A compilation of data on biomass and growth allowed an examination of the intraspecific plasticity in Tha/assia hemprichii which played key roles to develop site-specific growth strategies for this species in Xincun Bay. The results showed the difference in rhizome elongation rates which explained most of the variation of biomass and growth within species. The seagrass T. hempdchii in Xincun Bay adjusted its vertical and horizontal rhizome elongation rates alternatively in response to light level and temperature changes, resulting in the variation of shoot densities and above biomass in return. The vertical and horizontal rhizomes elongated at rates of 2.38 and 24.4 cm yr1 in summer while 1.87 and 29.2 cm yr^-1 in winter respectively. The shoot density ranged from 822 to 941 shoots m^2 with a peak in summer and a trough in winter which was similar to that of biomass. The growth strategy enabled T. hempdchii to minimize the negative effects of desiccation in summer as well as light reduction in winter.
