Résumé
Man-made sounds are now recognized as a pervasive pollutant, and impacts on wildlife have been researched for many years. However, less knowledge is available on certain species, particularly small freshwater invertebrates, which are abundant, highly diversified, and occupy key positions in food webs. Also, it is not clear whether the responses to noise observed at the level of individuals have consequences on communities. A mesocosm investigation was performed to assess the response of a freshwater planktonic community to chronic motorboat noise. Noise was expected to disturb trophic links within the community and particularly the consumption of cladocerans by dipteran larvae. To test this hypothesis, the functional response of Chaoborus larvae feeding on Daphnia was derived, and their behavior during the foraging process was recorded in microcosms (aquariums). Although noise did not induce obvious alteration in the community composition, a significant increase in the abundance of cladocerans was found that was not supported by the results of the microcosm investigation, showing no difference in Chaoborus functional response or behavior between the noisy and noiseless conditions. The results of this chapter suggest that the composition of freshwater zooplankton and particularly cladocerans is likely to be altered by chronic noise, with further investigations needed to understand the mechanisms. They also illustrate how scaling up the effects of noise from individual responses to community remains difficult.
Auteurs, date et publication :
Auteurs Emilie Rojas , Camille Desjonquères , Simon Agostini , Sarah Fiorini , Béatriz Decencière , Michael Danger , Vincent Felten , Vincent Médoc , Arthur N. Popper , Joseph Sisneros , Anthony D. Hawkins , Frank Thomsen
Date : 2025
Pages : 1-17
Catégorie(s)
#CNRS #ENS #PLANAQUARésumé
Only a few studies have examined responses of grassland functional diversity to management and major environmental gradients, in order to address the question of whether grassland use can promote functional divergence. For five grassland sites in Israel, Portugal, the Czech Republic, Mediterranean France, and the French Alps, where traditional grassland management is being abandoned, we quantified community-weighted means (CWM) and functional divergence (FDvg) for the three Leaf–Height–Seed (LHS) traits, individually and in combination. Responses of CWM and FDvg to land use were analyzed by mixed linear models with aridity, phosphorus, fertility, and the fractions of grasses and annuals as covariates.
Auteurs, date et publication :
Auteurs Sandra Lavorel , Francesco de Bello , Karl Grigulis , Jan Lepš , Eric Garnier , Helena Castro , Jiri Dolezal , Carly Godolets , Fabien Quétier , Aurélie Thébault
Publication : Israel Journal of Ecology & Evolution
Date : 2025
Volume : 57
Issue : 1-2
Pages : 53-72
Catégorie(s)
#CNRS #Lautaret #UGARésumé
Earthworms contribute to a wide range of ecosystem services provided by the soil. Nevertheless, synecology of these organisms is still not properly elucidated especially in terms of species interactions. The aim of the present study was to determine the effects of anecic earthworm species interactions on their individual biomass. These effects were measured using three epi-anecic species, Lumbricus rubellus rubellus (Hoffmeister, 1843), Lumbricus centralis (Bouché, 1972), Lumbricus terrestris (Linné 1758), and three strict-anecic species, Aporrectodea caliginosa meridionalis (Bouché, 1972), Aporrectodea nocturna (Evans, 1946), Aporrectodea giardi (Savigny, 1826). Twenty-one pairs of individuals were established following five assemblages: monospecific pairwise assemblages of epi- and strict-anecic earthworms (2 × 3 treatments), bispecific pairwise assemblages within epi- and within strict-anecic earthworms (2 × 3 treatments) and bispecific pairwise assemblages with one epi- and one strict-anecic earthworm (3 × 3 treatments). Treatments were maintained in mesocosms for 30 days under controlled conditions (food provided at the soil surface at the beginning of the experiment) and changes in the earthworm individual biomass were measured. Strict-anecic earthworms in monospecific or bispecific assemblages maintained their initial biomass. In contrast, epi-anecic earthworms exhibited an increase of 12.4% and 23.7% of their biomass in monospecific and bispecific assemblages, respectively. In bispecific assemblages combining one epi- and one strict-anecic earthworm, epi-anecic earthworms solely gained biomass leading to a total increase of a 6.9%. Surprisingly, the biomass' changes were not homogenous within the two sub-categories as the six earthworm species exhibited species-specific responses. The greatest increases in individual biomass were recorded for epi-anecic earthworms in the bispecific assemblages. This study provides further evidence for the distinction between the two anecic sub-categories, as it indicates that species interactions is positive only for epi-anecic earthworm biomass.
