Search

We assessed the temporal changes in and the relationships between the structures of the macroinvertebrate communities and the environmental conditions of the French Rhône River (the river from Lake Geneva to the Mediterranean Sea) over the last 20 years (1985-2004). Multisite environmental and biological datasets were analysed using multiple CO-inertia analysis (MCOA) and Procrustean analysis. Changes in environmental conditions were mainly marked by an improvement in water quality between 1985 and 1991 and by an increase in water temperature from 1985 onwards due to climate change. Improvement in water quality seemed to delay changes in community structures under global warming. We then observed trends in community structures coupled with high temperatures and a decrease in oxygen content. Interestingly, we observed both gradual changes and rapid switches in community states. These shifts seemed coupled to extreme hydroclimatic events (i.e. pulse disturbances). Floods and the 2003 heatwave enhanced the development of eurytolerant and invasive taxa which were probably able to take advantage of gradual warming environmental conditions. Despite various site-specific "press" constraints (e.g. hydropower schemes, nuclear power plants), similar changes in community structures were observed along the French Rhône River. Such consistency in temporal processes at large geographical scales underlined the strength of hydroclimatic constraints on community dynamics compared to specific local disturbances. Finally, community structures did not show any sign of recovery, and their relative sensitivities to extreme hydroclimatic events seemed to increase with time. Thus, our results suggest that global changes may reduce the resilience of current community states.

Metacommunity studies have demonstrated that local macroinvertebrate communities are structured not only by local environmental conditions but also by spatial processes. Effective bioassessment tools should account for spatial processes while doing so with the least amount of cost. In this study, we applied variance partition techniques based on redundancy analysis to assess the performance of three sets of benthic invertebrate metrics in detecting agricultural land-use effects in a SE Brazil rainforest watershed. Macroinvertebrate data were analyzed separately regarding their taxonomic, functional structure and bioindicator metrics developed for the study region. We stipulated that groups of metrics most sensitive to land-use effects should have the highest amount of variance explained by the joint effects of land use and environmental variation, independently of spatial structuring. Statistical analyses were repeated removing rare taxa in order to assess the effects of their inclusion in the responsiveness of each group of metrics. Traditional bioindicator metrics were more responsive to environmental variation associated with agriculture than taxa abundances and functional attributes. Furthermore, a few common taxa drove a high proportion of the variation observed in invertebrate communities, regardless of how invertebrate data were organized. Similar analytic approaches have the potential to be useful in curtailing sorting and identification efforts when developing macroinvertebrate-based biomonitoring protocols, especially in areas where information regarding the taxonomy of benthic communities is still poorly described. [ABSTRACT FROM AUTHOR]

Simple Summary: This study investigates the evolutionary dynamics of macroinvertebrate functional traits within the Irtysh River Basin under the influence of urbanization. Through comprehensive field assessments and data analysis, we document a significant transition process toward pollution-tolerant functional characteristics in macroinvertebrates, coinciding with the rapid pace of urban development. Simultaneously, the community undergoes a gradual transition, marked by an increase in pollution-tolerant taxa. Urbanization-induced environmental pollution and waste discharge emerge as prominent catalysts, accelerating the observed changes in macroinvertebrate communities and functional traits. Our findings underscore the critical role of anthropogenic factors in aquatic ecosystems and highlight the imperative of strategic management strategies to mitigate these effects. This study contributes to a deeper understanding of the intricate interplay among urbanization, environmental change, and benthic organism responses, providing essential insights for sustainable river management amidst urban expansion. Little is known about how changes in the biodiversity and functional traits of macroinvertebrates in rivers respond to the responses of anthropic pressures and their driving factors. Macroinvertebrates were sampled at 17 sites in the Irtysh River Basin and classified macroinvertebrates into 10 traits and 38 categories between May and August 2022. Then, we performed R-mode linked to Q-mode (RLQ) analysis and calculated functional richness, evenness, divergence, and Rao's quadratic entropy (RaoQ) for each site and community-weighted means for each trait category. Our results indicated that there were pronounced alterations in species variability in the urban region. Functional divergence indicated fierce competition among species and considerable niche overlap in the urban region. Functional evenness indicated that species abundance distribution and interspecific functional distance were not uniform in the urban region. Functional richness indicated that the urban region was the strongest region in terms of niche occupation, resource utilization, and buffering capacity for environmental fluctuations. Rao's quadratic entropy showed that the trait difference of macroinvertebrates was the largest in all regions, which was caused by the gradient environmental difference. Research has revealed that urbanization significantly influences the evolutionary trajectory of macroinvertebrate fauna, culminating in an upsurge in pollution-tolerant species and a convergence of functional traits. We recommend strengthening the control of urban and industrial pollution and wise planning and management of land and water resources to mitigate the impact of anthropogenic destruction on habitat fragmentation in the Irtysh River Basin. [ABSTRACT FROM AUTHOR]

Hydropeaking operation leads to fluctuations in wetted area between base and peak flow and increases discharge‐related hydraulic forces (e.g. flow velocity). These processes promote macroinvertebrate drift and stranding, often affecting benthic abundance and biomass. Our field experimental study—conducted in three hydropeaking‐regulated Swiss rivers—aimed to quantify (a) the short‐term effects of the combined increase in flow amplitude and up‐ramping rate based on macroinvertebrate drift and stranding, as well as (b) long‐term effects based on the established community composition. Hydropeaking led to increased macroinvertebrate drift compared to base flow and to unaffected residual flow reaches. Moreover, stranding of macroinvertebrates was positively related to drift, especially during the up‐ramping phase. Flow velocity and up‐ramping rate were identified as major determinants for macroinvertebrate drift, while flow ratio and down‐ramping rate for stranding. Particularly high sensitivity towards hydropeaking was found for Limnephilidae, whereas Heptageniidae seemed to be resistant in respect to short‐ and long‐term hydropeaking effects. In the long‐term, hydropeaking did not considerably reduce benthic density of most taxa, especially of some highly resistant and resilient taxa such as Chironomidae and Baetidae, which dominated the community composition even though they showed comparably high drift and stranding responses. Therefore, we argue that high drift and/or stranding, especially of individual‐rich taxa, does not necessarily indicate strong hydropeaking sensitivity. Finally, our results demonstrate the necessity to consider the differences in river‐specific morphological complexity and hydropeaking intensity, since these factors strongly influence the community composition and short‐term drift and stranding response of macroinvertebrates to hydropower pressure. [ABSTRACT FROM AUTHOR]

Environmental flows have primarily a practical purpose, being an important part of water management. Despite the widespread use of environmental flows, current studies rarely describe practical insights of the methods or consider environmental flows based on ecological traits, especially regarding macroinvertebrates. In addition to hydraulic parameters, the ecological traits may also indicate processes that drive the distribution of organisms. Nevertheless, so far the habitat suitability criteria for functional feeding groups, the most commonly used ecological trait for macroinvertebrates, have not been described. In this study, we performed a detailed analysis of habitat suitability curves for the macroinvertebrate community and for FFGs. The criteria were determined based on data collected during two field campaigns (2018 and 2019) from the Flinta River, a lowland, dynamic, sandy stream located in western Poland. The method of habitat preference curves (HPCs) for flow velocities, depths and substrate was adopted. Before determining the final habitat suitability criteria, for all considered groups the habitat preference curves and habitat utilization curves were determined separately for the data collected in 2018 and 2019. The results showed that this step was key in developing the final habitat suitability criteria. Additionally, considering FFGs provided insight into the mechanisms that drove the distribution of organisms and resultant suitability. [ABSTRACT FROM AUTHOR]

The transferability of hydraulic microhabitat selection models among rivers has been largely debated. It can influence management decisions such as restoration measures or environmental flow definitions. We updated microhabitat selection models for 258 macroinvertebrate taxa, with 141 species, collected in 2128 Surber or Hess samples during 91 surveys (sites × dates) distributed in eleven small streams to large rivers of Germany and France. We compared microhabitat selection for four hydraulic variables, developed using mixed-effects models that account for the overdispersion of observed abundance, partly due to spatial aggregation. Models based on bed shear stress, water column velocity and Froude number showed comparable results and were stronger than models for water depth. For these velocity-related variables, 61–78% of models were significant and revealed variable response forms among taxa. The explanatory power of "average" microhabitat selection models, with response forms common to all surveys, was 78–83% of the explanatory power of more detailed models with variable response forms. Significant associations with biological traits such as locomotion, relation to substrate or food types suggested that microhabitat selection results from general biological processes. Our results indicate a high degree of transferability and can be useful in many basic and applied ecological studies. [ABSTRACT FROM AUTHOR]

The differences between temperate and tropical seasonality suggest that ecological models developed for temperate streams do not necessarily apply to tropical streams. While detritus is the base of the temperate zone stream food webs, we expected a seasonal alternation in the energy source in tropical streams (i.e., increase in the autochthonous energy source in the dry season, and an increase in the allochthonous energy source in the rainy season). We sought to evaluate the annual dynamics of the benthic macroinvertebrate functional feeding group (FFG) communities, the availability of their food resources, and the use of FFG ratios as surrogates for stream ecosystem traits in two first-order, tropical streams in Chiapas, Mexico. We found an increase in the biomass of herbivore-FFGs correlated to their autochthonous food resources in the dry season. The detritivore-FFGs biomass did not correlate to the abundance of the allochthonous food resources. Stream ecosystem traits were similar between seasons and were associated with a dominance of scrapers, shredders, and predators throughout the year. We concluded that the temperate classical ecological stream models that suggest allochthonous resources almost entirely support food webs do not directly extrapolate to tropical stream ecosystems. Instead, tropical stream food webs significantly rely on autochthonous food resources. [ABSTRACT FROM AUTHOR]

