Atrazine and estradiol effects on development of Acris blanchardi (Blanchard's cricket frog) exposed in outdoor enclosures

BACKGROUND The herbicide atrazine has been proposed as a potential endocrine disrupting compound (EDC) for amphibians. Using atrazine concentrations below or at those typically found in surface waters (0.5, 5.0, 50 mu g/L), we exposed Acris blanchardi (Blanchard's cricket frog) larvae throughout development until metamorphosis (i.e. Gosner stages 26-45). An additional 50 mu g/L treatment (50s mu g/L) was utilized where supplemented algae was added to control for indirect atrazine effects from reduced food sources. In addition to atrazine, experimental groups also included a negative control and two positive controls, 17 beta-estradiol (E2) at 2.3 and 25 mu g/L. At 60 days post-metamorphosis, A. blanchardi metamorphs were euthanized for analysis of gross and histopathological development. RESULTS Atrazine did not significantly influence mortality (mean recovery of 54% across treatments), sex ratio, body mass (BM), snout-vent length (SVL), gonad size, nor gonad development of A. blanchardi. Females exposed to 50s mu g/L atrazine had 29% less mass, were 10% shorter, and had a 29% lower mean ovary area (mm(2)) as compared to negative controls, suggesting algae enrichment had a significant negative effect. Males exposed to estradiol (25 mu g/L) showed an increased level of oviduct development. Ovary area was also significantly influenced by estradiol treatment at 2.3 and 25 mu g/L. CONCLUSION Overall, estradiol had much less effect than predicted based on other model species (e.g. Xenopus laevis). Development of A. blanchardi, overall, was not affected by long-term exposure to environmentally relevant concentrations of atrazine. However, this species also was largely insensitive to exogenous estradiol in this test system. (c) 2022 Society of Chemical Industry.