Polydorid species (Polychaeta: Spionidae) associated with mollusk shells around Japanese, Korean, and Chinese waters

초록

Species of Polydora and related genera are collectively called polydorids and many of them are widely known for their boring activities into various calcareous substrates. They often become harmful invaders by reducing the commercial value, growth rate and meat yield, or inducing mortality of commercially important mollusk shells. Until today, totally 13 polydorid shell borers and 11 non-borers have been described from Japanese waters. Particularly Polydora brevipalpa and P. uncinata were suggested to be the most harmful boring species inhabiting mollusk shells from the field of aquaculture. A total of seven species of genera Polydora, Dipolydora, and Boccardiella were collected from wild and cultural mollusk shells from the intertidal to subtidal in Korean waters. Polydora haswelli and P. aura were the most common and serious species observed to bore into mollusk shells. Polydora uncinata was suggested to have been transported with oysters introduced to the northeastern area. Boccardiella hamata was common observed to inhabit mud deposits in crevices of the oyster shells. Polydora onagawaensis and P. brevipalpa were the common borers around the waters of Shandong Peninsula, the northeastern China. There were some common polydorid species distributed along the coasts of Japan, Korea, and China. Boccardiella hamata was one of the most common non-borer species associated with oyster beds in these waters. We discuss the polydorid species from the viewpoint of aquaculture and unintentional transportation of alien species which are suggested to have been introduced with commercially important host shells.