一种动态生态环境需水计算方法及其应用

随着经济的发展,我国的水资源形势日趋严峻,河流生态环境问题日渐突出.生态环境需水是影响河流生态系统健康的重要因素,生态环境需水量的界定、计算和分析是水资源管理中实现人与自然和谐发展的重要途径.针对传统生态环境需水计算方法实用性和可操作性差的缺点,开发出动态生态环境需水计算方法,利用月保证率法计算出初始生态环境需水状态空间,再根据实际的水资源开发利用形势,将自然因素和社会因素综合考虑,形成生态环境需水量的状态空间,然后用改进的水文指数法评价各生态环境需水状态,使生态环境需水的计算由静态变为动态.将该方法应用于水量年内分配不均,时有断流现象发生的年楚河,计算出了9个具有可操作性的生态需水状态,根据当地的实际情况,建议水资源管理部门以状态3和状态4为近期水资源管理的目标.     

河流生态径流计算的逐月频率计算法

界定了生态径流、最小生态径流、最大生态径流、适宜生态径流的概念,提出了一种新的河流生态径流计算方法——逐月频率计算法,指出了方法的优缺点以及适用范围。以计算洛阳市境内伊河的栾川站和龙门镇站生态径流为例,说明了计算过程,同时用Tennant法作对比。结果表明:运用新的逐月频率计算法比用以往的逐月频率计算法得到的适宜生态径流过程径流量要大,河流的生态状况更好,更有利于河流自身的生态健康和河流周围生物栖息地的保护。     

Factors determining length distribution and abundance of the European eel, Anguilla anguilla, in the River Mondego (Portugal)

1. The distribution and abundance of the European eel, Anguilla anguilla, were investigated in the Mondego River, a strongly modified river in central Portugal. Nine freshwater sites, located below the first impassable obstacle to eel migration, were surveyed for 2 years. The study was conducted monthly during the first year and seasonally during the second year. Fish were caught by electric fishing and, physical and biotic variables potentially influencing eel length distribution and abundance were determined at each sampling session. 2. Canonical correspondence analysis (CCA) was used to explain the relationships between abiotic and biotic habitat variables, and eel length distribution. Spatial variation was strongly associated with distance from the sea, number of obstacles, river width and percentage of instream cover. Depth, river flow, water temperature and cannibalism had weaker effects on the longitudinal distribution, but contributed as explanatory variables for the model. The influence of spatial variables outweighed the importance of temporal variables as predictors in this model. 3. Length distribution changed in space from a dominance of small eels (<100 mm) closer to the sea to larger eels (≥250 mm) in the upper reaches of the river. The smallest length class (eels <100 mm) was strongly associated with wider stretches where instream cover, mainly composed of aquatic submerged macrophytes, was abundant (>75% area coverage). On the contrary, larger eels (≥250 mm) preferred deeper stretches with stronger river flow and less instream cover. 4. The effect of biotic interactions with conspecifics as well as with the non‐native red swamp crayfish Procambarus clarkii, in sites with poor instream cover, modified this general pattern of distribution leading to fewer eels <100 mm at some sites closer to the sea. Therefore, despite the ubiquity and plasticity shown by this species, there were clear ontogenetic variations in habitat use such that the first two canonical axes of a CCA accounted for 58.4% of the spatial variability in size structure.     

A qualitative procedure for the assessment of the habitat integrity status of the Luvuvhu River (Limpopo system,South Africa)

The riparian zone and instream habitat integrity of the Luvuvhu River were assessed based on a qualitative rating of the impacts of major disturbance factors such as water abstraction, flow regulation, bed and channel modification, etc. A system was devised to assess the impact of these factors on the relative frequency and variability of habitats on a spatial and temporal scale gauged against habitat characteristics that could have been expected to occur under conditions not anthropogenically influenced. It was found that deterioration of habitat integrity can be ascribed primarily to water abstraction. This has resulted in the cessation of surface flow in a naturally perennial river during the dry season and during droughts with consequent tree deaths and a loss of fast flowing instream habitat types in the main stem of the river. The relatively small high rainfall area in the catchment, the highly variable rainfall pattern and the occurrence of sporadic severe droughts exacerbate the impact of water abstraction on the instream and riparian habitats with expected detrimental consequences for the associated biota. The effect of water abstraction is particularly severe in the lower part of the river which flows through the Kruger National Park as no perennial tributaries join the Luvuvhu River in this section. Other factors which affect the habitat integrity of the river are the removal of indigenous riparian vegetation in some river sections, encroachment by exotic vegetation, bank erosion and stream bed modification.     

