The Jiupan River, a tributary of the Three Gorges Reservoir in the upper Yangtze River, plays a crucial role in regional aquatic biodiversity conservation due to its preserved natural hydrological regime and ecological heterogeneity. A total of 45 fish species were recorded in this study, dominated by Cyprinidae, and characterized by bottom-dwelling, rheophilic, and omnivorous traits. Three dominant species—Schizothorax prenanti, Discogobio yunnanensis, and Aristichthys nobilis—accounted for over 60

Cascade-dam systems impose repeated hydrological discontinuities that convert a river continuum into alternating reservoir–river segments, enhancing environmental heterogeneity and longitudinal gradients beyond the influence of a single dam. Seasonal shifts in temperature and hydrologic conditions also modulate connectivity along the cascade, yet how these drivers jointly shape bacterial community assembly remains poorly understood. This study investigated 10 cascade-dammed reaches of the Qijiang River, collecting paired sediment and water samples in summer and winter. Using an integrated approach of 16S rRNA gene amplicon sequencing, functional gene quantification, and potential process assays, we analyzed the impacts of spatial fragmentation and seasonality on bacterial community structure, assembly mechanisms, and carbon-nitrogen functions. The results revealed a habitat partitioning phenomenon characterized by two divergent assembly mechanisms. The sediment community, predominantly shaped by stable spatial gradients, followed a deterministic track where assembly was consistently dominated by selection. Conversely, the highly sensitive water community followed a season-responsive track, with its assembly shifting from mixed assembly with elevated stochasticity in summer to deterministic control in winter. This functional partitioning was also evident: sediment functions were more strongly associated with community structure, while the water community exhibited high functional redundancy, maintaining relatively stable functional potential despite marked seasonal compositional shifts. Together, these results provide a mechanistic explanation for why dam cascades matter by demonstrating that repeated, season-modulated fragmentation generates habitat-specific assembly pathways and may buffer functional stability in regulated river landscapes.

Cascade dams fragment river habitats, but how seasonal hydrology modulates the biogeography and assembly of fish gut microbiota remains unclear. We surveyed gut bacterial communities of the omnivorous fish Saurogobio punctatus across 10 reaches separated by cascade dams in the Qijiang River during the wet (summer) and dry (winter) seasons using 16S rRNA gene amplicon sequencing. Sampling was synchronized among reaches to minimize temporal variability. Winter exhibited stronger differentiation among reaches and a steeper distance-decay pattern, and reach-scale environmental heterogeneity (especially dissolved inorganic nitrogen) was more stable under weak hydrodynamics. Null model analyses showed that stochastic processes dominated in summer, with dispersal-related processes and drift being prominent under high connectivity, whereas deterministic assembly increased in winter and was mainly associated with homogeneous selection. Compositionality-aware differential abundance analysis (ANCOM-BC2) identified 409 genera with a significant seasonal differential abundance after adjusting for reach (FDR q < 0.05). Random forest classification, used as a complementary prediction-oriented feature-ranking analysis, indicated higher reach discriminability in winter, with Nitrospirota ranking among the top features. PLS-PM indicated that α-diversity had the strongest direct association with β-diversity in the specified model, whereas spatial and environmental effects were linked to β-diversity mainly through indirect, α-diversity-mediated pathways. Biologically, α-diversity may reflect an integrative summary of the within-gut taxon pool shaped by host filtering and environmentally derived inputs (e.g., diet- and habitat-associated sources), which can influence the magnitude of between-reach compositional turnover. Together, these results show that seasonal hydrological regimes tune spatial turnover and assembly of fish gut microbiota in cascade-regulated rivers.

