Search Results (864)

Selenium (Se) is an essential trace element critical for animal growth and immune function. This study investigated the dietary selenium requirement of juvenile large yellow croaker (Larimichthys crocea) through an 8-week feeding trial. Five experimental diets were formulated by supplementing a basal diet with selenium polysaccharides (Se-PS) at 0, 20, 30, 40, and 50 mg/kg, resulting in analyzed Se concentrations of 0.35, 0.54, 0.71, 0.93, and 1.11 mg/kg, respectively. The results demonstrated that growth performance and feed efficiency improved with increasing dietary selenium, peaking at 0.93 mg/kg before declining at higher levels. Antioxidant enzyme activities—superoxide dismutase (SOD) and catalase (CAT)—in serum and liver tissues exhibited a dose-dependent increase, reaching maximal levels at 1.11 mg/kg. Conversely, malondialdehyde (MDA), a marker of oxidative stress, progressively decreased in both serum and liver, attaining its lowest concentration at 1.11 mg/kg, though this did not differ significantly from the 0.93 mg/kg group (p = 0.056). Tissue selenium accumulation was highest at these optimal dietary levels. Based on the growth performance, oxidative stress response, and tissue selenium retention, the recommended dietary selenium requirement for juvenile large yellow croaker is 0.93 mg/kg. These findings highlight the importance of optimal Se supplementation in aquafeeds to enhance growth and physiological health in farmed fish. Full article

The small-spotted catshark and the smooth-hound are cartilaginous, carnivorous fish with similar depth ranges in their habitats. These two species are among the most abundant elasmobranchs in the Adriatic Sea and are frequently caught by local fishermen using longline fishing. Despite their ecological similarities, little is known about the physiological differences in their digestive processes. The study of enzymatic digestion in these ecologically relevant species helps to fill the knowledge gap in the understanding of nutrient processing in cartilaginous fish. Therefore, the aim of this study was to determine, measure and compare the enzymatic activity of alkaline phosphatase, acid phosphatase, non-specific esterase and aminopeptidase. Fish were caught in the central part of the Adriatic Sea between 2021 and 2023. A total of 60 adult individuals were analyzed, with samples taken from six parts of the digestive tract. Histochemical analysis of 1440 slides revealed clear differences in enzyme activity between the two species. In the small-spotted catshark, cellular protein degradation was most pronounced in esophagus, posterior stomach and rectum, whereas in the smooth-hound, it was concentrated in posterior stomach and spiral intestine. Cellular digestion of lipids in the small-spotted catshark appears to occur primarily in the stomach. The results of this study provide new insights into the distribution of cellular digestive enzymes in cartilaginous fish and emphasize the importance of studying the entire digestive tract as an integrated system rather than focusing on individual parts. This study fills an important knowledge gap and contributes to a deeper understanding of digestive physiology, which in turn has implications for species conservation and biological variability. Full article

The stomach has been a highly conserved organ throughout vertebrate evolution; however, there are now over 20 lineages composed of monotremes, lungfish and teleost fish displaying a secondary loss of stomach function and morphology. This “agastric phenotype” has evolved convergently and is typified by a loss of gastric glands and gastric acid secretion and a near-to-complete loss of storage capacity of the stomach. All agastric species have lost the genes for gastric enzymes (Pga and Pgc) and proton pump subunits (Atp4a and Atp4b), and gastrin (Gast) has been lost in monotremes. As a key gastric hormone, the conservation of gastrin has not yet been investigated in the lungfish or agastric teleosts, and it is unclear how the loss of gastrin affects the evolution and selection of the native receptor (Cckbr), gastrin-releasing peptide (Grp) and gastrin-releasing peptide receptor (Grpr) in vertebrates. Furthermore, there are still many genes implicated in gastric development and function which have yet to be associated with the agastric phenotype. We analysed the evolution, selection and conservation of the gastrin pathway and a novel gastric gene repertoire (Gkn1, Gkn2, Tff1, Tff2, Vsig1 and Anxa10) to determine the correlation with the agastric phenotype. We found that the loss of gastrin or its associated genes does not correlate with the agastric phenotype, and their conservation is due to multiple pleiotropic roles throughout vertebrate evolution. We found a loss of the gastric gene repertoire in the agastric phenotype, except in the echidna, which retained several genes (Gkn1, Tff2 and Vsig1). Our findings suggest that the gastrin physiological pathway evolved differently in pleiotropic roles throughout vertebrate evolution and support the convergent evolution of the agastric phenotype through shared independent gene-loss events. Full article