Fish habitat modelling as a tool for river management

This paper presents an integrated modelling approach to simulate and assess ecological effects of physical habitat changes in rivers. An ecohydraulic simulation tool was created by combining a 1D hydraulic model based on HEC-RAS software and the fish habitat module of CASiMiR, a fuzzy logic-based ecohydraulic modelling system. This tool was applied on a river stretch commonly occurring in Belgium and elsewhere in Europe. In particular the effect of weir removal on habitat suitability for bullhead (Cottus gobio L.) was simulated. Physical conditions of the studied stretch after weir removal were simulated with a hydraulic model. CASiMiR linked these conditions to ecological expert knowledge to calculate habitat suitability for three life stages of bullhead at four different flow rates based on fuzzy logic. Results indicated that after weir removal, habitat suitability increased significantly for all life stages and all flow rates. The presented approach is promising regarding fish community assessment and ecological river engineering.     

Habitat‐specific invertebrate responses to hydrological variability,anthropogenic flow alterations,and hydraulic conditions

相似文献   

Assessment of spatial habitat heterogeneity by coupling data-driven habitat suitability models with a 2D hydrodynamic model in small-scale streams

Habitat assessment considering habitat quality and quantity is a key approach in conservation and restoration works for biodiversity and ecosystems. In this regard, application of hydrodynamic model for modeling instream habitat conditions and machine learning (ML) methods for modeling habitat suitability of a target species can contribute to better modeling practices in ecohydraulics. Despite the importance of small streams for aquatic ecosystems, previous studies in ecohydraulics have been conducted mainly in medium to large rivers, often disregarding small-scale streams such as agricultural canals. The aim of this study is to demonstrate the applicability of a coupled use of ML and a two-dimensional (2D) hydrodynamic model for assessing spatial habitat heterogeneity in small-scale agricultural canals in Japan. Using abundance data of Japanese medaka (Oryzias latipes), four ML methods, namely artificial neural networks (ANNs), classification and regression trees (CARTs), random forests (RF) and support vector machines (SVMs), were applied to develop habitat suitability models considering water depth and flow velocity. A 2D hydrodynamic model was developed based on field surveys in two types of agricultural canals, namely earthen and concrete-lined canals. Information entropy was used for assessing the spatial heterogeneity of instream habitat conditions. As a result, the hydrodynamic models could model instream habitat conditions in a reasonable accuracy. Despite the differences in accuracies in habitat modeling, the four ML methods illustrated similar habitat suitability information for Japanese medaka. The coupled ecohydraulics modeling approach could quantify habitat quality and its spatial heterogeneity, based on which the differences between the earthen and concrete-lined canals were quantitatively assessed. This study demonstrated the applicability of ML-based habitat suitability evaluation and a 2D hydrodynamic model for modeling the spatial distribution of habitat suitability and assessing its spatial heterogeneity. Further study, assessing the spatial heterogeneity in various types of flows including natural/artificial and small/large streams, can contribute to establish quantitative criteria for an ecologically sound habitat and improved ecofriendly construction works in small-scale rivers and streams.     

On the use of climate covariates in aquatic species distribution models: are we at risk of throwing out the baby with the bath water?

