1. 1 Laboratory of Marine Biology and Coral Reef Studies, Faculty of Science University of the Ryukyus Nishihara Okinawa 903-0213 Japan
2. 4 E-mail: imai@sci.u-ryukyu.ac.jp
3. 2 National Research Institute of Fisheries Science Fisheries Research Agency Kanazawa-ku Yokohama 236-8648 Japan
4. 3 Tungkang Biotechnology Research Center Taiwan Fisheries Research Institute Pingtung 928 Taiwan