三峡水库蓄水后长江上游鱼类群聚沿河流-水库梯度的空间格局（英文）

研究对2005—2012年长江上游合江、木洞、万州和秭归江段的鱼类群聚结构进行了调查,以分析三峡水库蓄水后长江上游鱼类群聚沿河流-水库梯度的空间格局。结果显示,在三峡蓄水后,在合江至秭归江段累计采集到土著鱼类368706尾,合计132种,隶属于17科,其中鲤科鱼类为优势类群。沿河流-水库纵向梯度,土著鱼类物种数下降而外来鱼类物种数增加。对应分析表明,合江至秭归江段的鱼类群聚呈现出明显分化:库区以上河段鱼类组成以流水性鱼类为主,库区鱼类则以静水缓流型为主。指示物种分析进一步指出,河流区鱼类以犁头鳅(Lepturichthys fimbriata)、红唇薄鳅(Leptobotia rubrilabris)、圆口铜鱼(Coreius guichenoti)、圆筒吻(Rhinogobio cylindricus)等22种鱼类为指示物种,其功能群特征表现为偏好流水生境、生活史为均衡主义及食性为昆虫食性;库区鱼类以宽口光唇鱼(Acrossocheilus monticolus)、宽鳍鱲(Zacco platypus)、鳊(Parabramis pekinensis)、鳙(Aristichthys nobilis)等16种鱼类为指示物种,其功能群特征表现为偏好静水生境、食性为草食性或浮游食性。以上研究表明,三峡水库蓄水导致的水环境变化是影响长江上游鱼类纵向格局的主要驱动力。建议相关管理部门根据不同河段鱼类群聚特征制定不同的渔业管理措施,如保护土著鱼类资源、控制外来入侵鱼类。     

三峡水库175 m试验性蓄水期库区及其上游江段鱼类群落结构时空分布格局

根据2010—2012年在三峡水库及其上游江段5个江段的商业性渔获物调查结果,对该区域鱼类群落结构的时空分布格局进行了分析。调查中共收集到鱼类87种,隶属于8目18科63属。沿坝前江段溯河而上至库尾以上流水江段,鱼类种类数逐渐增加。采用聚类分析(CA)和非度量多维标度(NMDS)方法对三峡水库175 m试验性蓄水期间各江段的鱼类种类组成进行分析,发现这5个调查江段的鱼类种类组成可以分为两个类群:类群Ⅰ包括秭归、巫山、云阳3个库区的江段,其鱼类种类组成在各年间的差异程度较大;而类群Ⅱ包括库尾的涪陵江段以及上游的江津江段,其鱼类种类组成在各年间差异程度较小。采用CA和NMDS方法对鱼类群落结构时空分布格局的分析结果表明,5个调查江段的鱼类群落结构在各年间可以分为不同类群;云阳与涪陵江段的鱼类群落结构的相似性逐年增加,而与秭归、巫山江段的相似性逐年减少;涪陵江段与江津江段的鱼类群落结构相似性也呈逐年减少趋势。总体而言,175m试验性蓄水对库中和库尾江段的鱼类群落结构的影响较大,但对库首以及库尾以上流水江段的影响均较小。     

怒江流域鱼类多样性及空间分布格局

怒江是我国西南地区重要的国际河流, 也是全球生物多样性热点区域之一。受地理位置和地形条件限制, 目前尚缺乏怒江流域鱼类物种多样性及其分布格局的系统研究。本研究利用近5年的全流域实地采样数据, 结合文献资料, 系统整理了怒江流域鱼类物种组成信息; 利用聚类和排序方法分析了怒江流域鱼类空间分布格局。结果表明, 怒江流域共有土著鱼类85种, 隶属于5目12科47属; 外来鱼类18种, 隶属于3目8科16属, 另外实地调查发现新记录外来种2种。怒江流域鱼类多样性从上游至下游呈明显的递增趋势。根据土著鱼类组成的聚类和排序分析结果, 可以将怒江25个亚流域分为3个部分: (1)西藏自治区内的上游河段, 分布有鱼类15种, 组成以裂腹鱼类、高原鳅类为主, 具有明显青藏高原冷水性鱼类区系特征。(2)贡山至泸水的中游河段, 分布有鱼类36种, 组成兼有上游冷水性鱼类和下游喜温的鲃亚科、野鲮亚科鱼类。(3)泸水以下的下游河段, 分布有鱼类74种。下游河段干流广泛分布有喜温的鲃亚科、野鲮亚科和 亚科鱼类, 支流则分布有数量众多的南鳅属(Schistura)、纹胸鮡属(Glyptothorax)鱼类, 鱼类组成以适应流水、激流环境的热带亚热带鱼类为主。2017-2021年的多次调查仅发现土著鱼类43种(占历史记录的50.6%), 土著鱼类资源衰退明显。过度捕捞、支流小水电开发、外来鱼类入侵等是主要威胁因素。随着人类活动的急剧增多, 怒江流域鱼类将面临更大的威胁, 亟需从流域层面开展系统的鱼类资源管理和保护规划。     

