Thought extinct when marshes were drained in 1950's
November 2011. Two specimens of a frog that was believed to be extinct have been found in Israel. The Hula painted frog (Discoglossus nigriventer) was declared extinct in 1996 by the International Union for Conservation of Nature.
"The species now has another chance to survive," said a representative of Israel's Nature and Parks Authority. An inspector from the Authority found the frog in the Hula Valley and is has now been placed in a protective facility.
Only 5 have ever been found
Only five Hula painted frogs have ever been collected. Four were found in 1940 and one in the 1950s, when most the Hula Valley's marshes were drained to create arable land eradicate malaria. Parts of the valley were re-flooded three years ago, and it is believed that this has helped the frog cling on to existence.
In 2000, a scientist from the Lebanese nature protection organisation A Rocha claimed he had seen a frog species which could be Discoglossus nigriventer in the Aammiq marshes south of the Beqaa Valley in Lebanon. Two French-Lebanese-British expeditions in the years 2004 and 2005 yielded no confirmation as to the further existence of this species. In August 2010, a search organised by the Amphibian Specialist Group of the International Union for Conservation of Nature set out to look for various species of frogs thought to be extinct in the wild, including the Israel painted frog.
1/3 of world's frogs endangered or extinct
Blaming habitat loss and fungal disease, the IUCN believes nearly a third of the world's amphibian species are endangered or extinct.
Conservation International have launched a global search for "lost frogs". the announcement follows an expedition to the remote mountains of southern Haiti last October, led by CI's Amphibian Conservation Specialist Dr. Robin Moore in partnership with Dr. Blair Hedges of Pennsylvania State University.
http://www.wildlifeextra.com/go/news/israel-hula-frog.html
Thursday, 1 December 2011
PCBs Eating Away at Turtles (Via Herp Digest)
PCBs Eating Away at Turtles- Chemicals that have lingered in the environment for decades may be eating away at the bones of turtles and, maybe, us.
By Eily Sohn, Wed Nov 23, 2011 12:59 PM ET
THE GIST
Exposure to PCBs leads to stunted growth and low bone-density in turtles.
Turtle bones grow like human bones do, and enough exposure to PCBs might harm us in similar ways.
PCBs have been long banned but they remain ubiquitous in the environment.
When exposed to certain levels of PCBs, turtles suffer from stunted growth and weak bones, found a new study.
With low bone-density, turtles have a tougher time diving, swimming and chewing their food. And the same is probably true for fish and other wild animals that are exposed to the ubiquitous environmental pollutant.
It's too soon to know what the results mean for people, and our level of exposure is probably much lower than what some turtles experience. But there is reason to believe that the shelled creatures might be sentinels for human health.
"There have been a few published studies done in Nordic countries that correlated individuals who consume a lot of fish with increased incidence of hip fractures," said Dawn Holliday, a physiological ecologist at Westminster College in Fulton, Missouri.
"Turtles make and break bone through a very similar process that mammals and humans do," she added. "If humans were exposed at similar concentrations, it might be relevant."
PCBs, which were once commonly used in pesticides and a wide variety of industrial fluids, have been banned for decades. But with very slow breakdown times, they are still widespread in the environment, particularly in more developed areas.
In fish, birds, minks and other creatures, PCBs have been linked with slower growth rates, particularly in young animals and developing embryos. Studies have also connected exposure to the chemical with tumors in mink jaws and deformed heads in zebrafish. Exposed adult animals tend to suffer from immune system and related problems.
Holliday and colleague Casey Holliday, who is also her husband, had previously found that PCB exposure caused the metabolisms of turtles to slow down, making them sluggish and less able to turn their food into energy.
To see if turtle bones, too, might be at risk from chemical exposure, the researchers collected diamondback terrapin eggs from the wild, hatched them in the lab, and raised them on frozen brine shrimp.
