Species specific responses to stressors hamper Trichoptera recovery.

Worldwide, aquatic biodiversity is severely threatened as a result of anthropogenic pressures such as pollution, habitat destruction and climate change. Widescale legislation resulted in reduced nutrient- and pesticide loads, and restoration measures allowed modest recovery of freshwater biodiversity. However, from 2010 onwards, recovery in the otherwise unrestored aquatic habitats stagnated.

Sludge degradation, nutrient removal and reduction of greenhouse gas emission by a Chironomus-Azolla wastewater treatment cascade.

Wastewater treatment plants (WWTPs) are a point source of nutrients, emit greenhouse gases (GHGs), and produce large volumes of excess sludge. The use of aquatic organisms may be an alternative to the technical post-treatment of WWTP effluent, as they play an important role in nutrient dynamics and carbon balance in natural ecosystems. The aim of this study was therefore to assess the performance of an experimental wastewater-treatment cascade of bioturbating macroinvertebrates and floating plants in terms of sludge degradation, nutrient removal and lowering GHG emission.

Four decades of region- and species-specific trends in lowland stream Ephemeroptera abundance.

Lowland stream ecosystems are under threat from climate change, industrialization, urbanization, and intensive agriculture. Since the 1980s, improvements in water quality have led to an increase in lowland stream biodiversity. Despite restoration efforts, however, further recovery is often hampered by the presence of region-specific (combinations of) stressors, and species-specific stressor responses.

Combining Passive Sampling and Dosing to Unravel the Contribution of Hydrophobic Organic Contaminants to Sediment Ecotoxicity.

Contaminated sediments are ubiquitous repositories of pollutants and cause substantial environmental risks. Results of sediment bioassays remain difficult to interpret, however, as observed effects may be caused by a variety of (un)known stressors. This study aimed therefore to isolate the effects of hydrophobic organic contaminants from other (non)chemical stressors present in contaminated sediments, by employing a newly developed passive sampling-passive dosing (PSPD) test.

Phylogenetic analysis of museum specimens of houting Coregonus oxyrinchus shows the need for a revision of its extinct status.

According to the IUCN Red List the anadromous houting Coregonus oxyrinchus is categorized as 'extinct'. However, this extinct status might be incorrect because taxonomic difference between C. oxyrinchus and the closely related C.

The recovery of European freshwater biodiversity has come to a halt.

Owing to a long history of anthropogenic pressures, freshwater ecosystems are among the most vulnerable to biodiversity loss. Mitigation measures, including wastewater treatment and hydromorphological restoration, have aimed to improve environmental quality and foster the recovery of freshwater biodiversity. Here, using 1,816 time series of freshwater invertebrate communities collected across 22 European countries between 1968 and 2020, we quantified temporal trends in taxonomic and functional diversity and their responses to environmental pressures and gradients.

Enlarging the Arsenal of Test Species for Sediment Quality Assessment.

Since only a few standard benthic test species are available for sediment quality, our study aimed to employ multiple test species representing different sensitivity categories in the quality assessment of contaminated sediments. To this end three macroinvertebrate species, Sericostoma personatum (caddisfly, sensitivity category 10), Asellus aquaticus (isopod, category 3) and Chironomus riparius (chironomid, category 2), were exposed to sediments originating from various contamination sources in whole sediment bioassays using intact sediment cores. The agricultural sediment caused insect mortality, the agricultural and urban sediment caused isopod growth reduction and the urban and Wastewater Treatment Plant (WWTP) sediment affected chironomid emergence time.

Wastewater treatment plant contaminant profiles affect macroinvertebrate sludge degradation.

Disposal of the overwhelming amounts of excess wastewater treatment plant (WWTP) sludge is an increasing financial and environmental problem, and new methods to reduce the amount of excess sludge are therefore required. In the natural environment, interactions between multiple macroinvertebrate detritivores mediate the degradation of organic matter. Macroinvertebrates may thus also be able to degrade WWTP sludge, but may meanwhile be impacted by the associated contaminants.

