Influence de la variabilité climatique sur les communautés zooplanctoniques des zones côtières : importance des suivis à long terme
Les systèmes côtiers, parmi les plus importants écologiquement et économiquement, sont fortement menacés par l’influence combinée du réchauffement climatique et des forçages anthropiques directs. Pendant les deux dernières décennies, des changements concomitants dans l’environnement, le climat régional et les conditions hydro-climatiques à grande échelle ont été détectés. Ces changements affectent les compartiments biologiques, du phytoplancton aux consommateurs supérieurs, altérant la structure et le fonctionnement des écosystèmes. Les modifications de biodiversité peuvent s'opérer sur de longues périodes, ou résulter de l’accumulation des changements subtils pouvant entraîner des perturbations à l’échelle de l’écosystème. Un des défis actuels est l'identification d'une part d'outils numériques permettant de mesurer les changements de biodiversité et d'autre part les facteurs et mécanismes à l’origine de ces modifications. Dans ce contexte, l’objectif général de cette thèse est la caractérisation de l’influence de la variabilité climatique sur les communautés zooplanctoniques des zones côtières en liaison avec les facteurs environnementaux. L’application d'analyses multivariés sur des données issues de suivis environnementaux récurrents pour la période 2001-2014, a permis de caractériser les liens entre le forçage climatique à différentes échelles spatiales, la variabilité environnementale et une modification abrupte dans la communauté zooplanctonique du Bassin d’Arcachon au milieu des années 2000. Une approche comparative à l’échelle régionale à cette même échelle temporelle, associant variabilité des indices de biodiversité et analyses multivariées, a permis d’identifier des changements simultanés mais non convergents de la diversité zooplanctonique du Bassin d’Arcachon et de l’Estuaire de la Gironde au milieu des années 2000. L'approche prospective réalisée sur le littoral mexicain (Sud du Golfe de Californie) a amené à caractériser le contexte climatique, l’environnement pélagique et la communauté zooplanctonique pendant une période marquée par un événement ENSO intense. Les éléments de connaissance qui en sont issus permettront d'établir les bases du développement d’un suivi environnemental récurent en milieu littoral, dans cette zone prioritaire en termes de biodiversité.
(13/12/2019)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Coastal Change in Tropical Overseas and Temperate Metropolitan France Inferred from a National Monitoring Network: A Summary from the Current Special Issue
This paper provides an overview of the papers published in this Special Issue « Coastal Evolution under Climate Change along the Tropical Overseas and Temperate Metropolitan France » of Journal of Coastal Research. This special issue reflects the large diversity of mainland and tropical French coast and highlights the complex, site-and timescale-specific, combination of factors driving coastal evolution. Many contributions reveal a strong climate control on storm wave activity and, in turn, coastal response. In some contributions, the inherited geology and anthropogenic factors clearly appear affect coastal change. This special issue emphasises the need to monitor the coast combining different means to improve our understanding and predicting capacities of the natural variability of coastal response in a changing climate.
(Journal of Coastal Research, n° 0749-0208, 01/12/2019)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, LIENSs, INSU - CNRS, ULR, CNRS
Alongshore-Variable Beach and Dune Changes on the Timescales from Days (Storms) to Decades Along the Rip-dominated Beaches of the Gironde Coast, SW France
The high-energy meso-macrotidal 110-km long Gironde coast, SW France, is primary composed of quasi-straight sandy beaches bordered by high and wide coastal dunes. Beaches are intermediate double-barred and are essentially morphologically variable alongshore with ubiquitous rip channels incising both bars. These rip channels enforce a strong alongshore variability in the morphology of the dry beach and/or of the dune, morphological patterns referred to as megacusp embayments. In this study, we use 70-year diachronic shoreline data, 3.5-year semi-annual in situ shoreline surveys since 2014, combined with 12.5-year monthly to semi-monthly topographic surveys collected since 2005 at Truc Vert beach. Results show that 2 types of megacusp can be identified: (1) accretive megacusps on the upper beach, forming through a sequence of accretionary beach states following a storm event, are enforced by inner-bar rip channels with a spacing of O(100 m) and a typical lifetime of a few months and (2) erosive megacusps cutting the dune, forming during severe-storm driven erosive events, which are primarily enforced by the outer-bar morphology with a spacing of O(1000 m). These erosive megacusps do not migrate alongshore and can persist for years to decades. The outstanding winter of 2013/2014 drove the formation of erosive megacusps all along the coast, dramatically altered the coastal landscape and also impacted the behaviour and mean spacing of the accretive megacusps during the subsequent years. Overall, the study demonstrates the complex interplay between the nearshore morphology and the alongshore-variable changes of the foreshore/backshore from the timescales of days to decades, with accessional outstanding winters having the potential to deeply affect beach morphology and rhythmicity on the time scale of a few years, at least.
