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.

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

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.

The Three Gorges Reservoir (TGR) holds the distinction of being China's largest reservoir, and the presence of pollutants in the fish from the reservoir have a direct impact on the health of local residents. Thus, 349 fish specimens of 21 species and 1 benthos (Bellamya aeruginosas) were collected from four typical tributaries of the TGR from 2019 to 2020. These specimens were analyzed for the concentrations of total mercury (THg) and methylmercury (MeHg), and some representative samples were tested for & delta;13C and & delta;15N values to reveal the characteristics of bioaccumulation and biomagnification. The maximum safe daily consumption was estimated based on the oral reference dose (0.1 & mu;g kg- 1 bw/day according to US-EPA, 2017). The results showed that the mean THg and MeHg concentrations in fish from the TGR tributaries were 73.18 & PLUSMN; 49.21 ng g-1 and 48.42 & PLUSMN; 40.66 ng g-1, respectively, with the trophic magnification factors (TMFs) of THg and MeHg being 0.066 and 0.060, respectively. Among all the fish species in the tributaries, the highest daily maximum safe consumption amount was 1253.89 g for S. asotus consumed by adults, while the lowest was 62.88 g for C. nasus consumed by children.

以三峡库区四条一级支流(梅溪河、草堂河、大宁河和澎溪河)中短颌鲚为研究对象,在调查鱼体肌肉Cr、Mn、Ni、Cu、Zn、As、Se、Ag、Cd和Pb10种重金属污染水平的基础上,探讨了其重金属累积特征,辨析了重金属来源,并进一步评估了其健康风险.研究结果表明,三峡库区短颌鲚Cr、Cu、Zn、As、Se、Cd和Pb的平均含量均低于相应的标准限值2.00、50.00、50.00、1.00、1.00、0.10、0.50mg/kg,但与库区营养级相近的其他肉食性鱼类相比,短颌鲚表现出较强的重金属累积能力.另外,不同流域间短颌鲚体内部分重金属表现出显著的空间差异.同时,短颌鲚体内重金属的累积受到自身生长状况的影响,并且这种影响与重金属种类有关.主成分分析结果表明短颌鲚体内重金属的主要来源有化石燃料燃烧?金属冶炼和工业污水排放,同时梅溪河中短颌鲚受Zn、Cu和As影响较大,而草堂河中短颌鲚受Cr和Ni的影响较大.健康风险评估结果显示,单一(THQ)和复合重金属风险系数(TTHQ)均小于1,表明目前食用三峡库区短颌鲚不会威胁人体健康,但其中As对TTHQ的贡献率高达77%.本文研究结果可为长江食物网中重金属的研究提供基础数据.

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.

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.

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。

Calcein (CAL), as a simple and effective fluorescent marker, has been widely used in the labeling of fish and shellfish for the past few decades. In the present study, a series of CAL doses (including 0, 25, 100, and 200 mg/kg) were injected into juvenile Hypophthalmichthys molitrix, which were then fed with feed without CAL for 32 days, to explore the effects of CAL injection on the levels of antioxidant enzymes and lipid peroxidation in different tissues. The results showed that the mortality of juvenile silver carp increased significantly in the treatment group. The increased serum enzyme activities (glutamate-oxaloacetate transaminase, glutamate-pyruvate transaminase, and alkaline phosphatase) were assumed to be due to CAL-induced hepatic damage, and the stress was mainly concentrated in the early stages after CAL injection (i.e., 0-4 d). Moreover, higher CAL doses (>= 100 mg/kg) could lead to greater toxicity in juvenile silver carp and damage the gills and hepato-pancreas, but the antioxidant systems in the gills and hepatopancreas were able to successfully eliminate the excess CAL-induced reactive oxygen species for > 16 d after CAL injection. These results confirmed that CAL injection could induce a strong oxidative stress response in juvenile silver carp and that oxidative stress was closely correlated with the injection dose and time after injection. Therefore, when CAL is used for fluorescent labeling of juvenile silver carp by injection, the injection dose of CAL should be restricted to <= 25 mg/kg, and the injected juveniles should be reared for at least 16 d. However, compared to other application methods (e.g., direct immersion, feeding, and osmotic induction), injection might not be the recommended method for marking juvenile silver carp.

