三峡库区175 m蓄水对小江回水区主要经济鱼类能量来源的影响

2010年三峡大坝首次成功蓄水到175 m.为了探讨175 m蓄水对库区支流鱼类食物网能量来源的影响,采用稳定性同位素方法并结合多源线性混合模型(IsoSource模型)对小江回水区鲫、鲤、蒙古鲌、鲇、大鳍鳠、瓦氏黄颡鱼、光泽黄颡鱼等7种主要经济鱼类能量来源进行了分析.结果表明:蓄水前(2010年7月),微型藻类是7种主要经济鱼类能量的主要来源;蓄水后(2010年12月),微型藻类对7种主要经济鱼类能量来源的贡献比例略有下降,而陆生C4植物的相对贡献比例明显增加,特别是对杂食性鲫和肉食性鲇的贡献率分别达到了38％ ～54％和32％ ～ 50％.蓄水后,鲫和鲇至少有30％的能量来自陆生C4植物.说明三峡大坝的蓄水过程增加了外源性C4植物对鱼类能量的贡献比例.     

三峡水库蓄水初期鱼体汞含量及其水生食物链累积特征

于2011-2012年在三峡库区干流水域及7条典型支流采集了11种鱼类样品,以稳定同位素(δ13C和δ15N)营养等级分析为基础,研究了三峡水库蓄水后的鱼类汞含量水平及其食物链累积特征.结果表明,库区鱼类(以鲤为例)平均总汞含量为57.1 μg/kg,与蓄水前鱼体总汞水平相当,但在库区不同水域鱼体总汞含量差异显著:干流入库水域(洛碛断面)鱼体总汞含量平均值为88.0μg/kg,显著高于水库腹区水域(巫山断面)的平均值43.1μg/kg.稳定同位素分析表明,库区支流鱼体的δ13C范围为-22.08‰--28.92‰,大于干流鱼体的δ13C范围(-23.11‰--26.87‰),表明支流鱼类的食物来源具有更明显的湖沼型特征.同时,支流鱼类食物链上汞的累积放大效率显著高于干流水域.水文水动力差异可能是库区内汞累积等生态过程存在空间差异的重要原因.     

Comparative trophic impacts of two globally invasive cyprinid fishes reveal species‐specific invasion consequences for a threatened native fish

1. Predicting the ecological consequences of invasions by non‐native species is a fundamental aspect of their risk‐based management. As impacts can include the negative consequences of resource sharing with native species, the application of in situ cohabitation field experiments can test hypotheses relating to invasion ecology via competitive interactions and processes. As fishes are adaptable and tractable experimental organisms, they are strong model species for use in studies on competitive interactions.
2. The trophic consequences of invasion by two globally invasive freshwater fishes, common carp Cyprinus carpio and goldfish Carassius auratus, were tested on the threatened native fish crucian carp Carassius carassius. Cohabitation experiments, completed in pond enclosures, used all species in allopatric and sympatric treatments using a substitutive design where the number of fish per treatment was kept constant. Stable isotope analysis (δ¹³C and δ¹⁵N) assessed alterations in the trophic ecology of each species across treatments, with growth rates used to assess any consequent impacts on the fish.
3. When in sympatry with C. auratus and C. carassius, the Cy. carpio isotopic niche was at a significantly lower trophic position compared to allopatry. This resulted in niche overlap with C. auratus, while for C. carassius, their isotopic niche shifted to a higher trophic position compared with allopatry. The growth rate of Cy. carpio was always significantly higher in sympatry than in allopatry, whereas growth rates for C. carassius and C. auratus were significantly depressed in Cy. carpio presence. In contrast, the isotopic niche sizes and positions and growth rates of the Carassius fishes were not significantly different between allopatry and when they cohabited.
4. Plasticity in the isotopic niche of Cy. carpio resulted in significant alterations in their trophic position between allopatry and sympatry and, when coupled with their depressed growth in allopatry, suggests the competitive processes driving this were intra‐specific rather than inter‐specific. This then resulted in detrimental impacts on cohabiting Carassius fishes. These results emphasise that ecological consequences of Cy. carpio in invaded freshwaters include impacts on the trophic ecology of native fishes.

