Trophic position, altitudinal distribution, and water dependence as determining factors for mercury concentrations in tropical montane anurans

• Published in: The Science of the total environment 2022-02, Vol.806 (Pt 3), p.151356-151356, Article 151356
• Main Authors: Drummond, Leandro de Oliveira, Meire, Rodrigo Ornellas, Braga, Caryne, Rezende, Carlos Eduardo de, Malm, Olaf, Cerqueira, Rui
• Format: Article
• Language: English
• Subjects: Amphibians; Animals; Anura; Atlantic Rainforest; Conservation; Ecosystem; Ecotoxicology; Environmental Monitoring; Humans; Mercury - analysis; Stable isotopes; Topsoil; Water; Water Pollutants, Chemical - analysis
• ISSN: 0048-9697; 1879-1026
• DOI: 10.1016/j.scitotenv.2021.151356

Mercury (Hg) is a widespread and toxic contaminant with potential for long-range atmospheric transport. Previous work has shown that temperate and subtropical montane ecosystems have great potential for deposition of this element. However, little information exists regarding Hg dynamics in tropical mountains. In present study, we evaluated the influence of altitudinal distribution, size, trophic position, and degree of water dependence on Hg concentration in amphibians. For this purpose, we determined the mercury concentration in topsoil and amphibian samples collected at 32 points distributed between 327 and 2181 m above sea level in Serra dos Órgãos, a mountainous complex located in southeastern Brazil. We analyzed the concentration of mercury in whole body samples of 200 individuals of 30 amphibian species. Trophic position of the specimens was estimated by nitrogen stable isotope (δ15N) composition in muscle tissues. We observed a positive relationship between elevation and Hg concentration in topsoil samples from rainforest sites. However, in samples from nebular forest and campos de altitude (highland grasslands) sites, the concentration of Hg was considered lower than expected by the trend in rainforest points, indicating that the vegetation structure plays an important role in the deposition of atmospheric mercury. Mercury concentration in amphibians varies according to the functional characteristics of the species and the environment in which the individual is inserted. Elevation, trophic level and water dependence explained at least some degree of variation in Hg concentration in amphibian tissues. Thus, this community-level analysis suggests that mountainous areas in the tropical region, as recorded for temperate and subtropical mountains, act as regional convergence and deposition sites for atmospheric mercury. [Display omitted] •We evaluated Hg concentration in 200 individuals of 30 amphibian species.•Elevation, water dependence and δ15N are good predictor of Hg content in amphibians.•Body weight is a poor predictor of Hg content in amphibians.•Topsoil Hg content increases with elevation in tropical montane rainforests.•Topsoil of cloud forests and campos de altitude has low Hg concentrations