Comparative Aspects of the Study of Morphophysiological and Biochemical Parameters of Somatic Growth in Populations of Two Species of Black Sea Bivalvia Mollusks: Cerastoderma glaucum and Flexopecten glaber ponticus

Abstract

The results of an analysis of the morphophysiological and biochemical indicators of somatic growth in Black Sea bivalve mollusks, the cockle Cerastoderma glaucum (Bruguiere, 1789) and the scallop Flexopecten glaber ponticus (Bucguoy, Dautzenberg et Dollfus, 1889), living in the vicinity of Sevastopol, are presented. The examples are of three size-age groups in the length range from 12 to 30 mm for both species; the features of tissue biosynthesis (somatic growth) of soft tissues are studied. According to the total RNA content and the RNA/DNA index in the C. glaucum, it is shown that, in the 17–22 and 23–28 mm groups (age 2–3 years), the level of synthesis of protein structures is 1.3–1.7 times higher than in the underyearlings. In individuals of F. glaber ponticus with linear sizes of 13–17 and 21–24 mm (underyearlings), the level of synthesis of protein structures is 1.2–1.5 times higher than in larger individuals (age 2 years). The species specificity of somatic growth is most significantly manifested in the middle and older size groups of the studied mollusks. The values of biochemical growth parameters in both species indicates an average level of tissue growth in comparison with other previously obtained data for the mass Black Sea bivalves. Linear regression models of size–weight values show that, for both species, the change in size explains 62–86% of the variation in body weight of the mollusk. An analysis of weight parameters (total mass/soft tissue mass) indicates a positive allometry of somatic tissue growth.