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The importance of flow‐related factors to benthic organisms, as well as the role of habitat conditions in shaping aquatic communities during low‐flow periods, have been recognised. Despite this, the preferences of macroinvertebrates to the ratio of lentic to lotic habitats at the reach scale have not been accurately quantified in most instances.Aquatic invertebrates and habitat features in a range of temporary rivers in Sardinia were investigated. The investigation focused on the flow‐related characteristics that contribute to defining the lentic–lotic condition of the river reaches. The relation of habitat features to benthic taxa distributions was assessed using multidimensional scaling. The main aim of the paper was to quantify the responses of taxa to the different lentic and lotic habitat conditions by applying hierarchical logistic regressions. Finally, taxon optima were aligned along the lentic–lotic gradient and the responses of different taxonomic groups compared.Unbroken waves and imperceptible flow were correlated with benthic taxa variability, suggesting local hydraulics and turbulence have a major role in regulating community composition. The overall lentic–lotic character of the river reaches was also clearly related to the benthic taxa distribution. More than 80% of taxa were significantly related to the lentic–lotic gradient, and an asymmetrical response curve was the predominant model.Benthic groups showed taxon optima clustered in different ranges of the lentic–lotic gradient. Odonata, Coleoptera, Hemiptera, and Mollusca preferred clearly lentic conditions. Diptera mainly ranged on the lotic side of the gradient, while Trichoptera were relatively uniformly distributed across the gradient. Ephemeroptera taxa clustered in intermediate lentic–lotic conditions, with two species preferring extremely lentic habitats. In general, optima converged at intermediate and extremely lentic conditions, presumably due, respectively, to the coexistence of different lentic and lotic features and to the highly diverse environmental characteristics under extremely lentic situations.These results support the conclusion that dissimilar ecological factors act on benthic taxa along the lentic–lotic range and species favouring different lentic–lotic conditions are subjected to pressures of different nature. This should not be ignored when defining species preferences and studying community structure or relationships between species in Mediterranean rivers, which cyclically vary their habitat composition. In addition, the uneven distribution of optima of different groups along the lentic–lotic gradient might affect macroinvertebrate metrics when assessing ecological status or establishing reference conditions under variable climatic conditions. [ABSTRACT FROM AUTHOR]

This study investigated temporal changes in the vertical distribution of invertebrates during periods of low flows in the Tafna wadi, a semi-arid Mediterranean river characterised by a general decline in average flows. The hyporheos was sampled along a 130-m stretch at depths of 0.3, 0.6 and 1 m in a pool-riffle sequence and a lateral gravel bar. Benthic fauna was collected on each sampling occasion from different locations in the studied sections. Sampling was conducted in two consecutive years (2014 and 2015) at the end of the spring (high waters) and over a 2-month period during the low summer flow. The results indicated that high surface water temperatures may initiate the movement of some taxa into the interstitial habitat, thus supporting the hyporheic refuge hypothesis. In the hyporheic zone, the low oxygen rates recorded deeper in the sediment and in the last low-flow months caused significant declines in taxonomic richness, and lower pH values resulted in a reduction in invertebrate abundances. In the benthic zone, high flow velocities increased richness but decreased invertebrate abundances. A large number of taxa were found in the gravel bar section reflecting the more suitable living conditions in this habitat compared with the river reach (high DO rates). [ABSTRACT FROM AUTHOR]

This study aims to determine whether the benthic meiofaunal assemblages on the intertidal zone of Danshuei River estuary (DRE) in Taiwan vary from the estuary to the upper stream, and in response to different habitats. A total of six major taxa (Nematoda, Copepoda, Ostracoda, Polychaeta, Oligochaeta and Gastrotricha) of meiofauna and 44 nematode genera were recorded at 12 sampling stations in DRE in October, 2013. Meiofauna densities ranged between 4.67 ± 2.08 and 294.00 ± 180.40 ind./10 cm2, the average was 162.31 ± 84.36 ind./10 cm2. Nematodes were the dominant group (relative abundance, RA: 89.27%) in the meiofaunal community at all stations, with its assemblage in DRE dominated by nonselective deposit feeders (55.14%). There were striking differences in nematode assemblages between mangroves and mangroves with reed habitats. Pearson's correlation analysis showed that the dominances of the genera Anoplostoma, Metacylicolaimus and Deontostoma were significantly negative while Terschellingia correlated positively with salinity. These genera showed either decreasing or increasing trends at stations from the estuary to the upper stream. The dominances of the genera Megadesmolaimus and Theristus were significantly positively correlated with the proportion of sand and negatively correlated with the proportion of silt and clay. Our results indicate that salinity and sediment type influenced nematode assemblages in the DRE. [ABSTRACT FROM AUTHOR]

The aim of this research was to investigate the diversity patterns of benthic insects and functional feeding groups by assessing the contribution of α and β diversity components over 1 year. Temporal diversity variation as a function of the diversity components and regional rainfall in subterranean streams was also verified. Diversity components varied significantly at different spatial scales. In general, α diversity tended to be smaller and less varied temporally than the β diversity components. In addition, we detected a higher contribution of β2, indicating the importance of the regional species pool. Finally, for all significant models relating diversity values with rainfall, the relationship was negative. Intense flows leached organisms, leading to homogenization of communities. On the other hand, despite this negative effect, each functional feeding group responds differently to the hydrological stress, which makes it difficult to develop community predictability models after a disturbance. [ABSTRACT FROM AUTHOR]

This study was carried out to evaluate the variation of diversity and composition of benthic insects in streams, along an altitudinal gradient in an arid area of Belezma National Park, Northern East of Algeria. Benthic entomofauna was sampled in the spring season of 2015, 2017 and 2018 at 28 sampling sites distributed along 4 streams unaffected by human pressure. The altitudinal gradient varies between 1045 m and 1500 m. At each site, we measured 5 physicochemical parameters of water and other physical factors describing each site (velocity, depth and width). All of these environmental factors vary significantly with altitude. A total of 78 taxa belonging to 55 families and 8 orders of benthic insects were identified. Both diversity and abundance of studied entomofauna vary with altitudinal gradient. The highest values of diversity were found in the fourth altitudinal zone (AZ4: up to 1400 m, total taxa richness = 52) and AZ3 (1300 to 1400 m, Shannon index = 3.16). The average number of individuals in AZ1 is higher than in all the other altitudinal zones (mean individuals number = 102.75). The General Linear Model analysis shows that the altitudinal gradient is in favour of high diversity but in disfavour of population abundance. The hierarchical clustering analysis revealed three cluster groups of benthic insects, which are altitudinal indicators. Diptera and Ephemeroptera in downstream stations are mainly replaced by Coleoptera in upstream ones. [ABSTRACT FROM AUTHOR]

