Planktonic foraminiferal shell weight as a proxy for changing carbonate ion concentration in the Cariaco Basin, Venezuela
Abstract
Ocean acidification, due to increased atmospheric CO2, has diverse implications for marine calcifiers. In this study we use biweekly sediment trap samples and concurrent hydrographic measurements collected between January 2003 and May 2007 in the Cariaco Basin, Venezuela (10°30’ N, 65°31 W) to assess the relationship between shell weight and carbonate ion concentration [CO32-] of two planktonic foraminiferal species, Globigerinoides ruber and Orbulina universa.. Measured salinity, pH, sea surface temperature (SST) and total alkalinity (TA) were used to estimate pCO2 and [CO32-]. Shells of both G. ruber (300-355 µm) and O. universa (425 - 700 µm) species were picked (10-20 per sample) and weighed. Globigerinoides ruber shell weights varied from 7 µg to 19 µg from 2003 to 2007, with an average value of 11 ± 0.86 µg while surface water [CO32-] ranged from ~225-290 µmol/kg and averaged 250 µmol/kg. The data reveal a strong positive linear relationship between foraminiferal shell weight and [CO32-] for G. ruber and we expect to observe a similar relationship for O. universa. The initial results suggest the use of foraminiferal shell weight as a proxy for past changes in ocean pH.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2010
- Bibcode:
- 2010AGUFMPP11C1453M
- Keywords:
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- 1630 GLOBAL CHANGE / Impacts of global change;
- 1635 GLOBAL CHANGE / Oceans