Large-scale assessments of river health using an Index of Biotic Integrity with low-diversity fish communities

1. Effective tools are needed to measure the ‘health’ of rivers at scales large enough to be useful for management. Indicators for assessing the complex of variables that constitutes river health need to be ecologically based, efficient, rapid and consistently applicable in different ecological regions. 2. A large-scale survey of rivers in New South Wales, Australia provided data to test the Index of Biotic Integrity (IBI). The IBI employs the fish-community attributes, identified using regional and river-size data, expected for a river reach of excellent environmental quality. It uses metrics based on species richness, abundance, community structure and the health of individual fish. IBI metrics were established to suit a relatively low-diversity and unspecialized freshwater fish fauna in south-eastern Australia, totalling 55 species. 3. The IBI was able to discriminate between relative levels of environmental quality within a diverse set of stream systems and four presumptive ecological regions. The index was validated by testing the repeatability of scores, and by comparison of IBI scores at eighty sites with an independent measure of potential catchment condition, the River Disturbance Index. 4. Assessments of metric performance showed that eleven of the twelve metrics contributed satisfactorily. One metric based on trophic guild performed poorly and should be deleted from the index. Six other recommendations are made to enhance the performance of the IBI. 5. Results show that, while all large rivers have been disturbed, rivers in the Murray region and those in many coastal montane areas are particularly degraded. 6. The IBI results presented here demonstrate a validated method for large-scale monitoring of river health based on a fish fauna of limited diversity, in the absence of suitable reference sites.     

THE LIMNOLOGY OF SOME SOUTH AFRICAN IMPOUNDMENTS I. THE PHYSICO-CHEMICAL LIMNOLOGY OF HARTBEESPOORT DAM

SUMMARY

Hartbeespoort Dam is a eutrophic, warm monomictic lake with overturn occurring in April. The lake is stratified for about six months of the year and in late summer the stratification appears stable. Light penetration in the dam depends both on the inflow of turbid water as well as on the magnitude of the algal population. In summer the surface waters are often super-saturated with oxygen, whilst the hype limnion is anaerobic. The concentrations of nitrogen compounds, phosphate, Na, K, Ca, CI and SO₄ are higher in waters entering the dam via the Crocodile River. Nitrogen compounds arc the primary growth-limiting nutrients for algal growth and phosphate is the secondary growth-limiting nutrient. Phosphate concentrations in the water have increased approximately a hundredfold since 1928 and NO₃ ?N concentrations about threefold. The pH as well as the mineral content of the dam have also increased over the last 50 years.     

Relations quantitatives entre les populations de bryophytes aquatiques et la pollution des eaux courantes. Définition d'un indice de qualité des eaux

Résumé L'étude physico-chimique des eaux, couplée à celle de la répartition quantitative des espèces bryophytiques aquatiques et subaquatiques de la Sambre, de la Somme et de la Meuse (Belgique et Nord de la France), permet de tirer quelques conclusions quant à la résistance de ces espèces aux différents types de pollutions.La synthèse multivariable des résultats aboutit à l'élaboration d'un indice de qualité des eaux, qui est comparé avec l'indice similaire de Descy, relatif aux diatomées benthiques.

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The physico-chemical analysis of the waters, in conjunction with the quantitative distribution of the aquatic and subaquatic bryophytes in the rivers Sambre, Somme and Meuse (Belgium and North France), has led to conclusions about species resistance to different kinds of pollution.The data's multivariable synthesis gives a quality index of water and permits comparison with Descy's index for benthic diatoms.

Recherches bénéficiant de l'appui du Fonds de la Recherche Fondamentale Collective: programme du Centre de recherches fondamentales sur les bioindicateurs de la pollution des milieux continentaux.     

