Interactions between seagrass and its epiphytic algae:A review.

Seagrass bed is an important ecosystem in coastal wetland. The massive reproduction of epiphytic algae caused by eutrophication was supposed to be one of the main reasons inducing the worldwide large scale decline of seagrass beds in recent years. This paper reviewed the research advance in past two decades on the interactions between seagrass and its epiphytic algae, including the roles and functions of epiphytic algae in seagrass bed, the seagrass-epiphyte relationship in nutrient exchange, and the effects of over-densely covered epiphytes on seagrass leaves (mainly the decrease of light and nutrient availability). Some important aspects of further study on the seagrass-epiphyte relationship were suggested: 1) mechanisms in material exchange between seagrass and epiphytic algae, 2) competition in nutrient uptake between seagrass and epiphytic algae, 3) impact of epiphyte biomass on the decrease of light availability and photosynthesis capacity of seagrass, 4) contributions of seagrass and its epiphytic algae on the primary productivity of seagrass bed in relations to environmental factors, and 5) modeling of seagrass growth regulated by biological factors based on in-situ observation data.