The extract of the White Sea sponge Halichondria panicea (Pallas, 1766) exhibits cytotoxic and cytostatic effects. The main part of the extract consists of hydrophilic low molecular weight compounds: free amino acids (13.9%), glucose (19.9%), polyatomic alcohols (glycerin and others) (6.1%), carboxylic acids (0.7%) and nitrogenous heterocycles (1.2%). Of the substances specific to the metabolome, bicyclic diketopiperazines (four derivatives), pyroglutamic acid, phenylacetic acid, and two steroids (3β,5α)cholest-7-en-3-ol and dihydrocholesterol were identified. Toxicants characteristic of the genus Halichondria were not found in the White Sea sponge.

This paper presents the results of a study of the macroalgal flora in Unskaya Inlet (White Sea) that was carried out in 2022–2023. The checklist of macrophytes, summarized from original and literature data, comprises 94 species: Chlorophyta, 26; Rhodophyta, 34; Phaeophyceae, 30; Xanthophyceae, 2; Charophyceae, 1; and Cyanophyta, 1. Of these, 46 species are new to the region, 4 are new to the White Sea, and 2 are new to the flora of Russia. From the offshore part to the head of Unskaya Inlet, the coastal surface runoff leads to significant freshening and increased turbidity of water, thus causing a sharp depletion of the species composition of algae.

The report provides new data on Vaucheria vipera Blum, one of the rarest collected marine species. In 2023, V. vipera was discovered in the littoral zone of the Unskaya Inlet of the White Sea. The record is considered first in Russia and the Arctic Ocean. The study of the morphology of specimens from the White Sea allowed to expand the morphological range of the species in terms of the maximum dimensions of oogonia, oospores, and antheridia. The work also pays attention to the basal septa that separate short branches bearing the gametangia. Based on the morphology of the gametangia, it is proposed to transfer this species to the section Woroninia.

The pumping rate of the White Sea sponge Halichondria panicea (Pallas, 1766) (Porifera: Demospongiae) was estimated under laboratory conditions. We used live specimens with a wet weight of 3.5 to 35.5 g and one to eight oscula. The pumping rate of a sponge was determined as the sum of pumping rates of all its oscula, which was calculated as the product of the maximum velocity of the excurrent flow from an osculum by the cross-sectional area of that osculum. The velocity was measured using a microthermistor sensor. The pumping rate of the sponge was found to be related to its weight by a power relationship with an exponent of approximately 3. Sponges weighing 25 g and over surpass in pumping activity solitary animals such as the bivalves Mytilus edulis and Hiatella arctica and the ascidian Styela rustica , in which the relationship is either a linear or power one, with an exponent less than one. The advantage of the sponge over solitary organisms seems to be due to its modular organization, which ensures not only a constant increase in the number and size of oscula as the individual grows, but probably also leads to a periodic restructuring of the irrigation system.

An ecosystem engineer’s influence on associated organisms includes 2 components: physical and biological. The physical component is the spatial environment created by the ecosystem engineer, while the biological component is the physiological activity of the engineering species. However, little is known about the ratio between these components. We evaluated this ratio for Mytilus edulis L. by means of a field experiment in which communities of organisms that developed on bare ceramic plates (controls, C) were compared with those that formed on plates carrying patches of live mussels (L) or artificial patches made of mussel dummies (D). The experiment was performed using 2 different age-size groups of mussels and dummies (small-young and large-old). Live mussels had only a weak positive effect on species richness of the associated organisms, but the structure of the communities that formed on tests plates (L, D and C) differed significantly. The similarity of the communities of associated organisms between C and L was 1.5-3 times less than between C and D. Mussel size-age factor had no significant effect on community structure other than on the algal assemblage. The results of this experiment suggest that the influence of mussels on associated organisms cannot be reduced to only the effect of increasing complexity of the spatial environment. The influence of the biological component is significant and can exceed that of the physical component. Thus, in ecosystem engineering, non-living spatial structures cannot serve as an identical substitute for a population of living organisms.

Paint coatings based on a copolymer of vinyl chloride with vinyl acetate with an additive of epoxy-diane resin of six different compositions are developed. The coatings differ in the nature of fillers (anatase, rutile, and cobalt and lanthanum oxides) and the composition of soft biocidal additives of the atrane class (protatrane of salicylic acid and hydrometallatranes based on triethanolamine complexes with zinc(II) and copper(II) salts). The process of biofouling in the natural conditions of the White sea is studied. Fouling communities formed on the studied plates during 2.5 months of exposure to the sea is analyzed, depending on the composition of the coatings. The fouling is based on the attached forms: scyphistomas (polypoid stage) of jellyfish Aurelia aurita and Cyanea sp., mussels Mytilus edulis, and hydroid Obelia longissima. The efficiency of the same paint coating appear to differ towards different species of fouling organisms.

