New research has provided the first evidence that ‘gender bending’ chemicals which find their way from human products into rivers and oceans can have a significant impact on the ability of fish to breed in UK Rivers.
The findings from the four year study, led by the universities of Exeter and Brunel, has important implications for understanding the impacts of these chemicals on ecosystem health and possibly on humans.
Endocrine disrupting chemicals (EDCs) disrupt the ways that hormones work in the bodies of vertebrates (animals with backbones), including humans.
They can be found in everything from female contraceptive drugs and hormone replacement therapy pills, to washing up liquid, with the most well studied EDCs being those that mimic oestrogen (female hormone).
EDCs have been seeping into rivers through the sewage system for decades and have an observed effect on fish, altering male biology to make them more female – hence the ‘gender bending’ reputation of these chemicals.
Until now, there has been no solid evidence to show the long-term impact of this effect on fish in the wild – but the new research focusing on wild roach in two UK rivers (Bourne and Arun) has provided new evidence. Two large-scale breeding studies assessed the ability of fish to breed by using a genetic technique (DNA microsatellites) to match offspring produced to their parents.
It was found that intersex fish – those that had their sexuality compromised by EDCs and which contain both male (sperm) and female (eggs) sex cells – had their reproductive performance reduced by up to 76%.