Marine Biological Journal

Variability of the black scorpionfish, Scorpaena porcus Linnaeus, 1758 (Scorpaenidae), from two Black Sea localities

2023-02-17T08:49:53+00:00

Comparative investigation of morphological variability of the black scorpionfish, Scorpaena porcus Linnaeus, 1758, from two distant Black Sea localities – Foros village (Crimean Peninsula) and Malyi Utrish village (Krasnodar Kray) – was carried out. Due to sexual dimorphism in the black scorpionfish and small abundance of males in the samples, only mature females were analyzed. A total of 54 individuals were examined (29 from Foros and 25 from Malyi Utrish). We used 5 meristic and 26 morphometric characters. In the meristic characters, there were no region-related differences between black scorpionfish females from Foros and Malyi Utrish; in the morphometric characters (maximum body height, length of the first dorsal fin, distance between pectoral and abdominal fin, length of snout, eye diameter, and length of lower jaw), the differences were statistically significant. The canonical discriminant analysis showed that S. porcus females from Foros were correctly classified with an accuracy of 97%, while females from Malyi Utrish – with an accuracy of 100%. It was suggested that the obtained results are a manifestation of modification variability. However, there were no significant differences between black scorpionfish females from two localities in the total length and body mass, which could result from differences in trophic conditions and fish abundance. This may indicate the existence of a complex of modification and interpopulation variability in S. porcus from the investigated Black Sea localities. Though black scorpionfish pelagic eggs can be transported via sea currents, spatial isolation and limited migrations may lead to the formation of local populations of S. porcus. Nevertheless, analysis of genetic markers is required to test the hypothesis.

Finding of the golden goby Gobius xanthocephalus (Gobiidae) off the southeastern coast of Crimea (the Black Sea)

2023-02-17T07:36:00+00:00

Information is given on the finding of the golden goby Gobius xanthocephalus Heymer & Zander, 1992 (Gobiidae, Perciformes) off the southeastern coast of Crimea (the Black Sea), where this species was not previously recorded. An individual was registered during underwater ichthyological studies in the Dvuyakornaya Bay water area, in the vicinity of the northeastern tip of the Kiik-Atlama Peninsula (44°57′N, 35°23′E). The golden goby was recorded at a depth of 8.5 m at the foot of the underwater part of the rocky slope, in a shaded niche among a cluster of boulders. The finding of this species in the Southeastern Crimea indicates the expansion of its range in polyhaline water areas of the northern Black Sea.

On the 90th anniversary of Professor Oleg Mironov (1933–2022)

2023-05-29T12:17:40+00:00

9 March, 2023, marks the 90^th anniversary of the birth of D. Sc., Prof. Oleg Mironov. He organized the first marine sanitary hydrobiology laboratory in the USSR and became the author of more than 400 scientific publications.

On the 80th anniversary of Professor Yuriy Tokarev

2023-05-30T07:01:54+00:00

On 19 August, 2023, Yuriy Tokarev, IBSS deputy director for research and head of the biophysical ecology department, would have turned 80. He became the author of more than 260 publications and was an active participant in scientific expeditions.

Spatial-temporal dynamics of the zooplankton assemblage structure in coastal waters near Sevastopol in the spring–autumn period

