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UMR 6143 "Morphodynamique Continentale et Côtière"
Le laboratoire Morphodynamique Continentale et Côtière (M2C) est une Unité Mixte de Recherche (UMR 6143) créée en 1996. Il est rattaché au CNRS (INSU en principal et INEE en secondaire), à l’Université de Caen Normandie (UNICAEN) et à l’Université de Rouen Normandie (URN).
Les recherches du laboratoire M2C s’intéressent à la caractérisation et à la modélisation de la dynamique des processus naturels et des différents compartiments, le long du continuum TERRE-MER, à différentes échelles de temps et d’espace. Les recherches s’organisent en 3 thèmes :
Les recherches du laboratoire M2C s’intéressent à la caractérisation et à la modélisation de la dynamique des processus naturels et des différents compartiments, le long du continuum TERRE-MER, à différentes échelles de temps et d’espace. Les recherches s’organisent en 3 thèmes :
- Bassins versants
- Estuaire
- Côtier
Ces recherches sont réalisées avec une approche interdisciplinaire intégrant des chercheurs spécialisés en mécanique, géosciences, océanographie et hydrologie, microbiologie et biologie des organismes.
En raison de la réponse qu’elles constituent aux attentes des gestionnaires, collectivités et industriels, les activités que nous menons en matière de valorisation s’inscrivent dans le cadre de différentes recherches appliquées.
Nos recherches couplent la mesure in situ grâce à de nombreux équipements dédiés (voir rubrique plateaux techniques), des approches expérimentales et de modélisations numériques.
Dépôts
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Evolution des dépôts
Dernières publications
With about 8000 marine benthic species, the amphipod crustaceans form one of the richest animal groups of the worldwide Ocean. They have colonized a wide range of soft-and hard-bottom natural and artificial habitats extending from the intertidal to hadal zones. Moreover, they show a broad size spectrum, with numerous giant species exceeding 20 cm in length and some species smaller than 2 mm. When biofouling artificial hard surfaces, some tube-building species can form very dense populations comprising up to 100,000 individuals per square meter. Amphipods are important prey for fish and mammals. Along with cephalopod juveniles, they are also included in the trophic diet of shorebirds that consume amphipods mostly during the low tide on tidal flats. They display diel migration, which reinforces the predation by demersal fish in the suprabenthic zone just above the sea bed, as well as by pelagic fish in the water column. Despite their importance in terms of biodiversity and trophic transfer, no general overview is available on the role of benthic amphipods in marine ecosystem food webs. Various methods, including laboratory and field experiments, as well as the analysis of stomach contents and DNA extraction, have been used to identify the prey/predator trophic links. Based on an extensive literature review, this study discusses the role of marine benthic amphipods as potential food for higher trophic levels in natural and artificial hard-bottom communities created via the construction of offshore wind farms.
Assessing long-term changes in groundwater is crucial for understanding the impacts of climate change on aquifers and for managing water resources.However, long-term groundwater level (GWL) records are often scarce, limiting the understanding of historical trends and variability. In this paper, we present a deep learning approach to reconstruct GWLs up to several decades back in time using recurrent-based neural networks with wavelet pre-processing and climate reanalysis data as inputs. GWLs are reconstructed using two different reanalysis datasets with distinct spatial resolutions (ERA5: 0.25 • x 0.25 • & ERA20C: 1 • x 1 •) and monthly time resolution, and the performance of the simulations were evaluated. New insights: Long term GWL timeseries are now available for northern France, corresponding to extended versions of observational timeseries back to early 20th century. All three types of piezometric behaviours could be reconstructed reliably and consistently capture the multidecadal variability even at coarser resolutions, which is crucial for understanding long-term hydroclimatic trends and cycles. GWLs'multidecadal variability was consistent with the Atlantic multidecadal oscillation. From a synthetic experiment involving a modified long-term observational time series, we highlighted the need for longer training datasets for some lowfrequency signals. Nevertheless, our study demonstrated the potential of using DL models together with reanalysis data to extend GWL observations and improve our understanding of groundwater variability and climate interactions.
