RESPONSE OF ARCTIC SURFACE WATER MICROBIAL COMMUNITIES TO SEA ICE CARBOHYDRATE ENRICHMENT
During melt, sea ice releases dissolved and particulate constituents into surface waters, contributing to microbial dynamics and elemental cycling. In this experimental study, we evaluated the response of surface water microbial communities to differential enrichments with dissolved organic matter (DOM) and fractionated exopolymeric substances (EPS) isolated from first year ice. Triplicate time-series experiments, with additions of sea ice DOM and two EPS size fractions were carried out over a period of 9 days in a field laboratory in the Canadian Arctic Archipelago (Resolute, Nunavut) in May 2012. Daily measurements included prokaryote abundance, production (i.e. Leucine incorporation), and DOM and carbohydrate characterization. In all enrichments, prokaryote abundances increased by more than one order of magnitude and bacterial production increased by ca. two orders of magnitude. Prokaryote growth and production remained low in surface waters without sea ice DOM or EPS addition. The surface microbial community responded earlier to the addition of sea ice EPS than DOM, with a lag of 8 days for the latter. Yet, sea ice DOM input triggered the strongest microbial response, with rapid increases in prokaryote abundance, production, and carbohydrate uptake. Our results identify compelling responses of Arctic surface microbial communities to the input of dissolved and gel-like constituents from the sea ice, with wide-ranging implications for carbon cycling in the changing Arctic.
Michel, C., Fisheries and Oceans Canada, Canada, firstname.lastname@example.org
Underwood, G. J., University of Essex, United Kingdom, email@example.com
Meisterhans, G., Fisheries and Oceans Canada, Canada, firstname.lastname@example.org
Niemi, A., Fisheries and Oceans Canada, Canada, email@example.com
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