Search Results (92)

Monitoring trace metals in commercially important fish species provides an early warning of anthropogenic contamination and potential risk to consumers. This study semi-quantified and quantified essential, non-essential, and toxic elements in the muscle of wild meagre (Argyrosomus regius) captured in the Tagus estuary (Portugal), which is used as a nursery and spawning aggregation area. Dry muscle was microwave-digested and analyzed using inductively coupled plasma–optical emission spectroscopy. Semi-quantified screening detected Al, B, Ca, Fe, K, Mg, Na, P, S, Si, Sr, and Ti, and eight elements were determined using multielement calibration (As, Cr, Cu, Hg, Mn, Ni, Se, and Zn); Cd, Pb (toxic elements), Co, and Mo were not detected in this study. Arsenic was detected in all individuals, with a minimum value of 0.348 mg/kg wet weight. A mercury level above the European Commission regulatory limit (0.5 mg/kg wet weight) was only detected in one individual, corresponding to 2% of the samples. Although other metals remain well below regulatory limits, continued biomonitoring is recommended to track temporal trends and safeguard seafood safety in transitional coastal systems, which is important for commercially relevant fish species. Full article

Germ cell xenotransplantation is a promising tool for enhancing aquaculture production and supporting the conservation of declining fish species. A major limitation is the reliable identification of germ stem cells, which remains challenging due to the scarcity of validated molecular markers. This study assessed the suitability of different immunohistochemical approaches for identifying ovarian germ stem cells (OGSCs) in three Mediterranean species of commercial interest: European hake (Merluccius merluccius), meagre (Argyrosomus regius), and flathead grey mullet (Mugil cephalus). Among the antibodies tested (anti-OCT4, anti-VASA, anti-Sox2), only anti-VASA and anti-Sox2 labeled cells with morphological features consistent with OGSCs, although staining intensity, specificity, and cross-reactivity with early oocytes varied across species. In parallel, preliminary protocols for OGSC isolation and in vitro proliferation were developed for European hake and meagre. Enzymatic dissociation with collagenase, followed by Ficoll-Paque density separation and culture in Leibovitz’s L-15 medium supplemented with 2% fetal bovine serum at 25 °C, resulted in the highest OGSC recovery and detectable increases in proliferating cells. A sequential pre-plating step enhanced enrichment in meagre but caused substantial cell loss in hake. Overall, this study provides a comparative evaluation of female germline stem cell markers in these species, contributing to future surrogate reproduction and germplasm conservation strategies. Full article

Due to their interesting physicochemical and bioactive properties, regenerated fibres (including cellulose and collagen regenerated fibres) have been considered attractive biomaterials for biomedical applications. These regenerated fibres have an altered molecular arrangement compared to the native fibres and exhibit unique properties. Despite their distinctive structural characteristics, a meagre amount of research explores their potential for the development of tissue-engineering bio-composites. This work focuses on exploring the promise of cellulose and collagen-based regenerated fibres in tissue-regeneration bio-composite development. Initially, the work investigates the similarities and dissimilarities between the collagen and cellulose structures, which are linked to their specific properties, such as crystallinity, chemical characteristics, and mechanical properties. It then delves deeper into their molecular structural reassembly and various aspects of the already reported bio-composites developed using them. Finally, their promise in the development of tissue-engineering bio-composites is explored through a meticulous comparative analysis of their advantages and challenges. It was found that efficient biodegradability is one of the key advantages of regenerated fibres, whereas difficulty in processing presents a significant disadvantage. Despite these facts, regenerated fibres can incorporate enhanced and desired properties into the bio-composite matrix, which could lead to tissue-specific bio-regenerative applications. Full article

Aquaculture is expanding rapidly worldwide, but its sustainability is threatened by intensive production practices, environmental stressors and recurrent disease outbreaks. Natural feed additives are increasingly studied as alternatives to antibiotics and synthetic compounds. Among them, bee-derived products—pollen, bee bread, propolis, royal jelly, honey and fermented derivatives—represent a promising resource due to their richness in proteins, amino acids, fatty acids, vitamins, flavonoids and phenolic compounds with demonstrated antioxidant, antimicrobial and immunostimulant properties. Evidence from studies on species such as Nile tilapia, rainbow trout, European sea bass, meagre and African catfish indicates that dietary supplementation with bee products can improve growth performance, immune and antioxidant responses, stress tolerance and resistance to bacterial infections while, in some cases, enhancing the nutritional value and shelf-life of fish products. Prominent examples include ~45% higher growth in African catfish with 10–30 g kg⁻¹ bee pollen, up to 93% protection in Nile tilapia fed 25 g kg⁻¹ pollen against Aeromonas hydrophila, and increased trout fillet carotenoids with pollen-derived pigments (with overall growth unchanged and pigmentation lower than synthetic astaxanthin). Conversely, meagre fed 20–40 g kg⁻¹ raw pollen showed reduced growth and digestibility with elevated intestinal stress markers, underscoring species- and dose-specific responses. Nevertheless, the available data remain fragmented and heterogeneous, reflecting differences in product type, origin, dosage and experimental design. This review critically analyses the current knowledge on bee products in aquaculture nutrition, identifies the main gaps and limitations, and outlines future research directions. By linking fish physiology, nutritional strategies and product quality, bee-derived products emerge as innovative tools for promoting fish health and resilience in sustainable aquaculture. Full article