The Anti-Müllerian hormone (AMH) is widely recognized for promoting Müllerian duct regression in higher vertebrates and regulating key reproductive functions like steroidogenesis, folliculogenesis, and Leydig cell development. In teleost fish, which lack Müllerian ducts, Amh primarily influences male reproductive functions, including sex determination, testis differentiation, and germ cell proliferation. In adult fish, Amh supports gonad development and spermatogenesis, but its role in teleost gonadal physiology remains largely underexplored. This study reveals a novel steroidogenic function in the European sea bass (Dicentrarchus labrax) using in vitro testis culture, in vivo plasmid injection, and cell-based transactivation assays. The Amh-induced significant increase in androgen levels was also confirmed in Japanese medaka (Oryzias latipes) treated with recombinant sea bass Amh. Beyond activating the canonical Smad pathway, Amh also triggered the cAMP/PKA signalling pathway via its cognate type II receptor, Amhr2. Inhibitors of these pathways independently and synergistically counteracted Amh-induced CRE-Luc activity, indicating pathway crosstalk. Moreover, inhibition of the cAMP pathway suppressed Amh-induced androgen production in testis cultures, emphasizing the crucial role of protein kinase A in mediating Amh steroidogenic action. These findings uncover a novel steroidogenic function of Amh in teleosts and highlight its broader role in male reproductive physiology. Full article

Freshwater salinization, an escalating global environmental stressor, poses a significant threat to freshwater biodiversity, including fish communities. This study investigates the grass carp (Ctenopharyngodon idellus), a species with the highest aquaculture output in China, to elucidate the molecular underpinnings of its physiological adaptations to fluctuating salinity gradients. We used high-throughput mRNA sequencing and differential gene expression profiling to analyze transcriptional dynamics in intestinal and kidney tissues of grass carp exposed to heterogeneous salinity stressors. Concurrent serum biochemical analyses showed salinity stress significantly increased Na⁺, Cl⁻, and osmolarity, while decreasing lactate and glucose. Salinity stress exerted a profound impact on the global transcriptomic landscape of grass carp. A substantial number of co-regulated differentially expressed genes (DEGs) in kidney and intestinal tissues were enriched in immune and metabolic pathways. Specifically, genes associated with antigen processing and presentation (e.g., cd4-1, calr3b) and apoptosis (e.g., caspase17, pik3ca) exhibited upregulated expression, whereas genes involved in gluconeogenesis/glycolysis (e.g., hk2, pck2) were downregulated. KEGG pathway enrichment analyses revealed that metabolic and cellular structural pathways were predominantly enriched in intestinal tissues, while kidney tissues showed preferential enrichment of immune and apoptotic pathways. Rigorous validation of RNA-seq data via qPCR confirmed the robustness and cross-platform consistency of the findings. This study investigated the core transcriptional and physiological mechanisms regulating grass carp’s response to salinity stress, providing a theoretical foundation for research into grass carp’s resistance to salinity stress and the development of salt-tolerant varieties. Full article

The ten-year fishing ban on the Yangtze River aims to restore aquatic biodiversity and rebuild fishery resources. Megalobrama skolkovii, a key species in the basin, was investigated using 2024 data to provide a preliminary assessment of its population structure, stock dynamics, and early recovery. Age analysis (n = 243) showed that 1–6-year-olds were dominated by fish aged 3 (35%), with few older than 4, indicating moderate structural truncation. Growth parameters modeled by the von Bertalanffy Growth Function yielded L_∞ = 61.89 cm and k = 0.25 year⁻¹, with a weight–growth inflection age of 4.4 years. Natural mortality (M = 0.48 year⁻¹) was estimated using Pauly’s empirical formula, and total mortality (Z = 0.55 year⁻¹) was estimated from the catch curve analysis. While fishing mortality (F) was statistically indistinguishable from zero, a plausible low-intensity fishing scenario was explored to assess potential impacts of residual activities. Length-based indicators (LBIs) showed P_mat = 46.05%, P_opt = 9.51%, and P_mega = 6.88%, suggesting reproductive recovery but incomplete structural restoration. These preliminary findings reveal an asymmetrical recovery trajectory, whereby physiological improvements and enhanced recruitment have occurred, yet full structural restoration remains incomplete. This underscores the need for continued, long-term conservation and monitoring to support population resilience. Full article

