黄河口潮间带沉积物细菌群落结构特征

选取黄河口潮间带有植被覆盖和无植被覆盖两个区域采集柱状沉积物,利用实时荧光定量PCR技术和高通量测序技术分析有无植被覆盖沉积物中的细菌群落特征和功能差异,探究影响潮间带细菌群落结构的主要环境因子。结果显示,细菌丰度在有植被区域大于无植被区域。沉积物中细菌群落丰富度和多样性在有植被区域随深度的增加而增加,而在无植被区域其最高值出现在沉积物中层（14-16 cm）。两个区域在门分类水平上以变形菌（Proteobacteria）、绿弯菌（Chloroflexi）、放线菌（Actinobacteria）和酸杆菌（Acidobacteria）为主;属分类水平上的优势类群为芽孢杆菌（Bacillus）、苍白杆菌（Ochrobactrum）、拟无枝菌酸菌（Amycolatopsis）和鞘脂单胞菌（Sphingomonas）等。相关性分析发现盐度和亚硝酸盐浓度对细菌群落多样性和丰富度影响显著。功能预测分析表明,有植被区域沉积物细菌在氨基酸代谢、膜运输和碳水化合物代谢方面功能活跃,而无植被区域细菌则在核酸复制和修复、能量代谢过程方面更为活跃。     

Spring and summer macroinvertebrate drift in the Lower Mississippi River,Louisiana

Macroinvertebrate drift was sampled dielly each month at three stations across the lower Mississippi River, Louisiana. At least 134 taxa were identified from seven phyla. Total drift catches varied with respect to month, time of day, and station. Relative abundance was greatest in June and August, moderate in July, and lowest in April and May. Dipterans, ephemeropterans and trichopterans numerically dominated the catches and each tended to have its zenith in July, August and June respectively. Important non-insect groups were hydroids, oligochaetes, pelecypods and amphipods and with the exception of pelecypods, were most abundant in April. The presence of certain apparent exotic oligochaetes suggested that at least some elements of the drift may be derived from rather remote areas — perhaps even the drainage headwaters. Diel periodicity was most pronounced during the summer months of high total drift densities. Ephemeropterans exhibited strong, nocturnally — oriented diel periodicity, both at the ordinal and lower taxonomic levels, trichopterans and dipterans showed varying tendencies with respect to individual lower taxa. Catches for the dielly-periodic taxa indicated a preponderance of the bigeminus forms. But each major insect order may have had one lower taxon exhibiting the alternans pattern. The stations were decreasingly productive from right-shore to left-shore, while taxonomic richness was greater at midstream and approximately equal along the shores. But spatial patterns of occurrence varied according to months.     

海河流域植被净初级生产力时空变化及驱动因素分析

为揭示海河流域植被净初级生产力(net primary productivity, NPP)时空变化特征及其时空异质性驱动机制，该文基于MOD17A3HGF数据集，综合自然和人为两方面的影响因素，利用变异系数、趋势分析、相关分析、Hurst指数以及地理探测器等，分析2000—2020年海河流域植被NPP时空格局演变特征和定量识别驱动因素及其影响力。结果表明：(1)时间上，2000—2020年海河流域植被NPP整体呈显著上升趋势，增速为1.73 Tg C·a^-1,年均NPP为326.75 g C·m^-2·a^-1,其中针叶林、阔叶林、灌丛、草地和农用地的NPP多年均值分别为313.59、385.28、353.03、320.12、295.22 g C·m^-2·a^-1。(2)空间上，植被NPP高值区集中于西北部山区，低值区集中于东南部平原区；NPP整体情况稳定，变异系数均值为0.17;未来变化趋势呈反持续性，植被NPP可能下降。(3)植被NPP与气温呈负相关，与降水呈正相关，降水为主要...     

