Abstract: Silver carp stocking can supress the growth of zooplankton and net-phytoplankton,therefore is favorable to the growth of nano-phytoplankton. Fish activities may disturb the vertical distribution of nutrients in shallow waters. Fishing reduces the overall nutrient content in water ,however,stocking of the fish may accelerate nutrient cyclings by increasing the amount of nutrients that go into higher trophic levels,and therefore can more effectively reduce nuttient content and improve water quality. These functions are affected by water depth,trophic status istructure of plankton community,stocking density iseasons etc.

Key words: Gaoqiao, mangrove, sediment, grain size, organic matter, spatial interpolation.