Mink of the Rochester Embayment of Lake Ontario: Population Monitoring; Age, Size, and Stable Isotope Analysis; and a Predictive Model for Bioaccumulation of Chemicals of Concern

Abstract

My studies were part of a project to determine whether mink populations are negatively impacted by pollution in Lake Ontario, especially in the Rochester Embayment Area of Concern (AOC). My first study used video traps to monitor mink activity as a surrogate for mink abundance, with video traps placed in four regions: AOC: In/Inland, AOC: In/Lakeshore, AOC: Out/Inland, and AOC: Out/Lakeshore. My MustelaVision data tentatively suggest that there may be differences in abundances in mink populations inside and outside the AOC, and between the lakeshore and inland areas, but my analysis was unable to assign significance to those differences. The statistical power of my tests was low due to small sample sizes and large variability in the data, and the test was further confounded by the fact that landscape-scale features (wetland complexes) and microhabitat factors (tunnels) are key predictors of mink presence or absence at a sampling site. I also showed that mink are reproducing in the AOC, and that mink are not chiefly nocturnal. My second study used age and stable isotope data taken from mink carcasses to compare populations among the four regions, and to create a model to predict exposure levels of mink to bioaccumulative chemicals of concern (BCCs ). The Regional Descriptors (AOC: In vs. Out, Lakeshore vs. Inland, Wetland vs. Mixed habitat) had no significant effect on the ages of mink trapped, but mean ages were depressed in areas previously trapped. Mink less than one year old were trapped in each area, suggesting reproduction in all areas. ?15N values indicated that mink in the study area feed on prey at trophic level 2.5 (slightly higher along the lakeshore and in the AOC than elsewhere), with the highest level (2.8) in the Braddock Bay Wildlife Management Area. Using known concentrations of selected BCCs in Lake Ontario and trophic level calculations based on stable isotope analyses, I created a food web bioaccumulation model to predict the exposure of mink in the AOC to those BCCs.