鸭绿江口湿地外来入侵植物区系、生活型及种类特征

【目的】鸭绿江口湿地沿边沿海,生物入侵形势严峻,本文旨在探究其外来入侵植物特征的基本信息,为我国北方滨海湿地入侵植物防控提供支持和参考。【方法】基于植物地理学理论和外业实地踏查法,同时结合文献查阅和咨询法,研究鸭绿江口湿地外来入侵植物区系、生活型和种类特征。【结果】鸭绿江口湿地外来入侵植物共有33种,隶属11科26属,其中菊科、豆科和苋科是入侵植物的优势科,占总种数的57.57％;植物科的区系以世界分布型为主,属的区系以泛热带、世界分布型占主导地位;原产于美洲的种类最多,占总种数的51.52％;生长型以草本植物为主,占总种数的90.91％;生活型以地面芽和一年生植物种数最多,占总种数的87.87％;果实以瘦果类型居多,占总种数的27.27％;扩散方式以混合传播和风力传播为主,占63.63%;湿地内入侵植物危害等级以恶性入侵(Ⅰ级)和严重入侵种(Ⅱ级)为主,占总种数的39.4％。【结论】鸭绿江口湿地外来入侵植物种类以菊科、豆科和苋科为主;原产美洲最多,以草本植物为主,混合传播和风力传播占优,危害严重的种类多。应加强入侵植物监测和预警,并结合河口、海岸等生境治理,采取相应措施予以防除。     

赣江上游沉积物重金属空间分布及污染特征

为了解赣江上游表层沉积物重金属污染特征,采集赣江上游38个样品,采用电感耦合等离子体质谱仪(ICP-MS,Agilent 8800)分析沉积物中重金属含量,结合内梅罗综合污染指数法、地累积指数法、主成分分析及沉积物质量基准等研究赣江上游沉积物中重金属污染程度,分析污染物可能的来源及评价其存在的生态风险。结果表明:赣江上游沉积物中W、Cr、Mn、Cu、Zn、As、Cd、Hg、Pb等9种重金属的平均含量分别为12.30、4.40、999.84、9.72、293.81、47.66、2.85、1.34、63.68 mg·kg-1;除Cr和Cu外,其余7种重金属的平均值均超过江西省土壤背景值。内梅罗综合污染评价表明,赣江上游表层沉积物中47.37%的采样点呈严重污染,28.95%采样点污染明显,其中污染程度章水段>桃江段>贡江段;地积累指数法显示,Mn、As、W、Pb呈轻度污染,Cd和Hg呈中度或偏重度污染;主成分分析显示,As、W、Hg、Pb具有相似的污染源,Cr和Mn具有相似的污染源;沉积物质量基准分析表明,对底栖生物可能产生毒性效应的重金属主要是Cd和Hg,主要分布在章水段和桃...     

Assessing the efficiency of connectivity measures with regard to the EU-Water Framework Directive in a Danube-tributary system

The effect of restoring connectivity for fish by the construction of 11 fish ladders in the Pielach and Melk rivers, both tributaries to the Danube in Austria, was monitored using electric fishing and fish traps between 1999 and 2004. In order to assess the efficiency of connectivity rehabilitation measures pre- and post-project data combining electric fishing and trap catch data were analyzed by means of three fish-based assessment methods: a MUlti-Level concept for a Fish-based, river-type-specific Assessment of ecological integrity (MULFA), the Fish Index Austria (FIA) and the European Fish Index (EFI). The effect of adding qualitative trap catch data to electric fishing data on metrics and indices was also tested and the magnitude of the effect was related to the distance of the sites from the river mouth. The results clearly demonstrated the significant contribution of connectivity rehabilitation measures to the ecological integrity of rivers like the River Pielach where morphological conditions are good, whereas remaining channelization still limits the success of connectivity measures in the River Melk. Trap catch data were found to represent an essential source of additional information to assess the efficiency of connectivity measures shortly after their implementation. The negative correlations of the magnitude of the effect of different indices and metrics with the distance of assessment sites from river mouths obviously underline the importance of the river Danube as a source for the re-colonization process. While the indices tested were found to have limited ability to reflect short-term response of fish assemblages to continuum rehabilitation, guild metrics were able to detect improvements of the ecological status shortly after the implementation of connectivity measures. Six metrics showed significant differences between pre and post-project data reflecting the expected increase of the ecological integrity: (1) Fish Region Index (FRI; FIA, MULFA), (2) number of subdominant species and (3) number of flow-guilds (FIA), (4) number of type specific species (MULFA), (5) number of benthic species and (6) number of potamodromous species (EFI); the FRI differences were only significant when trap catch data were added. The EFI indicated a decline of ecological integrity through increases in the density of omnivorous species and the relative number of tolerant species as well as a decrease in the relative number of intolerant species. Significantly decreasing responses with the distance from the river mouth were documented by the EFI and MULFA-index, the FRI (FIA, MULFA), total biomass and for the number of type specific species (MULFA). Guest editors: R. L. Welcomme & G. Marmulla Hydropower, Flood Control and Water Abstraction: Implications for Fish and Fisheries     

