Do the levels of industrial pollutants influence the distribution and abundance of dinoflagellate cysts in the recently-deposited sediment of a Mediterranean coastal ecosystem?

We studied the relationships between sediment industrial pollutants concentrations, sediment characteristics and the dinoflagellate cyst abundance within a coastal lagoon by investigating a total of 55 sampling stations within the Bizerte lagoon, a highly anthropized Mediterranean ecosystem. The sediment of Bizerte lagoon is char- acterized by a high dinocyst abundance, reaching a maximum value of 2742 cysts·g−1 of dry sediment. The investigated cyst diversity was characterized by the presence of 22 dominant dinocyst morphotypes belonging to 11 genera. Two dinoflagellate species dominated the assemblage: Alexandrium pseudogonyaulax and Protoperidinium claudicans, representing 29 to 89% and 5 to 38% of the total cyst abundance, respectively, depending on the station. Seven morphotypes belonging to potentially toxic species were detected, including Alexandrium minutum, A. pseudogonyaulax, Alexandrium catenella/tamarense species complex, Lingulodinium polyedrum, Gonyaulax cf. spinifera complex, Prorocentrum micans and Protoceratium reticulatum. Pearson correlation values showed a positive correlation (α = 0.05) between cyst abundance and both water content and fine silt sediment content. Clustering revealed that the highest abundance of cysts corresponds to stations presenting the higher amounts of heavy metals. The simultaneous autoregressive model (SAM) highlighted a significant correlation (α = 0.05) between cyst accumulation and two main factors: sediment water content and sediment content for several heavy metals, including Hg, Cd, Cu, Ni and Cr. These results suggest that the degree of heavy metal pollution could influence cyst accumulation patterns.peer-reviewe

Impact of contaminated-sediment resuspension on phytoplankton in the Biguglia lagoon (Corsica, Mediterranean Sea)

In shallow human-impacted systems, sediment resuspension events can result in pulsed exposures of pelagic organisms to multiple contaminants. Here, we examined the impact of the resuspension of contaminated sediment on phytoplankton in the Biguglia lagoon (Corsica, Mediterranean Sea), by conducting an in situ microcosm experiment over a 96-hour period. Natural phytoplankton was exposed to elutriates prepared from a contaminated sediment resuspension simulating process, and its functional and structural responses were compared with those of non-exposed phytoplankton. The elutriates displayed moderate multiple contamination by trace metals and PAHs. Our results show that elutriate exposure induced both functional and structural phytoplankton changes. Elutriates strongly stimulated phytoplankton growth after 24 h of exposure. They also enhanced phytoplankton photosynthetic performance during the first hours of exposure (up to 48 h), before reducing it towards the end of the experiment. Elutriates were also found to slightly stimulate Bacillariophyceae, and conversely to slightly inhibit Dinophyceae in the short term. Additionally, they stimulated phycocyanin-rich picocyanobacteria in the short term (8-48 h) before inhibiting it in the longer term (72-96 h), and to inhibit eukaryotic nanophytoplankton at short term (8-48 h) before stimulating it in the longer term (72-96 h). Sediment resuspension is thus likely to have a significant effect on the global dynamics of phytoplankton in contaminated coastal environments

L’histoire de l’art entre idéologie et muséologie : Paul Vitry et son Michel Colombe (1901)

Lafabrie Michèle. L’histoire de l’art entre idéologie et muséologie : Paul Vitry et son Michel Colombe (1901). In: Michel Colombe et son temps. Actes du 124e Congrès national des sociétés historiques et scientifiques, « Milieu littoral et estuaires », Nantes, 1999. Paris : Editions du CTHS, 2001. pp. 127-146. (Actes du Congrès national des sociétés savantes. Section d'archéologie et d'histoire de l'art, 124

Histoire et archéologie au XXIème siècle, au croisement des sources

Le cas du trésor de Boscoreale Le document qu'il m'est donné d'étudier est composé de quatre photos représentant un bol de métal (un skyphos) finement travaillé, baptisé Le triomphe de Tibère, issu d'un trésor fameux dit de Boscoreale. L'objet est actuellement conservé à Paris, au musée du Louvre ((Exposée au Louvre depuis 1991, la coupe baptisée « Le triomphe de Tibère » fait partie d'une donation effectuée en 1986 par les héritiers du Baron Edmond James de Rothschild (1845-1934) rejoignant ..

Concentrations en éléments traces dans la magnoliophyte Posidonia oceanica

International audienc

Resilience and stability of Cymodocea nodosa seagrass meadows over the last four decades in a Mediterranean lagoon

Understanding what controls the capacity of a coastal lagoon ecosystem to recover following climatic and anthropogenic perturbations and how these perturbations can alter this capacity is critical to efficient environmental management. The goal of this study was to examine the resilience and stability of Cymodocea nodosa-dominated seagrass meadows in Urbino lagoon (Corsica, Mediterranean Sea) by characterizing the spatio-temporal dynamics of seagrass meadows over a 40-year period and comparing (anthropogenic and climatic) environmental fluctuations. The spatio-temporal evolution of seagrass meadows was investigated using previous maps (1973, 1979, 1990, 1994, 1996, 1999) and a 2011 map realized by aerial photography–remote sensing combined with GIS technology. Environmental fluctuation was investigated via physical-chemical parameters (rainfall, water temperature, salinity, turbidity, dissolved oxygen) and human-impact changes (aquaculture, artificial channel). The results showed a severe decline (estimated at -49%) in seagrass meadows between 1973 and 1994 followed by a period of strong recovery (estimated to +42%) between 1994 and 2011. Increased turbidity, induced either by rainfall events, dredging or phytoplankton growth, emerged as the most important driver of the spatio-temporal evolution of Cymodocea nodosa-dominated meadows in Urbino lagoon over the last four decades. Climate events associated to increased turbidity and reduced salinity and temperature could heavily impact seagrass dynamics. This study shows that Urbino lagoon, a system relatively untouched by human impact, shelters seagrass meadows that exhibit high resilience and stability

CNES Miniaturization Policy: An Answer to Nanosatellites Challenges

The reduction of mass and size with improvement of the performance of a device is a permanent challenge for the space industry. The French National Space Agency has funded hundreds of R&D activities in the past, in all dedicated technical areas to facilitate these kind of technological evolution. Miniaturization efforts have, more recently, encountered a growing field of application, the one of Nanosatellites. For these applications, performance/cost trade-off is largely dominated by full cost, that is to say the cost including the entire satellite system development, from the initial idea to the end of life, including operations, data processing and its distribution. The carried out trade-offs are therefore based on a different constraints environment, in which the risk variable is systematically re-evaluated considering the cost/performance couple; the methods, the development process and the planning of delivery being directly impacted by this challenge. In this logic, and while continuing its efforts to miniaturize and improve performance for conventional markets (Earth observation, science, telecommunications, ...), CNES has adapted its working environment around the Nanosats domain to accelerate the development of adapted solutions. This adaptation being made both in terms of new development processes and of use of new COTS technology for equipment themselves. Moreover, projects in New Space are changing the historical relationship between CNES and its industrial partners and are encouraging a transition from a client/provider approach to a more co-partners approach. The objective of success for both parties implies active collaboration. Together, CNES and industrials manage to anticipate difficulties and accelerate project schedule. The article presents the state of the current activities around the Nanosat environment by specifying the origin of these activities and the trends that are pursued for the future