Abstract:

Seagrass beds are one of the most productive ecosystems on Earth and an important source of ecosystem services. Accurate mapping of spatial patterns of seagrass species diversity are lacking at the national scale in China, while taxonomic information on Chinese seagrass species requires an urgent update. This lack of information hinders national conservation and restoration programs for seagrass biodiversity. In this article we review studies of diversity, distributions and degradation of seagrass in China. A total of 22 seagrass species distributed along China’s coastal regions belong to ten genera and four families, and account for about 30% of known seagrass species worldwide. A check of herbarium material stored in Sun Yat-sen University showed that the seagrass species previously identified as Posidonia australis in Hainan is in fact Enhalus acoroides. From our analyses, two Chinese seagrass biotas are proposed. These include the South China Sea Bioregion (SCSBR) and China’s Yellow Sea and Bohai Sea Bioregion (CYSBSBR). The SCSBR includes Hainan, Guangxi, Guangdong, Hongkong, Taiwan and Fujian provinces, and contains 15 seagrass species representing nine genera with Halophila ovalis being most widely distributed. The CYSBSBR includes Shandong, Hebei, Tianjin and Liaonin provinces and contains nine seagrass species belonging to three genera with Zostera marina being most widely distributed. The total distribution area for China’s seagrass meadows is estimated to be 8,765.1 ha, with Hainan, Guangdong and Guangxi provinces accounting for 64%, 11% and 10% of the area, respectively. Both the number and area of seagrass meadows are much higher in the SCSBR than in the CYSBSBR. In the SCSBR, seagrass meadows are mainly located in the eastern Hainan coast, Zhanjiang in Guangdong, Beihai in Guangxi and Dongsha Island in Taiwan, whereas in the CYSBSBR they predominate in Rongcheng in Shandong and Changhai in Liaoning. Halophila ovalis, Thalassia hemprichii and Z. marina are the dominated species in seagrass meadows in Guangdong and Guangxi, Hainan and Taiwan, Shandong and Liaoning respectively. Seagrass degradation in China is mainly attributed to human disturbances caused by fishing, aquaculture and sea reclamation. For conservation purposes we advise the following: (1) initiate an extensive national survey of spatial patterns of seagrass species diversity; (2) conduct long-term monitoring of typical seagrass meadows and establish a national seagrass monitoring network; (3) accelerate legislation for seagrass conservation and include some ecologically-significant seagrass meadows as reserves; (4) invest more finance in research on the restoration of seagrass beds and conservation of seagrass germplasm resources; (5) standardize the Chinese names of seagrassesin China.

Key words: seagrass meadow, seagrass species, Chinese seagrass biotas, degradation, human disturbances