REQUIREMENT FOR AND DAMAGE TO VALLISNERIA SPIRALIS BY ERIOCHEIR SINENSIS

Submerged macrophytes play an important role both in producing cash aquatic animals and keeping good quality of lake water.By transplanting Vallisneria spiralis in 8 concrete tanks to form artificial habitats for yearling Eriocheir sinensis to live in and grow up for 4 months, the mutual effects of these two species were examined.This crustacean, particularly the male crab, did damage to this submerged plant, while the plant provides defiladed habitats rather than food for the animal.A liner relationship between the damage rate (VD, g/m2/ind/d) and the crab stocking density (SF, female; SM, male, ind/m2) was found to be as VD = 2.08 + 0.11SF + 5.83 SM.The carrying capacity of this plant for cultur-ing crab was determined to be 1.08 ind/100g/m2 .A model of the crab growth (SGR, %/d) with the biomass of V.spiralis (VP, g/m2) was established as SGR = 0.464 + 0.003VP.The carb would grow to their marketable size in condition that the initial standing biomass of V.spiralis exceeded 124g/m2.The above results could be used as a guide for rearing crab and keeping renewable resources of submerged aquatic weed in macrophytic lakes.