Mercury bioaccumulation in bats reflects dietary connectivity to aquatic food webs

• Published in: Environmental pollution (1987) 2018-02, Vol.233, p.1076-1085
• Main Authors: Becker, Daniel J., Chumchal, Matthew M., Broders, Hugh G., Korstian, Jennifer M., Clare, Elizabeth L., Rainwater, Thomas R., Platt, Steven G., Simmons, Nancy B., Fenton, M. Brock
• Format: Article
• Language: English
• Subjects: Chiroptera; Ecotoxicology; Feeding guild; Phylogenetic comparative analysis; Trophic level; Trophic transfer
• ISSN: 0269-7491; 1873-6424
• DOI: 10.1016/j.envpol.2017.10.010

Mercury (Hg) is a persistent and widespread heavy metal with neurotoxic effects in wildlife. While bioaccumulation of Hg has historically been studied in aquatic food webs, terrestrial consumers can become contaminated with Hg when they feed on aquatic organisms (e.g., emergent aquatic insects, fish, and amphibians). However, the extent to which dietary connectivity to aquatic ecosystems can explain patterns of Hg bioaccumulation in terrestrial consumers has not been well studied. Bats (Order: Chiroptera) can serve as a model system for illuminating the trophic transfer of Hg given their high dietary diversity and foraging links to both aquatic and terrestrial food webs. Here we quantitatively characterize the dietary correlates of long-term exposure to Hg across a diverse local assemblage of bats in Belize and more globally across bat species from around the world with a comparative analysis of hair samples. Our data demonstrate considerable interspecific variation in hair total Hg concentrations in bats that span three orders of magnitude across species, ranging from 0.04 mg/kg in frugivorous bats (Artibeus spp.) to 145.27 mg/kg in the piscivorous Noctilio leporinus. Hg concentrations showed strong phylogenetic signal and were best explained by dietary connectivity of bat species to aquatic food webs. Our results highlight that phylogeny can be predictive of Hg concentrations through similarity in diet and how interspecific variation in feeding strategies influences chronic exposure to Hg and enables movement of contaminants from aquatic to terrestrial ecosystems. [Display omitted] •Total mercury was determined in hair from 98 bats from 22 species in Belize.•Dietary guild was the best predictor of hair THg in Belizean bats.•Frugivores had lowest THg (μ = 0.04 mg/kg) while a single piscivore (Noctilio leporinus) showed highest THg (145.27 mg/kg).•Hair THg showed strong phylogenetic signal across 50 bat species from this study and the literature (Pagel's λ = 0.97).•Bat species that consumed more potentially aquatic prey (e.g., invertebrates, ectotherms, fish) showed the highest THg.