Preliminary study of management of red tide water by the filter feeder Mytilus edulis galloprovincialis

Abstract

An examination was made to determine whether red tide water masses could be controlled by the filter-feeding bivalve, Mytilus edulis galloprovincialis L., cultured on rope collectors. The mussels effectively retained food particles larger than about 4 μm, and their retention rate increased with increase in plankton density between 10 5 and 5×10 6 cells ml −1, this being equal to the density of plankton in red tide water masses. Thus, plankton in red tide water masses should be removed rapidly from seawater by mussels through their retention and excretion, since the faeces excreted by mussels that had been fed on plankton were deposited speedily. Furthermore, the faeces excreted by mussels which contain a large amount of organic matter unabsorbed by the mussels, were eaten by an edible deposit-feeding sea cucumber, Stichopus japonicus. Thus, certain species of plankton concentrating in red tide water masses may serve not only as food sources for filter feeders and deposit feeders, but can also be removed from the seawater.