Habitat loss and fragmentation together represent the most significant threat to the world's biodiversity. In order to guarantee the survival of this diversity, the monitoring of bioindicators can provide important insights into the health of a natural environment. In this context, we used the comet assay and micronucleus test to evaluate the genotoxic susceptibility of 126 bats of eight species captured in soybean and sugarcane plantation areas, together with a control area (conservation unit) in the Cerrado savanna of central Brazil. No significant differences were found between the specimens captured in the sugarcane and control areas in the frequency of micronuclei and DNA damage (comet assay). However, the omnivore Phyllostomus hastatus had a higher frequency of nuclear abnormalities than the frugivore Carollia perspicillata in the sugarcane area. Insectivorous and frugivorous bats presented a higher frequency of genotoxic damage than the nectarivores in the soybean area. In general, DNA damage and micronuclei were significantly more frequent in agricultural environments than in the control area. While agricultural development is an economic necessity in developing countries, the impacts on the natural landscape may result in genotoxic damage to the local fauna, such as bats. Over the medium to long term, then DNA damage may have an increasingly negative impact on the wellbeing of the local species.

Artificial illumination at night represents an increasingly concerning threat to ecosystems worldwide, altering persistence, behaviour, physiology and fitness of many organisms and their mutual interactions, in the long-term affecting ecosystem functioning. Bats are very sensitive to artificial light at night because they are obligate nocturnal and feed on insects which are often also responsive to lights. Here we tested the effects of LED lighting on prey-predator interactions at riverine ecosystems, using bats and their insect prey as models, and compared bat and insect reactions in terms of bat activity and prey insect abundance and diversity, respectively, on artificially lit vs. unlit nights. Artificial light influenced both insect and bat assemblages in taxon-specific directions: insect abundances increased at lit sites, particularly due to an increase in small dipterans near the light source. Composition of insect assemblages also differed significantly between lit and unlit sites. Total bat activity declined at lit sites, but this change was mainly due to the response of the most abundant species, Myotis daubentonii, while opportunistic species showed no reaction or even an opposite pattern (Pipistrellus kuhlii). We show that artificial lighting along rivers may affect trophic interactions between bats and insects, resulting in a profound alteration of community structure and dynamics.

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.

The Banana Bat, Neoromicia nana, exploits pollution-tolerant chironomids at wastewater treatment works (WWTWs). We investigated how pollutant exposure impacts the detoxification organs, namely the liver and kidney of N. nana. (i) We performed SEM-EDS to quantify metal content and mineral nutrients, and found significant differences in essential metal (Fe and Zn) content in the liver, and significant differences in Cu and one mineral nutrient (K) in the kidneys. (ii) We performed histological analysis and found more histopathological lesions in detoxification organs of WWTW bats. (iii) We calculated hepatosomatic/renalsomatic indices (HSI/RSI) to investigate whole organ effects, and found significant increases in organ size at WWTWs. (iv) We quantified metallothionein 1E (MT1E), using Western Blot immunodetection. Contrary to predictions, we found no significant upregulation of MT1E in bats at WWTWs. Ultimately, N. nana exploiting WWTWs may suffer chronic health problems from sub-lethal damage to organs responsible for detoxifying pollutants.

Total mercury (Hg) concentrations were measured in archived fur from adult female little brown bats sampled at maternity roosts across Atlantic Canada. Mercury concentrations varied significantly among regions and roosts. Bats from Nova Scotia and Newfoundland had the highest median Hg concentrations (9.67 μg/g and 9.51 μg/g) among regions, and individuals from Kejimkujik National Park had the highest Hg (median: 28.38 μg/g) among roosts. Over one third of individuals sampled had fur Hg concentrations exceeding thresholds associated with neurochemical responses. Within-roost examinations of stable carbon and nitrogen isotopes in fur showed inconsistent associations with Hg concentrations. Therefore, the hypothesis that within-roost variation in Hg is driven by variation in diet is not supported by this data, and it is recommended that key prey items be included in future mercury bioaccumulation studies for bats. The elevated mercury fur concentrations for bats from southern Nova Scotia remains an anomaly of concern even when placed in the larger context of Atlantic Canada.

Populations of some species of bats are declining in some regions of Europe. These declines are probably due to a range of pressures, including climate change, urbanization and exposure to toxins such as metals. This paper describes the development, paramaterisation and application of a spatially explicit modeling framework to predict the risks of soil-associated metals (lead, copper, zinc and cadmium) to bat health. Around 5.9% of areas where bats reside were predicted to have lead levels that pose a risk to bat health. For copper, this value was 2.8%, for cadmium it was 0.6% and for zinc 0.5%. Further work is therefore warranted to explore the impacts of soil-associated metals on bat populations in the UK.

