Fish assemblages in European Western Highlands and Western Plains: a type-specific approach to assess ecological quality of running waters

Abstract  After typological pre-classification of 398 calibration sites, fish-based metric models were used to predict the impact of human activities on river quality in European Western Highlands and Western Plains ecoregions. Calibration sites were grouped into six assemblage types and according to their geomorphology; test sites were assigned to their corresponding assemblage type. Five anthropogenic variables were used to describe the impact level of each site and stepwise discriminant analysis was performed to: (i) avoid redundancy between metrics; (ii) examine how selected metrics discriminated impact classes and (iii) predict ecological status for each site of the given fish type. Globally, this approach predicted the impact class correctly for 64% of sites. The difference between observed and predicted impact was more than one class for only 2.5% of the sites. When validating this approach with an independent data set, differences between observed and predicted impact values never exceeded 2 impact classes, but these differences varied in size among countries.     

Environmental assessment of boreal rivers using fish data – a contribution to the Water Framework Directive

Abstract A fish‐based assessment method was developed to estimate the ecological status of boreal rivers. Electric fishing data were collected from 902 rapids, together with information on the land use, channel modification and water chemistry. Discriminant function analysis was used to select fish variables that most correctly classified the undisturbed reference sites and human impacted sites into exact classes. The relationship between the level of human alteration and fish metrics was examined. Five metrics were selected for the index: the number of fish species, proportion of sensitive species, proportion of tolerant species, density of cyprinid individuals and the density of age‐0+ salmonids. The value for each metric (between 0 and 1) was calculated according to a point estimate for classical probability. The index is used to estimate the ecological classification of rivers according to the EU Water Framework Directive.     

Ecological traits of fish assemblages from Mediterranean Europe and their responses to human disturbance

Abstract  Mediterranean river systems are characterised by more diverse fish assemblages and regional ecological processes compared with the rest of Europe. A data set from Mediterranean France, Iberia and Greece (∼2000 sites) was used to describe the characteristics of fish assemblages, explore their responses to anthropogenic disturbance and analyse the implications for river quality assessment. There was a southwards decline in species richness per site, but endemicity and proportion of alien species increased. Sites in the eastern Mediterranean had higher endemicity, lower site richness and lower number of alien species than sites in western Mediterranean Europe. Assemblage composition differed between Mediterranean sub-regions, but was dominated by three major fish types: a salmonid fish type common throughout the study area and two cyprinid-dominated fish types (in some sub-regions, Salmo trutta L. is present but not numerically dominant), corresponding to a gradient in hydrological and temperature regimes. Metric responses to perturbation were compared with those found at the European (larger scale) and basin (smaller scale) levels. Overall metric response was weaker in this Mediterranean application. The best responses to human pressure were usually obtained with abundance-based metrics and included the contribution of naturalised alien species. Some widespread alien species contributed to the response to anthropogenic alteration (notably Cyprinus carpio L. and Lepomis gibbosus (L.)).     

Assessing the health of European rivers using functional ecological guilds of fish communities: standardising species classification and approaches to metric selection

Abstract  The functional ecological guild approach is the cornerstone for the development of Indices of Biotic Integrity and multi-metric indices to assess the ecological status of aquatic systems. These indices combine metrics (unit-specific measures of a functional component of the fish community known to respond to degradation) into a single measure of ecological assessment. The guild approach provides an operational unit linking individual species characteristics with the community as a whole. Species are grouped into guilds based on some degree of overlap in their ecological niches, regardless of taxonomic relationships. Despite European fish species having been classified into ecological guilds, classification has not been standardised Europe-wide or within the context of classifying species into guilds from which metrics can be developed for ecological assessment purposes. This paper examines the approach used by the EU project FAME to classify European fish species into consistent ecological guilds and to identify suitable metrics as basic tools for the development of a standardised ecological assessment method for European rivers to meet the requirements of the Water Framework Directive.     

Development of fish-based assessment method for the ecological status of rivers in the Baltic region

Abstract  A fish-based assessment method for determining the ecological status of rivers in the southern part of the Baltic region was developed, classifying fish assemblages of near natural sites, and testing the response of a wide range of fish metrics to human pressure. However, the potential for developing a statistically robust method was limited because of insufficient data and the impact of fishery exploitation. A combination of expert judgement, historical data and spatially based methods were needed to establish reference conditions and classification criteria for fish metrics. The final list of metrics (6–9 metrics per six different river types) comprises five ecological guilds (feeding, overall tolerance, habitat, migration and spawning strategy) and three sentinel (dominant) species ( Salmo trutta L., Cottus gobio L. and Alburnoides bipunctatus [Bloch]). The method tends to underscore the ecological status of specific river types because the selected metrics probably do not account for all possible variability in fish community response to degradation, as some community-specific characteristics were poorly or not represented. Exploitation pressure might have considerable effects on functionality of fish metrics. Results suggest that the method needs modification to account for these limitations.     

