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。     

Distribution and community structure of Ostracoda (Crustacea) in shallow waterbodies of southern Kenya

The current study presents the ostracod communities recovered from 26 shallow waterbodies in southern Kenya, combined with an ecological assessment of habitat characteristics. A total of 37 waterbodies were sampled in 2001 and 2003, ranging from small ephemeral pools to large permanent lakes along broad gradients in altitude (700–2 800 m) and salinity (37–67 200 µS cm^?1). Between 0 and 12 species were recorded per site. Lack of ostracods was associated with either hypersaline waters, or the presence of fish in fresh waters. Three of the 32 recovered ostracod taxa, Physocypria sp., Sarscypridopsis cf. elizabethae and Oncocypris mulleri, combined a wide distribution with frequent local dominance. Canonical correspondence analysis on species–environment relationships indicated that littoral vegetation, altitude, surface water temperature and pH best explain the variation in ostracod communities. Presence of fish and water depth also influence species occurrence, with the larger species being more common in shallow waterbodies lacking fish. Based on Chao’s estimator of total regional species richness, this survey recovered about two-thirds (60–68%) of the regional ostracod species pool. Scanning electron micrographs (SEM) of the valve morphology of 14 ostracod taxa are provided, in order to facilitate their application in biodiversity and water-quality assessments and in palaeoenvironmental reconstruction.     

Influence of fish assemblage and shallow lake productivity on waterfowl communities in the Boreal Transition Zone of western Canada

1. Shallow lakes in the Boreal Transition Zone (BTZ) in Alberta, Canada are naturally productive systems that provide important breeding and moulting habitat for many waterfowl (Anseriformes). To examine the relative importance of biotic and abiotic factors on waterfowl population densities, species richness and community composition, we surveyed 30 shallow lakes and evaluated the relationships among fish communities, lake characteristics and waterfowl in both breeding and moulting habitat. Shallow lakes were either fishless (n = 15), contained only small‐bodied fishes (n = 10) or contained large‐bodied, mostly predatory, fish in addition to small‐bodied fish (n = 5). 2. Environmental factors, including water colour, submerged aquatic vegetation, lake area and potassium, explained 24.3% of the variation in breeding waterfowl communities. Fish assemblage contributed independently to a small but significant proportion (13.4%) of the variation, while 13.8% of the explained variation was shared between environmental factors and fish assemblage. In total, 51.5% of the variation in breeding waterfowl communities was explained. 3. Overall, 55.5% of the total variation in moulting waterfowl communities was explained. Environment alone [especially total phosphorus, lake area, maximum depth and dissolved organic carbon (DOC)] and variation shared by fish and environment similarly accounted for most of the explained variation in moulting waterfowl communities (21.7% and 25.7% respectively), while fish assemblage was only one‐third as important (8.1%). 4. Both breeding and moulting waterfowl densities increased with lake productivity, even in eutrophic and hypereutrophic lakes. Breeding waterfowl density was also twice as great in fishless lakes than in lakes with fish, after accounting for lake area. 5. Certain waterfowl taxa were linked to fishless lakes, especially in the moulting season. Canvasback and moulting ring‐necked ducks were linked to small‐bodied fish lakes, whereas moulting common goldeneye were indicators of large‐bodied fish lakes. Knowledge of fish presence and species composition can therefore help guide conservation and management of waterfowl habitat in western Canada. Our results suggest that management efforts to maintain the most productive waterfowl habitat in the BTZ should focus on smaller, shallow, fishless lakes, particularly given that larger fish‐bearing systems have greater regulatory protection.     

