Vol 45, No 5 (2019)

For more than the past three decades, flow cytometry has been successfully applied in various, including phytoplankton, studies that require rapid qualitative assessment of the physiological condition, chemical composition, and number of microalgal cells. The potential of this method for solving applied and fundamental problems in microalgae research, the parameters of main fluorescent dyes used for this method, the features of microalgae as study objects, as well as the challenges associated with the use of the method, are discussed in the present review.

This paper reports the first data on the content of plant pigments in the upper bottom sediment layer of Aniva Bay (Sea of Okhotsk) located in the temperate-monsoon climatic zone. A positive relationship was found between the concentration of sedimentary chlorophyll a and its total content in the water column, which reflects a prevalent role of phytoplankton in the formation of the sedimentary pigment complex. A significant variability of the spatial distribution of the pigments in the bay is shown to be caused by the hydrological–hydrochemical parameters and characteristics of the bottom sediments. The contents of chlorophyll a and phaeopigments in sediments showed values of the oligotrophic category and averaged 6.5 ± 0.7 μg/g of dry sediment or 0.47 ± 0.06 mg/g of organic matter.

The peculiarities of infection with the parasitic bopyrid isopods Gyge ovalis and Progebiophilus sp. and the rhizocephalan Sacculina upogebiae among the mud shrimp Upogebia major population in Vostok Bay (Peter the Great Bay, Sea of Japan) were investigated in April–November 2017. Parasites were found from spring to late autumn. The prevalence of isopod infection in U. major was 5.42%, females and males were equally infected. The prevalence of Sacculina upogebiae was 1.26%; this parasite was more common on the female hosts. Isopods were found on mud shrimp larger than 42 mm; rhizocephalan externae occurred in individuals larger than 57 mm. The highest prevalence of parasites was observed in the summer (7.44%). No cases of simultaneous infection with different species of parasites were noted in U. major.

Data on age of the walleye pollock Theragra chalcogramma (Pallas, 1814) from the eastern Sea of Okhotsk, determined by otolith analysis, are considered. A comparison of the age–length relationships, as inferred from variations in modal body size of fish of strong year-classes and from otolith-based age estimates, has shown no significant differences. This confirms the accuracy of the otolith-based estimates of walleye pollock age.

The members of the family Gobiidae are usually small, secretive and are often overlooked in scientific studies of coastal marine communities. This family comprises the subfamilies of Sicydiinae, Gobionellinae, Oxudercinae, Amblyopinae, and Gobiinae. The Oxudercinae, Amblyopinae, and Gobiinae inhabit intertidal and subtidal zones of southern Iran. Stonogobiops nematodes has been identified in the study area for the first time. This research presents molecular reconstructions of seven goby species from the Persian Gulf and the Gulf of Makran, using the nuclear Rag1 and Rhodopsin genes. The phylogeny combines sequences of 51 species from GenBank with those of the new species. Maximum likelihood and Bayesian analysis were used to determine that the monophyly of the Oxudercinae and Amblyopinae, as suggested by previous morphological studies, cannot be supported by the present and other molecular studies. The subfamily Gobiinae contains Gobiopsis and Cryptocentrus lineages. Close phylogenetic relationships between Istigobius and Exyrias, and Stonogobiops and Cryptocentrus are verified by morphological and molecular examination. The present molecular reconstruction uses gobies from southern Iranian waters to present more precise phylogenetic relationships among the Gobiidae than have been presented in previous studies.

Carcasses of northern fur seal pups, Callorhinus ursinus, collected from the rookeries of Bering Island (n = 133), were examined for hookworms Uncinaria spp. The parasite was found in 90% of the pups from the Severo-Zapadnoe rookery and in 45% of the pups from the Severnoe rookery. This difference in prevalence of nematode infection between the rookeries is associated with the type of substrate, as well as with the pattern of distribution of the seal reproductive groups on each of the rookeries.