     

基于稳定同位素技术的三峡库区短颌鲚营养生态位特征研究

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δ¹⁵N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δ¹³C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,δ¹³C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¹⁵N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。     

三峡水库岛屿成岛前的植被特征与物种丰富度

三峡水库蓄水导致原有生境的岛屿化, 本文调查了三峡水库6个即将形成的岛屿蓄水前的植被特征, 并对这些岛屿上各类群落类型的物种丰富度进行了分析。共调查到群落类型28个, 其中草丛12个, 灌丛7个, 森林9个。研究结果表明, 绝大多数岛屿自然植被覆盖率低, 植被退化严重。主要表现为森林比重很小, 群落多样性低, 撂荒地上处于次生演替初始阶段的杂类草草丛占了相当大的比例。6个岛屿的植物种数分别为126、157、175、189、242、254; 其中森林群落的平均物种丰富度指数为42.19, 灌、草丛分别为15.96和17.89。杂类草草丛具有较高的丰富度指数, 而演替到较为稳定的退化草丛物种丰富度指数呈下降趋势。各类灌丛之间物种丰富度指数相差不大。在针阔混交林向阔叶林演替过程中, 物种丰富度指数表现为较大的波动性。由于自然植被被严重破坏, 岛屿上外来入侵种形成了较大的灾害。三峡库区即将形成的这些岛屿具有重要的研究价值, 建议选择一些岛屿建立保护区。     

三峡库区小江库湾鱼类食物网的稳定C、N同位素分析

应用稳定碳(δ₁₃C)、氮(δ₁₅N)同位素探讨了三峡库区一级支流小江库湾枯水期(2010.7)和丰水期间(2010.12)鱼类食物网结构。研究结果显示：初级生产者颗粒有机物(POM)和固着藻类δ₁₃C、δ₁₅N值范围分别为-23.33‰～-21.05‰、-25.13‰～-24.54‰,3.99‰～6.25‰、4.64‰～4.79‰。POM和固着藻类构成了小江库湾食物网能量的主要来源,其中丰水期间陆生营养物质输入是其食物网能量来源的一种重要补充途径。小江库湾常见鱼类食性可分为杂食偏植物食性、杂食偏动物食性及动物食性3种营养类群。在不同时期(枯水期和丰水期)小江库湾鱼类食物网营养级长度均有三级并且存在4种主要营养路径,表明了在三峡工程运行初期小江库湾已经形成了相对稳定的食物网结构。研究为小江库湾鱼类资源管理及生态系统恢复提供了一定的指导意义。     

三峡库区蓄水初期大宁河鱼类重金属污染特征

三峡水库蓄水后,库区不同水域的水体状态存在差异.为揭示三峡库区中不同水体环境条件对鱼类重金属含量的影响,以大宁河河口(巫山)和回水区(大昌)分别代表库区中的河流型和湖泊型水体,在两地分别采集了11种鱼类,利用稳定同位素分析了两地鱼类食物来源和营养等级,并测定鱼类样本中的Cr、Cd、As、Pb、Ni、Cu和Zn 7种重金属含量.结果显示,大昌鱼类的稳定同位素δ13C值范围(-28.8‰～-22.5‰)宽于巫山鱼类的δ13C值范围(-26.2‰～-23.1‰),但大昌鱼类的δ15N值普遍负于巫山鱼类.两地鱼体重金属含量除As外均处于较低水平.两地的中上层鱼类体内重金属含量无明显区别,但大昌的底层鱼类体内重金属含量显著高于采自巫山的底层鱼类含量,与沉积物的较多接触可能是该地区底层鱼类部分重金属水平显著升高的重要原因.     

Presence and absence of non‐native fish species in the Wet Tropics region,Australia

Distributional records of non‐native fish species were identified in the Wet Tropics region, Far North Queensland, Australia, through a compilation of published records and expert knowledge. A total of 1106 records were identified comprising 346 presence and four uncertain records for at least 13 species, and 756 absence records. All current presence records consist of six species from the families Cichlidae and Poeciliidae with established self‐sustaining populations in the region, probably affecting the highly diverse native fish fauna.     

三峡水库坝前段蓄水前后桡足类种类组成的变化

三峡水库蓄水后库区水环境发生了巨大变化,坝前茅坪至归州的西陵峡段由激流型河流生态系统演变为相对静水的水库型生态系统。桡足类是河流、湖泊、水库中重要的浮游动物类群,在水生态系统中占有重要地位,在浮游动物的研究中备受重视[1—7]。20世纪50年代三峡水库论证时也曾对其淹没区小水体的桡足类进行过调查,并对建库后的桡足类的种类组成进行了预测,但当时在未成库区干流中没有采集到桡足类[8]。作者对三峡水库蓄水前后坝前段(茅坪至归州)的桡足类进行研究,以期为三峡水库水生态系统中桡足类的演替、水环境管理、第二和第三阶段蓄水后桡…     

Altitude affects the distribution and abundance of two non‐native insect pests of the common walnut

