Volume 77, Issue 4, 2025

Permanent URI for this collectionhttps://hdl.handle.net/10524/87910

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Effect of pH on Pacific abalone (Haliotis discus hannai) sperm quality
(2025) Pratiwi, Dian Y.; Kim, Tae M.; Oh, Young D.; Choi, Mi-Jin; Han, Kyu L.
In commercial abalone production, sperm quality is a key determinant of fertilization success and, consequently, the long-term sustainability of the industry. However, human activities, such as the release of acidic and alkaline industrial wastes, have altered ocean pH levels, particularly affecting coastal waters, which may reduce abalone sperm quality and prevent fertilization. Currently, most studies regarding the effects of pH have focused on the development of embryos and larvae. Research on Pacific abalone sperm quality responses to pH remains limited. This study investigates the impact of pH on the quality of Pacific abalone sperm and the success of fertilization. Fresh sperm were incubated for 15 min in artificial seawater at pH values ranging from 6 to 10. Sperm quality was then assessed using computer-assisted sperm analysis (CASA), which included measurements of motility, progressive motility, beat cross frequency (BCF), the amplitude of lateral displacement (ALH), curvilinear velocity (VCL), straight-line velocity (VSL), the straightness index (STR), linearity (LIN), and average path velocity (VAP). We also assessed fertilization rates, live/dead sperm viability, acrosome integrity, hydrogen peroxide levels, and DNA damage levels. Compared to the control, decreases in motility and progressive motility were observed at pH levels of 6, 9, and 10. However, other CASA metrics (BCF, ALH, VCL, VSL, STR, LIN, and VAP) were not significantly affected. The percentage of cells exhibiting DNA damage was impacted considerably by pH. Similarly, the proportion of cells with damaged acrosomes rose at pH 10, and the proportion of dead sperm cells increased dramatically at pH 6, 9, and 10. At pH 6, hydrogen peroxide levels increased. Fertilization rates were reduced by exposure to the extreme pH levels tested, pH 6 and pH 10. In conclusion, Pacific abalone sperm quality may be adversely affected in seawater at pH values of 6, 9, and 10. These findings suggest that changes in coastal seawater pH may impact sperm quality, potentially affecting both natural abalone populations and aquaculture yields.
A parentage identification system and genetic analysis of growth traits in Percocypris pingi (Tchang, 1930) for breeding programs
(2025) Zhu, Siyi; Dai, Yun; Deng, Longjun; Li, Tiancai; Li, Tong; Wang, Qingjie; Zhong, Shun; Ying, Xing; Dai, Fulin; Wang, Dongjie; Luo, Wei; Du, Zongjun
To effectively evaluate genetic diversity and estimate trait heritability, the establishment of a robust parentage identification system is indispensable. For tetraploid species, the success of such a system critically depends on the development of highly polymorphic loci. In this study, we screened simple sequence repeats (SSRs) for Percocypris pingi, a tetraploid species, by leveraging full-length data. Using SSREnricher software, we further compared these sequences with muscle transcriptome data obtained from four geographically distinct populations to identify highly polymorphic SSR loci. We identified nine highly polymorphic SSR markers with a mean polymorphism information content (PIC) of 0.647 and constructed a high-resolution parentage assignment system with a cumulative exclusion probability of 0.999984. The system was validated using 300 offspring from single-pair families, achieving an assignment accuracy of 96%. Growth traits, including total length (TL), body length (BL), and body weight (BW), were measured in 270 individuals from mixed-rearing groups. We investigated the relationship between parental genetic distance and offspring growth. The average Bruvo distance between parents was relatively low (0.37). A weak positive trend was observed between parental genetic distance and offspring TL (P > 0.05). Given that all pairwise trait correlations exceeded 0.9 (P < 0.05), the multivariate model provided more reliable estimates, and BW (heritability = 0.307) emerged as a priority trait for future breeding programs. Overall, our findings highlight the utility of transcriptome-derived SSR markers for accurate parentage analysis and emphasize the importance of monitoring genetic diversity and estimating trait heritability in stock enhancement efforts.
