Preliminary Reconnaissance on the Benthic Communities of the Tanabe-wan

概要

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The benthic communities of the Tanabe-wan on the west coast of the Kii Peninsula were surveyed quantitatively in September to October, 1937. The collection was made by means of EKMAN'S bottom sampler for the marine use, with the unit square of 1/37 sq. m., and it closes automatically as it reaches the bottom. Polychaetes dominate in the faunal constituents, making up about 71% of the total animals, and the molluscs come next by about 19% (table 2). Two distinct communities were recognized in the benthic fauna. The Maldane-association (a polychaete community) occupies the muddy bottom near the mouth of the bay, almost all stations therein deeper than 20m (fig. 1). The commonest animal to be met with on the muddy area of the inner bay is Cerithium-the Cerithium-association (a snail community), and polychaetes such as Terebellides, Magelona and Sternaspis are associated with it. The depth range of this association is 4-17m. The faunae on shallow sandy or sandy-mud stations are very poor, and so far they appear to be community fragments. It is, however, possible that by a further survey they may turn out to be fasciations of some definite associations. The population density was the greatest in the Maldane-association, but in weight the Cerithium-association exceeded others, because it contains many shells.