2023-02-17T06:58:50+00:00

Zooplankton of the coastal water area near Sevastopol are quite well studied. However, there are few comprehensive investigations of local zooplankton assemblages involving the characterization of all the taxa forming them. Moreover, previous research was mainly based on material sampled in the Sevastopol Bay at only one or two stations – at the bay mouth and/or in its apex, and there was no analysis of zooplankton spatial variability within the bay. The aim of this work is to characterize the spatial-temporal dynamics of zooplankton communities in the Sevastopol Bay and the adjacent open coastal waters in the spring–autumn 2013. We analyzed zooplankton sampled in April–November 2013 in the western, central, and eastern Sevastopol Bay, as well as at three stations in the adjacent open coastal area: two miles from the Sevastopol Bay mouth, near the Uchkuevka village, and at the Kruglaya Bay mouth. To assess spatial-temporal differences in the taxonomic structure of zooplankton assemblages, we applied analysis of similarities (ANOSIM), used nonparametric multidimensional scaling (MDS), and determined the contribution of individual taxa to the Bray–Curtis dissimilarity between sample groups (SIMPER). When analyzing beta diversity, the Shannon index was applied. As revealed, during the study period, there were spatial-temporal differences in the abundance and taxonomic structure of zooplankton communities between various areas of the Sevastopol Bay and the adjacent open coastal waters. The highest degree of dissimilarity in the taxonomic structure of zooplankton was recorded between the central–eastern bay and the open coastal area. When comparing assemblages of these water areas, R values (ANOSIM) were 0.926, 0.572, and 0.761 (p < 0.03) in spring, summer, and autumn, respectively. The mean total abundance of zooplankton in the bay in all seasons was higher than in the open coastal water area: (5.3 ± 1.9), (16.3 ± 2.7), and (8.3 ± 1.4) thousand ind.·m⁻³ vs. (0.8 ± 0.3), (4.6 ± 1.2), and (3.4 ± 1.3) thousand ind.·m⁻³ in spring, summer, and autumn, respectively (mean ± SE; p < 0.006). There was a tendency towards higher density values in the central Sevastopol Bay. A change in the level of diversity and, accordingly, in the degree of complexity of zooplankton assemblage was revealed in the spatial-temporal aspect. In spring, the lowest level of diversity was registered, with a mean (± SE) value of the Shannon index H’ of 1.09 ± 0.16. In summer and autumn, the values increased to 1.94 ± 0.11 and 1.48 ± 0.09, respectively. In summer–autumn period, the values of H’ were higher in the open coastal area (2.07 ± 0.09) and lower in the inner water area (1.53 ± 0.09). As determined, the differences in the taxonomic structure between the communities of the compared water areas were driven by three dominant taxa in spring, nine in summer, and five in autumn.

Organic matter in the ecosystem of the Vladimir Bay (the Sea of Japan): Food resource and environmental risk factor

2023-02-17T08:25:25+00:00

To understand the accumulation process resulting from the input of toxic substances and elements into water areas, the study of the organic matter content in the aquatic environment and bottom sediments is of great importance. Moreover, such investigation is significant for identifying negative alterations in the ecosystem and potential environmental risks driven by the nature management. We aimed at analyzing the importance of organic matter as a factor of the environmental contamination in the Vladimir Bay (the Sea of Japan) and determining the toxicity of hydrobionts and the environmental risk to both the ecosystem and human health. This complex work was carried out applying chemical, analytical, microbiological, and hydrobiological techniques; it included mathematical and cartographic data processing, as well as calculation of accumulation factor and sediment quality guideline quotient. Seawater, bottom sediments, and macrobenthos sampled in the Vladimir Bay in July 2014 were analyzed. Chemical, ecological, and microbiological parameters of the bay waters were determined; those allowed to estimate the organic matter accumulation in the aquatic environment and bottom sediments and to establish the trophic status of the ecosystem in summer. Mass macrobenthic species and groups were identified; indices of benthic population abundance were determined indicating high levels of biomass. In surface waters, the abundance of heavy metal resistant groups of bacteria was estimated. In bottom sediments, heavy metal content and its spatial distribution were determined. Heavy metal concentrations in the sea urchin gonads were quantified. The results of the microbiological assessment were compared with maximum permissible concentrations (MPC), and a significant pollution of the bay waters (more than 3 MPC) in terms of Cd was revealed. For Ni, Cu, Zn, and Cd, background concentrations were exceeded in the bottom sediments; for Cd and Zn, clarke content was exceeded. The correlation between concentrations of organic matter in the bottom sediments and heavy metal content there was checked, as well as the correlation between heavy metal concentrations in the bottom sediments and in the sea urchin gonads (a statistically significant correlation was revealed for Zn). For the bay bottom sediments, the contamination factor C_f was determined; its values characterize the contamination with zinc as high, and with cadmium and copper – as very high. Also, the degree of contamination C_d was estimated; its values evidence for an average degree of contamination for the bottom sediments in total. The environmental risk quotients were calculated. According to SQG-Q value, the bay bottom sediments are classified as moderately polluted. As established, Cd and Pb content in the sea urchin gonads from the Vladimir Bay does not exceed the permissible values set in Technical Regulation of the Customs Union 021/2011. However, based on ILCR value, it can be concluded that there is a carcinogenic risk arising from consuming the sea urchin gonads.

