Abstract

Polydora spp., which bores and burrows into the shells of bivalves may inhibit the growth and/or increase the mortality of commercially important shellfish, Crassostrea gigas. The purpose of this study was to examine the changes of commercial value and cellular immunological function in Pacific oyster, C. gigas according to the Polydora spp. infestation grade. The condition index was decreased with higher infestation grade. In cellular immune response analysis, phagocytosis was increased with higher infestation grade although there were no significant differences in adhesion and viability. In conclusion, infestation by Polydora spp. could be an indirect factor if accompanied by disease and/or environmental contamination rather than directly related to the death of oyster.