Extremely well-preserved plant and animal fossils from flooded limestone caves or "blue holes" in the Bahamas provide unparalleled evidence of environmental change over the past five or more millennia. A diverse assemblage of fossil plants, invertebrates, and vertebrates recovered recently from blue holes on the island of Abaco reveals a unique prehistoric terrestrial ecosystem with tortoises as the top herbivores and crocodiles as the dominant predators (rather than mammals, as on continents). This research project will examine long-term ecological change on the islands of Abaco and Eleuthera in order to assess how prehistoric and contemporary plant and animal communities responded to long-term environmental fluctuations, including cultural impacts following the arrival of humans about 1,000 years ago. This project is motivated by two broad, related sets of research questions. First, what were the relative influences of climatic changes vs. human influences in this well-controlled island research setting, and how does this study offer methodological and interpretive insights for distinguishing between these causes in ecological studies elsewhere? Coordinated, multidisciplinary reconstructions of long-term environmental change will consider whether terrestrial ecosystems in the northern Bahamas were resilient in the face of climatic fluctuations but experienced profound impacts with cascading effects following the prehistoric arrival of humans. Dated records of charcoal, pollen, spores, plant macrofossils, and animal fossils will indicate rates of biotic change both before and after human arrival. The second motivating question is: What are the impacts of modern land use on terrestrial biotic communities? The composition and distribution of existing plant and animal communities will be assessed, because they reflect altered resilience as a legacy of both prehistoric and historic land use. The interpretation of long-term trajectories of ecological change on Abaco and Eleuthera will facilitate the differentiation of the biotic effects of climate change vs. the combination of climate change and human impacts in the Bahamas, with larger implications for separating these causes elsewhere around the globe.
This project will provide a basis for predicting the responses of Bahamian and other island ecosystems to climatic and human-related perturbations. In particular, the assessment and management of worldwide biodiversity loss depend on an improved understanding of the dynamics of ecosystems at local and regional geographical scales as well as short and long time frames. Analyses of Bahamian terrestrial ecosystems will provide insights into changing resilience, biodiversity, and ecosystem function resulting from a suite of disturbance regimes, including extreme climatic events, hurricanes, fire, and land-use change. Through a broad network of public and private collaboration in the Bahamas, this project will enhance international scientific collaboration and develop a rigorous program of formal and informal science education, including internships for university students, public field trips and lectures, participation by citizen scientists, and development of educational brochures. The project also will generate an approach to conservation planning and land management grounded in biogeographic and ecological history and prehistory.