Pollution of China's waterways has led to the destruction of huge swathes of ecologically valuable wetlands and a marked increase in algae blooms which choke marine life, says a new study recently published in the science journal Nature
The findings, part of an eight-year long survey carried out by 30,000 experts from the Chinese State Oceanic Administration, show that roughly 90% of coastal cities endure periodic water shortages. China's mangrove swamps have decreased in area by 73% and its coral reefs by 80% since the 1950s. Its coastal wetlands have also shrunk by 57%, a third of which is due to land reclamation.
The survey also revealed that over the past decade there has been a steady rise in pollutants discharged into estuaries. And around 50 estuaries are said to have been contaminated with heavy metals, the insecticide dichlorodiphenyltrichloroethane (DDT), and petroleum hydrocarbons.
Such pollutants are a direct cause of the red, green, and brown tides which over the past 20 years have become increasingly common in China's seas. Such vast nutrient-rich algae blooms quickly decay, absorbing oxygen and releasing nitrogen, creating hypoxic conditions for marine life. Speaking to the news site Xinhua, Professor Zhou Mingjiang of the Institute of Oceanology believes that such coloured tides could bring the destruction of fisheries in east China.
According to the science website Wired
, although experts such Gao Kunshan of Xiamen University have called the project "the most comprehensive marine survey so far", others believe that a lot more needs to be done to assess coastal ecosystems.
Sun Song, director of the Chinese Academy of Sciences' Institute of Oceanology in Qingdao, believes that the survey doesn't give a clear picture of how ecosystems are changing. For example, preliminary research conducted near Xiamen suggests that the coastal waters there are becoming more acidic, which has knock-on effects for the ecosystem of the area.
At the moment, however, it is unclear how serious or extensive the problem is, because studies so far are piecemeal. In short, the survey does not go far enough into the effects of the decline to offer any real solutions or long-term ramifications. Without real investigation, directing policy will be difficult, said Sun.
William Lawrenson is intern in chinadialogue's Beijing office