We aimed to quantify the delayed effects of flows on aquatic ecosystems using 33 years of monitoring data on macroinvertebrates and water quality and 51 years of hydrological data, spanning 2,300 km of the Murray River, Australia. By incorporating the delayed effects of hydrological indices, along with physicochemical variables, into generalized additive models to form distributed lag nonlinear models for macroinvertebrate richness and abundance, we found that the effects of floods on macroinvertebrates could last up to 32 years, depending on their magnitude. The models indicated that a large flood can cause an initial depression in macroinvertebrate abundance and richness, followed by a sustained increase persisting for over 25 years before returning to preflood levels. Twelve hydrological indices representing the magnitude of flow events were evaluated, with the q90/med (the 6‐monthly flow exceeded 10% of time, divided by the long‐term median) performing (slightly) better than other indices. Competing hypotheses for the mechanisms underlying the apparent long‐term effect of floods were considered, with the most plausible explanation being the flood‐mediated influx of allochthonous organic matter, especially coarse and large woody debris, that might drive the persistent change in the aquatic community. It is generally believed that macroinvertebrate communities recover quickly after floods, but our findings suggest that we may need to reconceptualize the effects that floods can have on aquatic macroinvertebrates and the communities they support, especially in the context of flow restoration and climate change. Plain Language Summary: Research is being done around the world to understand how much water is required to sustain river ecosystems, and therefore, how much can be extracted for consumptive uses such as irrigated agriculture. We used long‐term monitoring data (1980–2012) on aquatic macroinvertebrates—which includes insects, crustaceans, mussels, snails, and worms that spend all or part of their life in water—collected along 2,300 km of the Murray River, Australia, to investigate the relationship between river flow and the health of aquatic ecosystems. These data indicate that small to medium flows might have an immediate effect through improvements in water quality, but large floods may have sizeable delayed impacts on macroinvertebrates lasting more than three decades. The number of species and overall abundance of macroinvertebrates initially decreased, due to washout, but then increased for a period of about 25 years after the historic flood of 1993, persisting throughout the Millennium drought (1996–2010). The positive legacy of floods might be due to an influx of woody debris during the event, which can provide habitat and food for macroinvertebrates until decomposition of the woody material is complete. Key Points: Long‐term data on macroinvertebrates, water quality, and hydrology in the Murray River enabled quantifying the flow‐ecology relationshipFlood impacts on macroinvertebrate abundance and richness may persist for decades, while small to medium flows have indiscernible effectsA flood‐induced influx of organic matter might underlie the apparent long‐term effect of floods [ABSTRACT FROM AUTHOR]

We investigated the ecological effects of salinity mitigation strategies in the Murray‐Darling Basin (MDB) using macroinvertebrate data collected over 2,300 km of the Murray River between 1980 and 2012. The MDB covers 1 × 106km2 and includes both temperate and semiarid climate zones. It was extensively developed to support irrigated agriculture in the early to mid‐1900s, and the secondary salinization that followed has become a major concern. During 1975–1985 daily salinity levels, measured as electrical conductivity above the Murray River off‐take points for South Australia's major urban water supplies, were above 800 μS/cm for 40% of the time, necessitating mitigation strategies that have reduced the average salinity by about 150 μS/cm since monitoring began. The MDB has also experienced several major floods and droughts during this time, and surface temperatures in the MDB have increased by 0.8 °C since 1910, mostly in the last 50 years. We hypothesized that (1) taxa richness would increase in response to floods; (2) community structure would shift toward tolerant, opportunistic taxa in response to warming; and (3) geographical ranges of species would change in response to shifting stream isotherms and reducing salinity. Our hypotheses were supported, although increases in water temperature appeared to be due principally to the 1997–2009 Millennium drought. Importantly, against a backdrop of significant climate variability, we believe we have distinguished a change in community structure along a salinity gradient and that changes over the 33 years can in part be attributed to mitigation strategies. Plain Language Summary: Groundwater in the Murray‐Darling Basin is naturally salty as a result of the low rainfall and high evaporation that has concentrated salt borne by the rain over tens of thousands of years. The introduction and expansion of irrigated agriculture since the early 1900s rose water tables over large areas and increased the discharge of saline groundwater into the Murray River. The increasing salinity in the lower Murray River raised environmental and public health concerns in the 1970s, and a program of salinity mitigation was implemented. Using long‐term data, we have documented changes occurring along 2,300 km of the Murray River over a 33‐year period. Aquatic macroinvertebrates—which includes insects, crustaceans, mussels, snails, and worms that spend all or part of their life in water—have increased or decreased in abundance in response to natural factors such as floods and droughts and also to changes brought about by the construction of weirs and the side effects of agriculture on the pH and salinity of river water. Importantly, there are ecological signs that salinity mitigation strategies have been effective in reversing past impacts. Key Points: The Murray‐Darling Basin, which covers one million square kilometers, was developed to support irrigated agriculture from the early 1900sThe secondary salinization that followed became a major concern, and mitigation strategies have since reduced salinity levelsEvidence from long‐term monitoring of macroinvertebrates suggests that salinity mitigation has been effective in reversing past impacts [ABSTRACT FROM AUTHOR]

Abstract: Understanding the physical and biological mechanisms contributing to flow velocity–ecology relationships is crucial for successful river management. The application of an ecological traits‐based approach offers the potential to explore mechanistic linkages between aquatic communities and a hydrological gradient. To date, however, studies focused on identifying these relationships have been limited by a lack of large‐scale, long‐term biological data. To address this gap at a scale relevant for water policy management, we employed data from a large‐scale standardised benthic monitoring program—the Canadian Aquatic Biomonitoring Network—obtained from wadeable river sites across Canada. We applied the Threshold Indicator Taxa ANalysis method to quantify the response of the macroinvertebrate community, expressed as traditional taxonomic information and also as ecological traits, along a flow velocity gradient in reference and potential reference sites. Five key findings emerged: (1) using taxa and trait modalities revealed different flow velocity thresholds, (2) trait flow velocity indicators were less variable than taxon indicators, especially for positively responding trait modalities, (3) labile and non‐labile trait modalities demonstrated highly similar patterns along the flow velocity gradient, (4) taxa from 12 different orders responded negatively to flow velocity, while only EPT taxa and some dipterans responded positively to flow velocity, and (5) traits related to mobility and ecology (e.g. climber and swimmer habits, preference of cold‐cool eurythermal water and ability to survive desiccation) tended to respond positively to flow velocity, while traits related to morphology, life history and ecology (e.g. sprawler and burrower habits, preference for warm eurythermal water and inability to survive desiccation) tended to respond negatively to flow velocity. Providing ecologically based flow management targets can improve management plans, anticipate ecosystem consequences of anthropogenic change and support the development of policies to mitigate anthropogenic flow alteration. While our taxon and trait modality flow indicators were developed for Canadian watersheds, our methods to develop flow indicators and thresholds are transferrable to other systems where long‐term biomonitoring programs are being developed, underscoring the need for long‐term biomonitoring programs to support better ecosystem management. [ABSTRACT FROM AUTHOR]

Riverbank erosion is linked to increasing risks in piedmont areas due to urbanization and hydromorphological alterations of rivers. Changes in riparian vegetation and in sediment dynamics modify aquatic macroinvertebrate communities. In this context, riverbank stabilization is a major issue in the conservation of stream ecosystem functioning. In this study, we aimed at assessing the impacts of riverbank stabilization techniques on the taxonomic and functional properties of benthic macroinvertebrate communities living in alpine mountain streams. For this purpose, the effects of four riverbank stabilization techniques (riprap, mixed, cribwall, and fascine) on the taxonomic richness and biological traits involved in the main ecological processes were tested and compared with natural bank conditions. Overall, the macroinvertebrate richness was lower in stabilized banks than in natural conditions, and communities welcomed on natural banks were significantly different from those found on managed banks. The biological trait composition such as 'maximum potential size,' 'life cycle duration,' 'reproduction,' 'feeding habits,' and 'trophic status' differed significantly among riverbanks, especially between natural banks and the riprap, mixed, and cribwall trio. In a context of macroinvertebrate biodiversity and functional restoration, we can advocate the fascine technique as the most suitable technique tested. [ABSTRACT FROM AUTHOR]