为探究盐酸四环素(TCH)和茜素红S(ARS)对中华倒刺鲃(Spinibarbus sinensis Bleeker)的影响及标记效果,丰富鱼类荧光标记模式,研究使用TCH(100—500 mg/L)和ARS(100—300 mg/L)对中华倒刺鲃幼鱼进行双重浸染荧光标记,实验共设置5个处理组和1个对照组,浸染时间均为24h.结果显示,经90d的养殖实验后,标记鱼的耳石(包括矢耳石和星耳石)、倒刺、鳍条和鳍棘均能检测到双重荧光标记环,且TCH产生的黄色荧光环比ARS产生的红色荧光环更接近骨质结构内部.较高浓度处理组的矢耳石(≥300 mg/L TCH和≥150 mg/L ARS)、星耳石(≥300 mg/L TCH和≥200 mg/L ARS)和倒刺(400—500 mg/L TCH和150—300 mg/L ARS)中均能检测到明显的标记环(n≥2),但所有处理组的侧线鳞和非侧线鳞的荧光标记不明显(0≤n≤1).经200—500 mg/L TCH和150—300 mg/L ARS处理的鳍条,及经300—500 mg/L TCH和200—300 mg/L ARS处理的鳍棘中可以同时检测到明显的TCH和ARS的标记环(n≥2).此外,在整个实验中各处理组标记鱼与对照组相比,在生长和存活率方面均无显著性差异(P>0.05).结果表明,使用TCH和ARS双重标记中华倒刺鲃幼鱼是可行的.双重荧光标记方法在水生生物标记回捕实验及实验性生物学研究方面具有潜在的应用前景.

2017年7月～2018年6月,在青海湖的洱海、大湖、黑马河口、泉吉河口、沙柳河口和布哈河口6处采样点,共采集青海湖裸鲤(Gymnocypris przewalskii)繁殖群体样本295尾,对不同繁殖群体的繁殖特性进行比较研究.结果 显示,除泉吉河口的性比(♀∶♂)＜1(即0.82∶1)外,其余5个繁殖群体雌性个体数量均大于雄性(♀∶♂＞1);6个繁殖群体的所有样本中,雌性的生物学最小型大于雄性.其中,雌性群体(布哈河口)的生物学最小型的年龄、全长和体重分别为5龄、157 mm和42.5 g,雄性(沙柳河口)为4龄、124 mm和24.5 g;6个繁殖群体的雌性性成熟系数(GSI)显著高于雄性(P＜0.05),沙柳河口雌性GSI(19.67±1.36)％显著高于洱海(10.28±1.36)％和大湖(13.35±1.24)％(P＜0.05),而不同繁殖群体雄性GSI间差异不显著(P＞0.05);黑马河口平均绝对繁殖力Ft[(3338.18±324.25)粒]和相对繁殖力Fr [(21.88±2.10)粒/g]分别与沙柳河口的Ft [(10699.40±613.91)粒]和Fr[(82.68±4.63)粒/g]存在显著差异(P＜0.05).以上研究结果表明,青海湖裸鲤的繁殖特性在不同群体之间已出现分化趋势或已经分化.本研究可为进一步了解青海湖裸鲤的种群结构以及制定合理的渔业资源管理措施提供基础数据,特别是增殖放流策略的优化.