After eight months to ensure the animals were growing normally, the scientists injected some of the turtles with a dose of PCB 126 that was equivalent to what they might encounter in an urban lake or river. Other turtles got a placebo injection.
Six months later, the researchers reported in the journal Aquatic Toxicology, the shells of the PCB-injected group had grown just one millimeter (0.04-inch) in length, compared to 10 mm (0.4 inches) in the uncontaminated turtles.
"It was such a big difference that you could see it," Dawn Holliday said. "You didn't have to get out a ruler to measure them."
The PCB group also had widespread patches of bone that were not mineralized, while the pollution-free turtles had strong, hard bones. Like dioxins and BPA, PCBs seem to interfere with hormone activity, Holliday said.
The chemicals also appear to disrupt cell growth and differentiation, said Don Tillitt, an environmental toxicologist with the United States Geological Survey in Columbia, Missouri.
Linking illnesses and deformations in wild animal with specific chemicals can be extremely difficult to do, Tillit said. Lab studies like this one add important details that can eventually help scientists both solve and prevent environmental mysteries.
"Every time they make progress in better understanding the adverse effects of chemicals like PCBs, and PCBs in particular," he said, "it quite often helps with ecological risk assessments and how we set regulatory limits for cleaning up sites."
The study is also a reminder that animal deaths aren't the only sign that something is wrong in the environment.
"When we see effects like this, we know there are things that are maybe more insidious," Tillit said. "It's a good reminder that we have to be on guard."
By Eily Sohn, Wed Nov 23, 2011 12:59 PM ET
THE GIST
Exposure to PCBs leads to stunted growth and low bone-density in turtles.
Turtle bones grow like human bones do, and enough exposure to PCBs might harm us in similar ways.
PCBs have been long banned but they remain ubiquitous in the environment.
When exposed to certain levels of PCBs, turtles suffer from stunted growth and weak bones, found a new study.
With low bone-density, turtles have a tougher time diving, swimming and chewing their food. And the same is probably true for fish and other wild animals that are exposed to the ubiquitous environmental pollutant.
It's too soon to know what the results mean for people, and our level of exposure is probably much lower than what some turtles experience. But there is reason to believe that the shelled creatures might be sentinels for human health.
"There have been a few published studies done in Nordic countries that correlated individuals who consume a lot of fish with increased incidence of hip fractures," said Dawn Holliday, a physiological ecologist at Westminster College in Fulton, Missouri.
"Turtles make and break bone through a very similar process that mammals and humans do," she added. "If humans were exposed at similar concentrations, it might be relevant."
PCBs, which were once commonly used in pesticides and a wide variety of industrial fluids, have been banned for decades. But with very slow breakdown times, they are still widespread in the environment, particularly in more developed areas.
In fish, birds, minks and other creatures, PCBs have been linked with slower growth rates, particularly in young animals and developing embryos. Studies have also connected exposure to the chemical with tumors in mink jaws and deformed heads in zebrafish. Exposed adult animals tend to suffer from immune system and related problems.
Holliday and colleague Casey Holliday, who is also her husband, had previously found that PCB exposure caused the metabolisms of turtles to slow down, making them sluggish and less able to turn their food into energy.
To see if turtle bones, too, might be at risk from chemical exposure, the researchers collected diamondback terrapin eggs from the wild, hatched them in the lab, and raised them on frozen brine shrimp.
After eight months to ensure the animals were growing normally, the scientists injected some of the turtles with a dose of PCB 126 that was equivalent to what they might encounter in an urban lake or river. Other turtles got a placebo injection.
Six months later, the researchers reported in the journal Aquatic Toxicology, the shells of the PCB-injected group had grown just one millimeter (0.04-inch) in length, compared to 10 mm (0.4 inches) in the uncontaminated turtles.
"It was such a big difference that you could see it," Dawn Holliday said. "You didn't have to get out a ruler to measure them."
The PCB group also had widespread patches of bone that were not mineralized, while the pollution-free turtles had strong, hard bones. Like dioxins and BPA, PCBs seem to interfere with hormone activity, Holliday said.
