Mercury bioaccumulation in bats reflects dietary connectivity to aquatic food webs

Environmental Pollution

DANIEL BECKER, DANIEL.BECKER3@MONTANA.EDU

Mercury is a heavy metal that, when accumulated in an organism, leads to neurotoxic effects. The bioaccumulation of Mercury among aquatic food webs is well studied, but Mercury’s effect on terrestrial consumers has not been studied in depth. A terrestrial consumer’s dietary guild that contains the aquatic food web could coincide with excessive Mercury ingestion. Different species of bats vary widely in consumption habits: dietary guilds range from frugivory and nectarivory to insectivory, sanguivory, carnivory, and several instances of piscivory. This quality makes bats a preferred organism for measuring the trophic transfer of Mercury. Here, Daniel Becker and his group captured several bat species in Belize and later analyzed the hair THg levels. This data was then analyzed with linear models, linear mixed models, and phylogenetic comparative methods to determine if connectivity to aquatic food webs could explain the interspecific variation in Mercury levels. It was determined that dietary guild was strongly important in variation in THg but potential predation on the aquatic food web was most significant. The data indicate that THg is greatest in insectivorous, carnivorous, and piscivorous bats, species that are more likely to feed on aquatic prey. This suggests that Mercury bioaccumulation is increased not only with trophic level but also with dietary connectivity to aquatic ecosystems. This study provides a framework for predicting which species will have health and fitness impacts due to long-term Mercury exposure.