ACOUSTICAL AND OPTICAL MEASUREMENTS ON ZOOPLANKTON WITHIN THE EQUATORIAL ATLANTIC CURRENT SYSTEM

摘要

Within a GLOBEC-France program named PICOLO, aiming to study the ecosystem's dynamics of the area 10-20°W / 0-5°N, where there is seasonally an important tuna fishery, the zooplankton survey appears as an essential component. During a cruise in August 97, zooplankton profiles where performed with both acoustical (TAPS-6, TRACOR Inc., San Diego, USA) and optical (UVP, Observatoire Oceanologique, Villefranche-sur-Mer, France) equipments. The TAPS, a multifrequency sensor, allows to estimate the size composition of the planktonic population, to calculate abundances and biovolumes per size class, over 0-200 m profiles. However it is the biovolume that is the more robust parameter The informations arising from the UVP are, over 60-1000 m profiles: abundance of particles > 150μm; suspended particles size spectrum; vertical distribution of the meso and macroplankton. During dark nights, observations can begin from the surface. Fourteen stations were made simultaneously with both equipments. Some comparisons are shown here, as well as the synthetic results provided by acoustics.