This study used environmental DNA (eDNA) metabarcoding to monitor fish communities at 14 sites along the upper Yangtze River across four seasons, aiming to understand seasonal variations in community structure. This study reflects on the current status of fish community structure in the region by leveraging an analytical discussion on the composition of fish species and functional groups, the application of 16 multidimensional diversity indices, and the relationships between fish communities and environmental variables. A total of 120 fish species were detected. The communities predominantly consisted of species that produce sticky eggs, are sedentary, and have omnivorous diets. However, the sequence reads of species producing drifting eggs, migratory, and carnivore fish groups were higher in autumn and winter compared to spring and summer. Except for the functional evenness index (FEve), all other functional diversity indices, as well as α diversity, taxonomic diversity, and phylogenetic diversity indices, were higher in spring and summer compared to autumn and winter. This suggests that fish diversity is greater in spring and summer due to increased fish activity during the spawning season and higher eDNA shedding and detectability under warmer conditions; however, ecological niche overlap is more pronounced during these seasons. This study provides practical experience for fish monitoring based on eDNA metabarcoding technology.

Exploring heat tolerance and acclimation capacity can provide an effective approach to evaluating species' sensitivity to extremely high temperatures due to climate warming. Despite some work on amphibian and reptile thermophysiological adaptation, related questions remain. We reviewed the literature to provide a synthesis of worldwide data on heat tolerance and to determine the relative importance of common evolutionary and environmental thermal variation in amphibians and reptiles in shaping species' heat tolerance and acclimation capacity. The phylogenetic conservatism in amphibian and reptile heat tolerance arose from distinct phylogenetic properties and thermal habitat variables, potentially attributable to their different environmental sensitivities and contrasting life-history characteristics. The heat tolerances of amphibians and reptiles showed significant correlations with thermal habitat variations, which is consistent with the climate variability hypothesis that species inhabiting thermally fluctuating environments develop broader environmental tolerance ranges. No significant association was detected between species' thermal habitat variation and acclimation capacity in these 2 taxa. This finding confirmed that the interaction between maintenance cost (i.e., overall external environments) and production cost (i.e., specific environmental variables) underlaid the evolution of thermal acclimation capacity. Our results showed the importance of adaptive evolution and phylogenetic conservation in molding thermophysiological traits in amphibians and reptiles. Future studies should focus on intraspecific associations between thermophysiological traits and phylogenetic factors in species across various environmental gradients.

Cortisol is the major glucocorticoid, which is considered to be a key factor linking the environmental stress and sex differentiation in teleosts. In the present study, we explored the possible role of cortisol in sex differentiation in a protogynous hermaphroditic swamp eel, Monopterus albus. We cloned and characterized the full-length cDNA sequences of glucocorticoid receptor genes, gr1 and gr2. A novel alternative splicing variant (gr1b) was also discovered, which lacked a 27-bp nucleotide insertion in gr1, resulting in a nine-amino-acid deletion in GR1. Real-time PCR indicated that swamp eel gr1a mainly expressed in the brain; gr1b mainly in the spleen, head kidney, kidney and muscle; gr2 mainly in the muscle. During female-to-male sex reversal, the expression levels of gr1a and gr1b decreased significantly at the stage of ovotestis III, and gr2 showed a trend of increase, and increased significantly in the testis. In the brain, acute heat stress up-regulated significantly the expression of gr1a and gr1b, while had no significant effect on gr2. However, in the ovary, heat stress only up-regulated significantly the expression of gr1b at 12 h. Serum cortisol concentration increased significantly by heat stress at 1 h, and returned to normal levels at 6 and 12 h. Cortisol injection up-regulated significantly the expression levels of gr1b and gr2, while had no significant effect on gr1a in the ovary. At the same time, cortisol injection down-regulated significantly the expression of cyp19a1a, and only decreased significantly the expression of foxl2 at 6 and 12 h. Cortisol injection up-regulated significantly the expression of dmrt1a at 6, 24 and 48 h, while only increased the expression of gsdf at 6 h. The results indicate that cortisol and GRs may play roles in sex differentiation by the regulation of gonadal differentiation-related gene expression in swamp eel.

Procypris rabaudi, commonly known as the rock carp, is an endemic economic fish in the middle-upper reaches of the Yangtze River. To enhance the understanding the biology of rack carps, a high-quality reference genome is required in different areas of study. Here, we generated the first telomere-to-telomere genome assembly and annotation of the rock carp, which spans 1.64 Gb with a contig N50 of 32.36 Mb. Hi-C assembly suggested that 99.83% sequences were positioned to 50 pseudo-chromosomes. Notably, 43 chromosomes were assembled without any gap. Through the integration of homologous-based predictions and RNA-sequencing technology, we identified 44,402 protein-coding genes, with 43,663 of them (98.3%) predicted to be functional. Furthermore, our assembled genome achieved 98.1% BUSCO completeness. This work improves the quality of the rock carp genome and provides valuable foundation for the future studies of genomics, biology and the fishery resources breeding.

