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A lectotype (male) and paralectotypes (male, female) of Pneumia vittata (Tonnoir, 1919) comb. nov. (= Pericoma crispi Freeman, 1953 syn. nov.) from Belgium are designated. The species is redescribed and illustrated, and a differential diagnosis is given. The former designation of a holotype, paratypes and paratypoids by Jung is invalid because it was not published. In addition, a problem with Tonnoiriella obtusa (Tonnoir, 1919) comb. nov. (= Tonnoiriella anchoriformis Salamanna, 1975 syn. nov.) from Belgium is resolved. A female specimen is designated as a lectotype, but only the dissected wings from this specimen are in condition suitable for redescription. There is additional non-type material collected later by Tonnoir; this material, including 3 females and 1 male, was the basis for redescription, illustrations and differential diagnosis. The unpublished male lectotype designated by Jung is invalid. Two species are added to the last checklist of Psychodidae from Belgium, raising the total number to 94.

Simple Summary Questions on how features of aquatic invertebrates (e.g., size, feeding style, respiration mode) evolve along a gradient of flow velocity, turbidity and elevation are rarely addressed. Furthermore, another outstanding question is what is the environmental condition in which an abrupt change occurs in terms of the compositions and abundance of these organisms' features. To answer the previous questions, we collected macroinvertebrates and measured the flow velocity, turbidity and elevation in the streams of the Guayas basin (Ecuador); subsequently, we analyzed the data. We observed that the abundance of most organisms' features increased with increasing flow velocity, while they decreased with increasing turbidity. Furthermore, there was a substantial drop in the abundance of tegument-respiring invertebrates beyond the turbidity of 5 NTU and an abrupt decline in the diversity of the organisms' features below 22 m above sea level, implying the need to focus water management in these altitudinal regions. Our results suggest that there is a need to implement measures that minimize erosion to alleviate turbidity that affects these organisms. The findings of our study provide a basis to determine critical targets for aquatic ecosystem management. Although the trait concept is increasingly used in research, quantitative relations that can support in determining ecological tipping points and serve as a basis for environmental standards are lacking. This study determines changes in trait abundance along a gradient of flow velocity, turbidity and elevation, and develops trait-response curves, which facilitate the identification of ecological tipping points. Aquatic macroinvertebrates and abiotic conditions were determined at 88 different locations in the streams of the Guayas basin. After trait information collection, a set of trait diversity metrics were calculated. Negative binomial regression and linear regression were applied to relate the abundance of each trait and trait diversity metrics, respectively, to flow velocity, turbidity and elevation. Tipping points for each environmental variable in relation to traits were identified using the segmented regression method. The abundance of most traits increased with increasing velocity, while they decreased with increasing turbidity. The negative binomial regression models revealed that from a flow velocity higher than 0.5 m/s, a substantial increase in abundance occurs for several traits, and this is even more substantially noticed at values higher than 1 m/s. Furthermore, significant tipping points were also identified for elevation, wherein an abrupt decline in trait richness was observed below 22 m a.s.l., implying the need to focus water management in these altitudinal regions. Turbidity is potentially caused by erosion; thus, measures that can reduce or limit erosion within the basin should be implemented. Our findings suggest that measures mitigating the issues related to turbidity and flow velocity may lead to better aquatic ecosystem functioning. This quantitative information related to flow velocity might serve as a good basis to determine ecological flow requirements and illustrates the major impacts that hydropower dams can have in fast-running river systems. These quantitative relations between invertebrate traits and environmental conditions, as well as related tipping points, provide a basis to determine critical targets for aquatic ecosystem management, achieve improved ecosystem functioning and warrant trait diversity. This research was performed in the context of the VLIR Ecuador Biodiversity Network project. This project was funded by the Vlaamse Interuniversitaire Raad—Universitaire Ontwikkel-ingssamenwerking (VLIR-UOS), which supports partnerships between universities and university colleges in Flanders and the South.

The Rwenzori Mountains and Albertine Rift region of southwestern Uganda are part of a globally recognized biodiversity hotspot, but are currently facing pressures from intensified agriculture, mineral exploitation and hydroelectric power generation. This study was undertaken to assess the ecological water quality of Rwenzori rivers using biomonitoring metrics to determine the major factors shaping macroinvertebrate community structure in disturbed and undisturbed sites. We sampled macroinvertebrates at 66 sites along headwater tributaries and downstream areas of the Nyamwamba, Mubuku and Nyamugasani rivers, supplemented by five sites along the Kazinga channel and Lake George wetland, and identified a total of 32,579 macroinvertebrates to family level. Insecta was the most diverse taxon (45 families). Based on Average Score Per Taxon (ASPT) scores, sites were classified into four ecological water quality groups as excellent (40 sites), good (16), fair (7) and poor (8). Upstream sites had the highest abundance of pollution-sensitive families such as Caenidae and Hydropsychidae, while downstream sites had high numbers of Chironomidae. Lorenz curves revealed a low degree of evenness with Gini coefficient values ranging from 0.75 to 0.94. Ordination analysis revealed that total phosphorus, specific conductivity, chloride and chemical oxygen demand were key environmental variables contributing to variation among the sites. The majority of sites did show little to no anthropogenic influence with the exception of downstream sites. The results of this study provide useful baseline reference data, to assess and better manage the impacts of anthropogenic activities on the ecological integrity of the region’s aquatic systems. Furthermore, these datasets will advance the development of a regional family-level biotic index.

Riparian forest buffers have multiple benefits for biodiversity and ecosystem services in both freshwater and terrestrial habitats but are rarely implemented in water ecosystem management, partly reflecting the lack of information on the effectiveness of this measure. In this context, social learning is valuable to inform stakeholders of the efficacy of riparian vegetation in mitigating stream degradation. We aim to develop a Bayesian belief network (BBN) model for application as a learning tool to simulate and assess the reach- and segment-scale effects of riparian vegetation properties and land use on instream invertebrates. We surveyed reach-scale riparian conditions, extracted segment-scale riparian and subcatchment land use information from geographic information system data, and collected macroinvertebrate samples from four catchments in Europe (Belgium, Norway, Romania, and Sweden). We modelled the ecological condition based on the Average Score Per Taxon (ASPT) index, a macroinvertebrate-based index widely used in European bioassessment, as a function of different riparian variables using the BBN modelling approach. The results of the model simulations provided insights into the usefulness of riparian vegetation attributes in enhancing the ecological condition, with reach-scale riparian vegetation quality associated with the strongest improvements in ecological status. Specifically, reach-scale buffer vegetation of score 3 (i.e. moderate quality) generally results in the highest probability of a good ASPT score (99–100%). In contrast, a site with a narrow width of riparian trees and a small area of trees with reach-scale buffer vegetation of score 1 (i.e. low quality) predicts a high probability of a bad ASPT score (74%). The strengths of the BBN model are the ease of interpretation, fast simulation, ability to explicitly indicate uncertainty in model outcomes, and interactivity. These merits point to the potential use of the BBN model in workshop activities to stimulate key learning processes that help inform the management of riparian zones. Riparian forest buffers have multiple benefits for biodiversity and ecosystem services in both freshwater and terrestrial habitats but are rarely implemented in water ecosystem management, partly reflecting the lack of information on the effectiveness of this measure. In this context, social learning is valuable to inform stakeholders of the efficacy of riparian vegetation in mitigating stream degradation. We aim to develop a Bayesian belief network (BBN) model for application as a learning tool to simulate and assess the reach-and segment-scale effects of riparian vegetation properties and land use on instream invertebrates. We surveyed reach-scale riparian conditions, extracted segment-scale riparian and subcatchment land use information from geographic information system data, and collected macroinvertebrate samples from four catchments in Europe (Belgium, Norway, Romania, and Sweden). We modelled the ecological condition based on the Average Score Per Taxon (ASPT) index, a macroinvertebrate-based index widely used in European bioassessment, as a function of different riparian variables using the BBN modelling approach. The results of the model simulations provided insights into the usefulness of riparian vegetation attributes in enhancing the ecological condition, with reach-scale riparian vegetation quality associated with the strongest improvements in ecological status. Specifically, reach-scale buffer vegetation of score 3 (i.e. moderate quality) generally results in the highest probability of a good ASPT score (99-100%). In contrast, a site with a narrow width of riparian trees and a small area of trees with reach-scale buffer vegetation of score 1 (i.e. low quality) predicts a high probability of a bad ASPT score (74%). The strengths of the BBN model are the ease of interpretation, fast simulation, ability to explicitly indicate uncertainty in model outcomes, and interactivity. These merits point to the potential use of the BBN model in workshop activities to stimulate key learning processes that help inform the management of riparian zones.

