A study on the effects of methylmercury in a group of birds, the ibis white, showed that males exposed to this element had more relationships with individuals of the same sex, the less offspring born in the colony studied.
Mercury is one of the most toxics elements. The European Union will ban its use and sale on March 2011, since different studies have shown harmful effects on human and animal health.
A new research by scientists at the University of Florida (USA) and Peradeniya (Sri Lanka) holds that the mercury not only affects the health of animals but can also affect the sexual behavior of some birds. The study, published this week in Proceedings of the Royal Society B (PNAS), was conducted on samples of white ibis (Eudocimus albus) from southern Florida, a wading bird that has about half a meter tall.
Males exposed to mercury in their diet, even with low doses, have prefered to have sex with other animals of the same sex, instead of females. The consequence is the birth of fewer offspring in this colony. Specifically, the laying of eggs was reduced by 30%. According to Peter Frederick Nilmini Jayasena and the authors of this research, this is the first time it shows that a toxic agent can change the sexual preferences of an animal. So far, other studies had found that certain chemicals could "feminize" males or reduce their fertility, but they prefered females when mating.
The experiment was conducted over three years with about 200 white ibis in Florida newborns who were divided into four groups in a circular enclosure with 1200 square meters. This is a species accustomed to living in the community that the provision of the birds was an attempt to replicate their natural habitat to encourage breeding.
Three groups were fed diets containing different doses of methylmercury (MeHg), a toxic compound that concentrates in the body and the food chain. Foods containing mercury were administered when the birds reached 90 days. The fourth group was not exposed to this toxic substance.
Scientists have proven that the three groups who consumed methylmercury had homosexual behavior much more often than the birds that were not exposed to this element. The highest percentage of relationships with individuals of the same sex (55%) occurred in the group that consumed a higher dose. The research warns that methylmercury contamination can reduce the population of these animals.
The authors believe that other birds likely to react similarly to the white ibis, but do not believe that these effects may occur in other animal species. According explained to the magazine New Scientist, have conducted several studies on long-term effects on humans, and none of them found evidence that mercury can affect the sexual behavior of people.
* http://naturlink.sapo.pt/article.aspx?menuid=20&cid=27694&bl=1 *
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