梵净山及邻近地区鱼类资源的现状

为了了解梵净山及邻近地区鱼类资源的现状及变化趋势,2001–2003年对这一地区乌江水系和沅江水系鱼类进行了系统的调查。本调查设立了19个调查点,共采集鱼类标本3614号,经鉴定为85种(亚种),分属5目14科61属。除胡子鲇(Clariasfuscus)为外来种外,其他均为土著鱼类。海南拟餐(PseudohemiculterHainanensis)、峨眉后平鳅(Metahomalopteraomeiensisomeiensis)和福建纹胸鱼兆(Glyptothoraxfukiensisfukiensis)为本地区土著鱼类新记录种。鱼类组成以鲤形目鲤科为主体,并以适应急流生活的鱼类占多数,小型野杂鱼类所占比例较高。乌江水系和沅江水系鱼类物种组成存在差异,分别属于长江上游鱼类区系成分和长江中下游区系成分。结果还表明这一地区土著鱼类物种数呈下降趋势,其中鲤形目鱼类物种数减少较多。导致该地区土著鱼类物种数下降的原因是酷渔滥捕和水域生境的破坏。     

三峡库区上游江津江段鱼类 群落结构的年际变化

为了解三峡蓄水倒灌对江津江段的鱼类群落结构的影响,于2006—2012年在三峡库区上游的江津江段进行了商业渔获物调查。结果表明:调查共发现鱼类67种,隶属于3目10科45属;175 m蓄水后江津江段的鱼类种类数减少;种类组成的聚类分析(CA)表明,2006—2012年的鱼类种类组成分为2组,其中一组为2006、2007、2008和2010年,一组为2011和2012年,鱼类种类组成开始发生变化的年份为2010年;one-way ANOSIM检验显示,2组之间在统计学上差异不显著(R=0.96,P=0.07);CA和非度量多维标度(NMDS)方法的结果均表明,2006—2012年的鱼类群落结构可以分为2组,但one-way ANOSIM检验结果也显示,两组间在统计学上无显著性差异(R=1.00,P=0.07);百分比相似性分析(SIMPER)结果表明,2006—2012年丰度减少的种类为喜流水性的鳅科和平鳍鳅科鱼类,而丰度增加的种类为小型的流水性鱼类或能够适应静、缓流水的鱼类。总体而言,江津江段的鱼类群落结构受175 m蓄水的影响程度大于受以前各期蓄水的影响程度。     

三峡水库不同区域对鱼类群落结构和鱼类组成动态的影响(英文)

研究选取三峡水库三个不同的区域来研究离坝距离对鱼类群落结构和鱼类组成动态的影响。2010年11月到2011年10月期间共采集了8680尾鱼类样本,隶属于11科58种,其中鲤科鱼类占据了三峡水库鱼类的主体。夏季时的鱼类丰度显著高于其他季节的(P0.05)。鱼类物种多样性与丰度在靠近大坝的江段(秭归)最低,中游江段(万州)相对较高,远离大坝的江段(涪陵)居中。随着三峡大坝的建成,鱼类区系也由适应流水生存的种类转变为适应静水生存的种类。因此,三峡水库蓄水已经明显地改变了其原有的鱼类群落结构,鱼类组成的相对丰度也随着时间发生了改变。     

新疆伊犁河不同河段鱼类的物种多样性和优势种

为了了解伊犁河鱼类群落结构和多样性特征, 于2012—2014年连续3年对我国境内新疆伊犁河上、中和下游不同河段进行鱼类资源调查。获得27种鱼类样本, 隶属于6目9科23属。伊犁河中、上游河段主要以斯氏高原鳅、新疆裸重唇鱼、新疆高原鳅和伊犁裂腹鱼等土著鱼类为优势种, 下游河段的优势种主要有鲤、草鱼和鲫等外来种。伊犁河中、上游河段鱼类种类稀少, 大中型鱼类资源稀少, 鱼类群落多样性低。梯级水电站的开发、过度捕捞以及外来种入侵对伊犁河鱼类鱼类群落造成了很大的影响。     