Extensive anthropogenic activities including land conversion have been taking place in the Guayas river basin (Ecuador) due to increasing population growth. Land use changes are considered one of the key sources affecting the ecological water quality of the Guayas river basin. Therefore, we investigated the effect of land use on the ecological water quality both within direct vicinity and within a distance of 200 m from the sampling sites. We investigated which of three land use assessment methods (i.e. data retrieved from field protocols, from aerial pictures (Google maps) and from GIS data) is most suitable to quantify the impact of local land use on the ecological water quality and which key environmental variables influence the ecological water quality. To do so, we collected data on macroinvertebrates and environmental variables from 120 sampling sites throughout the river basin during an integrated sampling campaign. The Biological Monitoring Working Party adapted for Colombia (BMWP-Col) was calculated and used to assess the ecological water quality status of the river basin, based on macroinvertebrates. The relation between the BMWP-Col, local land use and other environmental variables was investigated using generalized linear models (GLMs) and sensitivity analyses. Based on multi-model comparison, the ecological water quality was best associated with the land use close to the sampling sites (field protocol, R2 = 0.93, p

Performing biological assessments of freshwater systems is crucial in most tropical rivers as the lack of in-depth knowledge about functional diversity inhibits the design of appropriate water management and restoration plans. Therefore, in this paper, we investigated the presence and evolution of the functional diversity of the macroinvertebrate community along a tropical river. More specifically, 31 locations were sampled in the Portoviejo River (Ecuador) and identified macroinvertebrates were assigned to one of the following functional feeding groups (FFGs): shredders, collector-gatherers, collector-filterers, scraper-grazers and predators. Results show that high fluctuations and relatively low similarity in functional feeding group composition occurred among closely located sites, suggesting the presence of local disturbances. Locations close to the effluent of a wastewater treatment plant show an extreme dominance of scraper-grazers, suggesting elevated nutrient input and algae growth. Further downstream, the interaction of upstream disturbances and local land use influenced the community composition. These interactions and the confirmation of the importance of land use on aquatic communities underline the fact that management should include both taxonomic and functional diversity.

Aquatic macroinvertebrates, 18 physical-chemical water characteristics and 30 hydromorphological variables were assessed at 85 locations on Leyte island, Philippines. Biological traits derived from literature were linked to the biological samples based on four different trait estimation methods. These data were used to determine the relation with river characteristics using negative binomial regression. At least five feeding habit modalities were associated with conductivity, velocity, pH, temperature, ammonium-N concentrations, and sediment. The various methods of estimating trait abundance differ in determined major patterns and ecological implications. Therefore, the estimation method used should be explicitly described in trait-related papers to avoid misinterpretation. Trait abundance-environment relationships can be linear or non-linear and therefore a careful selection of the functional relationship should be performed. The process of extracting knowledge from data is of paramount importance as relevant ecological insights were extracted providing insights on flow, wastewater and nutrient management in the rivers.

We evaluated the biological water quality in relation to chemicals discharged through sewage outfall during both dry and rainy season. The lowland area of the Cuenca River basin in the southern Andes of Ecuador, including the city of Cuenca, constituted the study area. To perform an integrated water quality assessment, data were collected of macroinvertebrates, physicochemical conditions and morphological characteristics in 43 sites in the Cuenca River and its tributaries. The Andean Biotic Index (ABI) and the Biological Monitoring Working Party adapted to Colombia (BMWP-Col) were used to evaluate the biological water quality. Both biological indexes were higher upstream than downstream from the city. Moreover, these indexes indicated better conditions during the rainy season than in the dry season, based on the presence of more sensitive families. The biological indexes related more to the oxygen saturation than to the five-day biological oxygen demand (BOD5), nutrients and chloride concentrations. The relationship between BOD5 and nutrient concentrations with the variation of both biological indexes was clearer in the dry season than in the rainy season. However, in some sites, these indexes were influenced more by morphological aspects than by pollutants. Both biological indexes showed similar patterns along the rivers, generally the BMWP-Col scored higher than the ABI index. The latter index was shown to be more suitable for the high Andes region. These results could be used to support the implementation of river restoration actions, such as determining priorities for splitting sewer and precipitation water transport systems and needs for improved wastewater treatment facilities in specific locations. © 2018 Elsevier GmbH

This study aims to assess the macroinvertebrate communities, diversity and ecological quality (expressed as BMWP-Viet) of rivers on a tropical island. Environmental factors associated with macroinvertebrate communities, diversity and ecological quality were identified to assist conservation planning and management. Biological (macroinvertebrates), chemical, physical and hydromorphological characteristics of 85 river reaches were assessed in Leyte island, Philippines. Canonical Correspondence Analysis (CCA) and multivariable linear regression (LRM) were performed to relate environmental variables and macroinvertebrates. Several taxa of snails, shrimps, dragonflies, beetles, bugs and caddisflies were found on the island. Although many sites had good to very good ecological quality and high diversity, about 41% had moderate to very bad ecological quality and low diversity. Based on CCA, we can conclude that macroinvertebrate communities were associated with velocity, sediment, conductivity and dissolved oxygen. Particularly, sensitive and tolerant taxa were encountered at high and low flow velocities, respectively. LRM indicated that macroinvertebrate diversity and ecological quality were associated with physical (turbidity), chemical (chlorophyll), hydromorphological characteristics (bank slope & pool/riffle class), habitat degradation (gravel/sand quarrying, erosion) and the presence of logs and twigs. Consequently, this study gives support to the use of invertebrates as indicators of certain environmental conditions and the results of this investigation can serve as a basis to set up dedicated experiments to further prove the causality of these discovered relations. Strikingly, organic pollution, as reflected by biological oxygen demand and chemical oxygen demand, was in general weakly related to invertebrate composition, diversity and ecological quality. This might be linked to the low input in most sites and the relatively short rivers which are closely connected to the marine system. Thus, typical midstream and downstream systems were not encountered and the accumulation of these pollutants along the river is less likely. Although the island is situated in the western Pacific Ocean and encounters intensive natural disturbances (severe typhoons), the taxa (families) are similar to other tropical systems and the effects of the environmental conditions are comparable. Findings of this study are valuable in understanding tropical island systems and provide insights into the effects of environmental conditions on stream invertebrates, which aids in protecting and conserving tropical insular systems.