Screening of microsatellite loci and analysis of polymorphism in Triplophysa hsutschouensis based on RAD sequencing
(2025) Liu, Ya; Lin, Hangyu; Ke, Hongyu; Zhao, Han; Zhao, Zhongmeng; Su, Shengqi; Lin, Jue; Li, Qiang
To assess the genetic diversity of Triplophysa hsutschouensis population in the Shule River basin, we employed restriction site-associated DNA sequencing (RAD-Seq) to sequence T. hsutschouensis genome. Using this technology, we identified suitable microsatellite (SSR) markers specific to T. hsutschouensis population and synthesized 67 primer pairs, of which 18 were found to be polymorphic. Our analysis of 46 T. hsutschouensis individuals revealed that the number of alleles (Na) ranged from 2 to 16, with the effective number of alleles (Ne) varying between 1.293 and 8.672. Observed heterozygosity (Ho) ranged from 0.261 to 0.957, expected heterozygosity (He) from 0.227 to 0.885, and polymorphism information content (PIC) from 0.201 to 0.874. The average values obtained were Na = 7.056, Ne = 3.540, Ho = 0.609, He = 0.639, and PIC = 0.595. Hardy-Weinberg equilibrium testing showed that five of the 18 polymorphic SSR loci deviated significantly from expectations after Bonferroni correction, while the remaining 13 loci conformed to expectations, indicating no significant genetic disturbances in the population. These newly identified polymorphic SSR markers will be valuable for future genetic diversity analysis and conservation efforts regarding T. hsutschouensis populations.
Isolation, identification, and pathogenicity analysis of Staphylococcus epidermidis in Chinese soft-shelled turtles
(2025) Zhang, Chunjie; Liu, Wei; Meng, Yan; Xue, Mingyang; Jiang, Nan; Zhou, Tong; Xiao, Zidong; Song, Hongyang; Chen, Mengmeng; Liu, Xiaodan; Zhou, Yong
In this study, a dominant bacterial strain was isolated from diseased Chinese soft-shelled turtles (CSSTs) (Pelodiscus sinensis) reared at an aquaculture farm in Hubei Province. Its pathogenic characteristics and virulence were investigated. Based on morphological observation, 16S rRNA gene sequence analysis, and physiological and biochemical characterization, the isolate was identified as Staphylococcus epidermidis. This isolate harbored virulence genes associated with adhesion and biofilm formation, including icaA (intercellular adhesion gene A), bhp (biofilm-associated hydrophobin-like protein) and clfA (clumping factor A), and exhibited a median lethal dose (LD50) of 8.99×10³ CFU/g weight in CSSTs. Additionally, antibiotic susceptibility testing revealed that the strain was sensitive to gentamicin, doxycycline, florfenicol, neomycin, enrofloxacin, and cefotaxime. Infected CSSTs displayed varying degrees of pathological changes in the intestine, kidneys, spleen, and liver. Moreover, the expression levels of immune-related genes MAP2K6, MyD88, and TLR8 were significantly upregulated in internal organs. Overall, these results indicate that infection with S. epidermidis can lead to significant mortality in CSSTs. This study provides scientific reference for the detection and control of S. epidermidis infections in CSSTs.
Otolith Morphology Reveals Population Connectivity of Siniperca kneri (Garman, 1912) in the Xijiang River
(2025) Cui, Weijie; He, Zhongtang; Zhang, Fengling; Xu, Li; Zhou, Yang; Su, Shengqi; He, Tao
Morphological and morphometric analyses of otoliths are widely used for intraspecific comparisons and fish stock identification. This study examines the stock structure of Siniperca kneri (Garman, 1912), an endemic and economically important carnivorous fish in China, using otolith shape analysis in the Xijiang River. Specimens were collected from three sites in the middle and upper reaches of the river. Traditional shape indices and elliptic Fourier descriptors were used to evaluate otolith morphology after statistically removing the effect of fish size (allometry). After applying corrections for multiple comparisons, no significant differences were found in any of the eight shape indices among groups. Canonical analysis of principal coordinates (CAP) based on elliptic Fourier coefficients also revealed no clear morphological differentiation among the sites. The initial discriminant analysis yielded a raw classification success rate of 61.1%, but a more robust leave-one-out cross-validation reduced the accuracy to 55.6%, indicating substantial morphological overlap. These results suggest that S. kneri in the study area likely constitutes a single phenotypic stock with limited spatial structuring. The absence of strong stock differentiation may be attributed to relatively homogeneous environmental conditions and the potential effectiveness of fish passage facilities that could maintain ecological connectivity. However, these conclusions are tempered by the study's limitations in sample size. These findings underscore the importance of preserving river connectivity and highlight the urgent need for further studies utilizing otolith microchemistry and genetic tools to validate these findings and support effective conservation management.
