Samplings: December 2006/January 2007

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Eastern elliptio mussels such as the ones pictured above were studied for the effects of fluoxetine exposure on breeding.

Chris Eads, North Carolina State University

The freshwater mussels of North America are in trouble. Of 300 native species, some 70 percent are extinct, endangered, or declining. Invasives such as the zebra mussel have been, er, muscling them out of lakes and streams; development and pollution are also threatening their habitats. Now the beleaguered bivalves must add yet another peril to their list of woes: a new study shows that the widely prescribed antidepressant Prozac, a common pollutant, interferes with their reproduction. Like other drugs, Prozac often ends up in lakes and streams after being excreted and making its way through a wastewater-treatment plant. Fluoxetine hydrochloride, its active ingredient, boosts the concentration of the neurotransmitter serotonin in the brain.

To test its effect on mussels, Rebecca M. Heltsley, a biologist at the National Institute of Standards and Technology in Charleston, South Carolina, and several colleagues placed female eastern elliptio mussels in tanks of water laced with serotonin, or with fluoxetine hydrochloride at various concentrations, some matching the levels that commonly occur in bodies of freshwater. All the mussels were carrying larvae; within forty-eight hours, mussels in each tank had prematurely released their larvae, which were often too immature to survive. The greater the concentration of fluoxetine hydrochloride, the more larvae were released. Better filtering of sewage would give freshwater mussels a less depressing outlook, says Heltsley. (Presented at the national meeting of the American Chemical Society, September 2006)