Water quality modelling is an effective tool to investigate, describe and predict the ecological state of an aquatic ecosystem. Various environmental variables may simultaneously affect water quality. Appropriate selection of a limited number of key-variables facilitates cost-effective management of water resources. This paper aims to determine (and analyse the effect of) the major environmental variables predicting ecological water quality through the application of fuzzy models. In this study, a fuzzy logic methodology, previously applied to predict species distributions, was extended to model environmental effects on a whole community. In a second step, the developed models were applied in a more general water management context to support decision and policy making. A hill-climbing optimisation algorithm was applied to relate ecological water quality and environmental variables to the community indicator. The optimal model was selected based on the predictive performance (Cohen’s Kappa), ecological relevance and model’s interpretability. Moreover, a sensitivity analysis was performed as an extra element to analyse and evaluate the optimal model. The optimal model included the variables land use, chlorophyll and flow velocity. The variable selection method and sensitivity analysis indicated that land use influences ecological water quality the most and that it affects the effect of other variables on water quality to a high extent. The model outcome can support spatial planning related to land use in river basins and policy making related to flows and water quality standards. Fuzzy models are transparent to a wide range of users and therefore may stimulate communication between modellers, river managers, policy makers and stakeholders.

The Portoviejo River, located in the central western part of Ecuador, has been heavily impacted by damming, intensive agriculture and untreated wastewater discharge. Unfortunately, detailed information on the water quality and the ecological status of the Portoviejo River is not available, inhibiting decision-making and the development of water management plans. Therefore, the aims of this study were (1) to assess the ecological water quality, (2) to investigate the point along the environmental gradient where the most significant change in macroinvertebrate community occurs and (3) to find potential macroinvertebrate taxa that significantly change in abundance and frequency of occurrence along the Portoviejo River. To this end, macroinvertebrate and physico-chemical data were collected and hydro-morphological conditions were recorded at 31 locations during the dry season of 2015. The results showed that the ecological water quality of the sampling sites ranged from good to bad. In addition, the Threshold Indicator Taxa ANalysis was used to examine changes in macroinvertebrate communities and revealed significant community change points for sensitive taxa declining at a conductivity value of 930 (mu S.cm(-1)) and nitrate-nitrogen concentrations of 0.6 mg.L-1. In addition, the thresholds estimated for tolerant taxa were set at a conductivity value of 1430 mu S.cm(-1) and nitrate-nitrogen concentration of 2.3 mg. L. Atyidae, Corbiculidae, Thiaridae, Acari, Baetidae and Leptohyphidae can be considered indicator taxa, showing shifts in the community. This study suggests that values of conductivity and nitrate-nitrogen concentrations should not exceed the threshold levels in order to protect macroinvertebrate biodiversity in the Portoviejo River.

The Guayas river basin is one of the major watersheds in Ecuador, where increasing human activities are affecting water quality and related ecosystem services. The aims of this study were (1) to assess the ecological water quality based on macroinvertebrate indices and (2) to determine the major environmental variables affecting these macroinvertebrate indices. To do so, we performed an integrated water quality assessment at 120 locations within the river basin. Biological and physical–chemical data were collected to analyze the water quality. Two biotic indices were calculated to assess the water quality with an ecological approach: the Biological Monitoring Working Party Colombia (BMWP-Col) and the Neotropical Low-land Stream Multimetric Index (NLSMI). Both the BMWP-Col and NLSMI indicated good water quality at the (upstream) forested locations, lower water quality for sites situated at arable land and bad water quality at residential areas. Both indices gave relevant assessment outcomes and can be considered valuable for supporting the local water management. A correspondence analysis (CA) applied on both indices suggested that flow velocity, chlorophyll concentration, conductivity, land use, sludge layer and sediment type were the major environmental variables determining the ecological water quality. We also suggested that nutrient and pesticide measurements are important to study water quality in the area where intensive agriculture activities take place. The nutrient levels detected in agricultural areas were relatively low and illustrated that the types of crops and the current cultivation methods were not leading to eutrophication. The applied methods and results of this study can be used to support the future water management of the Guayas river basin and similar basins situated in the tropics.

Food production often leads to environmental degradation. Consequently, insights into ecosystem functioning in relation to exploitation are needed as a basis for socioeconomically acceptable mitigation of these impacts. A Bayesian Belief Network (BBN) model is developed to link three major ecosystem services (ES), i.e. food production, water provision and ecotourism, and determine the effect of local agricultural practices and management on the ES in the Guayas Basin (Ecuador). Several data sources were integrated into the BBN model, including processed spatial data from primary and secondary sources, sampling and survey data, and expert knowledge. The model suggests that banana and sugar cane generate the highest yield but provide low ecotourism benefits. In contrast, cacao produces the lowest yields but contributes to better water quality. Scenario analyses suggest that environmental gains are possible by optimising the land use (LU) based on the edaphoclimatic requirements of crops. Moreover, the integration of LU optimisation with upscaling and farming intensification can allow for additional advantages in water provision and ecotourism while mitigating productivity losses. The BBN development approach can serve as a reference for other case studies, where data scarcity plays a limiting factor in the assessment of interactions between key ES.

The growth of urbanization worldwide has contributed to the deterioration of the ecological status of water bodies. Efforts at improving the ecological status have been made either in isolated form or by means of integrated measures by stakeholders, but in many cases, these measures have not been evaluated to determine their benefit. In this study, we implemented a scenario analysis to restore the ecological water quality in the Cuenca River and its tributaries, which are located in the southern Andes of Ecuador. For this analysis, an integrated ecological model (IEM) was developed. The IEM linked an urban wastewater system (IUWS) model, which gave satisfactory results in its calibration and validation processes, with ecological models. The IUWS is a mechanistic model that incorporated the river water quality model, a wastewater treatment plant (WWTP) with activated sludge technology, and discharges from the sewage system. The ecological status of the waterways was evaluated with the Andean Biotic Index (ABI), which was predicted using generalized linear models (GLMs). The GLMs were calculated with physicochemical results from the IUWS model. Four scenarios that would enhance the current ecological water quality were analyzed. In these scenarios, the inclusion of a new WWTP with carbon, and with carbon and nitrogen removal as well as the addition of retention tanks before the discharges of combined sewer overflows (CSOs) were assessed. The new WWTP with carbon and nitrogen removal would bring about a better restoration of the ecological water quality due to better nitrogen removal. The retention tanks would help to enhance the ecological status of the rivers during rainy seasons. The integrated model implemented in this study was shown to be an essential tool to support decisions in the Cuenca River basin management.

