China is a cultural region and ancient civilization in East Asia. China refers to one of the world's oldest civilization comprising successive states and cultures dating back more than 6,000 years.

China has one of the world's longest periods of mostly uninterrupted civilization and one of the world's longest continuously used written language systems. The successive states and cultures of China date back more than six millennia. For centuries, China was the world's most advanced civilization, and the cultural center of East Asia, with an impact lasting to the present day. China is also the source of many great technical inventions developed throughout world history, including the four great inventions of ancient China: Paper, the compass, gunpowder, and printing.

China's overall population exceeds 1.3 billion, about one-fifth of the world's population

Distribution of Seagrass in South China

Seagrass meadows in China's waters of the South China Sea are mainly distributed in Guangdong Province, Guangxi Province, Hainan Province and Hong Kong.

In Guangdong Province, seagrasses are located at Liusha Bay of Leizhou Peninsula, Donghai Island of Zhanjiang and Hailing Island of Yangjiang. The seagrass meadows of Liusha Bay distribute along the coast. The dominant species Halophila ovalis covers more than 98% of the seagrass area.

In Guangxi, 540ha of seagrass are mainly located at Hepu and Pearl Bay in eight locations, namely Dianzhousha, Xialongwei, Beimu Salt-Field, Yingluo Bay, Danshuikou at Shatian, Shanliaojiuhejingdi, Gaoshatou and the foot of Ronggen Hill. The area of each seagrass meadow ranges from 20ha to 250ha. The dominant species in the Hepu seagrass meadow is Halophila ovalis.

In Hainan Province, seagrasses are mainly located at Li'an Bay, Xincun Bay, Long Bay and Sanya Bay. Seagrasses in Li'an Bay are distributed around the lagoon, Enhalus acoroides is the dominant species, whilst the total area of Halophila ovalis and Halodule uninervis is less than 10%.

In Xincun Bay, 200ha of seagrasses distribute at the south of the lagoon, the dominant species is Enhalus acoroides, and the total area of Halodule uninervis is less than 8%. In Long Bay, seagrasses are located at the inner side of the coral reef in belt pattern. The area of seagrass at Shanya Bay is less than 1ha, Thalassia hemprichii is its dominant species. In Hong Kong, a small area of seagrass occurs at Shenzhen Bay and Dapeng Bay.

Threats to Seagrass in South China

According to results of a series of field surveys, seagrass meadows in South China Sea are facing serious threats, a consequence of poor public awareness of the importance of seagrasses. Threat include:

Construction of shrimp ponds
In recent few years, shrimps culture has been blooming in the coastal area of South China Sea, and sea reclamation for shrimp culture is the main form. Large area of intertidal seagrasses have been replaced with shrimp ponds. This is prevalent at Liusha Bay and Hailing Island in Guangdong Province, Pearl Bay in Guangxi and Li'an Bay in Hainan Province.

Aquaculture
Seagrass habitats are being replaced with seashell (eg oysters, pearl, etc.) and algal culture farms. About 100ha of seagrass was destroyed at Dianzhou in Hepu (Guangxi) to make way for seashell culture, with broken pegs and waste seashells found throughout the area. Also large areas of the Liusha Bay seagrass meadow are used to cultivated shellfish. Similarly, large areas of seagrss in Li’an and Xincun Bays (Hainan Province) are used for algal culture.

Net fishing
As seagrasses support abundant fishery resources, local people set fishing nets on the meadows. Activities, such as piling and trampling on seagrasses during fishing, can damage the seagrasses. Also, the large and long nets accidentally trap dugongs feeding on the seagrass. For example, a dugong was caught when feeding on the Hepu seagrass meadow in Guangxi, and was safely released back to sea by the fishermen.

Poisoning and blasting and electron capturing prawns and fishes
Prawns are the main fishery resource of seagrass meadows. After ebb tide, numbers of fishermen catch fish by poisoning, blasting or electro fishing. These activities are universal on seagrass meadows along the coastal area of South China, especially at Liu'sha Bay in Guangdong province. Blast fishing is quite prominent, and can be very damaging to seagrass.

Shellfish digging
Digging Sipunculus nudus, Linnaeuses, Phascolosoma esculentaes and shellfish are universal on the most of the seagrass meadows along the coastal area of South China. Hundreds of people, including children, dig for shellfish in the seagrass meadows of Hepu (Guangxi) and Liusha (Guangdong). Shellfish are an important source of food and income for the local people. Shellfish digging is very destructive, exposing rhizomes and loosening mud to flow and thus cover the seagrasses.

Trawling
There are more than 400 trawlers working in the shallow (<10m) sea areas of Hepu. Intensive bottom trawling can be physically destructive by uprooting plants and disturbing the sediment.

Pollution
Pollutants discharged from both land and sea increases the concentrations of non-biodegradable organic matter, nutrients and suspended substances. For example, wastes from restaurants and visitors are discharged into the sea near the seagrass meadow of Xincun Bay, reducing water quality and the condition of the seagrasses.

Port and shipping channel dredging
Maintenance dredging of ports and access channels is having direct and indirect impacts on seagrass. Direct impacts include physically removing plants in the construction areas and burial in the dumping grounds. At the same time, indirect impacts on seagrasses at the non-construction areas from reduced light availability resulting from elevated suspended sediments. The occurs quite universally at Hepu seagrass meadow in Guangxi.

Natural impacts, including Typhoons
The storm tides and storm waves caused by typhoons uproot plants or mobilise sands to cover seagrasses. For example, a typhoon in Sep.2002 destroyed the seagrass meadows at Hepu of Guangxi, and recovery took many months.