Russian Journal of Marine Biology最新文献

Abstract

New data have been obtained on the distribution of prokaryotic plankton and pelagic viruses in the Fram Strait (the Greenland Sea) during the polar night (late November). Three main types of water masses were present in the study area: surface polar, Atlantic, and transformed Atlantic. The content of mineral biogenic elements increased with depth. The concentration of chlorophyll a had low values (0.07–0.13 mg/m³). The abundance and biomass of prokaryotes varied from 286 000 to 675 000 cells/mL and from 2.7 to 11.7 mg C/m³, respectively. The composition of prokaryotic plankton was dominated by single small cells (more than 97% of the abundance and more than 68% of the biomass). The average cell volume was 0.034–0.096 μm³. The number of viruses varied from 724 000 to 3 920 000 particles/mL, and the biomass varied from 0.040 to 0.216 μg C/m³. Against the background of local maxima in the abundance of prokaryotic plankton in the 0–25 m layer, the highest concentrations of viruses were noted in the surface layer. In the latitudinal distribution (from south to north), an increase in the number of viruses and prokaryotes was revealed. A close relationship between their abundance and biomass with hydrological parameters and phosphate content was established; the role of certain water masses in the vertical distribution of microbes was insignificant. The relatively high abundance of viruses and prokaryotes indicated their significant activity during the polar night.

Abstract

This study elaborates the preliminary information on the meiofaunal assemblage pattern in the Krossfjorden system of the Svalbard Archipelago based on the samples collected during the Summer Phase Indian Arctic Expeditions of 2017 and 2018. The results from the study divulged the meiofaunal assemblage pattern. It is diversified with the presence of ten meiofaunal groups represented by Foraminifera, Tintinnida, Nematoda, Polychaeta, Copepoda, Kinorhyncha, Tanaidacea, Ostracoda, Acarina and Priapulida larvae. Meiofaunal abundance was observed to be low during the year 2018 (5646 ± 874 ind./10 cm²) compared with previous reports from adjacent fjord systems and the samples collected during the 2017 study (8826 ± 1501 ind./10 cm²). The decrease in meiofaunal assemblage in the fjord is associated with changes in environmental constraints and organic matter availability. The diminishing sea ice habitats in the Arctic waters are expected to have pronounced impacts on meiofaunal communities and their appearances in the coming future. In this regard, data gathered during the present study will form a baseline information on meiofaunal communities in the Krossfjorden system for understanding future changes in the benthic habitat and have important implications on predicting the direction of change with regard to meiobenthic productivity.

Abstract

In July–August 2022, the spatial distribution and the composition of local settlements of the bivalve mollusc Mya japonica Jay, 1857 in the Vostok Bay (Peter the Great Bay of the Sea of Japan) were studied. M. japonica occurred almost throughout the entire bay in a wide range of depths from 0 to 22 m at water temperatures from –1.9 to 25°С and salinity from 0 to 34‰. M. japonica was the most abundant in the shallow areas of the bays, closed from the direct wave impact, where, at a depth of up to 4–5 m, the density of the mollusc reached 27 ind./m², and the biomass was almost 4 kg/m², which averaged 56% of the total macrozoobenthos biomass. With increasing depth and moving from the dead-end of the bay to the open sea, the abundance of M. japonica decreased by one or two orders of magnitude. Local settlements differed significantly in size and age composition, size-frequency distribution of molluscs, indicating the nature of the replenishment of the benthic population with juveniles, as well as the proportion of commercial size individuals, which ranged from 37 to 98%. The reasons for the revealed features of the distribution and structure of the population of M. japonica are discussed.

Abstract

The torquaratorid enteropneust Quatuoralisia malakhovi Ezhova et Lukinykh in Ezhova, Lukinykh, Galkin, Krylova, et Gebruk, 2022 has been known only by the type material from the bathyal zone at depths of 1957–2289 m on the slopes of the submarine Piip Volcano in the Volcanologists Massif, southwestern Bering Sea. In this study, fragments of soft-bodied animals were obtained among trawled material from the bathyal zone in the Japan Trench, about 41.51° N, 144.13° E, at depths of 1987–2007 m during the cruise KH-22-8 of the R/V Hakuho-maru in October 2022. Partial sequences of the mitochondrial 16S rRNA gene from two fragments showed a 100% match with the ones determined from the type series of Q. malakhovi, suggesting conspecificity among them. This study broadens the known geographic distribution range of Q. malakhovi by ~2500 km southwestward. This is also the first record of the species as well as the family Torquaratoridae from Japanese waters. In total, the Hakuho-maru cruise KH-22-8 yielded four species of acorn worms in the Japan Trench (all represented by body fragments), including Q. malakhovi and two unidentified species in the family Harrimaniidae (briefly reported in this paper, about 40.80° N, 144.51° E, 6800 m, and 40.70° N, 144.68° E, 7000 m) in addition to Stereobalanus sp. (previously reported in another paper, about 40.80° N, 144.65° E, 7400 m). The phylogenetic positions of the two unidentified harrimaniids are inferred based on partial sequences of the 16S rRNA gene.

This article has been retracted. Please see the Retraction Notice for more detail: https://doi.org/10.1134/S1063074023330015

Abstract

A systematic analysis of the species composition of the prey of killer whale Orcinus orca Linnaeus, 1758 was carried out. The results of observations of killer whales hunting for different types of prey and the data from an analysis of the contents of their stomachs were summarized; the species affiliation of the prey was compared with the affiliation of predators to the R- or T-type based on a genetic analysis. It has been shown that killer whales of the Far Eastern seas of Russia have a pronounced foraging specialization, which correlates with the haplotype of the mitochondrial DNA control region. Killer whales with the NT1 and GAT haplotypes previously described for mammal-eating T-type killer whales from the northeast Pacific (also called Bigg’s killer whales) have been observed preying on marine mammals but not on fish. Killer whales with the SR haplotype, previously described for fish-eating R-type killer whales from the northeastern Pacific, preyed only on fish. Two new T-type killer whale haplotypes have been discovered; animals with these haplotypes have been observed preying on large baleen whales. The importance of traditions and social learning in the differentiation of ecological niches in cetaceans has been noted. The specialization to hunt certain prey transmitted from mother to calves allows killer whales of different ecotypes to avoid food competition and acquire morphological and behavioral adaptations that facilitate hunting for a particular type of prey.

Abstract

The influence of the average annual sea surface temperature (SST) on the development of the horse mackerel Trachurus mediterraneus on the southwestern Crimean shelf has been shown. The changes in the main indicators of the population and their relationship with the change in the average annual SST (0.055°С/year) in 2000–2020 have been identified. Against the background of the observed increase in SST in recent years, the state of the horse mackerel population has improved: there has been an increase in the average age and, accordingly, the proportion of larger well-fed individuals, and, in general, the average size and weight of fish. It has been shown that according to the nature of the change in the average annual SST, three periods can be distinguished: 2000−2007, 2008−2013, and 2014−2020.