Seagrass beds are highly productive coastal ecosystems and provide habitat for a diverse and abundant range of associated flora and fauna. In this paper the spatial distribution of seagrasses throughout the world has been described and the effects of various environmental factors on seagrass health have been reviewed. The ecosystem services provided by seagrasses include nutrient cycling, provision of fish habitats, protection from coastal erosion and buffering of the impacts of poor water quality. Major environmental factors influencing seagrass distribution and abundance include temperature, salinity, nutrients, light intensity, grazing and climate change. Further research is required on Chinese seagrasses to examine the ecology, ecosystem functioning and, the environmental factors influencing distribution and abundance. In addition, at some locations, the possibility of restoring degraded seagrass beds could be investigated.