Contribution of sediment contamination to multi-stress in lowland waters.

Water bodies in densely populated lowland areas are often impacted by multiple stressors. At these multi-stressed sites, it remains challenging to quantify the contribution of contaminated sediments. This study, therefore, aimed to elucidate the contribution of sediment contamination in 16 multi-stressed drainage ditches throughout the Netherlands.

Organic matter degradation and redistribution of sediment associated contaminants by benthic invertebrate activities.

The fate of sediment associated compounds is the combined result of chemical properties and biological activities. Yet, studies simultaneously addressing the effects of biota on the redistribution and bioaccumulation of contaminants are scarce. Our aim was therefore to assess the effect of benthic invertebrate activities on organic matter degradation and the redistribution of metals and Polycyclic Aromatic Hydrocarbons (PAHs) in contaminated sediment.

A Bayesian network to simulate macroinvertebrate responses to multiple stressors in lowland streams.

Aquatic ecosystems are affected by multiple environmental stressors across spatial and temporal scales. Yet the nature of stressor interactions and stressor-response relationships is still poorly understood. This hampers the selection of appropriate restoration measures.

Functional traits explain crayfish invasive success in the Netherlands.

Biological invasions by nonindigenous species can have negative effects on economies and ecosystems. To limit this impact, current research on biological invasions uses functional traits to facilitate a mechanistic understanding of theoretical and applied questions. Here we aimed to assess the role of functional traits in the progression of crayfish species through different stages of invasion and determine the traits associated with invasive success.

Eutrophication induces shifts in the trophic position of invertebrates in aquatic food webs.

Changes in the ecological stoichiometry of primary producers may have considerable implications for energy and matter transfer in food webs. We hypothesized that nutrient enrichment shifts the trophic position of omnivores towards herbivory, as the nutritional quality of primary producers increases. This hypothesis was tested by analyzing the ecological stoichiometry and stable isotope signature of primary producers and a wide range of aquatic macroinvertebrates, including primary consumers (herbivores) and secondary consumers (both potential omnivores and strict carnivores), along a eutrophication gradient in an agricultural landscape.

Responses of resources and consumers to experimental flow pulses in a temporary Mediterranean stream.

Determining the resistance and resilience of resources and benthic invertebrates connected to instream refuges and species re-colonization in post-flood periods may help to elucidate mechanisms behind community recovery. This experiment simulated flow pulses in a small temporary stream in an extremely wet year, using upstream control and downstream flooded reaches at three sites in order to assess community resistance and resilience (benthos and drift), and analyse resources (periphyton and benthic organic matter) and invertebrates at pre- and post-flood time periods. The hyporheos was sampled in order to explore species exchanges with benthos.

Advancements in effect-based surface water quality assessment.

Legally-prescribed chemical monitoring is unfit for determining the pollution status of surface waters, and there is a need for improved assessment methods that consider the aggregated risk of all bioavailable micropollutants present in the aquatic environment. Therefore, the present study aimed to advance effect-based water quality assessment by implementing methodological improvements and to gain insight into contamination source-specific bioanalytical responses. Passive sampling of non-polar and polar organic compounds and metals was applied at 14 surface water locations that were characterized by two major anthropogenic contamination sources, agriculture and wastewater treatment plant (WWTP) effluent, as well as reference locations with a low expected impact from micropollutants.

Over forty years of lowland stream restoration: Lessons learned?

Stream restoration efforts have increased, but the success rate is still rather low. The underlying reasons for these unsuccessful restoration efforts remain inconclusive and need urgent clarification. Therefore, the aim of the present study was to evaluate over 40 years of stream restoration to fuel future perspectives.

Land use affects lowland stream ecosystems through dissolved oxygen regimes.