To explore the patterns of differentially expressed genes (DEGs) associated with different growth rates in rock carp (Procypris rabaudi), transcriptome sequencing was performed on the muscle, liver, and brain tissues of rock carp. Subsequently, bioinformatics analysis was conducted, and 2129, 1380, and 415 DEGs were identified in the muscle, liver, and brain tissues, respectively. GO enrichment and KEGG pathway analysis revealed that genes related to appetite regulation, protein degradation and digestion, lipid transport and metabolisms, and glycolysis/gluconeogenesis were upregulated in individuals with slower growth rates. Differential expression analysis identified 21 genes associated with feeding and metabolism across three tissues, including mc4r, npy, and npry in brain tissue; fatp, fabp, pparα, and apo in liver tissue; and prss, ctrl, and cela in muscle tissue. All these genes were upregulated in the slow-growing fish. Furthermore, weighted gene co-expression network analyses, including three modules (yellow, turquoise, and brown), significantly associated with growth. A network map that included these three modules enabled the identification of a series of hub genes, including rp13a, ube2o, h6pd, etc. These genes may be key candidate genes regulating the growth of rock carp. This study contributes to a deeper understanding of the growth control mechanism in rock carp and offers a scientific basis for efficient breeding and species improvement.

Starvation is a ubiquitous stress that many fish species have to cope with. To investigate the behavioral responses under this pressure in the fry stage, black rockfish (Sebastes schlegelii) at juvenile (29 days of age, 15.2 ± 1.0 mm in total length) and young (51 days of age, 40.3 ± 1.2 mm in total length) stages were starved for 12 and 21 days, respectively. During these two periods of starvation, the starved and routinely fed individuals (serving as the control group) were sampled to be analyzed the variations in growth, survival, feeding activity, swimming ability (cruise and burst), and diet transition process. The results indicated that juveniles were more sensitive to hunger, and the point of no return (PNR) was approximately 5.5 days (19 ℃ in water temperature). In contrast, the young fish had a significantly higher tolerance to starvation because the survival rate after 21 days of starvation was still higher than 99% (20 ℃). The total length and body weight of juveniles and young fish showed different degrees of negative growth. After the starvation for 1 day, the juveniles' feeding activity on shrimps increased significantly (p < 0.05), while their cruising speed and time changed insignificantly. Similar results were observed in young fish been starved for 1–3 days. With the prolongation of starvation, however, both the feeding and cruising activities of black rockfish became significantly lower than those of the control groups (p < 0.05). The burst swimming ability did not seem to be affected by starvation time. Although the short-term starvation would not increase the young fish's predation on shrimp, it might be serviceable for improving their feeding vitality. These behavioral results would help us understand the adaptive processes and response mechanisms of fish under starvation.

As micro-particle aggregates, bioflocs may be potential baits for ingestion by triangle sail mussels and supplementary feeding raises more concerns. Besides, a plasmid carrying the green fluorescent protein (GFP) gene was transformed into floc-forming Bacillus subtilis (GFP-B. subtilis) to visualize its colonization during the bioflocs ingestion. To investigate the potential benefits of bioflocs on H. cumingii, Chlorella vulgaris diets were supplemented with nothing (control group, CG) or bioflocs accounting for the microalgae biomass at 25% (T1), 50% (T2), and 100% (T3) respectively. The community composition of bioflocs was analyzed and some species like phylum Proteobacteria, order Rhodobacterales and genus Paracoccus with potentials to improve water quality were found. Furthermore, supplementary bioflocs could reduce the concentrations of inorganic nitrogen in the aquacultural environment. Differences in growth traits across all groups were insignificant, but the digestion, metabolic and immune response of H. cumingii were promoted remarkably. Interestingly, some colonies of GFP-B. subtilis were detected in the intestines of H. cumingii from T1, suggesting H. cumingii could uptake bioflocs efficiently and intestinal colonization of B. subtilis might be accomplished. Besides, supplementary bioflocs with the highest ratio (T3) could improve the physiological status of organs and suppress the dominance of potential pathogens such as Aeromonas and Pseudomonas. It was assumed that B. subtilis might stimulate the healthy intestine development via intestinal colonization. Overall, B. subtilis-mediated bioflocs is beneficial to H. cumingii and more feeding strategies of bioflocs in H. cumingii farming are expected to be developed in future.

