溪流大小及其空间位置对鱼类群落结构的影响

2008年10月和2009年10月分别对黄山地区阊江流域与青弋江流域1-3级浅水溪流中鱼类群落结构进行了研究,着重探讨了溪流大小及其空间位置对鱼类群落空间分布的影响。研究共捕获35种鱼类,阊江和青弋江分别为26和29种,其Jaccard相似性系数为57.1%;两流域间每样点的物种数差异显著,个体数差异极显著。在溪流级别梯度(1-3级)下,鱼类的物种数和个体数都呈上升的变动趋势,且物种数的变化相对个体数较显著。综合相关分析、逐步多元回归分析与典范相关分析的结果,阊江和青弋江中鱼类物种数的空间变化主要与下游量级相关,而个体数的空间变化主要与水宽相关。因此,阊江和青弋江1-3级浅水溪流中鱼类群落结构的空间分布格局是溪流大小和空间位置的共同作用结果,且溪流大小和空间位置分别决定鱼类的个体数与物种数的空间分布。     

湖泊阻隔对鱼类群落的影响——以保安湖为例

为探讨湖泊内部阻隔引发的生态问题, 阐释鱼类群落聚合对湖泊内部阻隔的响应, 研究选取长江中游典型阻隔湖泊保安湖为研究对象, 于2019—2020年夏季和秋季对其肖四海湖区(完全阻隔)、扁担塘湖区(半阻隔)、桥墩湖区(半阻隔)和主体湖区的鱼类群落结构进行了调查, 应用单因素方差分析、置换多元方差分析和非度量多维尺度等多重统计方法分析了湖区间鱼类群落组成和多样性的差异。结果表明, 完全阻隔湖区肖四海鱼类群落结构发生了明显变化, 其种类数[(15±3)种]显著低于半阻隔湖区[(22±3)种]和主体湖区[(23±3)种, P<0.05], 鱼类丰度高而生物量低, 物种丰富度指数、Shannon指数和Simpson指数显著低于主体湖区(P<0.05), 功能丰富度指数、功能分散度指数和功能均匀度指数也显著较低(P<0.05); 而半阻隔湖区鱼类群落结构与主体湖区无显著性差异。置换多元方差分析和非度量多维尺度分析也显示出完全阻隔湖区鱼类群落与半阻隔湖区和主体湖区鱼类群落具有显著性差异(P<0.05), 半阻隔湖区与主体湖区无显著性差异。研究发现湖泊内部水文阻隔对鱼类群落组成也有着重要影响, 恢复湖泊内部水文自由连通对湖泊生态管理和生物多样性保护有着重要作用。     

流溪河鱼类群落对水环境因子的响应及关键标识种的筛查

以处于亚热带地区的流溪河为研究对象,研究了流溪河鱼类群落结构特征及其与水环境因子的关系,并筛查了关键标识种。结果显示：调查期间共发现鱼类89种,隶属于8目23科70属,鲤形目（Cypriniformes）物种数量最多,其次是鲇形目（Siliuriformes）、鲈形目（Perciformes）。从源头至下游,流溪河鱼类多样性呈现先增加后降低的趋势,在中游干流河段最高,在下游受污染支流最低。典型对应性分析结果显示,流速、溶解氧、海拔、卵石底质、浅滩栖地是影响上游和支流河段鱼类分布的主要因子,COD_Mn、总磷、城市用地比例的增加则可能导致下游河段鱼类多样性降低。通过LEfSe方法筛选出能够反映不同生境断面鱼类群落特征的标识属/种34个,在此基础上,根据不同鱼种对食物来源和水环境栖息地的需求,优选了16个具有重要生态指示功能的标识种。这些标识种不仅能够指示特定的河流环境,还能反映当地食物网的完整性和健康状况,对维系水生态系统的结构和功能具有重要意义。     

