Century-scale trends and seasonality in pH and temperature for shallow zones of the Bering Sea

Fietzke, Jan, Ragazzola, Federica, Halfar, Jochen, Dietze, Heiner, Foster, Laura C., Hansteen, Thor H., Eisenhauer, Anton and Steneck, Robert S. (2015) Century-scale trends and seasonality in pH and temperature for shallow zones of the Bering Sea Proceedings of the National Academy of Sciences of the United States of America (PNAS), 112 (10). pp. 2960-2965. DOI 10.1073/pnas.1419216112.

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Abstract

No records exist to evaluate long-term pH dynamics in high-latitude oceans, which have the greatest probability of rapid acidification from anthropogenic CO2 emissions. We reconstructed both seasonal variability and anthropogenic change in seawater pH and temperature by using laser ablation high-resolution 2D images of stable boron isotopes (δ11B) on a long-lived coralline alga that grew continuously through the 20th century. Analyses focused on four multiannual growth segments. We show a long-term decline of 0.08 ± 0.01 pH units between the end of the 19th and 20th century, which is consistent with atmospheric CO2 records. Additionally, a strong seasonal cycle (∼0.22 pH units) is observed and interpreted as episodic annual pH increases caused by the consumption of CO2 during strong algal (kelp) growth in spring and summer. The rate of acidification intensifies from –0.006 ± 0.007 pH units per decade (between 1920s and 1960s) to –0.019 ± 0.009 pH units per decade (between 1960s and 1990s), and the episodic pH increases show a continuous shift to earlier times of the year throughout the centennial record. This is indicative of ecosystem shifts in shallow water algal productivity in this high-latitude habitat resulting from warming and acidification.

Document Type: Article
Additional Information: WOS:000350646500031
Keywords: ocean acidification, boron isotopes, isotope imaging, laser ablation ICP–MS, crustose algae
Research affiliation: OceanRep > GEOMAR > FB2 Marine Biogeochemistry > FB2-BM Biogeochemical Modeling
OceanRep > GEOMAR > FB2 Marine Biogeochemistry > FB2-MG Marine Geosystems
Kiel University
OceanRep > GEOMAR > FB4 Dynamics of the Ocean Floor > FB4-MUHS Magmatic and Hydrothermal Systems
Refereed: Yes
Open Access Journal?: No
DOI etc.: 10.1073/pnas.1419216112
ISSN: 0027-8424
Related URLs:
Projects: BIOACID
Date Deposited: 03 Mar 2015 10:24
Last Modified: 13 Apr 2017 08:05
URI: http://oceanrep.geomar.de/id/eprint/27768

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