The chemicals also appear to disrupt cell growth and differentiation, said Don Tillitt, an environmental toxicologist with the United States Geological Survey in Columbia, Missouri.
Linking illnesses and deformations in wild animal with specific chemicals can be extremely difficult to do, Tillit said. Lab studies like this one add important details that can eventually help scientists both solve and prevent environmental mysteries.
"Every time they make progress in better understanding the adverse effects of chemicals like PCBs, and PCBs in particular," he said, "it quite often helps with ecological risk assessments and how we set regulatory limits for cleaning up sites."
The study is also a reminder that animal deaths aren't the only sign that something is wrong in the environment.
"When we see effects like this, we know there are things that are maybe more insidious," Tillit said. "It's a good reminder that we have to be on guard."
Jellyfish may be helping leatherback sea turtles make a comeback (Via Herp Digest)
Jellyfish may be helping leatherback sea turtles make a comeback
Massive blooms of jellyfish are big source of food for endangered turtles
By Ludmilla Lelis, Orlando Sentinel
11:06 p.m. EST, November 25, 2011
It's the annual bane of beachgoers: massive "blooms" of jellyfish. This past summer, when the blooms hit Volusia and Brevard counties, thousands of ocean swimmers felt their sting.
But researchers say the very creatures that are such a nuisance to people could be fueling the comeback of one of Florida's endangered species: the leatherback sea turtle.
The largest of the marine reptiles, leatherbacks used to be rare visitors to Florida shores. But over the past two decades, the number of nests dug at Florida beaches has been increasing. This year's count is 600 nests, one of the highest ever at beaches tracked for long-term trends. Nest counts are the main method of assessing sea-turtle population trends.
This success story of sea-turtle conservation has a possible twist, said Kelly Stewart, a researcher with the National Oceanic and Atmospheric Administration. When jellyfish are abundant, the leatherbacks have a veritable feast, which could help the female turtles reproduce more often.
"Jellyfish, and any gelatinous species, are the preferred food source for leatherback sea turtles," said Stewart, who completed her doctoral thesis at Duke University on these turtle trends. "So, if there are more jellyfish, that may not be good for people, but is good for the leatherbacks."
Jellyfish aren't really fish but gelatinous creatures related to corals. There are more than 1,000 species around the world, and they have a familiar, umbrella-like body and tentacles. Most have the ability to sting their prey, but their main predators, such as leatherback turtles, seem to be immune to the venom.
In recent years, there have been giant blooms around the world, including several cases involving a jellyfish species that is foreign to an area. Cocoa Beach had such a phenomenon over the Memorial Day weekend with an invasion of mauve stingers, a deep ocean jellyfish that is rare in Florida but common in the Mediterranean.
Although there is some evidence that the blooms are increasing in size and frequency, it's difficult to be sure because there aren't a lot of data on the history of blooms, according to a University of Washington study.
Stewart said a connection between more jellyfish and more leatherback nests needs further study but offers a possible explanation for the resurgence of the turtles.
Ranked as an endangered species, leatherbacks are the largest sea turtles and the only ones lacking a hard shell. In the late 1990s, leatherback nest numbers started to climb dramatically, with some Florida beaches seeing annual increases of as much as 16 percent, Stewart said.
Also, the turtle, which historically nested only in South Florida, has been digging nests farther north. Volusia County, for example, rarely saw a leatherback nest 20 years ago but this year had 13, a record. A leatherback turtle that had been tagged with a satellite tracker even dug a nest in North Carolina after digging nests in Florida, Stewart said.
"It is a remarkable increase, and one of the marvels of sea turtles," said Anne Meylan, research administrator with the Florida Fish and Wildlife Conservation Commission. A co-author of Stewart's study, she credits strong efforts to protect nesting beaches and better monitoring.