中国重要生态系统保护和修复工程区域植被覆盖时空变化研究

植被覆盖变化是气候变化和生态环境变化的双重指示器,如何量化全国尺度植被变化、评估生态修复成效,成为当前陆地表层生态系统研究领域共同的科学问题。利用2000—2020年的植被覆盖度(FVC)数据,采用增幅变化分析、Theil-Sen Median趋势分析、稳定性分析方法,对中国六大重要生态系统保护和修复工程区域的自然植被覆盖度本底和时空变化特征进行了研究,并对不同区域植被覆盖度变化与气温、降水的相关性进行了分析,以期掌握我国生态系统保护和修复“家底”。结果表明：(1)2020年,六大区域平均植被覆盖度为27.66%,2000—2020年,黄河重点生态区、北方防沙带和青藏高原生态屏障区增幅分别为54.4%、34.6%和21.8%,是全国范围平均植被覆盖度增幅的1.04—2.59倍;长江重点生态区、东北森林带和南方丘陵山地带增幅分别为18.0%、13.7%和12.9%,均低于全国增幅,我国西北方较南方改善更明显。(2)2000—2020年,六大区域植被覆盖度变化总体呈增加趋势。黄河重点生态区、东北森林带、南方丘陵山地带和长江重点生态区增加区域面积占比均超过60%,北方防沙带和青藏高原生态屏障...     

鄱阳湖水生植被

本文列出了鄱阳湖98种水生维管束植物的名录,叙述了水生植被的分布。鄱阳湖水生植被面积为2262平方公里,占全湖总面积的80．8％。湖中植被呈不规则环带状分布,并可划分为湿生、挺水、浮叶和沉水4个植物带,9个主要植物群丛。并研究了鄱阳湖水生植被的演变及发展趋势和湖水位的季节性变化对植被的影响。     

Amphibian road mortality in Europe: a meta-analysis with new data from Poland

While the increasing vehicular traffic is widely suspected to play a role in the worldwide amphibian population decline, the research of amphibian road mortality is scarce, fragmented, fraught with methodological problems, and largely inconclusive. As the first attempt at a synthesis, we analyzed all available data on amphibian mortality in Europe and combined them with four previously unpublished surveys conducted by us. Based on our recalculation of road-kill counts in terms of species-specific road-kill recordability, we conclude that, in lowland Central Europe, the common toads, Bufo bufo, are the most common victims of vehicular traffic in suburban landscapes, while the common frogs, Rana temporaria and Triturus newts, prevail in rural landscapes. The green frogs also tend to be more frequent in rural areas. Common tree frogs, Hyla arborea, are unexpectedly rare in the road-kill record despite their terrestrial and migratory habits. In consideration of problems with obtaining accurate amphibian population estimates, we further propose the road kills-to-spawners ratio (R/S) as a working measure of the impact of road mortality on a local population. While the R/S ratio may not reflect the losses to an entire local amphibian population, it is free of the errors of whole-population estimates, which are notoriously difficult for amphibians. When corrected for species-specific road-kill recordability, most results suggest that the impact of roads on newts may have been underestimated and that the impact on common frog populations may be higher than on those of common toads. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users. Communicated by H. Kierdorf     

Ichthyofaunal assemblages in estuaries: A South African case study

This review places the life-history styles of fishes associated with South African estuaries in a global context and presents a classification system incorporating all the major life-history categories for estuary-associated fish species around the world. In addition, it documents the early life histories of the major fish groups in South African estuaries, with particular emphasis on the differing modes of estuarine utilization by marine, estuarine and freshwater taxa.This review details factors influencing the ichthyofaunal community structure in South African estuaries. The availability of fish for recruitment into an estuary depends primarily upon the distributional range of euryhaline marine and estuarine species, with tropical and temperate taxa showing marked abundance trends. Within a particular biogeographic region, however, estuarine type and prevailing salinity regime have a major influence on the detailed ichthyofaunal structure that develops. There is an increasing preponderance of marine fish taxa when moving from a freshwater-dominated towards a seawater-dominated type of system, and a decline in species diversity between subtropical estuaries in the north-east and cool temperate systems in the south-west. Similar declines in fish species diversity between tropical and temperate estuaries in other parts of the world are highlighted.Fish assemblages in estuaries adjust constantly in response to changing seasons, salinities, turbidities, etc. Despite persistent fluctuations in both the biotic and abiotic environment, the basic ichthyofaunal structure appears to have an underlying stability and to be predictable in terms of the response of individual species to specific conditions. This stability seems to be governed by factors such as the dominance of eurytopic taxa within estuarine assemblages and the robust nature of food webs within these systems. The predictability arises from factors such as the seasonality associated with estuarine spawning cycles and juvenile fish recruitment patterns. These patterns, together with a well-documented resilience to a wide range of physico-chemical and biotic perturbations, appear to be an underlying feature of fish assemblages in estuaries around the world.In contrast to marine fish species, estuary-associated taxa have received little conservation attention. Apart from the designation of protected areas, the main direct means of conserving estuary-associated fish stocks include habitat conservation and controls over fishing methods, effort, efficiency and seasonality. Of these, the conservation of fish habitats, the most important, because healthy aquatic environments invariably support healthy fish populations. The use of estuarine sanctuaries for fish conservation is briefly reviewed, as well as the legislation governing the USA National Estuarine Research Reserve System (NERRS) and the Australian Marine and Estuarine Protected Area (MEPA) system. It is concluded that South Africa requires an expansion of the existing Estuarine Protected Area (EPA) network, as well as the upgrading of selected 'estuarine reserves' where fishing is permitted, into 'estuarine sanctuaries' where no exploitation of biological resources is allowed.     

