Meghan McGee is reviewing videos of two baby fathead minnows in her research lab. She explains how one fish behaves when it senses a predator nearby.
"It turns its body into this C shape and then it rapidly swims away."
By bending its body into the shape of a letter C, the fish gives itself extra propulsion to dart away from its predator. McGee's video captures this rapid movement at 1000 frames per second. But the next video shows a second fish behaving differently.
"And you see this fish takes a lot longer to respond and we see, then, the swimming away," McGee said.
That's because the second fish has been exposed to anti-depressants.
McGee is a graduate student at St. Cloud State University. She's studying cellular and molecular biology and works at the university's aquatic toxicology lab. Her work is part of ongoing research on how pharmaceuticals that end up in rivers and lakes affect aquatic life.
McGee is specifically looking at how anti-depressants affect the ability of baby fathead minnows to avoid predators. She does this by exposing some of her larval fish to realistic concentrations of anti-depressants found in the water.
McGee puts them in petri dishes where she creates vibrations that simulate those of an approaching predator. Then she studies how both sets of fish react to these vibrations.
Professor Heiko Schoenfuss oversees McGee's work. He is the head of the aquatic toxicology lab. His portion of the research focuses on adult fathead minnows.
"We find that the adult fish that are being exposed to these compounds at relatively low concentrations -- those that we measured in the environment -- when we exposed those fish for 21 days, we find that their external markings that identify them as male fish diminish in size," Schoenfuss said.
Schoenfuss is working with nest spawning fish and he says the way they defend their nests also changes when exposed to anti-depressants. Fish are either overly aggressive or too passive in defending their nests.
"And we find that some of these pharmaceuticals will actually elevate proteins in their bloodstream that we'd usually only find in female fish, not male fish," Schoenfuss said.
Schoenfuss says anti-depressants at these concentrations will not likely affect the survival of adult fish, but since they are becoming feminized, it may affect the number of offspring the fish reproduce. And that could affect the population down the road.
Schoenfuss and McGee presented these findings recently at a national meeting for the Society for Environmental Toxicology and Chemistry. Their work has been peer-reviewed and will soon be published in scientific journals such as Aquatic Toxicology, and Environmental Toxicology and Chemistry.
Schoenfuss says there is a strong interest in studying the effects of pharmaceuticals on aquatic life, but only a handful of labs around the world study these effects.
While research at SCSU focuses only on the aquatic environment, there are some parallels that can be drawn to human health effects.
"But, of course we are not surrounded by water," Schoenfuss said. "We are not exposed in the same ways, we're probably--certainly not exposed to the same concentrations. So there are some discreet differences, and there are groups that are looking into this, especially from a pharmacological point of view."
Schoenfuss says how fish exposure to pharmaceuticals affects fish consumption is also unknown.
SCSU's aquatic toxicology lab has grants from the U.S. Environmental Protection Agency and Minnesota Pollution Control Agency. The research done at SCSU is part of a multi-year effort to investigate not just pharmaceuticals in water, but also other hormone-disrupting chemicals found in household and personal care products.
Next, Meghan McGee will take her research one step further by introducing real predators to her larval fish. This will allow her to get a more realistic picture on whether fish exposed to anti-depressants are more vulnerable to predators.