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Agriculture Alters Gonadal Form and Function in the Toad Bufo marinus
BACKGROUND: Many agricultural contaminants disrupt endocrine systems of wildlife. However, evidence of endocrine disruption in wild amphibians living in agricultural areas has been controversial. Typically, studies on the effects of pollutants on wildlife attempt to compare polluted with unpolluted...
Autores principales: | , , , , , |
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Formato: | Texto |
Lenguaje: | English |
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National Institute of Environmental Health Sciences
2008
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Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2592273/ https://www.ncbi.nlm.nih.gov/pubmed/19057706 http://dx.doi.org/10.1289/ehp.11536 |
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author | McCoy, Krista A. Bortnick, Lauriel J. Campbell, Chelsey M. Hamlin, Heather J. Guillette, Louis J. St. Mary, Colette M. |
author_facet | McCoy, Krista A. Bortnick, Lauriel J. Campbell, Chelsey M. Hamlin, Heather J. Guillette, Louis J. St. Mary, Colette M. |
author_sort | McCoy, Krista A. |
collection | PubMed |
description | BACKGROUND: Many agricultural contaminants disrupt endocrine systems of wildlife. However, evidence of endocrine disruption in wild amphibians living in agricultural areas has been controversial. Typically, studies on the effects of pollutants on wildlife attempt to compare polluted with unpolluted sites. OBJECTIVES: We took a novel approach to address this question by explicitly quantifying the relationship between gonadal abnormalities and habitats characterized by differing degrees of agricultural activity. METHODS: We quantified the occurrence of gonadal abnormalities and measures of gonadal function in at least 20 giant toads (Bufo marinus) from each of five sites that occur along a gradient of increasing agricultural land use from 0 to 97%. RESULTS: The number of abnormalities and frequency of intersex gonads increased with agriculture in a dose-dependent fashion. These gonadal abnormalities were associated with altered gonadal function. Testosterone, but not 17β-estradiol, concentrations were altered and secondary sexual traits were either feminized (increased skin mottling) or demasculinized (reduced forearm width and nuptial pad number) in intersex toads. Based on the end points we examined, female morphology and physiology did not differ across sites. However, males from agricultural areas had hormone concentrations and secondary sexual traits that were intermediate between intersex toads and non-agricultural male toads. Skin coloration at the most agricultural site was not sexually dimorphic; males had female coloration. CONCLUSIONS: Steroid hormone concentrations and secondary sexual traits correlate with reproductive activity and success, so affected toads likely have reduced reproductive success. These reproductive abnormalities could certainly contribute to amphibian population declines occurring in areas exposed to agricultural contaminants. |
format | Text |
id | pubmed-2592273 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2008 |
publisher | National Institute of Environmental Health Sciences |
record_format | MEDLINE/PubMed |
spelling | pubmed-25922732008-12-04 Agriculture Alters Gonadal Form and Function in the Toad Bufo marinus McCoy, Krista A. Bortnick, Lauriel J. Campbell, Chelsey M. Hamlin, Heather J. Guillette, Louis J. St. Mary, Colette M. Environ Health Perspect Research BACKGROUND: Many agricultural contaminants disrupt endocrine systems of wildlife. However, evidence of endocrine disruption in wild amphibians living in agricultural areas has been controversial. Typically, studies on the effects of pollutants on wildlife attempt to compare polluted with unpolluted sites. OBJECTIVES: We took a novel approach to address this question by explicitly quantifying the relationship between gonadal abnormalities and habitats characterized by differing degrees of agricultural activity. METHODS: We quantified the occurrence of gonadal abnormalities and measures of gonadal function in at least 20 giant toads (Bufo marinus) from each of five sites that occur along a gradient of increasing agricultural land use from 0 to 97%. RESULTS: The number of abnormalities and frequency of intersex gonads increased with agriculture in a dose-dependent fashion. These gonadal abnormalities were associated with altered gonadal function. Testosterone, but not 17β-estradiol, concentrations were altered and secondary sexual traits were either feminized (increased skin mottling) or demasculinized (reduced forearm width and nuptial pad number) in intersex toads. Based on the end points we examined, female morphology and physiology did not differ across sites. However, males from agricultural areas had hormone concentrations and secondary sexual traits that were intermediate between intersex toads and non-agricultural male toads. Skin coloration at the most agricultural site was not sexually dimorphic; males had female coloration. CONCLUSIONS: Steroid hormone concentrations and secondary sexual traits correlate with reproductive activity and success, so affected toads likely have reduced reproductive success. These reproductive abnormalities could certainly contribute to amphibian population declines occurring in areas exposed to agricultural contaminants. National Institute of Environmental Health Sciences 2008-11 2008-07-03 /pmc/articles/PMC2592273/ /pubmed/19057706 http://dx.doi.org/10.1289/ehp.11536 Text en http://creativecommons.org/publicdomain/mark/1.0/ Publication of EHP lies in the public domain and is therefore without copyright. All text from EHP may be reprinted freely. Use of materials published in EHP should be acknowledged (for example, ?Reproduced with permission from Environmental Health Perspectives?); pertinent reference information should be provided for the article from which the material was reproduced. Articles from EHP, especially the News section, may contain photographs or illustrations copyrighted by other commercial organizations or individuals that may not be used without obtaining prior approval from the holder of the copyright. |
spellingShingle | Research McCoy, Krista A. Bortnick, Lauriel J. Campbell, Chelsey M. Hamlin, Heather J. Guillette, Louis J. St. Mary, Colette M. Agriculture Alters Gonadal Form and Function in the Toad Bufo marinus |
title | Agriculture Alters Gonadal Form and Function in the Toad Bufo marinus |
title_full | Agriculture Alters Gonadal Form and Function in the Toad Bufo marinus |
title_fullStr | Agriculture Alters Gonadal Form and Function in the Toad Bufo marinus |
title_full_unstemmed | Agriculture Alters Gonadal Form and Function in the Toad Bufo marinus |
title_short | Agriculture Alters Gonadal Form and Function in the Toad Bufo marinus |
title_sort | agriculture alters gonadal form and function in the toad bufo marinus |
topic | Research |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2592273/ https://www.ncbi.nlm.nih.gov/pubmed/19057706 http://dx.doi.org/10.1289/ehp.11536 |
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