Intensive Fish Farming Research Articles

Parasite scars: the impact of salmon lice injury on sea trout populations.

Spillback effects of the parasitic salmon louse from fish farms to wild fish are a critical environmental concern for countries with wild salmon. The ectoparasitic louse causes significant physical and physiological damage to wild salmonids that probably have long-term impacts on individuals and population dynamics. However, empirical links between injuries and abundance of lice have not been established in the wild. This study establishes a strong association between dorsal fin injuries in wild sea trout (Salmo trutta) and infestation with salmon lice at a marine site in Norway. We further assessed the prevalence of such injuries on sea trout returning to spawning grounds from snorkelling observations in 16 rivers in Hardangerfjord, western Norway, from 2007 to 2021. The prevalence of injuries decreased with distance from the fjord outlet, from approximately 70% in middle and outer parts to approximately 10% in the inner parts. Additionally, a negative correlation was found between sea trout population size and the proportion of the population with dorsal fin damage. The results demonstrate that salmon lice inflict high levels of injury on significant portions of sea trout populations in areas with intensive fish farming, leading to poorer population status in affected populations.

Quantitative proteomic analysis of plasma membranes from the fish pathogen Saprolegnia parasitica reveals promising targets for disease control.

The phylum Oomycota contains economically important pathogens of animals and plants, including Saprolegnia parasitica, the causal agent of the fish disease saprolegniasis. Due to intense fish farming and banning of the most effective control measures, saprolegniasis has re-emerged as a major challenge for the aquaculture industry. Oomycete cells are surrounded by a polysaccharide-rich cell wall matrix that, in addition to being essential for cell growth, also functions as a protective "armor." Consequently, the enzymes responsible for cell wall synthesis provide potential targets for disease control. Oomycete cell wall biosynthetic enzymes are predicted to be plasma membrane proteins. To identify these proteins, we applied a quantitative (iTRAQ) mass spectrometry-based proteomics approach to the plasma membrane of the hyphal cells of S. parasitica, providing the first complete plasma membrane proteome of an oomycete species. Of significance is the identification of 65 proteins enriched in detergent-resistant microdomains (DRMs). In silico analysis showed that DRM-enriched proteins are mainly involved in molecular transport and β-1,3-glucan synthesis, potentially contributing to pathogenesis. Moreover, biochemical characterization of the glycosyltransferase activity in these microdomains further supported their role in β-1,3-glucan synthesis. Altogether, the knowledge gained in this study provides a basis for developing disease control measures targeting specific plasma membrane proteins in S. parasitica.IMPORTANCEThe significance of this research lies in its potential to combat saprolegniasis, a detrimental fish disease, which has resurged due to intensive fish farming and regulatory restrictions. By targeting enzymes responsible for cell wall synthesis in Saprolegnia parasitica, this study uncovers potential avenues for disease control. Particularly noteworthy is the identification of several proteins enriched in membrane microdomains, offering insights into molecular mechanisms potentially involved in pathogenesis. Understanding the role of these proteins provides a foundation for developing targeted disease control measures. Overall, this research holds promise for safeguarding the aquaculture industry against the challenges posed by saprolegniasis.

Water-in-oil adjuvant challenges in fish vaccination: An experimental inactivated adjuvanted vaccine against betanodavirus infection in Senegalese sole.