Auteurs, date et publication :
Auteurs Kevin Hoeffner , Cécile Monard , Daniel Cluzeau , Mathieu Santonja
Publication : Applied Soil Ecology
Date : 2019
Volume : 144
Pages : 8-11
Catégorie(s)
#CNRS #EcoGenO #Université de RennesRésumé
The capacity of a Quercus pubescens forest to resist recurrent drought was assessed on an in situ experimental platform through the measurement of a large set of traits (ecophysiological and metabolic) studied under natural drought (ND) and amplified drought (AD) induced by partial rain exclusion. This study was performed during the third and fourth years of AD, which correspond to conditions of moderate AD in 2014 and harsher AD in 2015, respectively. Although water potential (Ψ) and net photosynthesis (Pn) were noticeably reduced under AD in 2015 compared to ND, trees showed similar growth and no oxidative stress. The absence of oxidative damage could be due to a strong accumulation of α-tocopherol, suggesting that this compound is a major component of the Q. pubescens antioxidant system. Other antioxidants were rather stable under AD in 2014, but slight changes started to be observed in 2015 (carotenoids and isoprene) due to harsher conditions. Our results indicate that Q. pubescens could be able to cope with AD, for at least 4 years, likely due to its antioxidant system. However, growth decrease was observed during the fifth year (2016) of AD, suggesting that this resistance could be threatened over longer periods of recurrent drought.
Auteurs, date et publication :
Auteurs Amélie Saunier , Elena Ormeño , Michel Havaux , Henri Wortham , Brigitte Ksas , Brice Temime-Roussel , James D. Blande , Caroline Lecareux , Jean-Philippe Mévy , Anne Bousquet-Mélou , Thierry Gauquelin , Catherine Fernandez
Publication : Plant, Cell & Environment
Date : 2018
Volume : 41
Issue : 10
Pages : 2299-2312
Catégorie(s)
#CNRS #FORET O3HPAuteurs, date et publication :
Auteurs Solenn Stoeckel , Ronan Becheler , Luis Portillo-Lemus , Marilyne Harang , Anne-Laure Besnard , Gilles Lassalle , Romain Causse-Védrines , Sophie Michon-Coudouel , Daniel J. Park , Bernard J. Pope , Eric J. Petit , Dominique Barloy
Publication : Peer Community Journal
Date : 2025
Volume : 4
Catégorie(s)
#CNRS #EcoGenO #Université de RennesRésumé
Global climate changes such as prolonged duration and intensity of drought can lead to adverse ecological consequences in forests. Currently little is known about soil microbial community responses to such drought regimes in tropical forests. In this study, we examined the resistance and resilience of topsoil prokaryotic communities to a prolongation of the dry season in terms of diversity, community structure and co-occurrence patterns in a French Guianan tropical forest. Through excluding rainfall during and after the dry season, a simulated prolongation of the dry season by five months was compared to controls. Our results show that prokaryotic communities increasingly diverged from controls with the progression of rain exclusion. Furthermore, prolonged drought significantly affected microbial co-occurrence networks. However, both the composition and co-occurrence networks of soil prokaryotic communities immediately ceased to differ from controls when precipitation throughfall returned. This study thus suggests modest resistance but high resilience of microbial communities to a prolonged drought in tropical rainforest soils.
Auteurs, date et publication :
Auteurs Lingjuan Li , Catherine Preece , Qiang Lin , Laëtitia M Bréchet , Clément Stahl , Elodie A Courtois , Erik Verbruggen
Publication : FEMS Microbiology Ecology
Date : 2025
Volume : 97
Issue : 9
Pages : fiab116
Catégorie(s)
#CNRS #FORET NouraguesRésumé
In this study, we evaluate the relationships between the photochemical reflectance index (PRI) and light-use efficiency (LUE) based on eight years of continuous in situ measurements acquired on a half-hourly basis for PRI, NDVI (Normalized Difference Vegetation Index), the main micrometeorological variables and net CO2 exchange data in two deciduous and evergreen mature forests. More specifically, the objectives of this study include investigating the daily, seasonal, and interannual variations of PRI and LUE; linking PRI variations to the main influencing meteorological and eco-physiological variables; and evaluating the performance of PRI as a remote-sensing proxy of LUE under different environmental conditions. The data analysis was performed at different time scales within the season using moving temporal windows and between years. On a seasonal scale, statistical analyses revealed positive relationships between PRI and absorbed photosynthetically active radiation (aPAR) and negative relationships between PRI and LUE. Over shorter periods of a few days, the signs of these relationships remained unchanged; however, their correlations were strongly improved. The highest correlations were most often observed over periods characterized by clear or slightly overcast skies. However, all the periods of clear skies did not involve improvements in the relations of PRI vs. aPAR or PRI vs. LUE. Temporal variations of the intercept (called PRI0 in this study) of PRI vs. aPAR regressions suggest the presence of a temporal trend that may reflect seasonal changes of the biochemical characteristics of the canopy. Regardless of the cause of this trend, it is important to note that once PRI0 was subtracted from the measured PRI, the correlations between the corrected PRI and LUE for each year were significantly improved, and a stable multi-year model was obtained. Nevertheless, further studies are required to explain the temporal changes of PRI0 during the season and to develop a more accurate disentangling approach that would make PRI-based remote-sensing of ecosystem light-use efficiency less sensitive to confounding factors related to spatial and temporal changes in the structural and biochemical properties of the canopy.
