[en] The Southern Ocean is hosting a huge biomass of pelagic resources (pelagic fish and crustaceans), yet essentially unexploited. Biomass and species diversity of such resources are remarkably high in the waters surroundings the French Southern and Antarctic Territories (DOM-TOM). These resources account for a substantial part of the energy transfer from secondary production to higher trophic levels and make the bulk of the food for very large populations of predators (birds and pinnipeds). While the consequences of ENSO on tropical ecosystems are well documented, little is known on the biological response of the Southern Ocean marine food webs, and even less is known on the response of the Southern Ocean ecosystems to long-term climate variability. These difficulties can be partly explained by logistical difficulties for in situ sampling of such a vast and remote ocean. The main objective of this multidisciplinary research project was to evaluate the biological impact of short-term and long-term climate variability on at-sea distribution and abundance of pelagic resources of the Southern Ocean, based on a new approach using their main predators (seabirds, pinnipeds and cetaceans) as oceanographic auxiliaries. Predators integrate spatially and temporally the trophic and physical changes that occur at several trophic levels in the ocean and are very sensitive to environmental variability. The main study site was the Southern Indian Ocean, including the French Southern and Antarctic Territories (TAAF, DOM-TOM) Three research axes have been developed: 1) A retrospective analysis of time-series of marine predators spatial distribution. Time-series were made of i) 15 years of tracking data of predators foraging trips and ii) long term catching data from the International Whaling Commission (IWC). 2) A simulation of at sea distribution and abundance of marine resources (second trophic level). 3) A comparison of predators time-series as bio-indicators versus climatologies so as to estimate how changes in bio-indicators can be related to decadal changes of the ocean-atmosphere system. A fourth axis is still under development, involving prediction of the impact of climate change based on integrative modelling operating at several levels of ocean and climate forcing. Data from predators as bio-indicators were obtained by means of detailed telemetric studies of their oceanic foraging trips. Analysis of the seasonal and inter-annual datasets have provided estimations of the spatial distribution of pelagic fish resources (myctophids) at different scales and estimations of the myctophids relative abundance. Such information were inferred from the predators 'Catch per unit effort'. Analysis of primary production were based on weekly SeaWifs data extracted for the global Southern Ocean. Fish prey distributions were obtained using LOCEAN (ex-LODyC) 'forage' models of trophic transfer. Secondary production indices were developed by modelling the transformation and transport of the secondary production by surface currents fields. Indices of secondary production were parameterized following the first life stages of Antarctic Krill Euphausia superba. Climate variability in the study ocean regions has been inferred from spatial remote sensing and in situ hydrological data. The surface circulation (integrated over the depth of the euphotic layer) was based on Topex-Poseidon sea surface heights for the geo-strophic component and wind data for the Ekman component (ERS and Quicksat data). At some locations a correlation coefficient was used to measure associations between secondary production indices and the observed parameters. To determine the spatial scales of these associations, co-variograms between secondary production indices and each of the observed distribution were calculated. The typical spatial scales of the associations were determined from the theoretical variograms. (authors)

[en] Global environmental and climate conditions fluctuate on all kind of spatio-temporal scales. Some fluctuations or change/trends are not only anthropogenic, but have different regional and national signatures. While the frequency of extreme events on smaller scales is changing, the public sector and general opinion become more and more aware and concerned of local impacts from global environmental and climate changes. Indeed, negative effects and feedbacks, might occur on ecosystems, natural resources, buildings and grounds, superstructures, economies, food security, public health. This is how, during 1999, a concerted French initiative led to the research program 'Management and Impacts of Climate Change' (GICC). GICC is essentially managed by the Ministry of Ecology and Sustainable Development in close collaboration with the Inter-Ministerial Mission on Greenhouse Effect (MIES). GICC started in 1999. Its first phase (1999-2006) included four calls for proposal (1999, 2000, 2001, and 2002). In parallel and in 2003-2004, the MIES has been developing the so-called 'Climate Plan' based upon three principles : Insure that France follows agreements from the 'Kyoto Protocol'; Participate in ways and means leading to reduction of greenhouse gases by 75% in 2050; Allow for reduction of pollution from transportation means. Input from GICC Phase One final reports are contributing to 'Climate Plan'. The eight themes proposed by GICC-1 (1999-2002) are as follows: Theme 1: Evolution scenarios of the average and extreme features of the 21. Century climate; Theme 2: Interactions between climate, economy and society; related timescales; Theme 3: Role of carbon forest uptake and agricultural practices on climate policies; Theme 4: Links between national and international activities; Theme 5: Towards new inventories of GHG and aerosols (direct and indirect) emissions; Theme 6: Impacts on terrestrial biosphere; Theme 7: Impacts on hydro-systems; Theme 8: Impacts on public health. A symposium presenting the available results of the GICC first phase has taken place in MEDD, Paris, November 23-24, 2004. A final presentation workshop of the first phase took place in Paris, on May 11-12, 2006. This document is the proceedings of this scientific restitution seminar. It is organized in 9 sessions which follow the 8 themes listed above plus a round table for the status and perspectives of the GICC program. (J.S.)