The extensive growth of intensive fish farming has led to a massive spread of infectious diseases. Nervous necrosis virus (NNV) is the causative agent of the viral encephalo- and retinopathy disease which has become a major threat for fish farming all over the globe. The devastating mortality rates recorded in disease outbreaks, especially when infected specimens are at early stages of development, have a high economic impact on the sector. Currently, vaccines are the most cost-effective preventing tool in the fight against viruses. Inactivated vaccines have the advantage of simplicity in their development at the same time as present the antigen in a similar manner than the natural infection in the host. Nevertheless, they usually trigger weaker immune responses needing adjuvants to boost their effectiveness. In this work, we have intraperitoneally vaccinated Senegalese sole juveniles (Solea senegalensis) with a previously designed inactivated vaccine against NNV based on binary ethylenimine (BEI), mixed or not with an oil-adjuvant. Our results demonstrated the potential activation of different immune pathways when the vaccine was administered alone compared to the oil-adjuvanted vaccine, both resulting in an equivalent partial improvement in survival following a NNV challenge. However, whilst the vaccine alone led to a significant increase in specific antibodies, in the adjuvanted version those antibodies were kept basal although with a slight improvement in their neutralization capacity. At transcriptional level, neither vaccine (adjuvanted or not) triggered the immune system activation during the vaccination period. However, after NNV infection, the BEI-inactivated vaccines alone and oil-adjuvanted both elicited the stimulation of antiviral responsive genes (rtp3, herc4), antigen presentation molecules (mhcii) and T-cell markers (cd8a) in the head-kidney. Additionally, the oil-adjuvanted vaccine appears to stimulate mediator cytokines (il6) and B-cell markers (ight and ighm). Surprisingly, when the adjuvant was administered alone, fish showed the highest survival rates concomitantly with a lack of NNV-IgM production, pointing to the possible induction of different immune pathways than the B-cell responses via antibodies by the adjuvant. Since this combined vaccine did not succeed in the full extension of protection against the pathogen, further studies should be performed focusing on unravelling the molecular mechanisms through which adjuvants trigger the immune response, both independently and when added to a vaccine antigen.

Preliminary investigation on the occurrence and health risk assessment of antibiotics in cultured tilapia retailed at a commercial outlet in Tema, Ghana

In Ghana, Nile tilapia is one of the most commonly cultivated fish species. Bacterial infections, which mostly occur in intensive fish farming, are considered to be the most significant health issue facing these culture systems in Ghana's aquaculture industry. To prevent, and treat bacterial infections and promote fish growth, antimicrobials are often used, and in most cases at unregulated doses. However, this misuse and neglect of withdrawal durations for such antimicrobials may result in drug residues showing up in fish edible tissue, posing a risk to human consumers. To evaluate the risk to consumers, this study screened for antibiotic residues in popular tilapia fish sold at a retail outlet in Tema. Using ultra-high-performance liquid chromatography-tandem mass spectrometry (UHPLC/MS/MS), the study analysed the levels of 12 antibiotics present in 24 tilapia samples sold at a retail outlet in Tema. Erythromycin, tetracycline, oxytetracycline, and amoxicillin were detected at varying levels, with frequencies of 20.8 %, 62.5 %, 58.3 %, and 54.2 %, respectively. The highest concentration of 3.521 ± 0.32 μg/kg was found for oxytetracycline, while erythromycin had the lowest concentration (0.276 ± 0.11 μg/kg) in the samples. According to the study, the levels of antibiotics detected in the sampled tilapia were lower than the maximum residue limits (MRL) recommended by the WHO. Additionally, both the hazard quotient (HQ) and hazard index (HI) values were less than one. Therefore, consuming retail farmed tilapia purchased from the commercial outlet in Tema metropolis was deemed to pose no significant risk to human health. However, regular monitoring of antibiotics and other contaminants is necessary to minimise their potential impacts on human health.

Fish Responses to Alternative Feeding Ingredients under Abiotic Chronic Stress.

Aquaculture has become one of the most attractive food production activities as it provides high-quality protein for the growing human population. However, the abiotic chronic stress of fish in intensive fish farming leads to a detrimental condition that affects their health and somatic growth, comprising productive performance. This work aims to comprehensively review the impact of alternative and novel dietary protein sources on fish somatic growth, metabolism, and antioxidative capacity under environmental/abiotic stressors. The documental research indicates that ingredients from rendered animal by-products, insects, bacteria as single-cell proteins, and fungal organisms (e.g., yeast, filamentous fungus, and mushrooms) benefit fish health and performance. A set of responses allows fish growth, health, and survival to remain unaffected by feeding with alternative ingredients during chronic environmental stress. Those ingredients stimulate the production of enzymes such as catalase, glutathione peroxidase, and selenoproteins that counteract ROS effects. In addition, the humoral immune system promotes immunoglobulin production (IgM) and cortisol plasmatic reduction. Further investigation must be carried out to establish the specific effect by species. Additionally, the mixture and the pre-treatment of ingredients such as hydrolysates, solid fermentations, and metabolite extraction potentialize the beneficial effects of diets in chronically stressed fish.

