抄録
Interspecif is competition for space among sessile invertebrates was studied on panels exposed in four different seasons during a year in Tomioka Bay, south Japan. Development of the sessile community on the shaded faces of panels was monitored for 15 months. Competitive relationships between these species were strongly influenced by the timing of panel initiation. Hierarchical competitive relationships occurred on panels which were suspended in October 1991 (autumn), April 1992 (spring), and July 1992 (summer) and monitored until December 1992. On the other hand, network competitive relationship occurred on panels suspended in January 1992 (winter) and monitored until December 1992. After 5 months of panels suspension, a hierarchical relationship was observed on panels exposed in all seasons except winter, when a definite dominance among the organisms was not detected. The hierarchical position of a given species changed on panels initiated in different as well as the same seasons but observed after different time intervals. In general, colonial ascidians were dominant on all panels suspended except those initiated in January 1992 (winter). The patterns of colonization and species diversity on panels initiated in different seasons were different. Major factors responsible for these kinds of competitive relationships are timing of panel initiation, duration of panel submersion, pattern of initial colonization on panel surfaces, and seawater temperature.
