Influenza dei processi dinamici marini sulla distribuzione della produzione primaria fitoplanctonica nel Mar di Sardegna
Author(s)
Bonamano, Simone
Date Issued
June 12, 2013
Type
Doctoral Thesis
Abstract
In this work the effect of physical processes (i.e. eddies, fronts and upwellings) on the biological
variables distribution, with particular attention to phytoplankton primary production, was
investigated in four different time periods between 2002 and 2004 in the Sardinian Sea. In order to
study the main mesoscale phenomena in the Western Mediterranean Sea, a multidisciplinary
approach based on satellite observations, in situ data and numerical simulations was used. In
particular MADT (Mediterranean Absolute Dynamic Topography) satellite data and salinity
distribution calculated by OPA-NEMO numerical model allowed to detect intense mesoscale
activities like the Algerian Eddies (AEs) and the North Balearic Front (NBF). The effects of AEs
and NBF on the phytoplankton biomass and primary production distribution were analysed in the
Sardinian Sea by in-situ data collected during four oceanographic cruises (MedGOOS4,
MedGOOS5, MedGOOS6 and MedGOOS7). During these cruises more than 150 stations has been
investigated and hydrological data has been acquired by a SBE911 plus CTD probe. Moreover biooptical
variables has been detected in some CTD stations through the double impulse fluorometer
Primprod 1.08 that measures chlorophyll-a fluorescence, photosynthetic efficiency and PAR. To
evaluate the biological response associated with mesoscale processes, the phytoplankton primary
production (PP) was calculated by the new version of PhytoVFP bio-optical model. It contains two
main changes compared to the previous version: (1) the surface and underwater radiation was
estimated integrating the PAR spectrum (400-700 nm) each 60 bandwidth and considering the
cloud cover; (2) the photosynthetic rate was calculated using Platt formulation. In order to test these
upgrades, surface and underwater radiation were calibrated with in-situ data, while phytoplankton
primary production were compared with PP obtained by Morel model. During MedGOOS cruises,
the comparison between vertical distributions of potential density and phytoplankton primary
production calculated by PhytoVFP model allowed to analyse how the AEs and NBF can modulate
the biological response in the Sardinian Sea.
Additional information
Dottorato di ricerca in Ecologia e gestione delle risorse biologiche
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