Aquatic macroinvertebrates are widely used as bioindicators for water quality assessments involving different kinds of disruptive factors, such as hydrological regime variations or pollutant spills. Recently, they demonstrated to be effective in monitoring effects of climate change in alpine stream and rivers. Indeed, since the distribution of macroinvertebrates in glacier-fed streams has been succesfully investigated and described by several authors, the discrepancy in presence/absence and quantity of specific taxa from the established models may represent an early warning of the effects of climatic changes occurring in alpine riverine ecosystems. New information Together with the present paper, we provide a dataset covering a period of 6 years (2010-2015) sampling of aquatic macroinvertebrates along a longitudinal transect of a glacier-fed stream located in the Italian Alps, inside the International Long Term Ecological Research (ILTER) macrosite of Matsch|Mazia (IT-25). Data were collected during the glacial melt period (April - September), with monthly resolution. Owing to the unique temporal resolution of the dataset, we aim to produce a reliable tool (i.e. reference point) for future ecological assessment on the same stream, but also to similar streams worldwide. [ABSTRACT FROM AUTHOR]

The biodiversity of glacier-fed streams is particularly threatened by climate change, emphasising the need of monitoring these sentinel systems. The glacier-fed Saldur stream is an International Long Term Ecological Research (ILTER) site in the Italian Central Eastern Alps. Here, we sampled benthic macroinvertebrates and measured environmental variables (discharge, suspended solids, conductivity, water temperature, and channel stability) five times at six sites (5-11 km from the glacier) during an entire glacial melt season (April-September). Our main objectives were (1) to elucidate relationships between the abiotic variables and the faunal composition, (2) to quantify and compare the spatial and temporal variability of the faunal community, and (3) to assess the composition of the benthic macroinvertebrate community in relation to conceptual models. Hosting a higher number of individuals and more diverse communities at sites with reduced glacial influence, the Saldur stream fitted well in the framework of conceptual models. Nevertheless, the spatial variability of the fauna was higher than the temporal variability. This study presents an initial characterisation of the benthic faunal assemblages in the Saldur stream, constituting a reference point for future analyses dealing with potential disruptive factors introduced by climate change and upcoming hydroelectric power production on this stream. [ABSTRACT FROM AUTHOR]

Rivers are a vital resource for human wellbeing. To reduce human impact on water bodies, the European Union has established an essential regulatory framework for protection and sustainable management (WFD; 2000/60/EC). In this strategy, reliable and economic bioindicators are a fundamental component. Benthic macroinvertebrates are the group most commonly used as bioindicators through all European countries. However, their conventional assessment currently entails serious cost-efficiency limitations. In this study, we have tested the reliability of metabarcoding as a tool to record river macroinvertebrates using samples from a mock community (in vitro validation) and eDNA extracted for field validation from water from six sites within a north Iberian river (River Nalón, Asturias, Spain). Two markers (V4 region within the nuclear 18S rDNA and a fragment of the mitochondrial COI gene) were amplified and sequenced using an Illumina platform. The molecular technique has proven to be more sensitive than the visual one. A cost-benefit analysis shows that the metabarcoding approach is more expensive than conventional techniques for determining macroinvertebrate communities but requires fewer sampling and identification efforts. Our results suggest metabarcoding is a useful tool for alternative assessment of freshwater quality. [ABSTRACT FROM AUTHOR]

We selected streams located in north-eastern Brazil with the objective of assessing the effect of streams of different orders (1st, 2nd, 3rd) on the distribution and composition of benthic macroinvertebrates in the rainy and dry seasons. A total of 12822 individuals and 62 taxa of benthic macroinvertebrates were obtained, of which Chironomidae was the taxon with the most individuals (60.08% of the total). The benthic macroinvertebrate assemblage ordination demonstrated that streams of the 3rd order had a different assemblage structure compared to streams of the 1st and 2nd order. This distinction may be the result of taxa substitution. The benthic macroinvertebrate assemblage structure was correlated with environmental variables. In conclusion, the variation of the environmental characteristics according to stream order was the most important factor in benthic macroinvertebrate assemblage organisation and replacement of taxa in the streams investigated. [ABSTRACT FROM AUTHOR]

Rivers are a major source of microplastic particles (<5 mm) to oceans, but empirical measurements of microplastic movement in freshwater ecosystems are rare. The hard, buoyant surface of microplastic is a novel habitat that selects for unique microbial assemblages in rivers, especially downstream of wastewater treatment plant (WWTP) point sources. We measured microplastic in surface water and benthic habitats 50 m upstream and 50, 305, 1115, and 1900 m downstream of the effluent outfall from a large WWTP in an urban river. We used high-throughput sequencing to measure bacterial assemblages on microplastic from surface and benthic habitats and compared them to bacterial assemblages from seston, water, and sediment. Concentrations of total microplastic and microplastic types (fragment, pellet) in surface water did not change with distance downstream of the WWTP. Thus, microplastic transport showed no net deposition or resuspension. Microplastic concentrations were much higher in the benthic zone than surface water. Benthic deposition appears to be a plastic sink over longer time scales, but subsequent studies are needed to resolve microplastic transport dynamics by particle type, size, and habitat. Composition of microplastic-attached bacterial assemblages differed from that of assemblages in water, seston, and sediment and supports domestic wastewater as a point source of microplastic (e.g., gastrointestinal taxa). Shifts in microplastic assemblages with distance from the WWTP suggest succession toward a 'stream-like' bacterial assemblage. Future studies are required to quantify the metabolic capacity of microplastic-associated bacteria. Estimates of transport distance, microplastic storage, and microbial interactions are critical to include lotic ecosystems in accountings of global plastic budgets. [ABSTRACT FROM AUTHOR]

We used the trait composition of macroinvertebrate communities to identify the effects of pesticides and multiple stressors associated with urban land use at different sites of four rivers in Spain. Several physical and chemical stressors (high metal pollution, nutrients, elevated temperature and flow alterations) affected the urban sites. The occurrence of multiple stressors influenced aquatic assemblages at 50% of the sites. We hypothesized that the trait composition of macroinvertebrate assemblages would reflect the strategies that the assemblages used to cope with the respective environmental stressors. We used RLQ and fourth corner analysis to address the relationship between stressors and the trait composition of benthic macroinvertebrates. We found a statistically significant relationship between the trait composition and the exposure of assemblages to environmental stressors. The first RLQ dimension, which explained most of the variability, clearly separated sites according to the stressors. Urban-related stressors selected taxa that were mainly plurivoltine and fed on deposits. In contrast, pesticide impacted sites selected taxa with high levels of egg protection (better egg survival), indicating a potentially higher risk for egg mortality. Moreover, the trait diversity of assemblages at urban sites was low compared to that observed in pesticide impacted sites, suggesting the homogenization of assemblages in urban areas. [ABSTRACT FROM AUTHOR]

