Abstract: Water pollution poses a severe threat to global aquatic ecosystems, yet the adaptive mechanisms of aquatic organisms under such stress remain poorly understood. This study investigates the physiological and transcriptomic responses of the freshwater hydrozoan Craspedacusta sowerbii to two prevalent water pollutants: the antibiotic sulfamethoxazole (SMZ, 20 μM) and the heavy metal cadmium sulfate (Cd, 10 μM). Physiological observations revealed that SMZ exposure reduced motility and induced body shrinkage, while Cd exposure caused complete loss of motility, physical disintegration, and mortality within 24 hours. Transcriptomic analysis via RNA-seq identified significant alterations in gene expression patterns. SMZ exposure primarily up-regulated genes associated with oxidative stress, apoptosis, and immune responses, whereas Cd exposure resulted in extensive down-regulation of genes involved in metabolic pathways, cell cycle regulation, and anti-aging processes. Comparative analysis highlighted shared and distinct pathways affected by the two pollutants, including disrupted cell motility, cytokinesis, and molecular transducer activity. Notably, Cd exposure induced more severe transcriptional suppression, correlating with higher mortality. These findings underscore the ecological significance of C. sowerbii as a sensitive indicator of water quality and provide molecular insights into its adaptive strategies under pollution stress. Furthermore, the study offers critical implications for understanding the broader impacts of water pollutants on aquatic biodiversity, emphasizing the need for improved pollution control measures. Future research should focus on long-term multi-pollutant effects, field validation, and cross-species comparative studies to enhance ecological conservation strategies.

Abstract: The kelp genus Eisenia Areschoug is represented by two species in the Southeast Pacific: Eisenia cokeri, distributed in Peru and Chile, and E. gracilis, endemic to Peru. However, the taxonomic distinction between these two species has been questioned. Additionally, it is uncertain whether E. cokeri is conspecific with the Northeast Pacific species E. arborea. To address these issues, we examine, for the first time, the morphology and the molecular phylogenetics of E. cokeri and E. gracilis across their geographic range. Sampling for morphological and molecular analyses was conducted at subtidal zones in five locations in Peru. Furthermore, a locality in Chile was sampled for molecular studies, where E. cokeri was documented. Peruvian Eisenia species exhibited notable differences in morphological characters, including size, holdfast diameter, stipe modifications (e.g., longitudinal division and pseudostipe formation), frond division, frond margins, and roughness, as evidenced by differences in thallus morphometric variables. Phylogenetic analyses using mitochondrial and chloroplast markers revealed three distinct genetic lineages and two endemic species: E. cokeri and E. gracilis from Peru, and a new Eisenia sp. from Chile. Moreover, we confirmed the distinctiveness of E. cokeri from E. arborea and provided updated information on the distribution of E. cokeri and E. gracilis in the Southeast Pacific. These findings are crucial for the management and conservation of these endemic, foundational species.

Abstract: Tardigrades, commonly known as water bears or moss piglets, are microscopic extremophiles famed for their resilience to harsh environments, including extreme temperatures, radiation, and desiccation. Beyond their unique survival traits, recent discoveries of their symbiotic microbial partners open exciting avenues for biotechnological innovation. This review explores the untapped potential of tardigrades and their symbionts as novel sources for next-generation superfoods, cosmetics and pharmaceuticals. Leveraging CRISPR gene-editing technology, we discuss strategies to enhance their nutritional profiles, stress tolerance, and metabolic pathways for sustainable food production. Integrating extremophile biology with cutting-edge genome engineering could revolutionize food systems by introducing robust, nutrient-dense, and environmentally resilient bioresources.

