Linking new national active biomonitoring data with stream macroinvertebrate communities suggests large-scale effects of toxic contamination on freshwater ecosystems.

Since recent years, an increasingly large number of toxic chemicals enters watercourses threatening freshwater biodiversity. But ecological studies still poorly document the quantitative patterns linking exposure to complex mixture of toxic chemicals and species communities' integrity in the field. In this context, French monitoring authorities have recently deployed at a national scale in situ biotests using the feeding inhibition of the crustacean Gammarus as toxicity indicator.

River flow intermittence influence biodiversity-stability relationships across spatial scales: Implications for an uncertain future.

Climate change is increasing the proportion of river networks experiencing flow intermittence, which in turn reduces local diversity (i.e., α-diversity) but enhances variation in species composition among sites (i.

Identifying the impact of toxicity on stream macroinvertebrate communities in a multi-stressor context based on national ecological and ecotoxicological monitoring databases.

In situ bioassays are used to measure the harmful effects induced by mixtures of toxic chemicals in watercourses. In France, national-scale biomonitoring data are available including invertebrate surveys and in-field chemical toxicity measures with caged gammarids to assess environmental toxicity of mixtures of chemicals. The main objective of our study is to present a proof-of-concept approach identifying possible links between in-field chemical toxicity, stressors and the ecological status.

A metric-based analysis on the effects of riparian and catchment landuse on macroinvertebrates.

Woody riparian vegetation along rivers and streams provides multiple functions beneficial for aquatic macroinvertebrate communities. They retain fine sediments, nutrients and pesticides, improve channel hydromorphology, control water temperature and primary production through shading and provide leaves, twigs and large wood. In a recent conceptual model (Feld et al.

Quantification of multi-scale links of anthropogenic pressures with PAH and PCB bioavailable contamination in French freshwaters.

Aquatic ecosystems are exposed to multiple environmental pressures including chemical contamination. Polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs) are persistent organic pollutants (POPs) known as preoccupying substances for the environment. Active biomonitoring (ABM) is a surveillance method for polluted aquatic ecosystems measuring bioavailable contamination.

Lack of definition of mathematical terms in ecology: The case of the sigmoid class of functions in macro-ecology.

Defining mathematical terms and objects is a constant issue in ecology; often definitions are absent, erroneous, or imprecise. Through a bibliographic prospection, we show that this problem appears in macro-ecology (biogeography and community ecology) where the lack of definition for the sigmoid class of functions results in difficulties of interpretation and communication. In order to solve this problem and to help harmonize papers that use sigmoid functions in ecology, herein we propose a comprehensive definition of these mathematical objects.

ARPEGES: A Bayesian Belief Network to Assess the Risk of Pesticide Contamination for the River Network of France.

Pesticides are priority concerns in aquatic risk assessment due to their widespread use, ongoing development of new molecules, and potential effects from short- and long-term exposures to aquatic life. Water quality assessments are also challenged by contrasting pesticide behaviors (e.g.

How to quantify the links between bioavailable contamination in watercourses and pressures of anthropogenic land cover, contamination sources and hydromorphology at multiple scales?

Active biomonitoring permits the quantification of biological exposure to chemicals through measurements of bioavailable concentrations in biota and biological markers of toxicity in organisms. It enables respective comparison of the levels of contamination between sites and sampling campaigns. Caged gammarids are recently proposed as relevant probes for measuring bioavailable contamination in freshwater systems.

Multisubstance Indicators Based on Caged Gammarus Bioaccumulation Reveal the Influence of Chemical Contamination on Stream Macroinvertebrate Abundances across France.

Most anthropogenic stressors affecting freshwater systems are qualitatively known. However, the quantitative assessment of contaminant exposure and effects to aquatic communities is still difficult, limiting the understanding of consequences on aquatic ecosystem functioning and the implementation of effective management plans. Here, multisubstance indicators based on caged gammarid bioaccumulated contamination data are proposed (for metals and persistent organic pollutants, POPs) to map the bioavailable contamination level of freshwater ecosystems at a large spatial scale.

At what scale and extent environmental gradients and climatic changes influence stream invertebrate communities?

In a context of increasing landscape modifications and climatic changes, scale hierarchy becomes an ever more crucial issue to integrate in the analysis of drivers and stressors of biological communities, especially in river networks. To cope with this issue, we developed (i) spatial hierarchical models of functional diversity of stream invertebrate communities to assess the relative influence of local- vs. regional-scale factors in structuring community assembly, and (ii) analysis of metacommunity elements to determine the ecological processes behind the structuring.

Metapopulation modelling of riparian tree species persistence in river networks under climate change.

Floodplain landscapes are highly fragmented by river regulation resulting in habitat degradation and flood regime perturbation, posing risks to population persistence. Climate change is expected to pose supplementary risks in this context of fragmented landscapes, and especially for river systems adaptation management programs are developed. The association of habitat quality and quantity with the landscape dynamics and resilience to human-induced disturbances is still poorly understood in the context of species survival and colonization processes, but essential to prioritize conservation and restoration actions.

Unravelling river system impairments in stream networks with an integrated risk approach.

Rivers are complex systems for which it is hard to make reliable assessments of causes and responses to impairments. We present a holistic risk-based framework for river ecosystem assessment integrating all potential intervening processes and functions. Risk approaches allow us to deal with uncertainty both in the construction of indicators for magnitude of stressors and in the inference of environmental processes and their impairment.