Analysis of the main influencing factors of sustainable devel-opment of recreational fishery in Zhejiang Province based on questionnaire survey
(2025) Li, Jiao-Long; Qian, Wei-Guo
Recreational fisheries play a vital role in promoting sustainable coastal development, yet empirical research to inform policymaking remains limited. This study investigates the factors influencing the sustainable development of recreational fisheries in Xiangshan County, Zhejiang Province, using principal component analysis of questionnaire survey data. The analysis identifies five key dimensions: resources, infrastructure, service quality, fishery culture, and recreational fishery activities. Results indicate that infrastructure and the natural environment exert the strongest influence on sustainability outcomes. Based on these findings, policy recommendations are proposed to enhance both ecological and economic value. First, government planning should prioritize infrastructure improvements to enhance tourists’ convenience and comfort. Second, cultural aspects of fishing should be further developed through local activities that enrich cultural heritage and improve the attractiveness of recreational fisheries. Third, production safety must remain a fundamental priority to ensure long-term industry stability. Overall, the study emphasizes the need to create distinctive recreational fishery products, improve service quality, strengthen ecological protection, and advance resource management. The proposed “environment + industry + culture” framework offers a practical evaluation tool for policymakers and stakeholders. By integrating ecological, cultural, and economic considerations, recreational fisheries in Xiangshan County can achieve green and sustainable development while meeting the evolving needs of tourists.
Malathion and copper sulfate exposure effects on humoral and cellular components of Pacific white shrimp Litopenaeus vannamei
(2025) Hernández-Mendoza, E.G.; Aguilar-Juárez, M.; Valdez-González, F.J.; Frías-Espericueta, M.G.; González-Hermoso, J.P.; Bautista-Covarrubias, J.C.
Humoral and cellular responses were evaluated in juvenile Litopenaeus vannamei shrimp following 96-hour (h) exposure to malathion; copper sulfate was used separately. Four concentrations lower than median lethal concentration (LC50-96 h) were applied (1, 10, 20, and 50% of LC50-96 h). Clotting time (CT), hemocyanin concentration (HC), glucose (G), phenoloxidase activity (PO), total hemocyte count (THC), and differential hemocyte count (DHC) were recorded at different times (0, 48, and 96 h); CT was higher in shrimp exposed to copper sulfate, evidently the presence of both substances tested caused a reduction in HC concentration at 48 h and increased at 96-h exposure. The average G level of the exposed shrimp was lower than the average G values of control shrimp. Increase in PO activity was determined in shrimp after 48-h exposure to both chemicals. Malathion caused a greater increase in mean THC values than those of shrimp exposed to copper sulfate. A decrease in hyaline hemocytes and increase in semi-granular and granular hemocytes were evident in shrimp exposed to both chemical concentrations. Finally, the variables analyzed were affected at concentrations below LC50-96 h of both chemicals tested. Evidently, malathion and copper sulfate at relatively low concentrations could affect shrimp physiology affecting their disease susceptibility.
Analysis of the correlation between phenotypic color differences and molecular regulation of Amphiprion percula and A. ocellaris
(2025) Hu, Jing; Wang, Mengya; Wang, Bo; Ma, Zhenhua
This study investigates phenotypic characterization with molecular analysis to elucidate the mechanisms underlying skin color divergence between Amphiprion percula and A. ocellaris. These two closely related clownfish species differ markedly in skin pigmentation and are compared here to understand how ecological adaptation and genetic divergence shape phenotypic traits. HSB（Hue, Saturation, Brightness）colorimetry revealed significant interspecific differences (A. ocellaris: L=-57.11±2.59, a=29.91±4.77, b=20.70±4.68; A. percula: L=-59.87±4.30, a=14.08±3.42, b=13.32±5.03), with A. ocellaris exhibiting brighter reddish-yellow tones (ΔE=67.85), contrasting with A. percula's darker greenish-blue hues (ΔE=63.26). The pigment content analysis showed that A. percula had higher melanin content (90 mg/g vs 60 mg/g, p <0.05) while A. ocellaris showed elevated carotenoids (30 μg/g vs <10 μg/g, p <0.05). Histological analysis identified distinct melanocyte architectures—A. percula displayed tightly packed, irregular melanocytes in band-like arrangements, whereas A. ocellaris had sparsely distributed uniform cells with punctate patterning. Transcriptomic analysis identified 1925 differentially expressed genes (641 upregulated, 1,284 downregulated), based on thresholds of |log₂ fold change| ≥ 1 and false discovery rate (FDR) < 0.05, with enrichment in pigment biosynthesis pathways including cytochrome P450-mediated metabolism. Critical regulatory genes (MC1R, tyrosinase, CYPs) exhibited species-specific expression patterns. Melanogenic genes (tyrosinase) were upregulated in A. percula (1.5-fold, p <0.01), correlating with melanocyte proliferation and dark skin, whereas carotenoid-associated CYPs were overexpressed in A. ocellaris (2.3-fold, p <0.01), driving its vibrant coloration. This research highlights the genetic and cellular mechanisms underlying color variation in clownfish and provides valuable insight for ornamental fish breeding and genetic improvement.
