Experts investigate ambiguous amphibian future

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New information warns of increasing survival pressures on amphibian life in the Pacific Northwest as a result of climate change and non-native fish.

SFU researchers Wendy Palen and Maureen Ryan considered the threat climate change poses for these amphibians. Palen, assistant professor of biology and tier two Canada research chair in aquatic conservation, explained, “For natural resource conservation issues, you cannot make the ocean less acidic. You cannot turn down the temperature on something, but in this case it has to do with these different mixes of aquatic habitats.”

According to Palen, “Fish were introduced into these mountainous landscapes and really large lakes. What that means is amphibians and a lot of the native species are restricted to other, more at-risk habitats in the landscape where fish cannot exist.” 

Currently, 95 per cent of lakes in the Pacific Northwest are stocked with non-native fish.

Palen and other researchers from the University of Washington and the University of Notre Dame began their research in US national parks with high elevations, such as Mount Rainier National Park, North Cascades National Park, and Olympic National Park. 

Palen found reason for concern: “We found that stability is likely to change in the future if some large percentage of their habitat disappears because of climate change,” she said.

“Basically, they call it the climate squeeze. If we are squeezed in one direction by fish present and then in the other direction by climate change, then the question is, ‘how much are they going to be left with in the end?’,” Palen explained.

The ponds where most of these amphibians live are going to be 50 to 80 per cent more likely to dry up in the next 50 to 100 years as opposed to present conditions. In essence, “[There] are these shallow ponds and wetlands that you see if you have ever been hiking in these mountainous areas, like a little wet meadow,” Palen said. These may be a site for exploration as fish have difficulty living in them because of the shallow nature of these ponds.

In this climate squeeze, many questions arise about the potential solutions to the problem. “How do we go in and strategically remove fish from these landscapes?” Palen posited.

“Here we might be able to forestall the effects of climate change for these amphibians by removing trout where we think there will be the biggest impact,” she continued. “We can restore some of the large, more resilient habitats and make native wetland ecosystems in the surrounding area more resilient again.”

By removing these fish — which were originally introduced for recreational purposes — Palen hopes to prevent the destruction of amphibian populations.

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