The widespread degradation of lotic ecosystems has prompted extensive river restoration efforts globally, but many studies have reported modest ecological responses to rehabilitation practices. The functional properties of biotic communities are rarely examined within post-project appraisals, which would provide more ecological information underpinning ecosystem responses to restoration practices and potentially pinpoint project limitations. This study examines macroinvertebrate community responses to three projects which aimed to physically restore channel morphologies. Taxonomic and functional trait compositions supported by widely occurring lotic habitats (biotopes) were examined across paired restored and non-restored (control) reaches. The multivariate location (average community composition) of taxonomic and functional trait compositions differed marginally between control and restored reaches. However, changes in the amount of multivariate dispersion were more robust and indicated greater ecological heterogeneity within restored reaches, particularly when considering functional trait compositions. Organic biotopes (macrophyte stands and macroalgae) occurred widely across all study sites and supported a high alpha (within-habitat) taxonomic diversity compared to mineralogical biotopes (sand and gravel patches), which were characteristic of restored reaches. However, mineralogical biotopes possessed a higher beta (between-habitat) functional diversity, although this was less pronounced for taxonomic compositions. This study demonstrates that examining the functional and structural properties of taxa across distinct biotopes can provide a greater understanding of biotic responses to river restoration works. Such information could be used to better understand the ecological implications of rehabilitation practices and guide more effective management strategies. [ABSTRACT FROM AUTHOR]

Although species traits have the potential to disentangle long-term effects of multiple, potentially confounded drivers in ecosystems, this issue has received very little attention in the literature. We aimed at filling this gap by assessing the relative effects of hydroclimatic and water quality factors on the trait composition of invertebrate assemblages over 30 years in the Middle Loire River (France). Using a priori predictions on the long-term variation of trait-based adaptations over the three decades, we evaluated the ability of invertebrate traits to indicate the effects of warming, discharge reduction and water quality improvement. Hydroclimatic and water quality factors contributed to up to 65% of the variation in trait composition. More than 70% of the initial trait response predictions made according to observed long-term hydroclimatic changes were confirmed. They supported a general climate-induced trend involving adapted resistance and resilience strategies. A partial confounding effect of water quality improvement acting on trophic processes was also highlighted, indicating that improved water quality management can significantly help to reduce some adverse effects of climate change. This trait-based approach can have wider implications for investigating long-term changes driven by multiple, potentially confounded factors, as frequently encountered in the context of global change. [ABSTRACT FROM AUTHOR]

Although several studies have examined the functional diversity of freshwater macroinvertebrates, the variety of methodologies combined with the absence of a synthetic review make our understanding of this field incomplete. Therefore, we reviewed the current methodology for assessing functional diversity in freshwater macroinvertebrate research. Our review showed that most papers quantified functional diversity using biological traits, among which feeding habits were the most common traits probably due to the assumed links between feeding and ecosystem functions. A large number of diversity measures have been applied for quantifying functional diversity of freshwater macroinvertebrate assemblages, among which Rao's quadratic entropy looks like the most frequent. In most papers, functional diversity was positively related to taxon richness, and functional redundancy was a key concept in explaining this correlation. Most studies detected strong influence of the environmental factors as well as human impact on functional diversity. Finally, our review revealed that functional diversity research is biased towards European running waters and is hindered by yet insufficient information on the autecology of macroinvertebrates. [ABSTRACT FROM AUTHOR]

Several studies on global change over the next century predict increases in mean air temperatures of between 1°C to 5°C that would affect not only water temperature but also river flow. Climate is the predominant environmental driver of thermal and flow regimes of freshwater ecosystems, determining survival, growth, metabolism, phenology and behaviour as well as biotic interactions of aquatic fauna. Thus, these changes would also have consequences for species phenology, their distribution range, and the composition and dynamics of communities. These effects are expected to be especially severe in the Mediterranean basin due its particular climate conditions, seriously threatening Southern European ecosystems. In addition, species with restricted distributions and narrow ecological requirements, such as those living in the headwaters of rivers, will be severely affected. The study area corresponds to the Spanish Mediterranean and Balearic Islands, delimited by the Köppen climate boundary. With the application of the MEDPACS (MEDiterranean Prediction And Classification System) predictive approach, the macroinvertebrate community was predicted for current conditions and compared with three posible scenarios of watertemperature increase and its associated water flow reductions. The results indicate that the aquatic macroinvertebrate communities will undergo a drastic impact, with reductions in taxa richness for each scenario in relation to simulated current conditions, accompanied by changes in the taxa distribution pattern. Accordingly, the distribution area of most of the taxa (65.96%) inhabiting the mid-high elevations would contract and rise in altitude. Thus, families containing a great number of generalist species will move upstream to colonize new zones with lower water temperatures. By contrast, more vulnerable taxa will undergo reductions in their distribution area. [ABSTRACT FROM AUTHOR]

1. In stream ecology, it has traditionally been proposed that local habitat conditions pose a strong environmental filter resulting in predictable community types. However, recent studies have demonstrated continuous rather than discrete community variation along environmental gradients across streams. 2. Our aim was to examine the continuity of stream communities using functional traits of benthic macroinvertebrates. Using previous studies and the environmental filtering paradigm as a background, we hypothesised that the taxonomic composition of communities should vary continuously over environmental gradients, whereas the functional composition of communities should form discrete community types according to specific habitat conditions. As stream environmental characteristics vary between seasons, we also asked if this had an effect on the characteristics of community variation in time. 3. Our data were collected from 50 streams draining into the River Tenojoki (70N, 27E) in Finland and Norway. The first data set was collected during late spring 2013 and the second data set during early autumn of the same year. Using multivariate regression trees and constrained ordination methods, we analysed the relationships of taxonomic and functional composition of macroinvertebrate communities to various in-stream environmental factors. 4. Our results suggest that the variation in the importance of environmental factors between seasons combined with the high heterogeneity of habitats precludes the formation of clear taxonomic and functional community types in northern streams. 5. Conservation efforts should hence focus on including variability in environmental conditions so as to encompass all components of biological communities. However, as there were some noticeable responses of individual traits to different environmental factors, discrete functional communities may be found if key traits of the organisms can be identified. [ABSTRACT FROM AUTHOR]

Flow regulation via impoundments threatens lotic ecosystems and the services they provide globally. Impoundments drastically alter flow and stream temperature variability within fluvial environments, but efforts to quantify ecohydrological and ecothermal responses to flow regulation in conjunction have been sparsely explored to date. This study examined macroinvertebrate community responses to antecedent flow (discharge) and stream temperature variability across paired regulated and non-regulated systems associated with three reservoirs located in adjacent catchments. Community abundances, functional traits, and biomonitoring indices were examined, and ecological differences between non-regulated and regulated sites were quantified, with the most sensitive faunal response being correlated against a suite of flow and thermal indices. Regulated sites exhibited reduced low-flow variability and rapid increases in discharge during peak flows that regularly exceeded those conveyed by non-regulated sites, while stream temperature variability was highly congruent between sites. Macroinvertebrate functional traits were particularly sensitive to flow regulation, and incorporating biomonitoring indices marginally improved the ecological discrimination between regulated and non-regulated sites. Unlike community abundances, functional traits did not vary spatially between catchments, highlighting that such information could guide the implementation of regional environmental flows. Macroinvertebrate communities responded significantly to various hydrological parameters, particularly those associated with the timing of extreme flows, but were less sensitive to thermal controls. Future research should explore ecological responses to antecedent hydrological and stream temperature variability associated with flow regulation to provide a better understanding of the underlying mechanisms driving biotic alterations, which could guide future environmental flow methodologies. [ABSTRACT FROM AUTHOR]

Massive tsunamis induce catastrophic disturbance in marine ecosystems, yet they can provide unique opportunities to observe the process of regeneration. Here, we report the recovery of fauna after the 2011 tsunami in northeast Japan based on underwater visual censuses performed every two months over five years. Both total fish abundance and species richness increased from the first to the second year after the tsunami followed by stabilization in the following years. Short-lived fish, such as the banded goby Pterogobius elapoides, were relatively abundant in the first two years, whereas long-lived species, such as the black rockfish Sebastes cheni, increased in the latter half of the survey period. Tropical fish species were recorded only in the second and third years after the tsunami. The body size of long-lived fish increased during the survey period resulting in a gradual increase of total fish biomass. The recovery of fish assemblages was slow at one site located in the inner bay, where the impact of the tsunami was the strongest. Apart from fish, blooms of the moon jellyfish Aurelia sp. occurred only in the first two years after the tsunami, whereas the abundances of sea cucumber Apostichopus japonicus and abalone Haliotis discus hannai increased after the second year. Although we lack quantitative data prior to the tsunami, we conclude that it takes approximately three years for coastal reef fish assemblages to recover from a heavy disturbance such as a tsunami and that the recovery is dependent on species-specific life span and habitat. [ABSTRACT FROM AUTHOR]

Anthropogenic disturbances affect ecosystem structure and functioning. The quantification of their impacts on highly diverse and structurally complex ecosystems, such as coral reefs, is challenging. These communities are facing rising fishing pressure, particularly on Pacific Islands such as New Caledonia. The main objective was to quantify harvesting effects on invertebrate assemblages across two contrasting habitats (soft- and hard-bottom), by comparing communities in marine protected areas (MPAs) with non-MPAs using 10 biological and ecological traits. Patterns of trait composition were compared with those of species composition by non-metric multidimensional scaling and permutational analysis of variance analyses. Traits most responsible for differences between MPAs and non-MPAs were determined using SIMPER analysis, and predictions on shellfishing effects were discussed. A total of 248 species were recorded in hard-bottom communities, mainly characterized by mobile epifauna living on corals, crawling, and possessing a shell (molluscs) or a cuticle (crabs and echinoderms). Soft-bottom habitats contained 166 species, dominated by burrowing and sedentary species, especially shelled (largely bivalves) and worm-like organisms. Clear differences in species and trait composition between MPA and non-MPAs were highlighted in both habitats. Harvesting activities have community-wide effects that change the functional composition of invertebrate assemblages, in particular in terms of living habits and mobility. The observed shifts in benthic communities can affect the functioning of tropical coastal ecosystems and need to be included in small-scale fisheries management in poorly known tropical environments. [ABSTRACT FROM AUTHOR]

