing into the Pliocene. These environmental changes had vast impacts on the bivalve communities during the Late Cenozoic and influenced predation rates on bivalves. This study evaluated the trends in both predation and biodiversity of bivalves during the dynamic late Cenozoic record within the Chipola, Tamiami, Jackson Bluff, and Bermont formations. Shifts in predation rates and bivalve diversity were evaluated over short timescales within the Bermont Formation and over longer timescales in the Chipola, Tamiami, and Jackson Bluff formations. Shifts in diversity and predation on very short timescales were reflected in bivalve assemblages within different beds of the Bermont Formation. Long and short term changes in bivalve composition and predation were evaluated in the context of climate change and sedimentary environment. The relationships between predation and diversity shifts within the Bermont Formation are reflected in diversity, abundance, and rate of boring. There were measurable differences between and among the long term studies in abundances, greater diversity, and shifts correlated with climatic shifts as well as overall variations in predation intensities. The Tamiami Formation represented lower overall abundances, higher levels of diversity, and low predation within each species. However, the lower Bermont Formation exhibited higher abundances, lower overall diversity, but moderate predation. The Jackson Bluff expressed high abundances, low diversity, and high levels of predation. The Chipola Formation contained high abundances, moderate diversity, but very low predation.