Ekaterina Sergeevna Miroshnichenko

Marine cyanobacteria represent a promising but underexplored bioresource for rare earth element (REE) management. This study investigated the effects of lanthanum (La, 10 mg L⁻¹) on four cyanobacterial strains isolated from Black Sea periphyton: Desertifilum tharense AqMaPh-IBSS-CYA-1, Toxifilum mysidocida AqMaPh-IBSS-CYA-10, Salileptolyngbya sp. IBSS-CYA-8, and Cyanobium sp. AqMaPh-IBSS-CYA-15. La induced a delayed hormetic response in Cyanobium sp. Under suboptimal light and temperature conditions, La supplementation supported 100% survival of all strains over 35 days, whereas controls perished. SEM-EDX indicated predominantly intracellular La localization, with surface-bound La detected only sporadically. ICP-MS revealed hyperaccumulation of La (9.5–13.3 mg g⁻¹ dry weight, 110–226-fold enrichment) and co-accumulation of light REEs in filamentous strains. Strain-specific responses suggest distinct protection mechanisms: T. mysidocida may employ metal efflux and polyphosphate granule sequestration, suggesting potential for REE recovery; Salileptolyngbya sp. appears to show broad-spectrum metal binding, potentially useful for bioremediation; D. tharense seems to be the most sensitive under the tested conditions, suggesting potential as a REE bioindicator. These findings are preliminary, but they suggest that La may act not only as a toxicant but also as a metabolic modulator, highlighting the potential of these cyanobacteria as bioresources for sustainable REE management.

The species Halamphora kolbei is a rarely reported diatom, and information on its distribution and characteristics is limited. The original taxonomic description of this species is inaccurate and insufficient for identification, as the available literature contains scarce and scattered data. In the present study, we summarised the available data on this species and provided a detailed description of the strain isolated from Sevastopol Bay of the Black Sea. Findings from a phylogenetic analysis of two genes, 18S rRNA and rbcL, are presented. The process of isolation, identification and establishment of a monoculture of the H. kolbei is described in detail. In addition, the productivity and biochemical characteristics were evaluated to assess the biotechnological potential of the strain. The growth rate, biomass productivity and protein, carbohydrate, lipid and fatty acid composition of this species were determined in this study, under controlled conditions. The high content of C14–C16 acids in H. kolbei has been revealed to make it a promising source of eicosapentaenoic acid. The detailed description of the species, its photographs and phylogeny, as well as additional morphological keys presented in the paper, will enable scientists around the world to study this species as a promising biological resource.

Bioaccumulation by diatoms, as the first stage of biomineralisation, has been widely studied for various metals, such as cadmium, copper, zinc, aluminium, gold, silver, etc. However, despite the fact that the mining and utilization of rare earth elements (REEs) are currently increasing, there is almost no data on their bioaccumulation by diatoms. Therefore, the aim of this study was to determine the ability of diatoms to bioaccumulate REEs by the example of lanthanum (La), and to compare this ability for two marine diatoms Nanofrustulum shiloi and Halamphora kolbei. As a result of experiments on the cultivation of diatoms in nutrient media supplemented with La at concentrations of 10 mg·L⁻¹ and 50 mg·L⁻¹, energy-dispersive X-ray spectroscopy revealed the ability of diatoms to bioadsorb La on their frustule surface, as a first stage of its bioaccumulation. The high concentration of La (50 mg·L⁻¹) has a noticeable visual effect on the morphofunctional state of diatoms and causes a decrease in the rate of accumulation. The low concentration (10 mg·L⁻¹) promotes the hyperaccumulation of La by the diatom biomass as a whole, including both bioadsorption and bioabsorption within the cells. This resulted in an increase in La concentration in the biomass by nearly 2000-fold in H. kolbei (6.06 mg·g⁻¹) and by 1000-fold in N. shiloi (6.90 mg·g⁻¹). The results on La bioaccumulation by diatoms are significant for advancing methods to remediate aquatic environments contaminated with rare earth elements and for the bioindication purposes.

