SF Bay Area Koi Club

Organization of Pond and Koi Keepers




Fish becoming Transgender due to chemicals in the environment.

11/07/2017 7:04 AM | Anonymous member (Administrator)

 


While we may have control over the amount of water we put into our ponds, we don't have control of what's IN that water.  Turns out that many water supplies have been inundated with chemicals from sewage treatment plants.  Wells are also a problem, as chemicals leach into ground water supplies.  This article is about a study that concluded that 1/5th of male fish were transgender or hermaphrodites. A fifth of male fish are now transgender because of chemicals from the contraceptive pill being flushed down household drains, a study by Professor Charles Tyler, of the University of Exeter, has suggested.


Male river fish are displaying feminised traits and even producing eggs, the study found. Some have reduced sperm quality and display less aggressive and competitive behaviour, which makes them less likely to breed successfully.  The chemicals causing these effects include ingredients in the contraceptive pill, by-products of cleaning agents, plastics and cosmetics, according to the findings. "Many other chemicals that are discharged through sewage treatment works can affect fish, including antidepressant drugs that reduce the natural shyness of some fish species"  says Professor Charles Tyler.


Professor Tyler presented his findings in a key-note lecture at a symposium where he explained that the offspring of such "transgender" or "intersex" fish can also be more sensitive to the effects of these chemicals in subsequent exposures. Tyler said: "We are showing that some of these chemicals can have much wider health effects on fish that we expected.  "Using specially created transgenic fish that allow us to see responses to these chemicals in the bodies of fish in real time, for example, we have shown that oestrogens found in some plastics affect the valves in the heart." Tests showed 20 per cent of male freshwater fish, such as roach, at 50 sites had feminine characteristics.


More than 200 chemicals from sewage plants have been identified with oestrogen-like effects and drugs such as antidepressants are also altering fish's natural behaviour, his study found.  Professor Tyler said, "Other research has shown that many other chemicals that are discharged through sewage treatment works can affect fish, including antidepressant drugs that reduce the natural shyness of some fish species, including the way they react to predators,"  Professor Tyler will presented his findings in the opening lecture of the 50th Anniversary Symposium of the Fisheries Society in the British Isles at Exeter University this last July 2017.


Dr Steve Simpson, who organised the symposium, said the week of talks would gave "fish biologists from around the world a chance to exchange ideas and discuss how to protect dwindling fish populations in rapidly changing seas and rivers, before it is too late.”  Other research discussed at the event includes how the destruction of coral reefs and their distinctive sounds means fish are getting lost in the water, how fish are shrinking because of climate change and how power cables can disrupt how fish find sexual partners.


From: www.Telegraph.co.uk (link is external) by Sophie Jameson, July 2, 2017


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