Last Abundant Appearance Datum of Hemidiscus karstenii driven by climate change
(Marine Micropaleontology. vol. 157, n° 0377-8398, pp. 101861, 30/03/2020)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, AORI, UTokyo
The nature of deep overturning and reconfigurations of the silicon cycle across the last deglaciation
Changes in ocean circulation and the biological carbon pump have been implicated as the drivers behind the rise in atmospheric CO 2 across the last deglaciation; however, the processes involved remain uncertain. Previous records have hinted at a partitioning of deep ocean ventilation across the two major intervals of atmospheric CO 2 rise, but the consequences of differential ventilation on the Si cycle has not been explored. Here we present three new records of silicon isotopes in diatoms and sponges from the Southern Ocean that together show increased Si supply from deep mixing during the deglaciation with a maximum during the Younger Dryas (YD). We suggest Antarctic sea ice and Atlantic overturning conditions favoured abyssal ocean ventilation at the YD and marked an interval of Si cycle reorganisation. By regulating the strength of the biological pump, the glacial-interglacial shift in the Si cycle may present an important control on Pleistocene CO 2 concentrations.
(Nature Communications. vol. 11, n° 2041-1723, 24/03/2020)
CEN, CNRM, INSU - CNRS, CNRS, Comue de Toulouse, Fédération OSUG, UGA, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, LSCE, UVSQ, INSU - CNRS, CNRS, DRF (CEA), CEA, PALEOCEAN, LSCE, UVSQ, INSU - CNRS, CNRS, DRF (CEA), CEA, SUERC
Impact of model free parameters and sea-level rise uncertainties on 20-years shoreline hindcast: the case of Truc Vert beach (SW France)
Shoreline change is driven by various complex processes interacting at a large range of temporal and spatial scales, making shoreline reconstructions and predictions challenging and uncertain. Despite recent progress in addressing uncertainties related to the physics of sea-level rise, very little effort is made towards understanding and reducing the uncertainties related to wave-driven shoreline response. To fill this gap, 2 the uncertainties associated with the long-term modelling of shoreline change are analysed at a high-energy cross-shore transport dominated site. Using the state-of-the-art LX-Shore shoreline change model, we produce a probabilistic shoreline reconstruction, based on 3000 simulations over the past 20 years at Truc Vert beach, southwest France, whereby sea-level rise rate, depth of closure and three model free parameters are considered uncertain variables. We further address the relative impact of each source of uncertainty on the model results performing a Global Sensitivity Analysis. This analysis shows that the shoreline changes are mainly sensitive to the three parameters of the wave-driven model, but also that the sensitivity to each of these parameters is strongly modulated seasonally and interannually, in relation with wave energy variability, and depends on the time scale of interest. These results have strong implications on the model skill sensitivity to the calibration period as well as for the predictive skill of the model in a context of future climate change affecting wave climate and extremes.
(Earth Surface Processes and Landforms. vol. 45, n° 0197-9337, pp. 1895 - 1907, 15/03/2020)
BRGM, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Monorchis parvus and Gymnophallus choledochus: two trematode species infecting cockles as first and second intermediate host
Abstract The most deleterious stage of a trematode life cycle occurs in the first intermediate host where the parasite penetrates as a miracidium and asexually multiplicates in sporocysts or rediae. When infection advances, other organs can be occupied with severe effects on host individual health and population dynamics. Existing studies focused on these host/parasite systems are still scarce due to the usual low prevalence in ecosystems. Using cockles (Cerastoderma spp.) and two trematode species (Monorchis parvus and Gymnophallus choledochus) infecting these bivalves as first and second intermediate host, the present work aimed to (1) summarize the most relevant literature and (2) provide new information regarding this host/parasite system, taking advantage of a 21-year monthly database from Banc d'Arguin (France). This long-term monitoring showed that different trematode species display varying host size range preference (6–38 and 31–36 mm for M. parvus and G. choledochus, respectively). The occurrence of coinfection was lower than expected, raising some questions related to parasite interspecific competition. This review improved our understanding of the processes shaping the prevalence and distribution of parasitism. This study highlighted that beyond constant trematode assemblage monitoring, there is a need to identify the main predictors of rediae/sporocysts infection, such as the definitive host dynamics and miracidium infection processes, for future better management of host severe disease and mortality episodes.
(Parasitology, n° 0031-1820, pp. 1-16, 04/03/2020)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Impact of human activities on the spatio-seasonal dynamics of plankton diversity in drained marshes and consequences on eutrophication
(Water Research. vol. 170, n° 0043-1354, pp. 115287, 01/03/2020)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, LIENSs, INSU - CNRS, ULR, CNRS, UNIMA
Backwash sediment record of the 2009 South Pacific Tsunami and 1960 Great Chilean Earthquake Tsunami
Following recent tsunamis, most studies have focused on the onshore deposits, while the offshore backwash deposits, crucial for a better understanding of the hydrodynamic processes during such events and offering an opportunity for sedimentary archives of past tsunamis, have mostly been omitted. Here, we present a unique sedimentary record of the backwash from two historical tsunamis sampled in a sheltered bay in American Samoa, namely the 2009 South Pacific Tsunami and the 1960 Great Chilean Earthquake Tsunami. Although not always concomitant with a marked grain size change, backwash deposits are identified by terrestrial geochemical and mineralogical signatures, associated with basal soft sediment micro-deformations. These micro-deformations, including asymmetric flame structures, are described for the first time in historic shallow marine backwash deposits and lead us to propose an improved depositional mechanism for tsunami backflow based on hyperpycnal currents. Moreover, this study brings a potential new criterion to the proxy toolkit for identifying tsunami backwash deposits, namely the basal soft sediment micro-deformations. We suggest that further studies focus on these micro-deformations in order to test the representability of this criterion for tsunami backwash deposits. Sheltered shallow marine environments in areas repeatedly impacted by tsunamis have a higher potential for the reconstruction of paleo-tsunami catalogs and should be preferentially investigated for coastal risk assessment.