Indicators of movement and space use for two co-occurring invasive crayfish species

Red swamp crayfish (Procambarus clarkii) and signal crayfish (Pacifastacus leniusculus) are two invasive freshwater species with a worldwide distribution. The objective of this work was to investigate how the two species move and use space in an area of recent coexistence. Simultaneously, we test the use of new tools and indices to describe their movement patterns. To accomplish this we performed a radio-tracking program within a river-type habitat during two different periods (September/October 2010 and June/July 2013). We used spatial analysis tools to map crayfish radio-location data with and without accounting for the curvature of the river. To assess the consistency of the direction of movement and of the distances traveled by crayfish, two indices were developed. To assess the habitat preferences of each species we applied Ivlev's Electivity Index and the Standardized Forage Ratio. Movement of P. clarkii and P. leniusculus differed. The average detected movement was 8.8 m day⁻¹ for P. clarkii and 17.5 m day⁻¹ for P. leniusculus. However, crayfish behavior ranged from almost complete immobility – sometimes during several days – to large movements, in half a day, up to a maximum of 255 m for P. clarkii and 461 m for P. leniusculus. The proportion of upstream or downstream movements was independent of the species and both species displayed no preference for either direction. The indices of consistency of movement showed a large interindividual variation. Species and period (2010 or 2013) affected the mean daily distance traveled, maximum observed distance from location of release and percentage of observations under vegetation cover. The Ivlev's Electivity Index and the Standardized Forage Ratio presented similar results. P. clarkii showed a preference for pool areas with riparian vegetation cover while P. leniusculus preferred riffle and pool areas with riparian vegetation cover. Our work provided new and valuable data for modeling the active dispersal of these two problematic invaders in a context of coexistence.     

黄河流域景观破碎化时空特征及其成因探测

黄河流域快速的人口增长和城市扩张加剧了土地利用转型和生态景观破碎化,引发了诸如生态系统功能退化、生物多样性功能减弱以及生境破碎化等一系列严重问题。探明黄河流域景观破碎化时空特征及其成因对维护流域生态系统稳定和生态修复具有重要指导意义。但是以往研究缺乏对黄河流域景观破碎化时空特征及其归因分析的相关研究,难以为黄河流域生态环境治理以及景观格局优化提供科学指导。基于FRAGSTATS4.2软件测度了2000—2018年黄河流域县域单元景观破碎化时空格局特征,并借助地理探测器模型探讨了黄河流域景观破碎化时空分异的成因。研究表明：(1)研究期间黄河流域斑块密度(PD)无显著变化,边缘密度(ED)、景观形状指数(LSI)、平均斑块面积(Area＿AM)均呈先增后减的变化趋势,聚集度指数(AI)呈先减后增的趋势;蔓延度指数(CONTAG)持续降低,分离度(DIVISION)、香农多样性指数(SHDI)逐年增高。(2)研究期间黄河流域景观破碎化程度总体逐渐加剧,流域中下游各省破碎化程度变化剧烈,上游各省破碎化程度变化趋于平稳。(3)地理探测器结果显示,黄河流域景观破碎化受到自然、社会等多重因素影响,因...