Reproductive biology and the life cycle of the diatom Nitzschia cf. thermaloides inhabiting mud volcanoes of Crimea

2023-02-17T07:05:53+00:00

In biology, it is important to study the ability of organisms to exist under extreme conditions, to which the phase of the life cycle, related to sexual reproduction and the possibility to leave the next generation, is especially sensitive. Nitzschia cf. thermaloides Hustedt was found in high abundance in samples from puddles and lakes formed in the areas of action of mud volcanoes of the Bulganak mud volcano field (Kerch Peninsula, Crimea). Individual clones were isolated from the samples by the micropipette technique and introduced into a culture; their crossing made it possible to initiate heterothallic sexual reproduction. The aim of this work was to study reproductive biology and the life cycle of the alga from a biotope with extremely high levels of irradiance, temperature, and salinity. For the first time for this species, a description of the sexual process corresponding to IB2a type according to Geitler classification is given. The cardinal points have been defined, which represent critical cell sizes that determine the transition from one phase of the life cycle to another. The full range of cell sizes is given, from the initial ones that appeared as a result of sexual reproduction to the smallest ones observed when kept in the culture. The main postulates of the life-cycle theory are considered allowing to analyze the natural population of the alga. The population of N. cf. thermaloides was found to exist in the sampling site for a long time and to be represented by cells in all phases of the life cycle.

State of the ichthyo-, meso-, and macroplankton complexes off the Crimean Peninsula (the Black Sea) in connection with the hydrobiological regime features in October 2016

2023-02-17T06:36:29+00:00

The changes in the Black Sea hydrological regime recorded since 1990s have altered the state of epipelagic complexes of marine organisms, primarily the seasonal variability of their biological cycles. This largely affected the spawning phenology of natural fish populations, as well as ichthyoplankton species diversity and spatial distribution, and established trophic relationships within the plankton community. The interactions between links of the food chain in epipelagic complexes, as well as their seasonal and interannual variations, ultimately affect fish spawning efficiency, especially that of mass commercial species, and determine the replenishment of their new generations. To establish ichthyoplankton species composition, abundance, and spatial distribution, the study was carried out in shelf and open areas of the Black Sea (the Crimean coast) during the 89^th cruise of the RV “Professor Vodyanitsky” (30 September – 19 October, 2016). Eggs and larvae of fish and the biomass of meso- and macroplankton were analyzed. Ichthyoplankton and macroplankton were sampled with Bogorov–Rass net (inlet area of 0.5 m²; mesh size of 300 μm) by vertical sampling technique. In the shelf areas, sampling was carried out from the bottom up to the surface, while in the deep-sea areas, from the lower boundary of the oxygen zone up to the surface. Ichthyoplankton was fixed with 4% neutralized formaldehyde and investigated under microscope to determine taxonomic composition and, if possible, to analyze contents of fish larvae intestines. Species composition and spatial distribution of ichthyo-, meso-, and macroplankton in October 2016 were studied, as well as the feeding of fish larvae of the Black Sea off the Crimean coast. The research covered the initial phase of the autumn hydrological season. In samples, eggs and larvae of 9 warm-water fish species and 6 temperate-water fish species were found. The mean abundance of eggs was 2.92 ind.·m⁻², and the mean abundance of larvae was 3.56 ind.·m⁻². The low percentage (30%) of dead eggs of the warm-water European anchovy Engraulis encrasicolus and the presence of its different-sized larvae evidenced the ongoing productive spawning. The zooplankton biomass increased from the shelf towards the deep-sea areas. Small plankton organisms prevailed in the shelf areas providing enough food for fish larvae to survive. Despite the significant biomass of gelatinous plankton feeders in October 2016, their effect on ichthyoplankton complexes of the Black Sea was apparently minor.

Abundance, species diversity, and structure of the metazoan microzooplankton community in the bay–seaside gradient (on the example of the Sevastopol Bay)

2023-02-17T07:24:32+00:00

The aim of the research is to identify regular changes in the abundance, species diversity, and structure of metazoan microzooplankton (MM) communities under gradient conditions of the sea coast on a relatively small spatial scale. The relevance of the work lies in the paucity of such studies, which allow to assess indirectly the anthropogenic load (pollution, eutrophication) on marine biota and to apply species diversity indices to evaluate the trophic status of local water areas. The investigation covered three coastal areas of the city of Sevastopol: the open seaside, the mouth of the Sevastopol Bay, and its inner area. The localization of sampling stations reflects the gradient of environmental conditions, which is characterized by various degrees of the effect of natural and anthropogenic factors on the biota. The study was carried out in summer and autumn seasons. MM was sampled on three horizons of the water column: surface, 0–5-m, and 0–10-m layers. In the open seaside and the bay mouth, MM abundance along the vertical was characterized by a greater evenness; in the bay inner area, the differences between the layers could reach 5–700 times. Maximum MM abundance (1,837.1 thousand ind.·m⁻³) was registered in early August in the surface layer in the inner bay area. Since the late summer, the abundance decreased in all the studied water areas. The species diversity of the MM community, which was assessed applying the Shannon, Simpson, Pielou, and other indices, decreases from the open seashore towards the inner bay area. This pattern persisted in both seasons. The most informative indices were the Shannon, Simpson, and Pielou ones. Those reflected well both seasonal changes in species diversity and direction of changes in the trophic gradient of the local bay waters. Applying multivariate analysis, cases of significant alterations in the MM community structure were revealed for the bottom water layer in the inner bay area. The main probable cause of these local changes is the occurrence of hypoxic conditions in the lower water horizons of the polluted bay areas, which leads to the degradation of the abundance and species composition of the studied zooplankton community.