城市发展对鱼类功能多样性的影响: 以超大城市北京为例

城市发展对当地的水生生态系统会造成不利影响。北京作为全球超大城市之一, 其城市化进程比大多数城市更为迅速, 因此北京水生生态系统受到城市发展的影响更甚, 尤其表现在对水生环境变化敏感的鱼类群体上。功能多样性是生物多样性的重要部分, 亦是评估生态系统功能的重要指标之一, 能更好地反映出鱼类群落中物种间资源分配和互补的程度。本研究结合野外调查数据、历史标本以及相关历史资料, 选取了与栖息、摄食、运动和繁殖4个方面相关的功能指标, 计算并比较了北京市1920-1960年、1960-1984年、1984-2013年和2013-2024年四个不同时期, 以及北京市建成区与生态涵养区的鱼类功能丰富度指数(FRic)、功能均匀度指数(FEve)、功能离散度指数(FDiv)和功能分散度指数(FDis), 探讨了城市化过程对北京鱼类群落的影响。研究表明, 北京市1920-1960年、1960-1984年、1984-2013年、2013-2024年分别记录到81、66、48、55种土著鱼类。北京四个时期的鱼类功能丰富度指数呈现先下降后上升的趋势, 从28.889先下降到17.693, 后又下降到11.358, 最后又回升到19.888, 这与四个时期的物种多样性变化同步, 而功能均匀度指数、功能离散度指数以及功能分散度指数变化很小。北京市建成区与生态涵养区的功能丰富度指数与两地区的物种多样性也呈正相关关系, 建成区的鱼类功能丰富度指数(1.639)明显低于生态涵养区(14.156), 而两地区的功能均匀度指数、功能离散度指数和功能分散度指数变化较小。总体而言, 功能丰富度指数对于城市发展变化的响应更为明显。北京市鱼类功能丰富度指数在2013年以前不断下降, 2013年以后有所回升, 这与土著鱼类资源得到了一定程度恢复, 且与一些外来鱼类占据部分缺失的土著鱼类生态位有关。外来物种防控应是北京作为超大城市在未来发展过程中需要特别注意的环节。     

罗霄山区生态用地时空演变及其生态系统服务功能的响应——以井冈山为例

生态用地的可持续利用对人类生存至关重要,而山区生态用地变化及其引起的资源环境效应是山区地域人地关系变化的反映,认识和探讨山区生态用地时空分布和形成机理对维持区域生态平衡和引导经济社会可持续发展具有深远意义。运用土地利用空间分析模型和Meta分析方法,分析井冈山的生态用地变化空间格局及其生态服务价值损益;利用Logistic回归和地理探测器,诊断生态用地的空间指向特征和时间演化过程。结果表明:(1)1990—2015年,井冈山生态用地变化显著,呈不断减少趋势,其中近城区表现最明显;生态用地转移的主要对象为城乡建设用地。1990—2000年间,井冈山生态用地的总体转移速率远远大于2000—2015年间的转移速率;林地的转移面积及占比最大,转移部分大于新增部分,属于生态用地减少型地类,而草地和水域属于生态增加型用地,且转移速率较大,是井冈山市较\"活跃\"的生态用地类型。(2)生态用地的时间演化过程的主导驱动因素包括人口数量和产业结构,空间演变格局中的主导驱动因素为到河流的距离和到地域中心的距离。(3)1990—2015年,生态系统服务价值不断降低但减少速率逐渐放缓,1990—2000年的年均减少量大于2000—2015年的年均减少量。其中,林地对生态服务价值的贡献最大。山区乡村振兴应以生态系统服务价值目标导向,实现农民生计和生态安全的协同优化,利用山区地域资源优势,强化三产融合,推进山区\"乡村振兴\"。     

