Lake system response to Caribbean hurricane activity – a calibration study of ostracode (paleo-)biology and geochemistry (Lago Enriquillo, Dominican Republic)

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Tropical cyclones (TCs) are one of the most devastating natural disasters causing immense death tolls and monetary loses. TC impacts are particularly strong in developing countries such as many of the Small Island Countries in the Caribbean. Currently, instrumental data about TC-activities are available only for the last ~150 years which is too short to achieve an understanding of the long-term variability of TC activities and its main forces. Improved future prospections of TC occurrences require therefore longer proxy records from natural archives. So far, are overwash deposits in coastal lagoons most commonly utilized for the identification of past hurricane landfalls. However, these deposits have a small spatial distribution and a limited preservation potential. In contrast, closed-basin lakes represent continuous and high-resolution archives for large-scale precipitation events. The closed basin lake Lago Enriquillo in the Dominican Republic is situated in the Main Development Region (MDR) of TCs. The saline lake lies in a semi-arid region and is characterized by strong seasonal contrasts in precipitation, intense evaporation, and severe TC impacts. The resulting rapid lake level fluctuations and salinity changes prove that the lake is a key site for the development of novel geochemical and biological proxies for TC-related precipitation extremes. TCs produce large amounts of precipitation with distinctly lower oxygen isotope values (`amount effect´) than low-latitude thunderstorms and `normal´ precipitation. We propose to refine and improve a stable isotopes-based (δ18O) approach for the reconstruction of paleo-TCs. The integration of ecological and morphological data of modern ostracodes in combination with seasonal changes in hydrochemistry will be used to calibrate δ18O and δ13C values of calcareous ostracode valves. This is the prerequisite to understand how changes in precipitation/evaporation and influences of TCs are reflected in ostracode species assemblages (species composition, population structure, morphological variability) and their δ18O and δ13C values. These findings will be used to reconstruct precipitation/evaporation and TC activities during the past centuries based on fossil ostracode species assemblages and ostracode δ18O and δ13C compositions from short sediment cores.