The aim of the present study was to assess the impact of surrounding land use on the structure and functioning of lowland stream ecosystems. To this end, five different land use types were selected (forest, extensive grassland, intensive grassland, cropland and wastewater treatment plant) each represented by four replicate streams, in which diel dissolved oxygen concentrations were recorded, sediment and water quality parameters were measured and macroinvertebrate community composition was determined. Chironomus sp.

Responses of macroinvertebrate communities to land use specific sediment food and habitat characteristics in lowland streams.

The input of land use specific organic matter into lowland streams may impact sediment characteristics in terms of food resources and habitat structure, resulting in differences in macroinvertebrate community composition. Therefore, we investigated to what extent land use specific sediment food and habitat characteristics structure macroinvertebrate communities. To this purpose linear multiple regression models were constructed, in which macroinvertebrate biotic indices were considered as response variables and sediment characteristics as predictor variables, analysed in 20 stream stretches running through five different land use types.

Limitations of trait-based approaches for stressor assessment: The case of freshwater invertebrates and climate drivers.

The appeal of trait-based approaches for assessing environmental vulnerabilities arises from the potential insight they provide into the mechanisms underlying the changes in populations and community structure. Traits can provide ecologically based explanations for observed responses to environmental changes, along with predictive power gained by developing relationships between traits and environmental variables. Despite these potential benefits, questions remain regarding the utility and limitations of these approaches, which we explore focusing on the following questions: (a) How reliable are predictions of biotic responses to changing conditions based on single trait-environment relationships? (b) What factors constrain detection of single trait-environment relationships, and how can they be addressed? (c) Can we use information on meta-community processes to reveal conditions when assumptions underlying trait-based studies are not met? We address these questions by reviewing published literature on aquatic invertebrate communities from stream ecosystems.

Quantifying cumulative stress acting on macroinvertebrate assemblages in lowland streams.

Macroinvertebrates in lowland streams are exposed to multiple stressors from the surrounding environment. Yet, quantifying how these multiple stressors impact macroinvertebrate assemblages is challenging. The aim of this study was to develop a novel method to quantify the cumulative stress acting on macroinvertebrate assemblages in lowland streams.

Effect-based nationwide surface water quality assessment to identify ecotoxicological risks.

A large portion of the toxic effects observed in surface waters cannot be attributed to compounds regularly measured by water authorities. Hence, there is an urgent need for an effect-based monitoring strategy that employs bioassays to identify environmental risks. The aim of the present study was to perform an effect-based nationwide water quality assessment to identify ecotoxicological risks in a wide variety of surface waters.

The significance of refuge heterogeneity for lowland stream caddisfly larvae to escape from drift.

The process of macroinvertebrate drift in freshwater lowland streams is characterized by dislodgement, drift distance and subsequent return to the bottom. Refuges are important to all drift phases, since they may help larvae to avoid dislodgement and to escape from drift, even more so if the refuge structure is complex and heterogeneous. The aim of the present study was therefore to determine the influence of refuge heterogeneity on the ability of caddisfly larvae to return to the bottom from drift and to avoid secondary dislodgement.

Reintroduction of freshwater macroinvertebrates: challenges and opportunities.

Species reintroductions - the translocation of individuals to areas in which a species has been extirpated with the aim of re-establishing a self-sustaining population - have become a widespread practice in conservation biology. Reintroduction projects have tended to focus on terrestrial vertebrates and, to a lesser extent, fishes. Much less effort has been devoted to the reintroduction of invertebrates into restored freshwater habitats.

Nationwide screening of surface water toxicity to algae.

According to the European Water Framework Directive (WFD), chemical water quality is assessed by monitoring 45 priority substances. However, observed toxic effects can often not be attributed to these priority substances, and therefore there is an urgent need for an effect-based monitoring strategy that employs bioassays to identify environmental risk. Algal photosynthesis is a sensitive process that can be applied to identify the presence of hazardous herbicides in surface water.