GEOGRAPHIC VARIATION IN ENVIRONMENTS AND EXTINCTION IN THE CARIBBEAN

University Of California-San Diego Scripps Inst Of Oceanography, La Jolla CA

Investigators

Abstract

Geographic Variation in Environments and Extinction in the Caribbean Jeremy B. Jackson University of California, San Diego, Scripts Institute of Oceanography This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5). Understanding the causes of major extinction events is often hampered by a lack of rigorous environmental and biological data and limited geographic coverage, which can help determine how closely events in one region are mirrored in others. The PI proposes to document patterns of environmental and evolutionary change in the Northern Caribbean (NC; Jamaica and the Dominican Republic) over the past ten million years and compare these patterns with similar data already obtained from the southwestern Caribbean (otherwise the SWC), including Panama and Costa Rica. The SWC experienced a dramatic decrease in seasonal upwelling and productivity due to the rise of the Panamanian Isthmus, and detailed evolutionary studies of bryozoans and scallops strongly support the hypothesis that decline in productivity was responsible for the very high extinction and speciation in these groups. Previous taxonomic studies suggest that extinction was comparably strong and occurred at about the same time in the NC, but the very limited data available suggest that there may not have been an equivalent drop in productivity. This study will provide the first detailed environmental and biological data to document the sequence of changes in the NC. Data will be entirely comparable with those from the SWC because they will be collected and analyzed using the same methods and criteria. Results will provide a definitive test of the productivity hypothesis over a broad region. If productivity did decline in the NC there will be little need to look for alternative explanations. But if productivity did not decline, then other factors must also have played an important role in Caribbean extinction. Possible alternatives include oceanographic changes due to regional cooling or increased rates of rise and fall of sea level associated with the intensification of Northern Hemisphere glaciation that occurred about one million years after the closure of the Panamanian Portal. The project is highly feasible because extensive geological and paleontological investigations over the past 25 years have provided the necessary stratigraphic framework to begin to fit all the different pieces of the story together.