星云湖枝角类群落变化的长期特征与驱动因素

以星云湖为代表的云南大中型湖泊近年来受到多个环境压力的胁迫,出现水质持续恶化、环境功能降低、生态系统退化等问题。目前针对这些湖泊生态环境的研究主要集中于以富营养化为代表的单一环境胁迫,且以短期监测为主,因此有效的湖泊治理与生态修复急需评价多重环境压力的长期驱动过程与特征。本文围绕星云湖枝角类群落沉积物记录,开展了多指标(如色素、粒度等)的综合分析,并结合湖泊调查、历史资料和多变量统计方法对主要环境压力与长期生态响应模式进行了识别。结果表明:沉积物分析中共鉴定出枝角类10属16种,其中盘肠溞属与象鼻溞属占绝对优势;在1890年之前湖泊沉积物色素浓度稳定在较低水平,随后湖泊生产力缓慢上升且沉积物颗粒(63μm)增加;1980年初开始沉积物色素含量快速上升,耐污种C.sphaericus明显增加并成为绝对优势种;随着湖泊生产力水平的上升,枝角类生物量持续增加(R2=0.753,P0.001,n=33),且枝角类群落出现显著变化(R2=0.953,P0.001,n=33);同时,随着外来鱼类的引入和鱼类捕食压力的变化,象鼻溞生物量总体下降但个体大小变化不明显;营养水平的持续增加与水生植物的逐渐消亡,可能导致了枝角类物种趋于单一,底栖枝角类生物量总体下降。总之,星云湖枝角类群落结构与生物量在过去100年来出现了显著变化,湖泊富营养化与生产力的变化是主要驱动因子,同时外来鱼类的引入、水文条件及水生植物的变化也对枝角类群落产生了重要的影响。     

高岚河大型底栖动物时空分布及影响因子研究

为了解大型底栖动物沿河流分布的物种丰富度变化及环境因子对其种群的影响,于2016年12月对高岚河的大型底栖动物进行了调查,并对理化指标进行了测定。研究结果发现,物种丰富度沿河流纵向梯度变化差异性不显著,生物多样性指数沿河流变化差异不显著,说明高岚河大型底栖动物群落结构稳定。高岚河上游的生态指示种为高翔蜉和四节蜉,中游的生态指示种为四节蜉和萝卜螺,下游的指示种为萝卜螺。模糊聚类分析发现高岚河大型底栖动物类群可划分为3个生境类群,且在梯度分布下群落生境较相似,大型底栖动物群落间关系接近,分布均匀。典范对应分析发现影响大型底栖动物群落结构沿梯度分布的主要因子是海拔、pH、浊度和深度。     

清潩河(许昌段)流域生物群落特征及其与环境因子的关系

以清潩河(许昌段)流域为研究对象,通过野外调查和室内测定,对水生植物、河岸带植物和大型底栖动物的群落特征、水体和表层沉积物的环境因子特征进行研究,分析清潩河流域内的生物多样性.结果表明: 流域内共有水生植物12种,河岸带植物66种,大型底栖动物10种.群落间环境因子变异较大,其中,水体的铵氮、总氮、总磷、表层沉积物的氧化还原电位、重金属镉、汞、锌的变异显著.典范对应分析表明: 水体理化性质如化学需氧量、温度、pH、溶解氧、总磷是影响水生植物的关键环境因子;水体氧化还原电位、pH和表层沉积物的镍、汞、有机质、铅、镉是影响河岸带植物分布的关键因子;表层沉积物的pH、温度、氧化还原电位、砷、铅、镍和水体温度是影响大型底栖动物的关键环境因子.清潩河(许昌段)流域水质污染严重,生物群落多样性低,沿河的污水处理及保护与恢复生物类群的工作迫在眉睫.     

