Communities of macrozoobenthos on soft sediments in the coastal areas of open parts of Peter the Great Bay, Japan Sea and their ecological status

Abstract

At least 10 communities of macrozoobenthos are determined by modern statistical methods on soft sediments in the coastal areas of Peter the Great Bay with the depth of ≥ 5 m surveyed in 1992, 1993 and 1996. They were: I. Scoletoma spp. + Ophiura sarsii; II. Aphelochaeta pacifica (I–II — in the Strelok Bay and Rifovaya Inlet); III. O. sarsii +  Amphiodia fissa; IV. Scoletoma spp. + Mactra chinensis; V. Scoletoma spp. + Maldane sarsi; VI. Acila insignis (III–VI — in the Posyet Bay and adjacent area); VII. Scoletoma spp. + Echinocardium cordatum; VIII. Dipolydora cardalia + M. sarsi + O. sarsii; IX. Spiophanes uschakovi + E. cordatum, and X. Ampelisca macrocephala (VII–X — in the area at the Tumannaya/Tumen River  mouth). Their  development  was  determined  by  such  environmental  imperatives as the bottom sediments properties (silting degree, mean grain size), depth, and level of pollution and eutrophication. Majority of these communities (I, III, IV, V, VII, VIII, IX, and X) were in good ecological condition. Their habitats were slightly disturbed (intact or almost intact) and rare or never polluted and eutrophicated. The community II occupied more disturbed habitats with moderate ecological status reflected in higher indices of pollution. This community was rather likely formed in the process of succession in conditions of decreasing pollution. The community VI had a lower ecological status; its differentiation was probably caused by specific oceanographic regime of the Posyet Bay and anthropogenic impacts.