Habitat associations of pool-breeding amphibians in eastern Massachusetts,USA

There is a pressing need to develop a sound conservation strategy for pool-breeding amphibians, which includes gaining a better understanding of the habitat and landscape-scale characteristics associated with populations. To investigate relationships between amphibian species richness and characteristics of breeding pools and surrounding landscapes, we surveyed 85 pools in eastern Massachusetts (USA) in 1996 and 1997. A total of 11 species was detected, with most pools having 2–5 species. Pools were typically small, 77.6% were <0.2 ha, but most pools (72%) had hydroperiods that persisted at least into August in most years. Based on linear regression analyses, species richness was positively associated with three within-pool variables (pool surface area, hydroperiod, and the amount of emergent vegetation), and a landscape-level variable (presence of another breeding pool within 1 km), while one within-pool variable (tree canopy cover) exhibited a significant negative association with species richness. These within-pool habitat variables and connectivity to other breeding pools are important characteristics to consider when attempting to identify breeding sites that could provide core habitat in conservation reserves designed for the conservation of pool-breeding amphibian species richness. Conservation reserves for pool-breeding amphibian populations should include pool complexes functioning as habitat for metapopulations. Core pool habitats within such reserves should be large (0.5–1.0 ha), with seasonal hydroperiods that persist into August or that dry in some years, and with sufficient emergent vegetation to provide diverse microhabitats and refugia.     

Effects of Land Cover on Stream Ecosystems: Roles of Empirical Models and Scaling Issues

We built empirical models to estimate the effects of land cover on stream ecosystems in the mid-Atlantic region (USA) and to evaluate the spatial scales over which such models are most effective. Predictive variables included land cover in the watershed, in the streamside corridor, and near the study site, and the number and location of dams and point sources in the watershed. Response variables were annual nitrate flux; species richness of fish, benthic macroinvertebrates, and aquatic plants; and cover of aquatic plants and riparian vegetation. All data were taken from publicly available databases, mostly over the Internet. Land cover was significantly correlated with all ecological response variables. Modeled R² ranged from 0.07 to 0.5, but large data sets often allowed us to estimate with acceptable precision the regression coefficients that express the change in ecological conditions associated with a unit change in land cover. Dam- and point-source variables were ineffective at predicting ecological conditions in streams and rivers, probably because of inadequacies in the data sets. The spatial perspective (whole watershed, streamside corridor, or local) most effective at predicting ecological response variables varied across response variables, apparently in concord with the mechanisms that control each of these variables. We found some evidence that predictive power fell in very small watersheds (less than 1–10 km²), suggesting that the spatial arrangement of landscape patches may become critical at these small scales. Empirical models can replace, constrain, or be combined with more mechanistic models to understand the effects of land-cover change on stream ecosystems. Present address for L.C. Thompson: Wildlife, Fish and Conservation Biology Department, University of California, Davis, CA 95616.     

Repetitive changes in Early Pliocene vegetation revealed by high-resolution pollen analysis: revised cyclostratigraphy of southwestern Romania

A high-resolution pollen analysis has been carried out on the Lupoaia section (SW Romania) in order to check whether the repetitive clay–lignite alternations correspond to cyclic changes in climate. Increases in altitudinal tree pollen content appear to have been caused by drops in temperature, while developments of thermophilous elements correspond to rises in temperature, still under humid conditions. Such repeated changes in vegetation, on the whole consistent with the clay–lignite alternations, have been forced by cycles in eccentricity. On the basis of a comparison between the Lupoaia pollen record and (1) European climatostratigraphy (based on reference pollen diagrams documenting global changes), and (2) global climatic curves (eccentricity, δ¹⁸O), the age of the section has been reconsidered. The Lupoaia section (i.e. from lignite IV to lignite XIII) starts just before the C3n.3n Chron and probably ends just before the C3n.1n Chron. The section represents a time span of about 600 kyr, i.e. from about 4.90 Ma to about 4.30 Ma.     