河流岸带湿地沉积物重金属分布对植被物种多样性和底栖动物群落特征的影响

河流岸带湿地栖息地完整性对河流水环境、水生态和水文的安全与健康具有重要意义,为探究河流岸带湿地表层沉积物重金属分布特征及其对植被和底栖动物的影响,对滦河干流上中下游河段表层沉积物、植物群落和底栖动物调查分析,采用生物毒性效应系数法和综合潜在生态风险指数法评价沉积物重金属污染特征,采用植被物种多样性指数和底栖动物完整性指数评价滦河植物和底栖动物群落特征,探究岸带湿地沉积物重金属空间分布与植被及底栖动物群落特征之间关系。结果表明,滦河表层沉积物总体呈清洁水平,但不同河段重金属空间分布差异较大,下游重金属生态危害系数和潜在生态风险指数高于上中游。湿地物种调查共识别维管束植物219种,大型无脊椎底栖动物105种,综合评价结果表明下游植物群落物种多样性和底栖动物群落完整性低于上中游。滦河下游岸带湿地沉积物重金属对生物群落具有生物毒性和潜在的生态风险,降低了植被物种多样性和底栖动物群落完整性。大型底栖动物完整性指数能够综合反映底栖动物群落结构特征变化,对河岸带湿地生态健康评价和监测具有重要意义。     

安徽省石塘湖过去150年来枝角类亚化石记录及环境演化

近百年来长江中下游地区普遍经历了气候变化及日益增强的人类扰动,在多重环境压力胁迫下,该区众多湖泊的环境生态功能出现了明显变化。枝角类是水生生态系统的重要组成部分,且处于湖泊食物网的中间环节,敏感地响应于湖泊及其流域的环境变化,因此湖泊沉积物中枝角类亚化石具有重要的环境指示意义。本文通过对安徽省安庆市石塘湖沉积柱中枝角类亚化石序列的建立,结合当地的历史资料和监测数据,揭示了该湖百余年来的历史环境演变过程及驱动机制。研究结果表明,石塘湖枝角类群落长期以象鼻溞(Bosmina)占优,湖泊环境在1980年左右发生明显的状态转变,枝角类属种从附生圆形盘肠溞(Chydorussphaericus)及底栖属种龟状笔纹溞(Graptoleberistestudinaria)为主的组合向尖额溞(Alonaintermedia、Alonarectangular等)及简弧象鼻溞(Bosmina coregoni)的组合转变。1980年以前,自然环境条件为影响枝角类种群动态的主控因素,此后人类活动的影响越来越明显并最终成为枝角类种群动态的决定性因素。本研究揭示出浅水湖泊中枝角类亚化石对湖泊营养富集及人类活动扰...     

徐州城市河流和湖泊的大型底栖动物群落结构及影响因子分析

对徐州市京杭运河市区段和市区湖泊云龙湖进行了大型底栖动物群落结构及影响因子的比较研究。结果显示:城市河流和湖泊生态系统中, 大型底栖动物种类较少、群落结构相对简单, 其中城市河流大型底栖动物的组成主要为水栖寡毛类和软体动物, 城市湖泊大型底栖动物主要组成为水栖寡毛类和摇蚊幼虫。除Margalef 物种丰富度指数外, 河流与湖泊的其他群落指数相差不大。聚类分析将两类生态系统中的大型底栖动物群落明显分为两组。CCA 结果显示云龙湖大型底栖动物群落的主要影响因子是pH 和溶解氧, 京杭运河徐州市区段大型底栖动物群落的主要影响因子是总磷和化学需氧量。     

