Discovered bisexual frogs in the suburbs

By FELICITY BARRINGER

The study was conducted by a Yale University professor as soon as the frog mating season came up with a controversial issue. How many frogs know its role in this spring's annual event?

According to a study conducted by ecology professor David Skelly of the Yale University of Forestry and Environmental Studies, frogs living in the suburbs tend to develop more unusual forms of reproduction than those of the live in rural areas. This phenomenon was previously discovered in the river fish Potomac and Mississippi.

Dr. Skelly's research shows that 21% of male green frogs Rnan clamitans taken from suburban ponds in Connecticut are bisexual, their testicles have growing eggs.

This is the latest study in the past decade and it has found a multi-gender feature in aquatic animals such as sharp-toothed catfish in South Africa, small-mouth bass in Potomac River and shovel-nosed fish. Mississippi River.

Images of young eggs in frog testicles (Photo: Susan Bolden)

Some previous studies, particularly those of scientists at the University of California, Berkeley, and the West Virginia office of the US Geological Survey, have shown a strong connection between characteristics unusual and agricultural, as well as a link to herbicides atrazine. However, Yale University research has shown that multidisciplinary frogs are concentrated mainly in suburban and urban areas.

Dr. Skelly's research is presented at the University of Connecticut conference, which is being widely published. He explores a common amphibian, green frog. He analyzed the habitat around the Connecticut River valley, where other features were easily found.

In 2006, a geological survey of small mouth bass in the upper Potomac River found male fish in densely populated areas and many farms have the highest likelihood of unripe eggs in the testes. This year, scientists have identified chemical substances pouring into tributary rivers in the area with unusual changes in animals.

Vicki S. Blazer, author of the geological survey, said: 'Looking upstream and downstream from the wastewater treatment area, we can clearly see the impact of some chemicals in wastewater. Substances such as pesticides, herbicides or flame retardants. ' Although the Potomac basin study does not measure high estrogen levels in water, from medical waste or any other source, 'this is clearly a concern,' she said.

The study is partially planned to determine the type of endocrine disruptor, or compound that affects the reproductive hormone.

The study focused on certain chemicals, including atrazine - an agricultural herbicide, in lawns and suburban gardens - besides the chemicals used to Aroma for soap or cosmetics.

Dr. Blazer said, the most recent geological survey, although showing the link but does not directly raise the prevalence of multi-sex fishes and the presence of chemicals in wastewater . The impact of those chemicals is still unknown.

A 2002 study, directed by Tyrone B. Hayes of Berkeley, discovered that a frog frog when exposed to atrazine in the laboratory slowed testicular development, and in some cases formed an egg. Unripe in complete news.

Atrazine, produced by Syngenta in Basel - Switzerland, was certified by the Environmental Protection Agency in 2003, but at the request of the organization, Syngenta studied atrazine concentrations in some river basins. The European Union has banned the production and use of this product.

The environmental agency and the above-mentioned enterprise have been criticized by environmental organizations for atrazine being harmful to fish and amphibians; It may leave some consequences for other species. Meanwhile Syngenta said that this chemical is harmless.

A Connecticut green frog (left) and an agricultural pond in Yale University research.The study compared frogs from different regions, from undeveloped areas to suburbs.(Photo: Tracy Langkilde, Susan Bolden)

When asked what could be the cause of the reproductive changes found in Yale's new study, Dr. Skelly answered: ' I don't know '.

He stressed that many suburbs in his investigation used a system of infections, in addition to very few investigations on chemicals or medical waste, or they could have been detected in streams or ponds in these areas. The suburbs also involve the use of pesticides and herbicides.

In contrast to the geological survey study, which points to agricultural causes; Research on frogs has demonstrated that the rate of change is often lower than in agricultural areas.

In an interview, Dr. Skelly spoke about the multidisciplinary phenomenon as follows: 'This is the first evidence that agriculture has nothing to do with high rates. I am not saying that this is completely accurate, but agriculture is not one of the main causes. '

'I don't want to tell the world that turning lands into agricultural land will help us avoid the risk of agricultural pollutants. What we find in most agricultural ponds does not provide any evidence of a change in reproductive status. '

Dr. Skelly zoned her investigation into four regions: undeveloped, agricultural, suburban and rural based frogs taken from 23 ponds out of the 6000 ponds surveyed and 136 ponds check in Connecticut river valley.

Of the 233 frogs analyzed for reproductive organs, 13% had unusual changes. In urban areas, 18% of frogs collected are multi-sex; in the suburbs is 21%. Only 7% of frogs in agricultural areas are multi-sex.

Dr. Skelly said, the more suburbs the frog has the unusual ability to change. Frogs in undeveloped areas, often in mountainous areas, have no signs of multi-gender.

The question of reproductive health of multi-sex fish is the question Dr. Blazer said she mentioned while continuing her 2006 study. She said: 'We know that multidisciplinary males still produce sperm, but the question is whether this semen is as good as the sperm of normal humans.' She also said that so far the semen of multi-sex males showed signs of diminishing ejaculation, but they are still fertile.