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Darren Lerner

by Tracey Crago, WHOI Sea Grant

Darren Lerner is a busy guy who is about to get even busier—with a lot less sleep. As if working full time as a research physiologist in the S.O. Conte Anadromous Fish Research Center in Turners Falls, Mass., wasn't enough, Lerner decided to pursue a Ph.D. from UMass Amherst's Organismic and Evolutionary Biology program. And in June, he and his wife are expecting their first child.

Fortunately Lerner, a Massachusetts native, understands stress: it is one of the things he looks for in Atlantic salmon that have been exposed to contaminants. Along with Steve McCormick, his boss at the Conte lab and now his doctoral advisor, Lerner is in the midst of a Woods Hole Sea Grant-funded study to investigate the developmental effects of contaminants—PCBs and nonylphenol (NP)—on salinity preference and seawater survival in Atlantic salmon.

Lerner has been interested in endocrinology and physiology since he was a graduate student at Oregon State University. He earned his master's degree working with snakes, but began studying fish in 1998 while working for a USGS lab in Oregon. He returned to his home state in 2000 to work at the Conte lab and entered the UMass Ph.D. program in 2002.

In the first phase of the Sea Grant study, Lerner and McCormick treated sac fry and pre-smolt salmon with two doses of NP for three weeks. At the end of the treatment period, 50 percent of the treated sac fry salmon died after being exposed to NP at levels known to exist in the environment. Pre-smolts were treated for the same three-week period, then transferred to a specially designed saltwater­freshwater tank where their salinity preference and behavior were observed for six hours.

"It did not appear that there was much of a difference between treated and untreated salmon in terms of their freshwater­ saltwater choice," says Lerner, "but we did see a significantly greater stress response in treated fish—50­60 percent—than in control animals.

"We subjected the fish to a handling stressor similar to what they might experience when they encounter a dam during downstream migration," he says. To measure stress, Lerner samples the blood for cortisol and other stress hormones. Typically, stress hormone levels peak within a 2-3 hour period, plateau, then decrease to a pre-stress level within a 24-hour period. Lerner will be looking to see if exposure to contaminants impairs the ability of the salmon to recover from stress.

Lerner and McCormick are now replicating the tests with PCBs, which are known to have disruptive effects on the thyroid and stress hormone. In addition, he will continue the NP tests on sac-fry survivors from last year's study—now pre-smolts. Once the project is completed, Lerner envisions a follow-on study. "I'd like to test exposure at multiple stages, representing three significant developmental changes."

If work translates to personal life, studying multiple stress effects in salmon may have prepared Lerner for his full plate of professional and personal commitments. Perhaps he could measure his own stress hormone levels to answer his question, "are high levels of stress hormones a good thing or a bad thing?"

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