Pollution is disrupting these fish and their genitals

by Nicholas Tufnell

Grey mullet fish have been caught exhibiting female gonads

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The gonads of thick-lipped grey mullets are becoming increasingly feminised in the estuaries of Spain's Basque Country, according to research carried out by members of the Cell Biology in Environmental Toxicology group from the University of the Basque Country. The cause of this feminisation is thought to be due to certain pollutants, which are increasing oestrogen levels in the fish.
The specimens tested came from six zones: Arriluze and Gernika in 2007 and 2008, and since then, Santurtzi, Plentzia, Ondarroa, Deba and Pasaia. Feminised gonads aren't the mullet's only problem -- the acquisition of feminine features has also been detected in various molecular markers.
According to the director of the research group, Miren P. Cajaraville, the results show that "endocrine disruption is a phenomenon that has spread all over our estuaries, which means that, as has been detected in other countries, we have a problem with pollutants".
The source of these pollutants can be found in products many of us use every day, including contraceptive pills, perfumes, detergents and pesticides. The chemicals inside these products react with the fish, causing endocrine disruption, which can throw some fish hormones into disarray. There is very little known about the full effect of these pollutants as they have only recently appeared in the ecosystem.
According to Cajaraville, "our discoveries are significant, because they enable us to know how far these pollutants have spread in our estuaries and rivers and what effects they have; that way, we will be able to adopt methods to prevent them reaching our waters, like legal regulations governing their use."
The pollutants, it is thought, have started to appear in these estuaries as a result of industrial farming and through cleaning systems in wastewater treatment plants. "Our main hypothesis," says Cajaraville of the Urdaibai Biosphere Reserve, "is that they come from the water treatment plant. It was the first place we studied, and continues to be, by far, responsible for the highest percentage of recently appearing pollutants."
 The results of the research have been published in two papers, one in the journal of Science of the Total Environment and the other in the journal of Marine Environmental Research.
Source:  http://www.wired.co.uk