Résumé
This study has been performed in the framework of a research program aiming to develop a low-cost aerial sensor for the monitoring of cyanobacteria in freshwater ecosystems that could be used for early detection. Several empirical and mechanistic remote-sensing tools have been already developed and tested at large scales and have proven useful in monitoring cyanobacterial blooms. However, the effectiveness of these tools for early detection is hard to assess because such work requires the detection of low concentrations of characteristic pigments amid complex ecosystems exhibiting several confounding factors (turbidity, blooms of other species, etc.). We developed a framework for performing high-throughput measurements of the absorbance and reflectance of small volumes (∼ = 20 mL) of controlled mixtures of phytoplankton species and studied the potential of this framework to validate remote-sensing proxies of cyanobacteria concentration. The absorption and reflectance spectra of single and multiple cultures carried a specific signal that allowed for the quantitative analysis of culture mixes. This specific signal was shown to be related to known pigment absorbance spectra. The concentrations of chlorophyll-a and -b, phycocyanin and phycoerythrin could be obtained from direct absorbance measurements and were correlated with the concentration obtained after pigment extraction (R2 ≥ 0.96 for all pigments). A systematic test of every possible two-band and three-band normalized difference between optical indices was then performed, and the coincidental correlation with chlorophyll-b (absent in cyanobacteria) was used as an indicator of non-specificity. Two-band indices were shown to suffer from non-specificity issues and could not yield strong and specific relationships with phycocyanin or phycoerythrin (maximum R2 0.8).
Auteurs, date et publication :
Auteurs Gabriel Hmimina , Florence D. Hulot , Jean François Humbert , Catherine Quiblier , Kevin Tambosco , Bruno J. Lemaire , Brigitte Vinçon-Leite , Louise Audebert , Kamel Soudani
Publication : Water Research
Date : 2019
Volume : 148
Pages : 504-514
Catégorie(s)
#CNRS #Ecotron IleDeFrance #ENS #PLANAQUAAuteurs, date et publication :
Auteurs François Mainié , Arnaud Huguet , Alice Breban , Gérard Lacroix , Christelle Anquetil , Sylvie Derenne
Date : 2025
Volume : 17
Catégorie(s)
#⛔ No DOI found #CNRS #ENS #PLANAQUARésumé
Some parasites are known to bioaccumulate some environmental pollutants within their host. We hypothesized that these parasites may be beneficial for their hosts in polluted environments. We experimentally increased long-term (five weeks) exposure to polycyclic aromatic hydrocarbons (PAHs, three levels: 0.1X, 1X, 10X environmental exposure) in European chubs (Squalius cephalus) that were naturally infected or uninfected with acanthocephalan parasites. We monitored PAHs levels in fish tissues, as well as oxidative stress, telomere length and condition indices. Although parasite infection did not significantly reduce the levels of PAHs and PAH metabolites in host tissues, host oxidative status was explained by parasitism and pollution levels. Oxidative damage increased with parasitism in fish exposed to low PAH levels (0.1X) but decreased in infected fish at higher PAH exposure (10X), thus corroborating our hypothesis. Meanwhile, antioxidant capacity did not differ in response to parasite infection nor PAHs exposure. Despite this imbalance in oxidative status, experimental increase in PAH levels did not compromise telomere length, body condition, or survival in infected and uninfected fish. This study provides the first experimental evidence that the outcome of host-parasite interactions can shift from negative to positive as pollutant exposure increases.
