Impact of Water Quality Variation on Mussel (Mytilus galloprovincialis) Biomass in Semi-enclosed Port

摘要

There are many colonies of Mytilus galloprovincialis (mussel) on submerging vertical seawall in Amagasaki Port, which is a semienclosed eutrophied port in the Osaka Bay, Japan. This study focuses on water quality threshold and generation mechanism which induce mussel drop-off. According to field observations, it were found that water depth of occurrence of mussel dropping was not same at each observation stations, the mussel drop-off was occurred only in the observation stations where water temperature deviation maximum value was more than 2.5 °C, and the mussel drop-off occurred when an internal seiche was developed.