长江上游三层流刺网渔业现状的调查

1997-1999年对长江上游宜宾江段和合江江段的三层流刺网渔业现状进行了调查。合江江段三层流刺网内网目在10-180mm之间,宜宾江段以50mm以下的网目为主。采集到的鱼类有59种,包括17种长江上游特有鱼类;渔获物组成存在区域、季节和年际之间的差异。目前长江上游的捕捞强度比70年代显著提高。     

三峡库区支流生境因子对库区蓄水的响应

三峡水库的运行调度,使库区支流形成了截然不同的3种河段类型:完全受水库蓄水影响的145m回水段(完全河段),既受蓄水影响又受自然洪汛影响的145—175m回水段(双重河段)以及不受蓄水影响的大于175m的自然河流段(自然河段)。为明确库区蓄水对河流不同河段生境因子的影响程度及差异,对三峡库区36条重要支流的254个河段进行河流生境调查,进行不同河段下生境指标的因子分析,并进一步分析水文情势自然性与不同河段各生境因子的相关关系。结果表明,植被状况对3种不同河段来说均为重要生境因子,但受三峡水库蓄水影响,完全河段植被结构不完整;受库区蓄水影响,完全河段与双重河段及自然河段相比,流速流态状况、表层覆盖物状况、河岸带宽度、湿润率等生境因子有明显改变;水文情势自然性对不同河段生境因子的影响不同。     

三峡水库生态渔业发展策略与关键技术研究分析

针对三峡水库蓄水后水体资源丰富、水生态系统发育尚不完善、支流库湾藻类水华问题较严重、鱼类群落结构有待调控、水生生物资源未有效利用和转化的现状, 阐述了三峡水库生态渔业作为生态系统保护途径和绿色产业的必要性与重要性, 提出了三峡水库生态渔业发展的总体目标与基本原则, 认为三峡水库发展生态渔业应以生态安全保障和水质养护为首要任务, 严格控制外来物种的引种移植, 以土著鱼类自然繁殖保护和捕捞管理为主, 动态调控放流增殖的鱼类种类和数量为辅, 建立以鱼类群落合理配置和食物网结构优化为手段的水库生态系统调控技术体系, 促进高效的物质循环和能量流动, 实现环境保护和渔业增效的双赢。作者围绕渔业放流增殖、野生鱼类资源保护、捕捞管理、局部库区渔业调控、渔业生物控藻、社区渔业协调管理、生态渔业总体规划等方面, 分析了现阶段三峡水库生态渔业的重点研究任务与关键技术,同时建议加强相关生态学理论与方法研究、技术示范和成果应用, 为三峡水库以渔养水、渔-水和谐的综合管理提供决策依据。       

Temporal changes in fish diversity in lotic and lentic environments along a reservoir cascade

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三峡水库初次蓄水后干流库区枝角类的空间分布与季节变化

为了阐明三峡水库初次蓄水后干流库区枝角类的时空分布规律, 2004年4月至2005年1月, 在600余公里干流库区设置10个样点, 定性和定量采集枝角类标本。本次调查共采到9种枝角类, 其中春季8种, 夏季5种, 秋季2种, 冬季3种。枝角类种类组成的空间分布差异明显, 河流状态的江段有4种, 水库状态的江段有7种, 水库状态的江段距大坝越近, 枝角类种类越丰富。枝角类的密度和生物量的空间分布和季节变化规律一致, 季节间差异极显著(P<0.01), 春季最高, 夏季次之, 秋季和冬季较低; 空间分布上表现为在干流库区的纵向分布上差异极显著(P<0.01), 河流状态样点远低于水库状态的样点, 水库上游江段又低于下游坝前段。结果显示三峡水库的枝角类具有明显的纵向分布和季节变化特征。     

Immediate impacts of the second impoundment on fish communities in the Three Gorges Reservoir

Long and short term investigations have revealed dramatic changes in fish communities after impoundments by reservoirs. However, the process of these changes during impoundment remains poorly studied. In 2005 and 2006, before and during the second stage of impoundment of the Three Gorges Reservoir (TGR), in the upper reaches of the Yangtze, China, we investigated fish catches to assess the impacts of reservoir filling on fish community structure. We conducted sampling at 2 sites, Wanzhou reach, which had been inundated by the first water filling in 2003, and Fuling reach, which still remained a riverine site before this water filling. The results revealed an evident and immediate shift of fish communities from lotic to lentic components. In the Wanzhou reach, during the filling, the abundance percentage of lentic fish increased to 94% compared to 69% before the filling. In the Fuling reach, after the filling, lotic fish declined in abundance from 99% to 85%, while lentic fish increased from less than 1% to 12% in abundance. Based on our investigation and the regulation scheme of the TGR, we predicted that after the completion of the Three Gorges Dam (TGD), there would be typical lacustrine, transitional and riverine zones in TGR, with their corresponding fish assemblages. We suggest that long term monitoring should be conducted to evaluate the future ecological effects, and different strategies implemented in these three zones for conservation purposes.     