外来养殖鱼类的入侵风险评估及防控对策——以尼罗罗非鱼为例

[目的]筛选合适的指标建立一套外来养殖鱼类的生物入侵风险评估体系,并对外来养殖鱼类的生物入侵防控提出对策建议。[方法]通过文献资料的收集和整理,对外来养殖鱼类中典型入侵物种的入侵过程、影响危害和入侵生物学特性进行分析和归纳,从适应能力、繁殖能力、扩散能力3方面指示其入侵性;从对生物的影响和对环境的影响2方面指示其生态影响;从自然因素和人为因素2方面指示环境可入侵性,以上述3方面为框架进行评估体系构建。[结果]筛选20个指标构建了外来养殖鱼类的生物入侵风险评估体系,并举例说明该评估体系的应用。从法规政策、科学研究、治理技术和公众参与等4个方面针对性地提出外来养殖鱼类生物入侵风险防控对策。[结论]防范和治理入侵生物是一个系统工程。对于外来养殖鱼类的管理,既不能只考虑经济效益而置生态风险于不顾,也不能片面放大外来养殖良种的入侵风险。科学管控的关键在于完善制度建设、加强风险评估、发展防治手段、促进公众参与,使外来鱼类养殖业在严格受控的前提下发挥其经济效益,将其潜在的生态危害效应降到最低。     

河流鱼类分类群和功能群的纵向梯度格局——以新安江流域为例

确定鱼类群落的空间格局是保护和管理河流鱼类多样性的基础。尽管河流鱼类分类群（基于物种组成）的纵向梯度格局已得到大量报道,但其功能群（基于功能特征）的空间格局研究较少。以皖南山区新安江为研究流域,沿其\"正源-下游\"梯度共设置27个调查样点,分别于2017年5月和10月完成2次调查取样,着重研究了鱼类分类群和功能群结构的纵向梯度格局及其形成机制。共采集鱼类44种,可分为5个运动功能群和4个营养功能群,构成14个\"营养-运动\"复合功能群。双因素交互相似性分析结果显示,鱼类分类群和功能群均随河流级别显著变化,但两者均无显著的季节变化;根据相似性百分比分析,由1级至3级河流,数量优势物种和功能群的空间变化主要呈嵌套格局,而由3级至5级河流其变化主要呈周转格局。方差分解结果显示,局域栖息地、陆地景观和支流空间位置3类解释变量对分类群和功能群空间变化的解释率分别为33.6%和38.5%,其中,分类群受局域栖息地和支流空间位置变量的显著影响,而功能群受局域栖息地和陆地景观变量的显著影响。研究表明,沿着新安江的\"上游-下游\"纵向梯度,鱼类分类群和功能群的空间格局基本一致,但两者的形成机制不同：分类群的纵向梯度变化受环境过滤和扩散过程的联合影响,而功能群则主要受环境过滤影响。     

城市化对鸟类群落组成及功能特征的影响——以京津冀地区为例

京津冀地区是中国经济发展的核心地区之一, 快速发展的城市化进程对生物多样性的作用与影响广受关注。鸟类是城市及市郊环境中分布最为广泛的野生动物类群之一, 对环境变化敏感, 是城市生物多样性的重要指示类群。本研究以京津冀地区鸟类为研究对象, 以“城市-乡村-郊野”分类体系图层为基础, 探究京津冀地区不同景观分区中鸟类多样性及其功能特征的差异。研究收集汇总来源于中国观鸟记录中心、GBIF数据库、ebird数据库等2000-2019年的鸟类实地观测数据58,620条, 筛选获得繁殖季(6-8月)和越冬季(12月至翌年2月)共计17,978条鸟类观测有效记录, 使用非度量多维尺度分析(non-metric multidimensional scaling, NMDS)、主成分分析(principal component analysis, PCA)、多元核密度估计(multivariate kernel density estimation)等方法, 分析不同分区内鸟类群落的物种组成与功能特征差异。研究结果显示, 京津冀地区2000-2019年共记录到鸟类482种, 分属于23目77科。经数据筛选后, 用于分析的总物种数为280种。其中, 乡村地区记录到的鸟类物种数最多(258种), 分属于20目64科, 占本研究京津冀地区记录鸟种总数的92.1%; 其次为城市(251种)和郊野地区(228种)。有70.7% (198种)的鸟种在3个分区中均有记录。就单个位点上鸟类局地群落的物种丰富度来看, 乡村和郊野地区均显著高于城市, 而乡村和郊野之间差异不显著。从物种组成来看, 城市、乡村和郊野3类分区的鸟类物种间存在较大重叠。不同分区下的鸟类功能特征分析结果显示: (1)城市和乡村局地群落内的鸟类体重均值显著高于郊野, 而城市和乡村之间无显著差异; (2)各分区之间鸟类的窝卵数没有明显区别; (3)城市中的鸟类多为广布种, 而郊野中的鸟类多为狭域种; (4)城市、乡村和郊野中鸟类物种整体上具有相似的食性特征。本研究揭示了生态良好、生境丰富的城市及周边环境能成为鸟类多样性的适宜载体, 城市化进程中伴随着鸟类对人类城乡景观的适应。对此, 我们建议持续探索高密度人口及高强度土地利用下的有效保护方式, 维持京津冀地区城市绿地公园、水域及湿地、乡村耕地等多类型野生动物栖息地的资源可用性。     

