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
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?"