Bio-optical observation and modeling of marine biomass and primary production, for applications in the coastal environment
Author(s)
Nardello, Ilaria
Date Issued
March 7, 2008
Type
Doctoral Thesis
Abstract
Marine primary production (PP), i.e. the rate of carbon assimilated through
photoautotrophic processes, is a key factor in the regulation of the global carbon cycle,
with important potential feedback on climate. Phytoplankton represent 1% of the total
terrestrial biomass but contribute 40% of global PP, through photosynthesis. Coastal
environments are among the most productive areas of the planet. The development of
predictive models, as well as the refinement of monitoring techniques in coastal areas
are fundamental to address the issues of sustainability in a climatically/economically
changing world. This study aims at using bio-optical techniques, which allow a synoptic
view of larger portions of given marine ecological systems, to estimate biomass and
primary production in temperate costal waters. With the use of laboratory studies, in situ
observations, and remote sensing (MODIS-Aqua), we have developed/refined, and
applied/validated, certain bio-optical models, at the regional scale. The diatom Skeletonema
costatum was chosen as a reference organism to model the effects of photo-acclimation on
marine phytoplankton photosynthesis. We have implemented these effects in a semianalytical
model of primary production (Phyto-VFP), and applied it to a large 4-year dataset
of oceanographic campaigns (SYMPLEX 1-4, N/O Urania_CNR), in the case I waters of
the Channel of Sicily. The sub-regionalization of our datasets, on a trophic-level basis, has
allowed us to reliably describe the annual cycle of primary production in this Mediterranean
province. Synoptic estimates of biomass and primary production are even more suitably
addressed by the use of satellite images, in large demand by administration agencies in
recent years, as a tool to monitor water quality in coastal environments. In our study we
have used three years of bio-optical observations to regionalize the standard MODIS-A
algorithm for the Chesapeake Bay. We have developed a regional algorithm (OC3CB) with
improved performance with respect to global OC4v4 and OC3M. We also describe an
original approach to the use of MODIS-A observations of ocean color, with the
development of a new product for MODIS-A (Lw510), especially conceived for coastal
applications.
Additional information
Dottorato di ricerca in Ecologia e gestione delle risorse biologiche
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