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.     

The ways in which fish use estuaries: a refinement and expansion of the guild approach

This study refines, clarifies and, where necessary, expands details of the guild approach developed by Elliott et al. (2007, Fish and Fisheries 8 : 241–268) for the ways in which fish use estuaries. The estuarine usage functional group is now considered to comprise four categories, that is, marine, estuarine, diadromous and freshwater, with each containing multiple guilds. Emphasis has been placed on ensuring that the terminology and definitions of the guilds follow a consistent pattern, on highlighting the characteristics that identify the different guilds belonging to the estuarine category and in clarifying issues related to amphidromy. As the widely employed term ‘estuarine dependent’ has frequently been imprecisely used, the proposal that the species found in estuaries can be regarded as either obligate or facultative users of these systems is supported and considered in the guild context. Thus, for example, species in the five guilds comprising the diadromous category and those in the guilds containing species or populations confined to estuaries are obligate users, whereas those in the marine and freshwater estuarine‐opportunistic guilds are facultative users.     

海州湾及邻近海域鱼类群落的营养功能群及其动态变化

根据2011年及2013―2016年春季和秋季在海州湾及邻近海域进行的渔业资源底拖网调查,对该海域鱼类群落营养功能群的组成及其季节和年间变化进行了研究。结果表明,海州湾及邻近海域鱼类群落可以划分为5个营养功能群,即虾食性、底栖动物食性、虾/鱼食性、浮游动物食性和鱼食性。整体来说,春季海州湾鱼类群落以底栖动物食性营养功能群为主,其中方氏云鳚(Enedriasfangi)在各年所占比例均较高;而秋季以虾食性营养功能群为主,小眼绿鳍鱼(Chelidonichthys kumu)为主要优势鱼种。从生物量组成角度分析,海州湾鱼类群落各营养功能群所占比例有明显差异,以虾食性和底栖动物食性的功能群为主,其次为虾/鱼食性,而浮游动物食性和鱼食性所占比例较小。方氏云鳚、小眼绿鳍鱼、长蛇鲻(Saurida elongata)、小黄鱼(Larimichthys polyactis)、狮子鱼(Liparis sp.)、玉筋鱼(Ammodytespersonatus)等6种鱼类为各营养功能群的主要优势种类。海州湾及邻近海域鱼类群落的营养功能群和优势种呈现出明显的季节和年间变化,海洋环境变化和鱼类的季节性洄游移动等是主要的影响因素。     

Isotopic trophic guild structure of a diverse subtropical South American fish community

Characterization of food web structure may provide key insights into ecological function, community or population dynamics and evolutionary forces in aquatic ecosystems. We measured stable isotope ratios of 23 fish species from the Rio Cuareim, a fifth‐order tributary of the Rio Uruguay basin, a major drainage of subtropical South America. Our goals were to (i) describe the food web structure, (ii) compare trophic segregation at trophic guild and taxonomic scales and (iii) estimate the relative importance of basal resources supporting fish biomass. Although community‐level isotopic overlap was high, trophic guilds and taxonomic groups can be clearly differentiated using stable isotope ratios. Omnivore and herbivore guilds display a broader δ¹³C range than insectivore or piscivore guilds. The food chain consists of approximately three trophic levels, and most fishes are supported by algal carbon. Understanding food web structure may be important for future conservation programs in subtropical river systems by identifying top predators, taxa that may occupy unique trophic roles and taxa that directly engage basal resources.     

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

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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.     

黄河口及其邻近水域鱼类生物完整性评价

根据2013—2014年在黄河口及其邻近海域进行的鱼类资源底拖网调查数据,并结合20世纪80年代和90年代的历史资料,依照黄河口水域鱼类区域组成特征,从鱼类种类组成、繁殖共位体、鱼类耐受性和营养结构等方面提出了12个评价指标,初步构建了黄河口水域鱼类生物完整性指数评价指标体系,并制定了评价标准,根据不同年代数据之间的差距分3个层次赋值打分,研究了黄河口水域鱼类生物完整性及其年代际变化。结果表明,20世纪80年代初期黄河口水域鱼类生物完整性表现为"极好"水平;90年代处于"差"水平;2013年处于"极差"的水平。与20世纪80年代初期相比,黄河口及其邻近水域的鱼类生物完整性呈下降趋势,人为因素对生态环境干扰较大,过度捕捞等造成黄河口水域鱼类种类减少甚至消失,黄河口水域生态健康状况下降。     

Fish and flows: Abiotic drivers influence the recruitment response of a freshwater fish community throughout a regulated lotic system of the Murray-Darling Basin,Australia

