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Abstract

Ocean acidification substantially alters ocean carbon chemistry and hence pH but the effects on sea ice formation and the
CO2 concentration in the enclosed brine channels are unknown. Microbial communities inhabiting sea ice ecosystems
currently contribute 10–50% of the annual primary production of polar seas, supporting overwintering zooplankton species,
especially Antarctic krill, and seeding spring phytoplankton blooms. Ocean acidification is occurring in all surface waters but
the strongest effects will be experienced in polar ecosystems with significant effects on all trophic levels. Brine algae
collected from McMurdo Sound (Antarctica) sea ice was incubated in situ under various carbonate chemistry conditions. The
carbon chemistry was manipulated with acid, bicarbonate and bases to produce a pCO2 and pH range from 238 to
6066 matm and 7.19 to 8.66, respectively. Elevated pCO2 positively affected the growth rate of the brine algal community,
dominated by the unique ice dinoflagellate, Polarella glacialis. Growth rates were significantly reduced when pH dropped
below 7.6. However, when the pH was held constant and the pCO2 increased, growth rates of the brine algae increased by
more than 20% and showed no decline at pCO2 values more than five times current ambient levels. We suggest that
projected increases in seawater pCO2, associated with OA, will not adversely impact brine algal communities.

Item Type:	Article
Authors/Creators:	McMinn, A and Muller, M and Martin, A and Ryan, KG
Journal or Publication Title:	PLOS One
ISSN:	1932-6203
DOI / ID Number:	10.1371/journal.pone.0086984
Additional Information:	Creative Commons Attribution 4.0 International Licence(CC BY 4.0)
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