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The aim of this study, conducted in accordance with both European Union and national legislation, was to evaluate the physicochemical conditions of the Rega River in northern Poland, where efforts are underway to restore its watershed for migratory fish. From 2018 to 2022, water temperature, dissolved oxygen (DO), pH, total suspended solids (TSS), conductivity, alkalinity, total hardness (TH), biochemical oxygen demand (BOD5), chemical oxygen demand (CODCr), nitrite nitrogen (NO2-N), ammonium nitrogen (NH4-N), and total phosphorus (TP) were measured at nine monitoring sites. The results showed that TSS and nitrite nitrogen (NO2-N) were the main factors threatening the suitability of the Rega River as a habitat for salmonid fishes. Additionally, maximum water temperatures occasionally exceeded the tolerance limits for these fishes. Seasonal variations in nitrogen and phosphorus forms, and the dependency of nitrogen forms on DO, indicated disruptions in natural biochemical processes due to surface runoff pollutants from the watershed. This includes fertilizer runoff from agricultural fields and municipal pollution from the towns through which the river flows. The findings underscore the need for continuous monitoring of Rega River waters to safeguard the habitat conditions required by environmentally sensitive fish species. [ABSTRACT FROM AUTHOR]

Highlights: What are the main findings? The high specific surface area of the biofilter media has a positive effect on nitrification. The smooth surface of the biofilter medium reduces the efficiency of nitrification. What is the implication of the main finding? Passive biofilter activation can be used in salmonid RAS. P and C concentrations do not limit nitrogen transformation processes. High-performance biofilters for water purification in recirculating aquaculture systems (RAS) ensure the safety of cultures of highly nutritious fish. As the most critical step in the functioning of biofilters is their activation, the objective of this study was to evaluate the suitability of commercial artificial media, namely RK Plast (BR-1), Mutag-BioChip30 (BR-2), and LevaPor (BR-3), for the passive activation of biofilters used in rainbow trout farming. Changes in NH4+-N, NO2−-N, NO3− -N, phosphorus, and carbon concentrations were analyzed. In the first period, an increase in NH4+-N concentration was recorded, before an increase in NO2−-N concentration (maximum concentrations ranged 0.728–1.290 and 0.982–5.198 mg N dm−3, respectively), followed by a reduction and stabilization to a level safe for the fish (both below 0.100 mg N dm−3). Concurrently, a steady increase in NO3−-N concentration was noted, with a maximum concentration between 6.521 and 7.326 mg N dm−3. Total phosphorus and total carbon ranged from 0.423 to 0.548 mg P dm−3, and from 43.8 to 45.2 mg C dm−3. The study confirmed the feasibility of using the tested artificial biofilter media for rainbow trout farming in RAS with passive biofilter activation. Biofilter activation efficiency was highest for the media with the highest specific surface area (BR-2 and BR-3). The removal of ammonium nitrogen and nitrite nitrogen was above 90%. Nitrogen biotransformation was not limited by phosphorus or carbon concentrations. [ABSTRACT FROM AUTHOR]

Although interest in the use of membranes for the concentration of microalgal biomass has steadily been growing, little is known regarding the phenomena of membrane fouling. In addition, more attention has been given to polymeric membranes compared to ceramic membranes, which have a longer life that is associated with a higher resistance to aggressive chemical cleaning. In this study, microfiltration (MF) and ultrafiltration (UF) of two microalgae species, Chlorella vulgaris and Monoraphidium contortum, were carried out using tubular crossflow ceramic membranes. Permeate flux was measured, resistance was calculated, and dissolved organic carbon (DOC) was determined. The flux reduction during the first 10 min of filtration was higher for MF than UF (>70% and <50%), and steady-state permeate fluxes were <5% (for MF) and <25% (for UF) of initial (in m3 m−2 s−1) 6.2 × 10−4 (for MF) and 1.7 × 10−4 (for UF). Total resistances (in m−1) were in the ranges of 4.2–5.4 × 1012 (UF) and 2.6–3.1 × 1012 (MF) for M. contortum and C. vulgaris, respectively. DOC reduction was higher for UF membrane (>80%) than for MF (<66%) and DOC concentrations (mg C L−1) in permeates following MF and UF were about five and two, respectively. In conclusion, we demonstrated: (i) higher irreversible resistance for UF and reversible resistance for MF; (ii) permeate flux higher for UF and for M. contortum; (iii) the significant role of dissolved organic compounds in the formation of reversible resistance for MF and irreversible resistance for UF. [ABSTRACT FROM AUTHOR]

