DDT AND OTHER CONTAMINANTS PERSIST IN PEREGRINES AND MARINE MAMMALS

FOR IMMEDIATE RELEASE

SANTA CRUZ, CA--Two decades after the U.S. government banned its use, the toxic pesticide DDT lingers tenaciously in the environment. It is borne on the wind, floats in the ocean, and concentrates in the tissues of predators from peregrine falcons to California sea lions.

Walter Jarman and his team of chemical detectives are hot on DDT's trail, tracing the poison from cities on the Atlantic seaboard to the supposedly pristine waters near the Aleutian Islands. Jarman, a postdoctoral researcher at the University of California, Santa Cruz, has studied the levels and effects of various contaminants in peregrines, sea lions, and a host of other animals for fifteen years. He focuses on DDT and other pesticides that act as nerve poisons; dioxins, dangerous chemicals produced by municipal incinerators; and PCBs, pollutants from the electrical industry.

In the last two years, Jarman and his colleagues have published eight scientific papers on contaminants in various animals. A new study on contaminants and weakened eggshells in peregrine falcons in the eastern U.S. is in press.

Jarman is well situated to make these contributions: He is affiliated with both the Santa Cruz Predatory Bird Research Group at UCSC, which restored California's population of peregrines, and the Institute of Marine Sciences, a major research unit at UCSC. His success also hinges on a worldwide web of scientists studying the effects of contaminants on living organisms. "That's the best part of being here­the network of biologists is phenomenal," Jarman says. "People are going all over the world doing basic physiology, so getting samples is easy. We're probably one of the only wet chemistry labs that has more samples than we know what to do with."

Peregrine falcons have given Jarman's group much of its work. Scientists first realized in the late 1960s that a metabolic product of DDT, called DDE, caused peregrine eggshells to become so thin that the mother bird crushed them or they dried out. In an effort to save peregrines from extinction in California, the Santa Cruz Predatory Bird Research Group began a captive breeding and release program in 1978. The program was remarkably successful: The number of known peregrine mating pairs in California rose from two in 1970 to more than 120 today. The group halted captive breeding last year and now concentrates on protecting and monitoring wild falcons.

Similar breeding programs, coupled with the banning of DDT in most industrialized countries in the 1970s, resulted in the recovery of peregrine populations in Europe and parts of North America. Nevertheless, peregrines in California still have fragile eggshells.

There are several reasons for the lingering problem, says Jarman. Residual levels of DDT in the state, while decreasing, are still high. Despite the ban, some legal pesticides still contain DDT. In addition, peregrines prey upon some migratory animals that may pick up the chemical in Central America, where DDT use continues.

Jarman is optimistic that DDT levels will decline. "I'm hoping we're on the cusp where levels will drop enough that the populations will become stable," he says. "Other populations, such as in Great Britain, are recovering and doing really well."

In contrast to the pesticide-plagued peregrines, California sea lions are a success story. "Pesticides have dropped dramatically and populations are increasing," Jarman says. In the 1960s and 1970s, sea lions carried a remarkable one pound of pesticide for every thousand pounds of fat. Today, the levels are down about a thousandfold to less than ten parts per million. Jarman expects that even these levels have some adverse effects, although scientists continue to debate hotly the nature of those effects. Speculations include weakened immune systems and premature births.

Jarman also studies healthy animal populations, including a school of bottle-nosed dolphins off Florida in the Gulf of Mexico. Randall Wells, assistant adjunct professor at UCSC's Institute of Marine Sciences, has kept detailed records of the behaviors and life cycles of dolphins near Sarasota, Florida, for twenty years. Although stranded dolphins from this population contain contaminants in their tissues, the rest of the animals have normal life spans, birth rates, and behavior patterns. Unless the stranded dolphins have particularly high levels of contaminants, which Jarman doubts, the contaminants do not appear to harm the animals. Therefore, Jarman plans to use contaminant levels in these dolphins as standards for a healthy, nonstressed population.

Jarman is launching a new study on Hawaiian owls, whose populations are plummeting due to a strange disease that may be linked to environmental contaminants. Together with Russell Flegal, professor of earth sciences at UCSC, and Jessica Bremer, an undergraduate student, Jarman will measure the levels of organic contaminants and heavy metals in the birds.

Jarman oversees numerous students and considers their contributions vital. "One thing I stress is that students go into the field to get samples," he says. "It makes them a hundred times more careful in the lab if they realize how difficult it was to get the samples." His students have flown to Alaska to collect otters, to Florida to bring back dolphin tissues, and to Hawaii to collect the diseased owls.

Editor's note: You may reach Jarman at (408) 459-3769 or wmjarma@ucsco.ucsc.edu. This press release was written by Alisa Zapp, a former intern in UCSC's Public Information Office.

This release is also available on UC Newswire, the University of California's electronic news service. To access by modem, dial (209) 244-6971.

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