Arctic Biodiversity Trends 2010

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Ecosystems

Arctic Biodiversity Trends 2010

#15 INDICATOR Effects of decreased freshwater ice cover

duration on biodiversity

T.D. Prowse , Water and Climate Impacts Research Centre, University of Victoria, British Columbia, Canada. K. Brown , Water and Climate Impacts Research Centre, University of Victoria, British Columbia, Canada.

Lapland Lars Lindholm/iStockphoto

Ice cover is an important component of northern freshwater ecosystems influencing numerous physical, chemical, and biological processes in standing-water (lentic) and running-water (lotic) systems [1]. The duration of Arctic lake and river ice is determined by the dates of autumn freeze-up and spring break-up, the timing of which is strongly controlled by climate [e.g., 2, 3]. The broad extent of lakes and rivers throughout the northern high-latitudes provides good spatial coverage necessary to make the timing of lake and river ice freeze-up and break- up an effective indicator of climate change, and how such change might be affecting these important aquatic ecosystems.

Population/ecosystem status and trends

Records of lake and river ice duration are available for the Arctic from a variety of sources covering different time periods, from remote sensing and direct ice-observing programs to historical archives and sediment cores. Changes in the taxa buried in lake and pond sediments have been used by many researchers to identify warming trends and the historical presence/absence of ice cover on northern lakes [e.g., 4–9]. In general, such evidence

points towards warming temperatures and shorter ice durations since the end of the Little Ice Age around 1850, with greater changes observed in northernmost areas when compared to more temperate locations [8]. Ground- based observation and remote sensing are being used to quantify shorter-term trends. These studies are revealing a number of key temporal trends in Arctic lake and river ice cover.