title: Implications of persistent exposure to treated wastewater effluent for breeding in wild roach (Rutilus rutilus) populations.
abstract: Feminized responses are widespread in wild populations of roach, Rutilus rutilus, living in UK rivers, and some of these responses have been shown to arise as a consequence of exposure to wastewater treatment works (WwTW) effluent discharges and the endocrine disrupting chemicals (EDCs) they contain. The causation of the ovotestis condition in wild roach, however, has yet to be established. Furthermore, the impact of long-term exposure to WwTW effluents on the reproductive fitness of wild fish populations is not known, and this information is crucial for population level effect assessments. We undertook a chronic exposure of roach to a treated estrogenic wastewater effluent for up to 3.5 years to assess principally for effects on subsequent reproductive fitness, as determined through parentage analysis on offspring from a competitive breeding study. In generating the fish for the breeding study we found that exposure to full strength WwTW effluent until sexual maturity resulted in sex reversal in almost all males in the population; 98% of the exposed fish were phenotypic females, containing ovaries. Furthermore, fish exposed to a 50% dilution of WwTW effluent contained ovotestis (21% of the male roach) that was absent from the control population. In competitive breeding studies, and applying DNA microsatellites to assess parentage, we show that presumptive females exposed to sexual maturity to WwTW effluent bred normally, albeit in the absence of nonexposed females, but putative sex-reversed males breeding as females contributed poorly, if at all, in a breeding population, depending on the competition. These novel findings on sex reversal add a new dimension for impact assessments of exposure to WwTW effluents on fish populations.
authors.affiliation: University of Exeter, Biosciences, College of Life & Environmental Sciences, Exeter EX4 4PS, United Kingdom. A.Lange@exeter.ac.uk
authors.forename: Anke
authors.initials: A
authors.lastname: Lange
authors.forename: Gregory C
authors.initials: GC
authors.lastname: Paull
authors.forename: Patrick B
authors.initials: PB
authors.lastname: Hamilton
authors.forename: Taisen
authors.initials: T
authors.lastname: Iguchi
authors.forename: Charles R
authors.initials: CR
authors.lastname: Tyler
mesh_terms: D000818:Animals; D001947:Breeding; D003530:Cyprinidae / Q000502:physiology*; D052244:Endocrine Disruptors / Q000633:toxicity*; D004970:Estrone; D005260:Female; D008297:Male; D010053:Ovary; D045483:Rivers; D012741:Sexual Maturation / Q000187:drug effects*; D062065:Wastewater / Q000633:toxicity*; D014874:Water Pollutants, Chemical / Q000633:toxicity
chemical_list: D052244:Endocrine Disruptors; D004970:Estrone; D062065:Wastewater; D014874:Water Pollutants, Chemical