CASOTTI, R. Stazione Zoologica, raffa@alpha.szn.it
Ribera d'Alcala', M. Stazione Zoologica, maurizio@alpha.szn.it
BRUNET, C. Station Marine-Université du Littoral, brunet@loalit.univ-littoral.fr

 
PHYTOPLANKTON DISTRIBUTION AND PHYSIOLOGY AS FUNCTION OF MESOSCALE VARIABILITY IN THE CHANNEL OF SICILY (MEDITERRANEAN SEA)
 
In the Channel of Sicily (Mediterranean Sea) high mesoscale variability is reflected in the different composition of phytoplankton assemblages as well as their fluorescence and absorption characteristics. In the summer of 1997, several transects crossed a filament, generated from the upweeling of cold water. Phytoplankton biomass in the whole area was dominated by algae belonging to the pico-fraction, and the DCM was always formed by Prochlorococcus plus picoeukaryotes belonging to Dinophytes, Prymnesiophytes and Chrysophytes. Prochloroccus was most abundant inside the filament, and it showed the highest red fluorescence per cell, suggesting that the upward transportation was faster than the photoacclimation velocity of these algae. Although, we cannot exclude that a different population developped in the filament. As a matter of fact, at some stations, deep Prochlorococcus showed a bimodal distribution of light scatter and red fluorescence, suggesting the presence of distinct co-occurring populations. Single-cell characteristics could in this case used as markers of physical structures and water masses characteristics. Changes in phytoplankton composition and physiology influence the optical properties of seawater as well as primary production rates and this must be taken into account when using remote-sensed data.
 
Day: Thursday, Feb. 4
Time: Poster
Location: Sweeney Center
 
Code: CS62TH0708S