Summary In this communication we present the preliminary results of a 
Lagrangian survey carried out during last June along the Catalan current, 
from the Gulf of Lions to Barcelona. According to previous studies, at the 
end of spring a water mass of relatively low salinity, originated in the 
Rhone River plume, is spreading widely through the surface of the Gulf of 
Lions. Part of this water is captured and advected by the NW Mediterranean 
shelf-slope current along the shelf break off the Catalan coast. The first 
part of the ARO-2000 cruise was devoted to a Lagrangian survey of this 
water mass, along the track of 3 Argos drogues, adapted to follow the 
current at a depth around 10 m. They were initially placed at the shelf 
break of the Gulf of Lions within the low salinity surface waters above 
mentioned. They were left to follow these surface waters while being advected 
by the shelf-slope current along ca. 200 km, during 10 days. The area was 
covered by a series of 68 sampling stations distributed in 9 sections, from 
the coast to the end of the continental slope. Each section was planned to 
cross the path of the drifters in such a way to meet the actual position of 
the drifters. Accordingly 9 of the stations followed the evolution of the 
same surface water parcel. All along the shiptrack, TS analysis of surface 
water and ADCP measurements were obtained. A CTD cast and zoo- and 
ichtyoplankton trawls were performed at all stations. In all of the stations 
corresponding to the advected water an exhaustive sampling of water was done 
to cover: nutrient (organic and inorganic), chlorophyll, microbial plankton 
and their activity, and phytoplankton.