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Globigerina bulloides
''Globigerina bulloides'' is a species of heterotrophic planktonic foraminifer with a wide distribution in the photic zone of the world's oceans. It is able to tolerate a range of sea surface temperatures, salinities and water densities, and is most abundant at high southern latitudes (up to 40° S), certain high northern latitudes (up to 80° N), and in low-latitude upwelling regions. The density or presence of ''G. bulloides'' may change as a function of phytoplankton bloom successions,〔NOAA ''National Geophysical Data Center'': ().〕 and they are known to be most abundant during winter and spring months.〔Deusser, W. G., Ross, E. H., Hemleben, C. and M. Spindler, 1981. "Seasonal changes in species composition, number, mass, size, and isotopic composition of planktonic foraminifera settling into the deep sargasso sea." ''Palaeogeography, Palaeoclimatology, Palaeoecology,'' vol.33 pp.103–127.〕
Like other planktonic foraminifera, ''G. bulloides'' carbonate tests found in marine sediments obtained from ocean cores can be used to reconstruct climatic histories, and to align marine sediment cores with one another or with astronomical cycles. In this vein, oxygen isotopic analyses of these forams from drill cores in the North Atlantic have helped precisely date the timing of the onset of northern hemisphere glaciations in the late Pliocene, 2.5–3 million years ago.〔Bartioli, G., Sarnthein, M., Weinelt, M., Erlenkeuser, H., Garbe-Scheonberg, D. and D. W. Lea, 2005. "Final closure of Panama and the onset of northern hemisphere glaciation." ''Earth and Planetary Science Letters'' vol.237 pp.33–44.〕 Magnesium to calcium ratios are also used in ''G. bulloides'' to reconstruct temperature histories in the world's oceans, as experimental cultures of the foram have shown magnesium to calcium ratios to increase exponentially with increasing ocean temperature.〔Lea, D. W., Mashiotta, T. A. and H. J. Spero, 1999. "Controls on magnesium and strontium uptake in planktonic foraminifera determined by live culturing." ''Geochimica et Cosmochimica Acta'', vol.63 no.16 pp.2369–2379.〕
==References==
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