Rotifers are closely related to the process of lake eutrophication and can rapidly respond to changes of water environment.In this study,we selected five small shallow lakes with different nutrient levels in Hanyang water network to explore the spatiotempo-ral changes of rotifer community structure and species diversity and its driving factors,in order to provide scientific basis for lake eco-logical restoration and biodiversity protection.Twenty-six sites were investigated in June(summer),September(autumn),December(winter)of 2021,and March(spring)of 2022,respectively.Most of the environmental and biological factors in the water network had significant spatiotemporal difference.In total,51 species of rotifers were collected and dominated by Anuraeopsis fissa,Filinia longiseta,Keratella cochlearis,Polyarthra trigla and Trichcoerca similis.The average annual density of the five lakes ranged from 109.65 to 995.92 ind./L,and the average annual Shannon-Wiener index and Margalef index ranged from 0.86 to 1.68 and 0.65 to 1.44,respectively.Non-metric multi-dimensional scale analysis revealed significant seasonal difference in rotifer community struc-tures,with relatively small spatial difference except for Lake Houguan.Multiple stepwise regression analysis showed that rotifer spe-cies number and Margalef index were mainly affected by protozoa density;rotifer density was mainly affected by phytoplankton densi-ty;Shannon-Wiener index was mainly affected by water temperature.Canonical correspondence analysis(CCA)showed that the spa-tiotemporal changes of rotifer community structure were related to water temperature,ammonia nitrogen(NH3-N),transparency(SD),total nitrogen(TN),phytoplankton density and cladocera density.Within a specific region,the segmented linear regression model demonstrated a positive correlation between the complete nutrient status index(TLI(∑))and the species,density,and diver-sity index of rotifers.When the TLI(∑)reached about 70,the species,density,and diversity index of rotifers showed a downward trend.

The impacts of the construction of hydropower projects on fish are of particular concern.To understand its effects on fish diversity from the Xiangjiaba Reservoir in the lower Jinsha River,quantitative surveys were conducted for the spatial distribution of taxonomic and functional diversity of fish assemblages in Shaonvping,Suijiang and Huixi sections,located in the lower,middle and upper streams of the reservoir,respectively,during 2016-2018.Combined with the data before(2011)and at the beginning(2015)of impoundment,the change in fish diversity in different dimensions in the lower reaches of the Jinsha River due to im-poundment was discussed.Eurytopic and limnophilic fish species such as Pseudobagrus vachelli and Hemiculter leucisculus domina-ted the Xiangjiaba Reservoir.P.vachelli and H.leucisculus accounted for 30.15％±14.82％and 13.91％±11.16％in abundance,respectively.Nonmetric multidimensional scaling showed that the fish community structure was more similar between Shaonvping and Suijiang sections.In contrast,fish community differed from Shaonvping and Huixi sections.In Suijiang section,fish communi-ties in the three periods(before,during and after the impoundment)were significantly different,indicating that fish communities in Suijiang section have undergone dramatic changes after the impoundment.Higher values of Margalef index,Shannon-Wiener in-dex and Pielou index of fish in different river sections of the reservoir area were shown as follows:Huixi＞Shaonvping＞Suijiang;Taxonomic diversity index and taxonomic differencess index were shown as follows:Huixi＞Suijiang＞Shaonvping.The spatial pat-tern of functional diversity(functional richness,functional evenness and functional divergence)in different dimensions of fish feeding,movement and reproduction in the reservoir area was different.Generally,the highest functional richness and the lowest functional evenness were found in Suijiang Section.The species and taxonomic diversity in Suijiang section showed a decreased trend compared with that before impoundment.The functional richness and evenness also showed a decreased trend.Functional traits of different dimensions,such as feeding,movement and reproduction,had significant changes after impoundment.For exam-ple,the dominant fishes changed from the species with inferior position mouth and fusiform body shape to those with terminal posi-tion mouth and compressiform body shape.Different diversity indices focus on different aspects of fish diversity.The combination of multiple index analysis is conducive to a more comprehensive understanding of the response of fish communities to environmental changes and external disturbances.This study improved our understanding on the effects of hydropower projects on fish diversity in the lower Jinsha River,provided a scientific basis for fish conservation,and surveyed data for ecological effect assessment of Ten-Year fishing Ban.