Impacts of cyanobacterial metabolites on fish: Socioeconomic and environmental considerations

AbstractThe increasing global population has led to rising demand for food, particularly protein. As an excellent source of protein, fish play a crucial role in meeting this demand, making aquaculture a highly impactful industry. Floating cages have been developed as a method of fish management and production to achieve high productivity and volume. However, these intensive fish farming practices can contribute to eutrophication, leading to changes in primary producers and promoting the excessive proliferation of cyanobacteria. Cyanobacteria blooms pose significant consequences to aquatic ecosystems, including potential risks to fish exposed to harmful cyanobacterial metabolites. Cyanobacterial metabolites encompass various chemical classes, such as terpenoids, carotenoids, alkaloids, cyanopeptides, amino acids, organophosphates, macrolides, and lipopolysaccharides. Some of these compounds' toxicity and impact on fish farms still need to be better understood. Cyanotoxins and off‐flavour compounds in fish farms can pose risks to water and fish quality and potential health hazards for humans throughout the food chain. Therefore, cyanobacteria in fish farms can have significant economic, environmental, and public health implications. This review examines the concerns associated with cyanobacterial natural products in fish farming, including off‐flavours, known cyanotoxins, and other potentially toxic compounds, while exploring their socioeconomic and environmental risks.

Dihydroartemisinin alleviates ammonia toxicity and autophagy in zebrafish (Danio rerio) gill

Ammonia is highly toxic to aquatic organisms and has become a consistent pollutant in intensive fish farming conditions. Dihydroartemisinin (DhA) has potential value in the treatment of ammonia poisoning in aquaculture. However, the application investigation of DhA is insufficient in the field of aquaculture. In the present study, 540 zebrafish with an average body weight of (1.00 ± 0.01) g were randomly assigned into 9 groups. The zebrafish were fed a basal diet supplemented with or without 0.25% or 0.5% DhA for 1 week. The zebrafish were then exposed to water supplemented with or without 40 or 80 mg/L ammonium acetate (NH4AC) for 4 days. The results showed that dietary supplementation with 0.5% DhA attenuated mortality and ammonia accumulation in zebrafish exposed to 80 mg/L NH4AC. In addition, the alleviative effects of 0.5% DhA were associated with enhanced mRNA levels for ammonia transporter (Rhesus-associated glycoprotein, Rh family C glycoprotein 1, Na+/K+-ATPase, carbonic anhydrase), anti-inflammatory cytokines (transforming growth factor β), as well as the down-regulation of mRNA expression of inflammatory factors (interleukin 1β), hypoxia-inducible factors (hypoxia-inducible factor 1 αb, hypoxia-inducible factor 2α), and protein abundances of autophagy (autophagy-related gene 5, BCL-2-interacting myosin-like coiled-coil protein-1, microtubule-associated protein 1 light chain 3 Ⅱ, cathepsin B, cathepsin L). Taken together, DhA has great potential in aquaculture as a defence against ammonia toxicity.

Inventorying the Broodstocks of Belarusian Carp Breeds and Herbivorus Fish Species by the Genes of the Most Economically Valuable Traits to Maximize the Use of the Physiological Potential of a Fish Organism to Increase Fish Productivity in Ecological Conditions of Intensive Pond Fish Farming

One of the most promising marker genes for assessing and predicting animal meat productivity is the myostatin gene (MSTN). The protein encoded by this gene regulates the development of muscle tissue in various species of terrestrial and aquatic vertebrates. Mutations of the myostatin gene may lead to a twofold and in some cases even a threefold increase in muscle mass in the individuals of different species. Studies are underway to test the breeders of the Belarusian mirror carp and herbivorous fish species for the presence of mutations in the myostiatin gene (MSTN). When revising the broodstock of a new species of the Belarusian mirror carp, the effectiveness of using mutations of the MSTN gene associated with an economically valuable trait of fish productivity and mass accumulation has been established. The fish capacity of the juvenile mirror carp obtained during the reproduction of test breeders, where one parent was a GG homozygote and the other was an AG heterozygote with a mutation by the MSTN gene, was 1.3-1.7 times higher compared to the average productivity in the experimental and control groups and it showed a better productivity indicator for the control groups by 1.1-1.5 times. When testing silver carp and bighead carp selected for study (in Belarus and Uzbekistan), no mutations in the myostatin gene (MSTN) were found.