土壤纤毛虫群落对退耕还林生态恢复的响应——以侧柏林为例

为了了解土壤纤毛虫群落对退耕还林区生态恢复下土壤环境变化的响应及尝试利用土壤纤毛虫群落特征评价退耕还林生态恢复的效果,于2010年3月至9月采用\"非淹没培养皿法\"、活体观察法、蛋白银染色法和Foissner计数法对甘肃陇南武都退耕还林区5个不同恢复阶段的样点和1个荒草坡对照样点的土壤纤毛虫群落特征进行了研究,同时测定了p H值、温度、含水量及速效磷、有效钾、铵态氮、有机质和有机碳含量等土壤环境因子并分析了生态恢复条件下土壤纤毛虫群落特征与土壤环境因子的相关性。研究中共鉴定到71种纤毛虫,隶属于3纲、10目、22科、29属。研究发现,不同恢复年限的土样中土壤纤毛虫的物种分布存在明显差异,并随恢复时间的延长,样点间物种相似性减小,群落组成复杂化,物种数、种群密度和物种多样性指数总体均呈增长趋势。优势类群也发生了演替,由恢复初期的肾形目演替到后期的下毛目。相关性分析结果表明,在生态恢复条件下,土壤有机质和铵态氮含量是影响土壤纤毛虫群落结构稳定性的主要因素,不同纤毛虫类群对生态恢复的响应存在差异。冗余分析显示,土壤纤毛虫群落很好地响应了生态恢复过程中土壤环境条件的变化。     

水电开发对鱼类种群分布及生态类型变化的影响——以溪洛渡至向家坝河段为例

梯级水库修建后自然河流形成了河相段和湖相段,而河流生境的改变对鱼类种群空间分布和生态类型变化产生了重要影响。为探究金沙江梯级水电开发对鱼类资源的影响,结合2018年5月渔获物和文献记载水库修建前后的渔获物数据,分析了鱼类群落组成及变化,优势物种及群落多样性特点,以及鱼类在河相、湖相段生态类型的变化。结果表明,梯级水库建设后溪洛渡至向家坝鱼类的种类数减少,随着水库的运行该减少趋势放缓,而大型鱼的种类数占比呈增长趋势。受生境变化的影响,鱼类优势物种发生变化,水库河相段和湖相段生态类型差异较大。生态类型组成上以缓流型、生活于水流中下层、产卵初始水温高于18℃等生态类型占优。研究表明,高坝大库的运行会造成鱼类种群以生态需求为目标,形成明显的空间分布和群落结构特征,而梯级水库建设导致的水动力条件差异是鱼类群落生态类型差异的内在驱动力。     

EVOLUTION AND DEVELOPMENT OF BODY SIZE AND CELL SIZE IN DROSOPHILA MELANOGASTER IN RESPONSE TO TEMPERATURE

We examined the evolutionary and developmental responses of body size to temperature in Drosophila melanogaster, using replicated lines of flies that had been allowed to evolve for 5 yr at 25°C or at 16.5°C. Development and evolution at the lower temperature both resulted in higher thorax length and wing area. The evolutionary effect of temperature on wing area was entirely a consequence of an increase in cell area. The developmental response was mainly attributable to an increase in cell area, with a small effect on cell number in males. Given its similarity to the evolutionary response, the increase in body size and cell size resulting from development at low temperature may be a case of adaptive phenotypic plasticity. The pattern of plasticity did not evolve in response to temperature for any of the traits. The selective advantage of the evolutionary and developmental responses to temperature is obscure and remains a major challenge for future work.     