In this study, we assessed the relationship between the occurrence of the invasive water hyacinth ( Eichhornia crassipes ) and water quality properties as well as macroinvertebrate diversity in a tropical reservoir, situated in western Ecuador. Macroinvertebrates and physico-chemical water quality variables were sampled at 32 locations (during the dry season of 2013) in both sites covered and non-covered by water hyacinth in the Daule-Peripa reservoir. The results indicated that, in terms of water quality, only turbidity was significantly different between sampling sites with and without water hyacinth (Mann–Whitney U -test, p U -test, p

Recent studies on water quality in tropical rivers indicate substantial differences between seasons. However, investigations on the needs and added value of season-specific models are lacking. Thus, this paper aims to determine the accuracy and relevance of season-specific and season-overarching models to predict biological water quality. Additionally, we investigated the variation of prediction accuracy using sub-datasets from different parts of the Cuenca River basin. This study was accomplished in the rivers that pass through the urban and suburban areas of the city of Cuenca, which is located in the southern Andes of Ecuador. The Andean Biotic Index (ABI) was used as an indicator of biological water quality. Subsequently, models were developed to predict the ABI, with physicochemical and morphological variables as predictors, which were collected in 43 sites during both the dry and the rainy seasons. The predictions were obtained using three kinds of generalized linear models (GLMs): Gaussian, Gamma and Inverse Gaussian. The season-specific models were more accurate than the season-overarching models. Similarly, the predictions of the biological water quality in sites sampled in the urban area were more accurate than the forecasts performed in reference sites. The major variables predicting the ABI during the dry season were five-day biological oxygen demand (BOD5), ammonium and orthophosphate, while dissolved oxygen (DO), oxygen saturation (OS), nitrate, total solids proved to be important during the rainy season. The results of this research emphasize the importance of developing season-specific models and the implementation of different key actions for river restoration during both the dry and rainy seasons. The accuracy and the replication of these models could be improved and checked with more data taken from new sampling events. The modelling approach developed in this study can be applied to similar basins in the tropics and reveals that environmental investments need to count on monitoring strategies and data and analyses of the biological water quality variation in dry and rainy seasons, within the context of sustainable development.

Worldwide, large investments in wastewater treatment are made to improve water quality. However, the impacts of these investments on river water quality are often not quantified. To assess water quality, the European Water Framework Directive (WFD) requires an integrated approach. The aim of this study was to develop an integrated ecological modelling framework for the River Drava (Croatia) that includes physical-chemical and hydromorphological characteristics as well as the ecological river water quality status. The developed submodels and the integrated model showed accurate predictions when comparing the modelled results to the observations. Dissolved oxygen and nitrogen concentrations (ammonium and organic nitrogen) were the most important variables in determining the ecological water quality (EWQ). The result of three potential investment scenarios of the wastewater treatment infrastructure in the city of Varaždin on the EWQ of the River Drava was assessed. From this scenario-based analysis, it was concluded that upgrading the existing wastewater treatment plant with nitrogen and phosphorus removal will be insufficient to reach a good EWQ. Therefore, other point and diffuse pollution sources in the area should also be monitored and remediated to meet the European WFD standards.

To assess the ecological water quality in Flanders (northern part of Belgium), macroinvertebrates have been collected by the Flemish Environment Agency. During the present study, the blackflies collected between 1997 and 2009 were identified to species level. In total, more than 44,000 specimens were identified, belonging to 12 different species. Sensitive species were restricted to small brooks, while species tolerating lower oxygen concentrations and higher nutrient concentrations were also present in larger watercourses. Several species were either restricted to watercourses in the Campine region (northeast Flanders) or the loamy region (southern Flanders), while the other regions only contained eurytopic species. The prevalence of blackflies increased from less than 5% to almost 30% in the nineties, but did not further increase during the next decade. Habitat suitability models (logistic regressions, artificial neural networks, support vector machines and classification trees) could accurately predict the presence or absence of blackflies. An ensemble forecast, based on predicted oxygen and nutrient concentrations due to planned water quality improvement strategies, predicted that blackflies prevalence will rise to 42% in 2015 and 64% in 2027. Since blackflies only possess a moderate sensitivity, they could occur in all types of running waters with a good water quality. As a good ecological status is required by the European Union Water Framework Directive for all surface waters, it is thus apparent that more efforts will be needed to improve the water quality in Flanders.

Stoneflies are macro-invertebrates that are sensitive water quality indicators. Here, their occurrence was modelled based on physical–chemical water characteristics, river morphology and land use with five different modelling techniques. In a case-study in Flanders, stoneflies were found in 219 samples and two sets of absence data were gathered: 219 random samples from sites without stoneflies and 219 samples from sites downstream of each sampling site where stoneflies were observed. With both random and downstream absences, logistic regressions, artificial neural networks, support vector machines, random forests and classification trees could all successfully predict stonefly occurrence. For most environmental parameters, significant differences were found between sites with and without stoneflies. As stoneflies were only detected in a few percent of the samples, the ecological water quality is obviously still too low in most watercourses. Based on planned water quality improvement measures, an ensemble forecast using the five mentioned modelling techniques predicted that stonefly prevalence will only increase marginally by 2015 and 2027. To meet the European Union Water Framework Directive requirements, which states that all surface waters should obtain a good ecological quality, a more ambitious management plan is needed to decrease nutrient concentrations and improve habitat quality.

To date, approaches in environmental risk assessment (ERA) are based on taxonomy-based descriptions of ecosystems. Due to the widespread occurrence of numerous types of chemicals in the environment and ensuing environmental risks, there is a need to get insight in the relationship between the response of the ecosystem to pollution and the characteristics (traits) of the organisms. The main hypothesis of the present research is that the trait composition of macroinvertebrate communities changes in a consistent manner along general environmental disturbance gradients. In this study, the relationship between maximal body length of macroinvertebrates and environmental variables (e.g. Cu concentration) reflecting river sediment quality in Flanders (Belgium) was analysed. It was found that the abundance at almost all body lengths decreased with a decreasing quality of the river sediment, which could be associated with a decrease in abundance of macroinvertebrate taxa. It was also observed that the number of different body lengths decreased with increasing pollution, which can be linked to a decrease in diversity of the macroinvertebrate community. At low levels of general environmental pollution especially small taxa ( 60 mm) decreased. The trend observed for general environmental pollution was further analysed for specific types of metal contamination. Basic and zero-inflated Poisson models showed that with increasing copper pollution, the abundance of larger taxa quickly decreased and only relatively small taxa remained abundant. However, the observed trend was not generally applicable for all contaminants. The results of this research indicate that by using only individual metal concentrations it is not possible to explain the shifts in size distribution of macroinvertebrates. Including other environmental characteristics and other traits could enhance the understanding of how the macroinvertebrate community composition responds to environmental disturbances.

When forecasting invasions, models built on a dataset from a certain region often have to be used for simulations in another geographic region. Results on the reliability and usefulness of such models are missing in literature. The present study compares habitat suitability models for the invasive amphipod species Dikerogammarus villosus developed based on data gathered in recently invaded rivers and channels in Flanders (Belgium), with similar models developed on the basis of long-term colonised systems in Croatia. The models were tested on their reliability in both regions. Two techniques, logistic regressions (LR) and classification trees (CT) were used to analyse the habitat preference of this species based on physical–chemical and morphological habitat characteristics. It was found that in Flanders, D. villosus prefers rivers with a non-natural bank structure, high oxygen saturation, low conductivity and good chemical water quality, which could be related to its distribution in large rivers and canals. In Croatian rivers, high oxygen saturation was the most important prerequisite for the species to be present. Despite the longer history of invasion in Croatia, the species seemed to have similar habitat preferences in both invaded regions. Both data-driven approaches yielded similar results, but CT performed somewhat better based on the used performance criteria (% Correctly Classified Instances, Kappa and Area Under Curve) and were easier to interpret compared to the LR. The CT models developed based on the data of Flanders performed moderately when applying on the data of Croatia, but had a lower performance when applied vice versa. The LR models did not perform well when applying on a dataset of another geographic area. Extrapolation of the logistic regression model seemed to be more difficult compared to classification tree models. Our results indicate that it is possible to determine the habitat preference of an invasive species and that these models could be applied to other regions in Europe in order to take preventive measures to control the further spread of invasive species. However, a major concern is that the models are developed based on a representative range of all relevant variables reflecting the stream conditions and that accurate data are important.