Currently, there is little comparative data on 'efficiency' of different engineering species, i.e. species richness, density and biomass of the associated organisms that have been supported by engineering species. The use of fouling communities makes it possible to compare the efficiency of different engineering species under the same conditions, which is necessary to obtain correct estimates and difficult to do when studying natural bottom communities. In this study, we have analysed the fouling communities in four different mussel culture farms in the White Sea to test the following hypotheses. (1) Different engineering species (mussel Mytilus edulis, solitary ascidian Styela rustica, sponge Halichondria panicea) have different assemblages of the associated vagile fauna. (2) Mytilus edulis is the most efficient engineering species, i.e. species richness, species diversity, density and biomass of the associated vagile fauna is higher in the mussel communities than in those dominated by Styela rustica or Halichondria panicea. The first hypothesis was confirmed, while the second was rejected. In all the culture farms studied, all parameters of the mussel-associated vagile fauna were not higher and in most cases were even lower than those of the fauna associated with ascidians or sponges. The reason for this seems to be the very dense packing of mussels in patches. Therefore, Mytilus edulis is not the most efficient engineering species among fouling organisms, at least in the conditions of the subarctic White Sea. The data obtained are particularly important in view of the ever-increasing volume of anthropogenic substrate and fouling communities in coastal marine ecosystems.

Assessment of the acute toxicity, safety and biological activity of lipophilic extracts of the White Sea brown algae“– S. latissima and F. vesiculosus– on the model of zoohydrobionts Daphnia magna Straus has been performed.Two methods of obtaining dry lipid concentrate of kelp and fucus were tested. It has been shown that the acute toxicity of the lipid extract of kelp does not depend on the method of its preparation and is about 200 mg/L. The acute toxicity of fucus extract depends on the method of preparation. It is about 100 mg/L in the «cold» method of extraction and increases by an order of magnitude in the «hot» method. To study the biological activity, samples of brown algae obtained by «cold» extraction were used.In chronic experiments, preparations of brown algae were used in a concentration of 8.0 mg/L, which was less than 0,1 LC50 of the acute toxicity of fucus and did not cause toxic effects.For 24 days, the preparations were introduced in contact with Daphnia twice a week. Subsequently, the control and experimental hydrobionts were kept under the same conditions until the death of the last individuals. It has been shown that the preparations of S. latissima and F. vesiculosus in the proposed concentration by 20-30% increased the lifespan of Daphnia in normal conditions and by 50-60% in extreme conditions, while stimulating the reproductive activity of aquatic organisms by 3-4 times. The results obtained suggest that the studied drugs have pronounced adaptogenic and cytoprotective effects.

Mussel beds are common in many intertidal and subtidal habitats, including sub-Arctic and Arctic regions. Despite their ecological importance, little is known about the demographic processes governing the development of mussel beds and particularly about the synchronization of these processes at different spatial scales. The development of a relatively compact, narrow littoral mussel bed of Mytilus trossulus, extending several hundred m along the shore of Koni Peninsula (Tauyskaya Bay, northern Sea of Okhotsk), was studied for four years during the period 2014–2017. This model bed was located along an exposed coast with a seasonal sea ice cover. It was used to test the hypothesis that small-scale synchronization exists, i.e., the changes in demographic structure of the population that occur simultaneously within a single mussel bed follow a similar pattern. This hypothesis was rejected. The size structure of the mussel population at the same tidal level changed from being uniform (2014) to being varied in 2015–2017. The course of development of the mussel population was different at the opposite ends of the bed. The cause of these differences may be unequal levels of recruitment of juveniles in the form of a gradient from one end of the bed to the other over the length of the bed. The gradient was associated with transition from one type of shore dynamic processes to another (accumulation vs. abrasion). Small-scale desynchronization may represent one of the reasons explaining the heterogeneity of mussel populations. The possibility of desynchronization of demographic processes should be taken into consideration when studying the spatial organization and dynamics of mussel beds.

The influence of the F-55 water-soluble fraction of brown algae extract Fucus vesiculosus on the development of organotypic tissue culture of various origins from three germ layers in young and old rats was studied. The F-55 preparation has a stimulating effect on the processes of cell proliferation in tissues of ecto-, ento- and mesodermal genesis (cerebral cortex, myocardium, spleen, and liver) by regulating the processes of cell proliferation and apoptosis. The revealed strengthening of regeneration processes in explants from both young and old rats under the influence of the F-55 preparation in ultra-low concentrations of 10–100 ng/mL can be used to produce new, medicinal, cytoprotective substances that allow the enhancement of cell regeneration in various tissues under pathological conditions, including those associated with age.