Although the Erfelek Stream is a small stream with a total length of 80 km and a flood discharge of 302.1 m3/sec, from its source to the place where it merges with the sea. It is ecologically very important for its immediate environment in terms of the zonations created by it and the groups of living organisms it contains. The fact that it is the only stream that reaches the sea by forming a delta between the Kızılırmak and Filyos Stream and that it reaches the sea by drawing meanders in the delta after different geological formations it passes through starting from an altitude of 1370 meters allows it to be a stream rich in biodiversity. Karagöl, which is connected with the sea, which is almost destroyed within the delta, and the Aksaz wetlands, which are still continuing their existence increase the importance of the stream in terms of both aquatic products and other groups of living organisms. In the fauna and flora of the Erfelek stream, the presence e few benthic invertebrate, fish, birds, mammals and plant species have been identified up to now. On this study, the importance of biodiversity and ecology of Erfelek Stream is aimed to be revealed as a result of present data and preliminary observations. [ABSTRACT FROM AUTHOR]

Recognition of the deteriorating conditions of rivers worldwide has called for increased efforts to improve the ecological quality of impacted river systems. This is particularly important in areas that have suffered from a significant impact of human pressure on the ecological status of water. Field studies were conducted in the Ruda River in an area that had undergone anthropogenic disturbances. The objectives of our survey were to test the biological metrics based on benthic macroinvertebrates at four study sites. Spring and autumn surveys of benthic invertebrates indicated that based on the BMWP and BMWP(PL) indices, water quality was higher in comparison with the value of Multimetric index at all of the sites that were studied. Our results revealed that the water quality was higher at the study sites that are located above the dam reservoir based on both the chemical and biological parameters. This study also indicated that both spring and autumn constitute appropriate periods for carrying out monitoring studies. The values of multimeric index indicated the same water quality (except for site 1) in both sampling periods. Anthropogenic transformations of a riverbed influence the flora and fauna and affect the ecological status of rivers. [ABSTRACT FROM AUTHOR]

We sampled different substrates (sand, gravel, leaf litter and stones) in the rainy and dry season to study the distribution and composition of benthic macroinvertebrates in tropical streams (northeastern Brazil). Benthic macroinvertebrates were distributed according to the substrates, with stones showing a higher richness and abundance of species and abundance of collector-gatherers and filter-collectors. The results of the PCoA showed a separation of stones from the other substrates and similarities between sand and gravel. [ABSTRACT FROM AUTHOR]

In order to assess the river habitat quality of Dongjiang river (Huizhou reach), we developed a hierarchical structure model, which including 12 indices in three aspects: river water habitat, riverside habitat and riverway habitat. An ordering relation method, improved by interactive decision making and index scale, was employed to determine index weight, and their importance. And based on grading 12 indices and river habitat quality, habitat quality of 15 investigation stations are assessed, and the relationship between habitat quality and water physicochemical indices, benthic animals and riparian land-used type has been analysed. [ABSTRACT FROM AUTHOR]

The presence of large wood (LW) in river channels adds an important habitat feature for benthic macroinvertebrates. However, there has been a lack of studies focusing on the effects of simple wood structures on hydromorphology and macroinvertebrate diversity in surrounding channel areas. This study explores whether consistent patterns in LW-related benthic habitat complexity and macroinvertebrate diversity can be identified across a set of low-gradient streams dominated by fine sediments. While the presence of LW did not change the average values of standard hydromorphological variables (flow velocity, turbulence, median sediment grain size and sorting index), the coefficients of variation of such variables for wood rich sites were consistently higher than those for wood poor sites (velocity: 85 % higher, turbulence: 89 %, grain size: 126 %, sorting index: 67 % higher). In parallel, beta diversity was on average 31 % higher in the wood rich sites, and positively correlated with the amount of LW at the site. The hotspots of local (alpha) diversity were located in the river-bed areas surrounding the LW, where taxonomic richness was 83 % higher and Shannon-Wiener diversity 39 % higher compared to the sites with less wood. These results demonstrate that the presence of LW in sandy lowland rivers induces consistent patterns of increased spatial variability of benthic habitats in the surrounding channel areas and this significantly enhances alpha and beta diversity of macroinvertebrate communities. Therefore, LW should be conserved in river channels wherever possible, and its potential for introduction into degraded systems should be explored further because even simple pieces of LW introduced to lowland streams can deliver benefits. [ABSTRACT FROM AUTHOR]

The responses of benthic macroinvertebrates to land-use-induced changes in water quality and habitat because of contrasting land-use types along the Umfurudzi River, Zimbabwe, were investigated in 2013. Five stations in a communal area upstream of Umfurudzi National Park, four on the edge of the park and six in the park were sampled monthly from April to July 2013 for physico-chemical variables and aquatic macroinvertebrates. Phosphates and siltation levels were significantly higher at stations in the communal area, compared to those in the park. Vegetation cover and conductivity were significantly higher at stations in the park compared to those in the communal area. Recovery of macroinvertebrate communities along a disturbance gradient from the highly disturbed, silted, low percentage vegetation cover communal area stations through the semi-disturbed park edge area to the less disturbed, less silted, high percentage vegetation cover stations in the park was demonstrated. Consequently, the management of tropical catchments should include practices that minimise loss of riparian vegetation and that guard against siltation of aquatic systems. The study also demonstrates the capacity of macroinvertebrates to act as indicators of these disturbances. [ABSTRACT FROM PUBLISHER]

Coal mining in central Appalachia USA causes increased specific conductance in receiving streams. Researchers have examined benthic macroinvertebrate community structure in such streams using temporally discrete measurements of SC and benthic macroinvertebrates; however, both SC and benthic macroinvertebrate communities exhibit intra-annual variation. Twelve central Appalachian headwater streams with reference quality physical habitat and physicochemical conditions (except for elevated SC in eight streams) were sampled ≤fourteen times each between June 2011 and November 2012 to evaluate benthic macroinvertebrate community structure. Specific conductance was recorded at each sampling event and by in situ data loggers. Streams were classified by mean SC Level (Reference, 17–142 μS/cm; Medium, 262–648 μS/cm; and High, 756–1535 μS/cm). Benthic macroinvertebrate community structure was quantified using fifteen metrics selected to characterize community composition and presence of taxa from orders Ephemeroptera, Plecoptera, and Trichoptera. Metrics were analyzed for differences among SC Levels and months of sampling. Reference streams differed significantly from Medium-SC and High-SC streams for 11 metrics. Medium-SC streams had the most metrics exhibiting significant differences among months. Relative abundances of Plecoptera and Trichoptera were not sensitive to SC, as the families Leuctridae and Hydropsychidae exhibited increased relative abundance (vs. reference) in streams with elevated SC. In contrast, Ephemeroptera richness and relative abundance were lower, relative to reference, in elevated-SC streams despite increased relative abundance of Baetidae. Temporal variability was evident in several metrics due to influence by taxa with seasonal life cycles. These results demonstrate that benthic macroinvertebrate communities in elevated-SC streams are altered from reference condition, and that metrics differ in SC sensitivity. The time of year when samples are taken influenced measured levels and differences from reference condition for most metrics. [ABSTRACT FROM AUTHOR]

