Three bopyrid isopods infesting the mud shrimp Upogebia major in the west coast of Korea (Crustacea: Peracarida: Isopoda)

초록

◎ Background of This Study : A dramatic increase in the population of the mud shrimp Upogebia major coincided with the recent collapse of the production of manila clam, Ruditapes philippinarum, in the west coast of Korea that had been stable during the last decade. In the course of the population dynamics studies of this critical ecosystem engineer, we found the mud shrimps significantly parasitized by the bopyrid isopods in some places of the Korean clam beds. Similar parasitism, a bopyrid isopod Orthione griffensis infected to its burrowing mud shrimp host Upogebia pugettensis has been reported in Willapa Bay from the west coast of the United States and intense infestations are associated with the apparent demise of many local populations of mud shrimp (Dumbauld et al. 2011; Chapman et al., 2012). ◎ Methods : Mud shrimps were collected at two sites around Seonjae-do tidal flat in Gyeonggi Bay and one site from Jugyo tidal flat around Dacheon River estuary in the west coast of Korea from January 2011 to October 2012. ◎ Results & Discussion : Of all 4,148 mud shrimps sampled in the west coast of Korea, infection rate presented about 14.2% bopyrid parasites. However, the infection rate of Jugyo population of the mud shrimp reached more than 80% in summer. We here report and describe three species of bopyrid isopods that were parasitic in the branchial chambers of the mud shrimps collected monthly from the study sites; Gyge Ovalis (Shiino, 1937) male and Orthione griffensis(Markham, 1988), Procepon liuruiyui(An, Williams, and Yu 2009) are reported for the first time from Korea.