Colloquium: Barbara Balestra

ABSTRACT:  Coccolithophores are one of the most abundant groups of extant phytoplankton, they are significant components of marine sediment, and they play a major role in marine primary production and the oceanic carbon cycle. Until about forty years ago, the vast majority of coccolithophore studies were focused primarily on taxonomy, zonation development, and applied biostratigraphy. More recently, the coccolithophore living and fossil record in the ocean and in the deep-sea sediments has been used in paleoceanographic studies. These studies include using extant coccolithophore assemblages as proxies for temperature and environmental change. In the fossil record, it is established to trace changes in the nannofossil assemblages that are strictly linked to variations in the physical and chemical properties of the waters such as salinity, turbidity, temperature, nutrient content etc. In particular, different coccolith taxa are known to be sensitive to specific environmental parameters.

The purpose of this seminar is to explain what these phytoplanktonic organisms are, why they are important and show how the coccolithophore assemblage variation can be used to characterize the dynamics of the different water masses in paleoceanographic studies. We will do this describing the International Ocean Discovery Program (IODP) and presenting results from the recent IODP Exp 339 (November 2011 to January 2012) in the Gulf of Cadiz and the West Iberian Margin. These regions are key locations for the investigation of Mediterranean Outflow Water (MOW) through the Gibraltar Gateway and its influence on global circulation and climate.