Abstract: Biomarkers are increasingly recognized as essential tools for assessing fish nutrition, stress, health, and environmental interactions in aquaculture, yet little is known about their awareness, use, and perceived value among European stakeholders. This study aimed to characterize current knowledge, applications, barriers, and future needs through a questionnaire-based survey distributed to researchers, industry professionals, and other aquaculture stakeholders across Europe. The survey, conducted via Google Forms, gathered responses from 38 participants representing 17 countries and diverse production systems. Results showed high familiarity with biomarker concepts, particularly those related to stress and health assessment, and identified blood biochemistry, histology, cortisol, oxidative stress markers, and gene expression as the most commonly used indicators, mainly in trout, seabass, and seabream. Although biomarker data occasionally informed decisions—especially regarding health treatments and feed adjustments—their wider adoption was constrained by high analytical costs, limited technical capacity, and lack of standardized protocols. Respondents emphasized the need for training, user-friendly diagnostic tools, funding support, and harmonized methodologies to enhance implementation. Overall, findings reveal strong interest and clear potential for expanded biomarker integration in European aquaculture, while highlighting critical gaps that must be addressed to support evidence-based and sustainable farm management.

Abstract: Seaweeds are photosynthetic organisms with ecological, social, and economic significance, and they serve as effective bioindicators in marine ecosystems. This study assessed trace element concentrations in beach-cast seaweeds collected from four beaches along the Espírito Santo coast in Brazil - an area impacted by mining-related contamination. Samples of Zonaria tournefortii and Sargassum natans, gathered during low tide (July–August 2022), were analyzed for 15 elements. Aluminum (Al), iron (Fe), and magnesium (Mg) were the most abundant (>100 mg/kg), while minor elements included barium (Ba), arsenic (As), zinc (Zn), vanadium (V), nickel (Ni), chromium (Cr), copper (Cu), lead (Pb), cobalt (Co), cadmium (Cd), silver (Ag), and mercury (Hg). Elemental profiles exceeded those reported in other global regions and closely resembled iron ore tailings. These findings - first for beach-cast seaweeds in this region - suggest that the contamination is related to the collapse of the Fundão dam in Mariana, Minas Gerais, which occurred in 2015, resulting in one of the most serious environmental disasters in Brazilian history. The incident released approximately 60 million cubic meters of mining tailings, that traveled approximately 600 km through the Rio Doce Basin, reaching the north of Espírito Santo and arriving at the ocean.

Abstract:

In order to investigate the effects of choline on the synthesis of endogenous phospholipids in Eriocheir sinensis, this experiment was conducted by adding 0%, 0.2% and 0.4% choline to low phospholipid (0% PL) and normal phospholipid (2% PL) diets, respectively, and feeding the crabs with an initial body weight of 0.4 g for 8 weeks. The results showed that diets supplementation with 0.4% choline significantly upregulated the relative mRNA expression of neuropathy target enzyme 1 (nte1), phospholipase A2 (pla2) and phospholipase B (plb) in the low phospholipids condition. In addition, dietary 0.4% choline significantly increased the relative mRNA expression of hepatopancreatic fatty acid binding protein 3 (fabp3), fatty acid transporter protein 4 (fatp4), carnitine palmitoyltransferase-2 (cpt-2), carnitine acetyltransferase (caat), carnitine palmitoyltransferase-1a (cpt-1a) and carnitine palmitoyltransferase-1b (cpt-1b) in juvenile Chinese mitten crab. Dietary 0.2% choline significantly up-regulating the relative expression of fatty acid synthase (fas), and fatty acid elongase 6 (elovl6) mRNA relative expressions in the 2% PL diets. This study shows that dietary supplementation with 0.4% choline could improve phospholipids synthesis of Chinese mitten crab under low phospholipids condition, and 0.2% Choline could improve the decomposition and remodeling of phospholipids in the normal phospholipids condition.

Abstract: This field study was conducted as part of efforts to introduce Integrated Multi-Trophic Aquaculture (IMTA) into Nigeria’s aquaculture system. It examined extant aquatic food production and marketing in three coastal states of Lagos, Ogun, and Ondo before IMTA across 15 Local Government Areas (LGAs) /Local Council Development Areas (LCDAs). Marketing mix practices in coastal aquatic food systems were explored through a structured, qualitative assessment using a multi-value chain perspective. Monthly sales volumes most frequently fell within the 1–5 tonnes range. The local market was dominant, with some sales into the international markets. Respondents asserted that post-harvest was diverse, and some were satisfied with the technology available to preserve their products. Cold storage practices across coastal states were hindered by unreliable power supply. Zero-channel distribution dominated among traders, with over 90% relying on word-of-mouth (WOM) to promote their products. Consumers show a strong preference for the quality of local products and expressed openness to incorporating seaweeds into their purchases. Health benefits and taste were widely recognized as key motivators for purchasing aquatic food products. Findings provide a baseline for IMTA in Nigeria, highlighting existing strengths, market dynamics, and infrastructure gaps that must be addressed to support sustainable integration.