The leaf miner Coptodisca lucifluella and the carpophagous Rhagoletis completa, of American origin, are two non‐native walnut (Juglans spp.) pests in Italy. For the Friuli Venezia Giulia region (FVG) (N‐E Italy), C. lucifluella is not yet listed, while R. completa has been present for over 25 years. During 2015, samples of leaves and fruits were collected from 219 single old common walnut trees (Juglans regia) placed at different altitudes (0–1,073 m a.s.l.) in FVG to detect the distribution and abundance of both pests. Samples of leaf miner larvae and their parasitoids were subjected to mitochondrial DNA analysis for identification. C. lucifluella has been found in 55 out of 219 sites. The species has been identified by typical leaf symptoms and by its DNA barcode. This is the first report of the species for FVG. The leaf miner distribution was negatively correlated with altitude. The species has not been observed at sites over 600 m a.s.l. Larvae were parasitized by native parasitoids identified as belonging to the genus Chrysocharis by morphological features and by DNA barcode. R. completa has been found in 89 out of 165 sites on walnut trees with fruits. The infestation level was very high in lowland localities. At sites over 700 m a.s.l., no infestation was found. Both species are widespread in the region, and their occurrence is significantly affected by altitude. Data suggest that walnut trees could be cultivated in some mountain areas without the need to control R. completa with insecticides.     

三峡库区消落带外来植物入侵与景观基质组成结构的关联性

外来物种入侵过程不仅受入侵地生境的影响,也受到周边景观基质的影响.厘清景观基质对外来入侵物种的影响,对于外来物种的入侵管控具有重要意义.本研究针对长江三峡库区消落带植物群落开展调查,评估三峡库区消落带外来植物入侵现状;在岸线以上(含消落带)2000 m范围内划分出10个景观格局尺度,采用14个指标分析景观基质组成结构;...     

Design of the dike-pond system in the littoral zone of a tributary in the Three Gorges Reservoir, China

The Three Gorges Dam is the greatest water control project in the world with the largest fresh water littoral zone. Emergence of the littoral zone during the growing season provides some plants with the opportunity to complete their growth cycle, but the fluctuating water level also brings about some environmental problems, such as soil erosion, water pollution, and biodiversity reduction. A series of cascading terraced ponds located in the littoral zone of a secondary branch of the Yangtze River at Laotudi Bay was designed to be a dike-pond system for resolving the environmental problems of this special littoral zone while also making use of resources in an eco-friendly manner. The design of the dike-pond system is described in detail in this article, and some monitoring protocols are recommended for evaluating the environmental benefits of the system. The economic value of the dike-ponds was estimated to be about ¥125,986. Due to the ecological management mode adopted, 14 species of wild aquatic plants and 6 species of wading birds were found in the dike-pond system, in contrast to 9 species of wild aquatic plants and 3 species of wading birds in a comparable conventional farming area. It is hoped that dike-pond ecological engineering will be instrumental in reducing water pollution and increasing biodiversity in the littoral zone of the Three Gorges Reservoir.     

三峡水库消落带外来植物组成及分布特征

[目的]探究三峡水库消落带外来植物的物种组成及分布特征,为库区外来植物管理防控、生物多样性保护和生态安全管理提供理论支持和数据参考。[方法]通过对库区消落带外来植物的实地调查,结合文献资料,研究外来植物的物种组成、原产地、引入途径、生活型及消落带外来植物的分布现状。[结果]三峡水库消落带存在66种外来植物,隶属于22个科50属,其中菊科、豆科、茄科和苋科是三峡水库消落带外来植物的优势科,共有40种,占总种数约60.6%,菊科的数目最多,达到21种;外来植物中来源于美洲的物种最多,达到66.7%;生活型以一年生草本植物居多;花果期多集中于5—10月份;外来植物中分布最为广泛的物种是大狼杷草、喜旱莲子草、鬼针草、钻叶紫菀、小蓬草和土荆芥;三峡水库内库首和库中区域消落带分布的外来植物较多。[结论]三峡水库消落带外来植物种类较多,分布广泛,在常年回水区外来植物入侵态势较为严重,入侵植物防控的形势不容乐观。建议结合消落带管理方法和消落带植物群落特征建立外来植物防治机制,积极采取相关措施,加强消落带外来植物扩散机制及其对本地生态系统影响的研究。     

Invasion by a non‐native ecosystem engineer alters distribution of a native predator

Aim

Shifts in diet composition, abundance or distribution of native predators can occur as a result of exotic prey introductions. We examined effects of non‐native earthworms and anthropogenic landscape disturbance on habitat selection by the American robin (Turdus migratorius), a generalist predator, at landscape and local levels. We also investigated whether robins could act as vectors of spread for earthworm cocoons (egg cases).

Location

Boreal forest of Alberta, Canada.

Methods

We conducted robin and earthworm surveys at campgrounds, well pads, roads, pipelines, seismic lines and forest interiors across northern Alberta. At a subset of paired locations that had similar habitats and anthropogenic disturbance levels, we sampled both robins and earthworms.

Results

Both groups were most likely to occur at campgrounds, well pads and roads. Furthermore, robins were more likely to occur at locations where earthworms were present in our paired local‐level surveys. This correlation between robin and earthworm distributions could be due to robins acting as a vector for earthworm spread, rather than robins’ use of earthworms as prey. However, in tests using captive robins, earthworm cocoons did not survive digestion.