Chinese mitten crab (Eriocheir sinensis) is a valued foodstuff in China. However, their elemental composition is still poorly understood. Therefore, the aim of this study was to quantify the concentrations of Al, As, Ca, Cd, Cu, Fe, K, Mg, Na, Ni, Pb, Se, and Zn in muscle, hepatopancreas, gonads, gills, and exoskeletons of E. sinensis caught in spring and autumn in the Szczecin Lagoon, and to compare these levels to Dietary Reference Intake. High levels of Ca (>20, 000 μg g−1) in the exoskeleton, K (5,980 μg g−1) and Zn (80.8 μg g−1) in muscle, Ni (0.678 μg g−1) and Cd (0.3278 μg g−1) in the hepatopancreas, As (0.0411 μg g−1) and Se (0.3208 μg g−1) in the gonads, Fe (204 μg g−1), Cu (59.0 mg g−1), and Pb (0.0742 mg g−1) in the gills were measured. The edible parts of E. sinensis caught in Poland can be a valuable source of macro- and microelements important in human diet. Levels of Pb and Cd did not exceed the established food safety level of 0.50 μg g−1. The results showed that introduction of commercial fishing of this species may be profitable and would also comply with the European Union's legal regulations concerning the reduction of invasive animal populations in Europe. • Eriocheir sinensis is an invasive species in Polish waters. • E. sinensis can be a valuable source of elements important in human diet. • Edible parts of crabs from Szczecin Lagoon can be considered toxicologically safe. • Commercial fishing of E. sinensis may be profitable. [ABSTRACT FROM AUTHOR]

Following the culturing of post‐juvenile African catfish, wastewaters were purified using single and integrated processes. Iron coagulant (IC), aluminium coagulant (AC), lanthanum modified bentonite (LMB) and ceramic membranes (NF – nanofiltration) were each tested in single processes, while the combination of IC + NF and AC + NF were used in the integrated process tests. Among the single processes, membrane filtration was the most effective in purifying the aquaculture effluent. The total suspended solids (TSS) were removed entirely and there was a near‐complete removal of turbidity (99.2%), as well as effective removal of Al and Fe (80.8% and 67.4% respectively). Precipitating agents overall removed TSS most faithfully, from 37.5% removal with AC, through 50.2% with IC, to 62.3% with LMB. Using integrated processes, the highest removal efficacy was recorded for TSS (100%) and turbidity (99.7% – IC + NF; 99.9% – AC + NF). Additionally, integrated processes attained a 96.8%–98.4% removal of NO2‐‐N. This study confirms the possibility of using IC, AC and LMB in chemical purification of effluents from recirculating aquaculture systems (RAS). However, due to their low removal efficacy for nitrogen and phosphorus, it is preferable to use NF or integrated processes – membrane filtration combined with chemical precipitation, methods which proved to be most effective for water purification in RAS. [ABSTRACT FROM AUTHOR]

