1. Marine Biosystems Research Center, Chiba University, Kamogawa, Chiba 299-5502
2. Department of Systems Engineering, Shizuoka University, Hamamatsu, Shizuoka 432-8561
3. Aihara Complexity Modelling Project, ERATO, JST, 3-23-5-201 Uehara, Shibuya-ku, Tokyo 151-0064
4. Institute of Industrial Science, University of Tokyo, Meguro-ku, Tokyo 153-8505
5. Department of Environmental and Forest Biology, State University of New York College of Environmental Science and Forestry, Syracuse, NY 13210, U.S.A.