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, “Putting the Extended Evolutionary Synthesis to the Test”. 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 – such as duration and exposure sequence – 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

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 à toute épreuve ?

National audienceLa Terre s'est formée il y a 4,5 milliards d'années mais nous ne le savons que depuis la seconde partie du XXe siècle. Alors que nous recensions quelques milliers d'espèces au milieu du XVIIIe siècle, on en identifie aujourd'hui deux millions, et l'on estime que ce nombre ne représente que 20 % de la richesse totale encore à décrire ! Quant à l'humain, si l'on pensait que son histoire se résumait à une succession de deux ou trois espèces sur deux millions d'années, on découvre aujourd'hui que dix fois plus d'espèces d'hominines ont existé, sur sept millions d'années. Chaque découverte augmente le niveau de complexité de ce que l'on sait et élargit le périmètre de ce qu'il reste à connaître.La vitalité de la recherche bénéficie de multiples évolutions techniques, méthodologiques et conceptuelles. Si l'histoire naturelle favorise depuis toujours les approches interdisciplinaires, quelques-unes – comme la cosmochimie, l'archéozoologie ou encore la paléogénétique – ont connu un grand élan ces dernières décennies. Le perfectionnement des outils de mesure, de l'imagerie scientifique ou des instruments de séquençage génétique donne un nouveau souffle à des études engagées de longue date. Enfin, de nouvelles façons de faire et de penser émergent, comme en témoignent l'essor des sciences participatives et l'apparition de nouveaux concepts (holobionte, anthropocène, One Health, etc.).Voici un aperçu des foisonnants travaux menés au Muséum 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 société. Des premiers indices de vies aux biofilms des caniveaux urbains, les contributions ici réunies relatent d'étonnantes petites et grandes découvertes. Entre miscellanées et synthèse, cet ouvrage donne à voir la diversité d'un patrimoine qu'il nous incombe de découvrir et de défendre

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

Rôle des communautés microbiennes dans les flux de matière 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 côtier contribuerait de manière importante au cycle global du carbone. Cependant, malgré son rôle potentiellement important, l'intérêt pour ce milieu est relativement récent. Le but de ce travail est d'étudier le rôle des communautés microbiennes (microphytobenthos et bactéries hétérotrophes) dans le fonctionnement des sédiments meubles intertidaux. Le métabolisme benthique a donc été mesuré à marée basse sur deux sites contrastés (une petite baie intertidale soumise à un gradient environnemental et une plage exposée aux vagues). La production primaire brute (PPB) et la respiration de la communauté benthique (RCB) ont été mesurées in situ à l'interface air-sédiment à l'aide d'une chambre benthique (mesure de la concentration en CO2). La production bactérienne a été mesurée par traçage d'un marqueur radioactif ([methyl-3H]thymidine). Le réseau trophiuqe benthique a été étudié par traçage isotopique du carbone et de l'azote (δ13C et δ15N). Les micro-organismes contribuent majoritairement à la production et à la respiration des sédiments intertidaux. Dans l'Aber de Roscoff, la production des microalgues et des bactéries représente respectivement jusqu'à 88 et 81 % de la production primaire et de la production secondaire totale annuelle. Les micro-organismes jouent donc un rôle prépondérant dans les réseaux trophiques benthiques. Ce rôle varie en fonction du gradient sédimentaire. L'influence du compartiment bactérien sur la production globale du système diminue avec l'envasement. Il est supposé que le rôle des bactéries dans les réseaux trophiques benthiques est influencé par la disponibilité des nutriments

Does seasonal proliferation of Enteromorpha sp. affect the annual benthic metabolism of a small macrotidal estuary? (Roscoff Aber Bay, France)

International audienc

Environmental heterogeneity drives phytoplankton community assembly patterns in a tropical riverine system

A recommendation – based on reviews by Eric Goberville and Dominique Lamy – 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