research thematic – Laboratoire LEMAR UMR 6539

Integrative host-microorganism-environment approaches

In a context of climate change, the emergence of diseases significantly modifies the dynamics of host and pathogenic populations, but also the networks of more complex interactions at different scales in the ecosystem

Marine ecosystems are made up of complex interaction networks integrating different levels of temporal and spatial scales. However, global changes can modify these networks by increasing the intensity and virulence of infectious diseases. It is now essential to have a detailed understanding of host-microorganism-environment systems, which requires integrative approaches including the study of all symbiotic organisms (viruses, prokaryotes or eukaryotes) and more broadly of host-associated microbiota, as well as the physiology of host or vector organisms (e.g. immune system and inflammation, metabolism and nutrition), all within a global environmental approach. This integrative approach, which is a growing strength within LEMAR, will focus on understanding these associations by calling on multiple skills (“omics”, genetics, epigenetics, cellular functional analyses), allowing us to integrate new concepts of evolutionary ecology and health (“One Health”) into our research, which will disrupt our paradigms on host-microorganism-environment systems.

05/10/2018/by sherve@univ-brest.fr

In a context of climate change, the emergence of diseases significantly modifies the dynamics of host and pathogenic populations, but also the networks of more complex interactions at different scales in the ecosystem

Adaptive physiological and behavioural responses of organisms to multiple environmental stresses

Panorama-thematic, research thematic

observation, experimentation and modelling

One of the great strengths of the PANORAMA team lies in the study of the physiological and behavioural responses of marine organisms to environmental constraints, whether of biotic or abiotic origin. The team strives to understand the effects of factors related to climate change (warming, acidification, hypoxia, nutritional constraints) and/or emerging pollutants on different species present mainly in coastal areas, in a monofactorial or multistress manner. In particular, it is developing approaches in ecotoxicology aimed at studying, on different models, the impact of micro- and nanoplastics, for which our laboratory is a precursor, or that of toxic microalgae, which also represents one of the laboratory’s strengths, or even that of diffuse pollution. We have exceptional structures and experimental and observation means that allow us to monitor the effect of these disturbances and contaminants, in large volumes and over the entire life cycle of the organisms: gametes, embryos, larvae, juveniles and adults. Thanks to this, we also understand the inter- and trans-generational effects of contaminants, pollutants, toxic microalgae and their toxins. Our experimental approaches are complemented by parallel studies in the natural environment where observational monitoring (e.g. monitoring of toxic microalgae blooms) and in situ experiments (e.g. caging experiments) are carried out. Our laboratory is very present in Brest, in the framework of sustained collaborations with CEDRE and ANSES, but also at the national level, with active participation in the GdR Aquatic Ecotoxicology, and the animation of the GdR PHYCOTOX and the GdR “Polymers and Oceans”. Our approach integrates all levels of biological organisation thanks to the new “omics” approaches in ecotoxicology, in association with cell biology, histology and eco-physiology measurements. We complete this coupling of observation and experimentation with modelling in conjunction with the “Coupling” Transverse Axis and the modellers of the DISCOVERY team.

05/10/2018/by sherve@univ-brest.fr

Our approaches in ecotoxicology consider the impact on marine organisms of emerging pollutants, toxic micro-algae, but also the effects of diffuse pollution and multi-stress

New insights into trophic ecology

Discovery-thematic, research thematic

Understanding how ecosystems function depends on our ability to identify the pathways by which energy and matter move through communities. This description is complicated in the marine environment by (1) the microscopic nature of the sources ingested by many organisms, (2) the spatial and temporal variability of the diet of organisms, (3) the high mobility of many species, which have the ability to find food in many different habitats, and (4) the highly opportunistic nature of many species from a dietary perspective. Understanding trophic relationships within ecosystems thus requires our ability to study these relationships empirically in the natural environment, to describe the forcing variables via experimentation, and to understand the consequences, from the organism to the ecosystem, via modelling approaches. In this context, LEMAR has undergone strong development over the past few years with the recruitment of researchers, teacher-researchers, engineers and technicians, and the development of analytical platforms giving it an unrivalled capacity in France in the field of isotope and lipid analysis applied to the marine environment, as well as in the field of bioenergetic and ecosystem modelling. These approaches are now used in all marine environments, coastal and offshore, polar, temperate and tropical, on numerous biological models and habitats, and will continue to develop over the next few years; they will provide new perspectives for understanding the functioning of marine ecosystems and organisms.

05/10/2018/by sherve@univ-brest.fr

Acoustic ecology

Discovery-thematic, research thematic

Passive and active acoustics each contribute to the development of an acoustic ecology through different but non intrusive and non destructive methodologies. At the scale of aquatic ecosystems, active acoustics (sounder, sonar) allows the description of the “biotic landscape”, at high spatial and temporal resolutions, providing the distribution and density of nekton, micronekton and zooplankton present between the surface and the sea bed; fronts such as the thermocline or oxycline, can also be detected. Trophic relationships or physical/biological interactions can thus be highlighted. However, clarifying these remains a complex subject. Furthermore, for the intermediate trophic levels, biomass estimates, which are essential for many research projects (trophic environment of predators, hot spots to be preserved, contribution of nycthemeral migrations to carbon flows, improvement of biogeochemical or ecosystem models), require the recognition of organisms (gelatinous, crustaceans, mesopelagic fish), which remains a real challenge. Passive acoustics listens to and studies sounds from anthropophony (boats, threshing, fishing, etc.), from geophony (rain, waves, etc.) and from biophony. In invertebrates, passive acoustics is used in a wide range of applications, including the detection and identification of cryptic or endangered species, the estimation of population density, the location of individuals, and the monitoring of activity rhythms and the reproduction period. In the near future, passive acoustics should be able to offer new tools for assessing the health of marine ecosystems by combining biology, ecology, signal processing and artificial intelligence.

05/10/2018/by sherve@univ-brest.fr

New methodologies for observing coastal marine environments are being developed.

Links between biogeochemical cycles of metals and living organisms

Chibido-thematic, research thematic

Improving our knowledge of the metal cycle in contrasting environments of the world ocean is absolutely necessary for a better understanding of the oceanic biogeochemical cycles of major elements (C, Si, N, S) and the biological carbon pump. LEMAR is internationally recognised in this field, in particular through our strong involvement in the GEOTRACES programme. We combine observations, field or laboratory experiments and modelling. Our originality lies in the combined study of the dissolved and particulate phases, as well as their speciation (redox and organic), in order to better understand the interactions between these two reservoirs, which are fundamental in the metal cycle and yet are still little studied. Our expertise also includes the study of interactions between the metal cycle and plankton, by linking metal speciation to the bioavailability of micronutrients for marine plankton (phytoplankton and bacteria). The integration of omics tools (functional genomics, transcriptomics, etc.) into this theme is currently essential to further investigate the link between biogeochemical cycles of metals and interactions with living organisms. These explorations will continue to be carried out, both during oceanographic missions and in laboratory studies, notably thanks to our numerous international collaborations and our involvement in the future international programme BioGeoSCAPES (‘Ocean metabolism and nutrient cycles on a changing planet’). The strong international momentum of the GEOTRACES programme and the forthcoming BioGeoSCAPES programme now allows us to build and meet the challenge of integrated microbial biogeochemistry projects that require international coordination with a multidisciplinary approach.

05/10/2018/by sherve@univ-brest.fr