Morphological and biochemical indicators of the blood of carp fish in artificial water reservoirs

In this article, morphological and biochemical parameters of the blood of carp fish in artificial reservoirs of Samarkand region are analyzed depending on their living conditions and hydro chemical parameters of water. One of the important features of intensive fish farming is the study of blood, morphological and biochemical parameters. The morphological and biochemical composition of blood varies depending on the habitat and lifestyle of different fish species.

Humic Acid Aplication in Catfish Farming Using Bucket System in Muncul Fish Farm, Banyuwangi, Indonesia

In Banyuwangi, Indonesia, where the vast potential of natural resources remains largely untapped optimally, the community partnership program (CPP) was introduced to enhance freshwater fish production, with a specific focus on catfish farming in the Muncul fish farm. The region's catfish production, the largest among consumer fish commodities, had been hampered by traditional and semi-intensive methods, limited facilities, disease risks, and uncertain market conditions. To address these challenges, the CPP employed a participatory approach, fostering a close relationship between the community development team and partner groups. Through scientific problem-solving discussions, valuable input from partners, and active participation in decision-making, catfish farmers were empowered. The central innovation of applying humic acid in a bucket fish farming system significantly improved catfish productivity and profitability. As a result, partners gained knowledge and skills in intensive bucket fish farming, substantially increasing their productivity and income. To further expand the benefits of this program, promoting urban farming concepts, especially the bucket fish farming system, should be encouraged to engage more individuals with limited space in small-scale aquaculture for food security and income generation.

Enhanced chemical recovery of phosphorus from residues of recirculating aquaculture systems (RAS)

In recirculating aquaculture systems, cultivated fish cannot incorporate all the phosphate contained in the feed. Excess phosphate ends up in the culture water and in the sludge produced. If the sludge cannot be valorised directly in agriculture, a chemical recovery as concentrated phosphate is an interesting option to help closing the phosphorus cycle. This study investigates the extent to which accumulated phosphorus can be recovered by acid re-dissolution with subsequent precipitation on sludge from two different recirculating aquaculture systems cultivating African Catfish (Clarias gariepinus). Acid treatment could increase the ratio of dissolved phosphorus available for subsequent precipitation by 53% for extensive and by 61% for intensive fish farming. With the consecutive precipitation in total up to 86% of the phosphorus from the sludge could be recovered. Phosphorus re-dissolution with citric acid requires the highest amount of acid per g dry matter as well as of sodium hydroxide for subsequent precipitation. Sulfuric and nitric acids have comparably lower demands.

Essential oil from Artemisia argyi alleviated liver disease in zebrafish (Danio rerio) via the gut-liver axis.