This study presents, for the first time, the occurrence and community structure of wild fish inside marine aquaculture cages of gilthead seabream (Sparus aurata), European sea bass (Dicentrarchus labrax), greater amberjack (Seriola dumerili), meagre (Argyrosomus regius), and common dentex (Dentex dentex). Coexistence of farmed and wild fish was observed only in cages of gilthead seabream and European sea bass, with wild fish constituting 0.08% of the total sampled fish biomass. Twelve wild fish species from five families were recorded: Carangidae, Clupeidae, Mugilidae, Moronidae, and Sparidae. Bogue (Boops boops) and jack mackerel (Trachurus sp.) were the most abundant. Multivariate analysis indicated that location significantly influenced the wild fish community composition, while reared species and farming duration, along with their interaction, had no significant effect. Descriptive comparisons suggested potential differences in biometric traits of bogue and jack mackerel between reared species and farming duration. The findings highlight the need for further research on wild fish in cages to better understand the potential health and biosecurity risks they may pose. Full article

To overcome reproductive dysfunctions, recombinant gonadotropin hormones have been synthesised in different fish species. We were interested in gaining further insight into the effects of recombinant follicle-stimulating hormone (rFsh) in meagre Argyrosomus regius spermatogenesis and in improving the existing knowledge on the role of testicular apoptosis. Germ cell composition and testicular apoptosis were compared in pre-pubertal fish treated with rFsh (PreP-Fsh) and controls (PreP-C), and adult meagre with testes in the proliferative (Adult-Pro) and meiotic (Adult-Meio) spermatogenesis phases. A lower density of committed spermatogonia was observed in PreP-Fsh compared with PreP-C and in Adult-Meio compared with Adult-Pro. In pre-pubertal fish and in Adult-Pro, apoptosis affected mainly individual germ cells and Sertoli cells. In Adult-Meio, a high number of cysts containing apoptotic germ cells was observed, and apoptosis often involved entire clones of germ cells. rFsh reduced testicular apoptosis in pre-pubertal fish, whereas the advancement of spermatogenesis in adults was associated with an increased density of apoptotic cells. The present study corroborated previous observations on the effects of rFsh on spermatogenesis in pre-pubertal meagre and provided further insights on the changing role of apoptosis in the pre-pubertal phase versus different phases of spermatogenesis. Full article

Low seawater temperatures are expected to depress fish growth in aquaculture. However, recent evidence suggests diet composition may offer mitigation for some species. This study evaluated the impact of different diets on juvenile meagre (Argyrosomus regius) in cage farming at low seawater temperatures (average 15.19 °C), conditions known to typically suppress meagre growth. Three replicated groups of fish (initial weight ≈ 107 g) were fed for six months either sardines (group A) or commercial pellets (groups B/C, with group C moisturized). The results demonstrate that the nutritional profile of sardines effectively mitigates cold-induced growth reduction in meagre. While pellet-fed meagre experienced expected growth depression, sardine-fed meagre exhibited a doubled temperature growth coefficient (TGC) and an 80% higher final average weight than the pellet groups (A: 346.13 g, B: 194.44 g, C: 188.93 g). Full article

As aquaculture expands, plant-based feeds are increasingly used, but some fish species poorly tolerate them, affecting health and growth. Probiotics can help counter these effects by improving digestion, nutrient absorption, and immunity. This study evaluated the effect of dietary incorporation of Bacillus subtilis FI99 on the intestinal health of meagre. A nutritional challenge was performed with a practical control diet and three diets higher in plant-based ingredients: one without probiotic and two with probiotic incorporated at 1 × 10⁹ CFU g⁻¹ and 5.5 × 10¹¹ CFU g⁻¹. Histomorphological analysis was used to assess intestinal health and validate previously established machine learning models in predicting fish nutritional status. No differences were observed in zootechnical performance and biometric indexes. Most effects were observed in the anterior intestinal section, where probiotics improved total area, lumen area, lumen maximum diameter, total maximum diameter, villi area, and villi + lumen area. Additionally, probiotics improved supranuclear vacuole size, eosinophilic granulocytes, and intraepithelial leukocytes presence in anterior and intermediate sections. Machine learning models could not accurately predict the nutritional status of fish. Overall, the study indicates that dietary inclusion of B. subtilis enhances the intestinal health of meagre fed plant-based diets. Machine learning models require further development for improved accuracy. Full article

