Antarctic Science

Physical Sciences

High-frequency observations of pH under Antarctic sea ice in the southern Ross Sea

Paul G. Matsona1 c1, Todd R. Martza2 and Gretchen E. Hofmanna1

a1 Department of Ecology, Evolution, and Marine Biology, University of California, Santa Barbara, CA 93106-9620, USA

a2 Scripps Institution of Oceanography, University of California, San Diego, CA 92093, USA

Abstract

Although predictions suggest that ocean acidification will significantly impact polar oceans within 20–30 years, there is limited information regarding present-day pH dynamics of the Southern Ocean. Here, we present novel high-frequency observations of pH collected during spring of 2010 using SeaFET pH sensors at three locations under fast sea ice in the southern Ross Sea. During these deployments in McMurdo Sound, baseline pH ranged between 8.019–8.045, with low to moderate overall variation (0.043–0.114 units) on the scale of hours to days. The variation was predominantly in the direction of increased pH relative to baseline observations. Estimates of aragonite saturation state (ΩAr) were > 1 with no observations of subsaturation. Time series records such as these are significant to the Antarctic science community; this information can be leveraged towards framing more environmentally relevant laboratory experiments aimed at assessing the vulnerability of Antarctic species to ocean acidification. In addition, increased spatial and temporal coverage of pH datasets may reveal ecologically significant patterns. Specifically, whether such variation in natural ocean pH dynamics may drive local adaptation to pH variation or provide refugia for populations of marine calcifiers in a future, acidifying ocean.

(Received March 29 2011)

(Accepted June 18 2011)

(Online publication September 01 2011)

Correspondence:

c1 pmatson@gmail.com

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