Developing a wetland IBI with statewide application after multiple testing iterations

An index of biotic integrity (IBI) is a frequently used approach for assessing the ecological integrity of streams with fish and macroinvertebrates the faunal assemblages most commonly used as indicator taxa. The IBI approach has been much less commonly applied to wetlands, despite the legal, policy and scientific need to assess wetland condition and develop ecological performance goals for wetland creation, restoration and enhancement. While some IBIs are sophisticated systems with statewide application that have undergone one or more testing iterations, many published IBIs are derived from single data sets of a single class of aquatic resource with limited geographic application. The State of Ohio initiated development of a wetland IBI using vascular plants in 1996. Sampling methods were investigated and ultimately a plot-based method was adopted. Potential attributes and different human disturbance gradients were evaluated in several studies. Ultimately, IBIs for emergent, forest and shrub dominated wetlands were developed. Data from the Vegetation IBI-emergent (VIBI-E) is presented to illustrate this process. Subsequent testing and refinement is a critical step in the development of a robust IBI with more than local application. Throughout its initial development (R² = 0.863, p < 0.001), first major testing iteration (R² = 82.2%, p < 0.001), second test iteration (R² = 75.0%, p < 0.001) and third test iteration (R² = 82.1%, p < 0.001), the VIBI-E has remained significantly correlated with the disturbance gradient. Eight of the original 10 metrics proposed continued to have significant and interpretable relationships with the disturbance gradient, with 4 metrics remaining completely unchanged, and 4 undergoing relatively minor modifications, and 2 being replaced. The VIBI-E and its component metrics were also evaluated against a new disturbance gradient (Landscape Development Index or LDI), derived from land use percentages within a 1 km radius of the wetlands, that was not used during VIBI-E development. The VIBI-E score and 9 of 10 metrics were significantly correlated with the LDI disturbance gradient providing separate confirmation of the VIBI. The Vegetation IBI-E consistently and reliably assessed wetland condition across the whole range of wetland types throughout Ohio's ecological regions.     

Relationships between mesohabitats, ichthyological communities and IBI metrics adapted to a European river basin (The Meuse, Belgium)

We investigated the influence of mesohabitats on fish communities and on attributes of a multimetric index of fish integrity in the River Meuse basin. Three consecutive 150 m sectors in a Meuse tributary (Ourthe, Belgium), each divided in two or three sub-sections presenting various percentages of mesohabitats (riffles, runs and pools), were sampled by electrofishing. In each sub-section, relative and absolute biomasses of each fish species were estimated. The presence of limnophilic cyprinids was inversely correlated (r ² = 0.70 and 0.56 for absolute and relative biomass, respectively) with the percentage of riffles. Salmonids preferred runs and their absolute biomass was highly dependent (r ² = 0.71) on the proportion of this mesohabitat, whereas biomass of limnophilic cyprinids was highly correlated (r ² = 0.75 and r ² = 0.82 for absolute and relative biomass, respectively) with pools. A positive correlation (r ² = 0.58) was established between relative biomass of predators and the percentage of this mesohabitat. An IBI was calculated for the three sectors on the basis of results from the entire Meuse catchment. Scores of most metrics showed low variation among sectors but values of two metrics (% of individuals as tolerant, % of individuals as ubiquitous spawners) were greatest in sector 2, where pools predominated. Further, the lowest IBI score (51/65, integrity class: fair to good) was recorded in sector 2 where pools dominated, while sector 1 (where runs dominated) obtained the highest score (63/65, integrity class: excellent). Sector 3 which has a balanced proportion of riffles and runs obtained an intermediate score (57/65). Considering the response of IBI to the natural variation of mesohabitat proportions, it appears that an accurate sampling requires the prospection of a variety of mesohabitats (with a majority of runs) for the evaluation of river quality.     

