Vol. 49 No. 1, 2010

Effects of Anoxia on Immune Functions in the Surf Clam Mactra veneriformis

Jin-Ha Yu¹, Min-Chul Choi², Kyung-Il Park¹, and Sung-Woo Park^1,*

¹Department of Aquatic Life Medicine, Kunsan National University, Gunsan 573-701, Jeollabukdo, South Korea
²Incheon Fisheries Hatchery Research Institute, Yeongheung, Ongjin, Incheon 409-871, South Korea

Jin-Ha Yu, Min-Chul Choi, Kyung-Il Park, and Sung-Woo Park (2010) The surf clam Mactra veneriformis is one of the important fishery resources in Korea.  Its yields have recently been decreased due to environmental changes such as water levels, temperature, salinity, dissolved oxygen, pH, etc.  In particular, exposure to air during low tides may have been a contributing factor.  This study was carried out to examine the immune functions of the surf clam when it undergoes anoxic stress from air exposure for 24, 48, and 72 h.  Some of the air-exposed clams were also examined after recovering for 24 h in aerated seawater.  The total hemocyte count (THC), phagocytic activity, lysozyme activity, phenoloxidase (PO) activity, and nitroblue tetrazolium (NBT) reduction were assessed in both air-exposed and exposed-recovered groups.  Air exposure, regardless of the period, induced significant decreases in the THC, phagocytic rate, lysozyme activity, PO activity, and NBT reduction.  However, air exposure elicited no significant change in the THC.  Clams exposed for 24 h and returned to seawater had almost fully recovered within 24 h.  However, partial recovery was observed only in the THC and PO levels after 48 h of exposure followed by a 24 h recovery period.  The present study demonstrates that air-exposure-induced anoxia compromises immunological functions in M. veneriformis, and the effects cannot be ameliorated if the stress exceeds a certain point.

Key words: Mactra veneriformis, Surf clam, Immune function, Stress, Anoxia.

*Correspondence: Tel: 82-63-4691884.  Fax: 82-63-4691884.   E-mail:psw@kunsan.ac.kr