UNIVERSITY PARK, Pa. — Brook trout may have a genetic trick up their scales when it comes to adapting, with limitations, to heatwaves that threaten their existence. Scientists have known for years that brook trout — an iconic coldwater fish species native to streams and lakes in the eastern United States and Canada — are extremely vulnerable to warming temperatures, with more than half of their habitats characterized as highly sensitive and highly vulnerable to such changes by U.S. Forest Service researchers in 2010. Now, a novel study led by researchers at Penn State suggests that brook trout are capable of mounting a protective genetic response to thermal stress that can be passed on from one generation to the next.
“The responses to heat stress had a high degree of plasticity, with brook trout exhibiting the ability to acclimate and increase tolerance to higher temperatures,” said team leader Jason Keagy, assistant research professor of wildlife behavioral ecology. “Our study covered two heatwaves, and the overall change in expression patterns was more intense during the second heatwave. We think the first heatwave ‘primed’ the response for the second.”
In findings recently published in Science of the Total Environment, the researchers reported that groups of genes involved in immune response and oxygen-conveying activity were upregulated and downregulated, respectively, at higher water temperatures in two successive heat waves in July and August 2022 in four small central Pennsylvania mountain streams.
“Detecting these gene-expression fingerprints of thermal stress allows us to directly ‘ask’ the fish how they are feeling, whether they are stressed out,” Keagy said.