The literature data from the last decade on the chemical structures, distribution and functional peculiarities of the membrane and reserve lipids of marine macroalgae are summarized. A brief description of the prevalence of glycolipids, phospholipids, betaine lipids, sterols and triacylglycerols in various phyla of algae is provided. Particular attention is paid to the fundamental differences in the lipidome of green, red, and brown macroalgae. More than a hundred lipid molecular species identified by liquid chromatography–mass spectrometry are presented, and the relationship between the molecular composition of lipids and their role in the cell is discussed. The potential of lipidomic studies of marine macroalgae for the discovery of biologically active lipids and promising molecular markers of their physiological state is emphasized.
Shell lesion, commonly known as “shell disease”, is common in crustaceans, including commercial species. Based on a number of grounds, the integumentary diseases are classified into erosive and non-erosive forms. The erosive shell disease is found in red king crab as in both northeastern and northwestern Pacific Ocean, the Bering and Okhotsk Seas, as in the Barents Sea. A non-erosive form of shell disease was discovered in red king crab in the Barents Sea in 2016. It differs from the erosive shell disease and various non-erosive forms described in the available literature by clinical and histological features. Mass outbreaks of this disease were recorded in 2016 and 2023.
The thermogenesis activity of erythrocyte ecto-ATPase and its influence on the body temperature was studied in demersal fish: the thornback ray Raja clavata Linnaeus, 1758; the black scorpionfish Scorpaena porcus Linnaeus, 1758; the tub gurnard Chelidonichthys lucerna Linnaeus, 1758; and the Black Sea turbot Scophthalmus maeoticus Pallas, 1814. It was shown that erythrocyte suspensions from the thornback ray and the black scorpionfish, which have high ecto-ATPase activity, demonstrated a high capacity for heat generation during ATP addition. In contrast, erythrocytes of the tub gurnard and the Black Sea turbot, having low activity of the ecto-enzyme, demonstrated lower heat production under the same conditions. Thermograms of all studied fish species had similar dynamic profiles of temperature change in the erythrocyte suspension, which was termed a thermal jump. The fish species were subdivided into two pairs according to thermogenesis activity: the thornback ray and the black scorpionfish with high ecto-ATPase activity, and the tub gurnard and the Black Sea turbot with low enzyme activity. The observable effect of thermogenesis in fish with high erythrocyte ecto-ATPase activity was a higher body temperature. Juvenile thornback rays had a body temperature higher than the environment by 0.09°C, and mature individuals by 0.18°C. This difference is attributed to the lower heat loss of adult fish, which have a higher body mass compared to juveniles. The increase in body temperature was greater in the black scorpionfish than in the thornback ray juveniles, despite their similar body masses. This can be explained by the higher ecto-ATPase activity in scorpionfish and the lower rate of heat loss due to better thermal insulation resulting from a thick muscular “framework”. Erythrocytes with high ecto-ATPase activity are effective heat “generators” capable of maintaining a higher temperature in the blood flow, which is necessary for plasma membrane function and the overall bloodstream.
The Humboldt penguin is among the most popular penguin species exhibited in zoos and aquariums worldwide. Studying its reproductive characteristics in the wild is challenging due to both its biological traits and protected conservation status. Therefore, conducting such studies on captive populations is the most practical approach. Over 5 years, we studied the reproductive characteristics of a colony of this species at the Primorsky Aquarium using direct visual observations and CCTV recordings. The sex of the birds was determined using a simple DNA test based on amplification of the CHD1 gene. Between 2020 and 2024, the Humboldt penguin flock grew from 14 to 59 individuals and consisted of 31 males and 28 females. Pair formation was first observed when the colony reached 14 individuals with an equal sex ratio. Young pairs in their first reproductive year hatched an average of one chick, whereas experienced pairs (those breeding for more than 1 year) produced two to three chicks. Based on these results, recommendations were developed to enhance the breeding success of Humboldt penguins in captivity.
On July 14, 2025, the carcass of a male Hubbs’ beaked whale, Mesoplodon carlhubbsi Moore, 1963 (Ziphiidae), approximately 4.55 m long, was found in the surf zone on the southwestern coast of Sakhalin Island (48°00′11″ N and 142°11′15″ E). The whale had presumably died due to an injury inflicted by another male long before becoming stranded.
