Invasive species may exacerbate PCB contamination problem in Green Bay

Ann Arbor, Mich. — Green Bay, Lake Michigan, has long been known for its high PCB levels, as evidenced by notices posted along the waterfront that warn against consumption of certain aquatic species. PCBs primarily accumulate in sediments, but the trophic pathways of how the contaminants are transferred to walleye, yellow perch, smallmouth bass, and other species of interest are not well understood. Previous studies have shown that the internal flow patterns of Green Bay deposit PCB-laden sediments from Fox River along Door Peninsula’s rocky western shore. Coincidentally, this is where colonization by invasive species from the Black and Caspian Seas, sequentially—zebra mussel, round goby and quagga mussel—has been taking place over the past two decades.

We used a technique called congener-specific analysis to quantify PCB concentrations in round goby and mussel samples from ten sites along the rocky nearshore area. We found that these highly localized, bottom-dwelling invasive species accumulate PCBs in a pattern similar to that observed in sediments farther offshore. This interaction indicates an entry point for PCBs into the food web. Entry of PCBs in this manner could have far reaching consequences because the rocky nearshore regions serve as a nursery for juvenile population of many fish species that are of recreational and economic importance. We also found that juvenile round gobies have a distinct diet that leads to smaller fish accumulating higher levels of PCBs than larger ones. All of these findings suggest that the invasions of zebra mussel, round goby and quagga mussel may mobilize PCBs out of sediments into the food web and thus, exacerbate PCB contamination problems in Green Bay.

Original Publication Information

Results of this study, "PCBs Refocused: Correlation of PCB Concentrations in Green Bay Legacy Sediments with Adjacent Lithophilic, Invasive Biota," are reported by Sarist Macksasitorn, John Janssen, and Kimberly A. Gray in Volume 41, Issue 1 of the Journal of Great Lakes Research, published by Elsevier, 2015.

Contacts

For more information about the study, contact Kimberly A. Gray, Department of Civil and Environmental Engineering, Northwestern University, 2145 Sheridan Road, Evanston, Illinois, 60208; [email protected].

For information about the Journal of Great Lakes Research, contact Stephanie Guildford, Scientific Co-Editor, Large Lakes Observatory, University Minnesota Duluth, 2205 East Fifth Street, Duluth, Minnesota, 55812-2401; [email protected]; (218) 726-8064.