While taxonomic metrics are common indicators for assessing impact of acid mine drainage (AMD) on macroinvertebrates, functional diversity metrics are scarcely used. We tested the hypothesis that functional diversity metrics could be used as indicators for assessing impact of AMD on macroinvertebrates. Differences in both taxonomic metrics and functional diversity metrics were examined among sites with varying levels of AMD impact. AMD led to loss of sensitive functional groups and resulted in low functional diversity in the impacted sites. Functional richness, functional Shannon's index and functional Brillouin's index were significantly correlated with all key AMD parameters. Compared to taxonomic metrics, functional diversity metrics had higher correlations with most key AMD parameters. Functional diversity metrics were more informative than taxonomic metrics for assessing impact of AMD on macroinvertebrates since they were more effective at indicating mild or moderate AMD pollution. Functional Shannon's index and functional Brillouin's index were the most precise metrics. [ABSTRACT FROM PUBLISHER]

Higher-tier ecological risk assessment of chemicals often relies upon studies in dynamic and/or static mesocosms. Physico-chemical and hydrological properties of each type of mesocosm result in specific chemicals fate, community functioning, and potential recovery. In the present study, macroinvertebrate abundance- and biomass-weighted biological and ecological trait matrices were used to assess the effects of a dithiocarbamate fungicide, thiram (35 and 170 µg l), and of a petroleum middle distillate (0.01, 0.4, 2 and 20 mg l) in outdoor stream and pond mesocosms. Trait sensitivity was characterized using functional diversity indices and trait modality distributions to assess the influence of the type of experimental systems and the ability of traits to disentangle chemical-induced effects from temporal and stochastic variations. In addition, leaf litter breakdown was used as an integrative functional endpoint. Regardless to the substance, treatments had a direct effect on the functional structure of benthic macroinvertebrate communities in streams but not in ponds, suggesting that global functional responses to chemicals are system-specific. Although both substances had an effect in streams, differences were noticed in the nature of the affected traits suggesting that chemical mode of action plays a role in functional alterations. This was illustrated by the link between negative effects of chemical exposure on detritivorous taxa and reduced litter breakdown rate in streams. Therefore, characterisation of macroinvertebrate biological traits associated with the measurement of a functional process such as litter breakdown may provide a comprehensive understanding of the effects occurring in mesocosms exposed to organic chemicals. [ABSTRACT FROM AUTHOR]

Traits-based community analyses are receiving increasing attention. However, consistent interpretation of empirical results and ecological understanding in stream ecology are limited by ambiguous terminology. Furthermore, the measurement scales used to analyze trait data, especially ordinal-scale data, are often inappropriately applied. We identify and discuss these shortcomings and offer a solution for an operative and algebraically correct treatment of traits and a unified nomenclature that facilitates direct comparison among traits-based studies. A unified terminology allows for logical translation among existing, alternative trait nomenclatures and should facilitate communication of research findings among stream ecologists and more directly connect stream traits-based research with general ecology. [ABSTRACT FROM AUTHOR]

Lotic environments contain a disproportionate amount of biodiversity given their relatively small proportion of the worldwide landscape. We conducted a systematic literature search of research directed towards understanding factors that influence biodiversity in lotic habitats, published in 31 major ecological and freshwater science journals from 1981 to 2014. Our goal was to characterize emergent themes in research successes and identify important areas in need of study. We show an overwhelming taxonomic bias favoring studies of macroinvertebrates and fish, and a paucity in studies of other important groups such as bacteria and fungi. While most studies assessed habitat variables that affect diversity at a local scale, there has been a recent push to investigate regional drivers of beta and gamma diversity. Several factors were consistently found to be important drivers of diversity including local habitat type, hydrologic variables, disturbance, and stream morphometry. Others such as nutrients and chemical variables showed mixed support. Species interactions, dispersal, and evolutionary processes were rarely considered but show promise as fruitful areas for future study. We suggest that researchers should give increased attention to diversity drivers at different scales as well as take advantage of new molecular techniques to address questions regarding organismal diversity in streams. [ABSTRACT FROM AUTHOR]

Numerous wetland restoration projects have been implemented in recent years to mitigate the increasing loss of global wetland surface area caused by human activities. Most of these projects have focused on the local recovery of habitats and species diversity, with little evaluation of functional recovery. We aimed at demonstrating that constructing wetlands on a degraded floodplain increases not only the taxonomic, but also the functional diversity of macroinvertebrate assemblages by providing greater water quality to the local fauna. We studied the macroinvertebrate community using taxonomic and functional diversity indices, and the physicochemical characteristics of three wetlands constructed 5-25 years ago, and three relict natural wetlands on the floodplain of a regulated river (Ebro River, NE Spain). Constructed wetlands demonstrated significantly greater taxonomic abundance and richness of macroinvertebrates than natural wetlands. At the functional level, the richness and Shannon diversity of biological traits relating to reproduction, respiration, dispersal and feeding were also greater in constructed wetlands, which is partly explained by low inorganic nitrogen concentration in these habitats. In contrast, a high content of phosphorus and water organic matter led to the lowest values of taxonomic and functional diversity found in natural wetlands. We conclude that it is essential to consider not only taxonomic but also functional aspects at all stages of a restoration project in order to optimize its long-term efficacy to provide and support key species and functions. [ABSTRACT FROM AUTHOR]

Bioassessment tools should distinguish between the effects of anthropogenic degradation in communities and natural temporal changes. The present study tests the influence of natural seasonal variability on macroinvertebrate stream communities assessed by a predictive model (PORTRIV) and a multimetric index (IPtI) calibrated for spring. The scores of PORTRIV decreased significantly between spring and autumn, and between spring and winter (ca. 37 to 53 %, respectively), while those of IPtI did not change significantly between seasons. For non-reference samples, the results of the predictive model also indicate no significant differences. A correction factor (CF) was calculated to adjust the existing differences in the model assessments between seasons, based on the percentage of variation of reference site scores from spring to autumn and winter. After the application of the CF to the OE50 scores of spring reference samples, the differences were no longer significant. Independent reference validation sites confirmed this tendency. This method has the advantage of avoiding large efforts required for the construction of databases from other seasons and the development of new models to allow the assessment of streams in seasons other than spring. Further tests with models developed in regions with more marked seasonal changes should be done to confirm its wider applicability. [ABSTRACT FROM AUTHOR]

Elevated levels of fine sediment (suspended and deposited) are a common cause of ecological degradation in freshwater ecosystems. However, it is time-consuming and expensive to monitor these parameters to support national and international water resource legislation., The Proportion of Sediment-sensitive Invertebrates ( PSI) index is a biomonitoring tool that is designed to identify the degree of sedimentation in rivers and streams. Despite having a sound biological basis, until now, the PSI index has only been tested against observed fine sediment data in two catchments; other published applications of the PSI index have relied on inferred fine sediment values., In this study, we report the results of a comprehensive analysis of the performance of the PSI index across a wide range of reference condition temperate stream and river ecosystems, including 835 sites with data on deposited sediment and 451 sites with data on suspended solids (>12 500 data points measured between 1978 and 2002)., The effect of taxonomic level and taxonomic resolution on the performance of the PSI index was also examined, as was the performance of the PSI index against other non-sediment-specific indices, including Average Score Per Taxon ( ASPT), Lotic-invertebrate Index for Flow Evaluation ( LIFE), Ephemeroptera, Plecoptera and Trichoptera ( EPT) abundance, % EPT abundance, EPT richness and % EPT richness., The results of this study show that the PSI index was more correlated with fine sediment metrics than the other biological indices tested: rs = −0.64, ( P < 0.01, n = 2502) for deposited sediment and rs = −0.50 ( P < 0.01, n = 1353) for suspended solids., We highlight the optimal conditions for applying the PSI index, in its current form. Given the variability in the relationship between PSI and fine sediment metrics, we propose that the use of data from more objective, quantitative methods of measuring deposited fine sediment may help to enhance the performance of the model for future applications and advance understanding of fine sediment dynamics and the pressure-response relationship. [ABSTRACT FROM AUTHOR]