The Chinese mitten crab ( Eriocheir sinensis ) is an invasive species in the Baltic Sea catchment area. Its numbers in fishery are steadily growing and can potentially become a considerable export product. However, the meat of these crustaceans is known to accumulate contaminants, such as trace elements. Therefore, in this study we examined the content of Al, As, Cd, Co, Cr, Cu, Fe, Mn, Mo, Ni, Pb, U, Zn in the claws, legs, and carapace of Chinese mitten crabs from Lake Dąbie (south-western catchment area of the Baltic Sea). Concentrations of Mo and U were within the sensitivity limit of the analytical method, and the average concentrations (in mg kg −1 dw) of the remaining elements ranged from 0.016 (Cd, claw meat) to 191 (Fe, carapace). The meat had very high concentrations of essential metals (Fe > 20, Cu > 17, Zn > 16, Mn > 2, in mg kg −1 dw). The concentrations of Pb and Cd were 5 and 100 times lower than the threshold for foods established by the Commission Regulation (EC) No 1881/2006. The meat of crabs from Lake Dąbie should be safe for consumers and may be a source of elements playing important functions in metabolic processes. [ABSTRACT FROM AUTHOR]

The present study was carried out to investigate the possibility of using ceramic membranes for microalgal biomass densification and to evaluate the qualitative composition of the permeate as a source of nitrogen and phosphorus for microalgae cultivated in a closed system. The studies were conducted on the microalga Monoraphidium contortum . The microfiltration process was carried out on a quarter-technical scale using ceramic membranes with 1.4 μm, 300 and 150 kDa cut-offs. Permeate flux and respective hydraulic resistances were calculated. Dissolved inorganic nitrogen and phosphorus fractions were measured in the feed and the permeate. It was noted that the permeate flux in the MF process was decreasing while the values of reversible and irreversible resistances were increasing as the cut-off of the studied membranes was diminishing. An analysis of the hydraulic series resistance showed that using a 300 kDa membrane would be the most beneficial, as it was characterized by a comparatively high permeate flux ( Jv = 1.68 10 − 2 m 3 /m 2 s), a comparatively low susceptibility to irreversible fouling (1.72 · 10 9 1/m) and a high biomass retention coefficient (91%). The obtained permeate was characterized by high concentrations of dissolved nitrogen and phosphorus forms, which indicated that it could be reused in the process of microalgal biomass production. [ABSTRACT FROM AUTHOR]

One of the alternative wastewater treatment methods aimed at the elimination of heavy metals is membrane separation supported by the use of metal-complexing polymers. Many sectors of industry generate wastewater containing both heavy metals and protein substances which show complex-forming properties. In this study, a 450 Da molecular weight cut-off nanofiltration ceramic membrane (TAMI Industries, France) was tested to evaluate the retention of Zn, Cd, Pb, Cu and Fe complexed with bovine serum albumin (BSA). Retention levels were tested in water solutions solely for the metals and for the metals with the addition of BSA, depending on the pH of the solutions (from 2.0 to 9.0). It was noted that the retention tended to increase as the pH increased. For solutions composed with only metals, retentions exceeding 80% were noted for pH > 6.9. The addition of a complexing agent resulted in high retentions of Cu, Cd and Zn already at pH = 2.0. Maximum retentions for Zn, Cd, Pb, Cu and Fe were noted for solutions containing the mixture of metals and BSA at pH = 6.0 (97, 96, 90, 95 and 71%, respectively) and at pH = 9.0 (93, 99, 93, 99 and 85%, respectively). The studies confirmed the high metal-complexing capacity of BSA and indicated that heavy metals might be effectively removed from wastewater containing protein in the process of membrane separation using a ceramic membrane. [ABSTRACT FROM AUTHOR]

Nitrogen and phosphorus release during decomposition of Notothenia coriiceps (Richardson, 1844) fillets kept in seawater was examined in the laboratory. Amounts of N-NO, N-NO, N-NH, total inorganic nitrogen, total organic nitrogen (TON), total nitrogen (TN), total reactive phosphorus, total organic phosphorus (TOP), and total phosphorus (TP) released during a 5-day exposure were measured. The highest average release (from the standard 100 g fillet wet weight) was typical of TON and TN (2.574 and 2.703 mgN dm, respectively) as well as of TOP and TP (1.526 and 2.648 mgP dm, respectively). The release was observed to be most intense during the initial 120 min of decomposition. As shown by the accumulation rate coefficient, the highest rate of nutrient accumulation in water was typical of organic forms of N and P (0.827 and 1.329, respectively). Organic nitrogen and organic phosphorus accounted for 94 and 54 % of TN and TP release, respectively. In the experiment, nitrogen and phosphorus were released from the fish remains with leached chemicals, which may form important chemical cues for scavengers. [ABSTRACT FROM AUTHOR]

