Distribution of intertidal sea anemones in Mutsu Bay, northern Japan

Abstract

The distribution of sea anemones on the rocky intertidal zone at 12 stations in Mutsu Bay and at 7 stations at a 5-km scale was investigated. Seven species of sea anemone were noted at sampling stations: Anthopleura japonica, A. fuscoviridis, A. pacifica, A. atodai, Cnidopus japonicus, Haliplanella lineata, and Actinia equina. In Anthopleura, the appearance frequencies of A. japonica (spawner) were higher than those of other anemones that occurred at each station, while A. atodai (brooder) showed a limited distribution. C. japonicus, C. japonicus, and A. equina were very rare. Sea anemones and sympatric benthic organisms occurred at the same stations, and no significant relationship between the number of sea anemones and the coverages of mussels which might be strong competitors for space was found. We show that the reproductive mode and sympatric organisms of sea anemones may be included among the factors that determine the distribution of sea anemones in Mutsu Bay, Japan. However, we need to further examine the environmental factors in this area, as well as intra- and interspecific relationships among anemones.