Aim Invertebrates are often overlooked in assessments of climate change impacts. Odonata (dragonflies and damselflies) are a significant component of freshwater macroinvertebrate diversity and are likely to be highly responsive to a changing climate. We investigate whether climate change could lead to significant alteration of continental patterns of diversity and whether vulnerable species are taxonomically clustered. Location Australia. Methods Habitat suitability of 270 odonate species was modelled, and a simplified phylogeny was developed based on taxonomic relationships and expert opinion. These maps were then combined to compare species richness, endemism, taxonomic diversity ( TD) and taxonomic endemism ( TE) under climate change scenarios, and estimate turnover in species composition. Based on the concentration of vulnerable species in regions associated with Gondwanan relicts, we tested the possibility that a focus on species loss would underestimate loss of evolutionary diversity. Results Species richness of Australian Odonata is concentrated in the Wet Tropics, central-north Australia and south-east Queensland. Several additional regions support endemic assemblages, including the Victorian alpine region, the Pilbara and far south-western Australia. Major shifts in composition are expected across most of the east coast in response to climate change, and Tasmania has the potential to become a major refuge for mainland species. For many regions, the loss of TD is greater than expected based on the changes in species richness, and the loss of suitable habitat was unevenly distributed among families. However, the potential loss of evolutionary diversity among vulnerable species was not significantly different from random. Main conclusions The major shifts in the distribution of Australian odonate diversity predicted to occur under climate change imply major challenges for conservation of freshwater biodiversity overall. Although major evolutionary losses may be avoided, climate change is still a serious threat to Australia's Odonata and poses an even greater threat to Australian freshwater biodiversity as a whole. [ABSTRACT FROM AUTHOR]

Heino et al. () identified the weak explanatory power of abundance data as an important limitation of macroinvertebrate trait analysis. This limitation may be an artefact of analytical design., The widespread practice of combining logarithmically transformed abundance data with trait frequencies, log(x + 1)*(trait frequency), represents a nonlinear abundance weighting of trait frequencies, as opposed to an expression of trait abundances per se. Because the addition of logarithmic data is equivalent to multiplication on an arithmetic scale, summing these abundance-weighted frequencies provides an inconsistent scaling of trait abundance that may confound quantitative comparison., We provide examples of the options for estimating trait abundance from data on macroinvertebrate abundance and trait frequencies and discuss the meaning of numerical data in the context of analytical objectives., In the light of the contrasting methods that have been employed to analyse trait data for benthic macroinvertebrates, the conclusion that the explanatory power of trait abundance is inferior to that of taxonomic abundance may be premature. [ABSTRACT FROM AUTHOR]

Monaghan and Soares (2014) suggested that combining traits with log-transformed abundance of taxa may cause anomalies in analyses of stream macroinvertebrate communities. While they addressed an important issue in stream ecology, here we present an opposite view. To identify the causes of these contrasting opinions, we carefully examined the examples provided by Monaghan and Soares (2014) and demonstrated how traits can be weighted by the presence, abundance and log-transformed abundance of the taxa in a meaningful way., We found that Monaghan and Soares (2014), following other authors, use the term 'weighting' differently from classical papers of stream ecology. The general practice is to calculate the sum of trait values multiplied by the abundance of each taxon and divide it by the total invertebrate abundance to get a community-level trait value. In contrast, Monaghan and Soares (2014) did not perform the final division and consequently did not get a standardised community-level trait value. It follows that the term 'weighting' is used with different meanings in stream ecology, and ecologists should keep these differences in mind., We agree with Monaghan and Soares (2014) that the addition of log-transformed data is equivalent to multiplication on an arithmetic scale. However, we disagree that this provides an inconsistent scaling that confounds quantitative analyses. Using example data sets, we illustrate how trait-based data analysis can be performed in community ecology in a meaningful way. [ABSTRACT FROM AUTHOR]

ABSTRACT In floodplain ecosystems, the lateral hydrological connectivity between the main river channel and the secondary channels plays a major role in shaping both the habitat conditions and the macroinvertebrate diversity. Among other threats, human activities tend to reduce the lateral connectivity, which increases floodplain terrestrialization and induces a loss of aquatic biodiversity. Consequently, the restoration of lateral connectivity is of growing concern. We studied four secondary channels of the Rhône floodplain that were subjected either to no restoration or to three different restoration measures (river flow increase only, flow increase plus dredging and flow increase plus reconnection to the river). Macroinvertebrate and environmental data were analysed one year before and during a period of five years after restoration. We expected a progressive increase of lateral connectivity according to the type of restoration. Changes in macroinvertebrate assemblages were predicted to be towards more rheophilic communities and proportionally related to the changes in lateral connectivity. In the reconnected channel, lateral connectivity increased and remained high five years after restoration. In the dredged channel, the immediate increase of the lateral connectivity metric induced by sediment removal was followed by a rapid decrease. In the unrestored channel and the channel only influenced by flow increase, the metric remained constant in time. The macroinvertebrate composition and the rarefied EPT richness changes were proportionally related to the changes in lateral connectivity. Alien species richness and densities increased progressively in all channels after restoration. Our results showed that modifications of the lateral connectivity lead to predictable changes in macroinvertebrate diversity. Synergistic interactions between restoration and longer-term changes (e.g. climatic change, invasion of alien species) encourage long-term monitoring to assess the durability and trends of restoration measures. Copyright © 2012 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Despite a general recognition that benthic macroinvertebrates respond to changes in hydrological connectivity within floodplain ecosystems, no consensus about patterns in community structure and ecosystem processes across large scales and different climates has yet been established. Such knowledge is necessary since anthropogenic activities continue to alter the natural hydrogeomorphology of large floodplains, with most consequences for aquatic communities remaining unknown., Using information from six large rivers located in four different climate regions (humid subtropical, maritime temperate, Mediterranean and dry semi-arid), we compared benthic macroinvertebrate responses along lateral gradients of hydrological connectivity. We tested hypotheses related to differences among climate regions and to similar hydrological constraints within any one climate. The large geographical scale covered by this study provides the first comprehensive comparison of aquatic community patterns across hydrological gradients under different climatic settings., Multivariate ordinations demonstrated a higher overlap of trait community composition (50% variance explained by the first two axes) than taxonomic composition (15%) among floodplains, displaying high interclimate trait stability. The taxonomy-based ordination separated the subtropical floodplain, with an average 86% of non-insect taxa, from the insect-dominated temperate, Mediterranean and semi-arid floodplains (with >50% insect abundance). In the trait-based ordination, large body size (60% of organisms >4 cm) and long lifespan duration (80% of organisms) discriminated the subtropical from the other five studied floodplains., Across a gradient of lateral connectivity, linear mixed effect ( LME) models supported seven of 15 hypotheses, which suggests remarkably consistent macroinvertebrate patterns in floodplains regardless of the climate regime. Taxon and trait richness were positively related and peaked at sites of intermediate hydrological connectivity. Our predictions about the feeding guilds of macroinvertebrates (e.g. that shredders and scrapers would be more abundant in connected channels, and predators and deposit feeders at isolated sites) were more strongly supported by the data than those about life history (e.g. plurivoltinism and short lifespan would be better represented in connected channels). This difference was related to the influence of extended periods of hydrological disconnection as disturbance in addition to flooding., Trait stability across hydrological connectivity provides a meaningful ecological context for the comparison of the macroinvertebrate benthos among climatic zones, where taxonomic composition differs strongly. In addition, trait similarities and dissimilarities found in this study suggest that large-scale biogeographical filters do operate on communities, resulting in different trait combinations in temperate and Mediterranean floodplains when compared to semi-arid and subtropical environments. The extent to which global macroecological factors (i.e. climate, dispersal history) and local biotic and abiotic factors (i.e. drought frequency, habitat structure, water chemistry) contribute to this difference requires further investigation. [ABSTRACT FROM AUTHOR]

Other than some classical ideas, large-scale approaches to understand variation in organismal traits (or the trait composition of an ecological community) across stream ecosystems are rather recent. Recent case studies and review papers show clear evidence for the usefulness of trait-based analyses in bioassessment, but how community traits vary along natural gradients at large scales has not yet been synthesised. Here, we attempt to fill this gap by providing a synthesis of trait patterns of stream communities from a macroecological perspective., We argue that although both natural and anthropogenic filters shape community traits, examination of poorly understood natural filters, including those acting at large scales, should receive increasing attention. Such knowledge is vital for reliably inferring anthropogenic impacts on stream communities and ecosystems., We synthesise knowledge of two large-scale spatial patterns of stream communities: among drainage basins (i.e. geographical variation) and within drainage basins (i.e. longitudinal variation). We also examine the temporal dimension of organismal traits. Our review highlights clear evidence for large-scale influences on the trait composition in stream systems. For example, despite previous contentions that organismal traits should vary negligibly across large geographical gradients, there is actually clear geographical variation across near-pristine systems. Furthermore, in accordance with theory, organismal traits in actual data sets vary along the longitudinal gradient of stream systems., We provide an overview of empirical and statistical approaches to understanding the trait composition of stream communities in macroecological studies and conclude that the methodology should be carefully considered in comparisons among studies, because contrasting results may reflect not only ecological differences but also differences in methodology (e.g. choice of species traits, trait quantification and analytical methods)., We conclude that the question of how the trait composition of stream communities varies along geographical and environmental gradients is far from settled. A challenge for large-scale stream ecology is to provide a more specific view of trait variation in multiple taxonomic groups (e.g. do traits vary similarly in different organisms groups?), along major environmental gradients (e.g. is trait variation similar along the same environmental gradients in different regions?) and among different regional entities (e.g. do the traits vary, on average, among different regions?). [ABSTRACT FROM AUTHOR]