Species distribution models (SDMs) in river ecosystems can incorporate climate information by using air temperature and precipitation as surrogate measures of instream conditions or by using independent models of water temperature and hydrology to link climate to instream habitat. The latter approach is preferable but constrained by the logistical burden of developing water temperature and hydrology models. We therefore assessed whether regional scale, freshwater SDM predictions are fundamentally different when climate data versus instream temperature and hydrology are used as covariates. Maximum entropy (MaxEnt) SDMs were built for 15 freshwater fishes using one of two covariate sets: 1) air temperature and precipitation (climate variables) in combination with physical habitat variables; or 2) water temperature, hydrology (instream variables) and physical habitat. Three procedures were then used to compare results from climate vs instream models. First, equivalence tests assessed average pairwise differences (site‐specific comparisons throughout each species’ range) among climate and instream models. Second, ‘congruence’ tests determined how often the same stream segments were assigned high habitat suitability by climate and instream models. Third, Schoener's D and Warren's I niche overlap statistics quantified range‐wide similarity in predicted habitat suitability from climate vs instream models. Equivalence tests revealed small, pairwise differences in habitat suitability between climate and instream models (mean pairwise differences in MaxEnt raw scores for all species < 3 × 10^–4). Congruence tests showed a strong tendency for climate and instream models to predict high habitat suitability at the same stream segments (median congruence = 68%). D and I statistics reflected a high margin of overlap among climate and instream models (median D = 0.78, median I = 0.96). Overall, we found little support for the hypothesis that SDM predictions are fundamentally different when climate versus instream covariates are used to model fish species’ distributions at the scale of the Columbia Basin.     

河流微生境异质性与大型底栖动物空间分布的关系

大型底栖动物是河流生态系统较好的指示类群,越来越广泛地应用于河流生态状况评价.识别大型底栖动物空间分布的影响因素可以分为宏观尺度因子、中观尺度因子和微观尺度因子.前人的研究较多集中于中观尺度.本研究基于10 m河段微生境因子与大型底栖动物调查,采用地统计学方法,在微观尺度上分析了大型底栖动物空间分布特征及其与微生境的关系.结果表明:不同生境类型中底栖动物指标存在差异性,激流、深潭和急流的Shannon指数平均值分别为2、1.9、1.78;大型底栖动物密度、生物量、丰富度指数及Shannon指数具有空间自相关性,存在一定的扩散效应;微生境因子与大型底栖动物指标及物种的空间关系存在差异性,其中,水深和流速与大型底栖动物关系的拟合度较弱,底质组成与大型底栖动物的拟合关系相对较好,底栖动物密度与粒径<4 mm底质体积百分比呈现正空间自相关,生物量、丰富度指数、Shannon指数与粒径>32 mm底质体积百分比呈现正空间自相关.本研究结果可为底栖动物扩散机制研究、调查样方设置、物理生境修复等提供参考.     

Microhabitat preferences of benthic fauna in a woodland stream

Estimates of numbers, biomass, and diversity of benthic macroinvertebrates were made quarterly over a two-year period to investigate microhabitat preferences. Although biomass of most taxa was significantly different among sampling times, physical factors also appeared to be important in determining abundance of many taxa. Optimum depth, velocity, substrate type, and turbulence were determined for major taxa. Optimum conditions for diversity appeared to be 34 cm depth, 60 cm s^?1 velocity, and rubble and boulder substrate type. Habitat preference functions were derived for several taxa based on significant polynomial regressions of biomass on depth, velocity, substrate, and Froude number (turbulence). The relationship between abundance and physical habitat conditions was tested by using the product of the preference factors (range: 0–1) for depth, velocity and substrate type as a measure of habitat suitability (joint preference factor). There were significant correlations between biomass [transformed by log_e (x + 1)] of 10 benthic species and the joint preference factor. The joint preference factors accounted for from 11 to 61% of the variation of biomass of the 10 benthic species. The intercepts of the relationships between biomass of individual species and the joint preference factor were not significantly different from zero for any species. Therefore, the joint preference factors appear to be valid indicators of biomass. The preference functions have utility in habitat assessment studies, specifically with regard to minimum instream flow determinations.     

Linking microhabitat availability and local density of rainbow trout in low-gradient Japanese streams

Quantification of reach-based microhabitat availability for rainbow trout (Oncorhynchus mykiss), considering their microhabitat requirements in two low-gradient streams, northern Japan, was attempted to test for habitat space limitation of local trout density. Underwater observations revealed that fish selected microhabitats of moderate current velocity, relatively greater depth and shorter distance to overhead cover in both streams, although habitat features used and available differed slightly between the streams. Habitat space for fish potentially available in the channel environment was evaluated using principal component analysis (PCA) of both available and used microhabitat. A close relationship was evident in both streams between reach-based microhabitat availability and fish density, which was assessed by a three-pass removal method. Direct estimates of fish microhabitat availability using PCA can contribute to accurate predictions of local fish density and provide insight into the mechanisms responsible for fish–habitat relationships in streams.     