河口盐沼植物对大型底栖动物群落的影响

通过对长江口崇明东滩盐沼海三棱燕草带大型底栖无脊椎动物进行取样调查,研究了不同盐沼底栖动物群落结构及其多样性特征,分析了盐沼植物群落特征与底栖动物群落的关系。研究发现。（1）沿着河口盐沼海拔梯度,从低位盐沼到高位盐沼,底栖动物群落结构及多样性具有明显的梯度变化;（2）盐沼植被与底栖动物群落有密切的关系,尤其是植株高度,地下部分生物量与底栖动物密度,Shannon-Weiner多样性指数,物种丰度的相关性最显著。（3）盐沼植被影响底栖动物群落,是由于植物的地下部分和地下部分结构导致盐沼生境结构复杂,增加了沉积物表层环境的结构异质性,使生境多样化,给底栖动物提供大量生活空间,（4）不同盐沼带海三陵蔗草群落的差异,提供了盐沼表层地貌的变化,这种变化及植物结构的复杂化,在这一些动物提供拓殖地的同时,也为底栖动物躲避捕食者提供了避护所;（5）盐沼植被可以改变口潮滩生境中的沉积环境,并通过消浪、缓流及调节有机质的输入动态和沉积作用而影响底栖动物群落的组成和结构。     

云南高原湖泊沿岸带底栖藻类群落的分布

对云南6个高原湖泊沿岸带底栖藻类的群落结构、现存量等进行了调查,研究期间发现底栖藻类群落主要由绿藻门的刚毛藻(Cladophora spp.)和硅藻门的一些附植种类组成,除硅藻群落在泸沽湖占优势外,其它湖泊中绿藻群落的相对比率高于硅藻.底栖藻类现存量(chl a)以星云湖最高(24 μg·cm-2);底栖硅藻密度以泸沽湖的鸟岛最高,为9.3×106 cells·cm-2.分析不同湖泊底栖硅藻的群落结构发现:底栖硅藻Epithemia sorex和Cocconeis klamathensis分别是泸沽湖和抚仙湖的绝对优势种,Amphora pediculus是阳宗海和滇池金宝的绝对优势种,洱海、星云湖和滇池又一村的优势种类较多,其中相对丰富度较高的主要是一些附植性种类.结果表明沿岸带的光照、营养水平和基质类型可能是影响底栖藻类群落分布的主要环境因子.     

浴仙湖沉积物记录的云南极端干旱事件与生态响应评价

为评价湖库生态环境对极端气候的响应特征, 以经历水位明显降低的云南浴仙湖为研究对象, 通过沉积物多指标分析并结合多变量统计方法, 识别了2009—2013年极端干旱事件驱动湖泊生态环境变化的模式。其中沉积物粒度显示近百年来湖泊水文条件总体稳定, 但在2011年左右粗颗粒物质和中值粒径增大, 同期沉积物元素、同位素记录表明水体营养水平没有明显变化。硅藻群落近百年来以湖泊底栖物种占绝对优势, 约2011年开始优势种属Fragilaria被Nitzschia、Navicula等河流水体中常见的物种所替代, 且硅藻多样性指标总体增加, 而指示水位变化的PCA主轴一解释了硅藻群落结构的主要变化(约55.8%)。总之, 极端干旱事件的发生与持续明显改变了湖泊生物群落结构与多样性特征, 已成为影响该气候敏感区水资源安全与生态环境功能的重要挑战之一。     

雅砻江（锦屏段）及其主要支流底栖藻类群落与环境因子的关系

分别于2004年5月和11月对雅砻江(锦屏段)及其主要支流22个采样点的底栖藻类进行研究.共采获底栖藻类150种,分属3门(硅藻、绿藻和蓝藻),37属.其中硅藻门占绝对优势(96.5%),线性曲壳藻(Achnanthes linearis)和Achnanthes deflexa为绝对优势种,其相对丰富度分别为35.3%和11.0%.细端菱形藻(Nitzschia dissipata)和小型异极藻(Gomphonema parvulum)是雅砻江(锦屏段)干流的优势种,而线性曲壳藻、扁圆卵形藻(Cocconeis placentula)和Achnanthes deflexa是其他支流的优势种.基于底栖藻类的物种组成和相对丰度,对两次的采样点进行去势对应分析(DCA),结果发现:两次采样雅砻江(锦屏段)干流样点与其他支流样点在DCA第一轴上得到了很好的分化,表明研究区域底栖藻类群落存在明显的空间差异,这主要是由干流的特殊生境所致.典范对应分析(CCA)结果显示不同季节影响底栖藻类群落结构的环境因子有所差异.总磷(TP)是5月份影响底栖藻类空间分布的最主要因素;11月份影响底栖藻类空间分布的最主要环境因子为氨氮(NH4-N)和海拔(Elevation).     

