USGS scientists publish results from a long-term study of Globigerinoides ruber in the Gulf of Mexico, aiding in reconstruction of past climatic conditions

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The planktic foraminifer, Globigerinoides ruber, is the most widely used proxy recorder for reconstructing past temperature and salinity in the low to mid-latitude oceans.

USGS scientists have had a sediment trap mooring in the northern Gulf of Mexico for the past decade, 2008–2019, to investigate seasonal and inter-annual variations in the flux and morphometry in addition to the isotopic and trace metal geochemistry of this geologically important species. This study shows that two chromotypes of this species (pink and white) can be used interchangeably to reflect mean annual surface ocean conditions. This study also demonstrates that the canonical 9% increase in shell Mg/Ca per 1ºC increase in temperature is an overestimate of temperature sensitivity, and that pH has an important influence on Mg/Ca-derived ocean temperature records in this species. Partners in the study include University of Texas at Austin, University of Southern California, and Brown University.

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photos of sediment sampling, the R/V Pelican, and sediment analysis

Samples are recovered from the sediment trap once every 9-12 months. Cruises to recover and redeploy the mooring take place on the UNOLS vessel, R/V Pelican, operated by LUMCON, in Cocodrie, Louisianna. On these cruises water is collected for isotopic and trace metal analysis, as well as to measure parameters of the carbonate system (dissolved inorganic carbon, total alkalinity, pH). Sometimes live foraminifera are collected with a plankton net for additional geochemical and genetic analyses.

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Date published: February 27, 2018
Status: Active

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