However, the study found that nests were increasing even in other countries where the protections are weaker. Stewart said she thinks that means the increases relate to what's happening to turtles in the Atlantic as they travel.
That turtles are reaping a benefit from jellyfish feasts would make sense because of the need for females to fatten up to reproduce. Sea turtles typically nest only every few years, building energy reserves during non-nesting seasons. A typical nest contains 100 or so eggs, and turtles often dig two or three nests a season - all of which quickly depletes the reserves, Stewart said.
But if leatherback turtles have plenty of jellyfish to eat, they may be able to fatten up quicker and reproduce more often, she said. "These nesting cycles can be reduced if they don't have a limit on their food supply."
Massive blooms of jellyfish are big source of food for endangered turtles
By Ludmilla Lelis, Orlando Sentinel
11:06 p.m. EST, November 25, 2011
It's the annual bane of beachgoers: massive "blooms" of jellyfish. This past summer, when the blooms hit Volusia and Brevard counties, thousands of ocean swimmers felt their sting.
But researchers say the very creatures that are such a nuisance to people could be fueling the comeback of one of Florida's endangered species: the leatherback sea turtle.
The largest of the marine reptiles, leatherbacks used to be rare visitors to Florida shores. But over the past two decades, the number of nests dug at Florida beaches has been increasing. This year's count is 600 nests, one of the highest ever at beaches tracked for long-term trends. Nest counts are the main method of assessing sea-turtle population trends.
This success story of sea-turtle conservation has a possible twist, said Kelly Stewart, a researcher with the National Oceanic and Atmospheric Administration. When jellyfish are abundant, the leatherbacks have a veritable feast, which could help the female turtles reproduce more often.
"Jellyfish, and any gelatinous species, are the preferred food source for leatherback sea turtles," said Stewart, who completed her doctoral thesis at Duke University on these turtle trends. "So, if there are more jellyfish, that may not be good for people, but is good for the leatherbacks."
Jellyfish aren't really fish but gelatinous creatures related to corals. There are more than 1,000 species around the world, and they have a familiar, umbrella-like body and tentacles. Most have the ability to sting their prey, but their main predators, such as leatherback turtles, seem to be immune to the venom.
In recent years, there have been giant blooms around the world, including several cases involving a jellyfish species that is foreign to an area. Cocoa Beach had such a phenomenon over the Memorial Day weekend with an invasion of mauve stingers, a deep ocean jellyfish that is rare in Florida but common in the Mediterranean.
Although there is some evidence that the blooms are increasing in size and frequency, it's difficult to be sure because there aren't a lot of data on the history of blooms, according to a University of Washington study.
Stewart said a connection between more jellyfish and more leatherback nests needs further study but offers a possible explanation for the resurgence of the turtles.
Ranked as an endangered species, leatherbacks are the largest sea turtles and the only ones lacking a hard shell. In the late 1990s, leatherback nest numbers started to climb dramatically, with some Florida beaches seeing annual increases of as much as 16 percent, Stewart said.
Also, the turtle, which historically nested only in South Florida, has been digging nests farther north. Volusia County, for example, rarely saw a leatherback nest 20 years ago but this year had 13, a record. A leatherback turtle that had been tagged with a satellite tracker even dug a nest in North Carolina after digging nests in Florida, Stewart said.
"It is a remarkable increase, and one of the marvels of sea turtles," said Anne Meylan, research administrator with the Florida Fish and Wildlife Conservation Commission. A co-author of Stewart's study, she credits strong efforts to protect nesting beaches and better monitoring.
However, the study found that nests were increasing even in other countries where the protections are weaker. Stewart said she thinks that means the increases relate to what's happening to turtles in the Atlantic as they travel.
That turtles are reaping a benefit from jellyfish feasts would make sense because of the need for females to fatten up to reproduce. Sea turtles typically nest only every few years, building energy reserves during non-nesting seasons. A typical nest contains 100 or so eggs, and turtles often dig two or three nests a season - all of which quickly depletes the reserves, Stewart said.
