The reconstruction of deep-sea bottom water temperature (BWT) is important to assess the ocean’s response to and role in orbital- and millennial-scale climate change. Deep-sea paleothermometry employs magnesium to calcium (Mg/Ca) ratios in calcitic benthic microfaunas (foraminifera, ostracodes) as a primary proxy method. Mg/Ca paleothermometry may, however, be complicated by bottom water carbonate ion chemistry, which might affect Mg/Ca ratios in shells. To address temperature and carbonate ion influence on Mg/Ca ratios, we studied Mg/Ca ratios in the benthic ostracode genus Krithe in the North Atlantic and Arctic oceans using a 686-specimen core top collection, including 412 previously unpublished analyses. Mg/Ca ratios are positively correlated to temperature in multiple species from the North Atlantic [BWT = (0.885 × Mg/Ca) − 5.69, r2 = 0.73] and for K. glacialis in the Arctic Ocean and Nordic Seas [BWT = (0.439 × Mg/Ca) − 5.14, r2 = 0.50], consistent with previously published calibrations. We found no evidence for a relationship between Krithe Mg/Ca and carbonate ion saturation in the North Atlantic Ocean, Nordic Seas, and Arctic Ocean, supporting the use of Krithe Mg/Ca for reconstructing past BWT.
Archive for June 25th, 2012
Ostracode Mg/Ca paleothermometry in the North Atlantic and Arctic oceans: evaluation of a carbonate ion effectPublished 25 June 2012 Science Leave a Comment
In another apparent casualty of carbon emissions, a local oyster grower has opened a hatchery in Hawaii, finding the waters there more hospitable to fragile baby oysters than Willapa Bay.
Position and Grade: Research Scientist (P-3)
Organizational Unit: Radioecology Laboratory
IAEA Marine Environment Laboratories (IAEA-MEL), Monaco
Department of Nuclear Sciences and Applications
Duty Station: Monaco
Issue Date: 19 June 2012
Application Deadline: 31 July 2012
Type/Duration of Appointment: Fixed term, 3 years (subject to a probationary period of 1 year)