Logistic regressions, artificial neural networks, support vector machines, random forests and classification trees were used to predict habitat suitability for mayflies on basis of physical–chemical water characteristics, dominant land use type and structural parameters. As a case-study, the dataset of Flanders was used, which consisted of 4289 samples containing mayflies (presences) and 3315 samples from waters where mayflies were never encountered (absences). For all techniques, data were randomly divided in a training set (two thirds) and a test set (one third). Models were calibrated using a tenfold cross-validation on the training set and subsequently validated using the test set. All techniques delivered good models that were able to discriminate sites with and without mayflies and performance (expressed as percent correctly classified instances and kappa-statistics) was in all cases similar for the training and the test set. Artificial neural networks and random forests performed slightly better compared to the other techniques. Samples with mayflies contained significantly more oxygen, a better developed river structure, higher values for sinuosity and steeper slopes, while samples without mayflies had significantly higher values for ammonium, nitrite, Kjeldahl nitrogen, total phosphorous, orthophosphate, biological and chemical oxygen demand, pH and conductivity. Also land use differed significantly, with mayflies usually present in forests but absent in industrial areas. The prevalence of mayflies gradually increased during the nineties from about 20 to 40%, which corresponded with an improvement of the chemical water quality. During the last decade, however, water quality did not further improve and as a result, mayflies prevalence did not continue to increase. Based on the planned measures, an ensemble forecast using the five mentioned modelling techniques predicted that mayflies prevalence will increase to 46% by 2015 and to 72% by 2027. To meet the requirements of the European Water Framework Directive, which states that all surface waters should obtain a good ecological quality, extra efforts will be needed to decrease nutrient concentrations and to improve habitat quality.

The Gilgel Gibe reservoir, which was built to fulfill the energy demand and the electricity export ambitions of Ethiopia, was characterized by low macroinvertebrate diversity mainly due to water level fluctuations, trampling of the littoral zone by cattle, nutrient input, and siltation from the catchment flow. The downstream river system was also affected by the dam due to a strongly decreased discharge as the water is diverted to Gilgel Gibe II hydropower plant through a 25 km underground tunnel. The study was based on seasonal macroinvertebrate sampling, water quality analyses, measurement of daily water level fluctuation, and recording of major anthropogenic activities. Hierarchical cluster analysis and canonical correspondence analysis were performed to determine relationships between the macroinvertebrate community composition and the environmental variables in the reservoir. The cluster analysis, Kruskal-Wallis ANOVA, and MANOVA permutation tests, revealed that differences in physicochemica...

The aim of this study was to predict the future distribution of an invasive macroinvertebrate species, Dikerogammarus villosus, under changing environmental conditions. For this, we used an integrated modelling approach. First, a habitat suitability model (HSM) was constructed on the basis of a regression tree model, to determine the preferred chemical water quality conditions. Subsequently, this HSM was combined with a chemical water quality model that makes predictions on future water quality scenarios for the year 2015 and 2027. It was expected that the area of suitable habitat of D. villosus would increase with improving water quality conditions in the future. Finally, migration speed was incorporated to model the spatial–temporal spread of D. villosus based on a network analysis. On the basis of monitoring data of Flanders (Belgium), it was calculated that D. villosus is able to spread with an average speed of 5 km year−1.The model simulations indicate that the species is primarily present in large rivers and canals with a good chemical water quality. With improving water quality, the species will be able to colonize additional watercourses, mainly because of a decrease in chemical oxygen demand and orthophosphate concentration. A validation based on the observed occurrence shows that the model accurately predicts areas with a high suitability that are most likely to be invaded by D. villosus. Our integrated modelling approach is useful as a practical method to perform risk assessment for watercourses that are vulnerable to invasions not only in Flanders but also in the whole world. Copyright © 2013 John Wiley & Sons, Ltd.

Macroinvertebrates have been collected in Flanders since 1989 by the Flemish Environment Agency to assess ecological water quality. During the present study, the collected waterbugs were identified to species level. In total, more than 90 000 waterbugs were identified, belonging to 45 species. Two of these are recent additions to Flemish fauna: Sigara iactans was found to be a common species in 1989, the first year of monitoring, which is earlier than the first records reported so far, whereas Cymatia rogenhoferi remains a very rare species. Five different communities could be recognized: (1) species occurring in alkaline waters with a high pH, (2) species occurring in colder waters that can tolerate slightly brackish and nutrient rich water, (3) species from running waters, (4) species from acidic waters and (5) ubiquist species that occurred in all types of water. Owing to the general improvement of chemical water quality during the last decade, most species increased, however, three pollution tolerant species declined significantly: Callicorixa praeusta, Corixa punctata and Sigara striata.

SUMMARY 1. Water quality monitoring data from 10 watercourses and laboratory mesocosm studies were used to assess the potential impacts of the crustacean amphipod invader Dikerogammarus villosus on resident macroinvertebrate assemblage structure in Central European fresh waters. 2. The presence of D. villosus was associated with a decline in the prevalence of many native species, pollution sensitive as well as pollution tolerant, and changes in biotic indices, despite the trends of improved water quality coinciding with the invasion period. A general increase in the prevalence of other invaders was also noted. The potential impacts of D. villosus were substratum dependent, differing between stone, concrete and sand-dominated sites. 3. Mean Multimetric Macroinvertebrate Index Flanders (MMIF) values were marginally lower when D. villosus was present (P < 0.06), as opposed to when other amphipod species or no amphipods were present, despite the improved water quality. Mesocosm studies showed that several macroinvertebrate taxa were completely eliminated in treatments with D. villosus, oligochaete worms, Caenidae mayfly, chironomids and tipulids being particularly vulnerable to D. villosus predation. Biological Monitoring Working Party (BMWP) scores were lower in mesocosms with D. villosus as opposed to the native Gammarus pulex or no amphipods at all. 4. We predict that resident macroinvertebrate assemblages in both Central Europe and Britain will come under increasing pressure as D. villosus invasions progress. Consequently, macroinvertebrate biotic indices, such as the MMIF or BMWP, may need to be revised to account for changes in taxa sensitivities to water quality as well as increased predation and competition.

The Ponto-Caspian amphipod species Echinogammarus trichiatus (Martynov, 1932) was found in Belgium for the first time in June 2009 at two different locations in an artificial lake bordered by two large canals. Adults as well as juveniles were found in small numbers and occurred together with several other Ponto-Caspian species such as Dikerogammarus villosus (Sowinsky, 1894) and Dreissena polymorpha (Pallas, 1771). An identification key to the genus Echinogammarus of inland waters in Western Europe is provided. This first record of yet another new amphipod invader in Belgium demonstrates the continuous introduction of alien species into West European waters.

The focus of the present study was to investigate the mechanisms for the alleviation of Cu toxicity in plants by coexistent cations (e.g. Al(3+), Mn(2+), Ca(2+), Mg(2+), H(+), Na(+), and K(+)) and the development of an electrostatic model to predict 50% effect activities (EA50s) accurately. The alleviation of Cu(2+) toxicity was evaluated in several plants in terms of (i) the electrical potential at the outer surface of the plasma membrane (PM) (Ψ(0)(°)) and (ii) competition between cations for sites at the PM involved in the uptake or toxicity of Cu(2+), the latter of which is invoked by the Biotic Ligand Model (BLM) as the sole explanation for the alleviation of toxicity. The addition of coexistent cations into the bulk-phase medium reduces the negativity of Ψ(0)(°) and hence decreases the activity of Cu(2+) at the PM surface. Our analyses suggest that the alleviation of toxicity results primarily from electrostatic effects (i.e. changes in both the Cu(2+) activity at the PM surface and the electrical driving force across the PM), and that BLM-type competitive effects may be of lesser importance in plants. Although this does not exclude the possibility of competition, the data highlight the importance of electrostatic effects. An electrostatic model was developed to predict Cu(2+) toxicity thresholds (EA50s), and the quality of its predictive capacity suggests its potential utility in risk assessment of copper in natural waters and soils.