The popularity of intensive fish farming has led to the emergence of fish diseases characterized by hepatobiliary syndrome. Artemisia argyi (A. argyi) essential oils have anti-inflammatory and anti-oxidant effects. However, their alleviating effects and mechanism on liver disease in fish are still unclear. Thus, adult zebrafish were used to construct an animal model to observe histopathological damages, determine biochemical parameters and expression of inflammatory cytokines and mRNAs in the PPAR-γ/NF-κB pathway, and conduct 16S sequencing of intestinal microbiota. The results found that after treatment with A. argyi essential oil, the histopathological damage caused by ethanol was relieved; the CAT, SOD, and GSH levels were remarkably elevated, while the MDA level was obviously lowered (P<0.05); the expression levels of IL-10 and IFN-γ mRNAs were enhanced, but the levels of IL-1β, IL-6, PPAR-γ, NF-κB, and TNF-α mRNAs were reduced (P<0.05) relative to the EtOH group. A. argyi essential oil remarkably attenuated the damage to intestinal tissue structure, and elevated the levels of Muc2, ZO-1, Claudin-1, and Occludin mRNA (P<0.05). Sequencing of the gut flora showed that A. argyi essential oil significantly altered the composition of gut microbes compared with the EtOH group. In addition, KEGG and COG analyses also showed significant (P<0.05) changes in acetate cycling metabolism in the EtOH group, catechol 2, 3-dioxygenase and nitroreductase were significantly increased (P<0.001), and lipid metabolism and terpenoid synthesis were significantly elevated (P<0.001) in A. argyi essential oil group. The results indicate that A. argyi essential oil could effectively relieve ethanol-caused histopathological damage of livers by modulating the composition of gut microbiota, thus inhibiting the level of IL-1β and mRNAs in the PPAR-γ/NF-κB pathway, increasing the IL-10 level, reducing the oxidative stress. This may offer a rationale for further research on the rationality of A. argyi as a substitute for feed antibiotics in aquaculture.

Feeding-Regime-Dependent Intestinal Response of Rainbow Trout after Administration of a Novel Probiotic Feed

Intensive fish farming is associated with a high level of stress, causing immunosuppression. Immunomodulators of natural origin, such as probiotics or phytoadditives, represent a promising alternative for increasing the immune function of fish. In this study, we tested the autochthonous trout probiotic strain L. plantarum R2 in a newly developed, low-cost application form ensuring the rapid revitalization of bacteria. We tested continuous and cyclic feeding regimes with regard to their effect on the intestinal immune response and microbiota of rainbow trout. We found that during the continuous application of probiotic feed, the immune system adapts to the immunomodulator and there is no substantial stimulation of the intestinal immune response. During the cyclic treatment, after a 3-week break in probiotic feeding and the reintroduction of probiotics, there was a significant stimulation of the gene expression of molecules associated with both cellular and humoral immunity (CD8, TGF-β, IL8, TLR9), without affecting the gene expression for IL1 and TNF-α. We can conclude that, in aquaculture, this probiotic feed can be used with a continuous application, which does not cause excessive immunostimulation, or with a cyclic application, which provides the opportunity to stimulate the immunity of trout, for example, in periods of stress.

The effect of application of effluent water on sage (Salvia officinalis L.) yield and quality in lysimeters

ABSTRACT Cultivation of medicinal plants with the irrigation of agricultural effluents might be of great importance to save fresh water resources, extend cultivation area and increase economic feasibility. We investigated the effects of saline fish farm effluent water, diluted and gypsum-supplemented effluent, and natural freshwater as a control irrigation in lysimeters. Beside plant growth parameters, macronutrient and sodium content and the amount and composition of essential oil of sage plants were measured. Significant differences among irrigation treatments were found in plant height, SPAD value and essential oil content. Seasonal variation was also observed on plant height, nutrient content of the leaves and the total essential oil content. The essential oil components characterised by the highest levels of availability were detected as α-thujone, camphor, ß-thujone, 1,8-cineol and ledol. Under effluent irrigation, the concentrations of - and ß-thujone increased slightly; only camphene, trans-sabinole and caryophyllene-oxide changed significantly. The other main components remained stable. Our analysis of the response of sage to the input of effluent provides a reasonable ground for recommending the utilisation of saline effluent water from intensive fish farming in sage production, thus preventing the wastage of valuable water resources.

A stratified compartmental model for the transmission of Sparicotyle chrysophrii (Platyhelminthes: Monogenea) in gilthead seabream (Sparus aurata) fish farms†.

