Late Quaternary Protoperidinium cysts as indicators of paleoproductivity in the northern Arabian Sea

The reliability of organic-walled cysts of the heterotrophic dinoflagellate Protoperidinium as paleoproductivity indicators and the influence of bottom water oxygenation on cyst preservation is assessed by using Arabian Sea records of the past ∼125 kyr as a natural laboratory. Multidisciplinary geochemical, micropaleontological and palynological datasets are integrated to analyze the relationship between Protoperidinium cyst concentrations and other paleoproductivity proxies. Differential preservation potential is quantified in order to establish threshold oxidative degradation values for a possible application of quantitative Protoperidinium cyst records in paleoenvironmental reconstructions. Results indicate that variations in Protoperidinium cyst concentration closely correspond to other marine productivity and/or upwelling proxies. Although oxygenation will lead to significant cyst degradation, and thus decreased concentrations, down-core patterns in Protoperidinium cyst concentration still primarily reflect changes in sea surface productivity. In view of differential preservation among dinoflagellate cysts, down-core variations in relative abundance of Protoperidinium should be treated with caution.