The present paper presents a hydrobiological study of the Tur River catchment area, based on the qualitative structure of aquatic invertebrate communities coming from nine sampling sites, located on the main river course and on its main tributaries. There were investigated the upper and lower Tur River sectors, which includes four protected areas that lie on the lower Tur river course - ROSCI0214 (Tur River), ROSPA0068 (Lower Tur Floodplain), and within the Complex Reserve (The Tur River) the Nature Reserve (Lower Tur River) and the Nature Reserve "Pădurea Noroieni (Noroieni Forest)". Analyses on the composition and structure of the benthic invertebrate communities emphasized the differences between the investigated areas. [ABSTRACT FROM AUTHOR]

The assemblage of benthic macroinvertebrates in relation to some selected environmental variables of the two headwater streams of Aiba Reservoir was studied from May 2013 to March 2014. This was with a view to assessing the health status and water quality of the streams, and comparing their taxa richness with similar studies on the reservoir and its out-flowing stream. A total of 23 taxa were recorded in the study. NO3- and PO43 showed indirect relationships (P<0.05) with bioindicators of good water quality, while dissolved oxygen (DO) showed indirect relationship (P<0.05) with bioindicators of poor water quality. The streams were of poor biological water quality, and diversity indices revealed that they were polluted and unstable in habitat structure. Anthropogenic impacts at the upper reaches need to be mitigated and regular biomonitoring of the streams is of the essence, in order to conserve the integrity of the downstream reservoir. [ABSTRACT FROM AUTHOR]

We aimed to establish the effect of seasonal drought on leaf litter breakdown and invertebrate communities. Differences in breakdown rates of Nothofagus pumilio were experimentally compared using the litter bag method (coarse and fine mesh size bags) in two first-order streams, one intermittent and one perennial, during two different hydrological periods. Colonizing fauna found in coarse mesh bags was quantified, identified and compared with benthic biota from the same streams. Leaf litter decay rates in low flow conditions revealed that breakdown was principally a consequence of microbial action in the intermittent stream. In contrast, breakdown in high flow conditions was caused by invertebrate feeding in both streams. Collector-gatherers constituted most of the abundance and biomass in bags from the intermittent stream, due to their rapid benthic recolonization. Shredders peaked at approximately 50% remaining leaf litter mass in both streams only during high flow, which coincided with general models of detritus breakdown in streams. Considering global warming scenarios, with drought and water temperature increases expected for many regions of the world, these studies on the consequences for the biota and ecological processes of small streams will allow the prediction of negative effects on such vulnerable ecosystems. [ABSTRACT FROM AUTHOR]

Benthic macroinvertebrates are organisms primarily living in the streambed. The stability of the streambed is of vital importance to macroinvertebrate assemblages. Measurement of the streambed stability and sampling of macroinvertebrates were performed from 2005 to 2011 in four mountain streams: the Shengou, Diaoga, Jiangjia and Dabaini Rivers, which have different stability and are all located in the Yunnan plateau in southwestern China. The Shengou, Diaoga and Jiangjia Rivers are composed of gravels and cobbles, and the Dabaini River is mainly composed of gravels. The streambed stability was determined by the ratio of time over the sum of erosion and deposition areas of sediment per unit streambed width at each measured cross-section. The Shengou River had the highest stability, followed by the Diaoga and Jiangjia Rivers. The Dabaini River had the lowest stability. A total of 70 taxa of macroinvertebrates belonging to 45 families and 68 genera were identified in these streams. Arthropods were the dominant taxonomic group. Collector gatherers had the highest density. Taxa richness, Shannon-Weaver index and K-dominance curve were used to assess the biodiversity of macroinvertebrates. Results showed that the Shengou River had the highest biodiversity, followed by the Diaoga and Jiangjia Rivers. The Dabaini River had the lowest biodiversity. The detrended correspondence analysis ordination indicated that the streambed stability was the main factor that influenced macroinvertebrate assemblages, counting for 22.7% of the variance. The biodiversity and wet weight of the macroinvertebrates were highly dependent on the streambed stability. The biodiversity increased with the streambed stability and reached equilibrium when the stability was over 20 year m−1. The wet weight of macroinvertebrates showed an increasing trend with the streambed stability. However, no clear relation was identified between the density of macroinvertebrates and the streambed stability. It was concluded from this study that, in order to improve the ecological condition within the mountain streams, erosion and sedimentation must be controlled to enhance the streambed stability. Copyright © 2014 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Channel curvature and riffle-pool bathymetry in meandering streams control complex hydrodynamic and morphodynamic processes. This study investigates how spatial and temporal heterogeneities in flow hydraulics influence benthic fauna in a meander bend of a lowland sand-bed river. Spatial heterogeneity of riverbed morphology and secondary flow, induced by channel curvature, make pools hydraulically more diverse compared with riffles. Numerical simulations demonstrate that velocity reversal between riffles and pools in this meander bend produces spatially variable flow with complex temporal variations. Patterns of macro-invertebrates indicate an increase in population density from riffle to pool, reflecting an increase in diversity of abiotic factors. For most invertebrate species the observed patterns persisted during temporal variations of the flow. Considerable changes were observed only in some groups with specific preferences. [ABSTRACT FROM PUBLISHER]