Auteurs, date et publication :
Auteurs Noëlie Molbert , Simon Agostini , Fabrice Alliot , Frédéric Angelier , Clotilde Biard , Beatriz Decencière , Mathieu Leroux-Coyau , Alexis Millot , Cécile Ribout , Aurélie Goutte
Publication : Ecotoxicology and Environmental Safety
Date : 2021
Volume : 219
Pages : 112322
Catégorie(s)
#CNRS #ENS #PLANAQUARésumé
The Ponto-Caspian freshwater amphipod Dikerogammarus villosus has colonized most of the water bodies of continental Europe where it causes strong structural alterations in recipient communities that can lead to changes in ecosystem-level processes, mainly because of a strong predatory behaviour. Most of the D. villosus populations from the invaded range have been found infected with the co-introduced microsporidian parasite Cucumispora dikerogammari, known to decrease the predation rate of its host. Infection might thus mitigate the ecological impact of D. villosus and we wanted to test this assumption using the comparative functional response approach. We compared the relationship between resource use and resource availability (i.e. the functional response, FR) of D. villosus, either with infected individuals or not, to that of two non-invasive gammarids: Gammarus pulex and Echinogammarus berilloni. With infected individuals included, D. villosus displayed a higher FR than the two non-invasive gammarids. Although this effect was not significant, C. dikerogammari infection tended to alter the FR of D. villosus with a slight decrease in attack rate and handling time, resulting in a less steep initial slope and a higher asymptote, respectively. Removing infected D. villosus from the dataset did not affect the FR comparison with G. pulex but suppressed the difference in FR with E. berilloni. Although we cannot exclude the role of sample size reduction in this effect, this suggests that C. dikerogammari infection might increase the predation pressure on local prey populations in case of species replacement between D. villosus and E. berilloni. From a more general perspective, our study illustrates how parasites may alter our capacity to predict invasive species impacts from FR comparisons.
Auteurs, date et publication :
Auteurs Corentin Iltis , Thierry Spataro , Rémi Wattier , Vincent Médoc
Publication : Biological Invasions
Date : 2018
Volume : 20
Issue : 3
Pages : 619-632
Catégorie(s)
#CNRS #ENS #PLANAQUARésumé
Through this study, we established the taxonomic status of seven strains belonging to the genus Pectobacterium (A477-S1-J17T, A398-S21-F17, A535-S3-A17, A411-S4-F17, A113-S21-F16, FL63-S17 and FL60-S17) collected from four different river streams and an artificial lake in south-east France between 2016 and 2017. Ecological surveys in rivers and lakes pointed out different repartition of strains belonging to this clade compared to the closest species, Pectobacterium aquaticum . The main phenotypic difference observed between these strains and the P. aquaticum type strain was strongly impaired growth with rhamnose as the sole carbon source. This correlates with three different forms of pseudogenization of the l-rhamnose/proton symporter gene rhaT in the genomes of strains belonging to this clade. Phylogenetic analysis using gapA gene sequences and multi locus sequence analysis of the core genome showed that these strains formed a distinct clade within the genus Pectobacterium closely related to P. aquaticum. Digital DNA–DNA hybridization (dDDH) and average nucleotide identity (ANI) values showed a clear discontinuity between the new clade and P. aquaticum . However, the calculated values are potentially consistent with either splitting or merging of this new clade with P. aquaticum . In support of the split, ANI coverages were higher within this new clade than between this new clade and P. aquaticum . The split is also consistent with the range of observed ANI or dDDH values that currently separate several accepted species within the genus Pectobacterium . On the basis of these data,strains A477-S1-J17T, A398-S21-F17, A535-S3-A17, A411-S4-F17, A113-S21-F16, FL63-S17 and FL60-S17 represent a novel species of the genus Pectobacterium , for which the name Pectobacterium quasiaquaticum sp. nov. is proposed. The type strain is A477-S1-J17T (=CFBP 8805T=LMG 32181T).,
Auteurs, date et publication :
Auteurs Hajar Ben Moussa , Jacques Pédron , Claire Bertrand , Amandine Hecquet , Marie-AnneYR 2021 Barny
Publication : International Journal of Systematic and Evolutionary Microbiology
Date : 2025
Volume : 71
Issue : 10
Pages : 005042
Catégorie(s)
#ANR-Citation #CNRS #ENS #PLANAQUAAuteurs, date et publication :
Auteurs Andrew J. Helmstetter , Alexander S. T. Papadopulos , Javier Igea , Tom J. M. Van Dooren , Armand M. Leroi , Vincent Savolainen
Publication : Nature Communications
Date : 2016
Volume : 7
Pages : 11271
Catégorie(s)
#CNRS #ENS #PLANAQUAAuteurs, date et publication :