Macrofaunal species inhabiting intertidal mudflats and performing intense bioturbation are considered as ecosystem engineers, since they profoundly influence their physical, chemical, and biological environments. Nowadays, to complete our knowledge on the effect of bioturbation processes on the surrounding environment, interdisciplinary approach is essential to unravel their complex intertwined effects on intertidal mudflats. In this study, the effects of bioturbators on sediment properties, biogeochemical variables, and microbial dynamics (microphytobenthos, bacteria and archaea) were investigated. To this end, manipulation experiments were carried out in an intertidal mudflat of the Seine Estuary (France) by revamped the abundance of the two dominant bioturbators, Scrobicularia plana and Hediste diversicolor, in winter and late summer. Results showed that the presence of H. diversicolor in winter had a significant effect, with a significant increase in bed level accretion and microbial nitrate reduction rates. In contrast, the presence of S. plana showed no significant impact on sediment properties, most likely due to a reduced bioturbating activity at low temperature. In summer, both ecosystem engineers strongly influenced their surrounding environment but with opposite effects. The intense reworking of the sediment surface by S. plana limited microbial growth and enhanced erosion processes. Conversely, the presence of H. diversicolor favoured sediment accretion and enhanced microbial growth. Overall, this interdisciplinary study confirms the importance of these two ecosystem engineers in temperate estuarine mudflats by highlighting their simultaneous and intertwined effects on the sedimentary, physicochemical, and biological features. This confirms the importance of actively considering ecosystem engineers when restoring the natural habitats of tidal flats to cope with the different vulnerability risks related to global warming (sandification of estuarine sediments, disappearance of productive mudflats, sea level rise, vulnerability to storms and erosion).
Abstract Background Major advances over the past decade in molecular ecology are providing access to soil fungal diversity in forest ecosystems worldwide, but the diverse functions and metabolic capabilities of this microbial community remain largely elusive. We conducted a field survey in montane old-growth broadleaved and conifer forests, to investigate the relationship between soil fungal diversity and functional genetic traits. To assess the extent to which variation in community composition was associated with dominant tree species (oak, spruce, and fir) and environmental variations in the old-growth forests in the Jade Dragon Snow Mountain in Yunnan Province, we applied rDNA metabarcoding. We also assessed fungal gene expression in soil using mRNA sequencing and specifically assessed the expression of genes related to organic matter decomposition and nutrient acquisition in ectomycorrhizal and saprotrophic fungi. Results Our taxonomic profiling revealed striking shifts in the composition of the saprotrophic and ectomycorrhizal guilds among the oak-, fir-, and spruce-dominated forests. The core fungal microbiome comprised only ~ 20% of the total OTUs across all soil samples, although the overlap between conifer-associated communities was substantial. In contrast, seasonality and soil layer explained only a small proportion of the variation in community structure. However, despite their highly variable taxonomic composition, fungal guilds exhibited remarkably similar functional traits for growth-related and core metabolic pathways across forest associations, suggesting ecological redundancy. However, we found that the expression profiles of genes related to polysaccharide and protein degradation and nutrient transport notably varied between and within the fungal guilds, suggesting niche adaptation. Conclusions Overall, our metatranscriptomic analyses revealed the functional potential of soil fungal communities in montane old-growth forests, including a suite of specialized genes and taxa involved in organic matter decomposition. By linking genes to ecological traits, this study provides insights into fungal adaptation strategies to biotic and environmental factors, and sheds light on the importance of understanding functional gene expression patterns in predicting ecosystem functioning.
This study addresses the scarcity of evidence on the relationship between benthic communities and coarse-grained sediments in the eastern English Channel. The region's geological history contributes to its predominantly coarse sediment composition. The study employs ternary plots to visualize benthic species' preferences and tolerance for sediment types, revealing their effectiveness. Redundancy Analyses (RDA) and species-level quantile regressions explore the influence of grain size on benthic species distribution. The results indicate a moderate impact of grain size, influenced by hydrodynamics. Estuaries, particularly the Seine Estuary, significantly shape benthic species distribution. Quantile regressions underscore the varied responses of benthic communities along the grain size gradient. The study underscores the importance of considering coarse sediments, offering insights into the complex relationship between benthic communities and sediment characteristics.
There is an increasing need in assessing ecological quality and integrity of estuaries and lagoons as transitional waters. This chapter shows the most recent efforts in assessing individual biological elements (from phytoplankton to fishes), together with the integrative tools developed in different geographical areas worldwide. However, reducing multifaceted information needed to describe complex ecosystems that are naturally stressed from multiple ecosystem elements to a single color or value is a substantial challenge to marine scientists, and requires the integration of different disciplines (chemists, engineers, biologists, ecologists, physicists, hydrologists, managers, etc.), to reach agreement on the final assignment of ecological status. Hence, in the future, emphasis needs to be directed at understanding the complexities of estuarine system functioning rather than simplifying, deconstructing and scaling down the system into smaller components. Indeed, the process of deconstructing an ecosystem for study and then reconstructing it to give a holistic and weighted assessment is by far the greatest challenge in areas where there are many activities, pressures and effects. Key Points • To manage human pressures and impacts on transitional environments, legislation worldwide require methods to assess their ecological status, and here we revise the different methods. • Although methods can address individual ecosystem components (e.g., phytoplankton, macroinvertebrates, fish), inte-grative methods to assess the status under an ecosystem approach are more common in recent times. • Due to the natural variability of estuaries, sometimes distentangling the effects from human pressures and natural stress, can be difficult. • We have reviewed methods to assess the status for phytoplankton, zooplankton, macroalgae, angiosperms, macro-invertebrates, and fish. • Traditional and new methods (e.g., molecular-based methods) are reviewed. • The integration of multiple components, in different geographical areas, is presented.
