Distribution of the Anthozoan Metridium senile fibriatum (Verril) on the Rocky Sublittoral of the Rimsky-Korsakov Islands, Sea of Japan

The distribution of the anthozoan Metridium senile fibriatum on the rocky sublittoral of the Rimsky-Korsakov Islands at depths of 2–15 m has been investigated in relation to abiotic environmental factors. Together with the bivalve Crenomytilus grayanus, M. senile fibriatum dominates on rocky grounds in the upper sublittoral zone of open seaward coasts in the southern part of Peter the Great Bay. There is a significant dependence of its distribution on the intensity of water exchange and the bottom slope. The largest aggregations of M. senile fibriatum are found at depths over 10 m on vertical walls located at an acute angle or parallel to the prevailing directions of wave flows and in shallow gaping crevices with a stable direction of water flows. Anthozoans are absent from the rough rocky surface of the upper 5-m horizon and from relatively smooth walls exposed to wind waves at depths of less than 2 m. On the surfaces located at right angles to oncoming waves, the abundance of anthozoans drastically decreases.