Effects of CO2 concentration on a late summer surface sea ic

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TitleEffects of CO2 concentration on a late summer surface sea ice communityAbstractAnnual fast ice at Scott Base (Antarctica) in late summer contained a high biomass surface community of mixed phytoflagellates, dominated by the dinoflagellate, Polarella glacialis. At this time of the year, ice temperatures rise close to melting point and salinities drop to less than 20. At the same time, pH levels can rise above 9 and nutrients can become limiting. In January 2014, the sea ice microbial community from the top 30 cm of the ice was exposed to a gradient of pH and CO2 (5 treatments) that ranged from 8.87 to 7.12 and 5-215 µmol CO2 kg−1, respectively, and incubated in situ. While growth rates were reduced at the highest and lowest pH, the differences were not significant. Likewise, there were no significant differences in maximum quantum yield of PSII (Fv/Fm) or relative maximum electron transfer rates (rETRmax) among treatments. In a parallel experiment, a CO2 gradient of 26–230 µmol CO2 kg−1(5 treatments) was tested, keeping pH constant. In this experiment, growth rates increased by approximately 40 percent with increasing CO2, although differences among treatments were not significant. As in the previous experiment, there was no significant response in Fv/Fm or rETRmax. A synchronous grazing dilution experiment found grazing rates to be inconclusive These results suggest that the summer sea ice brine communities were not limited by in situ CO2 concentrations and were not adversely affected by pH values down to 7.1. 2017, Springer-Verlag Berlin Heidelberg.AcknowledgementsWe wish to acknowledge fnancial support from Australian Antarctic Science Grants (AAS 4319) and Victoria University of Wellington Grant 100241. We would also like to thank Antarctica New Zealand for logistical support at Scott Base.Funding Details100241, Faculty of Science, VUW, Faculty of Science, Victoria University of Wellington; 4319, AAD, Australian Antarctic Division

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1st AuthorMcMinn, A.AuthorMcMinn, A.Müller, M.Martin, A.Ugalde, S.Lee, S.Castrisios, K.Ryan, K.Year2017JournalMarine BiologyVolume164Number4DOI10.1007/s00227-017-3102-4URLhttps://www.scopus.com/inward/recor.....a426c8f22bb9b03c6e5b505a3KeywordsalgaeDinophyceaePhytomastigophoreaPolarella glacialis, rank5Author KeywordsAntarcticaBrineCO2pHSea ice algaeSummer

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TypeArticleCitationMcMinn, A., Müller, M., Martin, A., Ugalde, S., Lee, S., Castrisios, K. and Ryan, K. (2017). Effects of CO2 concentration on a late summer surface sea ice community. Marine Biology, 164(4) IdentifierMcMinn2017Relevancerank5Antarctica NZ supported?YesNZARI?No