Processes of collating a European fisheries database to meet the objectives of the European Union Water Framework Directive

Abstract  FIsh Database of European Streams, a common database for the FAME project, was merged using existing data on electric fishing and environmental data. FIsh Database of European Stream is a relational database with eight tables. Metrics based on classification of fish species into guilds were calculated, and provided in separate tables. FIsh Database of European Stream contained information about 150 freshwater fish species, from 12 countries, 17 ecoregions, 40 main river regions, 2651 rivers and 8228 sites. Examples of data coverage and use are given. Relationships between environmental variables were illustrated using principal component analysis, which resulted in three environmental components – latitude, size and altitude. Environmental component scores were correlated with fish metrics used in the European Fish Index. Results exemplify how fish guilds reflect gradients in environmental variation. Benefits and problems concerning standardisation and data availability at the global level are discussed.     

Development and evaluation of a fish‐based index to assess biological integrity of Mediterranean streams

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Fish‐based assessment of ecological status of Finnish lakes loaded by diffuse nutrient pollution from agriculture

Abstract The European Union Water Framework Directive stipulates that pressures on surface waters due to diffuse loading of nutrients have to be taken into account in determination of their ecological status. A Finnish data set of fish communities in 178 lakes was used to assess the effects of agriculture‐induced nutrient loads on the ecological status of lakes. The lakes were divided to reference (n = 100) and impacted sites (n = 78) based on water quality, land use and nutrient load data. Fish sampling was conducted by standardised gill net test fishing. A fish‐based classification tool of the four parameters (EQR4) was applied to assess the ecological status of lakes. The parameters included were: mean total biomass of fish per gill net night, number of fish individuals per gill net night, biomass proportion of cyprinid fishes and the presence of indicator species. The analysis resulted in a median EQR4 value of 0.78 (good status) for reference lakes and 0.56 (moderate status) for affected lakes. Thus, the classification tool gave an acceptable output for different nutrient‐loaded lakes.     

Nested patterns of spatial diversity revealed for fish assemblages in a west European river

Abstract –  The longitudinal distribution of fish assemblages across a large west European river basin, the Garonne river (south-west France) were investigated using a self-organising map. This nonlinear statistical method was employed to classify sampling sites according to their species composition. We found three main nested patterns in an aggregated hierarchy: a replacement and succession of species along a gradient without defined boundaries, four main zones of fish assemblages and an upstream-downstream shift of fish communities. We suggest that fish assemblages are too complex to be identified with a single species as in the zonation model, and that the diversity patterns found might be part of the same ecological process influencing fish assemblages on different spatial scales. Thus, discrepancies in the analysis of longitudinal patterns of fish communities in streams may have been basically a matter of local conditions and of conceptual perception.     

Development of a fish-based index for the assessment of river health in Europe: the European Fish Index

Abstract  A fish-based index applicable at the pan-European scale should encompass the relative importance of regional and local factors influencing the distribution of riverine fish. An effective way of using information available from fish assemblages to establish such a multimetric index is through the use of the reference condition approach that involves testing a fish assemblage exposed to a potential stressor against a reference condition. In this study, a variety of metrics based on count and abundance data and reflecting different aspects of the fish assemblage structure and function were selected from the literature for their potential to indicate degradation. Logistic and multiple linear regression procedures were applied, using an initial data set of 1000 reference sites fairly evenly distributed across European rivers (11 countries) and defined by some easily measured regional and local characteristics, to elaborate the simplest possible response model that adequately explains the observed patterns of each metric for a given site. A final list of 10 metrics was retained and the European Fish Index was tested using new independent datasets. The advantage of the resulting index to serve as a practical technical reference for cost-effective biological assessments of lotic systems in Europe is related to its ability to encompass basins and river size, and its sensitivity to physical and chemical alteration of the river ecosystem.     