Standard single-exposure of calcein (CAL) was conducted on juvenile silver carp, Hypophthalmichthys molitrix, to examine its effects on antioxidant enzyme levels and lipid peroxidation. Juveniles were exposed to different concentrations of CAL solutions (0, 100, 300, 500 and 700 mg/L) for different immersion periods (12, 24, 48, 72 and 96 hr). Increased glutamate-oxaloacetate transaminase, glutamate-pyruvate transaminase and alkaline phosphatases activities were assumed to be due to CAL-induced hepatic damage, probably because of the high potential of CAL to accumulate in fish hepatopancreas. Higher CAL concentrations (>300 mg/L) and prolonged immersion periods (>48 hr) could lead to greater toxicity in juvenile silver carp and, to a certain degree, damage the gills and hepatopancreas. The antioxidant responses in the gills and hepatopancreas result in successful elimination of the excess CAL-induced reactive oxygen species for CAL exposure <= 24 hr. Our results confirmed that the toxic effects of CAL on antioxidant enzyme levels and lipid peroxidation in juvenile silver carp depended on both CAL concentrations and duration of exposure. Moreover, concentration of CAL solutions and the immersion period should be, respectively, restricted to <= 300 mg/L and <= 24 hr, when CAL is used for immersion marking juvenile silver carp.

在全球渔业资源衰退的形势下,综合性大学渔业资源生物学的教学应以启发和培养学生的"渔业资源保护意识"为核心思想,紧紧围绕"促进渔业资源的可持续利用"为中心,坚持"综合考虑渔业、生态和社会3方面要素",并通过生态系统理论启发渔业资源保护意识,通过系统动力学理论搭建渔业资源保护的桥梁,通过渔业资源经济学理论优化渔业资源的开发利用,通过可持续发展理论为实现渔业资源的永续利用提供思路.

Marking fish with fluorochrome dyes has the potential to produce detectable marks in otoliths, scales, fin rays, fin spines, and other bony structures based on differential staining of chemical dyes, and it is a widely used technique for mass-marking fish that included both teleosts and elasmobranchs. This technique, which has relatively economic advantages and simple marking process, can be applied to fish of all ages, and these fluorescent marks can be retained for several months and even years. Up to now, >200 fish species have been successfully marked by this marking technique. Fluorescent labeling is a practical and available marking technique for large-scale marking hatchery-reared fish. The methodology of fluorescent labeling is reviewed, including fluorochrome labeling dyes, application method, detection, and evaluation strategies. Aspects of practical applications, limitations, and supervision of fluorescent labeling are also discussed.

Invasive alien species have posed substantial threats to freshwater ecosystems and are generally difficult and cost-intensive to eradicate once established. Therefore, it is of great importance to identify their potential distribution and take preventive actions. Species distribution modelling has been regarded as a powerful tool to identify areas that provide suitable environmental conditions for the establishment of invaders. In this study, an ensemble species distribution model was developed for the Chinese mitten crab (Eriocheir sinensis), by using 188 worldwide occurrence records and 11 environmental variables to predict its global potential distribution in freshwater habitats. The ensemble model showed high predictive performance and indicated that annual mean temperature was the most important environmental variable that limits the distribution of this invasive crustacean. The model successfully predicted the known distribution of Chinese mitten crab in its native range and invasive ranges and suggested that this invader has not yet fully realized its potential distribution in Europe and North America. The model also predicted some additional suitable areas where this crab has not yet been observed (Japan, part of South America, Australia, and New Zealand). Management strategies are proposed to control this invasive crab in light of these results.

To improve release techniques of Japanese flounder, Paralichthys olivaceus, for the purpose of stock enhancement, the substrate preference and burial behaviour over a range of sand grain sizes were investigated under laboratory conditions. Ten 12-hr trials (i.e. 10 experimental groups), which, respectively, contained two different levels of substrates, demonstrated that juvenile flounder (55–78 mm total length) selected substrate of grain size (GS) < 2.00 mm, and the degree (from high to low) of their preference could be listed as Level 3 (0.50–2.00 mm) > Level 4 (0.25–0.50 mm) > Level 5 (0.05–0.25 mm) > Level 2 (2.00–4.00 mm) > Level 1 (4.00–6.00 mm). The average burying of fish in substrates of GS < 2.00 mm was more than 93.1%. Additionally, along with food deprivation time increased from 12 to 24 hr, some flounder showed random off-bottom swimming behaviour, and the appearance of off-bottom swimming behaviour was <3.2%. These results suggest that releasing sites with appropriate substrate grain size (GS < 2.00 mm) are suitable for conducting mass releases of hatchery-reared flounder juveniles, and starvation prior to release should be minimized. The results of the present study are essential to improve stocking strategies of Japanese flounder and reduce the juvenile mortality after release.

