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Warming in the Arctic could alter predator-prey relationships

In the Arctic, climate change is causing record-setting sea ice decline and earlier and earlier springs.

New research has identified yet another way climate change will impact the Arctic, and its effects could be so wide-reaching that it may even change the food web and the environment of the Tundra.

However, the study found that these changes could also provide a buffer and slow CO2 emissions from thawed permafrost in the Arctic.

Researchers from Washington University in St. Louis studied wolf spiders in the Alaskan Arctic to see how a warming climate might impact the predator-prey relationships of the spiders.

The results were published in the journal Proceedings of the National Academy of Sciences.

The study is one of the few to look at climate change’s impact on habitats and species on a macro level, meaning that the researchers examined not just climate change’s impact on wolf spiders, but the widespread ramifications of those changes.

“We often think about how warmer temperatures might strengthen or weaken interactions between predators and their prey,” said Amanda Koltz, a  postdoctoral researcher in biology in Arts & Sciences who led the research. “But in this case, we show that when warming alters those interactions, it can also lead to changes in ecosystem-level processes like decomposition rates.”

Wolf spiders are one of the most important predators on the Tundra and are one of the most abundant species in the Arctic. The spiders hunt on the ground and will eat almost anything smaller than them, but their preferred food is a small arthropod called springtails.

The springtails, in turn, eat decaying plants and fungus and play an important role in plant matter decomposition rates.

Because wolf spiders eat springtails, they have an indirect effect on decomposition, according to the study.

If decomposition rates change, it could release more harmful greenhouse gases into the atmosphere especially as warming temperatures thaw out frozen permafrost and the trapped CO2 contained within.

Koltz and a team of researchers set up a series of experimental enclosures in Northern Alaska over two summer seasons to test how warming would impact the spider, fungus-eater, and soil system.

The enclosures were kept at different temperatures and at the end of the two seasons, the researchers recorded any changes as well as the number of springtails, mites, spiders and other species.

Interestingly, at the ambient temperatures, high-density populations of wolf spiders left fewer springtails resulting in faster decomposition rates.

In the enclosures that were kept at warmer temperatures, there were still high-density spider populations but higher numbers of springtails and slower decomposition.

The researchers hypothesize that the warmer temperatures changed the spiders’ taste in prey leaving more springtails to do their job in the soil.

“Spiders are not going to save us from climate change, but we found that decomposition is slower under warming when there are more wolf spiders present,” said Koltz. “This suggests that under some circumstances, they could be alleviating some of the effects of warming on carbon losses from the tundra. It’s a good thing.”

By Kay Vandette, Staff Writer

Image Credit: Kiki Contreras

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