Питание и некоторые черты экологии крабов равношипого Lithodes aequispinus и угловатого Chionoecetes angulatus в водах северо-западной Камчатки в осенний период

Abstract

The behavior of animals, their population, distribution, rate of growth and maturation are determined mostly by the nature of nutrition. That’s why the knowledge of dietary habits and adaptations is necessary for a correct assessment of the food provision of animals, and it is an important link in the problem of population dynamics. This article is designated to fill data about golden king crab nutrition and to represent the first results of research of triangle tanner crab nutrition. The material for studying of food was the biological analysis of the gastrointestinal tract of 32 males of golden king crab and 143 males of triangle tanner crab obtained during a bottom trawl survey on the research vessel TINRO in the depth of 90–970 m in September and October 2012. The gastrointestinal tract was dissected and the food bolus of stomach and intestines was weighted, than the volumetric proportions of components were determined visually, the large fragments were weighted. The rate of occurrence of food objects, the prevalence rate and Froerman coefficient were also determined during analysis. Partial indices of stomach fullness were calculated as the percentage of each component in the food bolus. Partial indices of intestine fullness were not taken into consideration. The composition, distribution and quantitative characteristics of benthos in the areas of sampling were analyzed. An overall picture of the distribution of these crabs with indication of their maximum and average population density was submitted. It is noted that the basic food for golden king crab were the polychaete and brittle stars (33.2 and 32.1 % of the total mass respectively). The basic food for triangle tanner crab were the polychaete and molluscs (31.4 and 27.3 % respectively). The average fullness index was 15.5 and 20.9 ‱. It was concluded that both types of crabs are trophically associated with detrital network. Analysis of the data showed that food range of deep-sea crabs and offshore king crabs is determined by the composition of the benthic population in the habitat. It characterizes triangle tanner crab as the opportunistic omnivorous predator.