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Wild intersex roach (Rutilus rutilus) have reduced fertility
Susan Jobling1, S Coey, J G Whitmore
1Department of Biological Sciences, Brunel University, Kingston Lane, Uxbridge, Middlesex UB8 3PH, UK. susan.jobling@brunel.ac.uk
Biology of Reproduction
|July 24, 2002
Summary
Endocrine disruptors harm fish reproduction, causing reduced sperm quality and fertilization success in intersex roach. This study provides the first evidence linking intersex conditions to impaired reproductive capabilities in wild vertebrates.
Area of Science:
- Environmental Science
- Reproductive Biology
- Ecotoxicology
Background:
- Endocrine-disrupting chemicals (EDCs) are environmental contaminants with potential to disrupt reproductive health in wildlife and humans.
- While intersex conditions are reported in fish, direct evidence linking this to reproductive success is limited.
Purpose of the Study:
- To assess gamete quality in wild intersex roach (Rutilus rutilus).
- To determine the impact of intersexuality on sperm characteristics, fertilization success, and offspring viability.
Main Methods:
- Assessed sperm characteristics (motility, density) in intersex and normal male roach.
- Evaluated fertilization success and offspring viability from intersex and normal male gametes.
- Correlated the degree of feminization with male gamete quality metrics.
Main Results:
- Intersex roach exhibited significantly reduced milt production compared to normal males.
- Sperm motility, fertilization success, and viable offspring production were lower in intersex fish.
- Male gamete quality negatively correlated with the degree of feminization, with severe cases showing up to 75% reduction in fertilization success.
Conclusions:
- This study provides the first evidence linking morphological effects of endocrine disruption (intersex) to reproductive capability in wild vertebrates.
- Reduced gamete quality in intersex roach indicates a threat to male reproductive health from environmental EDC mixtures.
- EDCs in aquatic environments may pose a significant risk to fish populations by impairing male fertility.