Effects of the stocking density and body size of the mitten crab (Eriocheir sinensis) on aquatic plant biomass

Experiments in tanks and cages were conducted to examine the effects of sto cking density and body size of the Mitten crab (Eriocheir sinensis) on tran splanted submersed macrophyte biomass. The early juvenile crab with 7.0 +/- 0.6 mm. carapace width (CW) had little effect on plant biomass, regardless of the stocking densities. However, larger crabs (CW: 18.0 +/-2.2,35.0 +/-3 .6, and 60.0 +/-5.7 mm) significantly influenced plant biomass, especially at large stocking densities. Predictive models, using crab body size and st ocking density, were generated to demonstrate effect of the mitten crab on the changes Of plant biomass. The results indicate that dense mitten crab p opulations may adversely affect aquatic plant communities, particularly whe n its animal food resources are scarce.