SEA GRANT TIP SHEET FOR APRIL 21, 1999
FISH DEFORMITIES MAY BE LINKED TO CHEMICAL INHIBITORS
South Carolina Sea Grant-funded research points to environmental chemicals that mimic retinoids as a possible source for increasing numbers of deformed aquatic life such as frogs and fish. South Carolina Sea Grant researchers Denice Smith and Robert McCarthy and graduate student Mark Vandersea have linked a series of deformities seen in the environment, including multiple limbs, to disruptions in embryonic retinoid levels.
Retinoids, such as retinoic acid, are important in regulating the early development of all vertebrate embryos, including humans. Research results suggest that chemicals in the environment may mimic retinoids, much like the more publicized "endocrine disruptors" may mimic estrogen and testosterone hormones. When this occurs, a chemical that can cause embryonic deformities replaces the normal retinoid. Methoprene, a mosquito and flea pesticide, is one chemical that has been suggested as mimicking natural retinoid regulators. "Since retinoic acid acts on cells very early in development, it influences the patterning of the brain, heart, appendages, and other organs. To develop normally, embryos need to make retinoic acid themselves, in just the right amounts," said McCarthy. "If fish embryos are exposed to additional or limiting retinoic acid, the balance is disrupted and they develop abnormally, resulting in the duplication or deletion of the fins, similar to the frog limb deformities which have been described," said Smith.
The researchers are now developing sensitive tools to detect the presence of retinoic acid-like compounds in inland and coastal waters. These tools could provide natural resource managers with early warnings of the presence of retinoid-like molecules in aquatic environments.
CONTACT: Denice Smith, Sea Grant Researcher, (O) (843) 406-4018; [email protected];
Robert McCarthy, Sea Grant Researcher, (O) (843) 406-4018; [email protected], (Charleston, SC).
OFFSHORE PALOS VERDES DDT MAY HAVE SPREAD, NOT DISINTEGRATED
A study conducted by Eddy Zeng, a University of Southern California Sea Grant researcher, suggests that the huge volume of DDT left in the offshore sediments of the Palos Verdes Shelf (PVS) may be spreading to other areas.
The level of DDT detectable in the PVS sediments has declined steadily since production of the insecticide was banned in 1970. It was believed that the decline was due largely to chemical decay of the substance over time. Zeng's study, however, indicates that the decline may also be due to processes which continue to pull the substance out of contaminated sediments and distribute it in water currents to areas outside the zone where it was originally deposited by sewage outflow between 1950 and 1970.
Zeng's research shows that DDT is widely distributed in the PVS water column and appears to be leaching from the sediments. This research also suggests that DDT in PVS could be moving to other areas through the movement of ocean currents. The widespread dispersal of DDT in sediments of the Santa Monica and San Pedro basins supports this theory.
Zeng, along with USC professor Richard Teh-Lung Ku, is now looking into the chemical fates of DDT in these contaminated sediments and surrounding seawater.
CONTACT: Phyllis Grifman, Sea Grant Communicator, (Los Angeles, CA), (O) (213) 740-1963; [email protected]
MINNESOTANS OPTIMISTIC ABOUT LAKE QUALITY
Close-to-home location, scenery and fishing are the top three reasons Minnesotans place a high value on their lake resources according to a survey of 2,000 residents by Minnesota Sea Grant and the Minnesota Department of Natural Resources.
Over 90 percent agreed that lakes are important because of their beauty and for their fish and wildlife. They are also valued for both recreational (80%) and economic (70%) reasons. Minnesotans are optimistic about the future of their lakes with 76 percent believing water quality will either remain the same or improve.
Northeast region residents are more optimistic than residents in other regions are, and this may be due to lakes in the region having less development than elsewhere. This difference may have implications for the state's resort industry and on future management efforts.
Most respondents favored voluntary and educational approaches to regulatory solution to lake issues.
CONTACT: Keith Anderson, Minnesota Sea Grant Water Resource Educator, (Duluth, MN), (O) (218) 726-7524; [email protected]
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