(Journal of Coastal Research. vol. 88, n° 0749-0208, pp. 157 - 171, 01/12/2019)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Change along the Tropical Overseas and Temperate Metropolitan France
This paper presents how major French science-oriented public institutions and Ministry of Higher Education, Research, and Innovation (MESRI) have developed and structured coastal observatories along metropolitan and oversea coastlines in order to better understand the metropolitan and oversea French coastal evolution on a wide range of temporal and spatial scales. Scientific results presented in this special Issue have been obtained in the framework of the resulting DYNALIT / ILICO observatory network.
(Journal of Coastal Research, n° 0749-0208, pp. 1 - 2, 01/12/2019)
LGO, UBS, IFREMER, UBO EPE, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Antarctic Sea Ice Proxies from Marine and Ice Core Archives Suitable for Reconstructing Sea Ice over the past 2000 Years
Dramatic changes in sea ice have been observed in both poles in recent decades. However, the observational period for sea ice is short, and the climate models tasked with predicting future change in sea ice struggle to capture the current Antarctic trends. Paleoclimate archives, from marine sedimentary records and coastal Antarctic ice cores, provide a means of understanding sea ice variability and its drivers over decadal to centennial timescales. In this study, we collate published records of Antarctic sea ice over the past 2000 years (2 ka). We evaluate the current proxies and explore the potential of combining marine and ice core records to produce multi-archive reconstructions. Despite identifying 92 sea ice reconstructions, the spatial and temporal resolution is only sufficient to reconstruct circum-Antarctic sea ice during the 20th century, not the full 2 ka. Our synthesis reveals a 90 year trend of increasing sea ice in the Ross Sea and declining sea ice in the Bellingshausen, comparable with observed trends since 1979. Reconstructions in the Weddell Sea, the Western Pacific and the Indian Ocean reveal small negative trends in sea ice during the 20th century (1900-1990), in contrast to the observed sea ice expansion in these regions since 1979.
(Geosciences. vol. 9, n° 1023-7429, pp. 506, 01/12/2019)
BAS, NERC, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, UniFI, AWI
Quantifying uncertainties of sandy shoreline change projections as sea level rises
Sandy shorelines are constantly evolving, threatening frequently human assets such as buildings or transport infrastructure. In these environments, sea-level rise will exacerbate coastal erosion to an amount which remains uncertain. Sandy shoreline change projections inherit the uncertainties of future mean sea-level changes, of vertical ground motions, and of other natural and anthropogenic processes affecting shoreline change variability and trends. Furthermore, the erosive impact of sea-level rise itself can be quantified using two fundamentally different models. Here, we show that this latter source of uncertainty, which has been little quantified so far, can account for 20 to 40% of the variance of shoreline projections by 2100 and beyond. This is demonstrated for four contrasting sandy beaches that are relatively unaffected by human interventions in southwestern France, where a variance-based global sensitivity analysis of shoreline projection uncertainties can be performed owing to previous observations of beach profile and shoreline changes. This means that sustained coastal observations and efforts to develop sea-level rise impact models are needed to understand and eventually reduce uncertainties of shoreline change projections, in order to ultimately support coastal land-use planning and adaptation.
