UC Davis researcher finds contamination in bass
Chris Bowman
The Sacramento Bee
12/09/2008
Striped bass in the San Francisco Estuary are producing deformed offspring as a result of contamination from a mix of pesticides, industrial chemicals and flame retardants, scientists have found.
A team of University of California, Davis, researchers reported "a conclusive line of evidence" that bass are accumulating these persistent chemicals and passing them to their young.
The recently published findings add to a growing body of evidence that pollution in the estuary is contributing to the collapse of fish populations, along with introduced clams, wastewater from sewage treatment plants and massive water exports to Southern California.
The findings have implications for people because the estuary is a source of drinking water for 25 million Californians and most farms in the state, said David Ostrach, a research scientist at the UC Davis Center for Watershed Sciences.
"If the fish living in this water are not healthy and are passing contaminants to their young, what is happening to the people who use the water, are exposed to the same chemicals or eat the fish," Ostrach said in a news release Monday.
Using new analytical methods, the researchers found that the days-old offspring of estuary bass had significantly smaller brains and livers, curved spines and far less protein-rich yolk in their sacs to survive, compared with larvae from hatchery bass raised in clean water.
"Just before first feeding these larvae had virtually no source of energy available to search for food or avoid predators," Ostrach said.
The findings, published online Nov. 24 in the Proceedings of the National Academy of Sciences, add to evidence that highly toxic pesticides abandoned years ago are still working their way up aquatic food chains and causing damage.
Though the pesticide DDT and industrial coolants called polychlorinated biphenyls or PCBs were banned more than 30 years ago, these chemicals were found at significant levels in the eggs from the estuary fish, the study said.
Eggs from the control group of hatchery-reared female bass had only comparatively minuscule levels of contaminants that researchers attributed to the hatchery food that contained ground fish.
The bass research is part of an ongoing series of studies by a large team of university and government scientists to determine the role contaminants play in the ecological collapse of the estuary. Striped bass, once part of a thriving commercial and sport fishery, have steadily declined in the past 30 years along with the Delta smelt, the longfin smelt and the threadfin, said Ostrach, who has studied the declines since 1988.
The flame retardants, called PBDEs or polybrominated diphenyl ethers, are long-lived and are accumulating in humans. Recent studies have shown that Californians have double the amount of these retardants in their blood as the national average and hundreds of times greater in the breast milk of Bay Area mothers than those elsewhere in the world...