Structure of fish assemblages along spatial gradients in a deep subtropical reservoir (Itaipu Reservoir,Brazil-Paraguay border)

Synopsis We assessed the structure of the fish assemblages in the Itaipu Reservoir (Paraná River, Brazil-Paraguay) along a longitudinal or river-dam gradient (composed of riverine, transitional and lacustrine zones) and transversal or upstream–downstream gradients of the tributaries (composed of lotic and lentic stretches of tributaries and reservoir shores). We sampled stations distributed along the environmental gradients quarterly during two years. We caught mostly piscivorous, detritivorous and insectivorous fishes. The structure of the whole fish assemblage both at the regional spatial scale and at the zones of each gradient was significantly non-random according to null models and ordination analysis. When the assemblage was broken into groups, the piscivores and detritivores as well as the predators and prey showed significant non-random structure whereas the insectivores, omnivores, herbivores, benthophages and mud-eaters showed random structure. The first groups are those that had more species and the last mentioned are those with fewer species. The tributaries varied more in composition among themselves than the reservoir shores, showing a high heterogeneity in the transversal gradient. The most widespread species was the introduced piscivore Plagioscion squamosissimus. The loricariids were most abundant in the lotic and lentic stretches of the tributaries. We also observed temporal variability in species composition, mainly in the reservoir shores possibly due to the influence of the upstream floodplain on the migratory fish that periodically use the reservoir as feeding habitat. In the tributaries, the temporal changes were less predictable. A combination of habitat preferences and interactions among species, especially predator–prey relations, might be responsible for the observed structure patterns.     

二滩水电站水库形成后鱼类种类组成的演变

本文对二滩水库建成前后,雅砻江下游长约380km河段的鱼类种类结构、生态类群及相对资源量的变化进行了研究。结果表明水库建成后不同区段的鱼类种类结构发生了变化,喜栖静水和缓流环境的种类逐渐在库区占主导地位,适应急流环境的种类主要分布于库尾和支流等局部水域中,一些外来种已经定居并在某些水域形成了优势种群。在水库建成后的头几年,由于鱼类种群密度增加还导致了渔业捕捞量大幅度上升。针对上述变化,结合雅砻江梯级电站建设可能带来的进一步环境改变,作者提出了建立自然保护江段、开展人工繁殖放流、进行水库生态调度以及防止外来种入侵等措施和建议。     

Interannual variations of the fish assemblage in the transitional zone of the Three Gorges Reservoir: persistence and stability

The construction of dams may lead to dramatic changes in fish assemblages due to the loss of lotic habitat caused by impoundment, which have been well documented. However, knowledge of the temporal variation of fish assemblages in the transitional zone, which is an ecotone between lotic and lentic environments of the reservoir, is still very rare. In the present study, fishes in the transitional zone of the Three Gorges Reservoir were sampled from 1997 to 2002 and from 2006 to 2009 to investigate interannual variations of fish assemblages. The results showed that 9 families, composed of 77 species, were found in the transitional zone with Cyprinidae as the dominant group. By cluster analysis (CLUSTER) and non-metric multidimensional scaling analysis (MDS), assemblages were separated into two groups at a Bray-Curtis similarity value of 77.26%, representing the pre-impoundment period and post-impoundment period. Following analysis of similarity percentages of species contributions (SIMPER), shifts in abundances of Coreius guichenoti, Rhinogobio cylindricus and Coreius heterodon, etc. contributed most to the difference between the two groups. Surprisingly, contrasting to the drastic changes in lacustrine region, the fish assemblage in the transitional zone appeared to be relatively stable, since the ten core species caught were consistently recorded every year, and no significant species replacement occurred during our study period. Besides, the moderate index of persistence indicated persistence of the fish assemblage as well, in spite of the shift of some species. Based on the results of ordination and time-lag analysis, the fish assemblage in the transitional zone showed no directional change. We conclude that fish assemblage in the transitional zone of the Three Gorges Reservoir was stable across the surveyed years. Based on our results, we propose that maintenance of dynamic transitional zones in reservoirs will be useful for the preservation of fishes, particularly for the endemic species inhabiting the upper Yangtze.     

