Calcareous dinoflagellates are primary producers living in the photic zone of the oceans.
The study of surface sediment samples from the Arabian Sea has shown that the large spatial trends in abundance of the individual species can be related to the conditions in the upper 100m of the water-column, which are determined by the Asian monsoon system. The most important controlling factors seem to be water temperature, degree of stratification and nutrient concentration or related competition with other plankton groups. Furthermore, there is indication of different dissolution sensitivity among the individual species. We conclude that the recent distribution of calcareous dinoflagellate cysts in surface sediments of the Arabian Sea represents a combined signal of ecology and early diagenesis. The alteration of the primary signal is stronger in the NE of the working area.