| 英文摘要: | Climate-driven demographic changes could cause drastic decline in the global emperor penguin population, driving some colonies to extinction. Few species depend on sea ice to the extent that emperor penguins do. Recent climate change, especially warming in the Antarctic, has substantially reduced seasonal sea ice concentration and duration, and these patterns are predicted to continue1, 2. What might this mean for emperor penguins? In a study published in Nature Climate Change, Stéphanie Jenouvrier and colleagues3 show that the global emperor penguin population will decline drastically, and many colonies will face substantial risk of extinction by 2100. Standing over 1.2 m tall and weighing up to 45 kg, emperor penguins are the largest of all extant penguin species. The stars of film and documentary alike, they are visually appealing and biologically fascinating; they are adapted to the extreme Antarctic environment and are the only species of penguin with the habit of breeding in the middle of winter. Many important aspects of their life cycle depend on sea ice1, 2, 4. Penguins depend on fixed sea ice (fast ice) for successful reproduction and gather at traditional breeding sites (colonies) during March–April when sea ice is thickening. They need just the right amount of sea ice at just the right time. Too little sea ice will constrain the availability of breeding sites, reduce prey availability and can also make penguins vulnerable to predation. Too much sea ice means longer foraging trips for parents, lower feeding rates for chicks, and consequently, lower adult survival and reproductive success. Higher air or sea surface temperatures and early breakup of sea ice will reduce survival, and multiple years of poor sea ice will cause population declines and eventually local extinction2, 5. Using long-term demographic information from the Terre Adélie penguin population, sea ice concentration data, and sophisticated, multi-pronged modelling techniques, Jenouvrier et al.3 investigate what the future might hold for these obligate sea ice breeders. First, they linked seasonal sea ice concentration anomalies (SICa; deviations from long-term seasonal averages) to survival and reproduction of penguins by modelling these parameters as functions of SICa for four biologically relevant seasons in the penguin life cycle. Based on these estimates, they developed a two-sex, seasonal, climate-driven population model. Next they employed an ensemble of ten IPCC climate models to forecast sea ice concentration, which allowed the determination of SICa. Finally, they fed the projected SICa data to the demographic model, which was subsequently used for population projections and viability analyses. Their results indicate that the Terre Adélie population of emperor penguins will decline from around 6,000 to only 400 breeding pairs by 2100, and that the population will face a high risk of quasi-extinction (a reduction to less than 10% of its current size). These conclusions are not new4, 7. But the present study is innovative and exciting because of the steps Jenouvrier et al.3 took to expand the Terre Adélie population study to make a species-level threat assessment. There are 45 currently known colonies of emperor penguins. The authors argue that most of these colonies have never been visited by humans, and it is highly improbable that they will ever be the focus of long-term demographic studies. How does one go about making species-level inferences when detailed data are only available for one out of 45 colonies? Emperor penguins depend on sea ice for breeding, brood rearing and feeding. We also know that climate change will undoubtedly affect the sea ice environment in and around all emperor penguin colonies. If one can determine current sea ice concentration, quantify how climate change will influence the sea ice environment and determine how the altered sea ice environment will influence penguin demography at each colony, it should be possible to make species-level inferences regarding the dynamics and persistence of emperor penguin populations under climate change. Using these precise steps, Jenouvrier et al.3 show that the global population of emperor penguins will probably decline substantially and that 20% of the penguin colonies could go functionally extinct by 2100. The colonies located at northerly latitudes face a greater risk of drastic population declines or demise compared with colonies located poleward. These projections are alarming but are they alarmist? The evidence suggests not. All available data show evidence for substantial warming in Antarctica1, 2, 9, and general circulation models (GCMs) under most scenarios predict further decline and greater variability in sea ice concentration1, 4. In fact, the recent extinction of an Emperor Island colony of emperor penguins has been directly linked to decline in seasonal sea ice concentration and duration attributable to warming temperatures2.
Jenouvrier/ WHOI
Emperor penguins raising their offspring on sea ice.
- Ainley, D. et al. Ecol. Monographs 80, 49–66 (2010).
- Trathan, P. N., Fretwell, P. T. & Stonehouse, B. PLoS ONE 6, e14738 (2011).
- Jenouvrier, S. et al. Nature Clim. Change 4, 715–718 (2014).
- Jenouvrier, S. et al. Glob. Change Biol. 18, 2756–2770 (2012).
- Fretwell, P. T. PLoS ONE 9, e85285 (2014).
- Barbroud, C. & Weimerskirch, H. Nature 411, 183–186 (2001).
- Jenouvrier, S. et al. Proc. Natl Acad. Sci. USA 106, 1844–1847 (2009).
- Hunter, C. M. et al. Ecology 91, 2883–2897 (2010).
- Thomas, E. R., Dennis, P. F., Bracegirdle, T. J. & Franzke, C. Geophys. Res. Lett. 36, L20704 (2009).
- Cahill, A. E. et al. Proc. R. Soc. B 280, 20121890 (2013).
- Moritz, C. & Agudo, R. Science 341, 504–508 (2013).
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Affiliations
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Madan K. Oli is in the Department of Wildlife Ecology and Conservation, University of Florida, Gainesville, Florida 32611, USA and at the Institute of Evolutionary Biology and Environmental Studies, University of Zürich, Winterthurerstrasse 190, CH-8057 Zürich, Switzerland
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