广西河池地区河流基于鱼类的生物完整性指数筛选及其环境质量评估

为促进生物完整性评价法在中国的应用,加强珠江上游广西河池地区河流环境质量监测,该研究以鱼类为研究对象,初步构建了包含21个指标在内的广西河池地区河流基于鱼类的生物完整性评价的指标体系。根据鱼类调查所收集数据,结合历史资料的记录,对这些指标进行筛选和赋值,最终确立了6个指标,用于建立适合广西河池地区河流的基于鱼类的生物完整性指标体系;应用此指标体系对该地区部分河流(河段)进行了评价。评价的结果表明,小环江鱼类完整性为好;红水河、龙江和大环江为一般;刁江为极差。评价的结果与河流受人为干扰的实际情况相吻合,研究构建的评价体系可供河池周边地区使用和借鉴。生物完整性评价是水域环境质量监测的重要手段,为使生物完整性评价更加科学和客观,应加强生物完整性与环境因子之间关系的研究。     

Developing biological indicators from diverse data: The Potomac Basin-wide Index of Benthic Integrity (B-IBI)

A Basin-wide Index of Benthic Integrity (B-IBI) was developed to uniformly assess aquatic ecosystem health of non-tidal, wadeable streams in the multi-jurisdictional Potomac River basin (US). Multiple datasets were merged and used to identify stream classes and discriminating biological metrics. The index (aggregated metric scores) accurately identified 95% of impaired sites. A jackknife cross-validation procedure confirmed the accuracy of the B-IBI. B-IBI assessments generally compare favorably to basin states’ assessments derived from the same data. A habitat quality matrix which includes an indicator of anthropogenic alterations and disturbances is recommended. The Potomac B-IBI is more useful than existing state-specific indexes for stream health comparisons across jurisdictional boundaries and basin-wide. The Potomac B-IBI can improve understanding of water quality issues in the basin and enhance the abilities of water quality managers to make well-informed decisions concerning the basin's non-tidal waters.     

Status assessment in acid-sensitive and non-acid-sensitive Maryland coastal planin streams using an integrated biological,chemical, physical,and land-use approach

This study was designed to: (1) evaluate the ecological status of acid-sensitive and non acid-sensitive Maryland coastal plain streams using biological (Index of biotic Integrity [IBI] for fish), chemical and physical habitat conditions; (2) determine if a low IBI for coastal plain stream fish can be related to stream sensitivity from acidic inputs and (3) correlate land use activities and watershed size in the coastal plain streams with biological, chemical and physical conditions. IBI values obtained using 12 community metrics for Maryland coastal plain stream fish demonstrated that there were no significant differences in these values when acid-sensitive and non-acid-sensitive streams were compared. However, other complementary data in acid-sensitive streams such as absence of the acid-sensitive species, blacknose dace and higher numbers and biomass of tolerant species suggested that these streams may be impacted. IBI values were also found to be negatively correlated with various trace metals in acid-sensitive streams but not in non-acid-sensitive areas. Chemical conditions such as trace metals and nutrients were associated with land use activities. Highest concentrations of trace metals (chromium, nickel, and cadmium) were found in streams with the highest percentage of low residential housing. Nitrate concentrations were significantly higher in streams found in agricultural areas than in forested areas. Agriculturally dominated streams with highest nitrate concentrations (> 10 mg l^-1) also contained the highest percentage of livestock feeding operations. The mean IBI score for streams draining agricultural land was higher than the mean value for forested streams when all streams were compared. However, when several streams that were only marginally forested (< 50%) were removed from the analysis, the IBI scores did not differ significantly by land use. Two physical habitat indices exhibited a strong associated with each other. Each habitat index also correlated with IBI values.     

Measuring the responses of macroinvertebrate communities to water pollution: a comparison of multivariate approaches, biotic and diversity indices

The responses of macroinvertebrate communities to pollution by sewage effluent in the River Trent system (UK) were investigated using a variety of multivariate approaches, biotic indices and diversity indices. It was found that multivariate analyses clearly illuminated the change of community structure along the pollution gradient. CY Dissimilarity Measure (CYD)-based Non-Metric Multidimensional Scaling (NMDS) appeared to perform better than DCA and clustering. Species richness, the BMWP, BMWP-ASPT, the Chandler Score, Chandler-ASPT could detect the effects of major pollution. However, these indices showed varying sensitivity to different ranges of pollution, for example, Chandler-ASPT and BMWP-ASPT are more sensitive to the change in clean/slightly polluted range than in the moderate/very polluted range. The diversity indices were the least informative. The advantages and disadvantages of the various approaches were discussed.     