Abstract: Background/objectives: Elastin is a highly hydrophobic extracellular matrix protein responsible for the extensibility and elastic recoil of various organs. The Windkessel effect in blood vessels dampens pressure variations during the cardiac cycle to provide continuous perfusion of tissues. Duplication of the elastin gene in teleost fish led to the neofunctionalization of the ElnB paralog, which confers the uniquely low stiffness of the bulbus arteriosus to protect the fragile gill capillaries from large pressure variations. Methods: We have examined the diversity of elastins in all major fish clades by searching for eln genes in the sequenced genomes. Results: Tetraploid salmonids have two elna genes but a single elnb, except for the tandem duplicated elnb genes in sockeye salmon and lake whitefish, while the tetraploid common carp possesses four elna and elnb genes on separate chromosomes. Rainbow trout showed strong elastin staining in the larval bulbus and ventral aorta, and elnb was highly expressed in the bulbus of juvenile and adult fish. Teleost ElnB differs from the ElnA paralog by containing considerably longer hydrophobic domains. The single elastin in cartilaginous and lobe-finned fish showed high overall hydrophobicity, and no relationship was found between the hydrophobicity levels of fish elastin and the ventral aortic blood pressure. Conclusion: The differential gene expression of teleost elna and elnb during cardiac development probably evolved together with the divergence in the genetic structure that resulted in larger hydrophobic domains of the ElnB paralog and decreases stiffness of bulbus arteriosus.

Abstract:

While Panulirus ornatus is one of the world’s most valuable aquaculture species, its complex feeding behaviour remains a limitation to industry development. Feed texture is central to feeding behaviour and is heavily influenced by the choice of binder. This study investigates binder-induced feed textures that enhance feeding behaviour and apparent feed intake of P. ornatus. Fifty P. ornatus were subjected to five dietary treatments over a 14-day period. Diet 1 (control) was formulated with wheat gluten as binder, while diets 2 to 5 combined wheat gluten with xanthan gum, guar gum, alginate, and transglutaminase, respectively. Feed texture was quantified using a texture analyzer, while feeding behaviour was assessed by EthoVision XT software. Guar gum exhibited the most durable and firmest pellets. However, wheat gluten optimised feeding behaviour, as indicated by the longest cumulative time spent in the feeding zone (87.46 ± 3.63%) and lowest frequency of entries and exits (21.67 ± 2.91 times). Moreover, wheat gluten yielded the highest apparent feed intake (0.98 ± 0.05 %BW/day). Pellets produced with other additional binders resulted in decreased feeding behaviour metrics and apparent feed intake. In summary, wheat gluten binder alone produced a suitable texture, optimising feeding behaviour and apparent feed intake.

Abstract:

Crayfish often become invasive when introduced to new waters. The mid-20th-century commercial import of North American species (e.g., Faxonius limosus, Pacifastacus leniusculus, Procambarus clarkii) into Europe for food, pets, and restocking after crayfish plague, succeeded due to their adaptability, high reproductive rates, and resilience. Extensive baited-trap monitoring of Piedmont lakes allowed us to confirm the occurrence of the Old Non-Indigenous Crayfish Species (F. limosus, P. leniusculus, and P. clarkii), and to record P. clarkii first-ever in three additional lakes (Pistono, San Michele, and Sirio), thereby expanding our knowledge of their distribution in Piedmont freshwaters. Since all detected species are listed as Invasive Alien Species of Union Concern, protecting the ecological integrity of Piedmont’s freshwaters requires coordinated action by member states, regional authorities, policymakers, and water managers to prevent and control their spread, and to improve information sharing. Non-native crayfish occurrence is influenced not only by hydrological and habitat connectivity, and predator–prey interactions, but also by illegal activities that supply the food market.

