Twentieth century δ 13 C variability in surface water dissolved inorganic carbon recorded by coralline algae in the northern North Pacific Ocean and the Bering Sea

• Published in: Biogeosciences
• Main Authors: W. Adey, P. Lebednik, S. Hetzinger, R. S. Steneck, U. G. Wortmann, J. Halfar, B. Williams, M. Joachimski
• Format: Article in Journal/Newspaper
• Language: English
• Published: Copernicus Publications 2011
• Subjects: Ecology; QH540-549.5; Life; QH501-531; Geology; QE1-996.5; Bering Sea; Pacific; aleutian low
• Online Access: https://doi.org/10.5194/bg-8-165-2011; https://doaj.org/article/a39afcdff8f04221892c3c109ac970eb

The oxygen isotopic composition and Mg/Ca ratios in the skeletons of long-lived coralline algae record ambient seawater temperature over time. Similarly, the carbon isotopic composition in the skeletons record δ 13 C values of ambient seawater dissolved inorganic carbon. Here, we measured δ 13 C in the coralline alga Clathromorphum nereostratum to test the feasibility of reconstructing the intrusion of anthropogenic CO 2 into the northern North Pacific Ocean and Bering Sea. The δ 13 C was measured in the high Mg-calcite skeleton of three C. nereostratum specimens from two islands 500 km apart in the Aleutian archipelago. In the records spanning 1887 to 2003, the average decadal rate of decline in δ 13 C values increased from 0.03‰ yr −1 in the 1960s to 0.095‰ yr −1 in the 1990s, which was higher than expected due to solely the δ 13 C-Suess effect. Deeper water in this region exhibits higher concentrations of CO 2 and low δ 13 C values. Transport of deeper water into surface water (i.e., upwelling) increases when the Aleutian Low is intensified. We hypothesized that the acceleration of the δ 13 C decline may result from increased upwelling from the 1960s to 1990s, which in turn was driven by increased intensity of the Aleutian Low. Detrended δ 13 C records also varied on 4–7 year and bidecadal timescales supporting an atmospheric teleconnection of tropical climate patterns to the northern North Pacific Ocean and Bering Sea manifested as changes in upwelling.