Examination of white blood cell indicators for three different ploidy level sturgeon species reared in an indoor recirculation aquaculture system for one year

Functional diploid Acipenser ruthenus, functional tetraploid Acipenser gueldenstaedtii and functional hexaploid Acipenser brevirostrum juveniles were sampled monthly for one year, and the white blood cell indicators were determined. The total number of leukocytes (TL) was 40.93 ± 17.24 × 10⁹/l for the diploids, 20.63 ± 11.20 × 10⁹/l for the tetraploids, 14.13 ± 7.72 × 10⁹/l for the hexaploids. The TL decreased with an increasing ploidy level. The highest number of leukocytes was reached during September and October for A. ruthenus and A. brevirostrum, from October to January for A. gueldenstaedtii (a statistically significant finding). The lymphocytes dominated (76.89–80.14%) in the differential counts and were found to be reduced in June and July in each group. Granulocytes were represented by neutrophils and eosinophils. Counting from all the leukocytes, the neutrophils represented 13.0–18.7% and eosinophils represented 5.7–6.1%. Increasing number of nuclear segments in the granulocytes was dependent on the increasing ploidy level. Nuclear segmentation in the lymphocytes was a common finding in higher ploidy level groups. The data suggest a significant effect of ploidy level on the total number of leukocytes and morphological nuclear changes in the granulocytes and lymphocytes. The seasonal variation in the differential leukocyte counts depends on the species and the influence of various external conditions rather than the ploidy level.

Study of the properties of the ovarian fluid of the Russian sturgeon (Acipenser gueldenstaedtii Brandt, 1833) during freezing

The process of freezing the ovarian fluid of the Russian sturgeon (Acipenser gueldenstaedtii Brandt, 1833) was analyzed. With gradual cooling from 22°C to -196°C at a rate of 10° per minute, the process of freezing, formation and change of ice microparticles was observed. The ovarian liquid was glazed at -5°C and only at -70°. With the microparticles of ice began to form. From that moment, up to the temperature of liquid nitrogen (-196°C), the microparticles were crushed into smaller ones. The high content of intracellular water in the ovarian fluid of female Russian sturgeon contributes to the formation of the bulk of microparticles of ice, which is confirmed by their shape. These particles, which have sharp edges, are able to damage the thin shells of eggs during deep freezing.

Interspecific hybridization in natural sturgeon populations of the Eastern Black Sea: the consequence of drastic population decline?

The eastern part of the Black Sea and its tributaries are suitable habitats for several sturgeon species, among which Acipenser gueldenstaedtii, A. stellatus, A. nudiventris, A. persicus, A. sturio, and H. huso are well documented. However, different threats have led these species to a dramatic decline, all of them are currently listed as Critically Endangered, and some Locally Extinct, in that area. We tested 94 wild sturgeon samples from the Black Sea and Rioni River by analyzing the mitochondrial Control Region and nuclear markers for hybrid identification. The data analyses (1) assessed mitochondrial diversity among samples, (2) identified their species, as well as (3) indicated instances of hybridization. The data collected, besides confirming a sharp decrease of catches of Beluga and Stellate sturgeon in recent years, also revealed four juvenile hybrids between Russian and Stellate sturgeon, providing the first evidence of natural interspecific hybridization in the Rioni. The present communication raises concerns about the status of sturgeon species in this area and underlines the urgent need for conservation programs to restore self-sustaining populations.

COEFFICIENTS OF ACCUMULATING CHEMICAL ELEMENTS IN ORGANS AND TISSUES OF RUSSIAN (ACIPENSER GUELDENSTAEDTII, BRANDT, 1833) AND PERSIAN (ACIPENSER PERSICUS, BORODIN, 1897) STURGEONS OF CASPIAN SEA

The article is focused on the possible ways of accumulating chemical elements (zinc, copper, chromium, nickel, lead, mercury) in the organs of aquatic organisms. In the course of the study, the coefficients of accumulating the chemical elements in the organs and tissues were calculated for the Russian (Acipenser gueldenstaedtii, Brandt, 1833) and Persian sturgeons (Acipenser persicus, Borodin, 1897) relative to the water of the northwestern part of the Caspian Sea, bottom sediments and the main objects of their food (Khvalyn goby (Neogobius caspius), Sandpiper goby (Neogobius fluviatilis), Caspian goblin (Benthophilus microcephalus), roach (Rutilus rutilus caspicus)). The studies were carried out according to the standard method of atomic absorption spectrometry. It is shown that the main source of accumulating the studied chemical elements in the organs and tissues of the Russian and Persian sturgeons is the water of the northwestern part of the Caspian Sea. It was found that the bottom sediments of the Caspian Sea act as an additional source of zinc and mercury found in the liver and kidneys of sturgeon species. Based on the calculated accumulation coefficients of chemical elements, there was revealed a predominantly alimentary nature of accumulating copper, nickel and mercury in the organs of both sturgeon species.