Macroinvertebrates were sampled in the Chaguana river basin in SW Ecuador in the wet season (March) and the dry season (September) of 2005 and 2006. To assess the robustness of several biological indicators, correlations were calculated between both years and between the wet and the dry season. In addition, it was tested if the indices gave significantly different results for sites with a bad, poor, moderate and good ecological water quality. Composition measures performed poorly in most cases, however, abundance, diversity and richness measures often performed better and tolerance measures, the so-called biotic indices, performed very well, even indices developed for temperate regions. By using pruned multitarget clustering trees, it was possible to predict several well-performing ecological water quality indices simultaneously on the basis of the occurring key macroinvertebrate taxa or, alternatively, on the basis of key environmental variables. In contrast to unpruned trees, which resulted in complex trees that were difficult to interpret and performed inferiorly, pruning resulted in transparent trees. Water quality indices scored high when Hydropsychidae were present and even higher when in addition also Megapodagrionidae were present. When no Hydropsychidae nor Libellulidae were present, the indices reached the lowest scores. However, this model based on key taxa occurrences did not perform well during validation. Water quality indices scored higher with increasing dissolved oxygen concentrations and a strong current velocity. The latter model based on environmental variables also performed well during validation. In the presented study, the ecological water quality could thus be accurately predicted solely on the basis of dissolved oxygen concentration and current velocity. It can therefore be concluded that multitarget clustering trees can be easily used as a practical tool for cost-effective decision support by water quality managers.

Polder lakes in Flanders are stagnant waters that were flooded by the sea in the past. Several of these systems are colonized by exotic species, but have hardly been studied until present. The aim of the present study was: (1) to assess the influence of exotic macrobenthic species on the outcome of the Multimetric Macroinvertebrate Index Flanders (MMIF) and (2) to use classification trees for evaluating to what extent physical–chemical characteristics affect the presence of exotic species. In total, 27 mollusc and 10 macro-crustacean species were present in the monitored lakes of which respectively five and four were exotic. The exclusion of the exotic species from the MMIF resulted in a significant decline of this ecological index (−0.03 ± 0.04; p = 0.00). This elimination often resulted into a lower ecological water quality class and more samples were classified into the bad and poor ecological water quality classes. Single-target classification trees for Gammarus tigrinus and Potamopyrgus antipodarum were constructed, relating environmental parameters and ecological status (MMIF) to the occurrence of both exotic invasive species. The major advantages of using single-target classification trees are the transparency of the rule sets and the possibility to use relatively small datasets. However, this classification technique only predicts a single-target attribute and the trees of the different species are often hard to integrate and use for water managers. As a solution, a multi-target approach was used in the present study. Exotic molluscs and crustaceans communities were modelled based on environmental parameters and the ecological status (MMIF) using multi-target classification trees. Multi-target classification trees can be used in management planning and investment decisions as they can lead to integrated decisions for the whole set of exotic species and avoid the construction of many models for each individual species. These trees provide general insights concerning the occurrence patterns of individual crustaceans and molluscs in an integrated way.

In Flanders (Belgium), treatment systems based on constructed wetlands have been successfully implemented to treat the liquid fraction of separated pig manure, resulting in water that meets the stringent discharge criteria. As these systems have proven their nutrient removal performance, attention has moved towards the concept of biodiversity development from a perspective of Integrated Constructed Wetlands (ICWs). The spontaneous colonization of constructed wetlands with macroinvertebrates was examined to quantify the added biological value presented by a farmyard treatment wetland. In total, 17 taxa were found. The diversity of macroinvertebrates increased along the water treatment path in the system and was higher in summer than in autumn. Several pollution sensitive taxa like Orthetrum, Ischnura, and Cloeon were found at the last basins of the treatment wetland chain. Most species were insects, since their adults can easily aerially colonize these recently constructed systems. Water quality was assessed using the Multimetric Macroinvertebrate Index Flanders (MMIF), and showed a general increase towards the end of the treatment. The MMIF increased significantly with decreasing nutrient levels. ICWs adequately combine the treatment of wastewater with supporting and enhancing biodiversity in agricultural landscapes.

The macrocrustacean community of brackish polder waters in Flanders was investigated based on a twenty year survey comprising 430 biological samples taken at 218 different locations. A clear shift in the gammarid community could be observed. After its introduction, the alien Gammarus tigrinus, originating from North America, reached high abundances and became widely spread in the polder waters within a few years. Simultaneously, a decrease in the prevalence of the indigenous brackish water gammarids G. duebeni and G. zaddachi occurred. However, at the same time a decrease in the salinity of the polder waters also was observed. Uni- and multivariate data analysis revealed a clear difference in the environmental preferences of G. tigrinus, G. duebeni, and G. zaddachi. The alien species preferred lower salinities, lower orthophosphate concentrations, and a higher oxygen concentration compared to the two indigenous species. Besides the decrease in prevalence of the native gammarids, a decrease was also observed in prevalence of two other indigenous brackish water crustaceans: Palaemonetes varians and Neomysis integer. It appears that the decrease in salinity is the most important factor causing the decline of the indigenous gammarids and not the introduction of the alien G. tigrinus.

Macroinvertebrates were sampled from summer 2006 until spring 2008 in the Du River basin in subtropical northern Vietnam. Seventy taxa were identified, which were dominated by aquatic insects, with Diptera, Hemiptera, Ephemeroptera, and Odonata being the orders with the highest diversities. Overall, macroinvertebrate diversity was higher during the wet season at upstream sites, while wide river sites downstream showed a higher diversity during the dry season. Spatial and temporal variations in the macroinvertebrate communities were driven by hydromorphological characteristics and especially by water quality issues reflecting anthropogenic impacts in the river basin. Multivariate analyses using canonical correspondence analysis discriminated between pristine and impacted sites. The caddisfly family Hydropsychidae, the mayfly family Caenidae, and the dobsonfly family Corydalidae were reliable indicators of sites with good ecological status. A relatively small temporal variation was detected in the ...

Benthic macroinvertebrates were sampled in the Chaguana river basin in SW Ecuador in March (wet season) and September (dry season) of 2005 and 2006. Aquatic insects dominated the macrobenthos, with Trichoptera, Diptera, Ephemeroptera, Hemiptera and Odonata being the orders with the highest diversity and Ephemeroptera and Diptera being most abundant. No systematic differences in richness and abundance were observed between dry and wet seasons, which is in agreement with the literature. It is concluded that, in the neotropics, macroinvertebrates can probably be sampled for water quality assessments during the whole year: however, sampling soon after spates should be avoided. Using multivariate analysis, stations could be clustered into three groups based on their macroinvertebrate community composition: sites with low, intermediate and high human impact. Classification trees indicated that stations with low human impact had low conductivities, while stations with high conductivities were characterised as highly impacted if the dissolved oxygen concentration was low and intermediately impacted if the dissolved oxygen concentration was high. Classification trees also indicated that Leptophlebiidae (Ephemeroptera) were characteristic for sites with low impact; in sites with intermediate impact, this family was absent but Hydropsychidae (Trichoptera) were present; when both families were absent, impact was high.

