The Dyfamed time-series station: a reference to coastal studies in the Mediterranean sea

In the Mediterranean, seasonal variations of the trophic environment (primary production, specific biomass, particulate export) are extremely large, in response to physical constraints, specifically seawater temperature induced by seasonal exposure to the Sun. Since 1991, systematic biogeochemical studies were conducted at the DYFAMED site (28 nautical miles off Nice) with monthly cruises and continuous observation from a permanent mooring, in the form of an Observation Scientific Service of the marine environment from INSU/CNRS. The time-series station is located in the central zone of the Ligurian Sea, and protected from lateral inputs by the presence of the liguro-provencal front, acting as a barrier to exchanges with the coastal zone. The anthropic inputs to the zone are only through the atmosphere. Then, the observed system is independent from anthropogenic coastal inputs and constitute a reference area for the study of the “natural” variability of the Mediterranean environment. Since the northwestern Mediterranean Sea is relatively homogeneous in term of atmospheric forcings, it can be considered that these “natural” variations of marine environment occur with a comparable intensity and rythmicity in the coastal and open sea areas. A coastal perturbation may then produces modifications of this background evolution. The data presented aim to characterize the seasonal variations at the and trophic observation site. Some results of studies undertaken since 1997 on the Nice-Calvi (Corsica) transect are also presented in order to explore the synchronism between the temporal succession of species from coast to open sea. With the aim to reach the scale of perturbation processes, it is clear that a continuous record of selected parameters is necessary