Climate effects on prey vulnerability modify expectations of predator responses to short- and long-term climate fluctuations

Climate changes affect the distribution and abundance of organisms, often via changes in species interactions. Most animals experience predation, and a number of models have investigated how climate fluctuations can influence predator–prey dynamics by affecting prey abundance through changes in resource availability. However, field studies have shown that prey vulnerability is a key feature determining the outcome of predator– prey interactions, which also varies with climatic conditions, via changes in prey body condition or in habitat characteristics (e.g. vegetation cover). In this theoretical work, we explore, with large mammals of African savannas in mind, how the interplay between climate-induced changes in prey abundance and climate-induced changes in prey vulnerability affects the immediate and long-term responses of predator populations. We account for prey body condition and habitat effects on prey vulnerability to predation. We show that predictions on how predator abundance responds to climate fluctuations differ depending on how climate influences prey vulnerability (habitat characteristics vs. prey body condition). We discuss how species traits influence the relative importance of the different sources of vulnerability. For example, our results suggest that populations of cursorial predators (such as spotted hyaenas) are expected to fare better than populations of ambush predators (such as African lions) in African ecosystems that will be characterised by an aridification. This study highlights the importance of understanding, and accounting for, the vulnerability factors associated to a given predator–prey pair, and improves our comprehension of predator–prey relationships in a changing climate.We thank C. Wilmers for providing the code of the published model that serves as the basis of ours. In addition, this work benefited from the computing cluster platform of the Centre d’Ecologie Fonctionnelle et Evolutive and from Biosphere, the IFB cloud for life sciences. We thank Bruno Spataro and Stéphane Delmotte from the LBBE computing services for their help in using computing facilities. Finally, we thank two reviewers for their fruitful comments on a previous draft of this manuscript.This work was partly funded by the Agence Nationale de la Recherche (project Landthirst ANR-16-CE02-0001- 01 and FUTURE-PRED ANR-18-CE02-0005-01) and was further supported by a grant from the “Ministère français de l’Enseignement supérieur, de la Recherche et de l’Innovation” through the “Ecole Doctorale E2M2” of “Université Claude Bernard Lyon 1”.The Agence Nationale de la Recherche and a grant from the “Ministère français de l’Enseignement supérieur, de la Recherche et de l’Innovation” through the “Ecole Doctorale E2M2” of “Université Claude Bernard Lyon 1”.https://www.frontiersin.org/journals/ecology-and-evolution#am2022Mammal Research InstituteZoology and Entomolog

Premier inventaire des communautés de diatomées périphytiques des tributaires du lac Ichkeul, Tunisie

International audienceAn initial inventory of diatom biodiversity at 12 sites draining into Lake Ichkeul, northern Tunisia, was performed in summer 2014, together with the characterisation of metal pollution status by analysing trace metal concentrations to determine Water Quality Indices. The maximum values of Fe, Mn, Sb, Zn, Cu and Pb were all below the national and international standard, except for Fe in Hammam Ben Abbes thermal spring and Sb in Wadi Tinja, indicating that the surface water of the Ichkeul basin was largely acceptable. Diatom community composition and specific descriptors, including quantification of morphological alterations and mortality, were used to diagnose environmental stress. High abundances of Achnanthidium minutissimum (Kützing) Czarnecki were observed at the Fe-rich site, which could reflect a response to metal contamination. Diatoms were stressed mostly by the influence of temperature and salinity, which drove species composition and increased mortality. Further research is required on the ecology of diatoms in Ichkeul thermal springs. The use of diatoms as indicators of ecosystem health in the Ichkeul area requires additional knowledge of diatom diversity in the ecoregion

An innovative and comprehensive study to identify relevant emerging contaminants in French surface waters

International audienceAs part of the implementation of the National Action Plan on Micropollutants in the Aquatic Environment, the French Ministry of Ecology a large national screening study took place in 2012 in France. INERIS was charged with the design and technical implementation of this project for surface water. For the selection and prioritisation of the watch list compounds the National Expert Group for prioritisation of substances (CEP) decided to adopt the criteria of the NORMAN methodology for prioritisation of emerging substances.That methodology uses a decision tree that first classifies chemicals into six categories, on the basis of the existing knowledge gaps and the actions to be taken to fill them. The priority within each category is then ranked on the basis of specific indicators, which allows a score to be calculated. For surface water three campaigns were performed on water matrix and one in sediments at about 159 sampling points. Grab sampling was applied on all sites. In addition, passive samplers (POCIS) were deploied in 20 rivers in order to allow the implementation of bioassays. Sampling was carried out according to AQUAREF’s (National Reference Laboratory for Aquatic Environment) technical specifications and a unique courier was selected for transport of samples to the laboratories. The analytical work for a given group of compounds was performed by one single laboratory in order to ensure data comparability. Four academic laboratories were selected for chemical analyses. 170 substances were finally selected for chemical analysis in water and sediment.The benefits of this innovative approach for identification of relevant emerging contaminants are i) a unique prioritisation scheme (NORMAN Network) applied at French national level for substance and site selection; ii) Information on occurrence, source and variability for 170 substances (50 000 robust analytical data items) ; iii) an efficient method for data collection, validation and exploitation thanks to a unique data collection template and an exhaustive set of metadata; iv) the application of effect-based tools to classify 20 sites of various quality; to characterise site contamination a panel of in vitro and in vivo bioassays were deployed as well as biomarkers to assess impacts of pollutants in wild population of fish.The results contributed to the selection of substances to be integrated in the national river basins monitoring programmes