Partitioning the diversity of riverine fish: the roles of habitat types and non-native species

1. Quantifying how biological diversity is distributed in the landscape is one of the central themes of conservation ecology. For this purpose, landscape classifications are being intensively used in conservation planning and biodiversity management, although there is still little information about their efficacy. 2. I used data from 158 running water sites in Hungary to examine the contribution of six a priori established habitat types to regional level diversity of fish assemblages. Three community measures [species richness, diversity (Shannon, Simpson indices), assemblage composition] were examined at two assemblage levels (entire assemblage, the native assemblage). The relative role of non‐native species was quantified to examine their contribution to patterns in diversity in this strongly human influenced landscape. 3. Additive diversity partitioning revealed the primary importance of beta diversity (i.e. among‐site factors) to patterns in species richness. Landscape‐scale patterns in species richness were best explained by between‐habitat type (beta₂: 41.2%), followed by within‐habitat type (beta₁: 37.7%) and finally within‐site (alpha: 21.1%) diversity. Diversity indices showed patterns different from species richness, indicating the importance of relative abundance distributions on the results. Exclusion of non‐natives from the analysis gave similar results to the entire‐assemblage level analysis. 4. Canonical analysis of principal coordinates, complemented with indicator species analysis justified the separation of fish assemblages among the habitat types, although classification error was high. Multivariate dispersion, a measure of compositional beta diversity, showed significant differences among the habitat types. Contrary to species diversity (i.e. richness, diversity indices), patterns in compositional diversity were strongly influenced by the exclusion of non‐natives from the analyses. 5. This study is the first to quantify how running water habitat types contribute to fish diversity at the landscape scale and how non‐native species influence this pattern. These results on riverine fish assemblages support the hypothesis that environmental variability (i.e. the diversity of habitat types) is an indication of biodiversity and can be used in large‐scale conservation designs. The study emphasises the joint application of additive diversity partitioning and multivariate statistics when exploring the contribution of landscape components to the overall biodiversity of the landscape mosaic.     

中国特有两栖类受胁现状分析

中国拥有丰富的两栖类资源,共321种,其中特有种236种,这些特有种是我国生物资源独特而重要的组成部分.但受人为和自然等因素的影响,中国特有两栖类出现了较快的种群数量下降,部分物种已经面临濒危状况而很少被人们关注.本文将对中国特有两栖类的数量、分布、受胁原因作简要阐述,以制定相应的保护对策.     

Unusual diel pHs in water as related to aquatic vegetation

High diel pHs (% MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGabmiwayaara% aaaa!36E2!\[\bar X\] > 9.0) showing little or no fluctuation were observed in several impoundments. This phenomenon was experimentally produced in water that contained only Myriophyllum spicatum or species of filamentous algae. Diel pHs ⩾ 9.0 were produced in the laboratory with as little as 0.2 g/1 of algae or vascular plants. The ability of these plants to cause high diel pHs in water may have evolved in response to competition with phytoplankton for carbon.     

Freshwater and wetland plant communities of Loch Lomond

Information on the aquatic and wetland vegetation of Loch Lomond, Scotland, is summarised for the period 1957–90. Aquatic macrophyte growth is estimated to occupy about 1% of the loch's total surface area, being limited to the 0–10 m euphotic zone, and probably excluded from much of this area by wave disturbance and unsuitable substrates. Aquatic vegetation is however abundant in sheltered bays and less-exposed shorelines, particularly in the South Basin of the loch. Although Littorella uniflora (L.) Aschers is the commonest, ubiquitous, submerged plant of the loch, three separate euhydrophyte communities have been identified within the loch. One of these is characterised by abundant stands of Elodea canadensis Michx., which appears to have invaded Loch Lomond some time between 1967–88, and has rapidly spread throughout the loch.