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Podcast Transcript: You’ve probably heard about mercury contamination in fish. But a new study says the toxin has climbed out of the water. Researchers from the College of William and Mary say landlubbing insects near the Shenandoah River have elevated levels of mercury in their blood—and so do the birds that eat them. The report appears in the April 18th issue of the journal Science.
The scientists tested mercury in 13 insect-eating bird species and found that twelve had dangerously high levels. They then examined the birds' food supply, literally snatching spiders, moths and grasshoppers out of the mouths of babies in their nests. These tasty morsels all contained mercury. And spiders, which sit higher up the food chain, had even more mercury than fish collected from the river.
The news is alarming, since mercury can cause reproductive failure and even death at low concentrations. The researchers now want to know how a problem thought to be confined to a single ecosystem is spreading. They speculate that contaminated aquatic insects, or maybe polluted floodwaters, are helping mercury creep out of the river and take to the wing.