But if leatherback turtles have plenty of jellyfish to eat, they may be able to fatten up quicker and reproduce more often, she said. "These nesting cycles can be reduced if they don't have a limit on their food supply."
Bill Nelson's effort to ban interstate python trade (Via Herp Digest)
Bill Nelson's effort to ban interstate python trade concerns Fla. wildlife officials
By Christine Stapleton Palm Beach Post- November 26, 2011
WEST PALM BEACH-
The good intentions of Democratic Sen. Bill Nelson to help control the invasion of Burmese pythons in the Everglades has Florida wildlife officials slightly cringing.
Nelson sent a single-page letter to President Obama on Thursday urging him to speed up the process for including the Burmese python and five other pythons roaming around South Florida on the U.S. Fish & Wildlife Service's list of injurious species. That would trigger a ban on the import and interstate trade of the giant constrictors.
"These dangerous snakes have killed people including an innocent child, devoured endangered species and most recently, a Burmese python consumed a 76-pound adult deer," Nelson wrote in the letter. "Further delay is unacceptable and the consequences could be fatal."
While wildlife officials are all for eradicating the wild snakes, they say the unintended consequences of banning the import and interstate trade could lead to even more of the snakes being dumped in the wild by shady dealers stuck with an inventory of worthless snakes.
"We certainly have a concern, in the event they are put on the injurious list, of what would happen to the inventory of the commercial guys," said Scott Hardin, exotic species coordinator at the Florida Fish and Wildlife Conservation Commission. "We have seen cases when animals go on the injurious list and then all of a sudden you find them in the wrong place."
Last year Florida dealers and breeders lost much of their in-state business when it became illegal to acquire the six species of pythons as pets after the Florida Fish and Wildlife Conservation Commission listed them as a conditional species.
Floridians who already owned pet pythons could keep them, but only reptile dealers, researchers and public exhibitors could apply for a permit to import or possess new pythons.
If pythons are further regulated and placed on the federal injurious species list, commercial dealers and breeders will not be able to sell and ship their snakes to buyers in other states, leaving them to figure out how to dispose of their pythons.
While most dealers are "trying to do the right thing," and would not release their snakes in the wild, "it certainly could happen with some of the marginal dealers," Hardin said.
David Barkasy and his wife, Katie Barkasy, are license dealers who have been selling reptiles for more than 20 years. Although the Barkasys do not breed pythons, they said their business ReptilesToGo.com in Myakka City would take at least a 10 percent hit if they cannot buy, sell and ship pythons out of Florida.
"Nationwide this is going to affect a lot of people," Barkasy said. "It's going to have a big impact."
As for dealers' inventory of pythons, if the injurious designation goes into effect, some will let them go in the wild and others will kill them, Barkasy said.
The FWC has no plans for getting rid of the dealers' unwanted snakes. The fate of the pythons "wouldn't be within our purview necessarily," Hardin said.
However, the commission does host non-native pet amnesty days, which allow pet owners to surrender their non-native amphibians, birds, fish, mammals, invertebrates and reptiles at specific locations throughout the state at no charge and with no penalties.
Since the first pythons were spotted in the wild in Florida in the 1980s, captures, hunting and escapes have grabbed headlines around the world. Although the exact number of pythons in the wild is not known, the U.S. Geological Survey has estimated between 5,000 and 100,000 in the Everglades.
The South Florida Water Management District petitioned the U.S. Fish & Wildlife Service to include the Burmese python as an injurious wildlife species in June 2006. As the district waited for approval, the number of pythons captured rose dramatically, from 170 in 2006 to 367 in 2009.
The district's petition went to the U.S. Fish and Wildlife Service, which held public hearings and developed a draft rule. The draft rule went to the U.S. Office of Management and Budget, where it has sat for nearly nine months.
