Effect of pH and release® on two life stages of four anuran amphibians

Using three native Canadian and one exotic anuran species, the interactive toxicity of pH and the forestry usedherbicide Release® (triclopyr [3,5,6‐trichloro‐2‐pyridl‐oxyacetic acid]) was assessed. Embryonic and larval (Gosner 25) stages of Rana pipiens, Rana clamitans, Bufo americanus, and Xenopus...

Ausführliche Beschreibung

Gespeichert in:
Bibliographische Detailangaben
Veröffentlicht in:Environmental toxicology and chemistry 2003-11, Vol.22 (11), p.2673-2678
Hauptverfasser: Edginton, Andrea N., Stephenson, Gerald R., Sheridan, Patrick M., Thompson, Dean G., Boermans, Herman J.
Format: Artikel
Sprache:eng
Schlagworte:
Online-Zugang:Volltext
Tags: Tag hinzufügen
Keine Tags, Fügen Sie den ersten Tag hinzu!
Beschreibung
Zusammenfassung:Using three native Canadian and one exotic anuran species, the interactive toxicity of pH and the forestry usedherbicide Release® (triclopyr [3,5,6‐trichloro‐2‐pyridl‐oxyacetic acid]) was assessed. Embryonic and larval (Gosner 25) stages of Rana pipiens, Rana clamitans, Bufo americanus, and Xenopus laevis were exposed to treatments for at least 96 h in a staticrenewal system using a central composite rotatable design. Mortality and the prevalence of malformations were modeled using generalized linear models with a profile deviance approach to obtain confidence intervals. Consistent trends of greater toxicity with lower pH were observed, with the majority of models (five of seven models) showing significant (p < 0.05) inverse relations. Larval lethal concentration estimates were eight to twenty‐three times less than those observed for embryos, indicating that the larval stages were more sensitive to treatments. Further, the median lethal concentration (LC50) values for the larvae were below the expected environmental concentration (EEC) as calculated by Canadian regulatory authorities for Release. Species sensitivity was similar, with an average larval 96‐h LC50 of 0.89 mg acid equivalents (AE)/L at pH =.5 and 1.6 mg AE/L at pH 7, suggesting that X. laevis is a reasonable surrogate for native amphibians in laboratory toxicity testing. For the embryo tests, R. pipiens were slightly less sensitive in comparison with the other three species. Based on a hazard quotient analysis (EEC/LC50 > 1) for the most sensitive larval life stages, higher tier ecotoxicological testing under more realistic environmental conditions is strongly recommended.
ISSN:0730-7268
1552-8618
DOI:10.1897/02-484