Using new analytical techniques, the researchers found that offspring of estuary fish had underdeveloped brains, inadequate energy supplies and dysfunctional livers. They grew slower and were smaller than offspring of hatchery fish raised in clean water.
"This is one of the first studies examining the effects of real-world contaminant mixtures on growth and development in wildlife," said study lead author David Ostrach, a research scientist at the UC Davis Center for Watershed Sciences. He said the findings have implications far beyond fish, because the estuary is the water source for two-thirds of the people and most of the farms in California.
"If the fish living in this water are not healthy and are passing on 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.
"We should be asking hard questions about the nature and source of these contaminants, as well as acting to stop the ongoing pollution and mitigate these current problems."
The new study, published online Nov. 24 by the journal Proceedings of the National Academy of Sciences, is one of a series of reports by Ostrach and UC Davis colleagues on investigations they began in 1988. Their goal is to better understand the reasons for plummeting fish populations in the estuary, an enormous California region that includes the Sacramento-San Joaquin River Delta and San Francisco Bay.
The estuary is one of the world's most important water supplies for urban use and agriculture, and is also one of the most contaminated aquatic ecosystems.
The ominous decline in estuary populations of striped bass, delta smelt, longfin smelt and threadfin shad, named the "pelagic organism decline," or POD, by the region's environmental scientists, was first reported at the turn of the century and has continued to worsen through 2007.
Ostrach's lab at UC Davis is part of the multi-agency POD research team and charged with understanding contaminant effects and other environmental stressors on the entire life cycle of striped bass.
Studies of striped bass are useful because, first, they are a key indicator of San Francisco Estuary ecosystem health and, second, because contaminant levels and effects in the fish could predict the same in people. For example, one of the contaminants found in the fish in this study, PDBEs, have been found in Bay Area women's breast milk at levels 100 times those measured in women elsewhere in the world.
The new study details how Ostrach and his team caught gravid female striped bass in the Upper Sacramento River, then compared the river fishes' eggs and hatchlings (larvae) to offspring of identical but uncontaminated fish raised in a hatchery.
In the river-caught fishes' offspring, the UC Davis researchers found harmful amounts of PBDEs, PCBs and 16 pesticides.
PBDEs (polybrominated diphenyl ethers) are widely used flame retardants; PCBs (polychlorinated biphenyls) are chemicals once used in making a range of products, from paper goods to electric transformers; and the pesticides detected include some currently widely used in agriculture, such as chlorpyrifos and dieldren, and others banned decades ago, such as DDT.
These compounds are known to cause myriad problems in both young and adult organisms, including skeletal and organ deformities and dysfunction; changes in hormone function (endocrine disruption); and changes in behavior. Some of the effects are permanent. Furthermore, Ostrach said, when the compounds are combined, the effects can be increased by several orders of magnitude.
Ostrach's co-authors Janine Low-Marchelli and Shaleah Whiteman are former UC Davis undergraduate students. Co-author Kai Eder was Ostrach's postdoctoral scholar in Joseph Zinkl's laboratory in the UC Davis School of Veterinary Medicine.
Since 1988, the Ostrach laboratory has received more than $1.5 million in funding from agencies working on Bay-Delta ecosystem problems and expects to conduct an additional $1.5 million worth of studies in the next few years. Key funders include the UC Davis School of Veterinary Medicine, California's Department of Water Resources, State Water Resources Control Board and Department of Fish and Game, San Francisco Estuary Institute and the U.S. Fish and Wildlife Service.About UC Davis
Davis Ostrach | EurekAlert!
Preservation of floodplains is flood protection
27.09.2017 | Technische Universität München
Conservationists are sounding the alarm: parrots much more threatened than assumed
15.09.2017 | Justus-Liebig-Universität Gießen
University of Maryland researchers contribute to historic detection of gravitational waves and light created by event
On August 17, 2017, at 12:41:04 UTC, scientists made the first direct observation of a merger between two neutron stars--the dense, collapsed cores that remain...
Seven new papers describe the first-ever detection of light from a gravitational wave source. The event, caused by two neutron stars colliding and merging together, was dubbed GW170817 because it sent ripples through space-time that reached Earth on 2017 August 17. Around the world, hundreds of excited astronomers mobilized quickly and were able to observe the event using numerous telescopes, providing a wealth of new data.
Previous detections of gravitational waves have all involved the merger of two black holes, a feat that won the 2017 Nobel Prize in Physics earlier this month....
Material defects in end products can quickly result in failures in many areas of industry, and have a massive impact on the safe use of their products. This is why, in the field of quality assurance, intelligent, nondestructive sensor systems play a key role. They allow testing components and parts in a rapid and cost-efficient manner without destroying the actual product or changing its surface. Experts from the Fraunhofer IZFP in Saarbrücken will be presenting two exhibits at the Blechexpo in Stuttgart from 7–10 November 2017 that allow fast, reliable, and automated characterization of materials and detection of defects (Hall 5, Booth 5306).
When quality testing uses time-consuming destructive test methods, it can result in enormous costs due to damaging or destroying the products. And given that...
Using a new cooling technique MPQ scientists succeed at observing collisions in a dense beam of cold and slow dipolar molecules.
How do chemical reactions proceed at extremely low temperatures? The answer requires the investigation of molecular samples that are cold, dense, and slow at...
Scientists from the Max Planck Institute of Quantum Optics, using high precision laser spectroscopy of atomic hydrogen, confirm the surprisingly small value of the proton radius determined from muonic hydrogen.
It was one of the breakthroughs of the year 2010: Laser spectroscopy of muonic hydrogen resulted in a value for the proton charge radius that was significantly...
17.10.2017 | Event News
10.10.2017 | Event News
10.10.2017 | Event News
20.10.2017 | Information Technology
20.10.2017 | Materials Sciences
20.10.2017 | Interdisciplinary Research