Dietary Medium-Chain Triglycerides (MCTs) enhanced growth performance of nursery-reared milkfish Chanos chanos (Forsskål, 1775)
(2025) Batilong, Ludevito; Traifalgar, Rex F.M.; Ranara, Cyril T.B.; Tanay, Dennis D.; Del Castillo, Carmelo S.; Lumayno, Sanny D.
Lipid quality plays a pivotal role in early milkfish nutrition, yet the potential of medium‑chain triglycerides (MCTs) as productivity‑enhancing lipid sources remains insufficiently characterized in milkfish aquaculture. The study evaluated the effects of dietary MCTs on growth performance, feed efficiency, nutrient retention, and carcass composition of juvenile Chanos chanos. An 8‑week feeding trial was conducted using diets supplemented with 0%, 3%, 4%, and 5% MCTs in a flow‑through seawater system. Growth parameters, feed conversion efficiency (FCE), protein efficiency ratio (PER), survival, carcass composition, and nutrient retention were assessed at the end of the trial. MCT supplementation significantly influenced fish performance. The highest weight gain (1217.7%) and specific growth rate (4.1) were observed in the 5% MCT group, while 3% and 4% inclusion improved protein retention (8.95%, 6.79%) and carcass crude protein content (84.45%, 83.60%). FCE and PER were also enhanced at 4-5% inclusion. However, excessive supplementation (5%) led to elevated lipid retention (43.35%) and body fat deposition, accompanied by reduced protein retention (2.77%). Survival (61-70%) did not differ significantly among treatments, indicating good tolerance. Overall, the results of this study indicate that dietary MCTs can be incorporated as functional lipid sources in milkfish diets, with a 4% inclusion level providing improvements in growth, feed efficiency, and protein utilization while limiting excessive fat deposition, thereby supporting enhanced juvenile milkfish production.
Characteristics of bacteria strain Streptococcus iniae SiTH1 causing pop-eye disease in Asian seabass (Lates calcarifer) in Vietnam: a candidate for inactivated vaccine production.
(2025) Nguyen, Thuy T.T.; Nguyen, Chi T.Q.; Le, Tuan H.; Nguyen, Hung V.; Ronneseth, Anita; Wergeland, Heidrun I.
Bacterial strain Streptococcus iniae SiTH1 was isolated from Asian seabass cage-cultured in Vietnam with clinical signs such as pop-eye, hemorrhage, and skin ulcers. The strain SiTH1 was identified as S. iniae by PCR analysis, using the two specific primer pairs SP1/SP2 and LOXF/LOXR, which target the ITS rDNA and lctO, respectively. Six virulence genes were identified in S. iniae SiTH1, including simA, scpI, pdi, pgm, cpsD, and sagA. High mortality was obtained following experimental challenge of Asian seabass with S. iniae SiTH1, with the 50% lethal dose (LD50) being 104.4 CFU/fish. For evaluating immune responses, fish were immunized by i.p. injection (0.1 mL/fish) with inactivated bacteria by formalin at three concentrations: 109, 1010, and 1011 CFU/mL. Expression analysis of five immune-related genes (IL-1β, IL-6, IL-10, Mx, and TNF-α) following injection revealed that at 24 hours after immunization, all five genes were regulated at different levels, related to the antigen concentration. Specifically, bacterial concentrations of 109 and 1010 CFU/mL tended to stimulate immune-related genes more compared to a higher concentration of 1011 CFU/mL. Serum antibody titers in fish tended to increase gradually with antigen concentration. The effect of vaccination, tested by challenge of fish with live bacteria, showed that 21 days after immunization, the RPS of fish vaccinated with antigen concentrations of 109, 1010, 1011 CFU/mL were 63.3%; 76.7%; 78.3%, respectively. Based on these results, the S. iniae SiTH1 strain is a good candidate for inactivated vaccine production against streptococcosis in seasbass in Vietnam.