1. Fish assemblages in dryland rivers have life-history strategies that have evolved in response to environmental conditions and triggers, particularly water temperatures and flow regimes. The regulation of rivers through the construction of dams, weirs and other water diversion structures has altered natural flow regimes and the associated ecological processes of river systems worldwide.
2. Over a 3-year period, using standardized fish sampling and daily otolith ageing, the recruitment of eight freshwater fish species was monitored in response to various abiotic drivers, including hydrology and water temperatures, throughout the Macquarie River, a large regulated river system of the Australian Murray-Darling Basin.
3. A data-driven statistical classification system is provided that groups species into reproductive guilds, based on their recruitment response to hydrology and water temperature, specifically designed for use in environmental flow management.
4. The eight species were grouped into three distinct reproductive guilds that showed similar recruitment responses to the abiotic drivers. Murray-Darling rainbowfish, Murray cod, and eel-tailed catfish were considered as a single guild, characterized by seasonal recruitment during a relatively narrow thermal window under low to moderate stable discharges. The second group included common carp, bony herring, and golden perch, which recruited primarily in association with larger flow events. Un-specked hardyhead and Australian smelt formed a more differentiated guild, recruiting over a broad range of temperatures and discharges. Limitations associated with using a reproductive guild approach to simplify water management are discussed.
5. This study highlighted important relationships among hydrology, water temperatures, and successful recruitment that can, in turn, be used to inform development of adaptive flow management plans and effective use of environmental water for the conservation management of native fish communities. Important considerations in the design of studies that aim to examine relationships between recruitment and abiotic drivers are also discussed.

     

The guild approach to categorizing estuarine fish assemblages: a global review

Many studies have recently described and interpreted the community structure and function of fishes inhabiting estuaries and other transitional waters in terms of categories or guilds. The latter describe the main features of the fishes’ biology and the way in which they use an estuary. However, the approach has been developed by different workers in different geographical areas and with differing emphasis such that there is now a need to review the guilds proposed and used worldwide. The previous wide use of the guild approach has involved increasing overlap and/or confusion between different studies, which therefore increases the need for standardization while at the same time providing the opportunity to reconsider the types and their use worldwide. Against a conceptual model of the importance of the main features of fish use in estuaries and other transitional waters, this review further develops the guild approach to community classification of fish communities inhabiting those areas. The approach increases the understanding of the use of estuaries by fishes, their interactions and connectivity with adjacent areas (the open sea, coastal zone and freshwater catchments) and the estuarine resources required by fishes. This paper gives a global perspective on this categorization by presenting new or refined definitions for the categories, lists the synonyms from the literature and illustrates the concepts using examples from geographical areas covering north and central America, north and southern Europe, central and southern Africa, Australia and the Indo‐Pacific.     

Rhithronic and potamonic fishes coexist in wadeable streams under distinct metacommunity processes

Recent metacommunity ecology research has demonstrated that local communities can be divided into different guilds. We hypothesised that wadeable streams are occupied by fishes that follow distinct metacommunity processes. The mainstem is a river corridor for the potamonic fish guild (PFG) but represents a nonhabitat matrix for the rhithronic fish guild (RFG). Accordingly, the PFG should be filtered out from the headwaters by dispersal limitations or environmental filtering along the longitudinal gradient, and the guild should have a nested pattern of beta diversity. The RFG should be structured by the local species sorting, and the species turnover component should prevail. We sampled fishes in 42 streams distributed in four subbasins that were separated by at least one mainstem channel. We modelled the influences of spatial and environmental predictors using a partial redundancy analysis and variance partitioning and by quantifying the components of beta diversity that were associated with species turnover and nestedness. Both environment and space affected the structure of the RFG, owing to the influence of substrate type, riparian cover and presence of downstream barriers. The PFG was structured by only the influence of downstream barriers. Species turnover predominated within the RFG, and species nestedness dominated within the PFG. Our results support the hypothesis that potamonic and rhithronic guilds coexist in wadeable streams and follow distinct metacommunity assembly mechanisms. Potamonic guilds are structured by regional dispersal from the mainstem channels, whereas rhithronic guilds are sorted by local filtering along the longitudinal gradient in a spatially structured environment.     

