by Nicholas Tufnell
Grey mullet fish have been caught exhibiting female gonads
Shutterstock
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