Long‐term dynamics of a cladoceran community from an early stage of lake formation in Lake Fukami‐ike,Japan

An increase in nutrient levels due to eutrophication has considerable effects on lake ecosystems. Cladocerans are intermediate consumers in lake ecosystems; thus, they are influenced by both the bottom‐up and top‐down effects that occur as eutrophication progresses. The long‐term community succession of cladocerans and the effects cladocerans experience through the various eutrophication stages have rarely been investigated from the perspective of the early‐stage cladoceran community assemblage during lake formation. In our research, long‐term cladoceran community succession was examined via paleolimnological analysis in the currently eutrophic Lake Fukami‐ike, Japan. We measured the concentration of total phosphorus and phytoplankton pigments and counted cladoceran and other invertebrate subfossils in all layers of collected sediment cores, and then assessed changes in the factors controlling the cladoceran community over a 354‐year period from lake formation to the present. The cladoceran community consisted only of benthic taxa at the time of lake formation. When rapid eutrophication occurred and phytoplankton increased, the benthic community was replaced by a pelagic community. After further eutrophication, large Daphnia and high‐order consumers became established. The statistical analysis suggested that bottom‐up effects mainly controlled the cladoceran community in the lake''s early stages, and the importance of top‐down effects increased after eutrophication occurred. Total phosphorus and phytoplankton pigments had positive effects on pelagic Bosmina, leading to the replacement of the benthic cladoceran community by the pelagic one. In contrast, the taxa established posteutrophication were affected more by predators than by nutrient levels. A decrease in planktivorous fish possibly allowed large Daphnia to establish, and the subsequent increase in planktivorous fish reduced the body size of the cladoceran community.     

Patterns in the Distribution of Cladocerans (Crustacea: Branchiopoda) in Lakes Across a North–south Transect in Alaska, USA

The remains of cladocerans were examined from the surface sediments of 51 freshwater sites along a north–south transect spanning Alaska. We identified 27 cladoceran taxa from the sediments, consisting primarily of littoral chydorid species. Variations in cladoceran assemblages were related to measured physical and chemical variables using multivariate techniques. Redundancy analysis (RDA) indicated that lake depth, total phosphorus (TP), and altitude all had a significant influence in determining the composition of cladoceran assemblages. Cladoceran communities in tundra and forest-tundra lakes, which were relatively shallow and nutrient-poor, had relatively low abundances of pelagic Cladocera, and were primarily composed of several littoral chydorid species. Among pelagic cladoceran species, there was a distinct shift in dominance from the Bosminidae in lakes in the southern boreal forest region to Daphniidae in lakes in the northern boreal forest. Daphnia dominated lakes had significantly higher total phosphorus, specific conductivity, and calcium concentrations than lakes dominated by Eubosmina. Overall, the relative importance of physical and chemical factors in structuring cladocerans is similar to other previously studied regions, and suggests the Cladocera may be useful as ecological and paleoenvironmental indicators in this region.     

Rehabilitation of shallow lakes: time to adjust expectations?