Abstract:

The red swamp crayfish (Procambarus clarkii) is a globally important freshwater crustacean that exhibits pronounced sexual dimorphism, with males growing faster than females. However, the molecular mechanisms underlying sex differentiation in crustaceans remain poorly understood. In this study, Oxford Nanopore-based Direct RNA Sequencing (DRS) was employed to analyze the gonadal transcriptomes of male and female P. clarkii, identifying 20,001 previously unannotated genes and revealing extensive sex-specific differences in transcript structure, alternative splicing, and RNA modifications. Ovarian transcripts had shorter polyA tails and more frequent alternative splicing, while male gonads showed greater enrichment of m6A and psU modifications in 3' UTR regions. qPCR validation confirmed the sex-biased expression of key candidate genes, including Dmrt7, FR, Fruitless, IAGBP, RDH, and Vtg. Collectively, these findings provide the first comprehensive epitranscriptomic landscape of P. clarkii gonads, underscoring the pivotal role of post-transcriptional regulation in sex determination and offering valuable insights for mono-sex breeding strategies in aquaculture.

Abstract: The tomato hind grouper (Cephalopholis sonnerati) is an emerging aquaculture species, with significant commercial value and promising farming potential. To advance the theoretical framework for artificial breeding, this study systematically investigated embryogenesis, early larval morphology, growth patterns, and heritable traits of the species. Results indicated fertilization and hatching rates of 88.67 ± 3.93% and 79.67 ± 7.55%, respectively, with an average egg diameter of 0.87 ± 0.02 mm. Hatching occurred 22:55 h after fertilization at 24.80 ± 0.70 °C, and the newly hatched larvae measured 2.09 ± 0.12 mm in total length. After 15 months of graded rearing, marked growth disparities were observed among individuals originating from the same clutch, with the fast-growing group weighing 457.12 ± 58.68 g, 2.9 times greater than that of the slow-growing group. These findings underscore the potential of C. sonnerati as a valuable aquaculture species. Future efforts should prioritize enhanced broodstock selection and the development of fast-growing germplasm to increase its cultivation potential.

Abstract:

Information on the food web structure of fish assemblages is necessary for ecosystem-based fishery management. In this study, we investigated spatial and temporal variations in the trophic structure of fish assemblages in the eastern region of the Yellow Sea. We analyzed the species composition, abundance, and δ¹³C and δ¹⁵N values of fish assemblages and their potential food sources collected at the two sites during the four seasons of 2023. Spatial and temporal differences in the abundance and diversity of fish assemblages were observed between the sites and among the seasons. The isotopic values of fish assemblages with isotopic niche indices differed significantly between sites and seasons. In addition, the isotopic niche indices showed different seasonal patterns between the sites. However, the isotopic distributions and niche indices of fish assemblages showed no clear spatial or seasonal trends. These results suggested that the effect of site-specific variability in environmental factors and community characteristics is linked to different ambient environmental conditions. Overall, this study is important for understanding the ecological role of fishery resources and enhancing ecological-based fishery management in the eastern region of the Yellow Sea under severe anthropogenic effects and climate change.

Abstract: Holothuroids play a vital role in nutrient cycling and bioturbation to enhance the marine ecosystem. They enhance the biodiversity for various symbiotic marine organisms by providing essential shelter and spawning grounds. This review focuses on the Class Holothuroidea de Blainville, 1834 (Phylum Echinodermata) in Indian waters, encompassing a total of 187 species organized into 7 orders and 21 families. Notably, the order Holothuriida Miller, Kerr, Paulay, Reich, Wilson, Carvajal & Rouse, 2017, represents the largest proportion of species, accounting for 26.73%. These species are well-distributed across India, with the Andaman and Nicobar Islands exhibiting the highest level of species richness (109 species), followed by the East Coast (102 species), Lakshadweep (39 species), and the West Coast (34 species). Species diversity was assessed using the Shannon-Weiner diversity index. Results indicate that the Andaman and Nicobar Islands (H' = 2.23) and the West Coast (H' = 2.14) demonstrate the highest levels of diversity. This review provides a comprehensive and precise inventory of all Holothuroidea species reported in Indian waters. A checklist is provided to facilitate understanding of the reported species, their systematics, and distribution.