The seasonal dynamics of phytoplankton from May to October were studied in the estuarine areas of the spawning rivers Onenusi (2023) and Gorbusha (2024) in the southeastern part of the Tatar Strait. A high species diversity (447) was revealed, including new taxa for the Tatar Strait (Thalassiosira ordinaria Makarova, T. binata Fryxell, and T. pacifica Gran et Angst) and for the seas of Russia (T. kushirensis Takano). The main similarity between both study areas was the sharp spatial heterogeneity associated with the geomorphology of the region. Maximum biomass values (up to 40 g/m3 in the Onenusi River area and up to 15 g/m3 in the Gorbusha River area) were confined to a narrow strip near the water’s edge, where diatoms of the genus Thalassiosira dominated. In the offshore part (at a depth of 5–20 m), the biomass was an order of magnitude lower, but the taxonomic diversity, due to pelagic species, was higher. The main difference was evident in the nature of the seasonal dynamics, determined by meteorological conditions. In the relatively calm year of 2023, a series of intense biomass peaks (up to 3.87 g/m3 on average) were observed near the Onenusi River. These peaks were observed in the second 10-day period of May, the first and third 10-day periods of June, and the third 10-day period of July and were caused by a prolonged diatom bloom. In 2024, characterized by stormier conditions, near the Gorbusha River, the total biomass was lower (up to 1.77 g/m3), and its dynamics were described by a two-peaked curve, with peaks in early June and early July. Increased wind mixing led to an increase in the proportion of dinoflagellates. The obtained results emphasized the need to consider the patchy nature of the environment and the leading role of protected shallow waters when assessing coastal productivity.
Diatoms are the most common unicellular algae in the seas. One of the reasons for their widespread distribution is considered to be high allelopathic activity. This review focuses on intra- and inter-group diatom allelopathy. We discuss different approaches to studying microalgae’s allelopathic activity in vitro and explore the mechanisms of allelopathic effects among diatoms, as well as the properties of substances associated with allelopathic activity. Such substances are polyunsaturated aldehydes, which are present in all Bacillariophyta, domoic acid, found in representatives of the genera Pseudonitzschia, Nitzschia and Amphora, and marennine produced by Haslea ostrearia and H. karadagensis.
Porpita porpita (Linnaeus, 1758), a colonial hydrozoan belonging to the family Porpitidae, has been recorded for the first time from the Cochin estuary, southwest coast of India. Detailed morphological and molecular analyses have been carried out to confirm species identity. Multiple molecular markers, including mitochondrial COI, nuclear 18S rRNA, and the ITS region, have been used for DNA barcoding, and the sequences have been deposited in EMBL/GenBank (under accession numbers MT576016, MT569147, and MT569977). Phylogenetic analyses based on COI and 18S rRNA have confirmed the placement of P. porpita within Porpitidae, clustering with Velella sp., while ITS has shown closer affinity to Zanclea sp. This record from the Cochin estuary extends the known geographical distribution of P. porpita and provides complementary molecular data, including ITS sequences, contributing to a broader understanding of the species’ diversity and ecological range.
This study presents an analysis of the application of the general-purpose convolutional neural network model Detectron2 (COCO-Detection/faster_rcnn_R_50_FPN_3x) for the automatic detection of macroscopic organisms in underwater video footage obtained in the Chukchi Sea using remotely operated vehicles (ROVs). The relevance of this work stems from the urgent need to develop methods for non-invasive biodiversity monitoring in Arctic seas and the lack of annotated underwater fauna datasets for training classification and detection models. In representative video fragments from different bottom types (silty-sandy, silty-sandy-shelly, and rocky), the model with the detection probability threshold disabled processed every third frame. After minor additional processing, the detection results of the neural network were compared with those of similar work performed by a human. It was shown that on silty-sandy and silty-sandy-shelly sediments, the results of the neural network were comparable to those of a human: high metrics of accuracy (0.8), recall (0.8), and the harmonic mean or F1-score (0.80–0.82) were achieved, with the detection results of the model and a human matching for 50
The photoreceptors and visual pigments of several coastal cottoid fish species (Cottoidea) from the Sea of Japan have been studied by microspectrophotometry and chromatography (HPLC). In the silverspotted sculpin Blepsias cirrhosus (Pallas, 1814) and the tentacled sculpin Porocottus allisi (Jordan Starks, 1904), cones have increased long-wavelength sensitivity, with spectral sensitivity maxima up to 600–625 nm. Such a property is provided by a porphyropsin/rhodopsin mixture in photoreceptors and is combined with the yellow-orange corneal filters having changeable coloration. Some species exhibit individual differences in the composition of the visual pigment mixture. An assumption is made that the properties of the visual pigments and the light-protective eye media in sculpins and closely related species are an adaptation to shallow-water habitats (including the littoral zone) with bright light conditions during daytime.