Research on the changes in fish composition in the Chongqing section of the Fujiang River based on eDNA technology
(2025) Ma, Qianqian; Dan, Yan; Zhang, Chuang; Xie, Yong; Li, Yan
To accurately assess riverine fish diversity, which is crucial for aquatic ecosystem conservation, this study utilized environmental DNA (eDNA) metabarcoding as a non-invasive and efficient alternative to traditional survey methods that have limitations, such as being damaging and inefficient. We collected water samples from 14 sites in the Chongqing section of the Fujiang River during the fish spawning (June), feeding (August), and wintering (November) periods of 2023, analyzed fish community composition through high-throughput sequencing of the 12S rRNA and COI genes and compared these results with data from traditional net fishing. The eDNA technique detected 72, 53, and 63 fish species in the three respective periods, which were significantly higher than the number of species captured by traditional fishing methods (40 in August and 37 in October). The results showed that the Cyprinidae family was the dominant family in terms of species number across all seasons, accounting for 65.08% to 71.70% of the detected species. Importantly, eDNA successfully detected nationally protected species such as Leptobotia elongata and Procyris rabaudi, as well as multiple endemic and invasive species, with overall species richness peaking during the June spawning period. This study confirms that eDNA metabarcoding offers higher sensitivity and comprehensiveness for monitoring riverine fish diversity, especially for rare and endangered species, and provides critical scientific data on seasonal community dynamics for the conservation and management of the Fujiang River basin.
Structural characterization and sex-differential expression analysis of the SOCS1 gene in Pelodiscus sinensis
(2025) Zhu, Yulei; Li, Tao; Li, Xifan; Zheng, Xiaokai; Wang, Jingwen; Zeng, Dan
To investigate the evolutionary and functional characteristics of the SOCS1 gene in reptiles, we isolated and characterized this gene from the Chinese soft-shelled turtle, Pelodiscus sinensis. The full-length cDNA of P. sinensis SOCS1 (2,782 bp) was cloned and encoded a 207-amino acid polypeptide containing typical SH2 (73-156aa) and SOCS box (167-203aa) domains. The evolutionary analysis showed that SOCS1 exhibited high homology (>95%) with other turtle species and SH2 and SOCS box domains were highly conserved in vertebrates. Protein-protein interaction (PPI) network predictions suggested that SOCS1 might interact strongly with members of the JAK kinase family, the ubiquitin ligase complex, and the insulin receptor. Further expression analysis in different tissues revealed that the expression level of SOCS1 was significantly higher in female gonads and intestines than that in males (P < 0.05). Meanwhile, hormone treatment experiments indicated that the SOCS1 in female gonads was specifically responsive to estradiol (E2) treatment and peaked at 12 h after hormone treatment (P < 0.05). Collectively, our study reveals the molecular features of P. sinensis SOCS1 and its potential role in sex-related physiology, laying a foundation for further investigation into the regulatory mechanisms of growth, immunity, and reproduction in turtles.
Study on the agglomeration level and formation mechanism of aquaculture industry in China
(2025) Wang, Jing; Sun, Chen; Jin, Hongtao; Xu, Shiwei; Che, Bin; Zhang, Haiqing
Industrial agglomeration plays an increasingly critical role in optimizing the efficiency of resource allocation, promoting local and national economic growth and enhancing international competitiveness. This study constructs a theoretical model of the formation mechanism of aquaculture industry agglomeration and uses location entropy and Geodetector methods to explore the agglomeration level and formation mechanism of China's aquaculture industry. The conclusions of the study are as follows: (1) There is an industrial agglomeration phenomenon in China's aquaculture industry, but the degree of industrial agglomeration is not high, and the agglomeration phenomenon shows a weakening trend as a whole. At the same time, the agglomeration level of the aquaculture industry varies greatly among regions; (2) Aquaculture industry agglomeration is the result of the interaction of comparative advantage, external economic and institutional policy environment. The impact of various factors on the agglomeration of the aquaculture industry will change over time; (3) Industrial correlation and production technology level are important influencing factors of aquaculture industry agglomeration, with the highest explanatory power of 82.3 % and 66.9 %, respectively.
Expression analysis of the insulin-like peptides genes (ILPs) in the redclaw crayfish Cherax quadricarinatus and new insights into sexual development
(2025) Xu, Yi; Zheng, Jianbo; Jiang, Wenping; Chi, Meili; Cheng, Shun; Liu, Shili; Li, Fei; Zhu, Chao; Zhang, Haiqi
Insulin-like peptides (ILPs) are involved in various physiological processes in metazoans, including metabolism, growth, and reproduction. However, their presence and function in decapods are largely unexplored. To investigate the role of ILPs in the redclaw crayfish, this study characterized two ILP genes (Cq-ILP1 and Cq-ILP2) and analyzed their genomic structure and protein domains. Multiple sequence alignments revealed highly conserved structural features across ILPs from different species. Tissue expression analysis indicated that Cq-ILP1 was exclusively expressed in the ovary, suggesting its involvement in female reproduction. In early juvenile stages, Cq-ILP1 expression was first detected in female individuals at 2 cm body length (BL2), coinciding with the appearance of genital pores. Additionally, Cq-ILP1 expression progressively increased during ovarian development stages from I to V, then decreased to its lowest level at the end of stage VI. These findings suggested that Cq-ILP1 played a pivotal role in sexual development. Moreover, injection of Cq-ILP1–dsRNA resulted in a significant reduction in vg expression. These results provided new insights into the function of non-IAG ILP genes and offered valuable resources for future research on ovarian development in crustaceans.
