Decadal timescale variability in ecosystem properties in the

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TitleDecadal timescale variability in ecosystem properties in the ponds of the McMurdo Ice Shelf, southern Victoria Land, AntarcticaAbstractMeltwater ponds are important biodiversity elements in continental Antarctica. Many occupy closed basins and are vulnerable to changes in the balance between water accrual, through melting of ice and snow, and water loss by ablation and evaporation. We use a two-decade long record of ponds on the McMurdo Ice Shelf to assess temporal variability in key limnological variables. Ponds underwent many-fold change in biologically conservative variables, such as conductivity, and changes were similar in ponds from different catchments but of comparable area. In contrast, biologically active variables (pH, inorganic nutrients and planktonic/benthic biomass) are buffered by in-pond processes and show consistency between years and no coherence across catchments. Coherent behaviour across catchments implies an overarching, climatic effect. However, we could identify no signature of summer air temperature or irradiance in pond dynamics, although winter snow deposition may leave a legacy of low conductivity to the following summer. While ponds are clearly affected by climate, our data show that ecosystem responses are complex and highlight the need for system-appropriate, long-term observation if directional environmental change is to be separated from inherent variability in systems that respond to multiple climatic variables and which have significant biological buffering capacity. Copyright Antarctic Science Ltd 2013.AcknowledgementsThis research was conducted over a long period and was dependent on field contributions from a wide range of people. In large part it was funded by the New Zealand Foundation for Research, Science and Technology through contracts CO1X0220, CO1605 and CO1X0306. We would like to acknowledge the ongoing logistic support of Antarctica New Zealand, the National Institute of Water and Atmospheric Research (NIWA) and the University of Canterbury and to thank all participants of the K081 event over many years of research. The manuscript was improved by the suggestions of the editor, one of the fathers of Antarctic limnology, Dr En Kaup, and an anonymous reviewer

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1st AuthorHawes, I.AuthorHawes, I.Howard-Williams, C.Sorrell, B.Year2014JournalAntarctic ScienceVolume26Number3Pages219-230DOI10.1017/S0954102013000576URLhttps://www.scopus.com/inward/recor.....12f877f0a382ff0c816ddf311Keywordsbiomasscatchmentchlorophyll aclimate conditionsdecadal variationecosystem dynamicsecosystem responseelectrical conductivitylimnologymeltwaternutrient dynamicspHpondclimate effectice shelf, AntarcticaEast AntarcticaMcMurdo Ice Shelf, rank5Author KeywordsChlorophyll aconductivitynutrientspHpond ecosystemstemporal change

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TypeArticleCitationHawes, I., Howard-Williams, C. and Sorrell, B. (2014). Decadal timescale variability in ecosystem properties in the ponds of the McMurdo Ice Shelf, southern Victoria Land, Antarctica. Antarctic Science, 26(3): 219-230 IdentifierHawes2014bRelevancerank5

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Hawes, I.