An advanced Index of Biotic Integrity for use in tropical shallow lowland streams in Costa Rica: Fish assemblages as indicators of stream ecosystem health

This paper presents an advanced version of the Index of Biotic Integrity (IBI), a multimetric index to indicate ecosystem health. The multimetric index has been adapted in such a way that it not only indicates overall condition but also specific causes of environmental disturbance. The newly developed index (a) uses data of tolerant as well as intolerant species in a single metric to indicate environmental disturbance, (b) does not require knowledge about species from the literature, and (c) can be applied to artificial landscapes.The metrics proposed here consist of indicator species assemblages that are selected directly for their relationship with an environmental component or specific type of environmental degradation. Thus, each metric indicates a type of environmental concern, which enables conservation practices to be targeted more effectively. Species assemblages for each single metric consist of a combination of species that can be negatively and positively related to environmental disturbances, providing a better indication of stream ecosystem health.The area studied was assumed to be too diverse for one single index. Canonical Indirect-Gradient Principal Component Analysis indicated that the optimal division of subindices based on stream typology was for streams with drainage basin sizes <10 km² and >10 km². Pearson Product-Moment Correlations were used to identify relationships between anthropogenic disturbances and the composition and abundance of fish species at impacted as well as undisturbed sites. This index proved to be useful for indicating overall stream ecosystem health as well as local onsite environmental disturbances or the environmental components of greatest concern. This index does require extensive information about measured levels of anthropogenic disturbances with the accompanying composition and abundance of fish species.     

The development of a Biotic Pollution Index for the River Nile in Egypt

This article describes the development of a Nile Biotic Pollution Index (NBPI) for the River Nile in Egypt. Chemical data were collected from 30 locations along the Nile from Aswan to Cairo and 21 sites within the river delta, incorporating a range of conditions from unpolluted to grossly polluted. Seven chemical variables were used to calculate a Nile Chemical Pollution Index (NCPI) for each site. Biological data were collected primarily using Artificial Substrate Samplers (ASS). The UK developed, Biological Monitoring Working Party (BMWP) biotic index and the BMWP-ASPT were applied to the data. A Nile Biotic Pollution Index (NBPI) and the NBPI-ASPT were obtained by incorporating more of the Nile taxa. There were highly significant regressions (P < 0.001) for both the UK and the Nile Pollution Index scores with the NCPI for the whole river. The modification of the UK indices improved the Nile Indices increasing the number of taxa recorded from 29 to 43 and the total number of recorded taxon occurrences from 377 to 490. The Nile Indices provided better discrimination at both ends of the pollution spectrum. The NBPI-ASPT was best for the river as a whole, and particularly for the river from Aswan to Cairo. The NBPI was much better in the delta than from Aswan to Cairo. These differences in performance were attributed to the fact that the NBPI-ASPT excludes information on taxon diversity. In clean waters there was a wide range of NBPI score suggesting that the biodiversity of taxa is dependent on other aspects of habitat quality. Conversely in the polluted delta the high score of an individual taxon is critical for the NBPI-ASPT as it may have a distorting effect. As the NBPI-ASPT was the most consistent biotic index it is recommended as the regular biological assessment and regulatory tool for Egypt to meet the requirements of the Convention for Biodiversity. Handling editor: R. Norris     

Food web structure provides biotic resistance against plankton invasion attempts

It is generally accepted that native communities provide resistance against invaders through biotic interactions. However, much remains uncertain about the types of ecological processes and community attributes that contribute to biotic resistance. We used experimental mesocosms to examine how zooplankton community structure, invertebrate predation, and nutrient supply jointly affected the establishment of the exotic Daphnia lumholtzi. We predicted that establishment would increase with declining biomass and diversity of native zooplankton communities and that an invertebrate predator (IP) would indirectly facilitate the establishment of D. lumholtzi due to its relatively long predator-deterring spines. Furthermore, we hypothesized that elevated nutrient supply would increase algal food availability and facilitate establishment. Only when the biomass and diversity of native zooplankton were significantly reduced, was D.␣lumholtzi able to successfully invade mesocosms. Although invertebrate predation and resource supply modified attributes of native zooplankton communities, they did not influence the establishment of D. lumholtzi. Overall, our␣results are consistent with observed population dynamics in invaded reservoirs where D.␣lumholtzi tends to be present only during the late summer, coinciding with historic mid-summer declines in native zooplankton populations. Lakes and reservoirs may be more susceptible to invasion not only by D. lumholtzi, but also by other planktonic species, in the late summer when native communities exhibit characteristics associated with lower levels of biotic resistance.     