Principal threats to running waters are linked to human-made discharge modifications, but tools to predict the quantitative consequences of flow restoration for benthic invertebrates in large rivers remain untested., Quantitative benthos samples from two bypassed reaches (Pierre-Bénite - PBE - and Chautagne - CHAU) of the French Rhône River were collected during four years each before and after minimum flow increases (from 10 to 100 m3 s−1 at PBE and from 10 to 50 m3 s−1 at CHAU). These samples provided observed ln-density changes for the 50 and 62 ( PBE and CHAU, respectively) most abundant taxa (typically species or genera). For about half of the 'model' taxa among them, distinct preference models for bottom shear stress categories were available from four reaches of the Upper Rhône River and from various German rivers. Linking these preference models with a statistical hydraulic model predicting frequencies of shear stress categories for any given discharge, we predicted ln-density changes of the model taxa after restoration., Community structure of the abundant taxa changed clearly and rapidly after restoration at PBE but less clearly at CHAU. Our predictions explained a considerable amount of mean ln-density changes of our model taxa observed after restoration (75 and 30% at PBE and CHAU, respectively). They also explained (67 and 40% at PBE and CHAU, respectively) the model taxa scores along the principal components analysis axis that summarised the community variations of all abundant taxa before and after restoration. For taxa not identified to species (assessed as genus, tribe or family), the predicted ln-density changes were sometimes inaccurate at PBE (a Lower Rhône site), suggesting that the transferability of preference models for taxonomic levels above that of species can be problematic., If further developed, statistical habitat models focussing on ecologically relevant physical variables (in our case shear stress) should enable reliable quantitative assessments of associations between flow restoration efforts and achievable ecological improvement. [ABSTRACT FROM AUTHOR]

We developed habitat suitability curves (HSC) using generalised additive models (GAMs) for nine benthic macroinvertebrate taxa from a small New Zealand river for hydraulic-habitat modelling assessments of instream flow requirements. We included interaction terms between the primary variables (water depth, velocity, substrate) when significant, to address a longstanding criticism of univariate HSC. To date, only large-river univariate HSC have been available and these have been used in hydraulic-habitat applications on small rivers, despite doubt over the transferability of HSC between rivers of different size and type. We tested the outcome on the predicted abundance–flow relationship of applying the small-river habitat suitability GAMs versus large-river GAMs for two taxa on the same small river. We found the effects of flow allocation were overestimated by the large-river GAMs relative to the small-river GAMs. Further research to develop general HSC for categories of river size and type is needed to better inform hydraulic-habitat modelling applications. [ABSTRACT FROM PUBLISHER]

In the last decades, hydromorphological degradation of rivers has gained more attention in river management, stressing the importance of understanding the links between hydromorphology and aquatic assemblages. The present study investigated general patterns in the response of benthic invertebrate assemblages to single morphological features along naturally diversified Slovenian rivers. The whole gradient of local habitat quality (river habitat quality, RHQ) and habitat modification (river habitat modification, RHM) features, according to the Slovenian hydromorphological assessment method, was covered. Regional natural characteristics explained the low share of RHQ and RHM variability, indicating nonregional presence of morphological features. The analysis identified predominant flow and predominant channel substrate as the most important RHQ features. We found that in contrast to RHQ features, RHM features had low explanatory power. These results suggest a weaker response of benthic invertebrate assemblages to the physical alteration itself than to the effect that the alteration exerts on habitat quality features. Variance partitioning among three environmental variable groups revealed predominantly independent effects (69%) on benthic assemblages, mostly on account of regional natural characteristics (30%) and RHQ features (31%). As benthic invertebrate assemblages are adapted to the former natural conditions, a similar modification may result in different effects with regard to regional natural differences. Therefore, the low proportion of variability, explained by RHM features, might be the consequence of joint dataset from different regions. Our study gives general implications for river management, but in order to more clearly define the significance of particular modification features, we suggest further analysis within more homogeneously defined habitats that encompass regional natural characteristics. Copyright © 2014 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Evolution of fish body shapes in flowing and non-flowing waters have been examined for several species. Flowing water can select for fish body shapes that increase steady swimming efficiency, whereas non-flowing water can favor shapes that increase unsteady swimming efficiency. Benthic stream fishes often use areas near the substrate that exhibit reduced or turbulent flow, thus it is unclear which swimming forms would be favored in such environments, and how shape might change across flow regimes. To test the relationship between fish body shape and flow regime in a benthic stream fish, we used geometric morphometric techniques to characterize lateral body shape in mountain sucker ( Catostomus platyrhynchus) across flow rates, using stream gradient as an indicator of stream flow. Mountain suckers from low-flow environments were more streamlined, consistent with steady swimming body shapes, whereas mountain suckers from high flows had deeper bodies, consistent with unsteady swimming body shapes. In addition, smaller individuals tended to have more robust body shapes. These patterns are opposite to those predicted for stream fishes in the mid-water column. The benthic stream environment represents a distinct selective environment for fish shape that does not appear to conform to the simple dichotomy of flowing versus non-flowing water. [ABSTRACT FROM AUTHOR]

Authors of several studies of the spatial distributions of microorganisms have shown strong geographical patterns and stressed the importance of considering the spatial component explicitly when studying assemblage-environment relationships. The processes underlying the patterns are still under debate because it is difficult to separate the unique roles of dispersal limitation and mass effects from spatially structured variation in environment. We analyzed correlations between assemblage dissimilarity and geographical and environmental distances in a large French diatom database, subdivided into regions, years, and different water-quality levels, with multiple regression on distance matrices (MRM) and partial Mantel correlograms. Before we applied MRM, we identified the strongest environmental predictors with the BIO-ENV procedure, which selects the best predictors after testing correlations between distance matrices including every possible set of variables. Environmental control of assemblages was stronger than spatial factors in explaining assemblage patterns, but purely spatial patterns also were significant at the national scale and within some regions. When we averaged environmental and biological data over 3 y, environmental variables accounted for more variability in assemblage structure than relationships estimated with data from a single year. Assemblages in mountainous regions showed particularly strong spatial patterns, perhaps because dispersal barriers hinder the exchange of colonists across sites. The strong spatial structure in the diatom data leads us to encourage researchers to divide ecoregions into smaller areas, especially in mountainous landscapes, when studying assemblage-environment relationships. We also recommend the use of averaged biological and environmental data when developing biotypologies of biotic assemblages for environmental assessment and conservation. [ABSTRACT FROM AUTHOR]

The Volga, the largest river in Europe, has experienced multiple stressors from human activities. Recently we showed that its upper course (about 500 km, from its source to Tver) still has large sections with low impact and a natural type-specific potamal flora and fauna. Our present research in the East European lowlands aim to define reference conditions for mid-sized to large lowland rivers in order to build a basis for future management and conservation. Three monitoring sites were selected based on the results from intensive sampling in 2005. In subsequent field campaigns between 2006 and 2010 regular surveys were carried out each year in summer and additional ones in spring. A taxon-rich macroinvertebrate fauna, including several rare potamal relict species, was recorded and the data was used to provide an overview of annual and interannual variation in community indices and metrics. The conditions described for the headwaters of the Volga River system can be used as a reference state for medium-sized and large lowland rivers in regions where reference sites of these types are lacking. [ABSTRACT FROM AUTHOR]