Climate change is disrupting marine ecosystems, necessitating a deeper understanding of environmental and fishing-related impacts on exploited species. This study examines the effects of physical factors (temperature, thermal anomalies, salinity, seabed conditions), biogeochemical elements (pH, oxygen levels, nutrients, primary production), and fishing pressure on the biomass of commercially important species in the Alboran Sea from 1999 to 2022. Data were sourced from the Copernicus observational program, focusing on the geographical sub-area 1 (GSA-1) zone across three depth ranges. Generalized Additive Models were applied for analysis. Rising temperatures and seasonal anomalies have largely negative effects, disrupting species’ physiological balance. Changes in water quality, including improved nutrient and oxygen concentrations, have yielded complex ecological responses. Fishing indices highlight the vulnerability of small pelagic fish to climate change and overfishing, underscoring their economic and ecological significance. These findings stress the urgent need for ecosystem-based management strategies that integrate climate change impacts to ensure sustainable marine resource management. Full article

Global marine coastal aquaculture increased by 6.7 million tons in 2024, with whiteleg shrimp (Penaeus vannamei) dominating crustacean production. However, reliance on a single species raises sustainability concerns, particularly in the face of climate change. Diversifying shrimp farming by cultivating native species, such as the European brown shrimp (Crangon crangon), presents an opportunity to develop a sustainable blue bioeconomy in Europe. C. crangon holds significant commercial value, yet overexploitation has led to population declines. Integrated Multi-Trophic Aquaculture (IMTA) offers a viable solution by utilizing fish farm wastewater as a nutrient source, reducing both costs and environmental impact. Research efforts in Germany and other European nations are exploring IMTA’s potential by co-culturing shrimp with species like sea bream, sea bass, and salmon. The physiological adaptability and omnivorous diet of C. crangon further support its viability in aquaculture. However, critical knowledge gaps remain regarding its lipid metabolism, early ontogeny, and reproductive biology—factors essential for optimizing captive breeding. Future interdisciplinary research should refine larval culture techniques and develop sustainable co-culture models. Expanding C. crangon aquaculture aligns with the UN’s Sustainable Development Goals by enhancing food security, ecosystem resilience, and economic stability while reducing Europe’s reliance on seafood imports. Full article

Temperature fluctuations caused by climate change and global warming pose a threat to fish. The burbot (lota lota) population is particularly sensitive to increased water temperature, but the systematic impacts of high-temperature exposure on their liver and intestinal health remain unclear. In January of 2025, we collected wild adult burbot individuals from the Ussuri River (water temperature: about 2 °C), China. The burbot were exposed to 2 °C, 7 °C, 12 °C, 17 °C, and 22 °C environments for 96 h; then, the liver and intestinal contents were subsequently collected for histopathology observation, immunohistochemistry, biochemical index assessment, and transcriptome/16S rDNA sequencing analysis. There was obvious liver damage including hepatocyte necrosis, fat vacuoles, and cellular peripheral nuclei. Superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GSH-Px) activities were elevated and subsequently decreased. Additionally, the malondialdehyde (MDA) level significantly increased with increasing temperature. These results indicate that 7 °C (heat stress temperature), 12 °C (tipping point for normal physiological metabolism status), 17 °C (tipping point for individual deaths), and 22 °C (thermal limit) are critical temperatures in terms of the physiological response of burbot during their breeding period. In the hepatic transcriptome profiling, 6538 differentially expressed genes (DEGs) were identified, while KEGG enrichment analysis showed that high-temperature stress could affect normal liver function by regulating energy metabolism, immune, and apoptosis-related pathways. Microbiomics also revealed that acute heat stress could change the intestinal microbe community structure. Additionally, correlation analysis suggested potential regulatory relationships between intestinal microbe taxa and immune/apoptosis-related DEGs in the liver. This study revealed the potential impact of environmental water temperature changes in cold habitats in winter on the physiological adaptability of burbot during the breeding period and provides new insights for the ecological protection of burbot in the context of global climate change and habitat warming. Full article