The unique information provided by multiyear data sets can aid in detecting major long-term trends and making predictions with respect to environmental and biological variables. These trends are expected to differ among climatic regions but little information exists concerning long-term variability within a particular climate region., We analysed the long-term (14-year time span) patterns in species richness and composition of aquatic insects ( EPT: Ephemeroptera, Plecoptera and Trichoptera) in relation to changes in temperature, precipitation and discharge in two reference streams in Catalonia (north-east Spain). Our study sites were located in the Mediterranean macroclimate region but in different mesoclimatic areas, one in the Wet Mediterranean climate area and the other in the Dry Mediterranean climate area ( WM and DM, respectively)., At the macroclimate scale, precipitation decreased and the frequency of drought events increased during the 14-year period. Although the mean number of taxa in each of the two sites remained similar, there was a replacement of species characteristic of riffle-like conditions by species characteristic of pool-like conditions over time in both sites., EPT composition differed between sites at the mesoclimate scale, demonstrating the importance of regional factors. In particular, changes in EPT composition were less variable in WM than in DM both in the short term and in the long term, indicating that the WM site was less constrained by climate than the DM site. Such differences between mesoclimates are related to differences in flood magnitude (higher in WM) and drought frequency (more frequent in DM) as well as local hydromorphological differences., Our findings indicate that the streams responded similarly to long-term patterns in large-scale variables (i.e. those affecting the overall macroclimatic region), but differed with respect to the effect of local-scale variables (i.e. those differentially affecting each mesoclimatic area). Predictive bio-assessment models that use reference conditions must incorporate long-term variability to accurately assess the ecological status of Mediterranean climate streams. [ABSTRACT FROM AUTHOR]

ABSTRACT The sustainability of ecosystem services depends on a firm understanding of both how organisms provide these services to humans and how these organisms will be altered with a changing climate. Unquestionably a dominant feature of most ecosystems, invertebrates affect many ecosystem services and are also highly responsive to climate change. However, there is still a basic lack of understanding of the direct and indirect paths by which invertebrates influence ecosystem services, as well as how climate change will affect those ecosystem services by altering invertebrate populations. This indicates a lack of communication and collaboration among scientists researching ecosystem services and climate change effects on invertebrates, and land managers and researchers from other disciplines, which becomes obvious when systematically reviewing the literature relevant to invertebrates, ecosystem services, and climate change. To address this issue, we review how invertebrates respond to climate change. We then review how invertebrates both positively and negatively influence ecosystem services. Lastly, we provide some critical future directions for research needs, and suggest ways in which managers, scientists and other researchers may collaborate to tackle the complex issue of sustaining invertebrate-mediated services under a changing climate. [ABSTRACT FROM AUTHOR]

Aquatic species living in running waters are widely acknowledged to be vulnerable to climate-induced, thermal and hydrological fluctuations. Climate changes can interact with other environmental changes to determine structural and functional attributes of communities. Although such complex interactions are most likely to occur in a multiple-stressor context as frequently encountered in large rivers, they have received little attention in such ecosystems. In this study, we aimed at specifically addressing the issue of relative long-term effects of global and local changes on benthic macroinvertebrate communities in multistressed large rivers. We assessed effects of hydroclimatic vs. water quality factors on invertebrate community structure and composition over 30 years (1979-2008) in the Middle Loire River, France. As observed in other large European rivers, water warming over the three decades (+0.9 °C between 1979-1988 and 1999-2008) and to a lesser extent discharge reduction (−80 m3 s−1) were significantly involved in the disappearance or decrease in taxa typical from fast running, cold waters (e.g. Chloroperlidae and Potamanthidae). They explained also a major part of the appearance and increase of taxa typical from slow flowing or standing waters and warmer temperatures, including invasive species (e.g. Corbicula sp. and Atyaephyra desmarestii). However, this shift towards a generalist and pollution tolerant assemblage was partially confounded by local improvement in water quality (i.e. phosphate input reduction by about two thirds and eutrophication limitation by almost one half), explaining a significant part of the settlement of new pollution-sensitive taxa (e.g. the caddisfly Brachycentridae and Philopotamidae families) during the last years of the study period. The regain in such taxa allowed maintaining a certain level of specialization in the invertebrate community despite climate change effects. [ABSTRACT FROM AUTHOR]

Climate change is predicted to have profound effects on freshwater organisms due to rising temperatures and altered precipitation regimes. Using an ensemble of bioclimatic envelope models ( BEMs), we modelled the climatic suitability of 191 stream macroinvertebrate species from 12 orders across Europe under two climate change scenarios for 2080 on a spatial resolution of 5 arc minutes. Analyses included assessments of relative changes in species' climatically suitable areas as well as their potential shifts in latitude and longitude with respect to species' thermal preferences. Climate-change effects were also analysed regarding species' ecological and biological groupings, namely (1) endemicity and (2) rarity within European ecoregions, (3) life cycle, (4) stream zonation preference and (5) current preference. The BEMs projected that suitable climate conditions would persist in Europe in the year 2080 for nearly 99% of the modelled species regardless of the climate scenario. Nevertheless, a decrease in the amount of climatically suitable areas was projected for 57-59% of the species. Depending on the scenario, losses could be of 38-44% on average. The suitable areas for species were projected to shift, on average, 4.7-6.6° north and 3.9-5.4° east. Cold-adapted species were projected to lose climatically suitable areas, while gains were expected for warm-adapted species. When projections were analysed for different species groupings, only endemics stood out as a particular group. That is, endemics were projected to lose significantly larger amounts of suitable climatic areas than nonendemic species. Despite the uncertainties involved in modelling exercises such as this, the extent of projected distributional changes reveals further the vulnerability of freshwater organisms to climate change and implies a need to understand the consequences for ecological function and biodiversity conservation. [ABSTRACT FROM AUTHOR]

Rivers and floodplains are among the most threatened ecosystems. Hydroelectric power plants and embankments have reduced the hydrological connectivity between rivers and their floodplain channels, leading to loss of freshwater habitats and biological communities. To prevent and reverse such loss, numerous restoration programmes have aimed at rejuvenating the lateral hydrological connectivity between rivers and floodplain channels. Despite considerable global attention, we know remarkably little about the ecological benefits of floodplain restoration programmes., We analysed the functional diversity of different macroinvertebrate groups (natives and aliens) along a gradient of lateral hydrological connectivity on the Rhône river in France. We used 36 sampling sites to describe the functional diversity (Rao's quadratic entropy) before and after the enhancement of the lateral hydrological connectivity by restoration. The effects of restoration on functional diversity were tested for each macroinvertebrate group and at multiple spatial levels (alpha and beta)., Before restoration, alpha functional diversity of the entire macroinvertebrate community peaked in sites with a high lateral connectivity. The contribution of the native groups to functional diversity was higher than that of the alien group. The latter was not constrained by high values of lateral hydrological connectivity and reached a maximum in highly connected sites., After restoration, within-site functional diversity (alpha FD) declined linearly following the enhancement of lateral hydrological connectivity. The restoration operations increased the contribution of the aliens to functional diversity and reduced the contribution of a group of native taxa. In addition, among-sites functional diversity (beta FD) was successfully enlarged by restoration., Synthesis and applications. The lateral hydrological connectivity (LHC) represents a key parameter for explaining the functional diversity (FD) of macroinvertebrates in a floodplain ecosystem. Our results demonstrate that restoration-induced changes to functional diversity can be predicted. Controversially, restoration-induced enhancement of lateral hydrological connectivity increased the functional diversity of the alien macroinvertebrates. However, these species contributed only to a small part of the total macroinvertebrate functional diversity. We recommend that restoration programmes diversify the levels of lateral hydrological connectivity among the channels to ensure an optimal functional diversity at the floodplain scale. [ABSTRACT FROM AUTHOR]

To verify whether the variability in benthic invertebrate communities along the mountainous Czarny Dunajec River is mainly driven by the variation in hydromorphological or water quality, diversity of the communities was determined for 18 cross-sections with 1-5 low-flow channels and compared with the complexity of physical habitat conditions and with physico-chemical water quality. An increase in the complexity of flow pattern in the river was associated with increasing cross-sectional variability in physical habitat parameters. Distinct hydromorphological characteristics of the cross-sections with a given number of low-flow channels were especially pronounced if the analysis was limited to the parameters measured directly, whereas calculated complex hydraulic and sedimentary variables represented information overload. Taxonomic richness of the invertebrate communities was unrelated to physico-chemical water parameters, which consistently pointed to the high water quality. Instead, the richness positively correlated with a degree of variation in physical habitat parameters and was best predicted by the number of low-flow channels in a river cross-section. This study indicates that physical habitat complexity in a mountain river can be considered a proxy to the diversity of its invertebrate communities and that restoration of such complexity will be necessary for future recovery of invertebrate communities in impacted river sections. [ABSTRACT FROM AUTHOR]

