This work provides data on sex ratio, body sizes and body weight, weight growth of individuals of the Harris crab (Rhithropanopeus harrisii). Using of an original method of morphometry, created for the species R. harrisii, made it possible to compile a biometric passport database for the species from the Taman Bay. The evaluation of biology features showed dominance of males in the sample (3.4 times, there were no juveniles), which may be a consequence of the specifics of material collection or indicate instability of habitat conditions, including insufficient food availability; the carapace length of individuals was 6.2–15.1 mm, carapace width – 7.7–26.3 mm. Ma- ximum and average sizes of females were smaller by 1.3 and 1.7 times, respectively. The peculiarities of sexual dimorphism of the species were described for the first time in terms of the size of exoskeleton parts (carapax, abdomen, claws of clawed and merus walking legs); the sizes of most plastic characters in males exceeded those of females by 9–45% (exception - width of the fourth segment of abdomen - it was larger in females by 28%). New features of the morphology of the species have been obtained: the right chela of both sexes’ individuals is 7–16% larger than the left one. The individual body weight of crabs in general is 0.17–3.83 g, with males being larger than females by an average of 63%. Size-weight relationship has been evaluated: weight growth of both males and females is slightly ahead of their linear growth.  The paper presents recommendations on measurements of crab abdominal segments when estimating abdomen width.

The data on the species composition, occurrence, and distribution of summer zooplankton in the south-eastern part of the Baltic Sea for 2018 and 2022 have been analyzed. During the research period, the zooplankton was represented by 29 species and taxa of higher order: Rotifera – 5, Copepoda – 11, Diplostraca – 9, Scyphozoa – 2, Ctenophora – 1, Appendicularia – 1. Among the meroplankton, larvae of Polychaeta, Bivalvia, Gastropoda, Cirripedia, and fish eggs have been noted. The community's biomass was mainly composed of planktonic crustaceans, predominantly calanids. Inter-annual differences in the overall biomass of zooplankton indicators have been identified: the value range in 2018 varied within 324-3217 mg/m³, and in 2022 – 911600 mg/m³. Despite this, the spatial distribution of biomass in both years showed significant similarity. Using interpolation tools in ArcMap software environment ArcGIS, maps of continuous biomass distribution of zooplankton have been constructed based on total catches (2018 and 2022) and by layers (2022): surface layer (up to depths of 30 m), intermediate layer (from 30 to 50 m), and deep layer (from 50 m to the bottom). Biomass concentrations were noted in the coastal zone down to the depths of 50 m near the end of the northern coast of the Sambian Peninsula and along the Curonian Spit, as well as closer to the slope of the Gotland Basin in both years. The analysis of the distribution of total zooplankton biomass in water layers revealed different accumulation areas, and these differences are largely due to the composition of dominant species and thermohaline conditions in each specific layer.

Currently, one of the most promising and most high-tech ways of farming is aquaponics. It is a combination of two technologies: aquaculture (breeding and cultivation of aquatic organisms) and hydroponics (growing plants without soil). The necessity and urgency of developing and applying of different variants of such technology is justified by the need of aquaculture enterprises to increase profitability of production. Aquaculture is an industry associated with high production and economic risks. Availability of additional products, such as vegetable crops, will allow enterprises to gain additional income and provide greater stability in the market. The aim of this work was to create an experimental aquaponic plant and to investigate the peculiarities of the system functioning. The article presents data on the results of experimental cultivation of Australian red-clawed crayfish and microgreens of Radish mix (varieties China Rose + Red Coral) in aquaponic system based on recirculatory aquaculture system (RAS) for 8 days, as well as green peas Madras for 12 days. The paper also contains a schematic diagram of the RAS installation and considers productivity of this system in terms of plants, as well as an assessment of biochemical processes of water purification from organic contaminants. The studies have shown that cultivation of Australian red-clawed crayfish (Cherax quadricarinatus (Von Martens, 1868)) in this aquaponic system is quite effective, and the cultivation of radish and pea microgreens is comparable to classical hydroponics in terms of yields: similar indicators of plant development and yields have been obtained at the same normative terms of cultivation. 

The study is related to the possibility of using native collagen-containing additive obtained from pike-perch (Sander lucioperca) scales to replace more expensive gelatin of animal origin in the formulation of milk jelly. A pilot batch of collagen-containing additive from fish scales has been produced and its total chemical composition has been determined: moisture – 7.2%, protein – 71.4%, fat – 1.4%, ash – 20.0%, including calcium (Ca) – 6.5%, phosphorus (P) – 3.8%. According to the presented recipe of milk jelly its control sample (with animal gelatin) of the following general chemical composition has been obtained: moisture – 82,35%, protein – 4,10%, fat – 2,75%, carbohydrates – 9,9%, total ash – 0,9%, as well as the experimental sample (with fish collagen-containing additive and gelatin) respectively: moisture – 82,77%, protein – 4,74%, fat – 2,49%, carbohydrates – 8,9%, total ash – 1,1%. It has been shown (by calculation method) that the experimental sample of milk jelly has a reduced energy value (76.97 kcal) compared to the control (80.75 kcal). It has been found that fish collagen-containing additive in the formulation of milk jelly contributes to the increase in the yield of finished products, compared with the control. Organoleptic characteristics of experimental and control samples of milk jelly have been studied. It has been found that the experimental sample of milk jelly (in structure resembling soft ice cream) differs from the control by more dense and elastic consistency and less sweet flavour. Partial replacement of animal gelatin with collagen-containing additive in the formulation of milk jelly, contributes to its enrichment with products of hydrolysis of fish collagen and biogenic calcium, as well as involvement in industrial production of significant amounts of little-used fish scales.