As a precursor to developing a biomonitoring program for rivers of the Coastal Hudson Bay Lowland, this study characterized and compared the benthic macroinvertebrate communities and water chemistry in 5 remote, previously undescribed, rivers near Fort Severn, Ontario, Canada. The pH of river water ranged from 8.1 to 8.7, total phosphorus from 11 to 26 μg L, dissolved organic carbon from 8 to 12 mg L, and chloride from 56 to 153 mg L. A total of 57 benthic macroinvertebrate taxa were represented, and the 10 most numerically dominant were the Chironominae (26 % of collected individuals), Orthocladiinae (16 %), oligochaetous clitellata (9 %), Hyalellidae (7 %), Hydropsychidae (6 %), Gammaridae (5 %), Elmidae (5 %), Sphaeriidae/Pisidiidae (4 %), Nemata (3 %), and Tanypodinae (3 %). Rivers' positions in ordinations of chemical and biological datasets were similar, suggesting that water chemistry has a role in structuring riverine benthic communities in the study region. Correlations between water-chemistry or habitat predictors and site-scores in the ordination of benthic macroinvertebrate taxa counts suggested that biological community structure was most associated with river-water pH, nutrient concentrations (e.g., total phosphorus, nitrogenous compounds, dissolved organic carbon, calcium, and silicate), the relative abundance of submerged macrophytes, conductivity (i.e., the concentrations of chloride and various other dissolved ions), and several geomorphological variables (e.g., bank-full river width, current speed, and the size of the dominant inorganic particles in the pavement layer of the streambed). Interest in mineral extraction and other resource-based exploration in Ontario's Far North is increasing. This study represents a start on baseline characterization for ecological monitoring and cumulative effects assessment that should proceed along with northern development. [ABSTRACT FROM AUTHOR]

The results of a study of zoobenthos and zooperiphyton of two rivers of the Ob’ River middle reaches are shown. A comparative analysis of the composition and abundance values of two ecological groups of zoobenthos and zooperiphyton hydrobionts has revealed the difference in their taxonomic compositions and dominant complexes. The similarity in total number and biomass of zoobenthos and zooperiphyton in the large river and the higher values of zooperiphyton quantitative development in a medium river have been identified. [ABSTRACT FROM AUTHOR]

Reduction of flow constitutes one of the most severe human alterations to rivers, as it affects the key abiotic feature of these ecosystems. While there has been considerable progress in understanding the effects of reduced flow on benthic macroinvertebrates, cascading effects of flow reduction on dissolved oxygen concentrations (DO) have not yet received much attention. We compared the macroinvertebrate composition between reference conditions and a situation after several years of discharge reduction in the Spree River (Brandenburg, Germany). Community composition shifted from rheophilic species to species indifferent to flow conditions. Filter feeders were partially replaced by collector/gatherers, which likely reduces the retention of organic matter, and thus the self-purification capacity of the river section. These shifts were associated with low discharge during summer, cascading into daily DO concentration minima of less than 5 mg l which prevailed 74% of the days in summer. This depletion of DO after flow reduction presumably caused the observed species turnover. Hence, flow reduction in lowland rivers may not only directly impair the ecological functions provided by benthic macroinvertebrates but may also act indirectly by depleting DO concentrations. [ABSTRACT FROM AUTHOR]

Dams alter the geomorphology, water quality, temperature regime, and flow regime of lotic systems influencing the resources and habitat of fish, benthic invertebrates, and lower trophic levels. Since the inception of the river continuum concept and the serial discontinuity concept (SDC), biotic and abiotic impacts below impoundments have been the focus of many lotic studies. However, recovery gradients below dams are rarely examined in sufficient detail and no current synthesis of longitudinal impacts in regulated rivers exists. This understanding is needed to build ecological relationships in regulated rivers to inform environmental flows science and management. In this review, we provide evidence for SDC predictions on physical, chemical, and biological recovery in regulated rivers. Additionally, we determine how these changes are reflected in the benthic community. Our review suggests that two recovery gradients exist in regulated rivers: (1) a longer, thermal gradient taking up to hundreds of kilometres downstream; and (2) a shorter, resource subsidy gradient recovering within 1-4 km downstream of an impoundment. Total benthic invertebrate abundance varies considerably, with both increases and reductions observed at near-dam sites and varying in recovery downstream. Much of this variability stems from the degree of flow alteration and resource subsidies from the upstream reservoir. In contrast, benthic diversity is often reduced below dams irrespective of dam location and operation with little recovery observed downstream. The community at near-dam sites is largely composed of filter-feeding invertebrates which are quickly replaced downstream, while stoneflies are reduced below impoundments with limited downstream recovery. Despite a lack of formal testing, studies support SDC predictions. The SDC still provides a useful theoretical framework for hypothesis testing, and future studies should further expand the SDC to include empirical estimation within the context of the landscape. [ABSTRACT FROM AUTHOR]

Hydromorphological deficits of European rivers and creeks are a major reason for the fact that the good ecological status stipulated by the European Water Framework Directive has not been achieved. In order to overcome these deficits, the German state of North Rhine-Westphalia calls for the implementation of a radiating effect concept to facilitate the planning of cost-effective restoration measures. The radiating effect concept states that natural or near-natural sections of water bodies have a positive impact on adjacent hydromorphologically altered sections. Transforming this concept into concrete measures will contribute to creating and boosting such radiating effects. We have applied the radiating effect concept to 11 small streams in a low mountain range and assessed its efficiency by comparing the biological and hydromorphological data of 48 sampling sites. Our findings show that near-natural stream sections have a positive effect on the ecological status of adjacent hydrornorphologically altered sections. This study provides an innovative approach to the implementation of Integrated River Basin Management at a local scale. Its results are potentially of major interest to water managers dealing with the challenge of prioritizing river restoration measures. Nevertheless, specific issues such as assessing the influence of artificial barriers limiting the radiating effects need to be further investigated. [ABSTRACT FROM AUTHOR]

35 qualitative macrozoobentonic samples were collected in 2011 from many Siret river tributaries coming from the Harghita Mountains (5 stations), Maramureş Mountains (14 stations), Moldavian Plateau (4 stations) and Vrancea Mountains (12 stations). Laboratory analysis of samples revealed the existence of the following 15 groups of benthic invertebrates: Ephemeroptera, Plecoptera, Trichoptera, Oligochaeta, Diptera (Chironomidae, Simuliidae, Ceratopogonidae, Limoniidae), Gastropoda, Bivalva, Coleoptera, Acarina, Odonata, Hirudinea, Isopoda, Heteroptera, Turbellariata and Collembola). Groups that have the highest frequencies were mayflies and dipterans (each with a frequency of 97.1%), followed by caddisflies (80%), amphipods (68.6%), oligochaetes (57.1%) and stoneflies (54.3%). Presence of sensitive groups to water quality degradation (Ephemeroptera, Trichoptera and Plecoptera) with high frequency shows good quality water at most stations investigated. [ABSTRACT FROM AUTHOR]