(Scientific Reports. vol. 9, n° 2045-2322, 01/12/2019)
BRGM, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, LIENSs, INSU - CNRS, ULR, CNRS, CNRM, INSU - CNRS, CNRS, Comue de Toulouse
Global invasion genetics of two parasitic copepods infecting marine bivalves
Invasive species, and especially invasive parasites, represent excellent models to study ecological and evolutionary mechanisms in the wild. To understand these processes, it is crucial to obtain more knowledge on the native range, invasion routes and invasion history of invasive parasites. We investigated the consecutive invasions of two parasitic copepods (Mytilicola intestinalis and Mytilicola orientalis) by combining an extensive literature survey covering the reported putative native regions and the present-day invaded regions with a global phylogeography of both species. The population genetic analyses based on partial COI sequences revealed significant population differentiation for M. orientalis within the native region in Japan, while introduced populations in North America and Europe could not be distinguished from the native ones. Thus, M. orientalis’ invasion history resembles the genetic structure and recent spread of its principal host, the Pacific oyster, Crassostrea gigas, while M. intestinalis lacks population genetic structure and has an overall low genetic diversity. Therefore, the native origin of M. intestinalis remains unclear. With this study, we demonstrate that even highly related and biologically similar invasive species can differ in their invasion genetics. From this, we conclude that extrapolating invasion genetics dynamics from related invasive taxa may not always be possible.
(Scientific Reports. vol. 9, n° 2045-2322, pp. 12730, 01/12/2019)
AD2M, SU, CNRS, SBR, SU, CNRS, AWI, HU, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, IFREMER, IMBE, AU, AMU, CNRS
Consistently dated Atlantic sediment cores over the last 40 thousand years
Rapid changes in ocean circulation and climate have been observed in marine-sediment and ice cores over the last glacial period and deglaciation, highlighting the non-linear character of the climate system and underlining the possibility of rapid climate shifts in response to anthropogenic greenhouse gas forcing. To date, these rapid changes in climate and ocean circulation are still not fully explained. One obstacle hindering progress in our understanding of the interactions between past ocean circulation and climate changes is the difficulty of accurately dating marine cores. Here, we present a set of 92 marine sediment cores from the Atlantic Ocean for which we have established age-depth models that are consistent with the Greenland GICC05 ice core chronology, and computed the associated dating uncertainties, using a new deposition modeling technique. This is the first set of consistently dated marine sediment cores enabling paleoclimate scientists to evaluate leads/lags between circulation and climate changes over vast regions of the Atlantic Ocean. Moreover, this data set is of direct use in paleoclimate modeling studies.
(Scientific Data. vol. 6, n° 2052-4463, pp. 1-12, 01/12/2019)
PALEOCEAN, LSCE, UVSQ, INSU - CNRS, CNRS, DRF (CEA), CEA, LSCE, UVSQ, INSU - CNRS, CNRS, DRF (CEA), CEA, ETH Zürich, ETH Zürich, LMC14 - UMS 2572, CEA, IRSN, MCC, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, UFF, CEOAS, OSU, GFZ, IFREMER, LPG, UA, UN UFR ST, UN, INSU - CNRS, CNRS, WHOI, WHOI, AWI, WHOI, VU, LDO, INSU - CNRS, UBO EPE, CNRS, UMD, GEOPS, UP11, CNRS, GM, IFREMER, CEREGE, IRD, AMU, CdF (institution), INSU - CNRS, CNRS, INRAE
Developmental and symptom profiles in early-onset psychosis
(Schizophrenia Research. vol. 93, n° 0920-9964, pp. 567-576, 01/12/2019)
AP-HP, SU, ISIR, SU, CNRS, NET, INSERM, GEIST, UNILIM, ISIR, UPMC, CNRS, NU, CHU de Poitiers [La Milétrie], LNFP, CNRS, METRICS, CHRU Lille, TCDV, INSERM, CHRU Lille, SCALab, CNRS, PIROS, ISIR, SU, CNRS, UPD7, LPPA, CdF (institution), CNRS, CEA, AP-HP, AFM-Téléthon, INSERM, SU, CNRS, IRD [France-Ouest], UPMC, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, UR
La colonisation des parcs d'énergies marines renouvelables facilite-t-elle l'introduction et la propagation d'espèces non indigènes ?
(Bulletin COME3T, n° 2743-6896, pp. 12, 01/12/2019)
FEM, LOG, INSU - CNRS, ULCO, CNRS, IRD [Ile-de-France], ULCO, LBCM, UBS, UBO EPE, IUEM, IRD, INSU - CNRS, UBO EPE, CNRS, CNRS, IUEM, IRD, INSU - CNRS, UBO EPE, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, MMS, UM, UN UFR ST, UN, UFR SPB, UN, BIOSSE, UCO, LEMAR, IRD, IFREMER, UBO EPE, CNRS, PatriNat, MNHN, CNRS, AFB