Our paper presents a study on the middle reaches of the Ina River. Select physical and chemical indicators were analyzed in order to evaluate water quality. It was determined that the studied river was subjected to strong anthropopressure, and factors declassifying river water included CODCr, TP, general hardness, and alcalinity. A high level of biogenic elements was additionally increased by pollution discharged to the river in the proximity of a factory specializing in agricultural production and processing food and agricultural produce near the town of Stargard Szczecinski. The process of self-purification was noted, which can be considered as a factor modifying changes and dynamics of nitrogen and phosphorus in the studied river, leading to an internal enrichment with biogenic elements. Those processes were multi-directional as confirmed by PCA analysis, where component 1 accounted for just 36.7% of the total variance, and the total variance exceeding 90.0% was only noted for 7 components. [ABSTRACT FROM AUTHOR]

Fish roe is among important components of human diet, but its elemental composition is rather poorly known. In this study we used inductively coupled plasma mass spectrophotometer (ICP-MS) to examine the content of As, Cd, Co, Cr, Mn, Mo, Ni, Pb and Se in the roe of sturgeon, sea trout and rainbow trout. In addition, risk assessment for consumer health was conducted by the determination of estimated daily intake (EDI), target hazard quotient (THQ), hazard index (HI) and carcinogenic risk (CR). Overall, the elements formed the following sequence (mean values in μg kg−1): Se (1173) > Mn (785) > Ni (58.9) > As (27.6) > Mo (14.5) > Co (2.25) > Cr (1.31) > Pb (0.96) > Cd (0.41). The greatest concentrations of As, Co, Cr, Ni and Pb were recorded for the sturgeon roe, and the greatest Cd and Mo concentrations for the sea trout roe. The EDI values did not exceed permissible oral reference doses, the THQ were much below the permissible levels (THQ < 1), and the CR were at least within the permissible range (CR < 10−4). In conclusion, bioaccumulation of elements depended on the fish species, and for Cd, Co, Cr and Pb it was smaller than that observed in the roe of fish from other regions of the Earth. No risk for consumer health in terms of CR, THQ and HI values was detected in the examined roe. Assuming a small index of roe consumption, it can be concluded that its consumption should not pose a threat to human health. • Sturgeon roe had the highest content of As, Co, Cr, Ni, Pb. • The elements in the roe formed the sequence: Se>Mn>Ni>As>Mo>Co>Cr>Pb>Cd. • EDI of all the elements was below oral reference dose (RfD). • Consumption of Se contained in 10 g roe was ca. 3% RfD. • No-carcinogenic (THQ<1) or carcinogenic (CR<10–4) risks were found. [ABSTRACT FROM AUTHOR]

Macro-ionic composition of fish opercula may be an indicator of the fish stock identity. This is especially interesting in river estuaries, where individual sections of the estuary may differ in terms of their hydrochemical regimes. Diversified macro-ionic tissue composition is likely to provide clues not only about the origin of an individual fish, but also about its possible migration routes. The current study researched this aspect of the chemical composition of perch collected from different sections of the Oder River estuary. A total of 60 European perch, Perca fluviatilis L., were obtained from 3 sampling sites located in the river at Widuchowa, Szczecin Lagoon, and Pomeranian Bay, where waters are subject to dynamic macro-ionic transformations. Fish length ranged from 20 to 25 cm. Opercula of the fish were examined for their content of calcium, magnesium, strontium, sodium, and potassium, with the aid of the flame method using a Perkin-Elmer 3100 atomic absorption spectrophotometer. Perch inhabiting the waters of the Oder River between Widuchowa and Szczecin Lagoon had their opercula composed predominantly of calcium. Calcium was also the predominant ion dissolved in the water in this area; Ca represented 83.6% of all cations in the water and 41.6% of those present in the bones of the perch operculum. The increased levels of salinity near the sea were associated with the replacement of calcium in bones by other, more readily available elements (magnesium or strontium). Differences in the observed macro-ion composition of the opercula were sufficient to assign the perch studied to two distinct groups inhabiting fresh and brackish waters. [ABSTRACT FROM AUTHOR]