"In total, the rule-making process has taken almost five years and in that time, over 100,000 more giant constrictor snakes have entered the U.S.," Nelson wrote. "And until these animals are listed as injurious, they will continue to flow into the country unabated."
But the injurious listing could also encourage smuggling and illegal sales.
"A well-regulated trade is preferable to a black market," Hardin said. "We hope we can have conservation with flexibility and that it is equitable."
Are efforts to get rid of the snakes working? Hardin believes freezing temperatures earlier this year killed many snakes.
The more aggressive African Rock python is nearly 95 percent eradicated, he said.
"There are fewer pythons than there were three years ago," Hardin said. "I think we really have gotten better about knowing where to look."
By Christine Stapleton Palm Beach Post- November 26, 2011
WEST PALM BEACH-
The good intentions of Democratic Sen. Bill Nelson to help control the invasion of Burmese pythons in the Everglades has Florida wildlife officials slightly cringing.
Nelson sent a single-page letter to President Obama on Thursday urging him to speed up the process for including the Burmese python and five other pythons roaming around South Florida on the U.S. Fish & Wildlife Service's list of injurious species. That would trigger a ban on the import and interstate trade of the giant constrictors.
"These dangerous snakes have killed people including an innocent child, devoured endangered species and most recently, a Burmese python consumed a 76-pound adult deer," Nelson wrote in the letter. "Further delay is unacceptable and the consequences could be fatal."
While wildlife officials are all for eradicating the wild snakes, they say the unintended consequences of banning the import and interstate trade could lead to even more of the snakes being dumped in the wild by shady dealers stuck with an inventory of worthless snakes.
"We certainly have a concern, in the event they are put on the injurious list, of what would happen to the inventory of the commercial guys," said Scott Hardin, exotic species coordinator at the Florida Fish and Wildlife Conservation Commission. "We have seen cases when animals go on the injurious list and then all of a sudden you find them in the wrong place."
Last year Florida dealers and breeders lost much of their in-state business when it became illegal to acquire the six species of pythons as pets after the Florida Fish and Wildlife Conservation Commission listed them as a conditional species.
Floridians who already owned pet pythons could keep them, but only reptile dealers, researchers and public exhibitors could apply for a permit to import or possess new pythons.
If pythons are further regulated and placed on the federal injurious species list, commercial dealers and breeders will not be able to sell and ship their snakes to buyers in other states, leaving them to figure out how to dispose of their pythons.
While most dealers are "trying to do the right thing," and would not release their snakes in the wild, "it certainly could happen with some of the marginal dealers," Hardin said.
David Barkasy and his wife, Katie Barkasy, are license dealers who have been selling reptiles for more than 20 years. Although the Barkasys do not breed pythons, they said their business ReptilesToGo.com in Myakka City would take at least a 10 percent hit if they cannot buy, sell and ship pythons out of Florida.
"Nationwide this is going to affect a lot of people," Barkasy said. "It's going to have a big impact."
As for dealers' inventory of pythons, if the injurious designation goes into effect, some will let them go in the wild and others will kill them, Barkasy said.
The FWC has no plans for getting rid of the dealers' unwanted snakes. The fate of the pythons "wouldn't be within our purview necessarily," Hardin said.
However, the commission does host non-native pet amnesty days, which allow pet owners to surrender their non-native amphibians, birds, fish, mammals, invertebrates and reptiles at specific locations throughout the state at no charge and with no penalties.
Since the first pythons were spotted in the wild in Florida in the 1980s, captures, hunting and escapes have grabbed headlines around the world. Although the exact number of pythons in the wild is not known, the U.S. Geological Survey has estimated between 5,000 and 100,000 in the Everglades.
The South Florida Water Management District petitioned the U.S. Fish & Wildlife Service to include the Burmese python as an injurious wildlife species in June 2006. As the district waited for approval, the number of pythons captured rose dramatically, from 170 in 2006 to 367 in 2009.