Effects of different concentrations of sodium humate on the growth, enzyme activity and water microflora of Pacific white shrimp (Litopenaeus vannamei) based on the zero-water exchange model
(2025) Xie, Shaolong; Liao, Wuquan; Cui, Yuhang; Lin, Zexu; Wang, Ping; Sun, Chengbo
In the present study, the effect of sodium humate on growth performance, enzyme activity, and water column microflora of Litopenaeus vannamei was investigated using a zero-water exchange culture model. Different concentrations of sodium humate were added to the culture water during the 54-day experimental period. The results showed that the growth indexes such as shrimp specific growth rate and survival rate were significantly better in the 3 mg/L addition group (sodium humate) than in the control group (p<0.05); and the 12 mg/L addition group had the most significant effect in reducing the levels of ammonia nitrogen and nitrite nitrogen in the water column (p<0.05). In terms of enzyme activities, lipase, trypsin, superoxide dismutase, and lysozyme activities were the highest in the 9 mg/L addition group (p<0.05), while catalase and phenol oxidase activities were the greatest in the 6 mg/L and 12 mg/L addition groups (p<0.05). Microbiological analyses showed that the control group had the least heterotrophic bacteria, but Vibrio counts were significantly higher than those of the additive group (p<0.05). The bacterial diversity was higher in the additive group than in the control group (p<0.05) and had different dominant flora at the genus level. The experimental results show that sodium humate can improve the water quality and substrate environment, enhance the antioxidant capacity of shrimp, and promote their growth and survival. It can effectively reduce the concentration of ammonia nitrogen and nitrite nitrogen in the water body, inhibit the growth of Vibrio, and optimize the diversity and structure of the water body microecology. In conclusion, the addition of sodium humate to shrimp aquaculture water can significantly enhance the growth performance of shrimp, improve the microecology of the water body, and provide a theoretical basis and practical guidance for eco-friendly shrimp aquaculture.
Environmental risks of microplastics: A Review of their distribution and effects on aquatic ecosystems
(2025) Zuo, Yan; Ma, Longfei; Liu, Zipu; Li, Sheng; Zhang, Zichao; Yu, Jia
Microplastics, as globally emerging pollutants, threaten aquatic ecosystems through dual mechanisms: (1) exerting direct physicochemical stress on organisms, and (2) interacting synergistically with co-existing pollutants, ultimately disrupting food web integrity and jeopardizing both ecological security and human health. However, research on the ecological risks of microplastics faces important gaps: first, experimental conditions differ significantly from real environmental conditions, making it difficult to accurately simulate chronic low-dose exposure scenarios; second, cross-scale risk assessments from the molecular to the ecosystem level are lacking. This severely hinders the accurate understanding and effective management of microplastic risks in aquaculture systems. Based on this, this study systematically integrates the cross-scale mechanisms of microplastic impacts on aquatic organisms, focusing on their environmental distribution, biological exposure pathways, and bioaccumulation characteristics to elucidate their toxic effects and ecological risks. The study reveals the "individual-community-system" cascade effect of microplastics on aquatic ecosystems, and then proposes standardized suggestions for risk assessment of microplastics in aquaculture, providing a theoretical basis and practical guidance for risk control of microplastics in both natural and aquaculture systems.
