108 research outputs found
The response of microphytobenthos to physical disturbance, herbicide, and titanium dioxide nanoparticles exposure
The research leading to these results received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement No 730984, ASSEMBLE Plus project. AJW was funded by the John Templeton Grant 60501, âPutting the Extended Evolutionary Synthesis to the Testâ. DMP and AJB were supported by the NERC Blue-coast award (NE/N016009/1).The microphytobenthos that form transient biofilms are important primary producers in intertidal, depositional habitats, yet we have only a limited understanding of how they respond to the cumulative impacts of the growing range of anthropogenic stressors to which they are exposed. We know even less about how the temporal alignment of exposure â such as duration and exposure sequence â may affect the response. Estuarine biofilms were cultured in mesocosms and exposed to the herbicide glyphosate and titanium dioxide (TiO2) nanoparticles in different sequences (glyphosate-first or TiO2-first), as well as in the presence and absence of physical disturbance. We found that at environmentally realistic chemical concentrations, the order of exposure was less important than the total stressor scenario in terms of impacts on key functional attributes and diatom community structure. Physical disturbance did not have an impact on functional attributes, regardless of exposure sequence.Publisher PDFPeer reviewe
Identification of microbial exopolymer producers in sandy and muddy intertidal sediments by compound-specific isotope analysis
Towards the development of ecosystem-based indicators of mangroves functioning state in the context of the EU water framework directive
European Water Framework Directive is enforced in five tropical French Oversea Territories where mangroves are present. Developing bioindication tools to support the ecosystem-based management approach of the Directive is needed. A series of expert workshops was organized and led to the proposal of a strategy and of an applied research program to develop bioindication tools. The proceedings of the workshops are presented as a case study, as this is the first time such an integrative ecosystem-based approach is proposed in mangroves, combining structural and functional aspects, from forest structure to benthic community functioning
Towards a better understanding of the effects of self-shading on Fucus serratus populations
The importance of the vertical structure of vegetation cover for the functioning, management and conservation of ecosystems has received particular attention from ecologists in the last decades. Canopy architecture has many implications for light extinction coefficient, temperature variation reduction, self-shading which are all key parameters for the structuring and functioning of different ecosystems such as grasslands [1,2], forests [3,4], phytoplankton communities [5, 6], macroalgal populations [7] and even underwater animal forests such as octocoral communities [8]
Les tardigrades, des animaux Ă toute Ă©preuve ?
National audienceLa Terre s'est formĂ©e il y a 4,5 milliards d'annĂ©es mais nous ne le savons que depuis la seconde partie du XXe siĂšcle. Alors que nous recensions quelques milliers d'espĂšces au milieu du XVIIIe siĂšcle, on en identifie aujourd'hui deux millions, et l'on estime que ce nombre ne reprĂ©sente que 20 % de la richesse totale encore Ă dĂ©crire ! Quant Ă l'humain, si l'on pensait que son histoire se rĂ©sumait Ă une succession de deux ou trois espĂšces sur deux millions d'annĂ©es, on dĂ©couvre aujourd'hui que dix fois plus d'espĂšces d'hominines ont existĂ©, sur sept millions d'annĂ©es. Chaque dĂ©couverte augmente le niveau de complexitĂ© de ce que l'on sait et Ă©largit le pĂ©rimĂštre de ce qu'il reste Ă connaĂźtre.La vitalitĂ© de la recherche bĂ©nĂ©ficie de multiples Ă©volutions techniques, mĂ©thodologiques et conceptuelles. Si l'histoire naturelle favorise depuis toujours les approches interdisciplinaires, quelques-unes â comme la cosmochimie, l'archĂ©ozoologie ou encore la palĂ©ogĂ©nĂ©tique â ont connu un grand Ă©lan ces derniĂšres dĂ©cennies. Le perfectionnement des outils de mesure, de l'imagerie scientifique ou des instruments de sĂ©quençage gĂ©nĂ©tique donne un nouveau souffle Ă des Ă©tudes engagĂ©es de longue date. Enfin, de nouvelles façons de faire et de penser Ă©mergent, comme en tĂ©moignent l'essor des sciences participatives et l'apparition de nouveaux concepts (holobionte, anthropocĂšne, One Health, etc.).Voici un aperçu des foisonnants travaux menĂ©s au MusĂ©um national d'histoire naturelle, qui remettent en cause la façon dont chacun d'entre nous se situe dans l'univers, dans la nature, dans la sociĂ©tĂ©. Des premiers indices de vies aux biofilms des caniveaux urbains, les contributions ici rĂ©unies relatent d'Ă©tonnantes petites et grandes dĂ©couvertes. Entre miscellanĂ©es et synthĂšse, cet ouvrage donne Ă voir la diversitĂ© d'un patrimoine qu'il nous incombe de dĂ©couvrir et de dĂ©fendre
Biofilms, tapis et agrégats microbiens : vers une vision unificatrice
The complexity of the mechanisms underlying the fixation and installation of microorganisms on a given surface, or substrate, is such that it is often impossible to predict which community will develop. The nature of the substrates, the physico-chemical environment, the surface roughness, seasonal fluctuations and various anthropogenic forcings all determine the interactions and make each biofilm unique.However, this uniqueness is only apparent. Whatever the complexity of the biofilm considered, its general structure will be invariable and will contain a certain number of elements of similarity with, in foreground, the secretion of extracellular polymers. These secretions support a number important ecosystem functions and services that are common to all microbial communities. My research aims to answer fundamental questions about the determinism of the fixation of microorganisms, their development and their roles in the functioning of ecosystems.This document summarises my research on microbial biofilms, mats and aggregates and attempts to build a unifying vision of these diverse communities