INFLUENCE OF FRESHWATER FLOW REGIME ON FISH ASSEMBLAGES IN THE GREAT FISH RIVER AND ESTUARY

Summary

Two and a half years of data were collected from the lower Great Fish River, head region and estuary to determine the fish species composition within these areas. Gilchristella aestuaria, Liza dumerilii, Rhabdosargus holubi and Pomadasys commersonnii were the four most abundant species captured, with riverine flow rate having an important effect on both species composition and numbers of fishes in the different regions. Most marine species displayed a strong inverse relationship between catch per unit effort and elevated freshwater inputs. Euryhaline marine species dominated the catches at all sampling sites during low flows but were less common during high flow periods when catadromous species were most abundant. Based on the available evidence it is suggested that for most marine species in the river this decline in abundance is related to low conductivity levels following floods rather than avoidance of elevated flows. The impact of elevated suspensoid concentrations and lowered dissolved oxygen concentrations on freshwater and estuarine fish populations during major river flooding is also discussed.     

THE STRUCTURE OF FISH GILLS IN RELATION TO THEIR RESPIRATORY FUNCTION

1. The general structure of the gills of different fishes is compared and it is concluded that, though essentially the same, there are certain differences by which they can be recognized. Possible ways in which they may have evolved from one another are considered. 2. A detailed account is given of the structure of the secondary lamellae, where gaseous exchange takes place, and it is shown that two epithelial sheets are separated by a vascular axis mainly composed of pillar cells overlain by a basement membrane on each side. Blood pathways through the gills are discussed in relation to their respiratory function. 3. The embryonic development of gills is described and evidence regarding homo-logies of different structures, particularly the pillar cells, is reviewed. 4. The gills of fish having different modes of life show variations in (a) the number of arches, (b) the number and length of the gill filaments, and (c) the size and frequency of the secondary lamellae. Ways in which measurements of gill area may be carried out and some of the complications involved are reviewed and a summary given of measurements made for a wide variety of species. Measurements of the thickness of the water-blood barrier are also discussed; the more active fish generally have thinner water-blood barriers and larger gill areas. 5. The different mechanisms of gill ventilation are summarized and characteristics of gill resistance in elasmobranchs and teleosts are compared. Gas exchange is discussed in relation to available techniques and the current terminology and symbols, and to indicate the value of analogies between gill exchangers and systems studied by engineers. 6. It is outlined how studies of the functioning of gills during coughing, parasitic infection, and in polluted waters add to knowledge of their role in respiration.     

THE BENTHIC MACROINVERTEBRATE FAUNA OF A SOUTH AFRICAN MOUNTAIN STREAM AND ITS RESPONSE TO FIRE

Summary

The effects of a late-summer prescribed burn on the temperature and benthic macroinvertebrate fauna of a south-western Cape mountain stream were investigated over a period of 12 months. Temperature and discharge regimes appear well-defined and relatively predictable from year to year. As in other mediterranean-type ecosystems, seasonal changes in the structure of the invertebrate community and the relative abundance of different feeding groups appear to be associated primarily with changes in the physical environment. Distinctive summer and winter communities were identified, with chironomids dominating the fauna in summer and simuliids dominant in winter. Although the riparian vegetation was only slightly damaged by the fire, a heavy, aseasonal leaf-fall occurred shortly afterwards. The canopy remained sparse for approximately four months. Stream temperature in the post-burn year was not demonstrably affected by increased exposure to solar radiation, however, probably because the canopy remained open during the winter months. The fire appeared to have little effect on the invertebrate fauna. Apart from five rare elements of the biota, all species recorded in the pre-burn year were present in the post-burn year and in similar densities. It is concluded that the riparian vegetation is of major importance in maintaining the integrity of the stream environment.     