The Oder River creates one of the largest estuaries in Poland. The estuary can be divided into three zones, each with a different hydrochemical regime: the Pomeranian Bay (salt water habitat), the Szczecin Lagoon (brackish water habitat), the Oder River up to the Widuchowa section (transitional environment - brackish and typical freshwater). The Pomeranian Bay was characterized by the lowest concentration of nutrients throughout the research series in comparison to the other regions. It had a low nitrogen to phosphorus proportion and the highest stability of variability in total nitrogen concentration. The Szczecin Lagoon was characterized by a higher concentration of nutrient loads in comparison to the Pomeranian Bay, by a lower nitrogen and phosphorus proportion than the Oder waters, and by the high stability of variability of concentrations of mineral nitrogen and total nitrogen. As the "nutrient trap" for the Oder estuarine system, the Oder River, with its highest nutrient concentration, is characterized by the highest stability of variability of total nitrogen concentration. [ABSTRACT FROM AUTHOR]

The aim of the present paper is to present the results of a study on the impact intensive carp (Cyprinus carpio L.), feeding with extruded commercial feed has on the quality of cooling waters. The feed studied had varied fat and carbohydrate contents. The study also revealed the optimal hydrochemical conditions of cooling waters for carp fanning. Cage farming caused growing loads of organic matter, nitrogen, and phosphorus in the water. Experimental extraction of feed from the water revealed that high fat fish feed was more stable in comparison to high carbohydrate fish feed. Intensive carp fanning with these two feeds led to considerable fish weight gain in both feed groups, but the weight gain for the carp fed with high fat feed, in comparison with that of carp fed with high carbohydrate fish feed, was significantly greater (p<0.01). [ABSTRACT FROM AUTHOR]

• Male Chinese mitten crab males had a higher condition factor than the females. • Concentrations of Ca, Fe, Cu, Mn, Al, Cd, Co, and Ni were highest in the hepatopancreas. • Crab muscle had the lowest Pb and Mo concentrations and the highest Se, K, Zn, and Cr. • The consumption of crabs from the Elbe River should be safe for the health of the consumer. The Chinese mitten crab (Eriocheir sinensis) is an invasive species in Europe. This study aimed to determine the levels of Al, As, Ca, Cd, Co, Cr, Cu, Fe, K, Mg, Mn, Mo, Na, Ni, Pb, Se, and Zn in the muscles and hepatopancreas of female and male and in the gonads of females caught in the Elbe River (Germany), relative to water and sediment levels, using an atomic absorption spectrometer. Elemental levels were compared with the Dietary Reference Intakes (DRI). The results showed that females had significantly higher muscle levels of Cr and Zn than the males, and males had significantly higher hepatopancreas levels of Cd, Se, and Co. Generally, the hepatopancreas had significantly higher levels of most elements than the gonads and muscles. Levels of Cu, Fe, and Zn exceeded the Recommended Dietary Allowances. The levels of all the elements were below the Tolerable Upper Intake Level, and Tolerable Daily Intakes for Pb, Cd, Cr, Co, and As were not exceeded. In conclusion, the edible parts of the crabs can be an excellent supplement to the human diet, and the intake of 100 g portions a day will not exceed DRI for the studied elements. [ABSTRACT FROM AUTHOR]

