Natural Variability and Anthropogenic Changes in Coastal Marine Biogeochemical Cycles

Station biologique de Roscoff - www.sb-roscoff.fr

An excellence center at the heart of a regional, national and European network

The Station Biologique de Roscoff (SBR - photo), located on the Breton coast of the English Channel (map), is a research and training center in marine biology and oceanography, jointly operated by CNRS and Université Paris VI. The SBR is staffed by 46 faculty members and 60 technicians and senior technicians. Its missions are:

	to promote research and academic education on the biology of marine organisms and ecosystems;
	to provide access to the ecological and biological resources of the site, for the benefit of both the national and transnational scientific community;
	to carry out a series of long-term observations of the physicochemical and biological parameters of the coastal environment next to Roscoff.

The SBR is also actively involved in technology transfer through research contracts with private companies. It has a long tradition of hosting visiting scientists and academic courses from a variety of national and European universities. It currently hosts 27 PhD fellows. The SBR belongs to a larger set of teaching and research institutions of European dimension (1,200 persons) dedicated to marine sciences in Western Brittany.

At the European level, SBR is one of the leaders in marine biology. It coordinates the network of excellence "Marine Genomics Europe". SBR has also been awarded a grant from Early Stage Research Training (EST), a programme set up by the European Commission for the training of young foreign researchers.

Roscoff's location on the North coast of Brittany

SBR and the study of global ocean's change

Human activities are highly concentrated in coastal zones, as well as more than 50% of marine biological production. Therefore, coastal zones represent privileged places to study anthropogenic alterations of natural biogeochemical cycles and food chains functioning. In order to distinguish between natural variability and man-induced changes, long-term time series of observations in key sectors of the ocean are needed.

For more than 50 years, SBR has been collecting sea water temperature and salinity data off Roscoff. A multiparameter time series was initiated in 1985. From 1996, it participates in the national French programme Service d'observation du milieu littoral (SOMLIT). Through systematical and nationally coordinated observations realized on 7 different sites, situated on the English Channel, Atlantic, and Mediterranean French coasts, the overall goal of SOMLIT is to gather a set of hydro-climatic, chemical and biological parameters common to all the sites involved, in order to allow a comparative study of long-term observation series.

SBR is also in charge of the survey of the long-term variability of macrobenthic communities in the bay of Morlaix. Initiated in 1977, just one year before the tanker Amoco Cadiz's wreck, this temporal survey has enabled to measure the impact of a heavy accidental disturbance of the environment by hydrocarbons. Since 1990, the benthic survey of the bay of Morlaix is supported by the Réseau national d'observation de la qualité du milieu marin (RNO) coordinated by IFREMER. This survey gives a reference for the evaluation of possible natural or man-induced alterations, and essential information for the understanding of the pluriannual variability of benthic species populations and communities in relation with possible climatic changes.

The parameters studied

Biolimiting dynamic elements
The ocean's capacity to export carbon and to reduce atmospheric CO2 is linked to the disponibility in surface layers of chemical elements essential to phytoplancton production (nitrogen, phosphorus, metals…). SBR studies the transfer of these elements in the food web and the conditions of their turn-over in the euphotic zone. These research paths are presently developed in three programmes: in the North-East Atlantic (POMME), on the North Bay of Biscay (PNEC), and in the Western Mediterranean Sea (DYNAPROC).

Deep ocean circulation
Two series of tracers (natural: silicate, nitrate…, and transient: CFCs, CCl4) are used to study oceanic circulation. CFCs are used to estimate the time scales of the intermediate and deep ocean's circulation. Studies have been developed in South and tropical Atlantic within the WOCE-CITHER program, in North-East Atlantic and in Western Mediterranean. The researches are now carried out in the North Atlantic where a hydrographic repeated line is sampled between Greenland and Portugal to study the interannual to decadal variability of the ocean's circulation (OVIDE programme).

Analysis of trace elements and molecules in marine waters
These researches take place in national and international programmes developed by CNRS, IFREMER, and IRD. They are presently devoted to:

	Developing techniques for the analysis and speciation of trace metals by polarographic techniques;
	Developing methods for analysing nitrogenous compounds and 15N tracer (by isotope ratio mass spectrometry);
	Developing techniques for the analysis of volatile halocarbonated compounds (by gaseous phase chromatography coupled with mass spectrometry); these compounds are produced by algae and can be transferred to the atmosphere where they can reduce the ozone layer.

For more information: pilorge@sb-roscoff.fr