Sivash Bay is the world’s largest hypersaline lagoon, which has undergone several changes in recent history due to anthropogenic impact. The Southern Sivash is rapidly transforming ( 40 psu salinity rise for 3 years) from a brackish lagoon into an ultra-hypersaline body of water. The purpose of this research was to analyze changes in the state of individual biotic and abiotic components of the Southern Sivash ecosystem under conditions of shifting salinity. The components studied included the bacteriobenthos community (heterotrophic, thionic, and sulfate-reducing bacteria), meio- and macrozoobenthos, and phytoplankton. Additionally, the salinity of the lagoon, the hydrogen index (pH), and the redox potential (Eh) of bottom sediments were analyzed. The study showed that the number of taxa in the meiobenthos community remained unchanged, but the number of organisms decreased almost 12-fold. No correlation was found between the spatial variability of salinity and pH under the studied conditions, while the relationship between Eh and salinity showed a negative trend. From a spatial perspective, it was possible to identify relationships between the state of various biotic components—such as specific bacterial groups (sulfate-reducing and thionic bacteria) and microalgae groups—and the distribution of physicochemical environmental indicators. It can be concluded that no significant changes have been observed in the microbiota of bottom sediments at the level of bacterial groups, despite the temporal transformation of environmental factors. However, the salinity levels have reached critical thresholds for many aquatic organisms, as indicated by the collapse of the macrozoobenthos community, the marked decline in meiobenthos, and the reduced abundance and diversity of microalgae.
Four morphological parameters (body length, cephalothorax length, abdominal length, and furcal setae number) were analyzed in adult specimens of the parthenogenetic population of a brine shrimp Artemia parthenogenetica, a polymorphic species collected from the waters of the Kara-Bogaz-Gol Bay, Caspian Sea. Significant intrapopulation variability in furcal setae number and insignificant variability in body length, abdominal length, and cephalothorax length were observed. A strong negative correlation was found between salinity and furcal setae number. For the first time, salinity has been shown to influence the cephalothorax length in specimens of parthenogenetic population. It is suggested that this may be related to the hydrochemical composition of the bay’s waters.
Seaweed surfaces harbor diverse epiphytic bacteria that are crucial for the health and development of their hosts. The present study explored the diversity and enzymatic production by the culturable epiphytic bacteria associated with green (Ulva lactuca and Halimeda opuntia), red (Amphiroa anceps), and brown (Sargassum wightii) seaweeds collected from the Mandapam coastal region, the southeast coast of India. Twenty-five bacterial isolates were identified by sequencing of the 16S rRNA gene and were found to belong to two common phyla, Firmicutes (17 isolates) and Proteobacteria (8 isolates, class Gammaproteobacteria), and four different families (Bacillaceae, Moraxellaceae, Pseudomonadaceae, and Halomonadaceae). In addition, the isolated bacteria were screened for the production of six enzymes such as agarase (EC 3.2.1.81), amylase (EC 3.2.1.1), cellulase (EC 3.2.1.4), gelatinase (EC 3.4.24.62), esterase (EC 3.1.1.1), and proteinase (EC 3.4.21). Twenty (80
Two artificial microbial consortia (AMCs) were created using the marine heterotrophic bacterial culture collection at the National Scientific Center of Marine Biology, Far Eastern Branch, Russian Academy of Sciences. The use of AMCs as a test system for analyzing the antimicrobial activity of bacteria and their extracts, microscopic fungi, nanoparticles, and other components of antifouling coatings was compared with a natural seawater consortium (NSC). The consortia included representatives of the most common bacterial classes in the marine environment that were easily culturable and did not exhibit antagonism toward other consortium members. It was found that the activity of the test objects toward individual consortium member strains was lower or absent altogether compared with the activity toward the entire consortium.The activity of each test object toward the AMCs was stable, clear, and reproducible, in contrast to the results with the NSC.
This study considers changes in the taxonomic, biogeographic, and trophic composition of polychaete worms in Kola Bay (Barents Sea) during periods of climatic variations and anthropogenic stress. Based on data collected within the periods 1934–1935 and 2021–2025, we have assessed the dynamics of quantitative characteristics of polychaete populations at 10 monitoring stations. Values of the key metrics such as taxonomic richness, abundance, biomass, and productivity have increased in the recent period. These trends are likely influenced by a combination of factors including warming, human activities, and differences in sampling methods between the 1930s and the recent benthic surveys. The findings suggest a high degree of adaptability among polychaetes in response to changing environmental conditions, as well as ongoing borealization trends within the bay’s marine ecosystem.
