Arctic Species at the Cliff’s Edge

January 25, 2014 — Leave a comment

New paper models changes for Arctic species due to climate change.

Climate change will affect species in the Arctic in ways that will produce ripple effects around the world. Olivier Gilg, BenoÎt Sittler, and Ilkka Hanski, writing in the journal Global Change Biology, warn that rapid arctic heating, already pushing species like the polar bear closer to extinction, will also interfere with the breeding habits of the collard lemming. The seemingly small change could have disastrous consequences for a number of species that feed on the lemmings, such as snowy owls, Arctic foxes, the long-tailed skua (a seagull-like bird) and the stoat (also known as the short-tailed weasel), all of which could have further effects on other animals later this century.

“Small changes for lemmings can indeed induce huge changes at the community level, because lemmings are almost the only prey for the predators in the high Arctic. So if lemmings decline and stop cycling, their predators will either disappear or focus on alternate prey (if any), and in turn the latter will also decline,” Gilg told THE FUTURIST.

In their report, Gilg, Sittler, and Hanski present a number of scenarios showing how temperature and snowfall changes will affect lemming behavior. Among the most important factors in their study are the growing likelihood of longer arctic summers and a poor quality snow layer during winter. Lemmings typically dig deep snow tunnels and breed in the winter snow so that their offspring can emerge in the spring with several months to feed on freshly thawed vegetation. The sudden arrival of lots of lemmings in the spring (sometimes referred to as “lemming peaks”) provides food for the Arctic foxes, owls, and skua. Only the wily weasel (stoat) can burrow into the lemmings’ dens to hunt them during the region’s colder months.

A longer summer would seem to be good for the lemmings, as this would increase the time available for the younger members of the species to forage and grow before the onset of harsher conditions. But the shorter winter season means less time for breeding. The result is far fewer lemmings in the spring for the predator species to feed on. The change in lemming breeding habits will likely alter the predators’ habits as well, the researchers conclude. All of these disruptions will add to pressure that the animals already face from encroaching populations of other alien species attracted to the north’s rapidly rising temperatures, like the red fox and seagulls.

The researchers’ scenarios show that the change in the lemming population is likely to reduce skuas’ breeding at both of the two Greenland areas the researchers modeled for (two completely uninhabited areas of one million square kilometers). In one scenario, the snowy owl disappeared from at least one of the areas and experienced much lower breeding in the second. The breeding success of the Arctic fox was reduced by a factor of two, and the stoat population decreased significantly in one location and went extinct in another.

“Our results underscore the fragility of the dynamic interactions between the lemmings and their predators, because the life-time reproductive success of the predators is much dependent on the years of high lemming density. Even a moderate advance in snow melt has a potentially great impact on the community, and it may ultimately cause the local extinction of some of the predator species,” the authors write. “The lemmings themselves do not commit suicide as foreseen for centuries, but their spectacular high-amplitude cyclic dynamics might as well be ‘thrown off the cliff’ by climate change.”

Many researchers argue that the rapid climatic and biota changes playing out in the Arctic provide a window to how temperatures and animal behaviors will shift as a result of climate change. The Arctic is warming about twice as fast as the rest of the planet. By the end of this century, the globe is forecast to warm anywhere from 4°C to 7°; the Arctic is forecast to heat up 6° to 9°. As previously reported in THE FUTURIST, oceanographers have forecast that the Arctic Ocean could experience iceless summers by 2040, and one model holds that the Arctic could be ice-free during the summer months in just 11 years.

The Arctic also provides a relatively ideal setting for the analysis of weather patterns on animals, as it hosts the earth’s simplest vertebrate community. There are few species that can survive in the harsh terrain, and their interactions tend to be more direct and more observable. Importantly, the changes in the breeding and survival patterns of arctic species will have less-predictable effects for other animals as well.

“The dynamics of this community influence the dynamics of other terrestrial vertebrates through indirect effects and across several trophic levels, hence the dynamics of this community have important consequences for the structure and functioning of the Arctic biota,” the researchers note.

“Changes are now occurring so rapidly and impact the ecosystems so strongly that species and even communities will not be able to cope and to adjust,” said Gilg. “Many arctic species will likely disappear within just years or decades, and what happens in the Arctic should be regarded as a summary of what will happen next in countries with more temperate climates.”

– Patrick Tucker

 

Source: “Climate Change and Cyclic Predator-Prey Population Dynamics in the High Arctic” by Olivier Gilg, BenoÎt Sittler, and Ilkka Hanski, Global Change Biology (2009). Personal interview.

 

Originally published in THE FUTURIST, January-February 2010

 

 

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