We investigated the relative importance of flood defenses and other environmental variables for the cladoceran and copepod communities in floodplain water bodies in Southeastern Norway. The water bodies covered gradients of size, distance to the river and water chemistry, and half of them were located behind flood defenses. The effects of environmental variables on the communities were analyzed using redundancy analysis. The set of environmental variables accounted for more of the explained variation in the cladoceran community than in the copepod community. Water quality was much more important than flooding-related variables for both communities. Although cladoceran species richness was slightly higher in water bodies outside flood defenses, total nitrogen, total organic carbon (TOC), and water body area were the most important factors for the cladocerans. Macrophyte coverage was the most important variable for both species richness and community structure of copepods. Although our results show that water quality and spatial/structural variables are more important than flood defenses in structuring the communities, the effect of TOC on the cladoceran community could likely be mediated through effects of flood defense on TOC. Prospects for a continued anthropogenic pressure on river floodplains raise concern for the future of these unique ecosystems.     

Climate drivers of diatom distribution in shallow subarctic lakes

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The role of cladocerans in tracking long-term change in shallow lake trophic status

Shallow lakes have been affected by a variety of human activities profoundly altering their ecological structure and function. Cladocerans have been used to track change resulting from a variety of drivers at a number of time scales. Aquatic macrophytes are well recognised as reflecting the ecological condition of a lake. Here, we compare the plant macrofossils with the sub-fossil cladoceran assemblages from 20 dated sediment cores. Co-correspondence analysis was used to determine the degree of commonality of change in community composition of the two biological groups through time. This analysis revealed very high levels of agreement in the nature and timing of change at all the sites examined with very high correlation coefficients between the axis 1 scores for macrofossils and cladocerans. Furthermore, at all sites a high proportion of the variance (min 20%, max 54%) in the macrofossil data was explained by the change in the cladoceran assemblage. Sub-fossil macrofossil and cladoceran assemblages, from at least from 1700 AD onwards, were examined in more detail at three sites: Ormesby Great Broad, Felbrigg Lake and Lake Søbygaard. There was very good accord in the main shifts of the cladoceran and macrofossil assemblages at all three sites. This may reflect the long-term shift in the principal focus of primary production from the benthic to the pelagic habitat. We suggest that the combination of their central position in the food-web and the presence of both pelagic and benthic taxa make cladocerans a strong candidate as the single best indicator of (palaeo) ecological condition related to changing trophic status and alteration in food-web structure in shallow lakes.     

Subfossil Cladocera in relation to contemporary environmental variables in 54 Pan-European lakes

1. Changes in cladoceran subfossils in the surface sediments of 54 shallow lakes were studied along a European latitude gradient (36–68°N). Multivariate methods, such as regression trees and ordination, were applied to explore the relationships between cladoceran taxa distribution and contemporary environmental variables, with special focus on the impact of climate. 2. Multivariate regression tree analysis showed distinct differences in cladoceran community structure and lake characteristics along the latitude gradient, identifying three groups: (i) northern lakes characterised by low annual mean temperature, conductivity, nutrient concentrations and fish abundance, (ii) southern, macrophyte rich, warm water lakes with high conductivity and high fish abundance and (iii) Mid‐European lakes at intermediate latitudes with intermediate conductivities, trophic state and temperatures. 3. Large‐sized, pelagic species dominated a group of seven northern lakes with low conductivity, where acid‐tolerant species were also occasionally abundant. Small‐sized, benthic‐associated species dominated a group of five warm water lakes with high conductivity. Cladoceran communities generally showed low species‐specific preferences for habitat and environmental conditions in the Mid‐European group of lakes. Taxon richness was low in the southern‐most, high‐conductivity lakes as well as in the two northern‐most sub‐arctic lakes. 4. The proportion of cladoceran resting eggs relative to body shields was high in the northern lakes, and linearly (negatively) related to both temperature and Chl a, indicating that both cold climate (short growing season) and low food availability induce high ephippia production. 5. Latitude and, implicitly, temperature were strongly correlated with conductivity and nutrient concentrations, highlighting the difficulties of disentangling a direct climate signal from indirect effects of climate, such as changes in fish community structure and human‐related impacts, when a latitude gradient is used as a climate proxy. Future studies should focus on the interrelationships between latitude and gradients in nutrient concentration and conductivity.     