In the present study, classification trees (CTs) and support vector machines (SVMs) were used to study habitat suitability for 30 macroinvertebrate taxa in the Du river in Northern Vietnam. The presence/absence of the 30 most common macroinvertebrate taxa was modelled based on 21 physical-chemical and structural variables. The predictive performance of the CT and SVM models was assessed based on the percentage of Correctly Classified Instances (CCI) and Cohen's kappa statistics. The results of the present study demonstrated that SVMs performed better than CTs. Attribute weighing in SVMs could replace the application of genetic algorithms for input variable selection. By weighing attributes, SVMs provided quantitative correlations between environmental variables and the occurrence of macroinvertebrates and thus allowed better ecological interpretation. SVMs thus proved to have a high potential when applied for decision-making in the context of river restoration and conservation management.

The spread of aquatic invasive species is a worldwide problem. In the aquatic environment, especially exotic Crustacea are affecting biodiversity. The amphipod Dikerogammarus villosus is such an exotic species in Flanders, which is rapidly spreading and probably has a serious impact on aquatic communities. The purpose of the present study was to make use of lab results, field data and modelling techniques to investigate the potential impact of this species on other macroinvertebrates. All types of prey that were used in predator–prey experiments ( Gammarus pulex , Gammarus tigrinus , Crangonyx pseudogracilis , Asellus aquaticus , Cloeon dipterum and Chironomus species) were consumed by D. villosus , especially species that were less mobile such as the Chironomus species. The presence of gravel somewhat reduced predation by providing shelter to the prey. Substrate preference experiments indicated that D. villosus preferred a stony substrate. Using decisions trees to construct habitat suitability models based on field observations, it could be concluded that D. villosus is mainly found in habitats with an artificial bank structure, a high oxygen saturation and a low conductivity, which corresponds with canals with a good chemical water quality. Moreover, a synecological classification tree, based on the abundance of the taxa present in the macroinvertebrate communities, indicated that the presence of D. villosus negatively affected the presence of the indigenous G. pulex . When the laboratory experiments and the field observations are combined, it can be concluded that D. villosus can seriously affect macroinvertebrate communities in Flanders.

From 2004 till 2008, Diplura were sampled at 96 localities in Belgium. Nine different species of Campodea were collected: Campodea fragilis Meinert 1865, Campodea lankesteri Silvestri 1912, Campodea lubbocki Silvestri 1912, Campodea meinerti Bagnall 1918, Campodea plusiochaeta Silvestri 1912, Campodea remyi Denis 1930, Campodea rhopalota Denis 1930, Campodea staphylinus Westwood 1842 and Campodea wallacei Bagnall 1918. The ordination technique non-metric multidimensional scaling indicated that pH and temperature/humidity were probably the most important variables determining species composition. However, it was remarkable that almost all combinations of species were encountered in the field, often even under the same stone. As no temporal segregations seem to take place, it remains unknown how these very similar species can occur together.

Controlled flooding of lowlands is considered as a potential water management strategy to minimize the risk of flooding of inhabited areas during high water periods. However, due to industrial activities, river water, sediments and soils are often contaminated with metals which may have adverse effects on the ecosystem's structure and functioning. Additionally, salinity may greatly affect the bioavailability and toxicity of metals present or imported into these systems. The effect of contaminated soils under different flooding and salinity exposure scenarios on the growth, reproduction and metal accumulation in the oligochaete Tubifex tubifex (Müller, 1774) were examined. In these bioassays metal contaminated soils were flooded with water of different salinities (0 and 3 psu), and tested after 0, 6 and 12 months of permanent inundation. We indeed found that inundation time had significant decreasing effects on Cu and Zn accumulation; although initial accumulation of Cu and Zn was higher in the previously unflooded soil at the start of the flooding treatment, these differences seem to disappear after 6 months of permanent inundation. Moreover, the complex interaction between substrate type and salinity suggests that redox potential is probably of major importance.

An acute Biotic Ligand Model (BLM) was developed to predict the effect of cobalt on the survival of the potworm Enchytraeus albidus, exposed in nutrient solutions added to acid washed, precombusted sand. The extent to which Ca2+, Mg2+ and Na+ ions and pH independently mitigate cobalt toxicity to E. albidus was examined. Higher activities of Ca2+, Mg2+ and H+ linearly increased the 14 d LC 5 0 Co 2 + (LC50 expressed as Co2+-activity) whereas Na+-activity did not. Stability constants for the binding of Co2+, Ca2+, Mg2+ and H+ to the biotic ligand (BL) were derived, i.e. log KCoBL=5.13, log KCaBL=3.83, log KMgBL=3.95 and log KHBL=6.53. It was calculated that at Co-concentrations corresponding to the 14d-LC50 value, 32% of the BL sites were occupied by cobalt. An initial validation of the applicability of this BLM in true soil exposure systems was performed by comparing observed and model-predicted 14 d LC50 s in a standard artificial soil and a standard field soil. By assuming pore water to be the only route of exposure and assuming equilibrium between pore water Co2+ and solid phase Co, which is predicted by the geochemical WHAM-Model 6, LC50 s (as mg Co kg−1 dry wt of soil) were predicted within an error of less than a factor two. Further validation in true soil exposures, combined with more detailed knowledge of Co binding to soil solid phases is needed, if this model is to be used as a tool for risk assessment and derivation of soil quality criteria for Co.

Despite growing concern about the potential adverse effects of elevated cobalt concentrations in the environment, hardly any toxicity data are available for terrestrial invertebrates. Therefore, chronic toxicity of cobalt was assessed for the springtail Folsomia candida. The 28-day EC50 for the reproduction of F. candida was 1480 mg Co/kg dry wt in standard artificial soil (OECD) and 409 mg Co/kg dry wt in standard field soil (LUFA 2.2). The difference in toxicity can be explained by the higher pH and cation exchange capacity which decreased cobalt bioavailability in the OECD soil. When expressed as pore water concentrations, 28-day EC50s were similar: 159 mg Co/L in OECD and 174 mg Co/L in LUFA 2.2, which corresponded with calculated Co2+ activities of 0.953 and 1.20 mmol/L, respectively. Although the presented data can be considered as a step forward in the assessment of the potential risk of cobalt in the terrestrial environment, more toxicity data for different species are needed to evaluate the environmental risk of cobalt in soils.

Because of long-term chemical processes, metal bioavailability in field soils decreases with time. Metal toxicity may, therefore, be overestimated if toxicity data with freshly spiked soils are used to derive soil quality criteria, a current practice. In the present study, effects of the long-term processes, called aging, on copper partitioning and ecotoxicity are investigated. Twenty-five field soils contaminated by copper runoff from bronze statues and 25 uncontaminated control soils sampled at 5-m distance from these statues were collected in Flanders (Belgium). The soils were selected so that parameters affecting copper bioavailability (pH, cation-exchange capacity, organic matter content, etc.) varied considerably. To assess the effect of aging on copper toxicity, control soils were spiked at total copper concentrations comparable to those of historically contaminated soils. Pore-water copper concentrations and 0.01 M CaCl2-extracted copper concentrations were significantly higher in freshly spiked soils compared to contaminated field soils. However, this could be a pH effect, because pH decreased after spiking. Acute toxicity to Enchytraeus albidus (14 d) as well as chronic toxicity to Folsomia candida (28-d reproduction) and Trifolium pratense (14-d growth) indicated a dose-response relationship between copper toxicity and pore-water copper concentration or the CaCl2-extracted copper fraction.