Aims: Pelteobagrus vachelli is an important economic fish in the Yangtze River. Nevertheless, it shows a trend of younger age and miniaturization, and the number of reproductive population above the third age was small, which is not benefit to the long-term maintenance of its resources. Therefore, more attention and conservation measure are needed for this species. The aim of this study is to clarify genetic diversity and genetic structure of P. vachelli.Methods: We collected 136 samples of eight different river sections（Taipingxi, Banan, Hechuan, Minjiangkou, Yibin,Shaonüping, Huixi, Fengjiaping） from the Three Gorges Dam to Baihetan Dam in the upper Yangtze River.High-throughput SNP（single nucleotide polymorphism） markers through genome re-sequencing method was used to study genetic diversity and genetic differentiation of P. vachelli populations.Results: The number of SNP and nucleotide diversity of Taipingxi and Banan populations in the Three Gorges Reservoir region were significantly higher than those in the other populations, and there were three genetic branches and abundant genetic sources in the two populations. However, there was only one genetic branch and single genetic source in Minjiangkou, Yibin, Shaonüping and Fengjiaping populations. The populations could be divided into three distinct genetic groups with great genetic differentiation. All individuals in Fengjiaping and Minjiangkou belonged to group 1, all individuals in Shaonüping and Yibin belonged to group 2, Huixi and Hechuan populations had two genetic branches（group 1 and group 2）, and Banan and Taipingxi populations had three genetic branches（group 1, group 2 and group 3）. The SNP number and nucleotide diversity were significantly affected by channel slope. The genetic differentiation was not related to geographical distance and isolated time. Conclusion: The upstream populations with lower genetic diversity are more prone to genetic drift and thus need more attention in the fish protection. There are three distinct genetic structures in the upper Yangtze River, which can be regarded as three different genetic units for management of germplasm resource.

为了探讨DNA条形码在三峡库区鱼类辅助物种鉴定中的适用性,本研究通过在三峡库区大规模采样,共采集鱼类标本18 466尾,PCR扩增了其中946尾标本的COⅠ基因序列(639 bp),在NCBI和BOLD数据库中比对鉴定出 71个物种,隶属于6目14科55属,其中5个为未命名种,鉴定率为93%;种间遗传距离(6.88%)是种内遗传距离(0.36%)的19.11倍;贝叶斯系统进化树显示,71个物种各自聚为一支且具有高的支持率(PP=1.00).遗传多样性分析显示,三峡库区中鲢Hypophthalmichthys molitrix、瓦氏黄颡鱼Tachysurus vachellii和蛇(句)Saurogobio dabryi具有较高的COⅠ条形码遗传多样性,而贝氏(鱼)Hemiculter bleekeri、光泽黄颡鱼Tachysurus nitidus和短颌鲚Coilia brachyg-nathus的较低.本研究验证了DNA条形码在三峡库区大部分鱼类鉴定中的有效性,同时构建了三峡库区鱼类DNA条形码数据库,评估了6个优势物种的遗传多样性,为三峡库区鱼类资源保护和管理提供了科学数据.

