13 research outputs found
Predictors and immunological correlates of sublethal mercury exposure in vampire bats
Mercury (Hg) is a pervasive heavy metal that often enters the environment from anthropogenic sources such as gold mining and agriculture. Chronic exposure to Hg can impair immune function, reducing the ability of animals to resist or recover from infections. How Hg influences immunity and susceptibility remains unknown for bats, which appear immunologically distinct from other mammals and are reservoir hosts of many pathogens of importance to human and animal health. We here quantify total Hg (THg) in hair collected from common vampire bats (Desmodus rotundus), which feed on blood and are the main reservoir hosts of rabies virus in Latin America. We examine how diet, sampling site and year, and bat demography influence THg and test the consequences of this variation for eight immune measures. In two populations from Belize, THg concentrations in bats were best explained by an interaction between long-term diet inferred from stable isotopes and year. Bats that foraged more consistently on domestic animals exhibited higher THg. However, relationships between diet and THg were evident only in 2015 but not in 2014, which could reflect recent environmental perturbations associated with agriculture. THg concentrations were low relative to values previously observed in other bat species but still correlated with bat immunity. Bats with higher THg had more neutrophils, weaker bacterial killing ability and impaired innate immunity. These patterns suggest that temporal variation in Hg exposure may impair bat innate immunity and increase susceptibility to pathogens such as bacteria. Unexpected associations between low-level Hg exposure and immune function underscore the need to better understand the environmental sources of Hg exposure in bats and the consequences for bat immunity and susceptibility
Abundance and size distribution of permanent and temporary farm ponds in the southeastern Great Plains
Using aerial images from the US Department of Agriculture National Agriculture Imagery Program and the US Geological Survey National Hydrology Dataset, we estimated 577 654 farm ponds with surface areas from 0.005 to 1 ha in a 229 489 km2 region of the southeastern Great Plains (2.52 ponds/km2). Ponds with surface areas from 0.005 to 0.1 ha were the numerically dominant size class in the study region. The distribution of farm pond sizes followed an inverse power law relationship. We estimated 376 209 permanent ponds and 201 445 temporary ponds were in our study area. The ratio of temporary to permanent ponds within a pond size class was inversely related to pond surface area; 47% of ponds with surface areas of 0.005–0.1 ha were temporary, whereas only 13% of ponds with surface areas of 0.91–1 ha were temporary. Because permanent and temporary farm ponds are abundant and have different physicochemical properties and ecological communities, assessments of regional biogeochemical processes and biodiversity in the Great Plains must consider both types of ecosystems
Biomagnification of Mercury in Aquatic Food Webs: A Worldwide Meta-Analysis
The
slope of the simple linear regression between log<sub>10</sub> transformed
mercury (Hg) concentration and stable nitrogen isotope
values (δ<sup>15</sup>N), hereafter called trophic magnification
slope (TMS), from several trophic levels in a food web can represent
the overall degree of Hg biomagnification. We compiled data from 69
studies that determined total Hg (THg) or methyl Hg (MeHg) TMS values
in 205 aquatic food webs worldwide. Hg TMS values were compared against
physicochemical and biological factors hypothesized to affect Hg biomagnification
in aquatic systems. Food webs ranged across 1.7 ± 0.7 (mean ±
SD) and 1.8 ± 0.8 trophic levels (calculated using δ<sup>15</sup>N from baseline to top predator) for THg and MeHg, respectively.
The average trophic level (based on δ<sup>15</sup>N) of the
upper-trophic-level organisms in the food web was 3.7 ± 0.8 and
3.8 ± 0.8 for THg and MeHg food webs, respectively. For MeHg,
the mean TMS value was 0.24 ± 0.08 but varied from 0.08 to 0.53
and was, on average, 1.5 times higher than that for THg with a mean
of 0.16 ± 0.11 (range: −0.19 to 0.48). Both THg and MeHg
TMS values were significantly and positively correlated with latitude.
TMS values in freshwater sites increased with dissolved organic carbon
and decreased with total phosphorus and atmospheric Hg deposition.