Fish habitat rehabilitation using wood in the world

To provide river managers and researchers with practical knowledge about fish rehabilitation, various studies of fish habitat rehabilitation that used wood were reviewed. The review focuses on fish responses, wood installation methods, and geomorphic features of the rehabilitation sites. Most studies were conducted in moderately sized (small and medium) streams with relatively high bed gradients and aimed to improve the habitats of salmonid species. In this stream type, structures spanning the full (log dam) and partial (log deflector) width of the river were most common, and wood structures that created pools and covers were successful in improving fish habitat. Some projects were conducted in moderately sized low-gradient streams, in which wooden devices used to create instream cover were effective for fish assemblages. There were few studies in other aquatic ecosystems. However, well-designed large wood structures, known as engineered log jams, were used in rehabilitation projects for large rivers. In slack-water or lentic systems such as side-channels, estuaries, and reservoirs, small and large wood structures that created cover were used to improve habitat for many fish species. For successful fish habitat rehabilitation projects, the hydrogeomorphic conditions of rehabilitation sites should be carefully examined to avoid physical failure of wood structures. Although artificial wood structures can be used to improve fish habitat in various aquatic ecosystems, they should be considered to be a complementary or interim habitat enhancement technique. The recovery of natural dynamic processes at the watershed scale is the ultimate target of restoration programs.     

河流生境的评估方法及应用的研究进展

河流生境是水生生物赖以生存的物理、化学和生物环境的综合体, 是河流生态系统的重要组成部分。河流生境评价有助于掌握河流的生态健康状况, 识别河流退化的原因, 为河流的生态修复提供依据。文章梳理总结了20世纪80年代至2018年文献中报道的全球范围内河流生境评估的方法, 然后根据每种方法的侧重点和目标, 将它们分为预测模型法和多指标综合评估法两种类型, 并比较了它们各自的优势和不足。预测模型法适于长期的生境动态监测, 但该方法需要以自然无干扰的河流为参照, 并且需要大量历史数据, 统一评估不易实现; 多指标综合评估法评估相对快速方便, 但评估过程复杂, 且评价标准不一, 结果有一定的局限性。这些方法的适用范围从中小型的可涉水河流到较大的不可涉水河流, 但适用于大型不可涉水河流的生境评估方法和案例非常有限。通过分类整理, 发现我国河流生境评估方法多是参考国外几种常用的河流评估方法, 种类单一, 而且多是针对个别河流, 并且未对这些河流所在的流域的生境状况进行深入研究, 广适性较差。因此, 文章从以下几个方面对我国河流生境评估体系的发展提出几点建议: (1)确定科学和标准化的评分指标, 因地制宜, 以满足不同河流特征; (2)扩大评估范围, 从流域和景观尺度开展生境监测, 关注全流域的健康状况; (3)扩大时间尺度, 建立模型, 进行长期的动态评估; (4)鼓励政府宏观规划, 促进不同管理部门间的合作, 整合不同地区的河流生境数据并建立国家尺度的河流生境大数据库, 以实现我国河流生态健康的维护和流域的可持续发展。     

丹顶鹤多尺度生境选择机制——以黄河三角洲自然保护区为例

生境在鸟类生活史中发挥着重要的作用,关系到鸟类的生存和繁衍。由于鸟类对环境变化的响应发生在等级序列空间尺度上,基于多尺度的研究更能深入刻画鸟类-环境之间关系。以丹顶鹤(Grus japonensis)为研究对象,以其迁徙和越冬的重要地区-黄河三角洲自然保护区为研究区域,应用等级方差分解法和等级划分法,分析丹顶鹤与微生境、斑块、景观尺度因子之间的关系,探求丹顶鹤生境选择的主要影响因素和尺度。等级方差分解结果表明,在第1等级水平,景观尺度因子与微生境、斑块尺度因子之间的联合效应大于独立效应,景观尺度因子的独立效应大于微生境和斑块尺度因子;在第2等级水平,景观尺度上的景观组成因子重要性大于景观结构因子,微生境尺度上的植被和水分因子为重要影响因素。等级划分结果表明,景观尺度上,翅碱蓬滩涂、水体面积大小是主要影响因素;微生境尺度上,植被盖度和水深为主要限制因子;在斑块尺度上,斑块类型对丹顶鹤生境选择最为重要。研究认为,在黄河三角洲自然保护区,景观尺度是影响丹顶鹤生境选择的主要尺度,景观尺度因子通过与微生境和斑块尺度因子的独立和联合作用制约着丹顶鹤在保护区的生境选择和空间分布格局。建议加强对翅碱蓬滩涂、芦苇沼泽、水体等湿地生境的保护和管理,规范和控制保护区内人类活动强度。     