Meagre (Argyrosomus regius) is an important species in aquaculture, with size and flesh quality playing key roles in its production and marketability. This study aimed to examine the relationship between growth and flesh quality parameters, including fatty acid content (FA), total antioxidant capacity (TOAC), superoxide dismutase (SOD), lipid oxidation (LO), muscle cellularity (MC), and filleting yield (FY) during cold storage. Fish from the same hatchery raised under identical conditions showed size variation after 12 months. Fish below 600 g were classified as slow growing (SG), while those above 1000 g were classified as fast-growing (FG). The results showed that FG fish had higher body weight, moisture, and FY but exhibited lower levels of fat and polyunsaturated fatty acids (PUFA). SG fish had higher TOAC and SOD activity, which significantly declined during cold storage in both groups but remained higher in SG fish. Despite the higher lipid content in SG fish, no significant differences in malondialdehyde (MDA) levels, an indicator of LO, were observed between the two groups, suggesting that the elevated antioxidant defenses in SG fish mitigated lipid peroxidation. This study underscores intrinsic antioxidants’ potential to preserve lipid quality of fish fillets during cold storage. Full article

Aquaculture is a globally widespread practice and the world’s fastest-growing food sector and requires technological advances to both increase productivity and minimize environmental impacts. Monitoring the sector is one of the priorities of state governments, international organizations, such as the Food and Agriculture Organization of the United States (FAO), and the European Commission. Data collection in aquaculture, particularly information on the location, number, and size of production facilities, is challenging due to the time required, the extent of the area to be monitored, the frequent changes in farming infrastructures and licenses, and the lack of automated tools. Such information is usually obtained through direct communications (e.g., phone calls and e-mails) with aquaculture producers and is rarely confirmed with on-site measurements. This study describes an innovative and automated method to obtain data on the number and placement of structures for marine and freshwater finfish farming through a YOLOv4 model trained on high-resolution images. High-resolution images were extracted from Google Maps to test their use with the YOLO model for the identification and geolocation of both land (raceways used in salmonids farming) and sea-based (floating sea cages used in seabream, seabass, and meagre farming) aquaculture systems in Italy. An overall accuracy of approximately 85% of correct object recognition of the target class was achieved. Model accuracy was tested with a dataset that includes images from Tuscany (Italy), where all these farm typologies are represented. The results demonstrate that the approach proposed can identify, characterize, and geolocate sea- and land-based aquaculture structures without performing any post-processing procedure, by directly applying customized deep learning and artificial intelligence algorithms. Full article

The properties of biopolymer films prepared using Southern meagre fish (Argyrosomus hololepidotus) skin gelatin blends, both with and without clove bud extract (CE) at concentrations of 0.3% and 0.7%, were investigated. The addition of CE enhanced the light barrier properties and decreased water vapor permeability from 1.68 to 0.85 (×10⁻¹³ g s⁻¹m⁻¹Pa⁻¹) (p < 0.05) in the films that contained CE. Additionally, the films’ water solubility diminished as the concentration of CE increased (89.20 to 69.04%) (p < 0.05). SEM images revealed a smooth, uniform surface without cracks in the samples both with and without CE, whereas the films that included CE displayed a rougher and denser cross-section. FTIR spectra revealed variations in peaks between the films containing CE and those without it. The incorporation of CE raised the glass transition temperature (51.04 to 58.80 °C) and the melting temperature (124.65 to 141.92 °C) of the films. Additionally, the antioxidant activities, assessed through DPPH free radical scavenging activity (86.97%) and reduction power (λ of 0.85), along with moderate antibacterial activities against four distinct foodborne pathogens, improved with increased concentrations of CE. It can be concluded that phenolic compounds, such as eugenol in the clove extract, facilitated the formation of additional bonds between the peptide helixes of the gelatin, thereby enhancing the properties of the CE-incorporated films. Thus, Southern meagre fish gelatin film containing CE is an effective active packaging biomaterial for seafood products, exhibiting satisfactory properties. Full article

