Can roach, Rutilus rutilus, adapt to the harmful effects of oestrogen exposure from waste water treatment work effluents?
Major worldwide attention has focused on the observations of disruptions of reproduction in both wildlife and human populations that can result from exposure to chemicals that interfere with the body's hormone signalling systems (so-called endocrine disrupting chemicals; EDCs) impacting on reproductive health. We have shown that reproduction in fish (roach, a common member of the carp family of fish) living in many UK Rivers has been damaged by exposure to EDCs contained in the wastewater treatment works (WwTW) effluents and the chemicals responsible for these effects include natural oestrogen hormones and pharmaceutical oestrogens in the contraceptive pill. Feminised roach have a reduced capability to breed under competitive breeding conditions. Nevertheless, we find that in some stretches of these rivers with high oestrogenic exposure roach populations appear to be reproductively self-sustaining. Establishing whether fish (here roach) have adapted to oestrogenic contaminants, how they do this (the mechanisms) and the possible fitness costs of these adaptations are essential in understanding resilience (and thus sustainability) of fish populations living in these polluted environments.
The overall aim of the project is to examine whether exposure of roach populations to oestrogenic WwTW effluents over multiple generations, has resulted in genetic selection and the impacts of selection on the susceptibility in male fish to develop oestrogen-induced effects associated with negative fitness consequences. Specifically this data was generated to construct a transcriptome and subsequently identify genetic differences (single nucleotide polymorphisms -SNPs) in (1) specific (candidate) genes that we know are important in oestrogen signalling of reproductive (and other life) processes and (2) control genes for which there is no evidence for involvement in oestrogen signalling or reproductive processes. These data will then be used to test whether candidate genes have signatures of selection in roach populations confined to rivers with a high proportion of estrogenic effluent.