Effects of biological behaviors of benthic bivalve (Corbicula japonica) on its passive transport

The bivalve Corbicula japonica is a popular food in Japan. The abundance of the clam in a lake changes over time. Clam transport is assumed to be passive even after the clam’s settlement. But it is not clear whether clams can be considered like sand particles, or whether biological features of the clams affect their movement. Features of clams that differ from sediment particles and may affect movement include secretion of mucous threads, use of the foot byssus, burrowing, as well as the clam’s shape. The aim of the work was to determine whether these biological features modified the interaction with the hydrodynamics which would affect the transport of juvenile and adult clams within a lake. We performed a series of laboratory experiments to measure the critical shear stresses of clams for transport. The mucous threads substantially decreased critical shear stress and in contrast, the byssus significantly increased critical shear stress. We then performed field measurements in Lake Shinji and evaluated the possibilities of clam transport depending on these biological behaviors. Thus, the evaluated shear stresses for clams will be applied into a clam dispersal and transport simulation model, which can be useful to understand the strategy of clams’ survivals.