基于河流生境调查的东河河流生境评价

河流生境是河流生态系统的重要组成部分,是河流生物赖以生存的基础。以位于三峡库区腹心区域的典型山区河流东河为研究对象,采用河流生境调查(RHS)方法调查河流生境,选择河流生境质量评价指数(HQA)、河流生境退化指数(HMS)评估河流生境现状,分析生境质量和人为干扰的空间分布规律。结果表明,51个河段的HQA值介于24—66之间。29.4%河段的HQA为优,29.4%为良,23.5%为中,9.8%为较差,7.8%为差。从HMS看,7.8%的河段保持较自然状态,19.6%受到轻微的破坏,41.2%退化明显,27.5%退化严重,3.9%受到剧烈破坏。HQA与HMS存在显著的负相关关系。东河上、中、下游河段的HQA无明显差异,但HMS差异显著。从干扰来源看,东河上游和中游河流生境主要受引水式小水电、沿河公路、河道采砂影响。东河下游河流生境受高强度的土地开发(农业用地、建设用地),河道采砂,河堤、排污管、桥梁等水工构筑物的修建和三峡水库水位的波动影响。RHS评价结果能较直观地反映河流生境状况,以及导致河流生境质量衰退的原因。     

Microhabitat use by brown trout, Salmo trutta L. and Atlantic salmon, S. salar L., in a stream: a comparative study of underwater and river bank observations

Two methods, visual observation from the river bank and visual observation underwater by diving, were compared for microhabitat studies in young brown trout and Atlantic salmon in a stream. A wide range of habitat conditions were surveyed. Each method yielded different results with respect to microhabitat use. River bank observations missed small fish under surface turbulence and in deeper waters. Underwater observations missed small fish in shallow areas.     

Fish community changes after minimum flow increase: testing quantitative predictions in the Rhône River at Pierre-Bénite, France

1. Many aspects of the flow regime influence the structure of stream communities, among which the minimum discharge left in rivers has received particular attention. However, instream habitat models predicting the ecological impacts of discharge management often lack biological validation and spatial generality, particularly for large rivers with many fish species. 2. The minimum flow at Pierre‐Bénite, a reach of the Rhône river bypassed by artificial channels, was increased from 10 to 100 m³ s^?1 in August 2000 (natural mean discharge 1030 m³ s^?1), resulting in a fivefold increase in average velocity at minimum flow. Fish were electrofished in several habitat units on 12 surveys between 1995 and 2004. 3. Principal components analysis revealed a significant change in the relative abundance of fish species. The relative abundance of species preferring fast‐flowing and/or deep microhabitats increased from two‐ to fourfold after minimum flow increase. A change in community structure confirmed independent quantitative predictions of an instream habitat model. This change was significantly linked to minimum flow increase, but not to any other environmental variables describing high flows or temperature at key periods of fish life cycle. The rapidity of the fish response compared with the lifespan of individual species can be explained by a differential response of specific size classes. 4. The fish community at Pierre‐Bénite is in a transitional stage and only continued monitoring will indicate if the observed shift in community structure is perennial. We expect that our case study will be compared with other predictive tests of the impacts of flow restoration in large rivers, in the Rhône catchment and elsewhere.     