Biofilms, tapis et agrégats microbiens : vers une vision unificatrice
The complexity of the mechanisms underlying the fixation and installation of microorganisms on a given surface, or substrate, is such that it is often impossible to predict which community will develop. The nature of the substrates, the physico-chemical environment, the surface roughness, seasonal fluctuations and various anthropogenic forcings all determine the interactions and make each biofilm unique.However, this uniqueness is only apparent. Whatever the complexity of the biofilm considered, its general structure will be invariable and will contain a certain number of elements of similarity with, in foreground, the secretion of extracellular polymers. These secretions support a number important ecosystem functions and services that are common to all microbial communities. My research aims to answer fundamental questions about the determinism of the fixation of microorganisms, their development and their roles in the functioning of ecosystems.This document summarises my research on microbial biofilms, mats and aggregates and attempts to build a unifying vision of these diverse communities
RÎle des communautés microbiennes dans les flux de matiÚre des sédiments meubles intertidaux
It becomes increasingly recognized that the coastal zone contributes significantly to the global carbon cycle. The interest for this system is relatively recent, although its role is potentially important at the global scale. The present work aimed to study the role of benthic microbial communities (microphytobenthos and heterotrophic bacteria) on the functioning of intertidal soft sediments. Benthic metabolism was measured during low tide at two contrasted sampling sites (a small intertidal estuary characterized by a strong environmental gradient and an exposed sandy beach). The gross primary production (GPP) and benthic community respiration (BCR) were estimated via in situ CO2 fluxes measurements at the air-sediment interface within a benthic chamber. Bacterial carbon production (BP) was measured through incorporation of radiolabeled nucleotide ([methyl-3H]thymidine) into bacterial cells. The benthic food web was studied by a dual stable isotopes analysis. Microbes contribute significantly to the production and respiration in intertidal sediments. In the Roscoff Aber Bay, regarding all the benthic compartments, the production of microalgae and bacterial communities represents respectively up to 88 and 81 % of the total annual primary and secondary productions. Micro-organisms thus play a key role in the benthic food webs. This role varies along the productivity gradient. The influence of the bacterial compartment decrease with increasing sediment organic matter content. It is thus supposed that the influence of the bacterial compartment in the benthic food web is primarily driven by the nutriment availability.Selon certaines estimations, le milieu cĂŽtier contribuerait de maniĂšre importante au cycle global du carbone. Cependant, malgrĂ© son rĂŽle potentiellement important, l'intĂ©rĂȘt pour ce milieu est relativement rĂ©cent. Le but de ce travail est d'Ă©tudier le rĂŽle des communautĂ©s microbiennes (microphytobenthos et bactĂ©ries hĂ©tĂ©rotrophes) dans le fonctionnement des sĂ©diments meubles intertidaux. Le mĂ©tabolisme benthique a donc Ă©tĂ© mesurĂ© Ă marĂ©e basse sur deux sites contrastĂ©s (une petite baie intertidale soumise Ă un gradient environnemental et une plage exposĂ©e aux vagues). La production primaire brute (PPB) et la respiration de la communautĂ© benthique (RCB) ont Ă©tĂ© mesurĂ©es in situ Ă l'interface air-sĂ©diment Ă l'aide d'une chambre benthique (mesure de la concentration en CO2). La production bactĂ©rienne a Ă©tĂ© mesurĂ©e par traçage d'un marqueur radioactif ([methyl-3H]thymidine). Le rĂ©seau trophiuqe benthique a Ă©tĂ© Ă©tudiĂ© par traçage isotopique du carbone et de l'azote (ÎŽ13C et ÎŽ15N). Les micro-organismes contribuent majoritairement Ă la production et Ă la respiration des sĂ©diments intertidaux. Dans l'Aber de Roscoff, la production des microalgues et des bactĂ©ries reprĂ©sente respectivement jusqu'Ă 88 et 81 % de la production primaire et de la production secondaire totale annuelle. Les micro-organismes jouent donc un rĂŽle prĂ©pondĂ©rant dans les rĂ©seaux trophiques benthiques. Ce rĂŽle varie en fonction du gradient sĂ©dimentaire. L'influence du compartiment bactĂ©rien sur la production globale du systĂšme diminue avec l'envasement. Il est supposĂ© que le rĂŽle des bactĂ©ries dans les rĂ©seaux trophiques benthiques est influencĂ© par la disponibilitĂ© des nutriments
Does seasonal proliferation of Enteromorpha sp. affect the annual benthic metabolism of a small macrotidal estuary? (Roscoff Aber Bay, France)
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Environmental heterogeneity drives phytoplankton community assembly patterns in a tropical riverine system
A recommendation â based on reviews by Eric Goberville and Dominique Lamy â of the article: Graco-Roza C, Segura AM, Kruk C, Domingos P, Soininen J, Marinho MM (2021) Clumpy coexistence in phytoplankton: The role of functional similarity in community assembly. bioRxiv, 869966, ver. 6 peer-reviewed and recommended by Peer community in Ecology. https://doi.org/10.1101/86996
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