|marine life off Palos Verdes|
Posted by on November 15, 2005 at 10:48:12:|
In Reply to: local fish with deformed reproductive organs posted by on November 14, 2005 at 16:19:12:
Some bottom-feeding fish found in waters around the Peninsula have male and female characteristics.
Scientists have discovered male fish living in Los Angeles and Orange County coastal waters that exhibit female characteristics, prompting further research into the effects of compounds in treated sewage wastewater on marine life.
Eleven of 64 bottom-dwelling fish captured in waters in and around the Palos Verdes Peninsula had ovary tissue in their testes, said Dave Montagne, a marine biologist with the Los Angeles County Sanitation Districts, one of several agencies participating in three studies being presented today at a conference in Baltimore.
Fish were collected from Point Conception to the U.S.-Mexico border in 2003, but only English sole and hornyhead turbot that feed on ocean sediments near sewage outfalls between Santa Monica and Huntington Beach exhibited the deformities, Montagne said.
That, coupled with experiments indicating sediments from Peninsula-area outfalls are more likely to produce deformities in healthy male fish, has left researchers with questions about the effects of leftover chemicals in treated wastewater -- like estrogens and estrogen mimics -- that sink to the ocean floor.
These chemicals have a history of creating animals showing characteristics of both sexes. An entire alligator population in a Florida lake became feminized after ingesting spilled pesticides, said Mark Gold, executive director of Heal the Bay. Male alligators were born with half-sized penises and female-level hormones.
But it could be years before scientists can pinpoint the exact cause of the fishes' deformities or fully grasp their long-term effects, said Daniel Schlenk, an aquatic ecotoxicologist at University of California, Riverside, who participated in the studies.
In Schlenk's study, fish exposed to sediment from the Peninsula grew five times more egg protein than those exposed to Huntington Beach sediment, and 10 times more than those exposed to a control sample.
"We measured the egg yolk protein," he said. "There were male gonads that eggs were found in. Obviously, eggs aren't supposed to be found in sperm-producing organs."
Schlenk was able to isolate the compounds in the sediment, but the most obvious -- a sunscreen agent -- was likely not the cause, he said.
"It's likely a lot of other compounds that we don't know the structure of," he said. "We found it was estrogenic, but at a concentration 100 times greater. It indicates that, yes, it's probably playing a role."
Schlenk suspects lingering compounds like the pesticide DDT, which has been banned for decades, and industrial PCBs and pharmaceuticals could be playing a role in the deformity -- an unsettling idea for environmentalists.
"The issues are the ocean's ecology," Gold said, "and the fact that we, as humans, are harming severely the ecology of our ocean. Are we repeating, 30, 40 years after the effects of DDT and PCBs, with a new suite of chemicals?"
Health officials have long recommended against eating certain fish caught locally because of DDT exposure. From the late 1940s to the early '70s, DDT -- mostly originating from the Montrose Chemical Co. plant formerly in Harbor Gateway -- was inadvertently flushed through the sewer system and deposited off of White Point. Even though DDT was banned in the United States in 1972, the factory continued to manufacture the pesticide -- widely used in the tropics to kill mosquitoes and stop the spread of malaria -- for export until 1983.
About 100 tons of DDT and 10 tons of PCBs still rest on the ocean floor off the Palos Verdes Peninsula. Every day, the Hyperion Treatment Plant near LAX and Carson's Joint Water Pollution Control Plant pump nearly 700 million gallons of treated wastewater several miles into the Pacific Ocean, far enough out to make human exposure relatively rare.
Montagne said the discovery does not pose a human health threat, but the effects on fish and other marine life remain unknown and a topic of future study.
"We're really just at the beginning," said Steve Weisberg, executive director of the Southern California Coastal Water Research Project, another participant in the study. "Preliminary observations lead us to believe this is clearly an area we need more work."
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