环境雄激素属于典型的内分泌干扰物,不仅干扰生物内分泌系统导致其生长发育受阻,还会对人体健康和生态安全造成威胁.为快速测定贝类组织中典型雄激素睾酮的质量浓度,分别在 4 种提取剂乙腈、乙酸乙酯、叔丁基甲醚、正己烷-二氯甲烷(1∶1)及 3 种净化方法超低温冷冻离心、超低温冷冻离心-净化剂、超低温冷冻离心-HLB固相萃取柱条件下提取河蚬组织中的睾酮,通过比较其回收率,优化超高液相色谱-串联质谱法测定睾酮的前处理方法.结果表明:4 种提取剂中乙酸乙酯对睾酮提取效果最好,回收率高达 101.6％;提取液经超低温(-80℃)冷冻离心法净化后回收率最高,且操作简便.在此优化条件下,睾酮在质量浓度为 0.05～1.00 μg/mL范围内与对应的峰面积呈现良好的线性正相关关系(R2=0.9989),检出限为 6.25 ng/g,定量限为 20 ng/g.不同添加水平的加标回收率为 66.4％～101.1％,相对标准偏差为 2.3％～11.6％.经本研究优化后的前处理方法,操作简便、重现性好、稳定性高,具有良好的准确度和精密度,适用于贝类样品中睾酮的提取分析.

Small-scale pond aquaculture is one of the fast-growing land use options in fragmented mountainous regions of southwest China. This study measured the quality of three purple soils from Kaizhou (S1), Bishan (S2), and Tongnan (S3) in the Sichuan Basin and assessed their potentials as aquaculture substrates through overlying water trials. The effects of the substrates on the immunity, metabolism, and thermal resistance of Hyriopsis cumingii were also investigated. Soil properties analysis showed that the three soils varied in pH, total organic matter, macro-nutrient, and micro-nutrient contents. The maximum total potassium and available potassium favorable for phytoplankton growth were observed in S3. The physicochemical parameters of the substrates in the overlying water trials concurred with the soil properties. Furthermore, soil enzymes may be used as indices of soil fishability. However, S1 and S2 soils were prone to leach noxious ammonia nitrogen (NH4+-N) and nitrite nitrogen (NO2 -N) in water columns. On the other hand, S3 soil maintained the dynamic balance of the anti-oxidant system in H. cumingii, activated the relative expression of their immune-related and metabolism-related genes, and improved their resistance to thermal stress. Principal component analysis suggested that NH4+-N and NO2 -N in the soil were key environmental factors that destroyed the antioxidant system and impeded the metabolic process of H. cumingii. Based on the findings, the soils were ranked in terms of their suitability for aquaculture as follows: S3 > S1 > S2. Our study will provide a scientific foundation for building inland aqua-culture ponds and developing land use policies in China and around the world.

