China’s recent economic boom has come at the cost of polluted landscapes and newly endangered species, and now a new study explains how another species has been left teetering on the brink of extinction. The endangered Chinese sturgeon live in the East China and Yellow seas and return to China’s Yangtze River to spawn. Construction of dams on the river is thought to have contributed to a decline in the species, and an artificial propagation effort has not resulted in recovery of the fish [AP]. But the new study shows that a chemical called triphenyltin (TPT), which is commonly used in paint, may be the true culprit behind the sturgeon’s decline.
The tin-containing organic compound TPT is extensively used in paints to prevent the fouling of ship hulls and fishing nets. It is also used in fungicide to treat crops in China. A derivative of TPT is also used to eliminate snails in paddy fields [Reuters]. In the study, published in the Proceedings of the National Academy of Sciences, researchers found that river water polluted with the chemical is producing sturgeon with misshapen skeletons and deformed eyes.
The experts collected two- and three-day old Chinese sturgeon larvae from a spawning area below the Gezhouba Dam, which is 38 km (24 miles) downstream from the Three Gorges Dam on the Yangtze River. They later hatched in a laboratory in Jingzhou city in central Hubei province where 6.3 percent were found with skeletal deformities and 1.2 percent had either no eyes or just one eye [Reuters]. Researchers tested the fish, and found high concentrations of TPT in their bodies. The research group also injected TPT into Chinese sturgeon eggs in the lab, and found that the fish that hatched had similar deformities.
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Image: National Academy of Sciences, PNAS