Abstract:

To investigate the early developmental characteristics and mitochondrial inheritance patterns of the hybrid offspring of a paternal Plectropomus leopardus and maternal Epinephelus fasciatus, the study systematically mapped the embryonic developmental trajectory and mitochondrial genome of the new germplasm. Results revealed that the fertilized hybrid eggs completed embryonic development within 28h55min, with the newly hatched larvae measuring 2.05 ± 0.37 mm in total length. The mitochondrial genome length of the hybrid was 16,570 bp, preserving 13 protein-coding genes (PCGs), two ribosomal RNA (rRNA) genes, and 22 transfer RNA (tRNA) genes. The hybrid's mitochondrial gene composition and arrangement showed high consistency with that of the maternal E. fasciatus. Concurrently, the co-linearity, Ka/Ks, and phylogenetic tree analyses collectively indicate that the hybrid progeny has a closer genetic relationship with the maternal parent, supporting the mitochondrial maternal inheritance of this species. This study details the embryonic development and mitochondrial inheritance of an intergeneric hybrid grouper germplasm, providing significant molecular biological evidence for grouper hybrid breeding, germplasm resource identification, and genetic diversity conservation.

Abstract: The fish liver, as the main detoxification organ, is highly susceptible to xenobiotic exposure, often resulting in various hepatopathies. The cytochrome P450 system plays a central role in xenobiotic metabolism, with cytochrome P450 reductase (CYPOR) supplying the electrons required for CYP enzyme activity. This study aimed to evaluate the relationship between the ecological state of a reservoir and fish health, including CYPOR levels, through hematological, bacteriological, and histological analyses. Samples of water and fish were collected from 12 littoral sites of Lake Ladoga. Forty fish from the carp (Cyprinidae) and perch (Percidae) families were examined. Hematological smears were stained with azure eosin; bacteriological cultures were grown on multiple media; liver samples were stained with hematoxylin and eosin and Sudan III. CYPOR levels in liver homogenates were measured by immunohistochemistry. Physical and hydrochemical analyses indicated a high pollution level in the littoral zones. Isolated bacterial species were non-pathogenic but exhibited broad antibiotic resistance. Hematological evaluation revealed erythrocyte vacuolization and anisocytosis. Histological analysis showed marked fatty degeneration in hepatocytes, indicating toxic damage. CYPOR concentrations ranged from 0.3–0.4 ng/ml in healthy fish to 5–6 ng/ml in exposed specimens, confirming environmental influence on enzyme activity. These findings support CYPOR as a sensitive biomarker of environmental stress and demonstrate differences between controlled and natural conditions in aquatic organisms.

Abstract: This study was carried out to investigate the perceptions of aquatic animal welfare (AAW) among educators (n = 47), students (n = 359), and aquaculture sector stakeholders (n = 34) in key aquaculture regions of South and South-Central Vietnam. Using a mixed-methods survey, we assessed perception scores, understanding of core welfare concepts, curricular coverage, and willingness to pay for welfare-friendly products. Although perception scores were high across surveyed groups, only 5.57% of students could identify most of the Five Freedoms of Animal Welfare, and 17.0% showed no understanding of welfare, highlighting a gap between awareness and understanding. No significant differences were found by academic major or year, indicating systemic curricular gaps. A small but significant negative correlation (Kendall–Theil Sen slope = –0.28, p < 1.25 × 10⁻¹²) suggests that greater curricular integration of AAW is associated with stronger welfare attitudes. Willingness to pay modest premiums (6–10%) for welfare-friendly products increased non-linearly with higher perception scores among educators and students, while aquaculture sector stakeholders appeared to prioritise economic factors over welfare. Although 88.2% of aquaculture sector stakeholder’s respondents supported curriculum reform and practical training opportunities, few (41.2%) identified formal competency standards for graduates. These results highlight the need for structured AAW curricula, community collaborative education models, and targeted interventions to close awareness understanding gaps. This study provides the first empirical insights into AAW perceptions among key education and aquaculture industry groups in Vietnam, offering a foun-dation for policy-driven curriculum reform to support ethical and sustainable aquaculture.