The district's petition went to the U.S. Fish and Wildlife Service, which held public hearings and developed a draft rule. The draft rule went to the U.S. Office of Management and Budget, where it has sat for nearly nine months.
"In total, the rule-making process has taken almost five years and in that time, over 100,000 more giant constrictor snakes have entered the U.S.," Nelson wrote. "And until these animals are listed as injurious, they will continue to flow into the country unabated."
But the injurious listing could also encourage smuggling and illegal sales.
"A well-regulated trade is preferable to a black market," Hardin said. "We hope we can have conservation with flexibility and that it is equitable."
Are efforts to get rid of the snakes working? Hardin believes freezing temperatures earlier this year killed many snakes.
The more aggressive African Rock python is nearly 95 percent eradicated, he said.
"There are fewer pythons than there were three years ago," Hardin said. "I think we really have gotten better about knowing where to look."
Herbicide Atrazine Spurs Reproductive Problems in Many Creatures (Via Herp Digest)
Herbicide Atrazine Spurs Reproductive Problems in Many Creatures, Report Finds
ScienceDaily (Nov. 28, 2011) - An international team of researchers has reviewed the evidence linking exposure to atrazine -- an herbicide widely used in the U.S. and more than 60 other nations -- to reproductive problems in animals. The team found consistent patterns of reproductive dysfunction in amphibians, fish, reptiles and mammals exposed to the chemical.
Atrazine is the second-most widely used herbicide in the U.S. More than 75 million pounds of it are applied to corn and other crops, and it is the most commonly detected pesticide contaminant of groundwater, surface water and rain in the U.S.
The new review, compiled by 22 scientists studying atrazine in North and South America, Europe and Japan, appears in the Journal of Steroid Biochemistry and Molecular Biology.
The researchers looked at studies linking atrazine exposure to abnormal androgen (male hormone) levels in fish, amphibians, reptiles and mammals and studies that found a common association between exposure to the herbicide and the "feminization" of male gonads in many animals.
The most robust findings are in amphibians, said University of Illinois comparative biosciences professor Val Beasley, a co-author of the review. At least 10 studies found that exposure to atrazine feminizes male frogs, sometimes to the point of sex reversal, he said.
Beasley's lab was one of the first to find that male frogs exposed to atrazine in the wild were more likely to have both male and female gonadal tissue than frogs living in an atrazine-free environment. And in a 2010 study, Tyrone Hayes, a professor of integrative biology at the University of California at Berkeley and lead author of the review, reported in the Proceedings of the National Academy of Sciences that atrazine exposure in frogs was associated with "genetic males becoming females and functioning as females," Beasley said.
"And this is not at extremely high concentrations," he said. "These are at concentrations that are found in the environment."
The new review describes the disruptions of hormone function and sexual development reported in studies of mammals, frogs, fish, reptiles and human cells exposed to the herbicide. The studies found that atrazine exposure can change the expression of genes involved in hormone signaling, interfere with metamorphosis, inhibit key enzymes that control estrogen and androgen production, skew the sex ratio of wild and laboratory animals (toward female) and otherwise disrupt the normal reproductive development and functioning of males and females.
"One of the things that became clear in writing this paper is that atrazine works through a number of different mechanisms," Hayes said. "It's been shown that it increases production of (the stress hormone) cortisol. It's been shown that it inhibits key enzymes in steroid hormone production while increasing others. It's been shown that it somehow prevents androgen from binding to its receptor."
The review also consolidates the evidence that atrazine undermines immune function in a variety of animals, in part by increasing cortisol.
"Cortisol is a nonspecific response to chronic stress," Beasley said. "But guess what? Wildlife in many of today's habitats are stressed a great deal of the time. They're stressed because they're crowded into little remnant habitats. They're stressed because there's not enough oxygen in the water because there are not enough plants in the water (another consequence of herbicide use). They're stressed because of other contaminants in the water. And the long-term release of cortisol causes them to be immuno-suppressed."