The article elucidates the species composition of chitons of the genus Placiphorella distributed in boreal waters of the northwestern Pacific Ocean, including a new species, P. kurilensis sp. nov. This species inhabits only waters near the Kuril Islands at depths from 40 to 100 m. It has a uniform walnut coloration of tegmentum, sparse arrangement of bristles near the valves, and a ratio of the antemucronal area length to the length of the tail valve postmucronal area of 3.1–3.4.
To assess the genetic variation of coho salmon (Oncorhynchus kisutch (Walbaum, 1792)) from rivers of northeastern Russia, polymorphism of nucleotide sequences of the NADH dehydrogenase subunit 2 and cytochrome b oxidase mtDNA genes with a total length of 2112 bp was analyzed. In nine samples over different years, 16 haplotypes at 17 polymorphic sites were identified in 133 coho salmon specimens. The purifying selection in the studied genes was detected with a high probability by the Neutrality tests and the Bayesian approximation method. The median network showed the existence of two haplogroups separated by five mutation steps. According to the chronogram inferred from Bayesian dating analysis, the initial stage of divergence of haplogroups began about 182 ka ago. Within the haplogroups, several periods of haplotype divergence were identified within time intervals of 54.3–40.4, 16–12, and 8–7 ka ago. Bayesian skyline data showed an increase in median effective population sizes (NeT) within 10–8 ka ago. The history of haplotype divergence in coho salmon populations reflects paleoclimatic oscillations in the region.
Studies were conducted in the intertidal zone of Vostok Bay in 2021–2023 at the same sampling stations as in 1990. Thirty-seven macrobenthos communities were identified, but only half of them were common to both 1990 and the 2020s. In the 2020s, communities that were not recorded in 1990 developed. In the upper intertidal subzone, the Gloiopeltis furcata community was found on hard sediments, the Ruditapes philippinarum community was typical for mixed sediments dominated by sand, and the Assiminea possietica community was associated with the silty-sandy intertidal zone. In the middle intertidal subzone, the rocky-bouldery sediment was occupied by the communities of Dictyota dichotoma, Laurencia nipponica, Symphyocladia marchantioides, etc.; the sandy-pebbly-bouldery sediment was occupied by the Gracilaria vermiculophylla and Campylaephora kondoi communities; and the silty-sandy sediment was occupied by the Batillaria cumingii community. In the lower intertidal subzone, the Sargassum pallidum and S. miyabei communities were found for the first time. The middle intertidal Hapterophycus primoriensis community was recorded in 2021, but it was absent in 2022 and 2023. The Silvetia babingtonii community of the middle intertidal subzone and the Saccharina angustata and Coccophora langsdorfii communities of the lower intertidal subzone were typical for Vostok Bay in 1990, but they were not found in the 2020s. A biomass similarity of the communities between 1990 and the 2020s exceeding 40
Lecithotrophic larvae of Pilidiophora represent a modified pilidium without its hat-like appearance and reduced larval lobes and lappets but sharing its pattern of juvenile development from imaginal discs and juvenile rudiments. Until the 1960s, only three types of lecithotrophic larvae of Pilidiophora were described: incapsulate Desor’s larva, Schmidt’s larva, and swimming Iwata’s larva. To date, about 18 forms of swimming lecithotrophic larvae have been identified, of which only pilidium nielseni has been studied by confocal laser scanning microscopy (CLSM). Here, using CLSM with phalloidin labeling, we have described the juvenile development of the swimming lecithotrophic larva of the heteronemertean Nipponomicrura sp. In the gastrula stage, six juvenile rudiments synchronously appear; in 2-day-old larvae, two more rudiments (cerebral organ discs) are formed. All eight juvenile rudiments are derived from the ectoderm and, in 5-day-old larvae, they gradually fuse together to form the complete juvenile body. Larvae of Nipponomicrura sp. are more similar to the Iwata’s larva: almost all rudiments appear at about the same time in the embryo in the gastrula stage, while the cerebral organ discs are formed in free-swimming larvae. Issues concerning the development of the cerebral organ and proboscis apparatus in nemerteans are discussed. A unique feature of lecithotrophic larvae of Pilidiophora is that the rudiments of the cerebral organs are initially associated with the foregut. We assume that the proboscis epithelium in Pilidiophora and Hoplonemertea has an ectodermal origin, regardless of the way it forms.
The article presents data on nemerteans from Vietnam recorded over the past 10 years since the publication of Nemerteans of the Coastal Waters of Vietnam, as well as new findings and descriptions of two new species, Notospermus gena sp. nov. (Pilidiophora, Lineidae) and Tetrastemma potapovi sp. nov. (Hoplonemertea, Tetrastemmatidae). To date, a total of about 100 nemertean species are known from the coastal waters of Vietnam. Distributions of some of them are discussed.