丹江口水库鱼类群落特征及其历史变化

为了解丹江口水库鱼类群落现状及历史变化, 作者于2018-2019年采用多网目复合刺网采样和渔民渔获物调查的方式对丹江口水库进行了鱼类群落调查。本次调查共采集鱼类33种, 隶属5目11科29属, 以鲤科鱼类为主, 占总数的63.6%。基于多网目复合刺网采样的鱼类群落多样性指数和单位努力捕捞量(catch per unit effort, CPUE, g·day ^-1·m ^-2)在各采样点间具有一定的差异。目前丹江口水库以定居性、喜静缓流、杂食性和肉食性鱼类为主。与20世纪50年代和80年代的历史资料相比, 丹江口水库鱼类物种丰富度先升高后下降; 而生态类型则呈现杂食性鱼类、喜流水性鱼类和洄游性鱼类比例持续下降的趋势。2018-2019年丹江口水库鱼类组成与20世纪80年代的相似性指数为0.35 (中等不相似), 与20世纪50年代的相似性指数为0.29 (中等不相似)。调查结果表明半个世纪以来丹江口水库鱼类群落结构发生了较大变化, 目前趋于小型化和简单化。这些变化可能是由大坝建设、渔业放养、不合理捕捞、外来鱼类引入等人类活动所致。     

Population characteristics of yellow catfish (Peltobagrus fluvidraco) along the longitudinal profile of Three Gorges Reservoir,China

The length–frequency and age distributions, condition factor (K), gonadosomatic index (GSI) and gastrosomatic index (GaSI) of yellow catfish (Peltobagrus fluvidraco) were studied at three sites along the 500‐km longitudinal profile of Three Gorges Reservoir. Across all three sites (dam, mid‐reservoir and upper reservoir), GSI increased from April through June, with peak values observed in May and June. Mean K and GSI for fish captured near the dam were significantly higher compared to mid‐reservoir or upper‐reservoir areas. The GaSI index showed no significant variations across sites. However, the length‐frequency histogram of yellow catfish in the more riverine upper reservoir was log‐normal and skewed towards larger (total length) fish, a pattern that was significantly different from mid‐reservoir or near‐dam habitats, where fish length data were normally distributed but at a smaller length mode. Age estimations using otolith sagittae revealed that the spawning population was dominated by fish from only two age‐classes (1 and 2). This study provides novel insight into population characteristics of fish along the substantial spatial scale of Three Gorges Reservoir. Given the irregular population size‐ and age‐structure and the fact that the species is currently commercially exploited, this population is believed to be susceptible to overfishing. Restricted harvesting during peak reproductive months is recommended and suggested that additional research is needed on recruitment and harvest dynamics of this species throughout Three Gorges Reservoir. Additional research is also required to determine whether the spike in K and GSI at lentic sites is a transient product of recent impoundment or an indicator of optimal hydrologic habitat for the species.     

Non-native fishes and native species diversity in freshwater fish assemblages across the United States

The proliferation of non-native species in North American freshwater ecosystems is considered a primary threat to the integrity of native community structure. However, a general understanding of consistent and predictable impacts of non-native species on native freshwater diversity is limited, in part, because of a lack of broad-scale studies including data from numerous localities across multiple drainages. This study uses data from 751 localities collected during the United States Geological Survey (USGS) National Water Quality Assessment (NAWQA) program to examine the influence of non-native fish species on native freshwater fish assemblages across the United States. In general, no significant differences in native fish richness and diversity measures were detected between sites with only native species and sites containing non-native species. However, at sites with non-native species, the number of non-native species present was negatively correlated with native species richness and Shannon diversity and positively correlated with native evenness. Non-native piscivores were negatively correlated with native species richness and Shannon diversity and positively correlated with native evenness. Native piscivores were positively correlated with native richness and diversity and negatively correlated with native evenness at sites with only native species. Our results suggest that from a superficial perspective, native species richness and diversity are not different among sites with and without non-native species. However, when patterns of native species richness and diversity are examined at sites containing non-native species, correlations between non-native and native species richness and diversity imply the expected negative effect of invasive taxa. Additionally, non-native piscivores appear to have a significant negative effect on native taxa and possibly represent a novel selective force on naive native prey.     

Longitudinal changes and indicator species of the fish fauna in the subtropical Sinos River, Brazil

This study investigated the fish fauna in the subtropical Sinos River, considering species addition and replacement and the occurrence of indicator species along a longitudinal gradient. Patterns in fish assemblage ordination evaluated by correspondence analysis reflected the headwater and lowland river reaches. Uppermost sampling stations were characterized by species with restricted occurrence and medium abundance, whereas in the lowland most species were captured only once during the surveyed period and in low abundance. Species addition prevailed between the headwater sampling stations and both addition and replacement occurred between the lowland sampling stations. Nine species were characteristic for the headwater reach and 14 species for the lowland reach.