Shanghai’s breakneck growth has brought with it huge environmental problems, water pollution chief among them. Falling levels of fish, particularly protected species such as the Chinese sturgeon, are a concern. Suzhou Creek, once home to many fish species, became so polluted by the 1970s that nothing could survive in it. Clean-up work in the creek has begun and, together with improvements to the sewage pumping stations discharging into it, should be finished by the end of 2010. Freshwater Chinese suckers, a native fish, are being reintroduced to test the environment. Shanghai’s most important ecosystem is the Chongming Dongtan Nature Reserve on the eastern end of Chongming Island. With its extensive fresh and saltwater marshes, reedbeds, tidal creeks and mudflats, the island provides refuge for millions of birds and rich, offshore marine life.­­­­