The separation efficiencies of aqueous solutions containing nitric salts of Zn, Cu, Fe or Pb at various pH in process of nanofiltration have been investigated experimentally. These results were used to obtain the total volume membrane charge densities, through mathematical modelling based on the Donnan–Steric partitioning Model. The experimentally obtained retention values of individual heavy metal ions varied between 36% (Zn2+ at pH = 2), 57% (Pb2+ at pH = 2), 80% (Fe3+ at pH = 9), and up to 97% (Cu2+ at pH = 9). The mathematical modelling allowed for fitting the total volume membrane charge density (Xd), which yielded values ranging from −451.90 to +900.16 mol/m3 for different non-symmetric ions. This study presents the application of nanofiltration (NF) modelling, including a consideration of each ion present in the NF system—even those originating from solutions used to adjust the pH values of the feed. [ABSTRACT FROM AUTHOR]

Analysis of the physicochemical properties of fresh eggs (raw material for caviar production) of the Salmonidae [sea trout (Salmo trutta L. 1758) and rainbow trout (Oncorhynchus mykiss, Walbaum 1792)] and the acipenseridae [siberian sturgeon (Acipenser baeri Brandt, 1869)], as well as sturgeon hybrids (Acipenser baeri Brandt, 1869 × Acipenser gueldenstaedti Brandt & Ratzeburg, 1833), included determination of basic physicochemical parameters (pH, dry weight, content of protein, fat, fiber and ash), amino acid composition and fatty acid profile. Compared to the Acipenseridae, Salmonidae eggs yielded a 22.5% higher total protein content, a 40.0% higher level of essential amino acids (EAA) and a 57.5% lower crude fat content. The sea trout eggs showed also a completely different fatty acids profile and hence values of lipid indices (lowest PUFA value – 11.72%, highest SFA value – 39.86%). The rainbow trout and sturgeon eggs had a similar fatty acid profile, and were characterized by a high nutritional and dietary value. [ABSTRACT FROM AUTHOR]

The aim of the study was to investigate the effect of iron coagulant (IC), aluminum coagulant (AC) and lanthanum modified bentonite (LMB) on the embryogenesis of pike. Physicochemical indicators of the water were determined according to the methods recommended by APHA (1999). The applied precipitating agents (IC, AC, LMB) at appropriate concentrations were sprayed on the surface of water in aquariums with the pike eggs placed on nets. The eggs were observed under a microscope, documenting their development using digital photography NIS Elements Br software. The number of fertilized eggs, embryo survival, and the percentage of malformed larvae were determined. The pike eggs and hatched larvae were recorded and measured. The percentage of fertilized eggs was found to be the highest in the control sample (LW) and in the IC sample (94% and 93.3%, respectively), 85.9% in the AC sample and 81.8% in the LMB sample. The pace of pike embryogenesis in the samples was identical – the embryos in both the control and other samples reached individual stages of embryonic development with an equal number of degree days (DD). The IC group hatched the earliest, and the control sample was the last to hatch (LW). In the control sample, the hatched larvae were the longest and had the lowest percentage of malformed individuals. The control sample also had the highest rate of embryo survival (85.9%), while the lowest was in the LMB sample (68.6%). These results indicate that the application of precipitating measures to improve water quality should not coincide with the periods of fish reproduction. • The percentage of fertilized pikes eggs was found to be the highest in the control sample without precipitating agents. • The influence of selected coagulants on pike embryogenesis indicate a negative correlation between the use of water restoration agents and the development of fish. • The application of precipitating measures should not coincide with the periods of fish reproduction. [ABSTRACT FROM AUTHOR]