Aims:The functional characteristics of species are the key factors linking community structure and function.Studies on functional diversity seeks to understand the important relationship between community structure and function.The Three Gorges Dam is currently the world's largest hydropower project.The dam's construction blocked fish migration,altered river habitats,and dramatically changed fish species and distribution.Our study contributes to understanding of the spatial pattern of fish community structure and diversity after the impoundment of the Three Gorges Reservoir and clarifies the relationship between species diversity and functional diversity. Methods:In order to explore the spatial pattern of fish community structure and functional diversity,field investigations were conducted in the main stream and tributaries of the Three Gorges Reservoir area from 2019 to 2020.The main stream includes Zigui,Yunyang and Banan which are located in the upper,middle and lower reaches of the reservoir,respectively.The tributaries contain Xiakou(downstream of Xiangxi River),Gaoyang(downstream of Xiaojiang River)and Hechuan(downstream of Jialing River).They are located at the head,middle and end of the reservoir,respectively.We analyzed the structure and diversity of fish communities and explored the spatial patterns of functional diversity of fish by three characteristics:food acquisition,locomotion and reproduction. Results:A total of 78 species belonging to 6 orders,15 families and 56 genera were collected in the Three Gorges Reservoir.Eurytopic and limnophilic fish species dominated the reservoir.The limnophilic species,such as Coilia brachygnathus and Hemiculter bleekeri,had higher relative abundance in the Zigui,Xiakou and Gaoyang sections.In Yunyang,Banan and Hechuan river sections,the relative abundances of eurytopic species such as Saurogobio dabryi and Pelteobagrus nitidus were high.Non-metric multidimensional scales(NMDS)and Bray-Curtis dissimilarity index analyses indicated that differences in fish community structure were greatest between Hechuan and Zigui,and most similar between Xiakou and Gaoyang.Margalef richness index(D),Shannon diversity index(H')and Pielou evenness index(E)gradually increased from Zigui,through Yunyang to Banan in the main stream of the reservoir.In the tributaries,species diversity was highest in Xiakou,with lower diversity in Gaoyang and lowest in Hechuan.The spatial variation of functional diversity related to fish food acquisition,locomotion and reproduction were relatively consistent throughout the study area.The highest value was observed in Zigui and lowest in Hechuan.The total functional diversity had a consistent spatial variation with community species diversity in the Three Gorges Reservoir.The diversity indices gradually increased in the main stream from Zigui to Banan.In the tributaries,diversity indices were the highest in Xiakou,followed by Gaoyang and Hechuan. Conclusion:Overall,there are evident spatial differences in fish community structure and diversity in the Three Gorges Reservoir area.Functional diversity is more sensitive than species diversity to changes in fish community.

三峡库区为四大家鱼提供了广阔的肥育场所,在长江四大家鱼资源保护中具有非常重要的作用.目前关于库区四大家鱼种群结构和生长状况还不清楚,不利于其资源保护.2019 年 8 月-2020 年 8 月对三峡库区鲢(Hypophthalmichthys molitrix)的资源现状进行了调查,采集了 388 尾样本,分析了其年龄结构与生长特征.结果显示:采集到的鲢体长为100～805 mm,其中84.54％的鲢分布在100～400 mm;体质量为14.8～9166.3 g,其中82.22％的鲢分布在1.0 kg以下;年龄组成为1～7 龄,其中90.98％的鲢为1～3 龄.三峡库区鲢体长(L)与体重(W)呈显著的幂函数关系:W=8×10-6L3.1389(n =388,R2 =0.981),为匀速生长类型.体长与鳞径(R)呈显著的线性函数关系:R=0.0062L-0.0834(n=388,R2 =0.951).体长、体重生长方程分别为:Lt=1014.50[1-e-0.1783(t+0.0455)];Wt=21848.11[1-e-0.1783(t+0.0455)]3.1389.拐点年龄为ti=6.4龄,对应的体长、体重分别是:Lt=693.03 mm,Wt=6605.67 g.与历史数据相比,三峡库区鲢种群表现出小型化趋势,主要体现在小个体鱼比例增加以及生长速度减慢.

Impacts of hydropower projects (Three Gorges Dam and Xiangjiaba Dam) on genetic diversity and population differentiation of silver carp (Hypophthalmichthys molitrix) in the upper reaches of the Yangtze River were examined．Mitochondrial cytochrome b (Cyt b) was analyzed in silver carps from Xiangjiaba Reservoir (Shaonvping), the main stream (Banan, Fengdu, Wanzhou, Taipingxi) and tributaries (Jiantanhe, Jialingjiang, Xiaojiang) of the Three Gorges Reservoir．The haplotype diversity was found to range from 0.770 to 0.876, nucleotide diversity range from 0.687% to 1.967%, suggesting high levels of genetic diversity． Mismatch distribution in 8 populations showed unimodal distribution．Tajima’s D and Fu’s FS test values were either positive or negative, but statistically insignificant, indicating that these sliver carp populations were stable．AMOVA analysis found that 95.87% of genetic variations occurred within populations, 4.13% occurred among populations．Pairwise FST values suggested that there was no significant genetic differentiation between each population pair, other than those between Jiantanhe and Xiaojiang, Taipingxi populations. Mantel test suggested no correlation between extent of genetic differentiation among populations and geographic distance. Haplotype network suggested no apparent genealogical geographic pattern．We urge to strengthen the protection of genetic resources, and to protect differentiated populations．

