Sewage Effluent Affects Fish
Effluent changes gender of fish
In 2004, David Norris reported
that fish just below the Boulder, Colo., Wastewater Treatment Plant's
outflow pipe were changing sex.
Two years later, the University of Colorado
integrative physiology professor has expanded his study, which now
involves one "Fish Exposure Mobile" research trailer in operation and a
second on the way.
Science done in the trailer has verified
Norris' 2004 study and shown that surprisingly low concentrations of
treatment-plant effluent can change male fish into females.
The 2004 study showed
that certain chemicals from pharmaceuticals and personal-care products
made it through the Boulder Wastewater Treatment Plant and into Boulder
Creek. Ninety percent of the white suckers swimming downstream of the
plant were female. Upstream, there was an even split.
"What we see in the fish
downstream is as if they are taking birth control pills," Norris said.
The female fish -- both the transsexuals and
the original girls -- had smaller-than-average ovaries. The remaining
males produced less sperm, showing the water effluent also has
contraceptive effects, he said.
The chemicals are believed to come from
excreted birth-control hormones, natural female hormones and detergents
flushed down toilets and drains. In the ecosystem, they are known as
endocrine disrupters, settling into cell receptors intended for hormones
and garbling the body's chemical communications.
To bolster his evidence, in 2005 Norris and
colleague Alan Vajda, a CU research associate, set up the Fish Exposure
Mobile in a trailer borrowed from the Colorado Division of Wildlife.
U.S. Geological Survey scientists Larry Barber and James Gray also are
working with Norris' team, and the city of Boulder's cooperation also
has been vital, the scientists say.
Where Norris and Vajda are what Barber called
"world-class endocrinologists," Barber and Gray are chemists who have
advanced detection techniques to the point they can spot human estrogen
in concentrations as low as 0.2 parts per trillion.
They needed such exactitude because human
estrogen, or 17 beta estradiol, affects fish at concentrations as low as
one part per trillion - the equivalent of a pinch of salt in an Olympic
pool, Norris said.
Barber said volumes of human estrogen in the
pure treatment-plant effluent range from one part per trillion to about
10 parts per trillion.
The Fish Exposure Mobile, parked next to the
creek on sewage treatment plant property, pulls water directly from the
plant's outflow pipe and can dilute it using precise volumes of upstream
Boulder Creek water.
Fathead minnows swim in two identical tanks
inside, each 200 gallons. One fills with upstream creek water; the other
with varying degrees of wastewater plant effluent. Such control lets
researchers see how fish react to varying effluent concentrations.
They aimed to create a controlled experiment
and confirm if estrogen and other compounds from the treatment plant
were responsible for the fish sex change.
"The males were feminized in seven days,"
Norris said. "You don't need a Ph.D. to sex them."
The males have bumps on the forehead and
often attack each other. The fish exposed to the effluent water lost
their bumps and acted like girls. It confirmed effluent to be the
culprit.
Diluting the treatment plant's effluent 50
percent feminized breeding male fish in a week to 15 days, Norris said.
Some of the effects remained evident even when the wastewater plant
effluent was diluted 75 percent.
"We were excited to get these results, but at
the same time we're a little bit appalled at what we've seen," Norris
said.
Sheila Murphy, a hydrologist with the U.S.
Geological Survey in Boulder, said the Fish Exposure Mobile work has
been important to counter skeptics who attribute transsexual fish in the
Potomac River and other waterways to temperature changes or other
environmental influences.
"What it's showing is
that it's indeed from the wastewater plant," Murphy said.
***
Return to the Resource Library
"What's in YOUR Water?"
James P
McMahon
Ecologist
To view my experience and credentials:
©
Sweetwater, LLC
Return to:
* * *