Nicolas Hette-Tronquart

French Agency for Biodiversity · Research, development, and innovation

Dorsal white muscle is the standard tissue analysed in fish trophic studies using stable isotope analyses. However, sampling white muscle often implies the sacrifice of fish. Thus, we examined whether the non-lethal sampling of fin tissue can substitute muscle sampling in food web studies. Analysing muscle and fin δ(15)N and δ(13)C values of 466 Eu...

Food-chain length (FCL) is commonly used in ecological investigations to gain insight into how ecosystems function. Several studies have investigated the mechanisms underlying FCL patterns, but none has specifically examined the effect of temperature variability. In river ecosystems, water temperature variability can modify community structure, ind...

The upstream–downstream gradient (UDG) is a key feature of streams. For instance food webs are assumed to change from upstream to downstream. We tested this hypothesis in a small European river catchment (937 km 2), and examined whether food web modifications are related to structural (i.e. food web composition) or functional changes (i.e. alterati...

The continuous increase of anthropogenic activities reinforces their stress on aquatic ecosystems (from continental to marine ecosystems) that are the most altered ecosystems on Earth. To evaluate the risk of ecosystem decline toward human alterations, the concept of “ecological vulnerability” was developed to help managers to prioritize conservati...

Renewable energies have been identified as one of the main actions to reduce greenhouse gas emissions. After a significant phase of development for wind energy, solar energy is now developing rapidly, including in natural habitats. The project « Envoltaïque SE » aims to determine how solar panels installed in wooded habitats (forests, scrubland) co...

This document presents a brief review of the literature on the impact of photovoltaic farms on chiropterans. It then summarizes scientific results that have been published or are in the process of being published. Finally, it proposes a standardized protocol and recommendations to be implemented on photovoltaic projects.

The negative impacts of anthropogenic climate change (e.g., global warming, extreme weather events, food insecurity, etc.), are among the driving factors behind the phase-out of fossil fuels and shift to renewable energies that do not emit greenhouse gases, such as wind (Msigwa et al., 2022). Consequently, wind energy is becoming a major component...

Recent advances in molecular biomonitoring open new horizons for aquatic ecosystem assessment. Rapid and cost-effective methods based on organismal DNA or environmental DNA (eDNA) now offer the opportunity to produce inventories of indicator taxa that can subsequently be used to assess biodiversity and ecological quality. However, the integration o...

La directive cadre européenne sur l’eau a placé l’hydrobiologie au cœur de l’évaluation de la qualité des milieux aquatiques. Dans ce contexte, la bioindication est redevenue une discipline très active de l’écologie, soutenue par des enjeux sociétaux forts. Dans cet article, les auteurs présentent un aperçu des différents aspects du contexte dans l...

Les approches en écologie fonctionnelle ouvrent aujourd’hui de nouvelles perspectives dans le domaine du diagnostic écologique. C’est le cas par exemple du critère de la redondance fonctionnelle que les auteurs de cet article ont appliqué aux communautés de poissons pour évaluer leur sensibilité fonctionnelle à la perte d’espèces, et au-delà, mesur...

Background: This study aims to describe and test a tiered approach for assessing compliance to Environmental Quality standards (EQSs) for priority substances in biota in line with the European Water Framework Directive. This approach is based on caged gammarids and trophic magnification factors (TMFs) at the first tier, with fish analysed at the se...

Background : This study aims to describe and test a tiered approach for assessing compliance to Environmental Quality standards (EQSs) for priority substances in biota in line with the European Water Framework Directive. This approach is based on caged gammarids and trophic magnification factors (TMFs) at the first tier, with fish analysed at the s...

The work of Sheppard et al. (2018) relies on the strong assumption that isotopic niche is equal to trophic niche. Here I raise three main concerns showing that classic hypotheses built upon trophic niche cannot be directly interpreted in isotopic space. Future studies should always keep isotopic and trophic niches distinct.