Context: The influence of environmental factors on the quantitative characteristics and structure of cyanobacterial communities within marine microbial mats remains understudied. Aims: A comparative analysis of the community structure and seasonal dynamics of quantitative parameters of cyanobacteria in periphyton and epilithon in Karantinnaya Bay in the Black Sea, linking them to the environmental factors. Methods: The total number and biomass of cyanobacteria were quantified on the basis of established methods for the benthic cyanobacteria. Key results: The abundance and biomass of cyanobacteria were 0.38 × 106–4.20 × 106 cells cm−2 in periphyton and 0.004 × 106–0.158 × 106 cells cm−2 in epilithon, 0.0035–0.160 mg cm−2 in periphyton and 0.00002–0.004 mg cm−2 in epilithon. Maximum values were recorded in November for periphyton and August for epilithon; minimum values were recorded in March. Thin filamentous cyanobacteria are more responsible for changes in abundance, and biomass is determined by thick filamentous species, and in their absence, by unicellular cyanobacteria. Conclusions: Cyanobacterial communities in periphyton and epilithon differed in density, seasonal dynamics, dominant species composition and response to the nutrient contents. Nitrogen, phosphorus and their ratio at optimal pH were most important for cyanobacteria, but the requirements for certain nutrients varied between biotopes. Implications: This study will clarify microbial assemblages’ ecological roles in coastal ecosystems and their utility as sensitive biomonitoring indicators.

Rocky seabeds, as an integral part of ecotopes in marine ecosystems, are actively inhabited by diatoms and cyanobacteria. It is currently unknown whether the element contents in the surface layer of seabed rocks affect the epilithon species composition and abundance in microphytobenthos communities in the sea. The results of this study on the rock surface element composition and correlation analysis of the element contents with the abundance of epilithon diatoms and cyanobacteria in three bays in Sevastopol (Black Sea) are presented. Ca, Fe, and Si were the major elements with the largest weight fraction in the rock surface layer. Using cluster analysis, the differentiation of samples in the content and distribution of these three elements was shown. In total, 63 taxa of diatoms and 20 species of cyanobacteria were found, with their abundance ranging from 14,000 to 17,6000 cells/cm² and from 12,000 to 1,198,000 cells/cm², respectively. In general, it was found that the elemental composition of the rock surface is not a decisive factor affecting the total abundance of the benthic diatom and cyanobacterial communities as no strong correlations with any element contents were observed. However, when analyzing the abundance of populations of certain largely non-dominant species, the majority of diatoms showed noticeable (r = 0.5–0.7) to very high (r = 0.9–0.99) correlations with Fe. The highest positive correlations were noted for the diatoms Bacillaria paxillifer and Navicula directa with Fe. For the cyanobacteria Chroococcus minutus, Pseudanabaena minima, and Spirulina subsalsa, strong positive correlations with Ca and negative correlations with Si were observed. The correlations with Fe were very strong and negative for Lyngbya confervoides and strong and positive for Kamptonema laetevirens and Phormidium holdenii.

