Great Lakes Eagles Struggle to Beat Pollution : Environment: Traces of banned toxins take their toll 20 years later on animals up and down the food chain.

More than two decades after the oily Cuyahoga River caught fire, after Lake Erie was declared dead and DDT was banned, eagles again soar above the Great Lakes.

They are not doing well.

Yearly, they return to try to colonize the contaminated shoreline. And yearly, scientist Bill Bowerman climbs to their nests to remove the unhatched eggs.

In the dead embryos and in the blood of surviving eaglets, the Michigan State University researcher sees high levels of the same poisons that wiped eagles out of the Great Lakes 20 years ago.

The birds are dying faster than they can reproduce, Bowerman says. For them and more than a dozen other animals that feed on Great Lakes fish, the shore is a zone of death and deformity.

It’s a red flag warning, Bowerman says, “a sign of what’s happening to everything in the food chain.”

The bald eagle is a perfect example, said Conservation Foundation researcher Dr. Theodore Colborn in Washington, D.C.

Up and down the inland sea, from cold, deep Lake Superior to the roiling St. Lawrence River, wildlife scientists tell of shore birds born with twisted beaks, clubfeet and stomachs outside their bodies. They tell of whales racked with cancers and diseases, of expanses of beach where mink have vanished, and of eagles that can barely reproduce.

In a report to the U.S.-Canadian International Joint Commission last year, Colborn listed 16 predator species whose shoreline populations have dropped in association with high toxin levels.

The killer is silent. Pesticides such as DDT, mirex and dieldrin and toxins such as PCBs and dioxin persist in the mucky lake sediments despite 20 years of cleanup efforts.

The toxins are picked up by worms and leeches and travel up the food chain, from smelt to trout to gulls to eagles. The concentrations of poisons increase 10 times at each level.

Contamination levels vary from lake to lake, but there are basin-wide warnings for humans to limit the sizes and kinds of Great Lakes fish they eat.

Fish contamination in some areas has dropped because of controls and bans on toxins pumped into the lakes by industry. Researchers say it will be a century or two before the vast lakes shed the poisons they have absorbed.

Meanwhile, the eagles try to return.

Bowerman’s research shows Michigan eagles on Lake Michigan and Lake Huron are reproducing at less than half the rate of those who nest inland.

A pair must raise one chick a year to keep the population stable. Lake Huron eagles have one chick for every three nests. After five years of eating Great Lakes fish--the time when inland birds reach their reproductive peak--shore bird reproduction in Michigan falls to one chick for every seven nests.

Wisconsin’s only Lake Michigan eagle nest, near Green Bay, has not produced a chick in four years. Another pair on the Straits of Mackinac near St. Ignace has not produced a chick in eight years.

In the Hiawatha National Forest in Michigan’s untamed Upper Peninsula, prime eagle territory, seven shoreline eagle pairs went three years before one of them produced a chick this year.

The eagle has made a remarkable comeback inland. Michigan, with 150 inland nesting pairs, has surpassed its federally set goal of 140 pairs. Minnesota reports 390 inland pairs and Wisconsin has 336, according to the U.S. Fish and Wildlife Service. In the three states, the eagle is classified as threatened, not endangered.

Bowerman believes that as those healthy eagles fly to the shore, their stunted efforts to reproduce are sapping the entire population.

There are no nests on Lake Ontario, the most contaminated of the Great Lakes. The Canadian side of Lake Huron is barren. Five of the eight U.S. Great Lakes states--Illinois, Indiana, Pennsylvania, New York and Minnesota--have no eagles on their shores.

“There’s some beautiful land there,” Bowerman said. “I don’t know why. I don’t know what the flow is from the pulp mills in Canada. I don’t know where it’s all coming from.”

He lost nine nests on Lake Superior this year. The parent birds have vanished.

Tim Kubiak of the Fish and Wildlife Service in Lansing said the eagles’ problems are a sign of the poor health of the entire Great Lakes basin, the world’s largest freshwater system.

“Growth problems, retardation, smaller head sizes, lower birth rates . . . we see it in mink, the birds,” Kubiak said. They are clues to the health of shore-dwelling humans.

The toxic problems show no signs of abating.

This spring, a research team found 22 deformities in cormorant chicks in Wisconsin’s Green Bay colony--a deformity rate of 1 in 72; 1 in 10,000 would be the norm.

Last year, Bowerman tested a Saginaw Bay eaglet with 2.25 parts per million of PCBs in its blood. The 5-week-old Lake Huron chick carried contamination 100 times higher than inland eaglets.

Like other Great Lakes researchers of terns and whales and mink, Bowerman is unable to say what the toxins actually do inside the bodies of their subjects.

“We’re seeing messages from the environment, indications that there are problems,” New York biologist Robert Foley said. His work shows elevated PCB concentrations in Lake Ontario mink--when he can find them. He thinks the toxins and the population problems are related, but he has yet to prove it.

Eight years of analyzing the blubber of dead beluga whales beached in the St. Lawrence River have given Canadian researcher Pierre Beland a chemical catalogue of the lakes.

The dead whales’ ailments run an odd list of cancers and diseases previously unseen in belugas.