2013年11月至2014年6月,在长江上游宜宾至江津段共采到周丛藻类4门31属82种,硅藻门在种类和数量上均占据优势地位.周丛藻类细胞密度和生物量变幅分别为0.13～13.11×10 5个/cm2和0.03～7.07 mg/cm2,总平均值分别为4.23×10 5个/cm2和1.60 mg/cm2.周丛藻类物种数、细胞密度和生物量均以秋、冬2季最高,夏季最低.从上游到下游,周丛藻类群落结构大体呈现出物种数和多样性指数逐渐减小,而细胞密度和生物量逐渐增加的趋势,水质污染逐渐加重.调查期间周丛藻类的Shannon-Wiener多样性指数、Pielou均匀度指数和Margalef多样性指数的变幅分别为1.57～4.52,0.14～0.50和2.10～3.96.基于周丛藻类多样性指数、污染指数和污染评价值等的水质评价结果大体一致,即长江上游宜宾至江津段水质为β-中污型,且有向α-中污过渡的趋势.

In the present study, phytoplankton samples were collected from the upper reaches of the Yangtze River during four consecutive seasons, from November 2013 to November 2014.The results showed that there were 95 phytoplankton species belonging to 6 phyla and 38 genera found in the investigating region.And based on the distributing range,discriminatory power and Pearson's correlation analysis of the 13 candidate indexes, five metrics, including Shannon-Wiener index, Margalef index, Pielou index, density of phytoplankton, percentage of bacillariophyta were selected to establish biotic integrity index of phytoplankton (P-IBI) evaluation system.Three score system, four score system and ratio score system were used to get metrics into a uniform score for all the sampling points, and the results showed that Gao Zhuangqiao and Yang Shi were in the state of health, Bai Sha in sub-health, and Jiang An and De Gan in the sub-health to good-fair transitional phase.On the whole, the health state of each sampling sites reflected by the three scoring methods almost the same.However, four score system and ratio score system were more meticulous on the grade classification and evaluation, thus the evaluation results of four score system and ratio score system were more accurate.The Pearson′s correlation analysis showed that the P-IBI was significantly negative correlated with TN and pH (P<0.05).

To predict the occurrence of cannibalism in the culture of larval black rockfish, Sebastes schlegelii, we developed a regression model based on morphometric measurements. First, 156 black rockfish were measured to obtain a theoretical model, that is L-T (prey) = 0.624 L-T cannibal (+) 0.835. Then, 202 trials of paired fish, together with 31 pairs of cannibalistic fish, were used to revise this model, and the practical model was constructed: L-T (prey) = 0.522 L-T cannibal + 4.908 (R-2 = 0.99). According to this equation, the threshold of size ratio was deduced, that is 1.30-1.69, which could be used to grade black rockfish by size and remove potential cannibals.

Laboratory experiments were conducted to determine the influences of size difference, fish density, shelter density, starvation time and light intensity on cannibalism among the fry of black rockfish, Sebastes schlegelii. Cannibalism of black rockfish did not occur at any level of other factors without sufficient size difference. Cannibalism rate did not exceed 0.45 when size difference was <25mm. Starvation seemed to be a primary stimulus for cannibals to practice cannibalism. Cannibalism rate increased significantly after cannibals were starved for 12h. Also, shelter density and light intensity significantly influenced cannibalism. A higher shelter density of (8 per tank) or a suitable light intensity (0.2Klux) reduced the occurrence of this behavior significantly. In addition, interactive effects between size difference and shelter density, size difference and starvation time, starvation time and shelter density, starvation time and light intensity were confirmed on cannibalism rate. However, fish density (of prey) appeared to have no significant influence on the rate of cannibalism. Based on these results, response curves and surface contour plots were developed to predict the occurrence of cannibalism, and some prevention measures were suggested in black rockfish culture.