July 15, 2011

Arctic Species Prefer Warmer Climate?

Filed under: Adaptation, Animals

Let us imagine someone who suddenly gets interested in climate change and the Arctic. They conduct an internet search on “Climate Change and Arctic” and over 11,000,000 sites are identified. If a person spent one minute looking at each site, it would take them 20 years to visit every site. Of course, over the next 20 years, millions of sites will undoubtedly be added – no person could ever get to the end of these sites proclaiming that the Arctic is ground zero for climate change, the ice is melting, permafrost is being destroyed, habitats of everything and anything living there are highly sensitive to even the smallest change in climate, the whole place is fragile beyond belief, and on and on.

Several articles have appeared recently in leading journals with news that fails to get coverage in the millions of sites assuring us that our actions are destroying pristine Arctic regions.

The first article was generated by six scientists from leading institutions in the United Kingdom, Australia, Denmark, France, and South Africa; the White et al. team received funding from agencies in these various countries to conduct the research.

The team turned their attention to the Great Cormorants of Greenland; these are large black birds found throughout the Arctic. The birds live mainly on coasts nesting on cliffs or in trees, and they can dive to considerable depths to catch fish and eels Because of their amazing fishing skills, many were hunted to near extinction by fisherman, but thanks to conservation efforts, their numbers have increased in recent decades. In northern Norway, Great Cormorants are traditionally seen as semi-sacred with locals who believe it is good luck to have Great Cormorants gather near their village or settlement.


Great Cormorants enjoying warmer temperatures?

White et al. begin their article noting that “During recent decades, the Arctic has warmed and sea ice has retreated. While this has resulted in range contraction and negative population trends in some Arctic species, climate change is a potential boon for others.”

Given this suggestion that climate change could be beneficial to some species in the Arctic, we knew this could get good.

White et al. continue stating “For example, the recent warming of the Arctic may be associated with increasing populations and a northerly expansion of Great Cormorants Phalacrocorax carbo, which are now breeding north of the Arctic Circle in Greenland. While a reduction of hunting pressure is likely to have contributed to this population trend, it is possible that the trend is enhanced as a direct effect of increasing temperatures or an indirect effect of temperature on the distribution of prey.”

The authors note that data for the number of breeding pairs present in 67 Cormorant colonies in the Disko Bay, Greenland and adjacent areas are available from surveys taken intermittently between 1946 and 2005. They also gathered sea surface temperatures (SSTs) over the same time period. You guessed it as they report “Rates of population change of Great Cormorant colonies near Disko Bay, West Greenland, were positively correlated with winter SST. On average, populations increased during relatively warm years and decreased during relatively cold years and the highest rates of population change correspond with periods of relatively high SST in recent years and during the 1960s. This suggests that the abundance of Cormorants in this region is likely to increase as the climate warms.” They conclude “Taken together, the positive relationship between rates of population change in Cormorants and SST, the likely positive impact of Arctic warming on the preferred prey species of Cormorants, and the flexible food preferences and foraging strategies of Cormorants suggest that Cormorants are likely to benefit from a warming Arctic.” Enough said.

Our next article appeared recently in the Canadian Journal of Zoology dealing with higher air temperatures and responses of moose. The three authors are all from agencies in Canada; Lowe et al. reveal that “Funding for this project was provided by the Natural Sciences and Engineering Research Council of Canada, Ontario Ministry of Natural Resources, Trent University, and Ontario Federation of Anglers and Hunters.”

The story with moose is similar to the story we hear for so many other species. Lowe et al. review the extensive literature on climate change and the response of moose, and generally others have found that moose may experience stress with higher temperatures. Others have found “moose heat stress thresholds of 14ºC in summer and -5 ºC in winter with increased respiration rates, and open mouth panting at 20ºC in summer and 0 ºC in winter.” Based on findings of others, Lowe et al. expected to observe any number of responses of the moose to higher winter and summer temperatures.

Well, it didn’t happen! Lowe et al. conclude “Our results did not fully concur with these findings, as we failed to detect a clear relationship between habitat use and high temperatures in our study area in summer or winter at the thresholds that we tested.”


A warmer and happier moose?

Furthermore, they conclude “We also failed to detect consistent differences in distances of movement by moose in response to temperature. If moose employed behavioral adaptations to cope with unfavorable temperatures, then we should have observed decreased daily movement during periods of heat stress and increased nocturnal behavior when temperatures became extreme during the day. Yet, the relationship between temperature and movement was weak throughout the day in both seasons.”

Both of these studies show us while so many warn of impending doom for ecosystems in high latitudes as climate changes, empirical evidence for many species may indicate substantial benefits for a warmer world. As we see in these articles, Great Cormorants and moose seem fine with the idea of warmer summer and winter conditions in high latitude regions!

References:

Lowe, S.J., B.R. Patterson, and J.A. Schaefer. 2010. Lack of behavioral responses of moose (Alces alces) to high ambient temperatures near the southern periphery of their range. Canadian Journal of Zoology, 88, 1032-1041.

White, C.R., D. Boertmann, D. Grémillet, P.J. Butler, J.A. Green, and G.R. Martin. 2010. The relationship between sea surface temperature and population change of Great Cormorants Phalacrocorax carbo breeding near Disko Bay, Greenland. Ibis: The International Journal of Avian Science, 153, 170-174.




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