为了了解三峡大坝、向家坝等水电工程建设后长江上游草鱼的遗传多样性和群体结构,利用线粒体Cyt b基因分析了长江上游邵女坪、巴南、万州、太平溪、合川等5个草鱼群体的遗传多样性、种群历史动态及群体之间的遗传分化.结果 显示,长江上游草鱼群体的遗传多样性较低,5个群体的单倍型多样性为0.618～0.800,核苷酸多样性为0.088％ ～0.112％.5个群体的错配分析图呈单峰分布,表明长江上游草鱼在历史上发生过瓶颈效应和种群扩张.分子方差变异分析(AMOVA)显示草鱼群体的遗传变异主要来自群体内部(96.96％),仅有3.04％的变异来自群体之间.群体之间的遗传分化指数FST显示邵女坪群体和合川群体之间存在显著的遗传分化,其余群体之间遗传分化不显著.

[目的]为了探讨线粒体COI基因作为DNA条形码在鳅科鱼类物种鉴定中的有效性及在系统进化关系分析中的适用性,对鳅科鱼类3亚科18属61种共358条线粒体COI基因序列进行了分析.[结果]61种鳅科鱼类的种内和种间的平均遗传距离分别为0.010和0.162,种间平均遗传距离是种内平均遗传距离的16.2倍.鳅科鱼类遗传距离在种内、种间重叠较少,能形成一定的DNA条形码间隙.ABGD分类把61个物种划分为66个OTUs,OTUs的划分与距离法基本一致.系统聚类中,有6组鱼类物种个体间相互混杂,不能按各自的物种聚类,有4个物种分化成明显的两支,46个物种能按各自的形态学分类分别聚成单支.南鳅属、花鳅属、似鳞头鳅属、瘦身鳅属和泥鳅属中部分物种没有按其形态学分类的属聚在一起.沙鳅亚科能形成单系,但条鳅亚科和花鳅亚科不能形成单系.在研究中,COI条形码可以鉴定鳅科鱼类75.41％的物种,另外,COI条形码也能够明确大多鳅科鱼类属和亚科的分类地位,研究结果可为鳅科鱼类的物种鉴定和系统分类提供参考.

为了解人工养殖的克氏原螯虾(Procambarus clarkii)亲虾的生长和形态性状,为人工放养亲本的选择提供参考依据,测定了342尾体重大于20 g的克氏原螯虾的体重(W)、全长(TL)、头胸甲长(CL)、头胸甲宽(CW)、螯足长(ChL)和螯足宽(ChW),比较了雌性和雄性生长和形态参数的差异性,模拟了各参数间的回归方程,并探讨了各参数间的相关性.结果 显示,雌性个体体重、螫足长和螯足宽的均值显著低于雄性,而头胸甲长和头胸甲宽的均值则显著高于雄性,全长和丰满度在雌雄之间差异不显著.雌性和雄性个体的优势全长范围均为90～119.99 mm,优势体重范围分别为20.0～39.9 g和30.0～44.9 g.克氏原螯虾全长-体重的关系为W♀=0.000 01×TL3.3813、W♂ =0.000 01×TL3.2309,雌性和雄性均为正异速生长;头胸甲长-体重的关系为W♀=0.000 1×CL3.2155、W♂=0.000 2×CL3.1798;头胸甲长-全长的关系为TL♀=2.928 6+2.027×CL、TL♂=-5.036 9+2.370 1×CL;头胸甲宽-头胸甲长的关系为CL♀=5.479 2+1.942 3×CW、CL♂=9.646 8+1.765 6×CW;螯足宽螯足长的关系为ChL♀=-13.721+6.679×ChW、ChL♂=-4.828+6.148 7×CW.相关性分析表明,总体上6个参数之间均有显著的正相关关系,其中与体重相关性较高的为全长和头胸甲长与宽.