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Ecological controls on the shell geochemistry of pink and white Globigerinoides ruber in the northern Gulf of Mexico: implications for paleoceanographic reconstruction

Marine Micropaleontology

By:
, , ,
DOI: 10.1016/j.marmicro.2011.10.002

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Abstract

We evaluate the relationship between foraminiferal test size and shell geochemistry (δ13C, δ18O, and Mg/Ca) for two of the most commonly used planktonic foraminifers for paleoceanographic reconstruction in the subtropical Atlantic Ocean: the pink and white varieties of Globigerinoides ruber. Geochemical analyses were performed on foraminifera from modern core-top samples of high-accumulation rate basins in the northern Gulf of Mexico. Mg/Ca analysis indicates a positive relationship with test size, increasing by 1.1 mmol/mol (~ 2.5 °C) from the smallest (150–212 μm) to largest (> 500 μm) size fractions of G. ruber (pink), but with no significant relationship in G. ruber (white). In comparison, oxygen isotope data indicate a negative relationship with test size, decreasing by 0.6‰ across the size range of both pink and white G. ruber. The observed increase in Mg/Ca and decrease in δ18O are consistent with an increase in calcification temperature of 0.7 °C per 100 μm increase in test size, suggesting differences in the seasonal and/or depth distribution among size fractions. Overall, these results stress the necessity for using a consistent size fraction in downcore paleoceanographic studies. In addition, we compare downcore records of δ18O and Mg/Ca from pink and white G. ruber in a decadal-resolution 1000-year sedimentary record from the Pigmy Basin. Based on this comparison we conclude that pink G. ruber is calcifying in warmer waters than co-occurring white G. ruber, suggesting differences in the relative seasonal distribution and depth habitat of the two varieties.

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Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Ecological controls on the shell geochemistry of pink and white Globigerinoides ruber in the northern Gulf of Mexico: implications for paleoceanographic reconstruction
Series title:
Marine Micropaleontology
DOI:
10.1016/j.marmicro.2011.10.002
Volume
82-83
Year Published:
2012
Language:
English
Publisher:
Elsevier
Contributing office(s):
St. Petersburg Coastal and Marine Science Center
Description:
10 p.
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
Marine Micropaleontology
First page:
28
Last page:
37
Other Geospatial:
Gulf Of Mexico