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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><b><span style="font-size:24.0pt;font-family:"Times New Roman",serif">Climate change can skew fish gender ratios.
<o:p></o:p></span></b></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:12.0pt;font-family:"Times New Roman",serif">http://www.dailyclimate.org/tdc-newsroom/2015/03/Climate-change-can-skew-fish-gender-ratios<o:p></o:p></span></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:12.0pt;font-family:"Times New Roman",serif">March 10, 2015<o:p></o:p></span></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;margin-bottom:13.5pt"><b><span style="font-size:13.5pt;font-family:"Times New Roman",serif">Scientists find that zebrafish exposed to hormone-disrupting chemical pollution produce abnormal numbers of male
offspring, especially in increasingly warmer water.<o:p></o:p></span></b></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><b><span style="font-size:12.0pt;font-family:"Times New Roman",serif">By Tim Radford<br>
</span></b><span style="font-size:12.0pt;font-family:"Times New Roman",serif">Climate News Network<o:p></o:p></span></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:12.0pt;font-family:"Times New Roman",serif">LONDON – Climate change seems to make everything worse – at least for some wild creatures. British scientists
have just confirmed that higher temperatures could <a href="http://www.eurekalert.org/emb_releases/2015-03/uoe-hdc022615.php"><span style="color:blue">amplify the impact of hormone-disrupting chemicals</span></a> that already pollute the environment.<o:p></o:p></span></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:12.0pt;font-family:"Times New Roman",serif">The world’s waterways are full of industrial pollutants with potentially damaging effects. They include industrial
agents, the waste products of birth-control pills, herbicides, pharmaceuticals and even the residues of illegal narcotics. Altogether, more than 800 chemicals have been identified as having some hormone-disrupting capacity.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Times New Roman",serif">The world's waterways are full of industrial pollutants with potentially damaging effects.<o:p></o:p></span></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:12.0pt;font-family:"Times New Roman",serif">Ross Brown, then with AstraZeneca Research and now at the University of Exeter, and colleagues report in the
<a href="http://www.pnas.org/cgi/doi/10.1073/pnas.1416269112"><span style="color:blue">Proceedings of the National Academy of Sciences</span></a> that they decided to look at the long-term effects of clotrimazole, a chemical commonly used in antifungal treatments
and believed to disrupt hormones and interfere with the sex ratios of fish and amphibians.<o:p></o:p></span></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:12.0pt;font-family:"Times New Roman",serif">Conservationists – and others – have worried for decades about the build-up of such chemicals in the environment.
They have cited them as possible threats to biodiversity, and have produced evidence that they could be implicated in sexual abnormalities in some species.<o:p></o:p></span></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><b><span style="font-size:13.5pt;font-family:"Times New Roman",serif">Extinction risk<o:p></o:p></span></b></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:12.0pt;font-family:"Times New Roman",serif">But these have been regarded as a separate problem, and not part of the mix of stresses that could accompany climate
change.<o:p></o:p></span></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:12.0pt;font-family:"Times New Roman",serif">The British scientists tested a well-established laboratory and aquarium favorite, the zebrafish (Danio rerio).
This is the first fish to have its entire genome sequenced – which means researchers already know a great deal about its life cycle, physiology and development.<o:p></o:p></span></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:12.0pt;font-family:"Times New Roman",serif">So the scientists observed normal spawning at the temperatures in which the fish evolved, and five degrees higher,
at the 33°C projected for its home waters in 2100.<o:p></o:p></span></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:12.0pt;font-family:"Times New Roman",serif">In the tests, the water level of endocrine-disrupting clotrimazole was also at levels found polluting the world’s
waterways today.<o:p></o:p></span></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:12.0pt;font-family:"Times New Roman",serif">Temperature plays a powerful role in determining the sex of some as yet unborn members of certain species. Warmer
temperatures can make female status more likely for crocodilians, some lizards and turtles and tortoises. Higher temperatures, however, are likely to encourage higher ratios of male lizards, fish and amphibians.<o:p></o:p></span></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:12.0pt;font-family:"Times New Roman",serif">Since, in normal conditions, temperatures vary around an average, the numbers of males and females in a population
tend to even out. But in reproduction, it’s the females that matter more. So a sustained tilt towards maleness could threaten a population’s survival.<o:p></o:p></span></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><b><span style="font-size:13.5pt;font-family:"Times New Roman",serif">Double jeopardy<o:p></o:p></span></b></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:12.0pt;font-family:"Times New Roman",serif">The researchers found that the zebrafish exposed to the chemical pollutant produced an abnormally high percentage
of male offspring. This ratio got even higher when the fish were confronted with the double whammy of clotrimazole and warmer waters.<o:p></o:p></span></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:12.0pt;font-family:"Times New Roman",serif">Fish that were inbred were the most likely to respond, while fish from a genetically-diverse heritage were somewhat
less affected.<o:p></o:p></span></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:12.0pt;font-family:"Times New Roman",serif">The implication is that endangered species living in small populations in isolated waters could be at greater
risk of extinction.<o:p></o:p></span></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:12.0pt;font-family:"Times New Roman",serif">This was a controlled laboratory experiment, conducted under very precisely-measured conditions, on one well-studied
species.<o:p></o:p></span></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:12.0pt;font-family:"Times New Roman",serif">The real world is a messier place, and outcomes 80 years on for other freshwater fish and amphibians exposed to
an unpredictable suite of stresses are harder to predict.<o:p></o:p></span></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:12.0pt;font-family:"Times New Roman",serif">But the zebrafish, a native of the Indian subcontinent and often a citizen of the flooded rice paddies, is also
likely to experience a wide range of chemical pollutants. So conditions in the wild could be even worse.<o:p></o:p></span></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:12.0pt;font-family:"Times New Roman",serif">“Chemicals in the environment are usually looked at in isolation, but in reality animals are exposed to multiple
stressful events at the same time,” says the report’s senior author, bioscientist Charles Tyler, of the University of Exeter. “They include changes in temperature, food scarcity, or harmful chemicals.<o:p></o:p></span></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:12.0pt;font-family:"Times New Roman",serif">“It is important that we understand how these pressures interact if we are to understand the real impact of rising
global temperatures and increasing levels of pollution.”<o:p></o:p></span></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Laurie Tenace<o:p></o:p></p>
<p class="MsoNormal">Environmental Specialist<o:p></o:p></p>
<p class="MsoNormal">Waste Reduction Section<o:p></o:p></p>
<p class="MsoNormal">Florida Department of Environmental Protection<o:p></o:p></p>
<p class="MsoNormal">2600 Blair Stone Road, MS 4555<o:p></o:p></p>
<p class="MsoNormal">Tallahassee, FL 32399-2400<o:p></o:p></p>
<p class="MsoNormal">850.245.8759<o:p></o:p></p>
<p class="MsoNormal">Laurie.Tenace@dep.state.fl.us<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
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