Plant extracts have been implicated in biological studies for their antibacterial, antioxidant, and anti-inflammatory properties. The curative efficacy of fruit extracts (Forsythia suspensa and Prunus mume) and three common antibiotics against Aeromonas veronii (alone or in extract-antibiotic combination) were clarified in vitro by microplate assays and checkerboard methods. Then the extracts with high antibacterial activity (F. suspensa) in vitro were exposed to Hyriopsis cumingii with A. veronii infection for in vivo assessments of their protective efficacy. Subsequently, oxidative stress markers, immune enzymes, and mRNA expression of immune genes in H. cumingii were investigated. Finally, principal component analysis of the physiological biomarkers and genetic markers that respond to A. veronii infection and extract exposures was conducted. The FICI values in vitro implied the following: P. mume combined with cephalexin was antagonistic, as opposed to other combinations whose effects were commutative or indifferent. In vivo results demonstrated that A. veronii caused lipid oxidative damage led to significant decreases in antioxidant defenses and induced immune responses in H. cumingii. F. suspensa significantly enhanced alanine transaminase activities and reduced malondialdehyde levels caused by A. veronii infection in gills and hepatopancreas. It also promoted antioxidant defenses, including superoxide dismutase activities and peroxidase contents, inhibiting increased alkaline phosphatase and acid phosphatase activities. Notably, 0.6% of F. suspensa extract (dry fruits: wet H. cumingii, w/w) reversed the upregulation of glutathione S-transferase and small heat shock protein mRNA levels in hepatopancreas and remarkably improved the survival rate of H. cumingii after the infection. Building on the research, F. suspensa may represent a promising substitute for offering effective protection to H. cumingii against bacterial diseases and contribute to the transformation and upgrading of the freshwater pearl culture industry.

为探究拌饲投喂方式下,钙黄绿素(calcein,CAL)对中华倒刺鲃幼鱼不同组织抗氧化水平和脂质过氧化的影响,以及正常投喂后的恢复情况,并进一步评价CAL拌饲投喂的毒性效应,实验将含有不同剂量CAL(0、2、8和32 g/kg)的饲料连续投喂中华倒刺鲃幼鱼16 d(即毒性积累实验),随后使用不含CAL的饲料投喂暂养32 d(即毒性消除实验).毒性积累实验结果显示,在CAL拌饲投喂剂量≤32 g/kg的情况下,当累积投喂时间≤8 d时,过量的活性氧(ROS)能被中华倒刺鲃幼鱼的抗氧化系统成功清除,但更长的投喂时间(如16 d)可能产生一定的毒性效应,并导致鱼体肝胰脏和肾脏组织的氧化应激过度.毒性消除实验结果显示,经32 d正常投喂后,中华倒刺鲃幼鱼血清、肝胰脏和肾脏组织的大部分抗氧化酶指标、非酶抗氧化物、脂质过氧化产物基本恢复至安全水平.研究表明,当拌饲投喂剂量≤32 g/kg时,CAL对中华倒刺鲃幼鱼的毒性作用与累积投喂时间有着密切关系,即CAL的累积投喂时间应控制在8 d以内,标记后的幼鱼应当至少暂养32 d.研究结果对CAL在鱼类荧光标记中的安全有效使用具有重要的指导意义.

Hyriopsis cumingii has attracted attention because of its pearl production performance and water purification capacity. Realizing sustainable industrialized culture of H. cumingii or applying it to bivalve biomanipulation for controlling water eutrophication needs urgent studies about the selection of suitable algae and the effects of different microalgae on mussel physiology. To contrast molecular and biochemical effects of high-quality microalgal diets (Chlorella vulgaris, Navicula pelliculosa, and Cyclotella sp.) with toxic Microcystis aeruginosa on metabolism and immune physiology of H. cumingii, levels of related enzymes and genes were analyzed during the 28-day exposure period. Results showed that the Cyclotella sp. diet could significantly (p < 0.05) maintain higher levels of metabolic enzymes (glutamic oxaloacetate transaminase (GOT), glutamic pyruvate transaminase (GPT), pyruvate kinase (PK), and hexokinase (HK)) and genes (CPT1 and LDLR). C. vulgaris and N. pelliculosa treatments significantly (p < 0.05) reduced activities of these metabolic parameters. The M. aeruginosa treatment significantly (p < 0.05) enhanced levels of immune enzymes (alkaline phosphatase (AKP), superoxide dismutase (SOD), and catalase (CAT)) and genes (HcIL-17 and IAP) on day 1 or 7, and there was a significant (p < 0.05) reduction on day 28. Results suggested that Cyclotella sp. was the suitable algae for H. cumingii, followed by C. vulgaris and N. pelliculosa, and toxic algae caused metabolic disorders, immune injury, and poor physiological status. The study has practical significance in the sustainable cultivation of H. cumingii and provides a theoretical basis for bivalve biomanipulation in eutrophic water.