Assessment of antioxidant activity of seaweed extracts from the Sea of Japan in vitro and in vivo

2023-02-17T08:35:37+00:00

Seaweeds are a source of important biologically active substances: lipids, amino acids, phenolic compounds, polycarbohydrates, etc. Polyphenolic compounds are one of the perspective groups of constituents of marine origin with high antioxidant activity; those play a key role in the life of marine macrophytes, allowing them to quickly respond to external stress and to perform protective functions. At the same time, the multicomponent composition of the phenolic fraction of the seaweed extract provides a wide spectrum of its pharmacological activity, inter alia a regulatory effect on numerous homeostasis disorders occurring during pathological processes in humans and animals. Wherein, the available opportunities for the practical use of seaweed extracts have not yet been depleted, and this is of undoubted interest for modern science. The aim of the work was to carry out a comparative assessment of the antioxidant activity of hydroalcoholic extracts isolated from the thalli of three classes of algae [brown (Sargassum pallidum), green (Ulva lactuca), and red (Ahnfeltia fastigiata var. tobuchiensis)] and to analyze their effect on indices of the endogenous antioxidant system of liver and blood in mice under experimental stress. Seaweeds were sampled in summer in the coastal waters of the Peter the Great Bay (the Sea of Japan). Sampled seaweeds were dried at a temperature of about +50 °C, grinded in a laboratory mill to particles 0.5–1 mm in size, and extracted with 70% ethanol via repercolation. In the extract of the brown alga S. pallidum, the highest content of polyphenols was recorded – (218.2 ± 20.3) mg-Eq GA·g⁻¹ dry weight. In the extract of the green alga U. lactuca, the value was (16.2 ± 1.8) mg-Eq GA·g⁻¹ dry weight; in the extract of the red alga A. fastigiata var. tobuchiensis, (9.1 ± 1.6) mg-Eq GA·g⁻¹ dry weight. Accordingly, the antiradical activity of S. pallidum extract towards the cation radical ABTS⁺ and the alkyl peroxyl radical was significantly higher than that of U. lactuca and A. fastigiata var. tobuchiensis extracts. The effect of these seaweed extracts on the antioxidant defense indices of liver and plasma in mice under acute stress was studied experimentally. Weight indicators (weight of animals and weight coefficients of their internal organs) and biochemical indices (level of antiradical activity, malondialdehyde and reduced glutathione content, and activity of antioxidant enzymes) were established. The experiment was carried out on white outbred male mice (weight of 20–30 g). To model conditions of acute stress, mice were fixed vertically by the dorsal neck crease for 24 h. Alcohol-free seaweed extracts were injected into mice stomachs as an aqueous suspension (a dose of 100 mg of total polyphenols per kg of body weight) through a tube twice: right before vertical fixation and in 6 h. Into stomachs of the animals of the control and the “stress” groups, distilled water was injected in a volume equal to that of the injected extracts. In this model, all the attributes of stress manifested themselves: adrenal hypertrophy, involution of the thymus and spleen, and ulceration of the gastric and intestinal mucosa. Moreover, disturbances of the antioxidant defense system were recorded: a decrease of antioxidant enzymes activity in blood plasma, a drop in reduced glutathione content in liver, and an increase of the malondialdehyde level. Under the effect of the extracts, in all the groups of animals under stress, a tendency to stabilization of the studied antioxidant defense indices was observed. Interestingly, the values in mice receiving U. lactuca and A. fastigiata var. tobuchiensis extracts were inferior to those in the group of animals receiving S. pallidum extract. In the latter group of mice, there were no significant differences from the control values in terms of antioxidant defense indices. This is due to the fact the main components of the polyphenolic fractions of green and red algae are monomeric flavonoids, while brown algae contain high molecular weight phlorotannins. The latter ones are characterized by higher antioxidant activity than low molecular weight polyphenolic fractions of green and red algae.