[Pharmwaste] Hermaphrodite Frogs Found in Suburban Ponds

Tenace, Laurie Laurie.Tenace at dep.state.fl.us
Tue Apr 8 09:28:08 EDT 2008


http://www.nytimes.com/2008/04/08/science/08frog.html?_r=1&oref=slogin


Hermaphrodite Frogs Found in Suburban Ponds 

By FELICITY BARRINGER
Published: April 8, 2008
Just as frogs' mating season arrives, a study by a Yale professor raises a
troubling issue. How many frogs will be clear on their role in the annual
springtime ritual?
 
Common frogs that make their homes in suburban areas are more likely than
their rural counterparts to develop the reproductive abnormalities previously
found in fish in the Potomac and Mississippi Rivers, according to the study
by David Skelly, a professor of ecology at the Yale School of Forestry and
Environmental Studies.

Dr. Skelly's research found that 21 percent of male green frogs, Rana
clamitans, taken from suburban Connecticut ponds are hermaphrodites, with
immature eggs growing in their testes.

The study is the latest in a decade's worth of research that has found
intersex characteristics in water-dwelling species like sharp-tooth catfish
in South Africa, small-mouth bass on the Potomac and shovelnose sturgeon in
the Mississippi. 

Previous studies, particularly those by scientists at the University of
California, Berkeley, and in the West Virginia office of the United States
Geological Survey, suggested a strong link between the abnormalities and
agriculture, as well as a possible link to atrazine, a common herbicide. But
the Yale study found that intersex frogs were more concentrated in suburban
and urban areas.

Dr. Skelly's study, presented at a seminar at the University of Connecticut,
is being submitted for publication. He looked at a common amphibian, the
green frog, what he called the "Look, Mom, I found a frog" frog. He analyzed
the landscapes within the Connecticut River Valley, where abnormalities were
more likely to be found.

In 2006, a Geological Survey study of small-mouth bass in the Upper Potomac
Basin found that male fish from the most densely inhabited and farmed sites
had the greatest likelihood of having immature eggs in the testes. This year,
scientists from the agency identified chemicals present in the effluent
discharged in the areas where the abnormalities were found. 

"Looking upstream and downstream from wastewater-treatment plants, we see
there's obviously been an impact by some of the chemicals discharged in the
wastewater," said Vicki S. Blazer, an author of the Geological Survey study.
"Things like pesticides, herbicides and flame retardants."

She added that although the Potomac Basin study did not measure high levels
of estrogen in the water, either from pharmaceutical waste or other sources,
"that's certainly a concern." 

The research was in part drawn up to identify endocrine disruptors, or
compounds that can interfere with reproductive hormones.

It focused on specific chemicals, including atrazine, a herbicide used in
agriculture and on suburban lawns and gardens, and chemicals used to give
fragrance to soap and cosmetics. 

The latest Geological Survey study, while suggesting possible links, did not
directly correlate the prevalence of intersex fish and the presence of these
chemicals in wastewater, Dr. Blazer said. The effects of those chemicals
remain unclear. 

A study in 2002 led by Tyrone B. Hayes at Berkeley found that leopard frogs
exposed to atrazine in the laboratory had retarded testicular development
and, in some cases, immature eggs in the testes. 

Atrazine, manufactured by Syngenta of Basel, Switzerland, had the
Environmental Protection Agency renew its approval in 2003. At the request of
the agency, Syngenta has been studying atrazine levels in some watersheds.
The European Union has banned it. 

The environmental agency and the company have been criticized by
environmental groups that contend atrazine is harmful to fish and amphibians
and may have consequences for other species. The company says the chemical is
safe.

Asked what might have caused the reproductive changes found in the new Yale
study, Dr. Skelly said, "I don't know." 

He noted that many suburban areas in his survey used septic systems and that
there had been scant investigation of the chemicals or pharmaceutical residue
in them or the likelihood of leaching into streams or ponds. Suburban areas
are also associated with using herbicides and pesticides.

In contrast to the Geological Survey study, which implicated agricultural
runoff, the frog study found that the more agricultural an area, the lower
the rate of abnormalities. 

In an interview, Dr. Skelly said of the intersex phenomenon: "This is the
first evidence that I think anyone has provided that agriculture is doing
anything but pushing those rates higher. I wouldn't say it's definitive by
any means, but it's certainly not part of the choir.

"I wouldn't want to go out and tell the world that converting landscapes to
agriculture is going to prevent us from facing risks from agricultural
contaminants. What we found in most of the agricultural ponds we sampled was
no evidence of reproductive deformity." 

Dr. Skelly divided his survey into undeveloped, agricultural, suburban and
rural components, based on frogs collected from 23 ponds. That was out of
6,000 ponds surveyed and 136 visited in the Connecticut River Valley. 

Of the 233 frogs whose reproductive organs were analyzed, 13 percent had
abnormalities. 

In urban areas, 18 percent of the collected frogs were intersex; in suburban
areas 21 percent. Just 7 percent of the frogs from agricultural areas were
intersex.

The more suburban the land cover, Dr. Skelly said, the more likely were
abnormalities. Frogs from undeveloped, often forested areas showed no
intersex traits.

The question of the reproductive health of intersex fish is one that Dr.
Blazer said she returned to in a follow-up to her 2006 study. 

"We know the intersex males produce sperm," she said. "The question is
whether the sperm is as good" as the sperm of normal males. 

So far, she said, the sperm of the intersex males has shown some decrease in
the ability for self-propulsion, but the males remain able to reproduce.

Laurie J. Tenace
Environmental Specialist
Florida Department of Environmental Protection
2600 Blair Stone Road, MS 4555
Tallahassee, Florida 32399-2400
PH: (850) 245-8759
FAX: (850) 245-8811
Laurie.Tenace at dep.state.fl.us 

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