Fish diversity assessment in the Yuanshui River during the ten-year fishing ban using environmental DNA metabarcoding
(2025) Liu, Liangguo; Zhang, Tangsi; Luo, Congqiang; Xie, Xiao; Luo, Yushuang; Song, Bolan; Wang, Jinlong
To understand the status of fish diversity in the middle reaches of the Yangtze River's Yuanshui River basin during the ten-year fishing ban, this study employed environmental DNA (eDNA) metabarcoding technology. Fish resources were surveyed and diversity analyzed across 38 sampling points within seven river sections of the Yuanshui River basin in September 2023. The results were compared with data obtained using conventional fishing gear methods from four identical sections (Changde, Yuanling, Chenxi, Hongjiang) to explore the application of eDNA technology for fish resource monitoring in the Yangtze River basin and to investigate the similarities and differences in monitoring outcomes between the two methods. The eDNA metabarcoding approach identified a total of 94 fish species, belonging to 10 orders, 17 families, and 57 genera. Cypriniformes was the most abundant order (65 species, 69.15%), and Cyprinidae dominated (54 species, 57.45%) within families. Among the 94 species, 12 were endemic to the Yangtze River basin, 11were key protected wildlife species in Hunan Province, and 3 were non-native species. The predominant ecological traits of the fish assemblage were characterized by lentic-resident habits (56.38%), omnivorous feeding (63.83%), and demersal habitat utilization (45.74%). Diadromous migrants, herbivorous feeders, and lower water column species were relatively scarce. A comparative study in four identical sections of the Yuanshui River utilized environmental DNA (eDNA) metabarcoding and conventional fishing gear to assess fish diversity. Across all sections, eDNA detected a total of 89 fish species while conventional methods detected 93 species, with 62 species co-detected by both approaches. Site-specific comparisons revealed that within the Changde section, eDNA identified 70 species compared to 55 species captured by conventional gear, resulting in 40 shared species. In the Yuanling section, eDNA detected 71 species against 53 species from conventional sampling, yielding 35 co-detected species. The Chenxi section showed eDNA detection of 44 species and conventional gear detection of 38 species, with 20 species found by both methods. Similarly, in the Hongjiang section, eDNA recorded 49 species and conventional methods 47 species, also sharing 20 species. Both the total number of fish species and the number of shared species detected in the Changde and Yuanling sections were significantly higher than those in the Chenxi and Hongjiang sections. Within the same river section, the Shannon diversity index and Pielou evenness index calculated based on the conventional fishing gear data were consistently greater than those derived from the eDNA analysis. This study demonstrates the high credibility of environmental DNA (eDNA) technology for monitoring fish stocks within the Yangtze River Basin. Combining eDNA methods with conventional fishing gear surveys provides a more comprehensive assessment of fish diversity throughout the basin. These findings offer valuable references for evaluating the effectiveness of fishing bans, protecting fish resources, and informing fisheries management strategies in the Yuanshui River and broader Yangtze Basin.
Dissolved oxygen tolerance of Hippocampus abdominalis across varying temperature regimes
(2025) Zhao, Chunnuan; Li, Junjie; Xu, Shuai; Wu, Yuping; Xie, Chaoyi; Han, Haiying; Ren, Liqun; Li, Bo; Zheng, Yanxin; Chen, Yang; Fan, Nini; Yu, Tao
To understand the dissolved oxygen tolerance of Hippocampus abdominalis during transportation or cultivation at different water temperatures, this study investigated the patterns of oxygen consumption and activity changes in H. abdominalis (with body lengths of 11.55-12.05 cm and weights of 4.60-6.19 g) as the dissolved oxygen (DO) levels in the water decreased. The experiment utilized the static water respiration chamber method, using a water bath to control the temperature with a variation not exceeding 1℃. Three experimental temperature gradients were designed: 14℃, 19℃, and 24℃, with three repetitions for each group and a blank control group set for comparison. Results showed‌: suffocation point (±SD) were (0.18±0.03) mg/L at 14°C, (0.20±0.05) mg/L at 19°C, and (0.21±0.02) mg/L at 24°C. Elevated temperatures reduced DO saturation levels and increased the suffocation point. During the asphyxiation phase (Phase I: onset to first death), oxygen consumption rates (OCR) were 0.29 mg/(g·h), 0.46 mg/(g·h), and 0.51 mg/(g·h), respectively at three temperatures. During the mortality phase (Phase II: first death to 100% mortality), OCR were 0.02 mg/(g·h), 0.01 mg/(g·h), and 0.01 mg/(g·h). Under salinity 28.25 and pH 8.54, both DO parameters and suffocation point exhibited temperature dependency. Phase I OCR increased with temperature, with 14°C group significantly lower than 19°C/24°C groups. Phase II OCR at 14°C was slightly higher than in other groups. All groups showed a significant OCR decline with DO reduction. H. abdominalis employed a ‌conformist respiratory strategy, modulating oxygen consumption to adapt to hypoxia. Metabolic rates rapidly escalated during asphyxiation but minimized under critical hypoxia with narrow DO variation margins. The study demonstrates‌an immediate high-oxygen-consumption response under DO stress. Poor hypoxia tolerance with stringent DO requirements. Dissolved oxygen is closely related to fish metabolism and energy consumption. The large-scale breeding of juvenile seahorses requires stringent conditions, where high-quality germplasm supply is a prerequisite for successful breeding, and the survival rate during transportation ensures the stable supply of germplasm. Real-time monitoring of DO levels, combined with behavioral observations, is essential for standardizing protocols in aquaculture and transport operations. This study provides theoretical support for oxygen management during transportation by quantitatively analyzing the oxygen consumption rate.