Thyroid-stimulating hormone (TSH) is an important glycoprotein in hypothalamic-pituitary-thyroid axis, which plays a crucial role in the synthesis and release of thyroid hormones in vertebrates. Rice field eel, Monopterus albus, a protogynous hermaphroditic fish, which undergoes sex reversal from a functional female to a male, is an ideal model to investigate the regulation of sex differentiation. In this study, we obtained the cDNA sequence of thyroid-stimulating hormone β subunit (tshβ) from rice field eel, which contained a complete open reading frame and encoded a putative protein of 151 amino acids. Multiple alignment of protein sequences showed that tshβ was highly conserved in teleost. The tissue distribution indicated that tshβ showed high expression in the pituitary, moderate expression in the brain region, gonad, intestine and liver, and low expression in other peripheral tissues. During natural sex reversal, the expression of tshβ had no significant difference in the pituitary. Compared to that in the ovary, the expression of tshβ increased significantly in the gonad at late intersexual and male stages. After treatment by different doses of triiodothyronine (T3) (1 μg/g, 10 μg/g and 100 μg/g body weight), serum T3 and free triiodothyronine (FT3) increased sharply, while the expression of tshβ were inhibited significantly in the pituitary. Although T3 had no significant effect on the levels of serum E2, it stimulated the release of serum 11-KT at high-dose group. We also detected the effects of T3 on the expression of gonadal differentiation-related genes in rice field eel. T3 treatment inhibited the expression of foxl2, cyp19a1a and dax1, while stimulated the expression of sox9a1. These results indicate that TSH may be involved in sex differentiation, and THs may play roles in the regulation of male development and sex reversal in rice field eel.

The goldstripe ponyfish is a small tropical economic fish in the Leiognathidae family. The genome of this fish was assembled as 24 chromosomes with a total length of 577.66 Mb and 54.81 Mb unanchored contigs using HiFi and Hi-C sequencing technologies. There are 256.7 Mb of repeat elements, which cover 40.59% of the genome, and 21,506 coding genes, which cover 47.68%. According to phylogenetic analysis, the goldstripe ponyfish is closely related to the Sillaginidae family’s Chinese sillago. The distance between goldstripe ponyfish and Chinese sillago in the hierarchical clustering of gene family contractions and expansions is also the shortest, indicating a similarity even greater than that between croakers of the same family (Sciaenidae). The goldstripe ponyfish and Chinese sillago share 25 identical contracted gene families, the majority of which are immune recognition receptors, such as innate immunity-related C-type lectin and butyrophilin families, as well as acquired immunity-related T-cell receptor region V and the surface glycoprotein CD4, implying that these two fishes’ immune systems may adopt similar evolutionary strategy at the genomic level. Additionally, the positively selected genes of the Chinese sillago and the goldstripe ponyfish were enriched in biological functions involved in the cell cycle, such as telomeres, which may account for the disparities in body size and lifespan between the two species.

为调查短颌鲚(Coilia nasus)在三峡库区的资源现状,自2019年7—12月于三峡库区的长江一级支流澎溪河、梅溪河、草堂河、大宁河共采集短颌鲚样本459尾,用以分析三峡库区现有短颌鲚的年龄结构及生长特征.研究结果显示,三峡库区短颌鲚群体由1—6龄组成,1龄即可达性成熟,群体中1—3龄个体占比90.85％;群体平均体长为(16.57±0.21)cm,平均体重为(19.14±0.78)g;群体的体重-体长关系式为W=0.0038L2.957(R2=0.99),属于异速生长类型;雌性的Von Bertalanffy生长方程为Lt=38.567[1–e–0.196(t+0.985)],Wt=183.029[1–e–0.196(t+0.985)]2.938;雄性的Von Bertalanffy生长方程为Lt=34.711[1–e–0.26(t+0.603)],Wt=143.599[1–e–0.26(t+0.603)]2.995;雌、雄性体重生长的拐点年龄分别为4.62龄和3.62龄.研究结果表明目前三峡库区短颌鲚属个体小型化群体,年龄结构简单,种群数量呈上升趋势,且群体中雌性占比较高,繁殖潜力充足.因此,为保护三峡库区水域生态系统的安全与稳定,需进一步开展有关短颌鲚对三峡库区水域生态系统的影响及其风险评价的研究.

