Abstract: The present invention provides a method for decreasing a sessile bivalve population in a body of water or a water conduit, comprising directing water containing sessile bivalve eggs, larvae, and/or mussels through one or more channels comprising one or more hydrophytes. Channels may be installed in front of a water supply pipe in order to decrease sessile bivalve infestation of the supply pipe.

Abstract: An optical disk apparatus is provided with an outer casing, a tray, a disk driving motor, holding claws, and bosses. The tray is movable in and out of the interior of the outer casing. An optical disk, which is either uncovered or contained in a cartridge, is placed on the tray for information processing. The disk driving motor, located inside the outer casing, rotates the optical disk when the optical disk is placed thereon and conveyed into the outer casing while being held on the tray. The holding claws are provided on the tray. When the outer casing is stood and the optical disk is uncovered, the holding claws hold the optical disk. The bosses retreat the holding claws in a direction away from the optical disk only when the optical disk held by the holding claws is fitted on the optical disk driving motor.