First report of microplastics in the gastrointestinal tracts of North American insectivorous bats.

BACKGROUND

Microplastics (MPs) are among the many ubiquitous environmental contaminants of emerging concern for both aquatic and terrestrial species. Bats have integral roles in aquatic-terrestrial food webs on almost every continent, are exposed to a wide variety of environmental contaminants, and yet have received limited investigation about the threat of MPs. While MPs have been detected in numerous bird species and in bats of the Amazon, there are no published studies documenting the dietary MP exposure of North American bats that consume many terrestrial and aquatic arthropods or the possible adverse effects of exposure.

METHODS

We chemically digested bat gastrointestinal tracts (GITs) to extract, quantify, and characterize MPs that accumulated in insectivorous Eptesicus fuscus (big brown bats). We quantified MPs in procedural blanks to account for background contamination in the lab for controls and compared concentrations in bat GITs to controls. We measured the mass of bat carcasses, minus the brains, prior to necropsy to determine body condition. We investigated the relationship between MP concentrations in bat GITs to body condition to determine if higher concentrations indicated reduced bat body condition using linear regression.

RESULTS

Our results indicate that the ingestion of MPs by bats could lead to lower bat mass, potentially related to poorer body condition or ability to store fat. The ability to store and use fat is crucial for the survival of these migrating and cave-hibernating species. Moreover, bats with higher fat stores are more likely to survive multiple stressors such as the non-native fungal disease white-nose syndrome. This study will allow future research to build off baseline information and further explore the effects of MPs to individuals and populations of bats of conservation concern.