Deep-water marine fish living on the continental slopes at depths from 2000 feet to one mile have liver pathologies, tumors and other health problems that may be linked to human-caused pollution, one of the first studies of its type has found, according to Phys.org.
The research, conducted in the Bay of Biscay west of France, also discovered the first case of a deep water fish species with an "intersex" condition, a blend of male and female sex organs. The sampling was done in an area with no apparent point-source pollution, and appears to reflect general ocean conditions.
The research is of particular interest, OSU researchers said, when contrasted to other studies done several years ago in national parks of the American West, which also found significant pollution and fish health impacts, including male fish that had been "feminized" and developed eggs.
"In areas ranging from pristine, high mountain lakes of the United States to ocean waters off the coasts of France and Spain, we've now found evidence of possible human-caused pollution that's bad enough to have pathological impacts on fish," said Michael Kent, a professor of microbiology in the OSU College of Science, co-author on both these research projects and an international expert on fish disease.
"Deep in the ocean one might have thought that the level of contamination and its biological impact would be less," Kent said. "That may not be the case. The pathological changes we're seeing are clearly the type associated with exposure to toxins and carcinogens." However, linking these changes in the deep water fish to pollution is preliminary at this time, the researchers said, because these same changes may also be caused by naturally-occurring compounds. Follow up chemical analyses would provide more conclusive links with the pathological changes and man's activity, they said.
Few, if any health surveys of this type have been done on the fish living on the continental slopes, the researchers said. Most past studies have looked only at their parasite fauna, not more internal biological problems such as liver damage. The issues are important, however, since there's growing interest in these areas as a fisheries resource, as other fisheries on the shallower continental shelf become depleted.
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