Salvador Lluch, from CIBNOR (La Paz, Mexico) will be at the IUEM at the end of November, and will give a conference on monday, novembre 26th, at 10:30, in the amphitheatre A.
Title: Revisiting the Regime Problem (once again)
Revisiting the Regime Problem (once again)
Title: Sclerochronological approaches in Saint-Pierre & Miquelon: from sub-hourly to multidecadal environmental reconstructions
The panel will be composed of:
Thesis supervisors:
Summary :
Coastal ecosystems are exposed to global climate change leading to modifications of their structure and functioning. However, little is known about the variability of their physical properties before 1950, mainly because of the lack of long-term instrumental measurements. The hard parts of long-lived marine biota hold the potential to extend instrumentally derived observations, at different temporal and spatial resolutions, in order to enhance our understanding of past environmental processes.
This PhD dissertation takes place on Saint-Pierre & Miquelon (SPM), a small archipelago at the confluence of major oceanic currents marking the boundary between the North Atlantic Ocean subtropical and subpolar gyres. In addition to its global key position, the abrupt bathymetric change occurring in the North West of Miquelon Island generates the anti-cyclonic propagation of a tidal coastal trapped wave around this archipelago. This local phenomenon, leads during the stratified period to the largest (up to 11.5°C amplitude) daily (25.8 h) temperature oscillations ever observed-at any frequency-on a stratified mid latitude continental shelf.
This work is based on the analyses of local marine biota hard parts to gain insights about past environmental variability at these two scales. First, I have learned different sclerochronological methods through Spisula solidissima study. Global and multi-decadal time scales were reached using the longest lived bivalve known to date Arctica islandica, and Clathromorphum compactum a newly discovered long-lived coralline alga. The relationships observed at SPM between A. islandica and C. compactum sclerochronological records and different geographical scales environmental datasets yield details about past large-scale oceanographic variability and ecosystem dynamics. Local, high-frequency (25.8 h) temperature oscillations were tracked using sclerochronological information contained in Placopecten magellanicus a fast growing (ca. 500 µm / day) bivalve species.
This study points out the relevant position of this archipelago for studying multiple scale oceanographic variability, biological responses and ecosystem dynamics facing global changes.
Summary:
The performance of the MARS and CROCO models was evaluated on a 500m resolution model. This work is based on existing measurement networks in the bay of Seine (SMILE, D4/SCENES, SYNAPSES, tide gauges, SST SEVIRI.
“Hydrodynamic modelling in the Bay of the Seine: Intercomparison between the MARS and CROCO models”
Title: “Study of the climatic and environmental determinants involved in the variability of the reproduction and recruitment of three bivalves exploited in Brittany”
Summary: Current trends in global warming could lead to severe ecological consequences for marine species and communities in coastal areas. Using three marine bivalve species as models (C. gigas, O. edulis, and P. maximus), the objective of this thesis was to improve our knowledge of the potential effect of climate variability on coastal benthic organisms, particularly with respect to their reproduction and recruitment. Using a numerical modelling tool (DEB model) coupled with IPCC climate scenarios, we have highlighted new perspectives on the reproductive responses of C. gigas and P. maximus to global warming. With regard to C. gigas, we have shown that the increase in water temperature has allowed a greater number of spawnings in the Brest harbour since 1995.
In P. maximus, the model made it possible to explain the different reproduction strategies between two Breton ecosystems: the water temperature modulates the onset of egg laying in Saint-Brieuc Bay, whereas it is the phytoplankton concentration in the Brest harbour. In addition, we carried out a retrospective analysis of the breeding cycle and recruitment of O. edulis in another ecosystem in Brittany, Quiberon Bay. The use of a generalized linear model allowed us to show that NAO+ winter weather regimes explain part of the variability in flat oyster reproduction: the higher the occurrence of NAO+ days in winter, the earlier the appearance of milky and slate oysters in the year.
The BioTechAlg Joint Laboratory was inaugurated on Friday 26 October, at the European University Institute of the Sea, in the presence of Mr Matthieu Gallou, President of the University of Western Brittany.
This new Joint Laboratory, accredited by the French National Research Agency, is a premiere at the University of Western Brittany. It is the result of a partnership between the Laboratory of Environmental Marine Sciences and the microalgae producer company Greensea, with the support of the SATT Ouest Valorisation, and aims to identify new molecules derived from microalgae. These still unknown compounds are of major strategic interest to the cosmetics and food industry: in the long term, for example, they can replace chemical preservatives that pose many public health problems.
Copyright : Laboratoire LEMAR- 2018
