A U.S. Navy study has found elevated levels of toxic chemicals in the carcasses and food of endangered birds at the Anaheim Bay National Wildlife Refuge.
"It's less than the level that would kill them," said Joe Davidson, a spokesman for the Seal Beach Naval Weapons Station which includes the 911-acre refuge. But, he said, "it's a cause for concern."
According to the study, the elevated levels of cadmium, chromium, copper, lead, nickel and zinc, all poisonous heavy metals, were found in dead California least terns and light-footed clapper rails, both rare birds included on the federal and state endangered species list. The birds apparently had died of natural causes, Davidson said.
The potentially toxic substances also were found in smaller animals normally eaten by the birds, including horned snails, salt marsh snails and deep body anchovies.
In addition to the potentially toxic metals, Davidson said, the study found small amounts of chemical PCBs and traces of DDT, a dangerous pesticide.
The ongoing study was begun in 1991 by the Navy with the help of the U.S. Fish and Wildlife Service to assess the impacts of naval base operations on the two endangered birds, especially in ponds on the refuge fed by Anaheim Bay.
While the study does not speculate on sources of the contamination, it does note that construction of the ponds by the Port of Long Beach has significantly increased the volume and velocity of bay water flowing into the refuge.
The potential effects of the toxic materials on the birds include altered growth patterns, reduced survival of the young, loss of appetite, lethargy, weakness and difficulty in reproducing. At high levels, the toxic metals and chemicals could kill some birds.
While noting that the situation does "not warrant a concern for immediate remediation," the study recommends that food-chain organisms and sediment in the refuge be monitored annually for evidence of further contamination. Davidson said the Navy will do that and will "take other necessary actions to be determined at a later date."