An innovative and comprehensive study to identify relevant emerging contaminants in French surface waters

International audienceAs part of the implementation of the National Action Plan on Micropollutants in the Aquatic Environment, the French Ministry of Ecology a large national screening study took place in 2012 in France. INERIS was charged with the design and technical implementation of this project for surface water. For the selection and prioritisation of the watch list compounds the National Expert Group for prioritisation of substances (CEP) decided to adopt the criteria of the NORMAN methodology for prioritisation of emerging substances.That methodology uses a decision tree that first classifies chemicals into six categories, on the basis of the existing knowledge gaps and the actions to be taken to fill them. The priority within each category is then ranked on the basis of specific indicators, which allows a score to be calculated. For surface water three campaigns were performed on water matrix and one in sediments at about 159 sampling points. Grab sampling was applied on all sites. In addition, passive samplers (POCIS) were deploied in 20 rivers in order to allow the implementation of bioassays. Sampling was carried out according to AQUAREF’s (National Reference Laboratory for Aquatic Environment) technical specifications and a unique courier was selected for transport of samples to the laboratories. The analytical work for a given group of compounds was performed by one single laboratory in order to ensure data comparability. Four academic laboratories were selected for chemical analyses. 170 substances were finally selected for chemical analysis in water and sediment.The benefits of this innovative approach for identification of relevant emerging contaminants are i) a unique prioritisation scheme (NORMAN Network) applied at French national level for substance and site selection; ii) Information on occurrence, source and variability for 170 substances (50 000 robust analytical data items) ; iii) an efficient method for data collection, validation and exploitation thanks to a unique data collection template and an exhaustive set of metadata; iv) the application of effect-based tools to classify 20 sites of various quality; to characterise site contamination a panel of in vitro and in vivo bioassays were deployed as well as biomarkers to assess impacts of pollutants in wild population of fish.The results contributed to the selection of substances to be integrated in the national river basins monitoring programmes

Methodology for profiling anti-androgen mixtures in river water using multiple passive samplers and bioassay-directed analyses

The identification of endocrine disrupting chemicals in surface waters is challenging as they comprise a variety of structures which are often present at nanomolar concentrations and are temporally highly variable. Hence, a holistic passive sampling approach can be an efficient technique to overcome these limitations. In this study, a combination of 4 different passive samplers used for sampling polar (POCIS Apharm and POCIS Bpesticide) and apolar compounds (LDPE low density polyethylene membranes, and silicone strips) were used to profile anti-androgenic activity present in river water contaminated by a wastewater effluent. Extracts of passive samplers were analysed using HPLC fractionation in combination with an in vitro androgen receptor antagonist screen (YAS). Anti-androgenic activity was detected in extracts from silicone strips and POCIS A/B at (mean ± SD) 1.1 ± 0.1 and 0.55 ± 0.06 mg flutamide standard equivalents/sampler respectively, but was not detected in LDPE sampler extracts. POCIS samplers revealed higher selectivity for more polar anti-androgenic HPLC fractions compared with silicone strips. Over 31 contaminants were identified which showed inhibition of YAS activity and were potential anti-androgens, and these included fungicides, germicides, flame retardants and pharmaceuticals. This study reveals that passive sampling, using a combination of POCIS A and silicone samplers, is a promising tool for screening complex mixture of anti-androgenic contaminants present in surface waters, with the potential to identify new and emerging structures with endocrine disrupting activity

How can water quality be improved when the urban waste water directive has been fulfilled? A case study of the Lot river (France)

International audienceThe Lot river, a major tributary of the downstream Garonne river, the largest river on the Northern side of the Pyrenees Mountains, was intensively studied in the 1970s. A pioneering program called “Lot Rivière Claire” provided a diagnosis of water quality at the scale of the whole watershed and proposed an ambitious program to manage nutrient pollution and eutrophication largely caused by urban wastewater releases. Later on, the implementation of European directives from 1991 to 2000 resulted in the nearly complete treatment of point sources of pollution in spite of a doubling of the basin’s population. At the outlet of the Lot river, ammonium and phosphate contamination which respectively peaked to 1 mg N-NH4 L−1 and 0.3 mg P-PO4 L−1 in the 1980s returned to much lower levels in recent years (0.06 mg N-NH4 L−1 and 0.02 mg P-PO4 L−1), a reduction by a factor 15. However, during this time, nitrate contamination has regularly increased since the 1980s, from 0.5 to 1.2 mg N-NO3 L−1 in average, owing to the intensification of agriculture and livestock farming. Application of the Riverstrahler model allowed us to simulate the water quality of the Lot drainage network for the 2002–2014 period. We showed that, with respect to algal requirements, phosphorus and silica are well balanced, but nitrogen remains largely in excess over phosphorus and silica. This imbalance can be problematic for the ecological status of the water bodies. Using the model, for simulating various scenarios of watershed management, we showed that improvement of urban wastewater treatment would not result in any significant change in the river’s water quality. Even though arable land occupies a rather limited fraction of the watershed area, only the adoption of better farming practices or more radical changes in the agro-food system could reverse the trend of increasing nitrate contamination