Auteurs, date et publication :
Auteurs Kamel Soudani
Publication : Remote Sensing of Environment
Date : 2025
Pages : 12
Catégorie(s)
#CNRS #FORET PuechabonRésumé
Trace elements in the blood of crocodilians and the factors that influence their concentrations are overall poorly documented. However, determination of influencing factors is crucial to assess the relevance of caimans as bioindicators of environmental contamination, and potential toxicological impact of trace elements on these reptiles. In the present study, we determined the concentrations of 14 trace elements (Ag, As, Cd, Cr, Co, Cu, Fe, Hg, Pb, Mn, Ni, Se, V, and Zn) in the blood of four French Guiana caiman species (the Spectacled Caiman Caiman crocodilus [n = 34], the Black Caiman Melanosuchus niger [n = 25], the Dwarf Caiman Paleosuchus palpebrosus [n = 5] and the Smooth-fronted Caiman Paleosuchus trigonatus [n = 20]) from 8 different sites, and further investigated the influence of individual body size and stable isotopes as proxies of foraging habitat and trophic position on trace element concentrations. Trophic position was identified to be an important factor influencing trace element concentrations in the four caiman species and explained interspecific variations. These findings highlight the need to consider trophic ecology when crocodilians are used as bioindicators of trace element contamination in environmental studies.
Auteurs, date et publication :
Auteurs Jérémy Lemaire , François Brischoux , Oliver Marquis , Rosanna Mangione , Stéphane Caut , Maud Brault-Favrou , Carine Churlaud , Paco Bustamante
Publication : Science of The Total Environment
Date : 2022
Volume : 837
Pages : 155846
Catégorie(s)
#ANR-Citation #CNRS #FORET NouraguesAuteurs, date et publication :
Auteurs Karl Grigulis , Sandra Lavorel , Ute Krainer , Nicolas Legay , Catherine Baxendale , Maxime Dumont , Eva Kastl , Cindy Arnoldi , Richard D. Bardgett , Franck Poly , Thomas Pommier , Michael Schloter , Ulrike Tappeiner , Michael Bahn , Jean-Christophe Clément , Michael Hutchings
Publication : Journal of Ecology
Date : 2025
Volume : 101
Issue : 1
Pages : 47-57
Catégorie(s)
#CNRS #Lautaret #UGARésumé
Animals relying on uncertain, ephemeral and patchy resources have to regularly update their information about profitable sites. For many tropical amphibians, widespread, scattered breeding pools constitute such fluctuating resources. Among tropical amphibians, poison frogs (Dendrobatidae) exhibit some of the most complex spatial and parental behaviors—including territoriality and tadpole transport from terrestrial clutches to ephemeral aquatic deposition sites. Recent studies have revealed that poison frogs rely on spatial memory to successfully navigate through their environment. This raises the question of when and how these frogs gain information about the area and suitable reproductive resources. To investigate the spatial patterns of pool use and to reveal potential explorative behavior, we used telemetry to follow males of the territorial dendrobatid frog Allobates femoralis during tadpole transport and subsequent homing. To elicit exploration, we reduced resource availability experimentally by simulating desiccated deposition sites. We found that tadpole transport is strongly directed towards known deposition sites and that frogs take similar direct paths when returning to their home territory. Frogs move faster during tadpole transport than when homing after the deposition, which probably reflects different risks and costs during these two movement phases. We found no evidence for exploration, neither during transport nor homing, and independent of the availability of deposition sites. We suggest that prospecting during tadpole transport is too risky for the transported offspring as well as for the transporting male. Relying on spatial memory of multiple previously discovered pools appears to be the predominant and successful strategy for the exploitation of reproductive resources in A. femoralis. Our study provides for the first time a detailed description of poison frog movement patterns during tadpole transport and corroborates recent findings on the significance of spatial memory in poison frogs. When these frogs explore and discover new reproductive resources remains unknown.
Auteurs, date et publication :
Auteurs Kristina B. Beck , Matthias-Claudio Loretto , Max Ringler , Walter Hödl , Andrius Pašukonis
Publication : PeerJ
Date : 2017
Volume : 5
Pages : e3745