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.

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.

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.

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.

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.