Studying sanitary and hygienic conditions of bream and water in its habitat

The article highlights the data on microbiological monitoring of fish raw materials and water of the Volga-Caspian fishing channel in 2020-2021. The most indicative organisms for assessing the quality of the aquatic environment are benthos-eating fish. Bream Abramis brama (Linnaeus, 1758) is one of the valuable objects of fishing in the Astrakhan region. As a commercial object of river coastal fishing, bream has a higher bacterial contamination than fish caught in the sea. In this regard, studying the conditions for bacteriocenosis of fish raw materials, as well as the factors that determine the pathogenicity of its microflora and sanitary and epizootic monitoring by the microbiological tests remain the most relevant research of aquatic organisms. Quantitative and qualitative indicators of the bream microflora were estimated, according to the analysis of 180 species. The indicators of the water microflora were analyzed using the results of studies of 90 samples. The species identification of the isolated microflora was carried out according to the Bergey identification keys. In the samples of bream muscles there was determined the total number of facultative anaerobic microorganisms and aerobic mesophylls, presence of coliform microorganisms, as well as a causative agent of Staphylococcus aureus, pathogenic bacteria Salmonella and Listeria, and parahemolytic vibrios Vibrio. The study results were processed, according to the methods of biological statistics in the Microsoft Excel 2010 software. The results are presented as mean values and standard errors (M ± m). The general microbiological analysis of the fish muscle tissue confirmed the satisfactory sanitary state of bream Abramis brama (L., 1758) caught in the fishing area of the Volga-Caspian Canal during the study period. Pathogenic microflora in the form of E. coli bacteria, bacteria Salmonella, L. monocytogenes and St. aureus were not found

Molecular Structure and Hybridization Patterns of Abramis brama × Rutilus rutilus Hybrids from Modrac Reservoir, Bosnia and Herzegovina

Interspecific hybridization in the Cyprinidae family has been recorded worldwide, with Abramis brama (bream) and Rutilus rutilus (roach) as one of the often-reported hybridizing pairs. The only account of such an event in Bosnia and Herzegovina has been in Modrac Reservoir. Using morphological and molecular markers, the presence of hybrids was surveyed, the hybridization direction was determined and the hybrid group structure in this ecosystem was evaluated. Our findings confirmed unhindered natural hybridization between roach and bream in Modrac Reservoir. Over 50% of the hybrid specimens were classified as F2 hybrids by the NewHybrids software, while the rest were categorized as pure parental form, making it the first such finding in Europe. The analysis of mitochondrial cytochrome b showed that 90% of hybrid individuals were of bream maternal origin. The hybrid group expressed higher mean values of observed heterozygosity and gene diversity than both parental species. Signs of introgressive hybridization between parental species were detected. The hybrid zone of Modrac Reservoir appears to follow the intermediate or “flat” hybrid model based on the balanced distribution of parental and hybrid genotypes. Further investigation is needed to elucidate the factors that enable the survival and mating success of post-F1 individuals.

Fatty acid composition and lipid quality indices of bream Abramis brama (Linnaeus, 1758) of Lake Kotokel (Western Transbaikalia)

This paper describes the study of fatty acid (FA) composition and lipid quality indices of bream Abramis brama (Linnaeus, 1758) from Lake Kotokel (Western Transbaikalia). In the muscle tissues of bream sampled in 2009 and 2019, high levels of polyunsaturated fatty acids (PUFA), including essential docosahexaenoic (DHA), eicosapentaenoic (EPA), and arachidonic acids were measured. Indicators of nutritional quality based on the fatty acid composition showed that the values of the hypocholesterolemic/hypercholesterolemic (HH) ratio indices were sufficiently high. The atherogenicity (AI) and thrombogenicity (TI) indices, which are indicators for the nutritional value, were less than 1 in the studied fish. In terms of flesh-lipid quality (FLQ), bream had the highest proportion of total EPA + DHA. According to the obtained data for the composition of fatty acids in the muscle tissue of the studied fish from Lake Kotokel, the anthropogenic load on Lake Kotokel has not yet had a statistically significant effect on the fish muscle quality.

Cyanobacteria, cyanotoxins, and their histopathological effects on fish tissues in Fehérvárcsurgó reservoir, Hungary

Cyanobacteria are important members of lake plankton, but they have the ability to form blooms and produce cyanotoxins and thus cause a number of adverse effects. Freshwater ecosystems around the world have been investigated for the distribution of cyanobacteria and their toxins and the effects they have on the ecosystems. Similar research was performed on the Fehérvárcsurgó reservoir in Hungary during 2018. Cyanobacteria were present and blooming, and the highest abundance was recorded in July (2,822,000 cells/mL). The species present were Aphanizomenon flos-aquae, Microcystis flos-aquae, Microcystis wesenbergii, Cuspidothrix issatschenkoi, Dolichospermum flos-aquae, and Snowella litoralis. In July and September, the microcystin encoding gene mcyE and the saxitoxin encoding gene sxtG were amplified in the biomass samples. While a low concentration of microcystin-RR was found in one water sample from July, analyses of Abramis brama and Carassius gibelio caught from the reservoir did not show the presence of the investigated microcystins in the fish tissue. However, several histopathological changes, predominantly in gills and kidneys, were observed in the fish, and the damage was more severe during May and especially July, which coincides with the increase in cyanobacterial biomass during the summer months. Cyanobacteria may thus have adverse effects in this ecosystem.

УСЛОВНО-ПАТОГЕННАЯ БАКТЕРИОФЛОРА ЛЕЩА (ABRAMIS BRAMA L.) ВИСЛИНСКОГО ЗАЛИВА

Проведено исследование микрофлоры леща (Abramis brama L.) Вислинского залива с видимыми патологиями на кожных покровах. Микробиологический анализ пораженных участков кожи и измененных внутренних органов выявил наличие большого количества штаммов условно-патогенных Аeromonas allosaccharophila и санитарно-значимых Сitrobacter freundii бактерий. У леща также отмечено носительство патогенных бактерий Aeromonas hydrophila, обнаруженных в составе микрофлоры кожи. Идентифицированные микроорганизмы при существовании в ассоциациях друг с другом и наличии отрицательно действующих факторов среды способны инициировать инфекционный процесс у леща Вислинского залива

МИКРОФЛОРА ЛЕЩА ABRAMIS BRAMA (LINNAEUS, 1758) ОЗЕРА ВИШТЫНЕЦКОГО В ЛЕТНИЙ ПЕРИОД 2020 Г.

С целью изучения микрофлоры леща оз. Виштынецкого, исследованием которого ранее никто не занимался, произведен микробиологический анализ его кожи, жабр и внутренних органов. Обнаружено доминирование в бактериоценозе леща оз. Виштынецкого бактерий рода Bacillus. Результаты наших исследований были сравнены с данными по микрофлоре леща Куршского залива, полученными сотрудником АтлантНИРО Н. Н. Чукаловой – выявлены различия в видовом и количественном составе бактерий изучаемых водоемов и количестве представителей условно-патогенной микрофлоры.