钱塘江水系兰溪段鱼类资源现状

2016年3月—2017年11月,对钱塘江水系兰溪段的鱼类资源进行逐季度采样调查,对该水域鱼类种类组成、生态类型、优势种、多样性指数、群落结构、ABC曲线和捕获情况进行了分析。试验结果显示,共采集鱼类59种,隶属5目13科44属,其中,鲤科鱼类种类最多(67.8%);优势种为鲤鱼和似鳊;生态类型以中小型、杂食性、底层性鱼类为主;Margalef丰富度指数呈先增后减的趋势,2016年的Simpson多样性指数、Shannon-Wiener多样性指数和Pielou均匀度指数均呈逐渐减小的趋势,而2017年这3个指数除9月份最小外,其他月份变化差异不显著;鱼类群落结构季节变化差异显著,但处于稳定状态;鱼类资源严重小型化。     

A technical guide to develop a statistically valid fish-based index in compliance with the water framework directive: an evaluation for Turkish freshwaters

Fish are considered as reliable indicators of environmental quality and during the last decades several fish-based indices have been developed to assess the ecological status of water bodies in compliance with the water framework directive. The high number of fish species with a high degree of endemism, lack of knowledge on ecological requirements of certain fish species, absence of a complete dataset for reference conditions, and great variation among freshwater types complicate the development of fish-based indices for Turkish freshwaters. However, this is still possible using statistical approaches. This paper presents a practical guide which is mainly based on the recent approaches that have frequently been used in other countries worldwide. Data collection, metric selection and scoring, ecological quality ratio (EQR) calculation and validation steps are described and discussed with respect to the limitations and available data for Turkish freshwaters. The guide documented here, with minor adjustments, has a potential to be adopted as a fish-based assessment approach for the ecological status in freshwaters in Turkey and adjacent countries.

     

The utility of simple fish community metrics for evaluating the relative influence of fishing vs. other environmental drivers on Caribbean reef fish communities

Fish community metrics have been extensively investigated as indicators of fishing effects for ecosystem‐based fisheries management (EBFM) in temperate systems. Little similar work has been performed in the coral reefs of the Caribbean, where simple indicators are urgently needed. Here, we use 415 coral reef surveys throughout the Caribbean to assess the potential of four simple and intuitive fish community metrics, namely, fish biomass, fish density, average fish weight and species richness, to separate fishing effects from those of other environmental factors at both local (tens of kilometres) and broad (hundreds to thousands of kilometres) spatial scales. We found that these fish metrics differed considerably in environmental correlates and the spatial scales underlying fish metric–environment associations. Average fish weight and fish biomass were most sensitive to fishing indices at both spatial scales, although average fish weight responded more sensitively and specifically to fishing than fish biomass. Fish density and species richness were most sensitive to temperature over broad scales and to macroalgae and relief height over local ones. All fish metrics were negatively correlated with macroalgae over broad scales, supporting the utility of macroalgae to inform about the integrity of entire reef ecosystems. Most of the fish metric variance associated with fishing pressure operated over broad scales, highlighting the need for a Caribbean‐wide view of fish community status to establish local management objectives and avoid shifting baselines. Our study clarifies the utility of simple fish community metrics as indicators of fishing effects for EBFM in the Caribbean.     

Fish-based methods for assessing European running waters: a synthesis

Abstract  The European Union, Water Framework Directive (WFD) requires monitoring of riverine fish fauna. When the WFD came into force in 2000, most of the EU member states did not have fish-based assessment methods compliant to WFD requirements. Therefore, the objectives of FAME ( http://fame.boku.ac.at ), a project under the fifth R&D Framework Programme of the European Commission were to develop, evaluate and implement a standardised fish-based method for assessing the ecological status of European running waters. This paper synthesises the outputs of FAME and defines future research needs. Two different methodologies were used: the so-called spatially based modelling and the site-specific modelling, the latter leading to the European Fish Index (EFI). The advantage of the EFI is that, despite being a single index, it is applicable to a wide range of environmental conditions across Europe precluding the need for inter-calibration. The EFI will support the WFD towards harmonised/standardised assessment and management of running waters in Europe, thus enabling comparative analyses of the ecological status of running waters across Europe.     

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.     

同安湾浮游动物的基本特征及水质评价

本文根据1995年5月至1998年2月同安湾浮游动物的调查材料,阐明了同安湾浮游动物的种类组成、生物量、数量的平面分布、群落结构等基本特征,探讨了同安湾浮游动物与环境因子的关系。并用群落的多样性指数对同安湾的水质进行评价。结果表明浮游动物鉴定的种类有79种,分6个生态群落,其中低盐近岸生态群落是最主要的生态群落。1997年浮游动物种类数、生物量、群落的多样性、均匀度、丰度均比1995年高。从浮游动物多样性变化的结果分析:1995年该海域已受污染,1997年趋向好转。还分析了浮游动物与环境因子之间的关系,太平洋纺锤水蚤和盐度有密切相关,其一元线性回归方程为y=1016.91～32.23x。浮游动物的高生物量区形成幼鱼索饵场。