The Biochemical Composition and Caloric Content of the Macrozoobenthos of the Western Kamchatka Shelf

Data on the biochemical composition and caloric content of common species of the zoobenthos of the western Kamchatka shelf were estimated for the entire body of an organism together with the integument and separately for muscle tissue. Estimates of the gross biomass of zoobenthos at different trophic levels calculated from bottom trawl and dredge sampling data, taking the isotope composition of benthic invertebrates into account, showed that the proportion of zoobenthos at the second trophic level was approximately 87%, while at the subsequent trophic levels it only slightly exceeded 13%. More than 70% of the energy was concentrated in valuable forage species. The total amount of energy at the second trophic level was 77.8%, while at the third and fourth levels it was 22.2%.     

Seasonal Dynamics of Plankton in Zones with Different Thermal Structures of Water off the Southern Kuril Islands

Based on plankton samples collected from 100–0 m depths in the years 1979–1980, the duration of biological seasons was determined and the seasonal succession of plankton was followed in five surface water modification zones: Kuril, Subarctic, Subtropical transformed, Oyashio (cold), and Soya (warm). The bloom of phytoplankton off the southern Kuril Islands begins in the months March–May and continues until June in waters of warm currents and until September in cold waters. Succession rates vary among the zones. In cold-water zones, the change in the plankton community from the spring to the summer state occurs about half a month later than in warm waters. The reason for this lag is the slower sea surface heating and the later stratification in cold-water zones.     

Diet and some ecological features of the most widespread commercial crab species in the northwestern Sea of Japan in early spring

Results of the study of feeding habits of the commercial crab species Chionoecetes opilio, Ch. japonicus, Paralithodes platypus, P. camtschaticus, and Erimacrus isenbeckii in early spring 2009 are presented. The composition, distribution, and quantitative characteristics of benthos in the areas of sampling are analyzed. The generalized pattern of distribution of the considered crabs is shown with the maximum and mean densities. These crabs were found to consume at least three to four single portions of food during 10–12 hours of daylight. The lowest feeding intensity was observed in the opilio snow crab in March and April. Cannibalism proved to be typical for all the studied crab species in the spring. It was most developed in the deepwater red snow crab, in whose diet representatives of the same species constituted a one-third share. It was also noted that the diet of the studied crabs included a major proportion of crabs and shrimps, which was unusual for the feeding habits of the same species in other Far Eastern seas.