Abstract
Changes during a 10-year period in distributional patterns of 24 polychaete species belonging to eight families [Glyceridae, Sigalionidae (Pisione and Pisionella), Pilargidae, Nereididae, Amphinomidae, Scalibregmatidae, Sternaspidae, and Pectinariidae] were described based on quantitative data by grab-samplings at 92 or 88 fixed subtidal stations in the Ariake Sea, western Kyushu, Japan in June in 1997, 2002, and 2007. The distributional pattern of each species was categorized into the following seven types: I) occurrence in all of six areas of the Ariake Sea (6 spp.), II) occurrence in five areas excluding the mouth part (1 sp.), III) occurrence mostly in four areas from the inner-south to mouth parts (2 spp.), IV) occurrence in three areas of the inner-south, center-east, and center-west parts (1 sp.), V) occurrence mostly in three areas of Isahaya bay, innermost, and center-east parts (1 sp.), VI) occurrence mostly in the mouth part (5 spp.), and VII) few appearances of up to three sites in each year (8 spp.). The mode of the temporal change in the distributional range and density was variable even among species belonging to the same distributional type. The ranges and densities of several species including some rare species extremely decreased from 2002 to 2007.