Crustal heat loss processes in contexts other than mid-ocean ridge flanks are still poorly understood and described in the literature. In this work, we present 54 new surface heat flow measurements recorded along the South Balearic margin and across the Hannibal High area, in the Western Mediterranean Sea, away from spreading centres. The South Balearic margin is a narrow continental margin expressed on the seabed topography by the steep Emile Baudot Escarpment while the Hannibal High area, further south, is a presumed volcanic oceanic crust zone. Recent heat flow studies pointed out the presence of strong local thermal anomalies, imprinted in regional deep basin heat flow increasing from the eastern to the western Algerian basins (70-90 to 100-130 mW/m<SUP>2</SUP>). The new data in this study confirm local anomalies around the Emile Baudot seamounts and allow the delineation of some low and high heat zones. We show that (1) a correlation exists between the heat flow variability and the sedimentary cover thickness, and (2) the most pronounced anomaly is a low heat flow zone (30 km wide) observed in the mid-slope South Formentera basin, close to the basaltic basement of the Los Martines volcano. The correlation of heat flow with sedimentary thickness, the lateral extent of the heat flow anomalies, the flux peak magnitudes, and the co-existence of both low and high anomalies suggest the presence of an active fluid circulation system. Based on the arrangement of the anomalies in relation to the basaltic basement seamounts, we consider a syphon-type circulation system in the Formentera basin. Reduced heat flow suggests a recharge zone close to the Los Martines seamount, while local high heat flow located close to a smaller seamount could be a potential zone of fluid discharge. Although different buoyancy-driven circulations could occur in the South Balearic margin, we believe that a syphon-type hydrothermal circulation along permeable basaltic mounds and sealed basement conduits, similar to the off-axis oceanic crust, is best developed in the young marginal basin of the South Balearic margin.
The Central English Channel troughs correspond to elongated incisions up to 250 m-deep, at several locations at the bottom of this sea corridor. Depending on their location, they are usually interpreted as part of the submerged quaternary paleovalley network or as resulting from megaflood events. Shedding light on these features, their age, and the processes underlying their development is key for understanding their significance in terms of event geology. The interpretation of a dense grid of high-resolution marine seismic data acquired in the Bay of Seine area reveals that the extensive Quaternary paleovalley and trough network commonly as associated to the "Channel River" system is actually subdivided into at least two superimposed and unrelated incised networks. The overlying network corresponds to fluvial incisions developing during low sea-level conditions of Pleistocene time and connects to the present day fluvial network. The underlying network corresponds to the troughs and appears as a complex, deeper, relatively discontinuous and isolated network. This older network shows unexpected local incision depth up to c.350-400 m-deep and complex sedimentary infill involving several sedimentary processes and environments from fluvial to tidal and shallow-marine. We discuss these observations and their implications for understanding the origin, age and development of the troughs all over the English Channel, from the Dangeard Troughs in the Dover Strait to the Hurd Deep at the western end. We also raise questions about the significance of these large incised features in terms of source-to-sink system of northwestern Europe.
Mots-Clés
Deposition
Geochemistry
Non-indigenous species
Benthos
Deep learning
Climate variability
Continuous wavelet transform
Marine renewable energy
Pleistocene
Géochimie
Géoradar
Bassin versant
Niger
Normandie
Bay of Seine
Morphodynamics
Carbonates
Anthropogenic impact
Organic matter
Erosion
Changement climatique
Tomography
Bacteria
Alderney Race
Hydraulic tomography
Modélisation
Chemometrics
Hydrogeophysics
Ecosystem functioning
Non-native species
Inversion
Holocene
Quaternary
Climate change
Normandy
Senegal
Physical modelling
Diversity
Sediments
Biodiversity
Sahel
Sediment core
Karst
Littoral
Sedimentology
Géomorphologie
GIS
Turbulence
Coast
Washover
Mediterranean
NAO
Hyperspectral imaging
Ecopath model
Offshore wind farms
Morphodynamique
Seine estuary
Dredged sediments
Stratigraphy
Introduced species
Sédiments
Sampling strategy
Antibiotic resistance
Granulométrie
Geomorphology
France
Sediment
Sédimentologie
Stratigraphie
Numerical modeling
Offshore wind farm
Inverse problem
Contamination
English Channel
Hydrodynamics
Neogene
Biomass
Estuary
Autocorrelation
Hydrology
Manche
SEDIMENT
Benthic macrofauna
Numerical modelling
Canal à houle
Coastal barrier
Modelling
Tectonics
Baie de Seine
Marine terrace
Sediment transport
Morocco
Climate
Escherichia coli
Mediterranean Sea
Watershed
Eastern English Channel
ACL
Ecological Network Analysis
English channel