Can mercury levels in bat species along the St. Lawrence River in Ontario be used as an effective biomarker in assessing ecosystem health?

This pioneering investigation focused on the mercury bioaccumulation relationship of bats and insects. Identifying biomarkers that can be extrapolated to humans is necessary. Radio-transmitter-fitted bats were tracked to identify five of their preferred feeding sites within and outside the Cornwall Area of Concern. Bats, insects and guano were collected from the five sites.High THg levels in bats (N = 80) were noted among species and locations but these levels were not correlated with insects. Some individual Myotis lucifugus and Eptesicus fuscus bats had concentrations (10--12 ppm and 15--26 ppm) that exceeded those from previous studies (7.6 ppm and 1.5 ppm) (Hickey et al., 2001). One-way ANOVA and t-test (two-tailed) established statistical significance among caddisflies by location (p=0.0013), insect taxa (p<0.001), bat species (p=0.001) and Eptesicus fuscus by location (p=0.004). Caddisflies were sampled for MeHg (> 50% Hg was MeHg).