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Author (up) Clark, G.F.; Stark, J.S.; Johnston, E.L.; Runcie, J.W.; Goldsworthy, P.M.; Raymond, B.; Riddle, M.J. url  doi
  Title Light-driven tipping points in polar ecosystems Type Journal Article
  Year 2013 Publication Global Change Biology Abbreviated Journal Glob Chang Biol  
  Volume 19 Issue 12 Pages 3749-3761  
  Keywords Ecology; benthic; biodiversity; irradiance; macroalgae; marine ecology; polar; regime shift  
  Abstract Some ecosystems can undergo abrupt transformation in response to relatively small environmental change. Identifying imminent 'tipping points' is crucial for biodiversity conservation, particularly in the face of climate change. Here, we describe a tipping point mechanism likely to induce widespread regime shifts in polar ecosystems. Seasonal snow and ice-cover periodically block sunlight reaching polar ecosystems, but the effect of this on annual light depends critically on the timing of cover within the annual solar cycle. At high latitudes, sunlight is strongly seasonal, and ice-free days around the summer solstice receive orders of magnitude more light than those in winter. Early melt that brings the date of ice-loss closer to midsummer will cause an exponential increase in the amount of sunlight reaching some ecosystems per year. This is likely to drive ecological tipping points in which primary producers (plants and algae) flourish and out-compete dark-adapted communities. We demonstrate this principle on Antarctic shallow seabed ecosystems, which our data suggest are sensitive to small changes in the timing of sea-ice loss. Algae respond to light thresholds that are easily exceeded by a slight reduction in sea-ice duration. Earlier sea-ice loss is likely to cause extensive regime shifts in which endemic shallow-water invertebrate communities are replaced by algae, reducing coastal biodiversity and fundamentally changing ecosystem functioning. Modeling shows that recent changes in ice and snow cover have already transformed annual light budgets in large areas of the Arctic and Antarctic, and both aquatic and terrestrial ecosystems are likely to experience further significant change in light. The interaction between ice-loss and solar irradiance renders polar ecosystems acutely vulnerable to abrupt ecosystem change, as light-driven tipping points are readily breached by relatively slight shifts in the timing of snow and ice-loss.  
  Address School of Biological, Earth and Environmental Science, University of New South Wales, Sydney, NSW, 2052, Australia  
  Corporate Author Thesis  
  Publisher Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 1354-1013 ISBN Medium  
  Area Expedition Conference  
  Notes PMID:23893603 Approved no  
  Call Number LoNNe @ kagoburian @ Serial 850  
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