Results suggest that Hg biomagnification through food webs is highest
in cold and low productivity systems; however, much of the among-system
variability in TMS values remains unexplained. We identify critical
data gaps and provide recommendations for future studies that would
improve our understanding of global Hg biomagnification
Supplementary material from Predictors and immunological correlates of sublethal mercury exposure in vampire bats
Mercury (Hg) is a pervasive heavy metal that often enters the environment from anthropogenic sources such as gold mining and agriculture. Chronic exposure to Hg can impair immune function, reducing the ability of animals to resist or recover from infections. How Hg influences immunity and susceptibility remains unknown for bats, which appear immunologically distinct from other mammals and are reservoir hosts of many pathogens of importance to human and animal health. We here quantify total Hg (THg) in hair collected from common vampire bats (Desmodus rotundus), which feed on blood and are the main reservoir hosts of rabies virus in Latin America. We examine how diet, sampling site and year, and bat demography influence THg and test the consequences of this variation for eight measures of immune function. In two populations from Belize, THg concentrations in bats were best explained by an interaction between long-term diet inferred from stable isotopes and year. Bats that foraged more consistently on domestic animals exhibited higher THg. However, relationships between diet and THg were evident only in 2015 but not in 2014, which could reflect recent environmental perturbations associated with agriculture. THg concentrations were low relative to values previously observed in other bat species but still correlated with bat immunity. Bats with higher THg had more neutrophils, weaker bacterial killing ability and impaired innate immunity. These patterns suggest that temporal variation in Hg exposure may impair bat innate immunity and increase susceptibility to pathogens such as bacteria. Unexpected associations between low-level Hg exposure and immune function underscore the need to better understand the environmental sources of Hg exposure in bats and the consequences for bat immunity and susceptibility
Data from: Predictors and immunological correlates of sublethal mercury exposure in vampire bats
Mercury (Hg) is a pervasive heavy metal that often enters the environment from anthropogenic sources such as gold mining and agriculture. Chronic exposure to Hg can impair immune function, reducing the ability of animals to resist or recover from infections. How Hg influences immunity and susceptibility remains unknown for bats, which appear immunologically distinct from other mammals and are reservoir hosts of many pathogens of importance to human and animal health. We here quantify total Hg (THg) in hair collected from common vampire bats (Desmodus rotundus), which feed on blood and are the main reservoir hosts of rabies virus in Latin America. We examine how diet, sampling site and year, and bat demography influence THg and test the consequences of this variation for eight immune measures. In two populations from Belize, THg concentrations in bats were best explained by an interaction between long-term diet inferred from stable isotopes and year. Bats that foraged more consistently on domestic animals exhibited higher THg. However, relationships between diet and THg were evident only in 2015 but not in 2014, which could reflect recent environmental perturbations associated with agriculture. THg concentrations were low relative to values previously observed in other bat species but still correlated with bat immunity. Bats with higher THg had more neutrophils, weaker bacterial killing ability and impaired innate immunity. These patterns suggest that temporal variation in Hg exposure may impair bat innate immunity and increase susceptibility to pathogens such as bacteria. Unexpected associations between low-level Hg exposure and immune function underscore the need to better understand the environmental sources of Hg exposure in bats and the consequences for bat immunity and susceptibility.,Becker et al 2017_Hg dataAssociated data on individual vampire bat THg (mg/kg), diet (stable isotopes), immune function, and other covariates
Data for: Mercury bioaccumulation in bats reflects dietary connectivity to aquatic food webs
Individual data for bat species, sex, sampling site, and hair THg (mg/kg) from Belize
Effects of Mercury Deposition and Coniferous Forests on the Mercury Contamination of Fish in the South Central United States
Mercury (Hg) is a toxic metal that is found in aquatic
food webs
and is hazardous to human and wildlife health. We examined the relationship
between Hg deposition, land coverage by coniferous and deciduous forests,
and average Hg concentrations in largemouth bass (<i>Micropterus
salmoides</i>)-equivalent fish (LMBE) in 14 ecoregions located
within all or part of six states in the South Central U.S. In 11 ecoregions,
the average Hg concentrations in 35.6-cm total length LMBE were above
300 ng/g, the threshold concentration of Hg recommended by the U.S.
Environmental Protection Agency for the issuance of fish consumption
advisories. Percent land coverage by coniferous forests within ecoregions
had a significant linear relationship with average Hg concentrations
in LMBE while percent land coverage by deciduous forests did not.
Eighty percent of the variance in average Hg concentrations in LMBE
between ecoregions could be accounted for by estimated Hg deposition
after adjusting for the effects of coniferous forests. Here we show
for the first time that fish from ecoregions with high atmospheric
Hg pollution and coniferous forest coverage pose a significant hazard
to human health. Our study suggests that models that use Hg deposition
to predict Hg concentrations in fish could be improved by including
the effects of coniferous forests on Hg deposition
Predictors and immunological correlates of sublethal mercury exposure in vampire bats: Online Supplemental Information
Supplementary figures and tables showing model averaging results, full model comparison, site and year effects on bat hair THg, relationships between sampling year and bat immunity, and temporal patterns in rainfall across years
Data from: Land use, season, and parasitism predict metal concentrations in Australian flying fox fur
There are two .csv files in this upload. The Pteropus_metal_data_wide.csv file contains metal concentrations (reported in ng/g) measured in fur samples collected from Pteropus flying foxes (P. alecto, P. conspicillatus, P. poliocephalus). Flying foxes were captured from 2015-2018 at multiple sites across Australia. The file also contains capture information (e.g. date, location) and biological information (e.g. species, sex, age class, parasitism) for each flying fox. The Pteropus_metadata.csv file provides further details on all column names in the primary data file, including the specific metals that were quantified. Detailed information on the study methods and results can be found in the associated Science of the Total Environment publication, Land use, season, and parasitism predict metal concentrations in Australian flying fox fur by Sánchez et al