Persistent organochlorine pesticides in two hylidae species from the La Antigua watershed, Veracruz, Mexico.

ABSTRACT

Amphibians are good models for monitoring contaminants in ecosystems because they transfer xenobiotic substances throughout trophic networks. We quantified bioaccumulated POCs by capturing and sacrificing ninety-one frogs (Charadrahyla taeniopus and Ecnomiohyla miotympanum) from four riverine forests immersed in agriculture and pasture lands in the La Antigua, Veracruz, Mexico watershed. The concentrations of ∑DDTs, ∑HCHs, ∑Endosulphans, ∑Heptachlors, ∑Drines, and ∑Chlordanes were measured by gas chromatography and compared between species, sites and seasons. In E. miotympanum the concentration of ∑HCHs was highest at 4,746.46 µg/g, while in C. taeniopus that of the ∑DDTs was highest at 2,637.10 µg/g. Concentrations of ∑Endosulphans, ∑HCHs, ∑Chlordanes and ∑Drines differed between the two species, and were always higher in E. miotympanum. In E. miotympanum the concentration of ∑Drines differed between sites, while for C. taeniopus ∑Heptachlors differed between seasons and ∑Drines among sites. These findings indicate that the two frog species even bioconcentrate POCs that are banned and may disrupt their reproduction. The effect however may vary according to the site and the frog species.