A STUDY OF THE ORIENTATION OF THE SENSORY HAIRS OF THE RECEPTOR CELLS IN THE LATERAL LINE ORGAN OF FISH, WITH SPECIAL REFERENCE TO THE FUNCTION OF THE RECEPTORS

The morphology of the hair bundles on top of the receptor cells in the lateral line organ of the teleost fish Lota vulgaris is described. Each receptor cell shows a distinct morphological polarization. Two groups of receptor cells can be distingiushed, one consisting of cells polarized towards the head, the other consisting of cells polarized towards the tail. In the crista ampullaris all cells are polarized in the same direction. An hypothesis is proposed for the function of the receptor cells in the lateral line organ and the labyrinth based on a correlation of morphological and functional polarization.     

SPATIAL PATTERNS AND ECOLOGICAL DETERMINANTS OF BENTHIC ALGAL ASSEMBLAGES IN MID-ATLANTIC STREAMS, USA

We attempted to identify spatial patterns and determinants for benthic algal assemblages in Mid-Atlantic streams. Periphyton, water chemistry, stream physical habitat, riparian conditions, and land cover/use in watersheds were characterized at 89 randomly selected stream sites in the Mid-Atlantic region. Cluster analysis (TWINSPAN) partitioned all sites into six groups on the basis of diatom species composition. Stepwise discriminant function analysis indicated that these diatom groups can be best separated by watershed land cover/use (percentage forest cover), water temperature, and riparian conditions (riparian agricultural activities). However, the diatom-based stream classification did not correspond to Omernik's ecoregional classification. Algal biomass measured as chl a can be related to nutrients in habitats where other factors do not constrain accumulation. A regression tree model indicated that chl a concentrations in the Mid-Atlantic streams can be best predicted by conductivity, stream slope, total phosphorus, total nitrogen, and riparian canopy coverage. Our data suggest that broad spatial patterns of benthic diatom assemblages can be predicted both by coarse-scale factors, such as land cover/use in watersheds, and by site-specific factors, such as riparian conditions. However, algal biomass measured as chl a was less predictable using a simple regression approach. The regression tree model was effective for showing that ecological determinants of chl a were hierarchical in the Mid-Atlantic streams.     

中全新世以来大兴安岭中段红水泡泥炭地硅藻组合记录的古环境演化

本文提取大兴安岭中段红水泡泥炭地中晚全新世以来泥炭沉积中所含的硅藻化石,在82个样品中共发现32属94种硅藻。结合硅藻化石中优势种类生态特征,通过主成分分析发现,水位为控制该区域硅藻组合变化的最主要因素。其中,Meridion circulare,Meridion criculare var.constrictum等硅藻百分含量的升高指示水位的上升,Hantzschia amphioxys,Pinnularia spp.等硅藻百分含量的升高伴随水位的下降。根据主成分得分建立的红水泡泥炭地古水位曲线发现,中晚全新世以来当地气候经历了数次干湿交替变化,在总体上趋于干旱。其中5 000-3 300 cal a BP为相对湿润期,优势种类为M.circulare,M.criculare var.constrictum;3 300-1 900 cal a BP为气候转干期,H.amphioxys,C.meneghiniana,Pinnularia spp.成为该带中的优势种类;1 900-600 cal a BP,该段内红水泡泥炭地水位较上一阶段进一步下降,气候继续转干;600-200 cal a BP为气候转湿期,红水泡泥炭地水位迅速上升,Achnanthes lanceolata含量迅速增加成为该段优势种;200 cal a BP至今,红水泡泥炭地水位迅速下降,Pinnularia spp.成为该带中的绝对优势种。通过与季风区边缘其他研究区的古气候变化特征对比发现,红水泡泥炭地气候变化与多数研究区气候变化特征具有良好的一致性,因而推断其主要受东亚季风活动控制,泥炭沉积中硅藻化石组合记录可作为反映东亚季风变迁历史的良好指标。