Ecological, Biological and Hematological Index of the Blood Analysis of Sturgeons (Acipenser) in the Caspian Sea

The Caspian is a unique drainless water body with no connection to the ocean. This study of the peculiarities of blood cell composition of the Russian sturgeon (Acipenser güldenstädtii) and sevruga (Acipenser stellatus) revealed minor destructive disorders of the blood cells. The number of blood cells also deviated from conditional norms. The study of the leukocyte profile of sturgeons showed the granular forms of leukocytes, band neutrophils and eosinophils, and segmentonuclear neutrophils and eosinophils. The total number of granulocytes in the blood of the Russian sturgeon was increased, which indicated the activation of the body’s protective systems in response to the anthropogenic load. In cytomorphological terms, the destructive disorders were revealed. Such phenomena are associated with the ever-increasing anthropogenic load on the biocenoses of natural reservoirs. Summarizing the results, it can be concluded that the quantitative indicators of red blood in the Russian sturgeon (Acipenser gueldenstaedtii) and sevruga (Acipenser stellatus) caught off of the Dagestan coast of the Caspian Sea were reduced in the spring of 2018 compared to 2016, but were in the normal range given in the literature. The concentration of hemoglobin in the Russian sturgeon and sevruga in 2016 was 13% and 15% higher than in 2014, respectively. This phenomenon could be a measure to compensate for the lack of oxygen in various fish tissues and organs. Keywords: Russian sturgeon, red blood cells, lymphocytes, eosinophils, neutrophils, anisocytosis, cytolysis of red blood cells

Functional state of the organism of the hybrid Russian sturgeon × Siberian sturgeon (Acipenser gueldenstaedtii × Acipenser baerii) after winter in cages in Volga Delta

Two-year-olds (15 individuals) and five-year-olds (15 individuals) of the Russian sturgeon × Siberian sturgeon (Acipenser gueldenstaedtii × Acipenser baerii) hybrid, kept in net cages in the Volga delta, were studied after wintering in order to establish the functional state of the organism according to the complex of indicators of the erythron system and metabolism substances. The results of the performed study found that the erythron system in five-year-olds is characterized by a higher content of erythrocytes and blood hemoglobin (0.58 ± 0.01×10 12 l –1 and 64.98 ± 1.29 g/l, respectively), compared with two-year-olds (0.49 ± 0.02×10 12 l –1 and 64.98 ± 1.29 g/l, respectively).The serum iron content in both groups was the same. A higher content of total protein and albumin in the blood, as well as a greater activity of ALT were found in five-year-olds, compared with two-year-olds. Thus, the content of total protein and albumin in blood serum in five-year-olds was at the level of 48.23 ± 1.54 and 21.58 ± 2.34 g/l, respectively, and in two-year-olds — 32.42 ± 0.92 and 13,84 ± 0.61 g/l, respectively (p < 0.05). The activity of serum ALT in five-year-olds was 1.07 ± 0.06 μkat/l, and in two-year-olds — 0.85 ± 0.03 μkat/l (p < 0.01). Serum cholesterol in five-year-olds (3.94 ± 0.04 mmol/l) and two-year-olds (4.4 ± 0.08 mmol/l) did not differ significantly (p > 0.05). The content of serum triglycerides in five-year-olds (4.50 ± 0.49 mmol/l) and in two-year-olds (5.36 ± 0.45 mmol/l) did not differ significantly (p > 0.05). The study of carbohydrate metabolism revealed a pronounced variability in the glycemic index in the younger age group (coefficient of variation 44.7 %) with an average blood glucose value of 2.69 ± 0.31 mmol/l. The blood glucose content of five-year-olds was higher than that of two-year-olds — 3.84 ± 0.24 mmol/l (p < 0.05). The established parameters of variation and the age specificity of the indicators of the erythron system, protein, lipid and carbohydrate metabolism can be used to assess the state of physiological adaptation of the hybrid after wintering in cages in the Volga delta.