Springtails were sampled monthly with pitfall traps in the ancient Pb-Zn mining area of Plombieres for one year. Based on the total soil concentrations of lead, zinc, cadmium and copper, it was expected that zinc would probably have the most adverse effects on the populations. Activity and species richness of springtails were negatively related to the total zinc concentration in the soil, the water-soluble and the calcium chloride extracted zinc fractions. However, these relationships were only significant for the calcium chloride extracted fraction. The latter fraction might therefore be a good indicator of bioavailable zinc for springtails. Despite the high total soil concentrations of zinc, springtails were still quite abundant at all sampling sites. This is probably caused by the low bioavailability of zinc to the springtails in the soils of the study sites. (C) 2003 Editions scientifiques et medicales Elsevier SAS. All rights reserved.

Application of 5% (w:w) novel metal immobilizing agent reduced the water soluble, the calcium chloride extracted as well as the pore water concentration of zinc in soils from Maatheide, a metal contaminated site in the northeast of Belgium. Addition of the metal immobilizing agents also eliminated acute toxicity to the potworm Enchytraeus albidus and the earthworm Eisenia fetida and chronic toxicity to the springtail Folsomia candida. Cocoon production by E. fetida, however, was still adversely affected. These differences may be explained by the species dependent routes of metal uptake: F. candida is probably mainly exposed via pore water while in E. fetida dietary exposure is probably also important. From these results it is clear that organisms with different exposure routes should be used simultaneously to assess the environmental risk of metal contaminated soils.

Different extractable zinc fractions and the ecotoxicity of zinc in Enchytraeus albidus were assessed using freshly spiked artificial soils and spiked soils which had been aged for 8 weeks. Standard artificial Organization for Economic Cooperation and Development (OECD)-soils were aged in four different ways: (1) storing at 20 degrees C; (2) percolation followed by storing at 20 degrees C; (3) alternately heating at 60 degrees C and storing at 20 degrees C; and (4) alternately freezing at -20 degrees C and storing at 20 degrees C. Ageing had no clear influence on the pore water concentration, the water soluble and the calcium chloride extractable fraction of zinc in the artificial soils. Similarly, the 21d LC50 and the 42d EC50(reproduction) for E. albidus were not influenced by the different treatments. This absence of zinc fixation in the artificial soil during ageing was probably due to the use of kaolinite clay in OECD-soil.

Despite growing concern about the potential adverse effects of elevated nickel concentrations in the environment, only a few toxicity data are available for terrestrial invertebrates. Therefore, chronic toxicity of nickel was assessed for Eisenia fetida, Enchytraeus albidus and Folsomia candida, the three invertebrates for which standard test protocols are available. The 21 d EC50 for the cocoon production of E. fetida was 362 (241-508) mg Ni/kg dry wt. For the reproduction of E. albidus, a 42 d EC50 of 275 (217-346) mg Ni/kg dry wt was observed. The 28 d EC50 for the reproduction of F. candida was 476 (347-671) mg Ni/kg dry wt. The obtained toxicity data were very similar to those of related species reported in literature. Although the presented data can be considered as a step forward in the assessment of the potential risks of nickel in terrestrial environments, further research is needed to evaluate the influence of soil parameters on the toxicity of nickel and to quantify the effect of ageing on bioavailability.

Cadmium tolerance in Enchytraeus albidus was assessed for non-acclimatised organisms, as well as populations acclimatised for 18 months to 32, 100 and 320 mg Cd/kg dry wt. of standard artificial soil. Despite the increased concentration of metallothionein-like proteins in the acclimatised potworms, no changes in sensitivity to acute and chronic (juvenile production) cadmium toxicity could be observed. The 21-day LC50s ranged from 627 for the non-acclimatised enchytraeids to 748 mg Cd/kg dry wt. for the organisms acclimatised for 18 months to a cadmium concentration of 320 mg/kg dry wt. The 42-day EC50s varied from 96.2 (73.6-115) for the organisms acclimatised to 32 mg Cd/kg dry wt. to 234 (186-290) mg Cd/kg dry wt. for those acclimatised to 100 mg Cd/kg dry wt., while the value was intermediate for the non-acclimatised organisms and those acclimatised to the highest cadmium concentration. The elevated content of metallothionein-like proteins apparently only served for the detoxification of the increased cadmium body burdens.

Uptake and elimination kinetics of zinc and cadmium were studied in the oligochaetes Enchytraeus albidus and Eisenia fetida. Even at the highest exposure concentrations where E. fetida survived, the internal zinc concentration was still regulated to a constant level. Enchytraeus albidus could not regulate the internal zinc concentration as well, and the body burden increased after exposure to high zinc concentrations. After transfer to clean soil, the internal zinc concentration dropped back to the control level within a few weeks. For both species, internal cadmium concentrations did not reach equilibrium during the uptake experiments. The internal concentrations causing 50% reduction in cocoon production for E. fetida exposed to cadmium varied between different soil types, indicating that no fixed critical body burdens exist. For both zinc and cadmium, bioaccumulation factors decreased with increasing soil metal concentrations. Bioaccumulation factors may therefore be poor indicators of environmental risk. Their dependence on the total soil concentration makes bioaccumulation factors also unsuitable for assessing the influence of soil characteristics on the bioavailability of metals in contaminated field soils. For the same reason, uptake rate constants are probably not suited for this purpose.

Acute and chronic ecotoxicity tests with zinc were performed with the earthworm Eisenia fetida, the potworm Enchytraeus albidus, and the springtail Folsomia candida. To assess the influence of the soil type on zinc toxicity for these soil invertebrates, these tests were carried out in a standard artificial soil, a sandy and a loamy field soil. Based on the results of this experimental work and data taken from literature, models were developed relating the ecotoxicity of zinc to the most important parameters controlling bioavailability: pH and cation exchange capacity. Models were developed for E. fetida and F. candida using the regression technique partial least squares projection to latent structures (PLS). Acute as well as chronic toxicity data of both organisms could be normalized on the basis of the pH and the cation exchange capacity of the test soils. For other terrestrial invertebrates, not enough data were available to develop reliable models.

Carabid beetles were monthly sampled with pitfall traps in the ancient Pb-Zn mining area of Plombieres during one year. Based on the total soil concentrations of lead, zinc, cadmium and copper, it was expected that zinc would probably have the most adverse effects on the populations. Activity and species richness of carabid beetles were, however, not significantly correlated with total zinc concentration nor with the water soluble and the calciumchloride extractable concentration. In fact, despite the high soil concentrations, carabid beetles did not seem to be affected in the study area. The apparent lack of effects at the high observed zinc concentrations is probably caused by the low bioavailability of zinc to the beetles in the litter of the study sites which was also reflected in the low observed water soluble zinc concentrations.

During a year-round pitfall sampling campaign on twelve inland dunes in eastern Flanders, a total number of thirteen centipede species were caught. The encountered centipede fauna, with Lithobius calcaratus as the most ubiquitous species, was related to that of the Campine region that is also characterized by acid sandy soils. Community analysis on the basis of species composition revealed that the woody stations had a higher species diversity than the more open heath lands and moss dunes. Brachygeophilus truncorum and Cryptops hortensis were most characteristic for the woody stations whereas Lamyctes fulvicornis and Lithobius microps were more common in the open sites.