An Evaluation of the Occurrence of Micronuclei and other Nuclear Abnormalities in Fishes from the Great Lakes Basin, United States

Biological markers (biomarkers) sensitive to genotoxic and mutagenic contamination in fishes are widely used to identify contamination in the aquatic environment. The fish tumors or other deformities biological use impairment (BUI) occurs at 18 of the 30 areas of concern (AOC) located in the Great Lakes basin within the United States. As each AOC evaluates this specific BUI for possible delisting, biomarkers sensitive to both genotoxic and mutagenic chemicals can be integrated as a possible criterion for delisting. The micronucleus assay identifies genotoxic contamination by observing the presence of a micronucleus (MN), along with a primary nucleus within the cellular body. Nuclear abnormalities (NA) such as notching, lobes, blebbing, and binucleation are observed from the nuclear membrane and are indicators for mutagenic contamination. The micronucleus assay was incorporated to assess genotoxic and mutagenic contamination among sites, species, and season from fish collected from 8 AOC\u27s, as well as 1 non-AOC site during the spring and fall, 2011. Micronuclei and/or NA were observed at all sites. Micronuclei were observed at differing occurrence rates among species. Brown bullhead (Ameiurus nebulosus ) expressed MN at a lower rate when compared to either largemouth bass (Micropterus salmoides) or smallmouth bass ( Micropterus dolomieu). White sucker (Catostomus commersoni ) express MN at a lower rate when compared to smallmouth bass. Nuclear abnormalities rates exactly followed these trends. Brown bullhead tended to express MN and NA at a lower rate during the fall as compared to individuals collected in the spring. Largemouth bass tended to express MN and NA at a higher rate during the spring. Moving forward, this apparent site and species effect should be considered when evaluating genotoxic and mutagenic contamination