Halichondria panicea, commonly known as the breadcrumb sponge, is an ecologically aggressive and widespread species in the coastal waters of North Atlantic and North Pacific. Cytostatic activity of the water-soluble extract fraction from the White Sea sponge Halichondria panicea was tested using organotypic cultures of rat liver fragments. The study shows a pronounced negative dose-dependent effect of the extract on the development of tissue explants of the test animals. Our results confirm toxicity of the White Sea Halichondria panicea, which was revealed earlier toward marine epibenthic organisms. The chemical nature of a substance or substances responsible for toxic effect is discussed.

The formation of early fouling communities developing under different spatial orientations of substrates and various lighting conditions was studied during a field experiment. The algal predominance on the sunlit upward-oriented sides and the animal predominance on the shaded downward-oriented sides are the consequence of two processes: (1) competitive displacement of animals from the sunlit sides by algae; (2) preferential colonization of the shaded downward-oriented sides of the substrates by animals.

During laboratory testing it was shown that the presence of the White Sea sponge Halichondria panicea on the shell of the mussel Mytilus edulis negatively affects the functional state of the mollusk as expressed in the increased heart rate recovery time after functional test loads (a 50% water salinity drop for 1 hour). It was found that the degree of this negative influence rises with an increase both in the projective cover of mussel shells by the sponge and in the size/age parameters of mussels.

In epibenthic communities algae are usually predominant on sunlit substrates, while animals dominate shaded surfaces. Two possible factors that cause this are a higher competitive ability of algae and the evolutionarily defined differentiation of niches that results in animals avoiding competition with algae. We attempted to shed light on this duality by initally making the following assumption: if the key determinant for algal dominance on sunlit surfaces is niche differentiation rather than competitive exclusion, then a community already formed by animals must be impervious to algal expansion under any light conditions. This hypothesis was tested in a field experiment that used the early fouling communities developing in the upper water layer in the White Sea, Russia. Fouling communities were allowed to develop on the top sides and bottom sides of horizontal plates. After a period of exposure in water, the plates were inverted. It was shown that if the substrate orientation is reversed, the fouling community is transformed into the community that conforms to the new lighting conditions. An increased light intensity resulted in the degradation of the zoocenosis and changed its structure, whereas shading did not lead to degradation and change in the algocenosis, but caused stunting of algal growth. Our results indicate that algocenoses are more stable and have more competitive ability than zoocenoses in early fouling communities. The animal predominance on the shaded surfaces is likely to be a consequence of both competitive displacement of animals from the sunlit surfaces by algae and preferential colonization of the bottom surfaces by animals.

The ability of the sponge Halichondria panicea to assimilate into the fouling communities of the blue mussel Mytilus edulis and the solitary ascidian Styela rustica has been studied in a field experiment, in which sponge fragments have been introduced artificially into epibenthic communities. The growth of H. panicea was suppressed greatly in the presence of young mussels; its survival rate averaged 40%. In the communities where S. rustica dominated, the survival rate of H. panicea reached 100%, but the growth rate was lower than in the control group (without competitor species). Despite the high natural growth rate and toxicity, the settlement success of H. panicea was low on the substrate occupied by another fouling species.

Laboratory experiments showed that the mussel Mytilus edulis aggregated more intensely around living organisms (the bivalve Hiatella arctica and the solitary ascidian Styela rustica, which commonly co-occur with mussels in fouling communities) than around inanimate objects. When exposed to an inanimate object, mussels attached their byssal threads primarily to the substrate, close to the object, but when exposed to a living organism, they attached their byssal threads directly to the organism. The ascidian was more intensely covered with byssal threads than was the bivalve. Mussel attachment to the ascidians was apparently determined by the physical characteristics of the tunic and to a lesser extent by the excretion-secretion products released by S.rustica. This study indicates that mussels can use byssus threads as a means of entrapment of potential competitors for space. It remains unclear why mussels preferentially attached to ascidians compared to the bivalve. This can be explained either by competitive interactions, or by attractiveness of the ascidian tunic as an attachment substratum.

Spatial and temporal features of algal colonization at mussel culture farms in the Kandalaksha Bay of the White Sea were studied in summer (2013). 37 species of macroalgae have been found including 17 species in the young mussel community and 33 - in the mature community. The algae (including diatoms and blue-green algae) play a significant role in the early stages of development of fouling community; their biomass reaches 17-18 %. Subsequently, the role of diatoms and cyanobacteria in the community is reduced, and the composition of macroalgae is enriched by both larger forms and small or microscopic epiphytes of hydroids and macrophytes. In the long-term fouling algae biomass could be 5-6 %. The greatest diversity of algae is observed on the mussels and among them; growth of the algae on an artificial substrate under mussels is depressed. It has been established that at culture of mussel and kelp in the White Sea a composition of algae of fouling communities is similar and is related to benthic associations Saccharina latissima.