The aim of this novel research was to determine the toxic burden of increased elements in water resources on the inhabitant wild animals (squirrels, turtles, bats), using particle induced x-ray emission (PIXE) and histopathological approaches. PIXE analysis of skin, muscle, lung, liver and kidney revealed significant increase in Al, Cl, Fe, Mg, Mn, Si and V. Moreover, data clearly reflect a significant (P < 0.001) deposition of toxic elements (Al, Cl, Fe and K) in the lung producing interstitial/proliferative pneumonitis, intra-alveolar hemorrhages, and thickening of alveolar capillary walls. The results obtained from the liver samples emphasized that majority of the animals were intoxicated with Cl, Mg, S, Si and V, which have produced profound deterioration and swelling of the hepatocytes. Likewise, histopathology of the kidney sections spotlighted severe nephritis and degenerative changes, which could be associated with the elevated amount of Al, Cl and Mg. This data undoubtedly provide relevant information on the heavy burden of toxic elements and their pathological outcomes in wild animals and highlight their potential risks for human exposure. Thus, the information provided is critical for developing effective strategies in dealing with health hazards associated with elemental exposures.

Increasing levels of artificial light at night (ALAN) are a major threat to global biodiversity and can have negative impacts on a wide variety of organisms and their ecosystems. Nocturnal species such as bats are highly vulnerable to the detrimental effects of ALAN. A variety of lighting management strategies have been adopted to minimise the impacts of ALAN on wildlife, however relatively little is known about their effectiveness. Using an experimental approach, we provide the first evidence of negative impacts of part-night lighting (PNL) strategies on bats. Feeding activity of Myotis spp. was reduced along rivers exposed to PNL despite no reduction in overall bat activity. We also provide the first evidence of negative effects of PNL on both feeding and activity for Pipistrellus pipistrellus which has previously been recorded feeding under artificial light. Despite having considerable energy-saving benefits, we outline the potential negative impacts of PNL schemes for bats in riparian habitats. PNL are unlikely to provide desired conservation outcomes for bats, and can potentially fragment important foraging habitats leading to a breakdown of functional connectivity across the landscape. We highlight the potential dichotomy for strategies which attempt to simultaneously address climate change and biodiversity loss and recommend alternative management strategies to limit the impacts of ALAN on biodiversity.

Bats are poorly understood as a reservoir of multidrug-resistant strains; therefore, the aim of this study was to determine molecular characterization of multidrug-resistant Enterococcus strains isolated from bat species from Poland. A multi-stage analysis based on targeted isolation of drug-resistant strains (selective media with tetracycline, chloramphenicol, gentamicin, streptomycin, and vancomycin), determination of the phenotypic profile of drug-susceptibility using the disc diffusion method, and amplification of DNA fragments surrounding rare restriction sites (ADSRRS-fingerprinting) was used for the isolation and differentiation of strains. The applied strategy finally allowed identification of E. faecalis resistant to at least one antimicrobial in 47.2% of the single-animal group and in 46.9% of the pooled samples of bat’s guano. Out of the 36 distinct isolates, 69% met the criteria of multi-drug resistance, with a dominant combination of resistance to tetracycline, erythromycin, and rifampicin. Simultaneously, 41.6% of the strains were high-level aminoglycoside resistant (HLAR). In most strains, phenotypic resistance was reflected in the presence of at least one gene encoding resistance to a given drug. Moreover, our research results show that some genes were detected simultaneously in the same strain statistically significantly more frequently. This may confirm that the spread of some genes (tetM and ermB or aph (3′)-IIIa as well as gelE and aac (6′)-Ie-aph (2″)-Ia or ant (6)-Ia) is associated with their common occurrence on the same mobile genetic element.To our knowledge, this is the first analysis of multidrug-resistance among E. faecalis isolated from bats. Our research demonstrates that the One Health concept is not associated exclusively with food-producing animals and humans, but other species of wildlife animals should be covered by monitoring programs as well.We confirmed for the first time that bats are an important reservoir of multi-resistant E. faecalis strains and could have a great impact on environmental resistance.

All European bats are protected by the EU and Associated Members legal regulations. Being insectivorous and top predators, they can be particularly exposed to persistent organic and inorganic pollutants. It is surprising how little is known about the impact of environmental pollutants on bats from physiological to populational levels. In this study we focused on contamination with trace metals of first-year bats from Kharkiv city, NE Ukraine. Tissues from the carcasses of two species, Nyctalus noctula (n = 20) and Eptesicus serotinus (n = 20), were used for metal analysis. The samples of external (wing membrane, fur) and internal (liver, lung, kidney, bones) tissues were analysed for contents of Pb, Cu, Zn, and Cd to see whether fur or wing membrane can be used as proxies for metal contamination of the vital internal tissues. In E. serotinus, significant positive correlations in Pb concentrations were found between all external and internal tissues. For Cd only, correlation between the fur and lung was found, for Cu between the fur and liver, and for Zn between the fur and kidney. In contrast, for N. noctula, only one such correlation was found – between Zn concentrations in the fur and kidney. The tissues differed significantly in concentrations of all studied metals, with no difference between the species. The results showed that the fur and wing membrane can be used as good proxies for Pb concentrations in internal organs of E. serotinus, but not necessarily for other metals or for N. noctula. The results for Pb are, however, encouraging enough to conclude that the topic is worth further studies, covering more species, a wider age range and more diverse environments.