1. Due to climate change, contemporary climate scenarios forecast an increase in extreme weather, which may have considerable impacts on the world's riverine ecosystems. Because the flow regime is a primary determinant of the structure and function of lotic ecosystems, changes in the weather could fundamentally alter these ecosystems through changes in hydrologic disturbance regimes. 2. In this paper, we use the abundance/biomass comparison (ABC) method, based on r/ K selection theory, and event probability distribution to characterise the responses of macroinvertebrates in Taiwan mountain streams to extreme floods. 3. Severe impacts on macroinvertebrates, resulting in a large shift in community structure toward r-selected taxa, usually were observed the year after extreme floods. 4. Macroinvertebrate communities dominated by K-selected taxa had more individuals with traits conferring resistance to flooding disturbance, while those dominated by r-selected taxa had more individuals with traits conferring resilience. 5. This relationship between the changes in flow regime and the ecological response of r- and K-selected taxa may be exploited to understand the potential effects of flood extremes in the future, and to keep decision makers informed about the ecological consequences of climate-mediated changes to hydrological regimes. [ABSTRACT FROM AUTHOR]

Summary 1. Freshwater ecosystems will be profoundly affected by global climate change, especially those in mountainous areas, which are known to be particularly vulnerable to warming temperatures. We modelled impacts of climate change on the distribution ranges of 38 species of benthic stream macroinvertebrates from nine macroinvertebrate orders covering all river zones from the headwaters to large river reaches. 2. Species altitudinal shifts as well as range changes up to the year 2080 were simulated using the A2a and B2a Intergovernmental Panel on Climate Change climate-warming scenarios. Presence-only species distribution models were constructed for a stream network in Germany's lower mountain ranges by means of consensus projections of four algorithms, as implemented in the BIOMOD package in R (GLM, GAM, GBM and ANN). 3. Species were predicted to shift an average of 122 and 83 m up in altitude along the river continuum by the year 2080 under the A2a and B2a climate-warming scenarios, respectively. No correlation between altitudinal shifts and mean annual air temperature of species' occurrence could be detected. 4. Depending on the climate-warming scenario, most or all (97% for A2a and 100% for B2a) of the macroinvertebrate species investigated were predicted to survive under climate change in the study area. Ranges were predicted to contract for species that currently occur in streams with low annual mean air temperatures but expand for species that inhabit rivers where air temperatures are higher. 5. Our models predict that novel climate conditions will reorganise species composition and community structure along the river continuum. Possible effects are discussed, including significant reductions in population size of headwater species, eventually leading to a loss of genetic diversity. A shift in river species composition is likely to enhance the establishment of non-native macroinvertebrates in the lower reaches of the river continuum. [ABSTRACT FROM AUTHOR]

Sampling benthic macroinvertebrates in large rivers has several limitations, arising not only from the selectivity of traditional sampling gears but also from difficulty in capturing organisms that inhabit the deeper zones and high current velocities. Considering the importance of benthic macroinvertebrates as a food resource for fishes, the sampling restrictions in sediment collection done by dredges, and the importance of surveying benthos biodiversity, the objective of this study was to evaluate the stomach contents of five commonly-occurring invertivorous fish species as a means of complementing a benthic macroinvertebrate inventory. Three sampling campaigns (fish and benthic macroinvertebrate) were conducted in a reach of the Araguari River (Minas Gerais, Brazil), approximately 9 km long and 90 m wide. Astyanax altiparanae Garutti & Britski 2000, Leporinus friderici (Bloch 1794), Leporinus amblyrhynchus Garavello & Britski 1987, Iheringichthys labrosus (Lütken 1874) and Pimelodus maculatus Lacepède 1803 were the fish species collected and studied. To determine benthic macroinvertebrate taxonomic richness, a total of 54 Van Veen sediment samples were obtained. We compared lists of the benthic taxa found in fish stomachs with those from the sediment samples. The differences in the taxonomic composition of the benthic macroinvertebrate communities between the sediment samples and each fish species stomachs contents were assessed through NMDS and ANOSIM analyses, using a Sorensen similarity index with the presence/absence of taxa data. Independent of sampling period, additional benthic macroinvertebrate families or classes were provided by identifying fish stomach contents. We found a total of 30 taxa in this study, including 5 unique taxa (or 17% of the total) in the sediment samples, 9 unique taxa (30%) in the stomach samples, and 16 taxa (53%) common to both. The NMDS and ANOSIM analyses showed a significant separation between Van Veen sediment samples and two fish species stomach contents- L. amblyrhynchus and P. maculatus. These results indicate that fish can be used as additional samplers and are an efficient method to complement the benthic taxonomic inventory obtained through traditional sediment sampling techniques in large areas, as river segments and catchments. [ABSTRACT FROM AUTHOR]

Rigorous and widely applicable indicators of biodiversity are needed to monitor the responses of ecosystems to global change and design effective conservation schemes. Among the potential indicators of biodiversity, those based on the functional traits of species and communities are interesting because they can be generalized to similar habitats and can be assessed by relatively rapid field assessment across eco-regions. Functional traits, however, have as yet been rarely considered in current common monitoring schemes. Moreover, standardized procedures of trait measurement and analyses have almost exclusively been developed for plants but different approaches have been used for different groups of organisms. Here we review approaches using functional traits as biodiversity indicators focussing not on plants as usual but particularly on animal groups that are commonly considered in different biodiversity monitoring schemes (benthic invertebrates, collembolans, above ground insects and birds). Further, we introduce a new framework based on functional traits indices and illustrate it using case studies where the traits of these organisms can help monitoring the response of biodiversity to different land use change drivers. We propose and test standard procedures to integrate different components of functional traits into biodiversity monitoring schemes across trophic levels and disciplines. We suggest that the development of indicators using functional traits could complement, rather than replace, the existent biodiversity monitoring. In this way, the comparison of the effect of land use changes on biodiversity is facilitated and is expected to positively influence conservation management practices. [ABSTRACT FROM AUTHOR]

Structure and function of the Serio River (northern Italy) ecosystem have been evaluated analyzing macroinvertebrate community functional traits. Starting from traits such as Functional Feeding Groups (FFG), Functional Habit Groups (FHG), voltinism and drift behavior, we determined values that can integrate direct measurements of ecosystem attributes and can be used in restoration planning. We collected invertebrates and environmental data in eight sites representative of the longitudinal succession of Serio River environments. High values for most of the ecosystem attributes, indicating good functionality, were confined in three sites of the upstream alpine sector, while downstream the ecosystem was severely impaired and colonized by non-specialized, pioneer communities. The intrinsic information given by ecosystem attributes helped aid the understanding of the health of specific ecosystem functions, thus leading to evaluation of priorities in restoration efforts. This methodology can be a complementary tool in river quality assessment if macroinvertebrate quantitative data are available. Particularly, it can be used in accordance with the new quantitative sampling protocols being adopted in the European Union, and it can define new metrics in a multimetric evaluation system. [ABSTRACT FROM AUTHOR]

The responses of ecological communities and ecosystems to increased rates of environmental change will be strongly influenced by variation in the diversity of community composition. Yet, our understanding of how diversity is affected by rising temperatures is inconclusive and mainly based on indirect evidence or short-term experiments. In our study, we analyse the diversity and species turnover of benthic epilithic communities within the thermal flume of a nuclear power plant at the Swedish coast. This flume covers the range of predicted future temperature rises. Species composition was significantly different between control sites and sites with higher temperatures. We found that temperature had little effect on the number of species in three functional groups (macroinvertebrates, benthic diatoms, and macrophytes, which here comprise multicellular algae and macroscopic colonies of unicellular algae and cyanobacteria), neither at single sampling dates nor summed for the entire observation year. However, species turnover significantly increased with increasing temperature for diatoms, macrophytes and invertebrates. Different temperature regimes resulted in significantly different species composition and indicator species. Thus, increasing temperatures in the thermal flume increased temporal beta-diversity and decreased compositional stability of communities, although observed richness did not change at any point in time. We highlight the need to investigate the consequences of such declines in compositional stability for functional stability of ecosystem processes. [ABSTRACT FROM AUTHOR]

1. Accurately assessing the effects of multiple human-caused stressors on freshwater (and other) ecosystems is an essential step in the development of efficient decision support tools for environmental managers. Our objective is to review potentials and limitations of the use of biological traits as indicators (BTIs) of multiple stressor effects on running water (i.e. lotic) ecosystems. 2. Pioneers in ecology provided mechanistic explanations for responses of alternative biological traits to a given stressor and for the action of habitat harshness as a trait filter. These ideas were subsequently integrated in theoretical ecological constructs (e.g. Habitat Templet Concept) that form the basis of the BTI approach. 3. To resolve the effects of multiple stressors on running waters requires multiple traits of a biologically diverse group of organisms such as lotic invertebrates. To meet this goal, however, recently created databases on the biological traits of lotic invertebrates must be expanded and unified. 4. Addressing the technical implementation of the BTI approach, we illustrate that anticipated problems with phylogenetic trait syndromes are seemingly less serious in reality and that presence–absence data of genera and few sample replicates are sufficient for accurate trait descriptions of invertebrate communities. 5. Current trends in politics demand that biomonitoring tools be effective at large scales, i.e. large-scale trait patterns of natural communities (i.e. at reference conditions) should be relatively stable. The trait composition of natural invertebrate communities is relatively stable at the scale of Europe and North America because trait filters of natural lotic habitats act similarly across large biogeographical units. 6. The mechanistic actions of stressors on the biological traits of invertebrates should facilitate a priori predictions, but the complexity of potential trait responses makes such predictions sometimes difficult. 7. To illustrate potentials and limitations of BTIs to identify a given stressor acting exclusively (or primarily), we examine the (i) use of functional feeding groups to indicate the action of various stressors and (ii) trait responses to an indirectly acting stressor (discharge variation) and to a more directly acting stressor (near-bottom flow). If the excessive use of specific traits for the indication of too many different stressors is avoided and a given stressor acts directly on traits as a priori predicted, reliable interpretations of trait responses can be achieved. 8. To illustrate how BTIs can identify individual stressors acting in combination, we examine three cases of multiple stressors: (i) heavy metal pollution in combination with cargo-ship traffic; (ii) eutrophication and fine sediment deposits associated with land use; and (iii) various stressors associated with climate change in combination with salinity. If the number of the assessed traits is sufficiently great and the action of each individual among the multiple stressors is not too weak, multiple traits can potentially resolve the effects of multiple stressors. 9. Thematic implications: if the expansion and unification of existing trait databases can be achieved, the rapidly growing knowledge about biological trait responses of lotic invertebrates to individual and multiple stressors should enable the identification of management priorities focused on: (i) individually acting stressors (manage stressor A at site X prior to stressor B at site Y); (ii) multiple stressors acting in different combinations at different sites (manage stressors A & B at site X prior to stressors C & D at site Y); and (iii) individual stressors acting in combination (manage stressor A prior to stressor B at site X). Thus, the BTI approach has the potential to inaugurate a new era in the biomonitoring of lotic (and other) ecosystems. [ABSTRACT FROM AUTHOR]