大理西湖流域开发历史与硅藻群落变化的模式识别

有关云南湖泊的研究长期集中于高原九大湖泊和水体富营养化评价,缺少对中小型水体及多重环境压力胁迫的综合研究.本文以大理西湖为例,结合沉积物记录与现代监测资料,甄别了气候变化和人类活动干扰下硅藻群落结构的长期响应模式及其驱动强度.结果表明: 20世纪50年代以前,大理西湖总体处于自然演化阶段;1950年代开始,围湖造田和流域改造的增强导致了水体营养水平增加、水动力条件改变,硅藻优势种由扁圆卵型藻替代为脆杆藻属;而1997年以来营养水平的快速增加和湖泊水动力的改变,促进了浮游藻类大量生长、底栖硅藻持续减少,同时水生植物快速退化、生态系统稳定性明显降低.因此,在长期流域开发的背景下,对云南中小型高山湖泊的有效保护需要评价流域开发类型、强度及全球变暖的长期影响.     

The relative significance of environmental and anthropogenic factors affecting zooplankton community structure in Southeast Wisconsin Till Plain lakes

Zooplankton community composition can be related to natural environmental factors such as lake morphology, lake landscape position, and water chemistry as well as anthropogenic factors such as agricultural and urban land-use. We hypothesized that within-lake factors, such as water chemistry, lake morphology, and human land-use would each be related to zooplankton community structure, but that watershed land-use would be the strongest correlate in southeast Wisconsin lakes. Zooplankton samples, collected every 3 months over a year, from 29 lakes were used to determine how lake and watershed morphology, water quality, and land-use were related to zooplankton community structure in the heavily developed Southeast Wisconsin Till Plain Ecoregion. Forward selection and a variation partitioning procedure were used to determine relative and shared contributions of each suite of variables in predicting zooplankton community structure. Redundancy analysis was used to characterize dominant gradients in pelagic zooplankton communities and related environmental factors and land-use. The major correlates of community structure included summer phosphorus, lake depth and surface area and urban and natural land. Variation partitioning illustrated that phosphorus alone accounts for the greatest part (12%) of community structure. Urban land-uses (residential, commercial and paved land) and lake morphology partially explain zooplankton community variation through combined effects with phosphorus. Small cladocerans and Skistodiaptomus pallidus were associated with higher phosphorus, shallow depth and higher urban land-use, while Daphnia pulicaria dominates in deep lakes with lower phosphorus and less urban land-use. This study contributes to the understanding of factors affecting zooplankton community structure in a largely human developed region and illustrates the importance of eutrophication in structuring zooplankton community composition.     

Environmental rather than spatial factors structure bacterioplankton communities in shallow lakes along a > 6000 km latitudinal gradient in South America

Metacommunity studies on lake bacterioplankton indicate the importance of environmental factors in structuring communities. Yet most of these studies cover relatively small spatial scales. We assessed the relative importance of environmental and spatial factors in shaping bacterioplankton communities across a > 6000 km latitudinal range, studying 48 shallow lowland lakes in the tropical, tropicali (isothermal subzone of the tropics) and tundra climate regions of South America using denaturing gradient gel electrophoresis. Bacterioplankton community composition (BCC) differed significantly across regions. Although a large fraction of the variation in BCC remained unexplained, the results supported a consistent significant contribution of local environmental variables and to a lesser extent spatial variables, irrespective of spatial scale. Upon correction for space, mainly biotic environmental factors significantly explained the variation in BCC. The abundance of pelagic cladocerans remained particularly significant, suggesting grazer effects on bacterioplankton communities in the studied lakes. These results confirm that bacterioplankton communities are predominantly structured by environmental factors, even over a large‐scale latitudinal gradient (6026 km), and stress the importance of including biotic variables in studies that aim to understand patterns in BCC.