The flood pulse regime and the hydrological connectivity determine the lateral bidirectional exchanges of water, chemical compounds, and biota between the river and the floodplain habitats. The primary goal of the present research was to analyze the effect of water flow on macroinvertebrates in two water levels in a lateral connectivity gradient, from the main channel through a connection channel to a permanently connected lake. We tested the hypothesis that the water flow from the main channel to the floodplain habitats during high water level causes a decrease in beta diversity between the sites, increasing similarity in the system. To test this hypothesis, we sampled a river-floodplain-lake system of the Middle Parana' River during two water levels, and analyzed the spatial and temporal turnover of species between sites and habitats. Local physical characteristics, such as depth, benthic particulate organic matter, and grain size of bottom sediments influenced assemblage composition. Taxa richness, density, and Shannon diversity differed among habitats within the river-lake system, but did not show significant differences between water levels. Richness, density, and diversity were higher in the lake and the connection channel than in the Parana' River bank. Beta diversity was significantly higher during high water period. During low water period, benthic assemblage composition was homogenized, as reflected by the lower values of species turnover between the sites situated in the main channel-lake corridor during this phase. The lateral bidirectional exchanges among the habitats are essential for maintaining the specific invertebrate diversity of large river corridors. [ABSTRACT FROM AUTHOR]

The control of the quality of surface waters is very important for water resources management, especially in the aspect of the effective usage of river water. Many methods of water quality assessment are based on the results of hydro-chemical investigations. But these methods reveal the ecosystem's condition only for the given time period. Whereas, it is possible to assess the long-time period changes of the chemical and physical conditions of water with the help of bioindication methods. For the purpose of the ecological assessment of river Hrazdan the macrophytes and bottom community was investigated. As a result of the study it was revealed, that in the part before Yerevan the River Hrazdan is characterized as a β-mezosaprobe. Under the antropogenic load, there is high organic pollution after Yerevan (territory of Hovtashen village) and the water of river Hrazdan is characterized as α-mezosaprobe. [ABSTRACT FROM AUTHOR]

ABSTRACT Anthropogenic pressure on flow regimes has been recognized as a significant threat to the health of rivers in Canada and elsewhere. Yet while we know that the historical hydrological conditions prevailing at river sites can be assigned to runoff regime types, the implications of this hydrological structure on biological community composition have been poorly studied. Here we support the improvement of guidelines for flow management by exploring the relationship between biota and runoff regime types for selected rivers in British Columbia. One thousand six hundred biological samples were extracted from Environment Canada's Canadian Aquatic Biomonitoring Network (CABIN) database and a matching procedure was undertaken to associate biological samples to the long-term hydrometric monitoring stations stored in the HYDAT National Water Data Archive. A practical approach for spatial matching of hydrometric and biomonitoring sites was presented, which permitted matching of a sufficient number of samples to assess the structure of biological communities across the four regime types identified. By examining multivariate and univariate biological descriptors, including the recently developed Canadian Ecological Flow Index, differences in macroinvertebrate community composition between the runoff regimes were observed. In conclusion, we have developed a practical approach to match hydrological and biomonitoring data and we have forwarded guidelines on how to improve integration between hydrometric and biomonitoring networks. Moreover, we have provided the first ecological validation of runoff regime types in Canada, confirming the need to account for antecedent hydrological conditions in the assessment of ecological quality using biomonitoring data. Copyright © 2011 John Wiley & Sons, Ltd. and Crown in the right of Canada [ABSTRACT FROM AUTHOR]

Outflows from two atmospherically acidified lakes in the Bohemian Forest were studied in 2005 and 2007. While Lake Čertovo has been strongly acidified (∼pH 4.6), Lake Laka was only slightly acidified in the past and is recovering now (∼pH 5.2). The water chemistry and macrozoobenthos composition were analysed along longitudinal gradients of both lake outflows to determine the present status of their streams. A certain progression in stream chemistry to more neutral conditions was observed along the longitudinal gradients of both streams. However, a possible recovery of macrozoobenthos was evident only in the Lake Laka outflow, mainly via an increasing number of Ephemeroptera and Trichoptera taxa, and an increasing number of Gammarus fossarum, both along the longitudinal gradient and during the period of study. In contrast, no considerable changes were observed in the macrozoobenthos composition of the Lake Čertovo outflow, presumably because its chemistry was harmful for acidosensitive taxa such as Ephemeroptera and Trichoptera. Plecoptera and Chironomidae were the most numerous groups in this stream. The biological recovery of both streams will depend on further chemical improvement in their catchments as well as on the dispersal ability of benthic organisms. [ABSTRACT FROM PUBLISHER]

The impacts of watershed urbanization on streams have been studied worldwide, but are rare in China. We examined relationships among watershed land uses and stream physicochemical and biological attributes, impacts of urbanization on overall stream conditions, and the response pattern of macroinvertebrate assemblage metrics to the percent of impervious area (PIA) of watersheds in the middle section of the Qiantang River, Zhejiang Province, China. Environmental variables and benthic macroinvertebrates of 60 stream sites with varied levels of watershed urban land use were sampled in April, 2010. Spearman correlation analysis showed watershed urbanization levels significantly correlated with increased stream depth, width, and values of conductivity, total nitrogen, ammonia, phosphate, calcium, magnesium, and chemical oxygen demand for the study streams. There was significant difference in total taxa richness, Empheroptera, Plecoptera, and Trichoptera (EPT) taxa richness, and Diptera taxa richness, percentages of individual abundances of EPT, Chironomidae, shredders, filterers, and scrapers, and Shannon-Wiener diversity index between reference streams and urban impacted streams. In contrast, percentages of individual abundances for collectors, oligochaeta, and tolerant taxa, and biotic index were significantly higher in urban impacted than reference streams. All the above metrics were significantly correlated with PIA. The response patterns of total taxa richness, EPT taxa richness, and Shannon-Wiener diversity index followed a drastic decrease at thresholds of 3.6, 3.7, and 5.5% of PIA, respectively. Our findings indicate that stream benthic macroinvertebrate metrics are effective indicators of impacts of watershed urban development, and the PIA-imperviousness thresholds we identified could potentially be used for setting benchmarks for watershed development planning and for prioritizing high valued stream systems for protection and rehabilitation. [ABSTRACT FROM AUTHOR]