Auteurs Neil E. Coughlan , James W.E. Dickey , Jaimie T.A. Dick , Vincent Médoc , Monica McCard , Gérard Lacroix , Sarah Fiorini , Alexis Millot , Ross N. Cuthbert
Publication : Science of The Total Environment
Date : 2025
Volume : 843
Pages : 156876
Catégorie(s)
#ANR-Citation #CNRS #ENS #PLANAQUARésumé
Unravelling evolution-by-environment interactions on the gut microbiome is particularly relevant considering the unprecedented level of human-driven disruption of the ecological and evolutionary trajectories of species. Here, we aimed to evaluate whether an evolutionary response to sizeselective mortality influences the gut microbiome of medaka (Oryzias latipes), how environmental conditions interact with the genetic background of medaka on their microbiota, and the association between microbiome diversity and medaka growth-related traits. To do so, we studied two lineages of medaka with known divergence in foraging efficiency and life history raised under antagonistic size-selective regimes for 10 generations (i.e. the largest or the smallest breeders were removed to mimic fishing-like or natural mortality). In pond mesocosms, the two lineages were subjected to contrasting population density and light intensity (used as proxies of resource availability). We observed significant differences in the gut microbiome composition and richness between the two lines, and this effect was mediated by light intensity. The bacterial richness of fishing-like medaka (small-breeder line) was reduced by 34% under low-light conditions compared to high-light conditions, while it remained unchanged in natural mortality-selected medaka (largebreeder line). However, the observed changes in bacterial richness did not correlate with changes in adult growth-related traits. Given the growing evidence about the gut microbiomes importance to host health, more in-depth studies are required to fully understand the role of the microbiome in size-selected organisms and the possible ecosystem-level consequences.
Auteurs, date et publication :
Auteurs Charlotte Evangelista , Stefaniya Kamenova , Beatriz Diaz Pauli , Joakim Sandkjenn , Leif Asbjørn Vøllestad , Eric Edeline , Pål Trosvik , Eric Jacques De Muinck
Publication : Peer Community Journal
Date : 2023
Volume : 3
Pages : e72
Catégorie(s)
#CNRS #ENS #PLANAQUARésumé
Gut microbiome diversity and functions are jointly shaped by the host’s genetic background and environmental conditions, but the consequences of this interaction are still unclear. Unravelling the effect of the interaction between evolution and environment on the gut microbiome is particularly relevant considering the unprecedented level of human-driven disruption on the ecological and evolutionary trajectories of species. Here, we aimed to evaluate whether size-selective mortality influences the gut microbiome of medaka (Oryzias latipes), how environment conditions modulate the effect of the genetic background of medaka on their microbiota, and the association between microbiome diversity and medaka fitness. To do so, we studied two lineages of medaka that were raised under antagonistic size-selective regimes for 10 generations (i.e. the largest or the smallest breeders were removed to mimic fishing-like or natural mortality). In pond mesocosms, the two lineages were subjected to contrasting population density and light intensity (i.e. used as a proxy of primary production, hence resource availability). We observed significant differences in the gut microbiome composition and richness between the two lines, and this effect was mediated by light intensity. Indeed, the bacterial richness of fishing-like medaka (small-breeder line) was reduced by 34% under low-light conditions compared to high-light conditions, while it remained unchanged in natural mortality-selected medaka (large-breeder line). However, the observed changes in bacterial richness did not correlate with changes in growth rate or body condition, possibly due to functional redundancy among the microbial taxa residing in the gut. Given the growing evidence about the gut microbiomes importance to host health, more in-depth studies are required to fully understand the role of the microbiome in size-selected organisms and the possible ecosystem-level consequences.
Auteurs, date et publication :
Auteurs C. Evangelista , S. Kamenova , B. Diaz Pauli , J. Sandkjenn , L. A. Vøllestad , E. Edeline , P. Trosvik , EJ de Muinck
Date : 2023
Catégorie(s)
#CNRS #ENS #PLANAQUAAuteurs, date et publication :
Auteurs Jaimie T.A. Dick , Ciaran Laverty , Jack J. Lennon , Daniel Barrios-O'Neill , Paul J. Mensink , J. Robert Britton , Vincent Médoc , Pieter Boets , Mhairi E. Alexander , Nigel G. Taylor , Alison M. Dunn , Melanie J. Hatcher , Paula J. Rosewarne , Steven Crookes , Hugh J. MacIsaac , Meng Xu , Anthony Ricciardi , Ryan J. Wasserman , Bruce R. Ellender , Olaf L.F. Weyl
Publication : Journal of Applied Ecology
Date : 2025
Volume : 54
Issue : 4
Pages : 1259-1267