Vol 49, No 4 (2023)

Labyrinthulomycetes are a small but very important group of marine fungi-like organisms. Labyrinthulomycetes are ubiquitous, can be associated with living plants, algae, and animals and can decompose a variety of organic remains. These organisms are able to synthesize and abundantly accumulate lipids, in particular, polyunsaturated fatty acids, some of which are of great interest for biotechnology. The scientific information about labyrinthulomycetes is currently accumulating very quickly. Our study is devoted to reviewing presently available data on the structure, biology and taxonomy of these organisms. The review examines the problems of methodological approaches to the study of these organisms, as well as the diversity, distribution and significance of Labyrinthulomycetes in marine ecosystems.

A comparative study of the composition of peripheral blood leukocytes of plunderfish and grey rockcod or squama caught in the Ross Sea has been carried out. Blood smears revealed cells of different morphofunctional characteristics and structure: lymphocytes, monocytes, neutro- and eosinophils, and blast cells. An analysis of the leukogram showed that the white blood of the studied species has a lymphoid character. In the rockcod leukogram, the proportion of lymphocytes is significantly higher, while that of monocytes and blast forms is lower. In the plunderfish, in comparison with grey rockcod, the leukocyte cells of the same name are usually larger.

The seasonal and interannual variability in the frequency of occurrence of the North Pacific common minke whale (Minke whale) Balaenoptera acutorostrata scammoni Deméré, 1986 off the north-eastern coast of Sakhalin Island (the Sea of Okhotsk) in 2008–2021 was studied. It has been shown that the occurrence of whales of this species in the study area has significant seasonal and interannual variability. The average frequency of occurrence in even years of observations was 1.6 times higher than in odd years and amounted to 7.1 and 4.4%, respectively. It has been suggested that the frequency of occurrence of minke whale in the study area is determined by the intensity of coastal wind upwelling off the eastern coast of Sakhalin Island.

We identified Gymnocanthus detrisus as the absolute dominant species in the taxocene of sculpins (family Cottidae), caught below 20 m water depth in the aquatic area between Cape Povorotny and Cape Mapatsa. Myoxocephalus polyacanthocephalus, Gymnocanthus herzensteini, Enophrys diceraus and Triglops pingelii are dominant as well. Subdominant species are Triglops septicus, Icelus cataphractus, Hemilepidotus gilberti, Myoxocephalus brandtii, Myoxocephalus jaok, Taurocottus bergii and Gymnocanthus pistilliger. Other types of fishes identified in this area are insignificant in abundance. Sculpins aggregate at greater depth in the southern aquatic areas, from Cape Povorotny to Olga Bay, and from Olga Bay to Cape Belkin, than in the northern areas, between Cape Belkin and Cape Zolotoy, particularly between Cape Zolotoi and Cape Mapatsa. We attribute this phenomenon to the differences in water regimes. The highest densities of sculpins are generally typical for the southern area. Conversely the lowest densities are typical in the northern area. However, some species prefer northern areas. The minimum depths habitat for different species varying from less than 20 m to 82 m; the maximum depths range from 80 to 530 m. Due to the high species diversity, aggregations of sculpins are observed in a wide bathymetric range from 20 to 300 m, with peak values at depths of 150–200 m. Sculpins live in summer at water temperatures above 0.4°C. The shallow water species of sculpins tolerate much greater temperature ranges then deep water species. Hence, the stenotherm increases in deep water species.

It was studied the influence of zinc and iron at concentrations of 50 and 100 µg/L on cell number, chlorophyll a fluorescence, content of photosynthetic pigments and reactive oxygen species, as well as neutral lipids in the raphidophyte algae Heterosigma akashiwo. Zinc has been found to act on physiological and biochemical processes without affecting the population dynamics of microalgae. It was revealed the negative effect of iron on the fluorescence of chlorophyll a, number of photosynthetic pigments, reactive oxygen species and neutral lipids. The most toxic metal for H. akashiwo turned out to be iron. It was shown that the concentrations of the studied metals do not contribute to the development of H. akashiwo “blooms”.