The aquaculture sector is developing sustainability measures to address resource limitations and environmental concerns. A key strategy is replacing fishmeal and fish oil with alternatives that can equally sustain fish health, growth, and water quality. This study compared a standard diet (STD) to an alternative diet (ALT) containing sustainable ingredients, such as plant-based proteins and animal by-products, for meagre raised in earthen ponds within a polyculture system. Over 150 days, 5400 meagre juveniles (174.9 ± 32.8 g) were fed these diets. Fish on the ALT diet showed superior growth, likely due to higher dietary protein content and reduced protein degradation in liver and muscle, leading to increased protein content and reduced levels of dry matter, lipid, ash, energy, and phosphorous. While muscle cohesiveness was affected, fiber area and density were unchanged. ALT-fed fish exhibited higher saturated (SFA) and polyunsaturated (PUFA) fatty acids, reflecting the diet. Water quality indicators, including ammonia, nitrites, nitrates, and phosphates, were similar across diets, though chlorophyll a was higher in ponds with STD-fed fish. Overall, the ALT diet emerges as a sustainable alternative to the STD diet, maintaining or enhancing protein levels while reducing fishmeal usage. This approach effectively supports meagre growth and fillet quality without significant additional environmental impact. Full article

The gut is the first organ to contact food, and it is often the target of nutrition studies performed on aquaculture fish. Histological analysis reveals morphological changes in fish intestines caused by ingredients in formulated feeds. However, this type of analysis is mainly based on a semi-quantitative approach, often restricted to specialized researchers, and may provide inconsistent results between studies. This study addresses these limitations by combining semi-quantitative and quantitative features to characterize the anterior, intermediate, and distal sections of the intestine of meagre (Argyrosomus regius) subjected to different nutritional status. Collected data were used to build machine learning models, select the most accurate ones, and identify key features for predicting malnutrition. Logistic regression, support vector machines, and ensemble stacking performed best across all intestinal sections. Combining semi-quantitative and quantitative features yielded the best predictions, with villi number, density and area, and goblet cell count being the most crucial for the classification task. When considering the distal intestine alone, semi-quantitative features outperformed quantitative ones. The intermediate section of the intestine showed the best model accuracy, indicating higher sensitivity to nutritional changes. These results demonstrate the potential of machine learning models to streamline histomorphological analyses to evaluate nutritional status, making them more accessible and standard across users. Full article

Meagre (Argyrosomus regius) is one of the fast-growing species considered for sustainable aquaculture development along the Mediterranean and Eastern Atlantic coasts. The emergence of Systemic Granulomatosis (SG), a disease marked by multiple granulomas in various tissues, poses a significant challenge in meagre aquaculture. In the current study, we investigate the association of Mycobacterium spp. and SG in offshore aquaculture facilities in Sardinia, Italy. A total of 34 adult seemingly healthy meagre were arbitrarily collected and analyzed, combining histological, microbiological, molecular, metagenomics, and in situ techniques to investigate the presence of pathogens. Ziehl–Neelsen (ZN), periodic acid–schiff (PAS), and Giemsa stains were performed for the detection of acid-fast bacteria, common parasites, and fungi within granulomas, respectively. Granulomas were detected in 91% (31/34) of fish. The affected organs were kidney (88%), liver (47%), heart (41%), intestine (17.6%), and brain (5%). Acid-fast staining, along with Mycobacterium spp. specific quantitative PCR (qPCR), in situ hybridization (ISH) assay, and microbiological analyses showed negative results for the detection of Mycobacterium spp. and other bacteria implicated in granuloma formation. However, PCR amplification and sequencing of the 65-kDa heat shock protein gene revealed the presence of M. chelonae in 13% of both formalin-fixed and frozen liver tissues. Bacterial isolation failed to detect nontuberculous mycobacteria (NTM) and other bacteria typically associated with granulomas. Consistently, the use of an M. chelonae-specific probe in ISH failed to identify this bacterial species in granulomas. Collectively, results do not support the role of M. chelonae in the development of granulomas and suggest rejecting the hypothesis of a potential link between NTM and SG. Full article

This study aimed to investigate the morphological characteristics and phylogenetic relationships of three new species of Tropicoporus from the southern parts of India. The analyses of the ITS and nLSU regions revealed the novelty of these species, which have been named T. pannaensis, T. subindicus, and T. xerophyticus. All three species possess pileate basidiomes, a monomitic hyphal system in the context, and the presence of cystidioles and setae. However, they differ significantly in their phylogenetic placements and other morpho-taxonomic features. Tropicoporus pannaensis is characterized by a meagrely ungulate basidiome, indistinct zones, and an obtuse margin. Tropicoporus subindicus has a triquetrous basidiome and a radially cracked, crusted pileal surface with an acute margin, while T. xerophyticus is distinguished by an imbricate, perennial basidiome with an abundantly warted pileal surface. A phylogenetic tree is provided to show the placement of the three new species, along with detailed descriptions and illustrations. Additionally, a key for the identification of the Asian species of Tropicoporus is presented. Full article