Main conclusions

Robin and earthworm distributions were correlated, likely due to robins’ use of earthworms as prey. These results suggest exotic prey can strongly influence native predators at both landscape and local levels, with shifts in native predator distributions occurring as a result of spatial variability in exotic prey distributions. Although the impacts of ecosystem engineering by earthworms have been previously demonstrated, our study provides evidence that effects of earthworms can also cascade upwards via trophic interactions.     

三峡水库消落区不同海拔高度的植物群落多样性差异

本文对三峡水库消落区不同海拔间植物多样性和植物群落结构差异进行了研究。从α多样性上来看,上部和中部消落区物种丰富度和均匀度差异不显著,下部消落区丰富度指数明显低于中上部。下部消落区植物种间相遇几率较大,植物种间相互依存性较强。从β多样性上来看,由上部到中部再到下部,随着海拔下降,水库消落区植物物种的替代性减少是均质的;不同地区间β多样性没有显著性差异,但不同海拔间差异显著。从群落结构及稳定性上来看,目前水库消落区植物群落结构稳定性中部<上部<下部,上部消落区水淹胁迫较小,植物物种多为竞争种(C-对策种),竞争力较强的杂草偏向形成优势群落;下部消落区水淹胁迫最强,植物物种多为耐胁迫种(S-对策种),能忍受高强度水淹环境的物种形成了植物群落;中部消落区,处于物种定居和水淹胁迫的双重压力下,竞争种和耐胁迫种间竞争明显,更偏向于形成共优群落,其群落稳定性较差。在目前情况下,消落区下部的植物群落组成比较单一,但是随着水库蓄水高程稳定在175 m,估计消落区上中部群落组成也会逐渐趋于单一化。     

三峡库区水体中硫氧化菌的群落多样性

【目的】探究三峡库区干流和支流水体硫氧化菌群落组成和多样性及其与水体理化性质的相关性。【方法】于2017年3月在三峡库区支流和干流共选取9个采样点,测量各采样点水体理化参数,针对水体样品的sox B基因进行系统发育分析、聚类分析和多样性分析,并分析水体理化性质与硫氧化菌群落组成和多样性的相关性。【结果】克隆文库分析显示,本研究的三峡库区水体样品中硫氧化菌分属于α-Proteobacteria和β-Proteobacteria纲,其中β-Proteobacteria的硫氧化菌是群落构成主体,在干流和支流的采样点中相对丰度均高于95.6%。聚类分析和主坐标分析(PCo A)显示,各支流采样点之间以及支流样点和其对应干流样点之间的硫氧化菌群落构成差异较大,而干流采样点间硫氧化菌群落构成差异较小。Mantel检验结果显示,硫氧化菌群落组成与水体的温度、盐度、溶氧量、藻含量和p H等理化参数呈显著(P0.05)相关。Pearson相关性分析显示硫氧化菌的群落多样性与藻含量和DIC呈现显著负相关。【结论】三峡库区支流和干流水体中硫氧化菌主要由β-Proteobacteria纲构成,库区干流水体中硫氧化菌群落构成较为相似,而不同支流水体中的硫氧化菌群落构成差异较明显,并且支流和对应干流交汇处的水体中硫氧化菌群落组成差异明显,水体理化性质是导致这一差异的重要原因之一。     

淹水对三峡库区消落带香附子生长及光合特性的影响

为了阐明三峡库区消落带水位变化对香附子实生幼苗的影响,本研究模拟三峡库区消落带水淹环境,设置对照(CK)、根淹(T1)、半淹(T2)、全淹(T3)4个处理组,揭示香附子对库区消落带水位变化引起的不同水淹环境的光合生理响应机制。结果表明:经过45d的水淹后,所有处理香附子植株的基径、茎高和非光化学淬灭都有所增加,说明香附子植株对不同水淹环境都做出了积极的响应;植株叶长、叶宽及地上生物量在不同水淹环境中有不同的响应,与对照相比,半淹处理植株叶长、叶宽及地上生物量有所增加,而根淹、全淹处理植株叶长、叶宽及地上生物量有所下降;随着水淹时间的增加,所有水淹处理植株叶片比叶面积、净光合速率、气孔导度、蒸腾速率、最大光化学效率、电子传递速率以及光化学淬灭都显著低于对照,根淹和半淹植株虽有下降,但仍能保持较高的水平,而全淹植株则下降明显。研究表明,香附子能很好地适应水淹环境(尤其是部分水淹环境),未来可以应用于三峡库区消落带的植被重建,特别是针对长期遭受水位涨落的低海拔区域(145～160m),同时,香附子响应水淹的特性也为未来三峡库区消落带耐淹植物的筛选提供了依据。