Agricultural intensity in ovo affects growth, metamorphic development and sexual differentiation in the Common toad (Bufo bufo)
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Pollution was cited by the Global Amphibian Assessment to be the second most important cause of amphibian decline worldwide, however, the effects of the agricultural environment on amphibians are not well understood. In this study, spawn from Bufo bufo was taken from four sites in England and Wales with varying intensities of arable agriculture. Spawn was either placed in tanks containing aged tap water (ex-situ, five replicates) or in cages at the native site (caged, five replicates). Hatching success, abnormal tadpoles, and forelimb emergence were recorded during the larval stage. Individuals were also sampled at five time points (TP) during development (5-, 7-, 9-, 12-, 15-weeks post-hatch) and analysed for morphological parameters. The thyroids (TP2) and the gonads (TP3,4,5) were also analysed histologically. With the exception of the thyroid histopathology, all analysed endpoints were significantly different between ex-situ individuals reared under identical conditions from the different sites. In addition, intensity of arable agriculture had a negative effect on growth and development. At one site, despite distinct rearing conditions, a high level of intersex (up to 42%) and similar sex ratios were observed in both ex-situ and caged individuals. Taken together, these data suggest that maternal exposure and/or events in ovo had a much larger effect on growth, metamorphic development, and sexual differentiation in B. bufo than the ambient environment. This could have important implications for traditional exposure scenarios that typically begin at the larval stage. Intersex is reported for the first time in European amphibians in situ, highlighting the potential use of distinct populations of amphibians in fundamental research into the aetiology of specific developmental effects in wild amphibians.
KeywordsAmphibian Pollution Pesticides Herbicides Endocrine disruption Intersex
Funding from DEFRA gratefully acknowledged. Also, the generous sharing of amphibian databases from Froglife (registered charity: 1093372).
- Carr JA, Gentles A, Smith EE, Goleman WL, Urquidi LJ, Thuett K, Kendall RJ, Giesy JP, Gross TS, Solomon KR, Van der Kraak G (2003) Response of larval Xenopus laevis to atrazine: assessment of growth, metamorphosis, and gonadal and laryngeal morphology. Env Tox Chem 22(2):396–405Google Scholar
- DEFRA (2005) e-Digest statistics about: Inland water quality and use. http://www.defra.gov.uk/environment/statistics/inlwater/iwgroundwater.htm. Retrieved January 2007
- GAA (2004) http://www.iucnredlist.org/initiatives/amphibians/analysis/major-threats. Retrieved Nov 2009
- Gruca S, Michalowski J (1961) The rate of development of gonads against the backdrop of the development of the whole organism in the tadpole Xenopus laevis Daud. Acta Biol Cracoviensia Ser Zool 4:191–197Google Scholar
- Harris RN (1999) The anuran tadpole: evolution and maintenance. In: McDiarmid RW, Altig R (eds) Tadpoles: the biology of anuran larvae. University of Chicago Press, Chicago, pp 279–294Google Scholar
- McDaniel TV, Martin PA, Struger J, Sherry J, Marvin CH, McMaster ME, Clarence S, Tetreault G (2008) Potential endocrine disruption of sexual development in free ranging male northern leopard frogs (Rana pipiens) and green frogs (Rana clamitans) from areas of intensive row crop agriculture. Aquat Toxicol 88(4):230–242CrossRefGoogle Scholar
- OECD (2007) Series on testing and assessment. Guidance document on amphibian thyroid histology. Environmental Health and Safety Publications, Paris, FranceGoogle Scholar
- Rugh R (1951) The frog: its reproduction and development. McGraw-Hill Book Company, Inc, New YorkGoogle Scholar
- Smith EE, Du Preez LH, Gentles A, Solomon KR, Tandler B, Carr JA, Van der Kraak GL, Kendall RJ, Giesy JP, Gross TS (2005) Assessment of laryngeal muslce and testicular cell types in Xenopus laevis (Anura Pipidae) inhabiting maize and non-maize growing areas of South Africa. Afr J Herpet 54(1):69–76CrossRefGoogle Scholar
- Zaccanti F, di Grande F, Pasquini CP (1969) Effeti del testosterone sulle gonadi e sugli organi di Bidder in esemplari postmetamorfici di Bufo bufo. Academic Nazionale del Lincei Series 8 46:106–110Google Scholar