Disentangling interactions among mercury, immunity, and infection in a Neotropical bat community

Contaminants such as mercury are pervasive and can have immunosuppressive effects on wildlife. Impaired immunity could be important for forecasting pathogen spillover risks, as many land-use changes that generate mercury contamination also bring wildlife into close contact with humans and domestic animals. However, the interactions among contaminants, immunity, and infection are difficult to study in natural systems, and empirical tests of possible directional relationships remain rare.
We capitalized on extreme mercury variation in a diverse bat community in Belize to test association among contaminants, immunity, and infection. By comparing a previous dataset of bats sampled in 2014 with new data from 2017, representing a period of rapid agricultural land conversion, we first confirmed bat species more reliant on aquatic prey had higher fur mercury. Bats in the agricultural habitat also had higher mercury in recent years. We then tested covariation between mercury and cellular im...