Abstract: An 8-week study was conducted to evaluate the effects of dietary marine protein hydrolysates as fish meal replacers in low-fish diets on the growth performance, feed utilization, and health status of Asian seabass (Lates calcarifer). The high fish meal (HFM) diet contained 25% fish meal, while the low fish meal (LFM) diet replaced 60% of the fish meal with soybean meal. Three experimental diets were formulated by supplementing the LFM diet with 5% tuna hydrolysate (TH), 2% shrimp hydrolysate (SH), and 5% salmon silage (SS), each replacing an equivalent amount of fish meal. These diets were designated as LFM+TH, LFM+SH, and LFM+SS, respectively. The results showed that the LFM+TH diet significantly improved percent weight gain, average daily growth, specific growth rate, protein efficiency ratio, and feed conversion ratio compared to the LFM diet (P< 0.05), without negatively affecting feed intake or metabolic markers. Histological analysis revealed improved villus length and goblet cell count in the intestine, indicating better nutrient absorption (P< 0.05). However, no significant differences were observed in hematological and immunological parameters, blood plasma metabolic markers, or carcass proximate composition (P>0.05). Furthermore, the LFM+TH diet exhibited superior survival rates under ammonia stress, highlighting its potential to enhance stress tolerance. These findings suggest that marine protein hydrolysates, particularly 5%TH, can serve as a sustainable and efficient alternative to fish meal protein in diets with up to 60% with soybean meal compensation, promoting better growth and survival in Asian seabass.

Abstract: Aquaculture is increasingly critical for meeting global protein needs, with fish consumption having doubled since the 1960s. However, alongside its rapid expansion, the industry faces the emerging challenge of microplastic (MP) contamination. Microplastics, derived from degraded plastic debris, aquaculture infrastructure, and contaminated feeds, are now widely detected in pond water, sediments, and farmed fish tissues. This narrative review critically examined evidence on the impacts of MPs in aquaculture, with a focus on fish health and disease susceptibility. Findings suggest that MPs disrupt immune responses, inducing oxidative stress and inflammatory signaling while impairing lymphoid function. MPs also alter the gut microbiome, promoting dysbiosis, reduced feed efficiency, and heightened mucosal inflammation. Moreover, MPs act as vectors for pathogens such as Vibrio sp., Aeromonas sp., and Tenacibaculum sp., creating a “plastisphere” that shelters microbes, concentrates toxins, and facilitates disease transmission. These biological and ecological effects collectively raise concerns for aquaculture sustainability, fish welfare, and food safety. While uncertainties remain regarding dose–response relationships under farm conditions, the convergence of evidence highlights MPs as an underappreciated threat to global fish health. Mitigation strategies will require integrated approaches addressing plastic waste management, feed safety, and aquaculture system design.

Abstract: Pacific sardine is a dynamic population that undergoes natural boom-and-bust cycles. Despite sardines’ ecological and economic importance, the variability that governs population changes remains poorly understood. Understanding the influence of oceanography on the life history, migration, and population dynamics of sardines is important for fishery management. Over the history of the California Current sardine fishery, numerous studies have attempted to explain why the US and Mexican portions of the sardine biomass off the West Coast should be divided into Northern (Cold - NSP) and Southern (Temperate - SSP) subpopulations. Since 2015, a habitat model including a Sea Surface Temperature (SST) threshold has been used to delineate subpopulations. The assessment and management of the NSP is conducted by the US (using an SST threshold of 16.7° C), while that of the SSP is conducted by Mexico (using a threshold of 17°C). Meantime, new population genetics and stock structure studies have found that the reproductive ecology of Pacific sardine reflects a single, panmictic population spread over a wide geographic range and influenced by environmental forcing, suggesting that assumptions regarding the two-subpopulation hypothesis be reconsidered, along with the influence of oceanography on sardine population dynamics. The implications of finding a single sardine population are significant, as this could result in a review of current US fishery management policies and reference points used to set the annual fishing quotas. In this paper we discuss the importance of the California Current’s influence on the population dynamics of sardine, current fishery management, and management implications.