Located in Northwestern France, the Bay of Brest constitutes a coastal macrotidal and semi-enclosed ecosystem (total area of 180 km2, maximum tidal amplitude of 8 m, average depth of 8 m) influenced by both freshwater inputs from rivers (to its east-side) and fast mixing exchanges with the Atlantic Ocean through a narrow (1.8 km of wide) and deep (40 m) channel (to its west-side). The average flushing time of the system is around 25 days. The shallowness of the bay and the water mixing induced by tidal currents prevent the ecosystem from vertical stratification and nutrient accumulation and therefore limit eutrophication. This environment is still very rich and shelters numerous species, macrobenthic communities and remarkable habitats (for instance: maerl beds, scallops and brittlestars sandy-shelly muds, flat oysters beds associated with black scallops, slipper limpet mixed sediments, zostera beds, intertidal pacific oyster population...).
Nevertheless, this ecosystem is also under the pressure of human activities: the north of the system shelters a population of 400 000 inhabitants whereas the south is more influenced by intensive agricultural activities. Marine resources are also intensively exploited by professional fishing, shellfish aquaculture and recreational activities (diving, fishing and picking).
One of the most productive area within the bay of Brest is the Daoulas bay – a very shallow embayment (max depth 8 m) - that receives the freshwater inputs of « The mignonne » river. This small bay harbours various aquaculture and fishing activities and also a protected marine area managed by Natura 2000. To better understand physical and biological processes within this bay and their evolution under the context of global change, an observation station has been set up since 2006. At the beginning, only water temperature was measured with the help of automatic probes. Nowadays, this observatory system includes a real time monitoring of the following environmental parameters: temperature, salinity, in vivo fluorescence (chlorophyll a), oxygen concentration, pH and turbidity.
Data are acquired with probes fixed on metallic structure at 50 cm over the sediment bottom on the foreshore in the intertidal zone. Since 2006, several type of probes were used and are listed in the data: EBI 85 from Global Water (http://www.globalw.com) ; DS5 Hydrolab from OTT (http://www.ott.com) ; SP2T, STPS or SMATCH from NKE (http://www.nke-instrumentation.fr). For each of them, temperature and salinity accuracies are also available. Time frequency of recording can differ from one probe to another but tends to be 15 minutes.
