Chemical may be harming sturgeon

A widely used paint chemical known as TPT is leaking into the Yangtze River and may be responsible for deformities and decreasing numbers of rare wild Chinese sturgeon, Reuters reported, citing a study published in the Proceedings of the National Academy of Sciences. Chinese sturgeon are among the first class of protected animals in China.

Writing in the American journal, researchers said a significant proportion of juvenile sturgeon caught at the Yangtze had either one or no eyes, or had misshapen skeletons. “Maternal transfer of TPT … in eggs of wild Chinese sturgeon poses a significant risk to the larvae naturally fertilized or hatched in the Yangtze River,” wrote the researchers, led by Hu Jiangying of Beijing University’s College of Urban and Environmental Sciences.

Chinese sturgeon, which are slow-growing, have existed for 140 million years. The fish has an increased capacity to accumulate TPT (or triphenyltin), a tin-containing chemical used in paints to prevent the fouling of ship hulls and fishing nets. In China, it also is used in fungicide to treat crops; a derivative is used to eliminate snails in paddy fields.

The experts collected two- and three-day-old Chinese sturgeon larvae from a spawning area below the Gezhouba Dam, 38 kilometres downstream from the Three Gorges Dam on the Yangtze River. After hatching in a laboratory in Jingzhou city in central Hubei Province, 6.3% were found with skeletal deformities and 1.2% were missing at least one eye.

Two adult males and two adult females of the Chinese sturgeon also were taken from the Yangtze for artificial propagation. Of the juveniles born later, 3.9% were observed to have malformed skeletons, while 1.7% had one or no eyes. In further testing, in which the researchers injected TPT into batches of Chinese and Siberian sturgeon eggs, an increase in the occurrence of deformities was found. The rate of increase, say the researchers, was consistent with wild sturgeon exposed to similar concentrations of TPT.

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