Baltic amber is a symbol of the Kaliningrad region and the whole Russia. The use of non-liquid (fine-dispersed) fractions of amber is currently not included in the technological schemes of the Kaliningrad Amber Plant. This study proposes the application of one of the components of amber waste, namely, succinic acid, which constitutes about 10% of the weight of the waste. Its annual production can reach two tons. Along with the well-known properties of succinic acid as an energy substrate, antioxidant, a substance involved in diabetes prevention, and a contributor to the formation of the body’s radio-resistance; it has also been found to have the potential for transformation into gamma-aminobutyric acid, which belongs to the group of adaptogens and has non-pharmacological effects on the human body. According to current sanitary regulations, succinic acid can be included in beverages. This work presents a scheme and discusses the mechanism of possible transformation of succinic acid into gamma-aminobutyric acid in the Roberts cycle (aminobutyrate shunt). The developed technological scheme for producing a dry product, enriched not only with succinic acid but also with essential trace elements (magnesium, calcium, and potassium), can be used to reduce transportation costs, while the beverage itself can be bottled directly into consumer containers in the form of aqueous solutions obtained from the dry substance. It is assumed that this sparkling drink will also become an attribute of celebrations and will be used to create a festive atmosphere. This research is relevant against the backdrop of growing interest in a healthy lifestyle and the need to reduce the negative consequences associated with alcoholism, drug dependence, and the use of neuroleptics to improve the overall health of the body.

Production of soft cheeses is a promising and relevant direction, since their technology is distinguished by the efficient use of raw materials and short maturation periods. Finished products are characterized by an increased content of calcium, vitamins A, B₂, B₁₂, PP and can be recommended for the prevention of diseases of the musculoskeletal system. It is known that vitamin C and calcium have a key influence on the processes of collagen bio-synthesis and bone metabolism. Combination of these components when paired with complete proteins and fats contributes to the best absorption of all nutrients. Therefore, enrichment of soft cheeses with low-molecular-weight collagen peptides and vitamin C makes it possible to create a complex product with an osteotropic orientation from it.  The article presents a formulation of soft cheese of increased biological value for the prevention of diseases of the musculoskeletal system. The state of health of the population of the Russian Federation is characterized, which indicates the prevalence of osteoporosis and osteopenia among the inhabitants of the country, as well as an increasing shortage of calcium and vitamin C intake. The introduction has been substantiated of enriching components into the composition of soft cheese – hydrolyzed Baltic cod skin as a source of collagen and sea buckthorn fruits, which are rich in vitamin C. The process of acid hydrolysis of collagen–containing raw materials has been studied using the example of two types of whey - curd and cheese. The parameters of acid hydrolysis of Baltic cod skin in curd serum have been analyzed and determined. Using the method of mathematical planning of the experiment, the formulation of enriched soft cheese has been selected and recommendations for its use have been described. Thus, 70 g of cheese per day satisfies a person's daily need (based on theoretical calculations) for calcium by 39.6%, phosphorus by 51.5%, vitamin A by 24.5% and vitamin B₂ by 15.5%, collagen by 42%.

During exploitation of marine motor oil, the processes related to the oxidative high-temperature degradation, contamination with soot, wear metals, fuel, water and coolant occur. The quality of used marine motor oil is an indicator for diagnosing the malfunction of marine diesel, so the analysis of the properties of used motor oils is important in determining the reliability of marine diesel engines, as well as ensuring the optimal time of their use. Marine motor oils are dielectrics, which allows considering various electrical characteristics in diagnostic tasks. This paper presents the results of a study of the main physical and chemical characteristics of fresh and used motor oils: relative permittivity, dielectric loss tangent, specific conductivity, water percentage, electrical breakdown voltage, total base number, and viscosity. The authors use a multiparameter approach to analyze the properties of fresh and used motor oils. The temperature dependences of the main physical and chemical characteristics of the following motor oils have been studied: Mobil 5W30, Mobil 5W40, Mobil 10W40, Shell Rimula 15W40, Total DISOLA, Navigo TPEO 12/40. The specified characteristics have been measured depending on the temperature in the range of 20–55 ºC (in 1 ºC increments), both for fresh and used oils. The paper shows the possibility of establishing a correlation between these characteristics, including when they change in used motor oils. The presence of a correlation between these parameters allows this to be used in the tasks of diagnosing marine diesel engines.