1. Climate-change effects on rivers and streams might interact with other pressures, such as pollution, but long-term investigations are scarce. We assessed trends among macroinvertebrates in 50 southern English streams in relation to temperature, discharge and water quality over 18 years (1989–2007). 2. Long-term records, coupled with estimates from inter-site calibrations of 3–4 years, showed that mean stream temperatures in the study area had increased by 2.1–2.9 °C in winter and 1.1–1.5 °C in summer over the 26 year period from 1980 to 2006, with trends in winter strongest. 3. While invertebrate assemblages in surface-fed streams were constant, those in chalk-streams changed significantly during 1989–2007. Invertebrate trends correlated significantly with temperature, but effects were spurious because (i) assemblages gained taxa typical of faster flow or well-oxygenated conditions, contrary to expectations from warming; (ii) more invertebrate families increased in abundance than declined and (iii) concomitant changes in water quality (e.g. declining orthophosphate, ammonia and biochemical oxygen demand), or at some sites changes in discharge, explained more variation in invertebrate abundance and composition than did temperature. 4. These patterns were reconfirmed in both group- and site-specific analyses. 5. We conclude that recent winter-biased warming in southern English chalk-streams has been insufficient to affect invertebrates negatively over a period of improving water quality. This implies that positive management can minimize some climate-change impacts on stream ecosystems. Chalk-stream invertebrates are sensitive, nevertheless, to variations in discharge, and detectable changes could occur if climate change alters flow pattern. 6. Because climatic trends now characterize many inter-annual time-series, we caution other investigators to examine whether putative effects on ecological systems are real or linked spuriously to other causes of change. [ABSTRACT FROM AUTHOR]

1. Effective environmental management requires a sound understanding of the causal mechanisms underlying the relationship of species with their environment. Mechanistic explanations linking species and environment are ultimately based on species traits. Many tools for ecological assessment and biomonitoring lack such explanations. Elsewhere, we have defined life-history strategies, based on the interrelations between species traits and their functional implications. 2. This study tests the hypothesis that life-history strategies represent different solutions to particular ecological problems, thus connecting species and their environment through species traits. Data on aquatic macroinvertebrates in a variety of waterbodies were analysed in terms of life-history strategies. These waterbodies differed in environmental conditions and macroinvertebrate assemblages. Solutions to the ecological problems present in each type of water body were expected to be reflected in the abundance of (species exhibiting) different life-history strategies. 3. Results show clear differences in strategy composition between the different water types, which could be related to the prevailing environmental conditions through mechanistic explanations. For example, species with a long period of juvenile development and a synchronized emergence of short-lived adults were most dominant in large mesotrophic waterbodies with stable and predictable environmental conditions. In contrast, species that have a rapid development and spread successive reproduction attempts over a longer time period were most abundant in waterbodies with fluctuating and less predictable environmental conditions. 4. Differences in strategy composition provide insight into the prevailing environmental conditions related to temporal predictability, and habitat favourability, from the perspective of the species themselves. By reducing diverse species assemblages to a small number of strategies, representing easily interpretable relationships, this approach may be useful in environmental quality assessment programmes, including those required by the European Water Framework Directive. Based on mechanistic explanations, life-history strategies may generate testable predictions and guide future research. Further research may focus on expanding life-history strategies to include other species groups and ecosystems. [ABSTRACT FROM AUTHOR]

Water level management in Mississippi River Pool 25 differentially influences off-channel habitats in the mid-pool and lower pool. Hydrologic models indicate lower pool off-channel habitats dry with greater frequency and duration compared to similar habitats at mid-pool. We examined the influence of this contrasting hydrology on substrate characteristics, organic matter, macroinvertebrate, and fish communities in off-channel habitats during 2001–2003. Benthic organic matter standing stocks were stable in mid-pool habitats but lower pool values were variable because of annual differences in moist-soil vegetation production. Generally, small-bodied and multivoltine invertebrate taxa had high community biomass and dominated lower pool habitats, whereas longer-lived and large-bodied taxa were more abundant and had higher community biomass in mid-pool habitats having longer hydroperiods. Fish communities were dominated by cyprinids in both habitats, and mid-pool habitats tended to be higher in overall species richness. Unique fish taxa were collected in each pool, with primarily rheophilic forms in mid-pool habitats and limnophilic forms in lower pool habitats. Results indicate that contrasting hydrology associated with a mid-pool control point directly and indirectly influences biological communities in off-channel habitats. Further, management regimes that promote hydrologic diversity in off-channel habitats may enhance biological diversity at larger spatial and temporal scales. [ABSTRACT FROM AUTHOR]

Is there a relationship between the abundance of organisms and particular biological attributes? To assess this old, yet still acutely debated key question of ecology, we have used large databases on 312 stream macroinvertebrate genera (from 27 orders) that describe (1) invertebrate abundance at 527 least human-impacted European stream sites, (2) 11 biological traits (size, life-history, food, among others) described in 61 biological trait categories (BTCs; e.g. small, intermediate or large size) and (3) 14 attributes indicating specialization (AISs; e.g. species richness, size and food diversity). We applied interactive procedures to obtain models (for BTCs, AISs and a mixture of both descriptions) explaining as much as possible of the abundance variability of the genera with the lowest number of significant and ecologically meaningful attributes and assessed the predictive power of these models (in crosswise validations) by comparing predicted and observed abundances. Mean European invertebrate abundance increased with BTC affinities favouring viability in stream systems (e.g. attachment to the stream bottom to resist the flow, aquatic passive dispersal with the flow, exploitation of abundant food sources) and decreased with BTC affinities disfavouring this viability (e.g. drag force increase associated with larger body size, flow exposure associated with aerial respiration). Abundance consistently decreased with specialization of the genera (e.g. low species richness, oddity of their overall BTC profile from an “average” European genus). The model including a mixture of a few BTCs and AISs had the greatest predictive power: it predicted 35% of the observed abundance (ln-transformed) variability of the genera; these predictions were marginally affected by taxonomy (using orders as categorical variables). We conclude that a better appreciation of the influence of the examined taxonomic diversity, number and type of biological attributes, environmental system and spatial scale could enable abundance predictions using different sets of biological attributes for different taxonomic groups and systems. [ABSTRACT FROM AUTHOR]

1. The power of selected biological invertebrate traits for discriminating different types of human impact (heavy metal pollution and cargo-ship traffic) were tested using ecological reasoning and linear Discriminant Function Analysis (DFA). 2. Frequency distributions of individual traits and categories of traits from 68 least impacted river reaches (LIRRs) and 304 impacted river reaches were used to define simple assessment rules based on ecological reasoning for specific impairments in large European rivers. In calibration, a maximum of three variables with a priori predictions and two different impairment threshold levels were used. Similarly, DFA was performed on the same variables included in the ecological reasoning approach, but also on all available traits or trait categories. 3. Validation with an independent data set (40 LIRRs, 291 variously impacted river reaches) and using the ecological reasoning approach showed that 75–78% of the reaches were correctly assign with rules on all impact types, 35–57% with rules on heavy metal pollution and 78–93% with rules on cargo-ship traffic. By comparison, validation showed that DFA performed globally poorer than the ecological reasoning approach. In addition, the performance of the rules based on ecological reasoning remained stable, whereas DFA performance changed between calibration and validation. 4. Although not defined for this purpose, our study provided alarming evidence regarding the impact of cargo-ship traffic on invertebrate communities in river reaches. Reaches with cargo-ship traffic were found to have more genera with long life cycles that reproduce repeatedly by ovoviviparity and have a sessile life. 5. The performance of our trait-based approach to correctly assign reaches to either least impacted or impacted conditions should promote further research on the topic across larger geographic areas (without regionalization) and across smaller stream types to provide a powerful biomonitoring tool that fulfils current European Union directives. [ABSTRACT FROM AUTHOR]