The intersection of sports and natural forests and green spaces represents an emerging interdisciplinary field with implications for public health, environmental science, and sustainable land management and refers to the variety of cultural ecosystem services demanded by people from ecosystems. This manuscript presents a systematic bibliometric and thematic analysis of 148 publications for the period 1993–2024 identified through Web of Science and Scopus, aiming to evaluate the current state of research on sports activities conducted in natural forest environments. Findings indicated a marked increase in scientific interest of this topic over the past two decades, with key contributions from countries such as England, Germany, China, and the United States. Researchers most frequently examined sports such as hiking, trail running, mountain biking, and orienteering for their capacity to provide physiological and psychological benefits, reduce stress, and enhance mental well-being. The literature analysis highlights ecological concerns, particularly those associated with habitat disturbance, biodiversity loss, and conflicts between recreation and conservation. Six principal research themes were identified: sports in urban forests, sports tourism, hunting and fishing, recreational sports, health benefits, and environmental impacts. Keyword and co-authorship analyses revealed a multidisciplinary knowledge base with evolving thematic focuses. In conclusion, the need for integrated approaches that incorporate ecological impact assessment, stakeholder perspectives, and adaptive forest governance to ensure sustainable recreational use of natural forest ecosystems is underlined. Full article

Environmental enrichment is essential for promoting species-specific behaviors and enhancing the welfare of zoo-housed animals. This study examined the behavioral responses of two juvenile male binturongs (Arctictis binturong) at the Minnesota Zoo to three enrichment stimuli: lavender oil (olfactory), thawed fish (olfactory and dietary), and hard-boiled egg (olfactory and dietary). Their behaviors were recorded using scan sampling before and after enrichment exposure, focusing on locomotion, foraging, resting, and visitor visibility. Food-based enrichments, particularly the hard-boiled egg, significantly increased foraging behavior, while lavender oil and thawed fish produced minimal behavioral changes. Locomotion and visibility remained stable across the conditions, although a slight increase in resting was observed with lavender oil. No evidence of scent-marking disruption was noted, and individual differences appeared to influence inactivity levels. These findings highlight the potential of biologically relevant, food-based enrichment to stimulate natural behaviors in binturongs and emphasize the importance of species-specific enrichment strategies. Future research should explore a broader range of olfactory cues, assess long-term behavioral responses, and incorporate physiological measures to further evaluate enrichment impacts on binturong welfare. Full article

Tebuconazole (TBZ), a triazole-class fungicide widely used in agriculture, is frequently detected in aquatic environments due to runoff and leaching, where it poses a threat to non-target aquatic organisms. This study investigates the acute toxicity of TBZ on juvenile rainbow trout (Oncorhynchus mykiss), a commercially important cold-water fish species. The 96 h LC₅₀ value was determined to be 9.05 mg/L using probit analysis. In addition to mortality, the physiological responses of fish exposed to both LC₅₀ and maximum tolerance concentration (MTC; 6 mg/L) were evaluated through haematological and histological assessments. TBZ exposure significantly suppressed key haematological parameters, particularly WBC, RBC, HGB, HCT, and LYM, indicating immunosuppression and potential hypoxia. Histological examination revealed progressive and regressive damage in gill tissues, including epithelial lifting, hyperplasia, and hypertrophy, which were more severe in the LC₅₀ group. These alterations were quantified using a semi-quantitative scoring system. Additionally, significant changes in biochemical parameters such as ALT, AST, creatinine, total protein, and glucose levels were observed, further indicating hepatic and renal dysfunctions induced by TBZ exposure. The findings demonstrate that TBZ exposure induces substantial physiological and structural impairments in rainbow trout, highlighting the importance of assessing the ecological risks of fungicide contamination in aquatic environments. The study also provides a dose–response model that can be used to estimate mortality risk in aquaculture operations exposed to TBZ. Full article

