期刊
ECOLOGICAL APPLICATIONS
卷 19, 期 5, 页码 1365-1375出版社
WILEY
DOI: 10.1890/07-1941.1
关键词
Arctic; change point; choke point; climate change; distribution; Hudson Bay, Canada; killer whale; Orcinus orca; predation; sea ice; subarctic
资金
- ArcticNet, Fisheries and Oceans Canada
- Natural Sciences and Engineering Research Council
- Nunavut Implementation Fund
- Nunavut Wildlife Research Trust Fund
Killer whales (Orcinus orca) are major predators that may reshape marine ecosystems via top-down forcing. Climate change models predict major reductions in sea ice with the subsequent expectation for readjustments of species' distribution and abundance. Here, we measure changes in killer whale distribution in the Hudson Bay region with decreasing sea ice as an example of global readjustments occurring with climate change. We summarize records of killer whales in Hudson Bay, Hudson Strait, and Foxe Basin in the eastern Canadian Arctic and relate them to an historical sea ice data set while accounting for spatial and temporal autocorrelation in the data. We find evidence for choke points,'' where sea ice inhibits killer whale movement, thereby creating restrictions to their Arctic distribution. We hypothesize that a threshold exists in seasonal sea ice concentration within these choke points that results in pulses in advancements in distribution of an ice-avoiding predator. Hudson Strait appears to have been a significant sea ice choke point that opened up approximately 50 years ago allowing for an initial punctuated appearance of killer whales followed by a gradual advancing distribution within the entire Hudson Bay region. Killer whale sightings have increased exponentially and are now reported in the Hudson Bay region every summer. We predict that other choke points will soon open up with continued sea ice melt producing punctuated predator-prey trophic cascades across the Arctic.
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