Trophic ecology is the study of feeding interactions and food acquisition by organisms. It includes the causes and consequences of those behaviours at all levels of biological organisation. As a field of research, it crosses many disciplinary boundaries and provides knowledge that is pertinent to many other areas of ecology. Here we list and catego...

As part of the landscape, streams are influenced by land use. Here, we contributed to the understanding of the biological impacts of land use on streams, investigating how landscape effects vary with spatial scales (local vs. regional). We adopted a food web approach integrating both biological structure and functioning, to focus on the overall eff...

In order to assess the ecological status of ecosystems it is necessary to include their functional features into the evaluation process. Currently, the available bioindicators do not fully meet this objective and new indicators are needed. One way of developing such indicators could be to use trophic diversity, as it integrates both structural and...

We briefly remind the issues of the project 20 (follow up of the project 33) and give more details on the aim and problematics of the project (effect of both natural and anthropogenic environmental factors, selection of food-web metrics, and comparison between the responses of food-web metrics and bioindicators). We present the progress of the proj...

Currently there is a need for direct measurements of biological functioning to evaluate the ecological status of aquatic ecosystems. One possibility could be the study of food web features using stable isotope analysis. The project 33 deals with this issue in the case of lotic ecosystems and focuses on 3 topics: 1- how do the natural environmental...

To date, biological indicators used to assess river health are mainly based on assemblage structure (species composition), and poorly incorporate the functional features of ecosystems. Food webs, as networks of species linked by trophic interactions, integrate both structural (via the species) and functional (via the interactions) features of ecosy...

We briefly remind the issues and give more details on the aim and problematics of the project (effect of environmental factors, influence of anthropogenic pressures and development of isotopic metrics). We present the research activities conducted in 2013 and 2014, focusing on the design of experiments (state after the sampling), and on the progres...

It is clear that the numbers of species and individuals are key features of a food web. Still, very few studies investigate how species richness influences trophic diversity. We conducted a natural experiment to examine this question, using streams as ecosystem models, and taking advantage of the sites’ location along the upstream downstream gradie...

We briefly remind the national and european issues that lead to develop functional approaches of stream ecosystems. We review the state of the art in trophic ecology to give some background understanding of the recent issues concerning stream food webs. We describe the three main methods currently used to study the stream food webs leading us to un...

Riparian vegetation is of paramount importance for stream ecology but the underlying mechanisms are still poorly understood. For instance, riparian vegetation plays a key role in determining the nature and amount of autochthonous and allochthonous organic matter entering the streams. In temperate regions, both aquatic primary production and terrest...

L’étude des réseaux trophiques est un prérequis à la compréhension du fonctionnement des écosystèmes. Cependant, les déterminants potentiels des réseaux trophiques (disponibilité des ressources, stabilité et taille de l’écosystème) restent discutés. Dans ce contexte, 3 nouvelles questions portant sur les réseaux trophiques des cours d’eau sont abor...

Burrowing benthic organisms promote water and solute fluxes across the sediment–water interface. Water and solutes penetrate the burrow walls and are transported into/out of the sediment when organisms flush their burrows with overlying water. Few studies have been done to investigate bioirrigation under shifting environmental conditions. We experi...

Ecological management of aquatic ecosystems implies understanding the impacts of human activities on their functioning. Trophic relationships, which constitute a major ecosystem function, could be particularly sensitive to human land use in watersheds. To test this hypothesis, we sampled 18 sites located in 10 tributaries of the Orge river catchmen...

Trophic interactions are essential to address functional biodiversity. Concerning stream ecosystems, three major non-exclusive hypotheses are put forward to explain variations of food web organisation and complexity; i.e. ecosystem size, energy supply and environmental stability. Recent studies have confirmed that environmental stability plays a ke...

Although the influence of stream thermal budgets on trophic relationships is one of the decisive issues for developing population dynamic models of cryophilic fish species (such as Cottus gobio), it is still poorly known. In this project, we studied the effect of water temperature on trophic position of bullhead C. gobio. Five temperate streams (Be...