Analysis of macrobenthic communities in Flanders,Belgium, using a stepwise input variable selection procedure with artificial neural networks

The effect of environmental conditions on river macrobenthic communities was studied using a dataset consisting of 343 sediment samples from unnavigable watercourses in Flanders, Belgium. Artificial neural network models were used to analyse the relation among river characteristics and macrobenthic communities. The dataset included presence or absence of macroinvertebrate taxa and 12 physicochemical and hydromorphological variables for each sampling site. The abiotic variables served as input for the artificial neural networks to predict the macrobenthic community. The effects of the input variables on model performance were assessed in order to identify the most diagnostic river characteristics for macrobenthic community composition. This was done by consecutively eliminating the least important variables and, when beneficial for model performance, adding previously removed ones again. This stepwise input variable selection procedure was tested not only on a model predicting the entire macrobenthic community, but also on three models, each predicting an individual taxon. Additionally, during each step of the stepwise leave-one-out procedure, a sensitivity analysis was performed to determine the response of the predicted macroinvertebrate taxa to the input variables applied. This research illustrated that a combination of input variable selection with sensitivity analyses can contribute to the development of reliable and ecologically relevant ANN models. The river characteristics predicting presence or absence of the benthic macroinvertebrates best were the Julian day, conductivity, and dissolved oxygen content. These conditions reflect the importance of discharges of untreated wastewater that occurred during the period of investigation in nearly all Flemish rivers.     

四川壤塘县绰斯甲河段鸟类资源初步调查及区系分析

四川壤塘县处于中国古北界与东洋界的过渡地带,因此研究其鸟类区系具有一定意义。2010年8月和12月对壤塘县绰斯甲河段鸟类资源及区系进行了初步调查。结果表明,该区共有鸟类152种,包括留鸟102种,夏候鸟38种,冬候鸟5种,旅鸟7种。其中,中国特有鸟类12种,国家Ⅰ、Ⅱ级重点保护鸟类和省级重点保护鸟类20种。     

Benthic, Drifting and Marginal Macroinvertebrate Assemblages in a Lowland River: Temporal and Spatial Variations and Size Structure

Aquatic macroinvertebrates living in anastomosing lowland rivers use different habitats and respond differently to the hydrological regime. In this paper, the structure and composition of benthic, drifting and marginal macroinvertebrate assemblages are analyzed in the lowland river Ctalamochita (Córdoba, Argentina). The assemblages were studied in an annual cycle; a comparison among the composition of benthos, drift and marginal fauna was carried out; and size structure of the assemblages was characterized. Samples were obtained from two sites: a rural and an urban site. In total 73 taxa of aquatic macroinvertebrates were collected. Benthos was characterized by Chironomidae and Oligochaeta; marginal fauna was mainly constituted by Coleoptera, Heteroptera, Decapoda, the Trichoptera Nectopsyche sp., Ephemeroptera and Odonata. Drifting assemblage was composed by macroinvertebrates from local and remote upstream benthos, and from the marginal zone. Marginal fauna diversity was higher than benthos and drift. Total biomass of the assemblages pooled together was relatively equitably among size classes. Larger size classes consisted of organisms from the marginal zone whereas the smallest ones were composed by benthic and drifting organisms. In the study area there is habitat partitioning in the lateral dimension of the river. Marginal fauna was more diverse due to the asymmetry of transport and deposit processes, which generate a heterogeneous habitat in the bankside. The relation between fine substrate and high current velocity determines an unstable habitat in the central channel, which makes colonization by benthic macroinvertebrates difficult.