Quantitative and qualitative transformations of nitrogen compounds in the Integrated Multi-Trophic Aquaculture (IMTA) system using the Media Filled Beds (MFB) method in plant cultivation was investigated experimentally. Three fish tanks were populated with 200 individuals of common carp (Cyprinus carpio L.) in each. The experiment lasted over three months. The following parameters were determined on the weekly basis: ammonium nitrogen, nitrate (III) nitrogen, nitrate (V) nitrogen, total nitrogen, mineral nitrogen, organic nitrogen and dissolved oxygen, according to commonly adopted methods. Water samples for the analyses were taken directly from the fish tanks and locations directly after each type of filtration (mechanical, biological and hydroponic). The presence of all determined forms of nitrogen was established including the mineral nitrogen which concentration remained at levels sufficient for a normal growth and development of plants. Active nitrification process was detected. Loss of nitrogen from the system was not only due to absorption by plants. Initiation of the anaerobic ammonia oxidation (anammox) and denitrification processes was observed. • Presented investigations enhance the knowledge and understanding of quantitative nitrogen transformations in aquaponic. • Presented investigations enhance the knowledge and understanding of qualitative nitrogen transformations in aquaponic. • Presented investigations illustrate influence of Media Filled Beds in plant cultivation on nitrogen cycle in the system. [ABSTRACT FROM AUTHOR]

Simple Summary: Freshwater crayfish species are critical for both local communities and the modern food industry. The study characterised the meat of invasive spiny-cheek crayfish, analysing the yield, basic chemical composition, nutritional value, as well as culinary value. Crayfish meat has high nutritional parameters due to favourable fatty acid and amino acid profiles, as well as balanced mineral content. Crayfish meat is an alternative to livestock meat in the human diet and draws attention of the food industry to the processing of underutilised resources of high-quality aquatic species. The aim of the study was to present a comprehensive characterisation of crayfish meat, which is crucial to assess its potential usefulness in the food industry. To this end, we assessed the yield, basic chemical composition (protein, fat, minerals), nutritional value (amino acid and fatty acid profiles, essential amino acid index (EAAI), chemical score of essential amino acids (CS), hypocholesterolaemic/hypercholesterolaemic ratio (h/H), atherogenicity (AI) and thrombogenicity (TI) indices), as well as culinary value (lab colour, texture, sensory characteristics, structure) of the meat of spiny-cheek crayfish (Faxonius limosus) (n = 226) from Lake Sominko (Poland) harvested in May–September 2017. Crayfish meat, especially that from the abdomen, was shown to have high nutritional parameters. It is lean (0.26% of fat), with a favourable fatty acid profile and a very high quality of fat (PUFA (sum of polyunsaturated fatty acids):SFA (sum of saturated fatty acids), n-6/n-3, h/H, AI, TI) and protein (high CS and EAAI). It is also a better source of Ca, K, Mg, Na, P, and Cu than meat from slaughter animals. Hence, crayfish meat can be an alternative to livestock meat in the human diet. Owing to its culinary value (delicateness, weak game flavour, and odour), it meets the requirements of the most demanding consumers, i.e., children and older people. [ABSTRACT FROM AUTHOR]

• Heavy metal accumulation was sex-, season- and body part-dependent. • The content of heavy metals in F. limosus tissues is safe for human consumption. • 100 g of abdomen meat covers 42 % (P) and 14 % (Zn) of the daily requirement. Spiny-cheek crayfish (Faxonius limosus , Rafinesque, 1817) females and males were examined as an alternative source of highly valuable material currently sought by the food industry. The aim of the study was to assess the profiles of 14 macro- and microelements (Al, Ca, Cd, Cu, Fe, K, Mg, Na, Ni, P, Pb, Se, Si, Zn) in the meat, exoskeleton and eggs (females) of crayfish collected in the spring and autumn seasons in the Lake Sominko (Poland). The content of heavy metals was analysed, and the degree of their accumulation in crayfish tissues was determined. The profile of the investigated elements in the tested samples was variable depending on the body part, sex of individuals and season of sample collection. A portion of crayfish abdomen meat or eggs (100 g) is particularly rich in P (41.5–73.9 %) of daily requirement), Zn (14.1–38.5 %), Mg (7.9–21.5 %), K (3.3–13.1 %) and Na (4.6–7.7 %) and small quantities of Ca (0.8–2.5 %) and Al (0.9–4.7 %). The study confirmed that consumption of crayfish meat is toxicologically safe and nutritionally complete. [ABSTRACT FROM AUTHOR]