The PACTE project is an interdisciplinary and multi-institutions (UBO,UBS, Ifremer, CNRS) project that aims at reconstructing the trajectory of the Bay of Brest socio-ecosystem in response to the changes in soil usages and occupation undergone by the watersheds over the last two centuries. The main objective is to build the first chrono-systemic timeline chart for the Bay of Brest (taken here as a representative pilot site for semi-enclosed bays) by the deployment of an integrative and interdisciplinary scientific strategy that will combine (i) Sedimentological, geochemical, paleo-ecological and paléo-genetical retro-observations from esturian sedimentary archives, (ii) Analysis of historical archives of the changes in watersheds land cover and usage (agriculture, industrial activities), marine activities (fisheries, aquaculture) and major climatic events (storms, extreme tempreatures, floods and droughts), (iii) the instrumental monitoring of the bay of Brest fluvial and coastal hydrosystems and (iv) the numercial modelling of the physico-biogeochemical trajectory of the studied estuaries along the land-sea continuum (waterflux, wtaer temp., nutrients concentration, ratios and fluxes, oxygenation, phytoplanktonic biomass, etc...) issued by the coupling of fluvial (RIVERSTRAHLER) and estuarine/marine (C-GEM, ECO-MARS3D) models.

The PACTE01 cruise is designed to meet the needs of the Sedimentary Retroobservation work packages (WP 2 and 3, coordinated respectively by J. Goslin/C. Lambert and R. Siano/J. Sutton) and Land-Sea Modelling (WP4, coordinated by M. Raimonet/Y-M Paulet) of the PACTE project. This involves acquiring data on estuary imaging and the architecture of estuarine sedimentary bodies during an initial PACTE01-1 cruise, and taking sediment core samples from previously identified sites during a second cruise, PACTE01-2.