Seagrass beds are important coastal ecosystems characterized by high biomass and primary production. The variation of seagrass primary production and biomass are determined by abiotic factors such as irradiance level, inorganic carbon supply, nutrient availability, water temperature, salinity, water velocity, iron deficiency and pollutants. Herbivory and the interaction with epiphytes are the most important biotic factors affecting the biomass and production of seagrasses. In general, the abiotic factors display optimal ranges for seagrass growth while the biotic factors exist double faced effects on it. Further research will be focused on development of research methods and comparative analysis based on larger spatial and temporal scales.