北盘江光照水电站建设前后鱼类资源变化

2009年9月和2010年5月,对北盘江光照水电站影响河段鱼类资源进行现场调查,采集鱼类45种,其中18种为新记录种,各河段鱼类组成特点与生态类型相符。结合相关文献资料,确定调查河段鱼类共71种,其中珍稀濒危鱼类4种,珠江水系特有鱼类3种。光照电站的建设对库区河段的鱼类资源影响显著,喜静缓流生境鱼类占76.5%,喜急流...     

Use of ecological niche modelling to predict distributions of freshwater fish species in Kansas

Abstract – An essential innovation in aquatic biodiversity research would be a robust approach to accurately predict species’ potential distributions. In this paper, I conduct an analysis to test the efficacy of ecological niche modelling for predicting fish species’ potential distributions using an artificial‐intelligence algorithm, the Genetic Algorithm for Rule‐Set Prediction (GARP). Models of species’ ecological niches are developed using GARP, and projected onto geography to predict species distributions. To test the validity of this approach, I used freshwater fish distribution data for twelve fish species occurring in Kansas. These taxa were chosen to represent phylogenetic, distribution, and habit diversity. I subset these data by omitting half of the counties from model building, and test models using the omitted counties. Models were tested using Receiver Operating Characteristic (ROC) analyses. Of the species tested, all were statistically significant with the models showing excellent predictive ability. Omission errors across taxa ranged from 0 to 17%. This inferential capacity opens doors to many synthetic analyses based on primary point‐occurrence data.     

应用鱼类生物完整性指数评价北运河河流健康

评估北运河水系生态状况，为判别北运河水系水生态恢复成效提供参考。2020 年5月、8月调查了北运河13个采样点的鱼类及生境状况，采集到鱼类20种，分属3目9科18属。采用F-IBI评价北运河健康状况。选择人类活动干扰较轻的点作为参照点，从物种种类组成与丰富度、营养结构、耐受性和敏感性、繁殖共位群以及鱼类数量等5个方面构建F-IBI候选指标体系，然后依据分布范围检验、敏感性分析和相关性检验，筛选出F-IBI 核心指标体系，包括鱼类物种数、Shannon-Wiener 多样性指数、鲤科物种数百分比、漂流性卵鱼类个体数百分比、沉性卵鱼类个体数百分比、黏性卵鱼类个体数百分比、外来物种数量所占比例。采用比值法计算各采样点F-IBI值，并将其划分为“优”“良”“中”“一般”和“差”5个健康评价等级，评价各采样点健康状况。评价结果表明：北运河健康状况整体为中等偏上，其中7.69%的采样点健康状况为“优”，23.08% 的采样点健康状况为“良”，53.85%的采样点健康状况为“中”，15.38%的采样点健康状况为“一般”。北运河水生态治理取得一定成效。     

筑坝河流鱼类生物完整性研究——以珠江流域红水河为例[收稿日期：2021-08-30

基于红水河流域开发特点和鱼类群聚组成特征，构建红水河鱼类生物完整性评价指标体系，评价梯级开发对红水河不同生境类型的鱼类生物完整性的影响。河流参照状态和基准值由1982—1994年鱼类历史监测数据分析得到；监测值是2013年调查的鱼类数据；现状值为2018年鱼类数据。针对红水河鱼类区系特点和高强度水电开发特征，选取总种类数占期望值比例、鲤科鱼类所占比例、鲿科鱼类所占比例、鲇科鱼类所占比例、耐受性鱼类个体所占比例、渔获物中出现的科数所占比例、杂食性鱼类个体所占比例、底栖动物食性鱼类个体所占比例、顶级肉食性鱼类所占比例和外来种个体所占比例等10个指标构建红水河IBI指标体系。结果表明：2013年25个采样江段的IBI值为38 ~ 80分，均值62分。其中，24%的江段生物完整性等级为“好”；32%的江段生物完整性等级为“一般”；44%的江段生物完整性等级为“差”。从生境类型来看，支流生物完整性明显优于水库、库尾回水区。此外，现状数据评价的结果为：2018年红水河IBI值为64分，高于2013年均值62分，生物完整性均处于“一般”等级。     

Salinity and geomorphology drive long‐term changes to local and regional fish assemblage attributes in the lower Pecos River,Texas

