Globorotalia truncatulinoides Sediment Trap Data in the Gulf of Mexico

Modern observations of planktic foraminifera from sediment trap studies help to constrain the regional ecology of paleoceanographically valuable species. Results from a weekly-resolved sediment trap time series (2008–2014) in the northern Gulf of Mexico demonstrate that 92% of Globorotalia truncatulinoides flux occurs in winter (January, February, and March), and that encrusted and non-encrusted individuals represent calcification in distinct depth habitats. Individual foraminiferal analysis (IFA) of G. truncatulinoides tests were used to investigate differences in the elemental Magnesium/Calcium (Mg/Ca) and isotopic composition (δ18O and δ13C) of the encrusted and non-encrusted ontogenetic forms of G. truncatulinoides, and to estimate their calcification depth in the northern Gulf of Mexico. Estimates show that non-encrusted and encrusted G. truncatulinoides have mean calcification depths of 66 ± 9 meters and 393 ± 83 meters, respectively. The Mg/Ca-calcification temperature relationship was validated for G. truncatulinoides and demonstrated that the δ18O and Mg/Ca of the non-encrusted form is a suitable proxy for winter surface mixed layer conditions in the Gulf of Mexico. Care should be taken not to combine encrusted and non-encrusted individuals of G. truncatulinoides for down core paleoceanographic studies.