Rock carp, Procypris rabaudi, is a vulnerable carp endemic to the upper reaches of the Yangtze River and included in the National Key Protected Wildlife in 2021 as a second-class aquatic animal. Evaluating the genetic makeup of released individuals before a restocking activity is carried out is essential, and a molecular marker with simple, rapid, and universal characteristics will be helpful to the evaluation. In this study, the genetic diversity and structure of rock carp from two representative hatcheries [Yibin (YB) and Wanzhou (WZ)] and a section of the upper Yangtze [Zhuyang (ZY)] were investigated using three mtDNA markers to select one marker instead of genetic evaluation of release. The results of three mtDNA markers revealed basically the same, indicating that the level of genetic diversity in rock carp was low, and there was significant genetic differentiation between the ZY and YB. Except for Cyt b–labeled YZ (0.81) and D-loop–labeled WZ (0.59), most of the haplotypic diversity values (h) were below 0.5, the nucleotide diversity values (π) of each group were lower than 0.5 × 10-2, and the haplotype number of rock carp is 1 to 4. Among the three mtDNA markers selected, D-loop marker detected higher diversity, more haplotypes, and private haplotypes, and significant differences between the YB and WZ. The results in this study pointed out the importance of pre-release genetic evaluation and the urgency of protecting the genetic diversity of rock carp, and the D-loop marker was preferentially selected in the pre-release genetic evaluation of fish. Hatchery release is the main strategy for the recovery of rock carp populations, similar to more than 20 endemic fish species in the upper Yangtze River. This study has guiding significance for the protection and restoration of other endemic fishes in the Yangtze River by hatchery release.

为了预测三峡库区外来鱼类短颌鲚（Coilia nasus）在库区的种群发展趋势，评估其对库区水域生态系统的影响，基于碳氮稳定同位素技术，分析了三峡库区腹地，包括长江一级支流草堂河、大宁河，现有短颌鲚及杂食性和肉食性典型鱼类的营养级，在此基础上选择4种与短颌鲚营养级相近（包括太湖新银鱼Neosalanx taihuensis、翘嘴鲌Culter alburnus、鳡Elopichthys bambusa、大眼鳜Siniperca kneri）,及1种食谱存在较大重叠的鱼类（即鳙Aristichthys nobilis）,探讨了其营养生态位特征。结果显示，三峡库区短颌鲚δ 15 N值分布范围为12.112‰—14.497‰,营养级为3.762±0.196 （Mean±SD）,低于太湖新银鱼，并高于大眼鳜、翘嘴鲌、鳡及鳙；三峡库区短颌鲚δ 13 C值分布范围为-27.236‰—-22.952‰,变幅低于鳙，高于太湖新银鱼、大眼鳜、翘嘴鲌及鳡，δ 13 C值分布频率呈单峰型与太湖新银鱼高度接近，表明短颌鲚在该水域食性广泛，且与太湖新银鱼的摄食偏好趋近。据此推测三峡库区短颌鲚营养级较高的主要原因是短颌鲚在三峡库区食物来源广泛，决定其富集 15 N途径可能更丰富。此外，营养生态位分析结果显示三峡库区短颌鲚营养生态位宽幅低于鳡、鳙，高于太湖新银鱼、翘嘴鲌、大眼鳜，据此推测三峡库区短颌鲚对饵料需求的特化程度可能不高，从营养角度对环境的适应性较强；且其与营养级相近鱼类的营养生态位重叠程度较低，存在明显的营养生态位分化，种间竞争不激烈。综上所述，从目前三峡库区现有短颌鲚营养生态位特征来看，其种群规模仍有进一步扩大的可能。上述研究结果可为全面了解三峡库区外来鱼类的适应对策提供研究思路和基础数据。