Haematological parameters of Lake Baikal oilfish (golomyanka) (Comephorus dybowskii and Comephorus baicalensis)

Abstract

Two endemic Baikal species of oilfish, Comephorus dybowskii (“small golomyanka”) and Comephorou baicalensis (“big golomyanka”) live in the pelagic zone down to the bottom (1600 m). Both have numerous adaptations to the pelagic habitat. In this regard, the paper gives results of studies of blood under various natural conditions. The cell composition of peripheral blood does not differ between the species. Light and electron microscopy showed absence of granulation in polymorphic nuclear leukocytes. Significant differences in shape (number eccentricity) and sizes of mature erythrocytes were apparent. Parameters of red blood and cytometric indices do not change significantly within each species. However, high values of variation coefficient in the parameters of white blood were observed in both. Small golomyanka in comparison with big golomyanka have a higher percentage of erythroblasts, haemoglobin concentration and oxygen capacity of blood (OCB), while the percentage of polymorphic nuclear leukocytes and mature erythrocytes is less. Both species differ only insignificantly in number of erythrocytes, leukocytes, haemoglobin concentration in erythrocytes, index of leukocyte abundance, and thrombocytes per unit of blood volume. Small golomyanka caught at different depths do not differ much in most parameters of blood, but our analysis shows a high positive correlation between habitat depth, haemoglobin concentration and erythrocyte number per unit of blood volume. Blood characteristics indicate that small golomyanka is the more metabolically active species.