Batiacasphaera Micropapillata: Palaeobiogeographic Distribution And Palaeoecological Implications Of A Critical Neogene Species Complex

The extinct dinoflagellate cyst complex Batiacasphaeramicropapillata (B. micropapillata, B. minute) has been frequently reported from Neogene sediments of the North Atlantic region, but little is known about its palaeoecology. To utilize it for future palaeoenvironmental interpretations, distribution maps for Middle Miocene-Pliocene time slices have been generated by using new data from Ocean Drilling Program (ODP) Hole 907A (Iceland Sea) and Integrated ODP (IODP) Hole M0002A (Central Arctic Ocean) and recent publications. This species complex is adapted to outer-neritic to oceanic environments, judging by its abundance at many deep-water sites in comparison to marginal marine settings and the co-occurrence of well-known oceanic species. The centre of distribution is the high-latitude North Atlantic, but it tolerates a range of sea-surface temperatures from 7-10 degrees C to >20 degrees C. The relatively low concentration in the Arctic Ocean represents an occurrence close to its ecological limit, and suggests that it may occur in regions with pronounced seasonal gradients in temperature, sea-ice and light. Increased nutrient availability may be a another important ecological factor under optimum living conditions. A distinct Late Miocene decline in the Iceland Sea and Arctic Ocean and a near-synchronous Pliocene disappearance in the North Atlantic suggest a response to Late Cenozoic cooling.