River systems throughout arid regions worldwide have been heavily impacted by human activities, resulting in long‐term ecological consequences. The lower Pecos River in the Trans‐Pecos region of Texas is no exception, having undergone anthropogenic changes that include decreased flow, elevated salinity, species loss and species invasion. We compared historical and contemporary fish assemblage attributes from the Pecos River at local (site‐specific) and regional (Trans‐Pecos region) scales across a 24‐year time period. Fish assemblage data were collected in October 1987 and 2011, by seining at 15 sites spanning 430 km of the river in Texas. Additionally, we examined contemporary environmental conditions to determine species–environment relationships. We found that fish assemblages were significantly different between time periods, likely due to increased salinisation in the upper half of the study region. Decreased species richness, species replacement and increases in euryhaline species were documented in the upstream sites. Freshwater springs lower the salinity and maintain flows in the downstream reach, allowing for maintenance of the native fish fauna. Careful management of regional aquifers, irrigation practices and petroleum waste water will be necessary for protecting biodiversity and environmental flows in the lower Pecos River.     

禁捕后长江鱼类资源监测的技术指标建议

为了确定监测时长、监测网具、站位布局对禁捕后长江鱼类资源监测评估的有效性,于2021年5—7月在长江中游10个站位开展了鱼类资源捕捞监测,每个站位连续监测15 d,从日捕获量、物种记录数、渔获物群落结构等3方面着手,对监测时长、监测网具、站位布局等的设置进行探讨。结果显示,连续11 d捕捞监测所得累计日均渔获量基本达到稳定,连续15 d捕捞监测可以记录到站位近70%的鱼类种类数,所得累计鱼类群落结构基本达到稳定。网具类型、规格的使用覆盖对监测结果中鱼类种类记录数、鱼类群落结构有明显影响,网具使用量对监测结果中日均渔获量有明显影响。10个监测站位间的鱼类群落结构具有明显差异,结合监测站位间的空间距离来看,鱼类群落结构具有较高的空间异质性。研究表明,为了保障评估结果的准确性,基于原始监测数据进行相关评估之前,有必要对监测数据的充分性、有效性进行检验,网具类型、规格和使用量对监测结果的影响应予以适当考虑,各具体江段的鱼类群落结构评估应由相应具体江段的监测结果来支撑。本研究将为长江流域重点水域全面禁捕后的水生生物资源监测评估提供科学支撑。     

Brook trout (Salvelinus fontinalis) movement and survival after removal of two dams on the West Branch of the Wolf River,Wisconsin

Dam removals allow fish to access habitats that may provide ecological benefits and risks, but the extent of fish movements through former dam sites has not been thoroughly evaluated for many species. We installed stationary PIT antennas in 2016 and 2017 to evaluate movements and survival of brook trout Salvelinus fontinalis in the West Branch of the Wolf River (WBWR) in central Wisconsin following removal of two dams and channel modifications designed to promote fish movement. These changes provided access to lacustrine habitats that might provide suitable winter habitat or act as ecological sinks. We used multistate models to estimate transition probabilities between river sections, to determine whether brook trout: (a) moved between multiple river sections and (b) entered lacustrine habitats as seasonal refuges, but eventually returned to lotic habitat. We also used a Cormack-Jolly-Seber model to evaluate whether apparent survival of brook trout in the WBWR was comparable to other populations. Few fish moved among river sections or used lacustrine habitat (<5% of tagged fish); most brook trout remained in sections where they were initially tagged, potentially due to quality habitat located throughout the river. Like other studies, brook trout in the WBWR appear to experience high mortality based on low number of detections, few physical recaptures and an estimated eight-month apparent survival rate of 0.27. In scenarios where fish can already access suitable habitat, removal of dams may not result in substantial increases in fish movement and colonisation of newly accessible habitat may not occur immediately.     

Assessing biotic integrity in a Mediterranean watershed: development and evaluation of a fish-based index

Abstract  Biological indicators for Mediterranean rivers are poorly developed. This study evaluates the effectiveness of the Index of Biotic Integrity approach (IBI) with fish assemblages in the Guadiana catchment, a typical Mediterranean watershed in Southern Portugal. Reference sites were selected from a set of 95 sites, using a multivariate approach. Fifty-five candidate metrics were screened for range, responsiveness, precision and redundancy. Final metrics included: proportion of native fish, number of intolerant and intermediate species, number of invertivore native fish, number of phyto-lithophilic and polyphilic species, and catches of exotics. The IBI scores correlated with composite gradients of human impact and differed significantly between reference and non-reference sites. Application of the IBI to an independent validation set with 123 sites produced results congruent with the development set and repeatable assessments at 22 sites showed concordance in IBI scoring. This application highlights the effectiveness of the IBI approach even with fish assemblages of limited diversity and ecological specialisation as in Mediterranean streams.