The Spatial Distribution, Growth, and Reproduction of the Bivalve Macoma calcarea (Gmelin, 1791) off the Novaya Zemlya Coast

Abstract

The population and biological characteristics of the bivalve mollusk Macoma calcarea (Gmelin, 1791) off the Novaya Zemlya Archipelago, eastern Barents Sea, are considered. The biomass of Macoma clams in the study area varied from 3.9 to 350.6 g/m2; the population density varied from 13.3 to 196.6 ind./m2. It was shown that the biomass and population density of clams do not depend on the depth and near-bottom water temperature; the size structures and growth rates were similar at different depths. The life span was found to differ significantly between clams that lived at depths shallower than 100 m (17 years) and deeper (26 years). At depths shallower than 100 m, aggregations of this species consisted mainly of juveniles (up to 4 mm); at the stations with greater depths, both juveniles and individuals with a shell length of 14.9 mm were found in abundance. Individuals of M. calcarea reach sexual maturity at an age of 3–4 yr, with a shell length of over 7.5 mm. At the stations with greater depths, there were significantly more mature clams than immature ones, and more males than females. Three stages of gametogenesis were identified in the examined females. The size of mature, ready to be spawned oocytes was 175 μm.