There also are studies that show no effects -- or different effects -- in animals exposed to atrazine, Beasley said. "But the studies are not all the same. There are different species, different times of exposure, different stages of development and different strains within a species." All in all, he said, the evidence that atrazine harms animals, particularly amphibians and other creatures that encounter it in the water, is compelling.
"I hope this will stimulate policymakers to look at the totality of the data and ask very broad questions," Hayes said. "Do we want this stuff in our environment? Do we want -- knowing what we know -- our children to drink this stuff? I would think the answer would be no."
ScienceDaily (Nov. 28, 2011) - An international team of researchers has reviewed the evidence linking exposure to atrazine -- an herbicide widely used in the U.S. and more than 60 other nations -- to reproductive problems in animals. The team found consistent patterns of reproductive dysfunction in amphibians, fish, reptiles and mammals exposed to the chemical.
Atrazine is the second-most widely used herbicide in the U.S. More than 75 million pounds of it are applied to corn and other crops, and it is the most commonly detected pesticide contaminant of groundwater, surface water and rain in the U.S.
The new review, compiled by 22 scientists studying atrazine in North and South America, Europe and Japan, appears in the Journal of Steroid Biochemistry and Molecular Biology.
The researchers looked at studies linking atrazine exposure to abnormal androgen (male hormone) levels in fish, amphibians, reptiles and mammals and studies that found a common association between exposure to the herbicide and the "feminization" of male gonads in many animals.
The most robust findings are in amphibians, said University of Illinois comparative biosciences professor Val Beasley, a co-author of the review. At least 10 studies found that exposure to atrazine feminizes male frogs, sometimes to the point of sex reversal, he said.
Beasley's lab was one of the first to find that male frogs exposed to atrazine in the wild were more likely to have both male and female gonadal tissue than frogs living in an atrazine-free environment. And in a 2010 study, Tyrone Hayes, a professor of integrative biology at the University of California at Berkeley and lead author of the review, reported in the Proceedings of the National Academy of Sciences that atrazine exposure in frogs was associated with "genetic males becoming females and functioning as females," Beasley said.
"And this is not at extremely high concentrations," he said. "These are at concentrations that are found in the environment."
The new review describes the disruptions of hormone function and sexual development reported in studies of mammals, frogs, fish, reptiles and human cells exposed to the herbicide. The studies found that atrazine exposure can change the expression of genes involved in hormone signaling, interfere with metamorphosis, inhibit key enzymes that control estrogen and androgen production, skew the sex ratio of wild and laboratory animals (toward female) and otherwise disrupt the normal reproductive development and functioning of males and females.
"One of the things that became clear in writing this paper is that atrazine works through a number of different mechanisms," Hayes said. "It's been shown that it increases production of (the stress hormone) cortisol. It's been shown that it inhibits key enzymes in steroid hormone production while increasing others. It's been shown that it somehow prevents androgen from binding to its receptor."
The review also consolidates the evidence that atrazine undermines immune function in a variety of animals, in part by increasing cortisol.
"Cortisol is a nonspecific response to chronic stress," Beasley said. "But guess what? Wildlife in many of today's habitats are stressed a great deal of the time. They're stressed because they're crowded into little remnant habitats. They're stressed because there's not enough oxygen in the water because there are not enough plants in the water (another consequence of herbicide use). They're stressed because of other contaminants in the water. And the long-term release of cortisol causes them to be immuno-suppressed."
There also are studies that show no effects -- or different effects -- in animals exposed to atrazine, Beasley said. "But the studies are not all the same. There are different species, different times of exposure, different stages of development and different strains within a species." All in all, he said, the evidence that atrazine harms animals, particularly amphibians and other creatures that encounter it in the water, is compelling.
"I hope this will stimulate policymakers to look at the totality of the data and ask very broad questions," Hayes said. "Do we want this stuff in our environment? Do we want -- knowing what we know -- our children to drink this stuff? I would think the answer would be no."
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