The rapid development of intensive fish farming has been associated with the spreading of infectious diseases, pathogens and parasites. One such parasite is Sparicotyle chrysophrii (Platyhelminthes: Monogenea), which commonly infects cultured gilthead seabream (Sparus aurata)-a vital species in Mediterranean aquaculture. The parasite attaches to fish gills and can cause epizootics in sea cages with relevant consequences for fish health and associated economic losses for fish farmers. In this study, a novel stratified compartmental epidemiological model of S. chrysophrii transmission was developed and analysed. The model accounts for the temporal progression of the number of juvenile and adult parasites attached to each fish, as well as the abundance of eggs and oncomiracidia. We applied the model to data collected in a seabream farm, where the fish population and the number of adult parasites attached to fish gills were closely monitored in six different cages for 10 months. The model successfully replicated the temporal dynamics of the distribution of the parasite abundance within fish hosts and simulated the effects of environmental factors, such as water temperature, on the transmission dynamics. The findings highlight the potential of modelling tools for farming management, aiding in the prevention and control of S. chrysophrii infections in Mediterranean aquaculture.

Support capacity of a floodplain lake for intensive fish production (Rondônia, Brazil)

The Amazon Basin stands out mainly for its large floodplain’s areas, which during the period of high water become important environments for the maintenance of the life cycle of many fish species. These floodplains act as a source of food and an area for growth and reproduction for the fish assemblages. However, there are few studies on the use of floodplain lakes for breeding fish in confinement. Therefore, we analyzed the support capacity and environmental parameters of Lake Cujubim, in the Madeira River Basin, regarding its use for the implementation of intensive fish farming (net tank system). From 2019 to 2020, bathymetric profiles and limnological data were collected, considering the seasonality of the water level and the shape of the Lake Cujubim. The bathymetry data were primarily used to verify the parameters of depth, area and volume of the lake, while limnological data contributed to statistical analyses for the evaluation of health status and support capacity of the lake for fish farming in an intensive production system. The data collected from the limnological analyses and the depth and profile indicate that Lake Cujubim is suitable for the cultivation of fish, and has an estimated support capacity for an annual production of up to 468.31 tonnes of fish. Herein, we propose a viable alternative for the social and productive development of intensive fish farming in an area of floodplain lake in the state of Rondônia, Brazil.&#x0D; Keywords: Amazon basin, net tanks, pisciculture.

Population genetics and plant growth experiments as prerequisite for conservation measures of the rare European aquatic plant Luronium natans (Alismataceae).

Information provided by population genetic studies is often necessary to effectively protect endangered species. In general, such data is scarce for aquatic plants and this holds also for Luronium natans, an aquatic macrophyte endemic to northwestern and western Europe. It is threatened across its whole distribution range due to human influences, in particular due to eutrophication and intensive fish farming. In spite of habitat protection populations continue to decline and re-introductions are one possibility to prevent the species' extinction. Therefore, insights in genetic diversity and relatedness of source populations is warranted. Thus, we performed Amplified Fragment-Length Polymorphism (AFLP) on two large populations in Saxony, Germany (Großenhainer Pflege and Niederspree), complemented with numerous additional occurrences from Europe. In addition, we conducted experiments on plant growth to assess optimal conditions for ex-situ cultivation taking water temperature, water level and substrate into account. We revealed considerably high levels of genetic diversity within populations (Shannon Indices ranged from 0.367 to 0.416) implying that populations are not restricted to clonal growth only but reproduce also by open-pollinated flowers. Remarkably, the two geographically close Saxon populations were genetically distant to each other but subpopulations within a locality were completely intermingled. Concerning optimal cultivation conditions, longest roots were obtained at temperatures >14°C and saturated, but not submerging water levels. Thus, our findings advocate for a re-introduction scheme from nearby source populations and provide detailed information on successful ex-situ cultivation.

High occurrence of antibiotic resistance genes in intensive aquaculture of hybrid snakehead fish

