| Summary: | Statement: Foraminifera were identified accurately to a species level, with an average of 437 individuals picked and identified per sample. Relative species abundances are calculated as a percentage of the total count. Parameters: Age of core (yrs BP), relative abundance of planktonic foraminifera assemblages (%). Statement: Counts of planktonic foraminifera were made on splits of the >150µm fractions to provide a base level for ecological counts, removing small juvenile and possibly unidentifiable foraminifera. Each sample was split by an Otto-micro splitter until ~400 species were present in the final split. Credit The Australian National University (ANU) Credit Funded by The National Oceans Office (NOO) Credit Funded by The French Polar Institute Credit Funded by The Australian Institute of Nuclear Science Engineering (AINSE) Credit Funded by The Australian Research Council (ARC) Credit Funded by The Murray Darling Basin Commission Purpose To reconstruct the faunal assemblages of planktonic foraminifera through time and give insight into palaeoceanography of core location. 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 most obvious change in relative abundance in core BAR9403 (off the coast of Sumatra) is shown by sub-polar to transitional 'upwelling' species Ga. bulloides with abundances of 26% at approximately 14,000yrs BP and 22.7% during the Holocene. This is compared to the periods from Marine Isotope Stage (MIS) 3 to the Last Glacial Maximum (LGM) where the relative abundance of Ga. bulloides is generally <10%. Gr. menardii, a tropical 'upwelling' species, also increases its relative abundance during MIS 2 from <8% during MIS 3 to a peak abundance of 16% at ~17,000yrs BP.
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