The goal of our study was to investigate the interaction between the invasive mussel and benthic invertebrate communities at different spatial scales and under different environmental conditions. We analyzed the effects of on benthic invertebrate communities at different downstream distances (meters) from mussel beds and compared these trends in 2 rivers characterized by dissimilar chemical disturbance levels. In areas distant from beds, invertebrate composition at the 2 rivers differed strongly, probably in response to different levels of environmental pollution. In areas near beds, invertebrate composition at the 2 rivers was similar, suggesting that golden mussels have strong homogenizing effects on faunal makeup. We also found that facilitation was species specific and, in contrast to the general paradigm, weaker (rather than stronger) under more stressful conditions. Our results show that understanding the effects of requires accounting for scale- and species-specific effects. [ABSTRACT FROM AUTHOR]

The article presents a study on the long-term trends in the response of benthic macrofauna to the hydrological conditions in the Lavaca-Colorado Estuary in Texas. The study included four stations representing a range of hydrography which were sampled from April 1988 to October 2008. The relationship between climate variability and local salinity patterns and benthic populations were investigated with the use of Oceanic Nino Index (ONI), North Atlantic Oscillation (NAO) and the North Pacific Index (NPI). The study suggested that the benthic macrofaunal communities are shaped by global climate variability and its effects on local salinity patterns and that there is no significant linear trend in temperature over time.

Natural hydrological variability in lotic ecosystems can include prolonged periods of flow recession. A reduction in discharge is accompanied by abiotic changes in benthic and hyporheic habitats, often including reductions in habitat availability. Whilst the benthic invertebrate community response to low flows is well documented, little research has considered how the composition of the community within the hyporheic zone is affected. We examined benthic and hyporheic invertebrate community composition during flow recession in a temperate karst stream, at sites with contrasting historic flow permanence regimes. Changes in benthic invertebrate community composition primarily reflected changes in habitat availability associated with discharge variability; in particular, the population density of the dominant amphipod, Gammarus pulex, increased as the area of submerged benthic sediments declined. Concurrent significant increases in the hyporheic abundance of G. pulex, and moderate increase in the proportion of the total G. pulex population inhabiting the hyporheic zone were recorded. It is postulated that G. pulex migrated into the hyporheic zone to reduce exposure to intensifying biological interactions in the benthic sediments. An increase in the hyporheic abundance of G. pulex was particularly pronounced at sites with historic intermittent flow, which could be attributed to downwelling stream water dominating vertical hydrologic exchange. The increase in G. pulex abundance reduced community diversity in the benthic sediments, but had no apparent detrimental effects on hyporheic invertebrate assemblages. Copyright © 2010 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

In August 2002, a heavy rainfall (445 mm in total for 5 consecutive days) resulted in a catastrophic flood, and it completely washed away the benthic fauna from the mainstream channel of the Gapyeong stream, a typical mid-sized stream in the central Korean peninsula. This study was to investigate the recovery patterns of aquatic insect communities that were damaged by the flood. Aquatic insects were sampled quantitatively using a Surber sampler (50 × 50 cm, 1 riffle and 1 pool/run habitats per site) from three sites (4th-6th order) of the Gapyeong stream prior to 2000 and seasonally after the flood event from 2003 to 2006. Before the flood in the reference year (2000), a total of 77 species of aquatic insects were collected, whereas after the flood 47 species (2003), 51 species (2004), 64 species (2005) and 55 species (2006) were collected from the whole sampling sites. The aquatic insect density decreased to 26.85% (2003), 90.25% (2004), 52.53% (2005) and 54.95% (2006) of that recorded in the reference year. Although approximately 70% of the aquatic insect fauna has recovered since the flood event, the species composition in the most recent year differed substantially (similarity ca. 50%). On the other hand, the compositions of functional groups have not significantly changed. Aquatic insect communities at the riffle sites were affected more profoundly than those at the pool/run sites. The aquatic insect communities at the upstream site recovered more rapidly than those at the downstream sites. [ABSTRACT FROM AUTHOR]

The article discusses the fish occurrence related to water temperature, fish size, and water flow on the lowland area in the fish pass of the River Elbe in Czech Republic in 2003-2004. It discusses the interaction of the fish species including roach, bleak, and gudgeon to the water temperature and flow. An overview of the rheophily of the fish or its bottom dwelling nature is also provided.

The article presents a study which aims to determine the life histories and life-cycle strategies of some invertebrates in intermittent streams in Hawke's Bay, New Zealand. The study was conducted from March 2005 to May 2007 in three different sites and used samples of various benthic macroinvertebrates including mayflies, caddisflies, and Potamopyrgus antipodarum snail. Results show that intermittent sites has more taxa, plurivoltine life cycles, and asexual reproduction than perennial sites.

Among-site variation in metacommunities (beta diversity) is typically correlated with the distance separating the sites (spatial lag). This distance decay in similarity pattern has been linked to both niche-based and dispersal-based community assembly hypotheses. Here we show that beta diversity patterns in community com- position, when supplemented with functional-trait information, can be used to disgnnse assembly processes. First, using simulated data, we show how the relationship between distance decay patterns in taxonomic and functional measures of community composition can be used to predict the influence of a given trait on community assembly. We then use the patterns generated by the simulation as a template to show that the sorting of benthic macroinvertebrate metacommunities in headwater streams is likely influenced by different sets of functional traits at regional and local scales. We suggest that functional-trait databases and spatially referenced taxonomic surveys can be used to predict the spatial scales at which different aspects of interspecific functional variation are involved in niche- based community assembly while accounting for the influence of dispersal-based community assembly processes. [ABSTRACT FROM AUTHOR]

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Since the nineteenth century, the mud snail Potamopyrgus antipodarum (Gray 1843), native to New Zealand, has been introduced into several European countries, Italy included. As a first step to contain its spread and establishment, it seems necessary to understand the characteristics of the environment that are more favourable for this species' invasion. To this aim, we analysed a number of physico-chemical and biotic parameters of four streams, two invaded and two not yet invaded, in the National Park of the Foreste Casentinesi, Monte Falterona, Campigna (Central Italy), where the species was first recorded in 2008. The two categories of streams, invaded and non-invaded, differ in only three of the 20 analysed characteristics of the habitat; that is, availability of crevices, width stream, and maximum water depth. This suggests that, despite P. antipodarum's documented tolerance to pollution, the high-quality waters of the park are highly susceptible to its invasion, if its vectors and pathways are not identified and adequately monitored. Most of the environmental parameters analysed in the studied streams were shown to be similar to those reported in the literature as preferred/tolerated by the species. Our findings pinpoint the vulnerability of nature reserves to species invasions, and call for more effective preventative measures. [ABSTRACT FROM AUTHOR]