A circular tri-trophic system integrating aquaponics, i.e., combined cultivation of crops and fish, with insect rearing is presented for lettuce cultivation. The nutrition cycle among crops, insects and fish turns waste into resource, thereby increasing the sustainability of this food production system. A comprehensive evaluation of the system’s efficiency was performed, including the growth, functional and resource use efficiency traits of lettuce, the dynamics of which were followed in a pilot-scale aquaponics greenhouse, under three treatments: conventional hydroponics (HP) as the control, coupled aquaponics (CAP) with crops irrigated with fish-derived water, and decoupled aquaponics (DCAP), where fish-derived water was amended with fertilizers to reach the HP target. The main findings indicate comparable physiological performance between DCAP and HP, despite the slightly lower yield observed in the former. The CAP treatment exhibited a significant decrease in biomass accumulation and functional impairments, which were attributed to reduced nutrient levels in lettuce leaves. The DCAP treatment exhibited a 180% increase in fertilizer use efficiency compared to the HP treatment. We conclude that the tri-trophic cropping system with the implementation of DCAP variant is an effective system that enables the combined production of crops and fish, the latter being fed with sustainably derived insect protein. The tri-trophic system improves the environmental impact and sustainability of lettuce production, while making circularity feasible. Full article

Members of the genus Nemipterus are economically important fish species distributed in the tropical and subtropical Indo-West Pacific region. The majority of species in this genus inhabit waters with sandy–muddy substrates on the continental shelf, although different species are found at slightly varying water depths. In this study, we sequenced seven species within the genus Nemipterus after identifying the specimens using complementary morphological analysis and DNA barcoding. Each species yielded over 40,000,000 clean reads, totaling over 300,000,000 clean reads across the seven species. A total of 276,389 unigenes were obtained after de novo assembly and a total of 168,010 (60.79%) unigenes were annotated in the protein database. The comprehensive functional annotation based on the KOG, GO, and KEGG databases revealed that these unigenes are mainly associated with numerous physiological, metabolic, and molecular processes, and that the seven species exhibit similarity in these aspects. By constructing a phylogenetic tree and conducting divergence time analysis, we found that N. bathybius and N. virgatus diverged most recently, approximately during the Neogene Period (14.9 Mya). Compared with other species, N. bathybius and N. virgatus are distributed in deeper water layers. Therefore, we conducted selection pressure analysis using these two species as the foreground branches and identified several environmental-responsive genes. The results indicate that genes such as aqp1, arrdc3, ISP2, Hip, ndufa1, ndufa3, pcyt1a, ctsk, col6a2, casp2 exhibit faster evolutionary rates during long-term adaptation to deep-water environments. Specifically, these genes are considered to be associated with adaptation to aquatic osmoregulation, temperature fluctuations, and skeletal development. This comprehensive analysis provides valuable insights into the evolutionary biology and environmental adaptability of threadfin breams, contributing to the conservation and sustainable management of these species. Full article

The climbing perch, Anabas testudineus, is one of the most widely distributed freshwater amphibious fishes in South and Southeast Asia, exhibiting terrestrial movements. Our experimental study aimed to investigate endocrinological and biochemical changes in the blood of climbing perch associated with their terrestrial movements. To achieve this, the fish were divided into two groups: one group was exposed to aquatic conditions for twenty minutes, while the other group was subjected to terrestrial conditions for the same duration through rapid water level decrease. In terrestrial conditions, the fish predominantly exhibit movements on land, whereas in aquatic environments, they primarily remain immobile or swim. Elevated levels of stress-induced cortisol and glucose after short-term exposure indicate a high-stress response involving both neuroendocrine and metabolic mechanisms. Changes in the activity of aspartate aminotransferase and increased concentrations of triglycerides in the blood serum suggest energy mobilization through aerobic metabolic pathways. Extreme environmental changes did not affect thyroid axis function, including deiodination, thereby maintaining essential physiological activities under new conditions. Additionally, the anaerobic metabolic pathway appears to be minimally utilized at the onset of terrestrial movement, as no significant changes in lactate dehydrogenase concentrations were observed. Overall, the terrestrial movements of the climbing perch are likely predominantly forced and associated with high stress. Full article