By Jade Garcia, CSE communications intern

Ray Drenner, Ph. D., professor and chair of biology, and Matt Chumchal, Ph. D., assistant professor, are researching two aspects of mercury (Hg) contamination: fish in the south central United States and aquatic insect transport of Hg to terrestrial environments.

The first major area of research is examining the relationship between Hg deposition from the atmosphere, forest coverage and average concentration in largemouth bass in 14 ecoregions within six states. Eleven of the 14 areas had average Hg concentrations in the fish above 300 ng/g, which is the threshold concentration recommended for fish consumption advisories. The percent land coverage by coniferous forests was strongly correlated with the average Hg in the fish while percent land coverage by deciduous forest was not.

This study is very important to many people because methyl mercury (MeHg) is one of the most pervasive and hazardous contaminants in the environment, and it affects the health of both wildlife and humans. This is the first study showing that landscape coverage by coniferous forests is correlated with increased concentrations of Hg in fish. Drenner and Chumchal’s research suggests that humans who consume freshwater fish may be at an increased risk for Hg exposure if they eat fish from areas of the southern United States covered by coniferous forests.

The second major area of research focuses on how aquatic insects transport Hg to terrestrial environments. Drenner and Chumchal studied the effects of fish on mercury in insects that emerge from aquatic ecosystems (such as dragonflies, damselflies). The fish acted as size-selective predators and reduced MeHg by suppressing the emergence of large insects while not affecting the smaller insects.

The transfer of contaminants from water to land ecosystems is an emerging environmental concern. Drenner and Chumchal’s research is the first to experimentally show the level of mercury pollution and predation by fish influences the cross-system transportation of MeHg from water to land ecosystems.