Projects

Marine biogeochemical cycles are the result of individual life histories of marine organisms. Therefore, a detailed understanding of the evolutionary forces driving biogeochemical fluxes needs both, observational and experimental analyses. The main aim of the working group of the GIS Europole Mer Chair, Axis 2, is to perform experimental analyses of key processes and evolutionary dynamics underlying important biogeochemical fluxes.

Axis 2 plans to document and investigate the climate variability of biogeochemical parameters (including oxygen and TEIs) in relation to physical and biogeochemical processes. Modelling studies will also move towards higher resolution to represent at least partially the mesoscale variability of the ocean (1/4° or more), in order to evaluate its impact on the transport and modification of water masses, as well as on the biological activity and on the structuring the ecosystem. We will make use of improved biogeochemical models that will rely on our in situ observations and process study experiments.

The European project EURO - BASIN is designed to advance our understanding on the variability, potential impacts, and feedbacks of global change and anthropogenic forcing on the structure, function and dynamics of the North Atlantic and associated shelf sea ecosystems as well as the key species influencing carbon sequestration and ecosystem functioning. In this framework, a PhD thesis has started deadling with simulating biogeochemical cycles and marine ecosystems. The exact aim of this work is to describe the processes driving the fate of organic matter, either towards higher trophic levels (resources), or towards the deep ocean (biological pump).

The objective of WP2 si to study coupling between physical oceanography, chemistry, TEIs, biology and modelling in order to better understand and quantify (i) the land-sea exchanges and their contribution to the global biogeochemical budgets, (ii) the biological pump and its perturbations at the ocean margins, (iii) the role of the ocean margins on the chemistry, biogeochemistry and global marine productivity of the ocean and (iv) the variability of marine resources at the eastern boundaries of ocean basins. To achieve these objectives, we need to significantly increase the acquisition of geochemical measurements together with physical flux measurements (water and mass transportation). The Bay of Biscay, the Benguela upwelling system and the Agulhas Bank are ideal laboratories to carry out such integrative studies. This will result in new proposals for multi-disciplinary oceanographic cruises, as well as process studies and modelling.

This project fitted within the study of climate change impact in the oceanic region located South of Africa, on the continental margin and in interaction with the offshore ocean. This study is a first quantitative attempt to implement coupled ocean-atmosphere modelling systems at a regional scale.

The "Ushant tidal front" is the dominant feature of the summer season hydrological structure of the Iroise Sea. It separates tidally mixed coastal waters from thermally stratified open Celtic Sea waters, and acts as a structuring element of the pelagic ecosystem in the area. The physical processes governing the dynamics of the Ushant front are the subject of the FroMVar project (supported since 2007 by IFREMER, INSU/LEFE/IDAO, UEB and DGA), which involves participants from many institutions in the Brest area (IFREMER, IUEM, SBR). The aim of the companion FroMBio project, supported by UEB and Europole Mer / Axis 2, is to study the influence of the front on the pelagic ecosystem. Analysis of the samples and data set collected during the 2009 FroMVar cruise is in progress.

Europole Mer supports an Ifremer project called "RICCO" (Regionalisation of the impact of climate change over the ocean"), by co-financing (with Ifremer) the a PhD project.

This PhD topic proposes, for the first time, to study the coupling between the biogeochemical cycles of Fe, Cu and Mn, and their interactions with oceanic phytoplankton. No results available to date.

The aim of WP3 is to constitute an aggregated set of satellite, in situ, model and biological growth records and determine (i) if we can detect meaningful events in large multi-source ocean observation databases, (ii) how consistent the various observations are, and (iii) if we can infer climate variations in satellite remote sensed surface climatologies and biological growth records over the past 15-20 years. The project will necessarily build on a transdisciplinary approach. Associated partners shall lead to conceptual and methodological progress in proxy science and complex system variability knowledge, data management and analysis, theoretical and numerical efforts.

ENSTA Bretagne and IUEM have worked together on Non-intrusive monitoring of scallop activity using passive acoustics. Scallop Pecten maximus (L.) is considered to be a natural archive recording daily environmental information. In this species, surprisingly the mechanisms linking shell growth and stria deposition in relation to environmental variations are poorly understood but are likely associated to the animal’s behaviour. We attempted to monitor scallop valves movements by passive acoustics that has the advantage of being totally non-intrusive, applicable over long terms, with a high sampling frequency and on a large number of individuals. By comparing acoustic recordings and movement captor data we showed that Pecten maximus valve movements produce a distinctive sound, characterised by a mean duration of 0.35s, a centre frequency of 25717 Hz, a frequency bandwidth of 23885 Hz and a wide-band received level of 94 dB r 1μPa2. In order to evaluate the feasibility of passive acoustic monitoring of these scallop sounds in natural environments, we estimated the detectability of a reference patch of scallops in different types of ambient noise levels (laboratory tank, two natural habitats, Wenz model).

The major tasks of this post-doc are to describe scallop reactions to environmental changes, assess growth response and finally extract environmental proxies from the shells of individuals of the great scallop Pecten maximus from the continental shelf (30-200m deep) of the Iroise Sea (47°30 to 48°30N and 4°20 to 8°30W) over the last 20 years.

This study deals with the analysis of ca. 700 graphs of scallos daily growth rate distributed over 12 sites along the European Atlantic facade [40°N in 65°N] and on shells from 1 to 5 years old. The growth is probably not linear and possibly controlled by a parameter. The temperature tested as the control parameter shows a histeresis pattern. Class 1 shells (first year of growth) begin to grow when surrounding temperature reaches 13,5°C and stop at 11,5 °C.