Guangzhou is Etoposide the largest city of southern China and the third largest Chinese city. As of 2010, the city’s administrative area had a population of 12.8 million, making Guangzhou the most populous southern city. Not established until 1979, when it was no more than a market town situated on the border with the then British colony of Hong Kong, Shenzhen has become one of the largest cities in the Pearl River delta as well

as the largest manufacturing base in the world. Today, this Special Economic Zone (SEZ) is the 10th most populous city in China with some 10.4 million residents. Some estimates place the population surrounding the Pearl River Delta Economic Zone, which can today be referred to as a Mega City – the world’s first megalopolis – at 40 million including Shenzhen (>10 million), Dongguan (>8 million), Foshan (>7 million), Jiangmen (>4 million) and Zhongshan (>3 million). In 2008, Guangzhou alone was identified as a Beta World City by the Globalization and World Cities Research Network. If, therefore, Guangzhou itself, sitting at the head of the Pearl’s estuary, is included we can estimate a delta-wide urban population of some 150 million people. This

does not, however, include either the gambling city of Macau, until 1999 a former Portuguese colony, with a resident population of ∼0.5 million (but a much greater transient one) nor, until 1997, the former British Cetuximab research buy colony of Hong Kong, which with a population of >7.2 million people (and a transient one of >126 million), is classified as an Alpha + City. With a land area of only 1104 km2, the Special Administrative Region of Hong Kong’s lack of space has created the world’s most vertical city. Kowloon, with a population density of ∼44,000 km2 ranks as one of, if not the, most dense human conurbations ever known. The Pearl River’s delta almost today, therefore,

is probably home to, conservatively, over 160 million people but growth has not yet ended. Regional goals for 2020 include the development of two or three new cities, the expansion of road, rail, seaport and airport infrastructures and the construction of the 50 km long Hong Kong–Zhuhai–Macau Bridge – across the Pearl currently traversed by thousands of ferries each day. Since the end of the last ice age, sea levels have risen in southern China by over 10 m (but were even higher in the Early Holocene) so that the Pearl River’s delta contains hundreds of little islands (former mountain tops), there being some 235 within Hong Kong’s 1650 km2 territorial waters alone. And, because of the vast amounts of silt deposited by the river, estimated at ∼86 million tonnes each year, the estuary’s flanks are bordered (or used to be) everywhere by mangrove stands – these lie close to the northern limits of the component species’ ranges.