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
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
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
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
Onshore and offshore evidences for four abrupt “warming” episodes during MIS 6 at the westernmost tip of continental Europe: did they control the migrations of Neanderthals?
The total shell production typical of the Pupilla association in the onshore site of Nantois (Brittany, France) evidenced for the first time four brief, abrupt, warm and humid episodes during the Upper Saalian (MIS 6) loess deposition. These “warming” events were also found in the marine deposits of the Celtic Sea (MD03-2692 core). Comparison with the variations of the sea-level, show that the “warming” episodes were not only of regional interest but corresponded to global events ruled by precession and insolation cycles. Other comparisons with biomarker records (mollusсs, charcoal and rodents) of the Paris Basin (Villiers-Adam) and Jersey Island (La Cotte de Saint Brolade) confirm the existence of these warmer events. Tentative correlations with the discontinuous Neanderthal dwelling phases recorded in Brittany suggest that these populations were mainly (only?) present in Westernmost Europe during the warmer episodes.
(Quaternary International. vol. 534, n° 1040-6182, pp. 103-115, 01/12/2019)
CReAAH, UM, UR, UR2, CNRS, UFR HHAA, UN, MC, RAS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Nature-Based Solution along High-Energy Eroding Sandy Coasts: Preliminary Tests on the Reinstatement of Natural Dynamics in Reprofiled Coastal Dunes
This paper describes a large-scale experiment designed to examine if reinstating natural processes in the coastal dune systems of Southwest France can be a relevant nature-based adaptation in chronically eroding sectors and a nature-based solution against coastal hazards, by maintaining the coastal dune ecological corridor. An experiment started in late 2017 on a 4-km-long stretch of coast at Truc Vert, where experimental notches were excavated and intensively monitored in the incipient and established foredunes. Preliminary results indicate that most of the excavated notches did not develop into blowout. Only the larger elongated notches subsequently excavated in the established foredune in 2018 showed evidence of development, acting as an effective conduit for aeolian landward transport into the dunes. All notches were found to have a statistically significant impact on vegetation dynamics downwind, even those that did not develop. The area of bare sand landward and within the elongated notches notably increased implying a loss of vegetation cover during this first stage of development. Observations of a nearby coastal dune system that has been in free evolution over the last 40 years also indicate that, although the dune migrated inland by more than 100 m, it is now mostly made of bare sand. Further work is required to explore if and how dunes maintained as dynamic systems can become an efficient nature-based solution along this eroding coastline.
(Water. vol. 11, n° 2073-4441, pp. 2518, 28/11/2019)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, ONF, INCM, CNRS, IPR, UR, CNRS, LGCGM, UR, INSA Rennes, INSA, LTeN, EPUN, UN, CNRS, IPGP, INSU - CNRS, UPD7, UR, IPG Paris, CNRS