TY - JOUR
T1 - Globigerinoides ruber morphotypes in the Gulf of Mexico
T2 - A test of null hypothesis
AU - Thirumalai, Kaustubh
AU - Richey, Julie N.
AU - Quinn, Terrence M.
AU - Poore, Richard Z.
N1 - Funding Information:
We thank the crew of the R/V Pelican for assisting us in the collection and redeployment of the sediment trap, and the crew of the R/V Cape Hatteras for aid in obtaining the cores utilized in this study. We acknowledge Caitlin Reynolds for aiding sample preparation and Jennifer Flannery for help with the SEM images. The authors are thankful to Judson Partin for helpful discussion and for critiquing a preliminary draft of this manuscript along with Deb Willard. K. T. thanks the UTIG Ewing-Worzel fellowship for support. This research was funded by the U.S. Geological Survey Climate and Land Use Research & Development program and the National Science Foundation (OCE-0902921). This is UTIG Contribution #2719.
PY - 2014/8/11
Y1 - 2014/8/11
N2 - Planktic foraminifer Globigerinoides ruber (G. ruber), due to its abundance and ubiquity in the tropical/subtropical mixed layer, has been the workhorse of paleoceanographic studies investigating past sea-surface conditions on a range of timescales. Recent geochemical work on the two principal white G. ruber (W) morphotypes, sensu stricto (ss) and sensu lato (sl), has hypothesized differences in seasonal preferences or calcification depths, implying that reconstructions using a non-selective mixture of morphotypes could potentially be biased. Here, we test these hypotheses by performing stable isotope and abundance measurements on the two morphotypes in sediment trap, core-top, and downcore samples from the northern Gulf of Mexico. As a test of null hypothesis, we perform the same analyses on couplets of G. ruber (W) specimens with attributes intermediate to the holotypic ss and sl morphologies. We find no systematic or significant offsets in coeval ss-sl δ18O, and δ́13C. These offsets are no larger than those in the intermediate pairs. Coupling our results with foraminiferal statistical model INFAUNAL, we find that contrary to previous work elsewhere, there is no evidence for discrepancies in ss-sl calcifying depth habitat or seasonality in the Gulf of Mexico.
AB - Planktic foraminifer Globigerinoides ruber (G. ruber), due to its abundance and ubiquity in the tropical/subtropical mixed layer, has been the workhorse of paleoceanographic studies investigating past sea-surface conditions on a range of timescales. Recent geochemical work on the two principal white G. ruber (W) morphotypes, sensu stricto (ss) and sensu lato (sl), has hypothesized differences in seasonal preferences or calcification depths, implying that reconstructions using a non-selective mixture of morphotypes could potentially be biased. Here, we test these hypotheses by performing stable isotope and abundance measurements on the two morphotypes in sediment trap, core-top, and downcore samples from the northern Gulf of Mexico. As a test of null hypothesis, we perform the same analyses on couplets of G. ruber (W) specimens with attributes intermediate to the holotypic ss and sl morphologies. We find no systematic or significant offsets in coeval ss-sl δ18O, and δ́13C. These offsets are no larger than those in the intermediate pairs. Coupling our results with foraminiferal statistical model INFAUNAL, we find that contrary to previous work elsewhere, there is no evidence for discrepancies in ss-sl calcifying depth habitat or seasonality in the Gulf of Mexico.
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U2 - 10.1038/srep06018
DO - 10.1038/srep06018
M3 - Article
C2 - 25109442
AN - SCOPUS:84905920580
SN - 2045-2322
VL - 4
JO - Scientific reports
JF - Scientific reports
M1 - 6018
ER -