The relative abundance (%) of planktonic foraminifera over time in core MD032607, located off the coast South Australia

The advent of deep-sea drilling in the 1950's prompted the use of planktonic foraminifera (unicellular protozans) as palaeoceanographic indicators. They provide a natural archive of past environmental changes due to their global distribution, their prolific productivity and sensitivity to environmental variations.The highest species abundance of foraminifera in core MD032607 was recorded by Globigerina bulloides (~45%) during the penultimate glacial period (MIS 6) and, generally, was the most abundant with an average abundance of 19.5%. The dominance of the sub-polar, transitional species, Ga. bulloides in this core suggests the influence of cold, nutrient-rich water during certain isotopic stages. Conversely, the dominant warm and oligotrophic species Globigerinoides ruber recorded its lowest abundance in Marine Isotope Stage (MIS) 6, and is totally removed from the record (0%) at 146K, 142K, and 139K yrs BP.