Analysis of long-term data (1987–2019) was carried out on the morphology and autecology of the benthic colonial large-cell species Striatella unipunctata (Lyngbye) C. A. Agardh, 1832 in the microphytobenthos of the Black Sea and Sea of Japan, including water areas of specially protected natural areas of Russia. The species is widely found on natural and artificial substrates in the Black Sea year-round, and in the Sea of Japan, at a water temperature down to −1.5 °C. St. unipunctata quantitative data were determined by direct cell counting in the Goryaev camera under light microscopes (LMs) Biolam L-212, Axioskop 40, and Olympus BX41. Species morphology, phytogeography, and ecology are described. The cell size range of populations is presented: for the Black Sea, valves 25–148 µm long, 8–22 µm wide, frustules 36.3–50.4 µm wide, 18–24 fibulae in 10 µm, and 7–8 girdle bands in 10 µm; for the Sea of Japan, valves 85–125 µm long, 12–21 µm wide, 7–8 girdle bands in 10 µm, 20–25 fibulae in 10 µm, frustules 32.0–34.3 µm long, 10–11 µm wide, and 25 fibulae in 10 µm. For the first time, St. unipunctata valves and frustules were studied in vivo under LMs, and frustule ultrastructure, under a scanning electron microscope (SEM). For the first time, quantitative indicators of the species populations from the Black Sea and Sea of Japan were compared. The morphology of the frustule ultrastructure of St. unipunctata was studied under a Hitachi SEM, model SU3500 (Japan), in Leica EM ACE200 gold-palladium-coated samples. In the Kazachya Bay of the Black Sea near the Oceanarium, the absolute maximum abundance was recorded – 41.6·10³ cells·cm−2 with a biomass of 1.73 mg·cm−2 in January (t = +6.9 °C) in the epizoon of the cultured mussel Mytilus galloprovincialis Lamarck, 1819 at a depth of 0.5 m at excessive organic pollution of water. The minimum values were of 0.26·10³ cells·cm−2 and 0.011 mg·cm−2, respectively, in July (t = +23.5 °C) at a depth of 2.5 m. In the Paris Bay (Russky Island) of the Sea of Japan in the water area of the Marine Mammal Research Base of the Primorsky Oceanarium (Vladivostok), the abundance in the asbestos plates periphyton was of 207·10³ cells·cm−2 in the summer. For the first time, unique micrographs of the species in vivo were obtained under a LM, and of purified frustules – under a SEM.

This article presents the results of studies of the cyanobacteria from foulings of natural and anthropogenic substrates of the intertidal zone of the Kola Bay of the Barents Sea for the period from 2010 to 2019. Ninety-five cyanobacterial species from 46 genera, 20 families, and 6 orders were found; 22 species are given for the first time for the Barents Sea. A majority of cyanobacterial taxa belong to benthic species (70%), which live mainly on natural substrates. The species abundance decreases from the lower intertidal zone to the supralittoral. The proportion of planktonic and bento-planktonic species was 12% and 18%, respectively. Freshwater (44%), marine (37%), brackish-water (3%), and euryhaline (16%) species have been found in the intertidal zone of the bay. The study has revealed 27 indicator species; most of them were oligo- and oligo-betamezosaprobionts. The cyanobacteria of the Kola Bay were predominantly boreal-tropical-notal (26%), cosmopolitan (23%), and boreal (18%) species. Peaks of the number of species were recorded in the early spring (March) and autumn (October). Areas with increased anthropogenic pressure from seaport cities showed the lowest index of species similarity.

Описан новый для крымского прибрежья Чёрного моря вид токсичной цианобактерии Microcystis wesenbergii (Komárek) Komárek ex Komárek, 2006, обнаруженный в результате исследования сообществ перифитона 45 образцов синтетических полимерных материалов из полиэтилентерефталата (PET), полиэтилена высокой плотности (HDPE) и полипропилена (PP), экспонированных в Карантинной бухте Чёрного моря в районе г. Севастополя (44°37′23.0″N, 33°29′38.5″E) в экспериментальной вертикальной установке с августа по сентябрь 2018 г., когда температура воды изменялась от +22,4 до +26,6 °C, а солёность воды — от 17 до 18 ‰. M. wesenbergii выявлен на глубине от 7,6 до 9,2 м на образцах из HDPE, PET зелёного цвета, PP и на фрагментах пластиковых контейнеров. M. wesenbergii — полиморфный, планктонный вид, который в небольших количествах встречается в стоячих и медленно текущих эвтрофных и мезотрофных пресноводных водоёмах; токсичен, иногда вызывает цветение; космополит, за исключением субполярных зон. Встречался в сложных колониях, которые состояли из субколоний, достигающих максимально 3700 мкм в длину. Диаметр молодых сферических колоний варьировал от 240 до 367 мкм. Диаметр клеток M. wesenbergii был больше диагноза [(10,19 ± 0,79) мкм], а цвет клеток — преимущественно светло-коричневым вместо сине-зелёного. Обнаружение токсичного M. wesenbergii в Карантинной бухте Чёрного моря свидетельствует о высоком скрытом разнообразии цианобактерий в этой акватории.