Simple predictions of instream habitat model outputs for fish habitat guilds in large streams

1. In the context of a generalised modification of hydraulic conditions in medium to large streams, modelling the impacts of stream regulation on fish communities in multiple streams is an important challenge for basic and applied freshwater ecology. Conventional instream habitat models such as PHABSIM link a hydraulic model with preference curves for various species to estimate habitat value changes with discharge in stream reaches. Despite world‐wide applications, they have been scarcely used in multiple sites with multiple species. 2. We assigned 21 size classes of European fish species to four habitat guilds (cluster analysis grouping size classes with comparable microhabitat preference curves). Then, we ran a conventional instream habitat model on 28 French stream reaches belonging to the `barbel zone', to estimate habitat values versus discharge curves for the 21 size classes. We summarised the outputs as mean habitat values for guilds, and tested if they were predictable from average characteristics of reaches (discharge, depth, width, particle size). 3. As was obtained elsewhere for populations, habitat values for guilds were strongly related to average, dimensionless characteristics of reaches. The Reynolds number of reaches, equivalent to a discharge per width unit, reflected most of the discharge‐dependent changes in habitat values (within reaches). In particular, habitat values of species preferring bank (respectively midstream) microhabitats decreased (respectively increased) with increasing Reynolds number. The Froude number at median discharge was the major predictor of reach‐dependent but discharge‐independent variations in habitat values. Habitat values of species preferring riffle versus pool or bank microhabitats were higher in reaches with high Froude numbers. These relationships were consistent with existing knowledge on the different species. 4. Such results suggest that the input variables required to estimate habitat values for fish communities can be greatly simplified, as illustrated by a general estimation of the sensitivity of species preferring midstream habitats to discharge changes in any reach. Cost‐efficient alternatives to conventional instream habitat models should facilitate their validation in multiple sites, a point that remains critical in instream habitat modelling of fish communities.     

An index to track the ecological effects of drought development and recovery on riverine invertebrate communities

In rivers, the ecological effects of drought typically result in gradual adjustments of invertebrate community structure and functioning, punctuated by sudden changes as key habitats, such as wetted channel margins, become dewatered and dry. This paper outlines the development and application of a new index (Drought Effect of Habitat Loss on Invertebrates – DEHLI) to quantify the effects of drought on instream macroinvertebrate communities by assigning weights to taxa on the basis of their likely association with key stages of channel drying. Two case studies are presented, in which the DEHLI index illustrates the ecological development of drought conditions and subsequent recovery. These examples demonstrate persistent drought effects months or several years after river flows recovered. Results derived using DEHLI are compared with an established macroinvertebrate flow velocity-reactive index (Lotic-invertebrate Index for Flow Evaluation – LIFE score) and demonstrates its greater sensitivity to drought conditions. Data from a number of rivers in south east England were used to calibrate a statistical model, which was then used to examine the response of DEHLI and LIFE to a hypothetical multi-year drought. This demonstrated a difference in response between sampling seasons, with the spring model indicating a lagged response due to delayed recolonisation and the autumn model differentiating habitat loss and flow velocity-driven responses. The application of DEHLI and the principles which underlie it allow the effects of drought on instream habitats and invertebrates associated with short or long term weather patterns to be monitored, whilst also allowing the identification of specific locations where intervention via river restoration, or revision of existing abstraction licensing, may be required to increase resilience to the effect of anthropogenic activities exacerbated by climate change.     

Characterization of hydraulic habitat and retention across different channel types; introducing a new field-based technique

Understanding the interactions between physical habitat and aquatic biodiversity has become a key research objective in river management. River research and management practitioners are increasingly seeking new methodologies and techniques for characterizing physical habitat heterogeneity. The physical biotope has been widely employed as the standard mesoscale unit in river surveys. However, few surveys have quantified the combined physical heterogeneity at the meso- and microscale scale via a single technique. This paper describes a new field methodology for assessing variations in hydraulic habitat and retention across different channel types (e.g. step-pool, bedrock, plane-bed and pool-riffle). Hydraulic habitat and retention was measured by timing 100 flow tracers across a 100-m stream length, and recording the types of trapping structures. The pattern of flow tracers and retention varied significantly between channel types and structures. Rocks (boulders and cobbles) were more important retentive structures than eddies and snags (woody material and vegetation). The results indicate the importance of a diverse hydraulic environment, woody material and channel substrate character in increasing physical heterogeneity within a stream reach. The findings suggest that the field methodology may be an effective tool to assess differences in physical heterogeneity pre and post river restoration activities.