(Scientific Reports. vol. 10, n° 2045-2322, pp. 4149, 01/03/2020)
LIENSs, INSU - CNRS, ULR, CNRS, UNSW, EDYTEM, USMB [Université de Savoie] [Université de Chambéry], CNRS, Fédération OSUG, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, URI, ANSTO
Tectonism and volcanism enhanced by deglaciation events in southern Iceland
(Quaternary Research. vol. 94, n° 0033-5894, pp. 94-120, 01/03/2020)
IUEM, IRD, INSU - CNRS, UBO EPE, CNRS, LGO, UBS, IFREMER, UBO EPE, CNRS, iSTeP, INSU - CNRS, SU, CNRS, LGL-TPE, ENS de Lyon, UCBL, INSU - CNRS, UJM, CNRS, BRGM, LSCE, UVSQ, INSU - CNRS, CNRS, DRF (CEA), CEA, PALEOCEAN, LSCE, UVSQ, INSU - CNRS, CNRS, DRF (CEA), CEA, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Marine monitoring in Europe: is it adequate to address environmental threats and pressures?
Abstract. We provide a review of the environmental threats and gaps in monitoring programmes in European coastal waters based on previous studies, an online questionnaire, and an in-depth assessment of observation scales. Our findings underpin the JERICO-NEXT1 monitoring strategy for the development and integration of coastal observatories in Europe and support JERICO-RI2 in providing high-value physical, chemical, and biological datasets for addressing key challenges at a European level. This study highlights the need for improved monitoring of environmental threats in European coastal environments. Participants in the online questionnaire provided new insights into gaps between environmental threats and monitoring of impacts. In total, 36 national representatives, scientists, and monitoring authorities from 12 European countries (Finland, France, Germany, Greece, Ireland, Italy, Malta, Norway, Poland, Spain, Sweden, UK) completed the questionnaire, and 38 monitoring programmes were reported. The main policy drivers of monitoring were identified as the EU Water Framework Directive (WFD), the Marine Strategy Framework Directive (MSFD), Regional Seas Conventions (e.g. OSPAR), and local drivers. Although policy drivers change over time, their overall purposes remain similar. The most commonly identified threats to the marine environment were marine litter, shipping, contaminants, organic enrichment, and fishing. Regime change was identified as a pressure by 67 % of respondents. The main impacts of these pressures or threats were identified by the majority of respondents (> 70 %) to be habitat loss or destruction, underwater noise, and contamination, with 60 % identifying undesirable disturbance (e.g. oxygen depletion), changes in sediment and/or substrate composition, changes in community composition, harmful microorganisms, and invasive species as impacts. Most respondents considered current monitoring of threats to be partially adequate or not adequate. The majority of responses were related to the spatial and/or temporal scales at which monitoring takes place and inadequate monitoring of particular parameters. Suggestions for improved monitoring programmes included improved design, increased monitoring effort, and better linkages with research and new technologies. Improved monitoring programmes should be fit for purpose, underpin longer-term scientific objectives which cut across policy and other drivers, and consider cumulative effects of multiple pressures. JERICO-RI aims to fill some of the observation gaps in monitoring programmes through the development of new technologies. The science strategy for JERICO-RI will pave the way to a better integration of physical, chemical, and biological observations into an ecological process perspective.
(Ocean Science. vol. 16, n° 1812-0784, pp. 235-252, 19/02/2020)
CEFAS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Large scale patterns of trematode parasite communities infecting Cerastoderma edule along the Atlantic coast from Portugal to Morocco
In this study, spatial sampling was performed from north Portugal to south Morocco to analyse trematode communities of the widespread bivalve Cerastoderma edule, host of several trematode species. From the twelve trematode species found in this study, nine were present in multiple aquatic systems demonstrating high trematode dispersal ability, driven by the presence of all hosts. Multivariate analysis related to trematode communities in cockles clustered: 1) Portuguese aquatic systems influenced by cold waters, leading to low trematode abundance; 2) coastal systems characterized by dominance of trematode Parvatrema minutum and muddy sediments; 3) lagoons (or bays) with high oceanic influence and high trematode diversity. These findings suggested that, besides host species presence, temperature is an important trigger for parasite infection, with coastal upwelling operating as a shield against trematode infection in Portugal and masking latitudinal gradients. Results highlighted the possible consequences of thermal modification mediated by oceanographic global circulation change on cockle populations.
(Estuarine, Coastal and Shelf Science. vol. 233, n° 0272-7714, pp. 106546, 05/02/2020)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS