Date of Award
Master of Science
Anthropogenic alteration of the environment began as soon as people settled the Great Lakes (GL) region with hydrologic alteration (dams) and discharges of man-made chemicals into the air and water as populations and industry expanded. Consequently, the GL became a reservoir of anthropogenic contaminants such as mercury (Hg), polychlorinated biphenyls (PCBs), dichloro-diphenyl-trichloroethylene (DDT), and organochloride compounds. Migratory fish accumulate and magnify contaminants within their tissues and transport them across ecosystem boundaries. Re-established connectivity in the form of dam removal has the potential to allow contaminant laden migrants access to ecosystems previously inaccessible. Here I assess the contaminant burden of a subset of GL migrants and stream resident trout in the Boardman River, MI. GL migrants had similar or greater concentrations of POPs in their eggs versus whole body samples. There was a marked difference in Hg with eggs having far lower Hg levels than whole body samples. These differences reflect differing bioaccumulation pathways between tissue types and contaminant type. Hg, POPs, and PCB congener patterns were compared between open and closed reaches with different patterns present in trout from each reach type. Congener patterns of open trout closely resembled the congener pattern of GL migrant eggs indicating these are a dominant source of POP contamination in stream residents. Ultimately migration size, contaminant concentration, and egg mass influence contaminant deposition in spawning streams with introduced Pacific salmon representing a greater risk than native suckers.
Gay, Ross A., "PREDICTING CONTAMINANT TRANSFER FOLLOWING RE-ESTABLISHED CONNECTIVITY IN THE BOARDMAN RIVER" (2022). All NMU Master's Theses. 735.