The increasing abundance of antibiotic resistance genes (ARGs), which are regarded as new pollutants, has raised public health concern. The use of antibiotics in aquaculture has promoted the evolution and spread of ARGs. The occurrence and abundance of ARGs in aquaculture has attracted extensive attention. However, the distribution and transmission of ARGs in aquaculture require further study. This study analyzed water and sediment from intensive culture of hybrid snakehead fish farm in Zhongshan, South China. Twenty-two types of ARGs were detected in all environmental samples. The relative abundance of sulfonamide resistance genes (sul1 and sul2) was the highest, ranging from 3.37×10-2 to 8.53×100 copies/16S rRNA gene. High occurrence of quinolones, phenicols, tetracycline resistance genes, and class 1 integrase gene (intI1) was also observed in pond water samples. This implies that pond water is one of the main reservoirs and origins of ARGs in the aquatic environment. Proteobacteria was the most abundant phylum in all the environmental samples, and its relative abundance ranged from 24.05% to 41.84%. Network and canonical correspondence analyses showed that a high abundance of ARGs (int1, sul1, sul2, qacEΔ1, aac6, and oqxA) was positively correlated with Proteobacteria, Cyanobacteria, and Bacteroidetes, and the abundance of Proteobacteria, Actinobacteria, and Patescibacteria was positively correlated with environmental factors (sulfide, nitrite nitrogen, pH, free chlorine, and ammonia nitrogen). These findings demonstrate the prevalence and persistence of ARGs in intensive fish farming in southern China. This suggests that ARG levels and microbiological community composition in aquaculture should be conventionally determined to assess potential risks to public health.

Effects of Dietary Red Grape Extract on the Quality Traits in Juvenile European Sea Bass (Dicentrarchus labrax L.).

Intensive fish farming is responsible for the occurrence of various stressors that negatively affect the health of cultured animals. Polyphenols are plant-derived compounds with biological activities and positive influences on the performances and immunity of fish. The aim of the present study was to evaluate the effects of dietary inclusion of a polyphenol extract obtained from Nero di Troia red grape on the quality of farmed sea bass (Dicentrarchus labrax) fillets. Three diets were tested: control (n = 90) received a conventional feed, whereas the two experimental groups (n = 90 each) received the control feed supplemented with the red grape polyphenol extract (GPE) at the concentration of 100 (GPE 100) or 200 mg/kg (GPE 200). The two GPE diets lowered (p &lt; 0.05) the red (a *) and yellow (b *) indexes, fillet hardness, and total lipid content. Chewiness, concentration of saturated fatty acids, and the Atherogenic Index were higher (p &lt; 0.05) in the control group; GPE diets increased (p &lt; 0.05) the polyunsaturated fatty acids content. Furthermore, the concentration of malondialdehyde was lower (p &lt; 0.05) in fillets of the GPE groups, thus confirming the antioxidant effect of the red grape extract and its effectiveness in preventing lipid oxidation.

Piscicultura intensiva: alterações na qualidade da água e a relação com a comunidade zooplanctônica

Abstract Aim This study aimed to evaluate the interference of intensive fish farming in the physicochemical variables of water and in the zooplankton community from a tilapia (Oreochromis niloticus Linnaeus, 1758) pond in southern Brazil. In addition, it was verified whether the analyzed zooplankton groups could be bioindicators of changes in the quality of pond water. Methods The water and zooplankton sample collections were carried out monthly in different places of the pond: at the water supply site (affluent), in the middle of the pond and at the water outlet site (effluent). Analyzes related to nitrogen series (total nitrogen, total ammonia, nitrite + nitrate), dissolved oxygen, total hardness, total alkalinity, total phosphorus, pH, turbidity and water temperature were performed at all sampling sites. In addition, the density of the zooplankton groups Copepoda (adults and nauplii), Rotifera and Cladocera was determined. Results Regarding the changes between the quality variables of the affluent and effluent water of the pond, the outlet water showed a significant increase only in the variable total alkalinity. Rotifers were the most abundant organisms, and nauplii Copepoda showed a significant increase in the density of organisms in the middle of the pond compared to the inlet water. Both the redundancy analysis (RDA) and the Spearman correlation matrix revealed that zooplanktonic groups are associated with certain physicochemical variables of the water. According to the Analysis of Indicator Species (IndVal), the evaluated organisms are not related to bioindicator species in this environment. Conclusions Therefore, intensive production of O. niloticus caused changes only in the total alkalinity of the pond water. The zooplanktonic organisms correlated with the physicochemical variables of the water and between the groups, and did not show potential for bioindicators of water quality in the different locations of the pond.