関東地方および周辺地域における外来種ミドリイガイの分布

抄録

The author checked on the occurrence of the exotic bivalve, green mussel (Perna viridis Linnaeus, 1758) around western coast of the Tokyo Bay, all over the Sagami Bay and the innermost area in Suruga Bay, central Japan. The surveys were carried out for 8 years, from 2001 to 2013. The mussels have been found at seven to nineteen stations of fourteen to forty-one stations, where the mussels lived in intertidal to subtidal zones. The occurrence ratio, the numbers of occurrence stations to that of investigated stations, varied from 0.34 (in the year 2001 and 2013) to 0.63 (2009). The occurrence stations of living mussels were mainly located at from the innermost to middle areas in Tokyo Bay, the mouth and the innermost areas in Sagami Bay and the innermost areas in Suruga Bay. In all stations with three exceptions, the mussels attached to the artificial substrata such as the concrete seawalls, the buoys, the fixed nets and ropes. With reference of previous study, it was conjectured that the mussels which arrived at near northern limit of their global distribution lay themselves on the almost lethal conditions of low temperature in every winter season.