Response of sea-ice microbial communities to environmental d

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TitleResponse of sea-ice microbial communities to environmental disturbance: An in situ transplant experiment in the AntarcticAbstractSea-ice microbial communities are integral to primary and secondary production in icecovered regions of the Southern Ocean, but few studies have characterised the heterogeneity of microbes within the ice or determined whether habitat variability influences community dynamics. We examined the response of sea-ice microbes to key physicochemical variables by conducting an 18 d reciprocal transplant experiment within Antarctic fast-ice. A series of ice cores were extracted from 2.6 m annual ice and reinserted upside down to expose resident microbial assemblages to significantly different light, temperature and salinity regimes. The abundance and community composition of bacteria, microalgae and protozoa was subsequently determined within 3 sections of each core (top, middle and bottom) and compared with experimental controls. Results demonstrate that iceassociated microbes are finely attuned to discrete microhabitats within the sea-ice matrix. Positive growth and a shift in community composition was observed for microalgae moved from the top to the bottom of the ice, but significant bleaching of photosynthetic pigments resulted in zero net growth for bottom-ice communities exposed to the surface. Although bacteria may have been less vulnerable to initial change in their microenvironment, there was no significant increase in the average abundance of cells at either end of the flipped cores after 18 d, despite a presumed increase in algal-derived dissolved organic matter. This suggests a significant lag in the response time of bacteria to available growth substrates and a temporary mÌalfunction Ìof the microbial loop. © Inter-Research 2011.AcknowledgementsWe acknowledge the logistical support of Antarctica New Zealand and, in particular, S. Gordon, Project Manager of the Latitudinal Gradient Project. A.M. was supported by a Victoria University of Wellington Postgraduate Scholarship for PhD Study and also thanks the Trans Antarctic Association for support in funding this research, K. M. Hare for graphic design and M. Kennedy for advice on phylogenetics. K.G.R. acknowledges the support of the Foundation of Research, Science & Technology (contract no. VICX0706).

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1st AuthorMartin, A.AuthorMartin, A.Anderson, M.Thorn, C.Davy, S.Ryan, K.Year2011JournalMarine Ecology Progress SeriesVolume424Pages25-37DOI10.3354/meps08977URLhttps://www.scopus.com/inward/recor.....c9de23da3d52b99e641df8fa5Keywordsbacteriumdissolved organic matterelectrokinesisenvironmental disturbanceice covermicroalgamicrobial communitymicrobial loopphotosynthesisphysicochemical propertyprimary productionprotozoansea icesea surface salinitysea surface temperaturesecondary production, Southern Ocean, algaeBacteria (microorganisms)Protozoa, rank5Author KeywordsAntarcticaDGGEMicrobesMicrobial loopSea-iceTransplant experiment

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TypeArticleCitationMartin, A., Anderson, M., Thorn, C., Davy, S. and Ryan, K. (2011). Response of sea-ice microbial communities to environmental disturbance: An in situ transplant experiment in the Antarctic. Marine Ecology Progress Series, 424: 25-37 doi:10.3354/meps08977 IdentifierMartin2011Relevancerank5