Adaptation of the Chinese cyclina (Cyclina sinensis) to unconventional uubstrate materials: Insights from growth performance, antioxidant capacity, and aquaculture water quality monitoring
(2025) Li, Zhengyi; He, Guojun; Chen, Yihua; Yan, Shiyu; Wang, Chaohua; Du, Shizhao; Dong, Zhiguo; Li, Xiaoying
Although bivalve factory farming is a promising aquaculture model, traditional mud and sand substrates are problematic due to their difficulty in cleaning and their potential to degrade water quality over time. The goal of this study was to evaluate the practicality of three new materials (quartz sand, glass balls, and shell powder) as substrates for long-term farming of the Chinese cyclina (Cyclina sinensis) by assessing changes in water quality and physiological and biochemical indicators of the clams. The concentrations of total phosphorous, total nitrogen, nitrite nitrogen, and ammonium nitrogen in the culture water of the shell powder substrate were significantly lower than those of the silt (control), glass ball, and quartz sand groups (P < 0.05). The survival rate of clams in the shell powder group was the lowest（P < 0.05). No significant difference in survival was detected among the silt, glass ball, or quartz sand groups (P > 0.05). The body weight of the shell powder group reached 3.63 ± 0.15 g and was significantly higher than those of the other groups (P < 0.05). The total antioxidant capacity of the shell powder group
The positive effects of dietary Rhodiola rosea extract on liver glucose metabolism and antioxidant/inflammatory response in Lateolabrax maculatus fed high-carbohydrate diets
(2025) Zheng, Luzhe; Wang, Zhanzhan; Zhang, Bo; Zhao, Chao; Wang, Jun; Wang, Yun; Lin, Heizhao; Ma, Zhenhua; Qiu, Lihua; Zhou, Chuanpeng
This study investigated the effects of Rhodiola rosea extract supplementation on liver morphology, antioxidant capacity, inflammatory response, insulin signaling pathway, and glucose metabolism in Lateolabrax maculatus (9.37±0.14g). Three experimental diets were prepared: a control group (20% carbohydrate), a high-carbohydrate (HC) group (30% carbohydrate), and a high-carbohydrate with Rhodiola rosea extract (HCR) group (30% carbohydrate + 120 mg/kg Rhodiola rosea extract). The HC group showed significant increases in survival rate (SR), hepatosomatic index (HSI), triglyceride (TG), and liver malondialdehyde (MDA) levels, along with increased liver vacuoles, blurred cell boundaries, and larger lipid droplets. Additionally, the expression levels of Keap1, NF-κB, IKKβ, TNF-α, IL-8, IL-12p40, AKT2, SOCS3, GK, PEPCK, FBP, and GSK3β mRNA in hepatic tissue were markedly higher than in the control group (p < 0.05). Conversely, liver activities of T-AOC and CAT, and mRNA levels of CAT, HO-1, Nrf2, and TGF-β were significantly lower (p < 0.05). Compared to the HC group, the HCR group exhibited significant increases in SGR, plasma indices of INS, LA, PA, and liver enzyme activities of T-AOC and SOD (p < 0.05), as well as elevated mRNA levels of CAT, TGF-β, PI3Kα, PI3Kβ, GK, PK, and PFK in the liver (p < 0.05). Histological analysis revealed that hepatocytes in the HCR group had a higher concentration of nuclei, and the size and quantity of lipid droplets were reduced compared to the HC group. Furthermore, liver glycogen, plasma indices of TG and ALT, and liver enzyme activities of PEPCK, HK, and CAT decreased in the HCR group (p < 0.05). The expression levels of Keap1, IKKβ, IL-8, IL-12p40, NF-κB, IFN-γ2, SOCS3, TNF-α, FBP, G6Pase, and GSK3β mRNA were also reduced in the HCR group compared to the HC group (p < 0.05). In conclusion, Rhodiola rosea extract supplementation at 120 mg/kg in high-carbohydrate diets can mitigate the adverse effects of carbohydrate-rich diets on Lateolabrax maculatus by improving glucose metabolism and enhancing defenses against oxidative stress and inflammation.

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