Preprint volume - SIBM

Pre-print Volume – Posters
PLANKTON COMMITEE
G. SOCAL, F. BERNARDI AUBRY, D. BON 1 , S. CEOLDO 2 , A. DE LAZZARI,
C. FACCA 2 , S. FINOTTO, S. RIZZARDI 1 , A. SFRISO 2
Istituto di Scienze Marine CNR, Castello, 1364/A - 30122 Venezia, Italia.
giorgio.socal@ismar.cnr.it
1 Agenzia Regionale per la Prevenzione e la Protezione Ambientale, Padova, Italia.
2 Dept. Environmental Sciences, University Ca’ Foscari, Venezia, Italia.
SEASONAL AND SPATIAL DISTRIBUTION OF PHYTOPLANKTON
IN THE VENETO LAGOONS (CAORLE AND PO DELTA LAGOONS,
ITALY)
DISTRIBUZIONE STAGIONALE E SPAZIALE DEL FITOPLANCTON
NELLE LAGUNE VENETE (LAGUNE DI CAORLE E DEL DELTA DEL PO)
Abstract – Seawater samples were seasonally collected in 20 sites in the lagoons of the north western
Adriatic Sea in order to determine the phytoplankton abundance and taxonomic composition. Data showed
persistent blooming conditions (>10 7 cell l -1 ) from February 2008 to August 2008 in the Po Delta lagoons
and scarce abundance in the Caorle lagoons. Also community compositions appeared significantly different
in the two lagoon systems.
Key-words: phytoplankton, diatoms, lagoons, Italy.
Introduction – The north western coast of the Adriatic Sea is a complex system of
wetlands and lagoons. Due to its historical and socio-economical importance, most of
the studies have always focused on the Venice lagoon. Nevertheless, the Po Delta
lagoon system covers an area of 786 km 2 only in the Veneto area and represents an
important naturalistic oasis and an economical resource for more than 1500 employees
in the aquaculture and clam farming. The scientific literature dedicated to such area and
the Caorle lagoon is scarce and mainly focused on fish and birds. Even if
phytoplankton has a key environmental role and represents the food basis for mussels
and clams, no studies are available in such areas in terms of cell abundance and species
composition. The need to know the ecological status and, hence, the trophic conditions
of the considered areas, has recently gained relevance due to the regulations in the
Water Framework Directive 2000/60 (WFD). As a consequence, the local authorities
started to promote studies for all the water bodies, which ecological status should be at
least “good” by 2015. The present paper describes the first seasonal surveys of
phytoplankton distribution and taxonomic composition in the Caorle and Po delta
lagoons.
Materials and methods – In February, May, August, October and November 2008,
seawater samples were collected in 3 and 17 stations located in the Caorle and Po Delta
lagoons, respectively. For each station, hydrological parameters were measured, and
phytoplankton, nutrients and chlorophyll a samples were collected. The phytoplankton
analysis was performed with inverted light microscope according to the Utermöhl’s
method (1958). Nutrients and chlorophyll a were measured according to Strickland and
Parson (1972) and Holm-Hansen et al. (1965), respectively.
Results – On the basis of salinity values, two of the 3 sites in Caorle lagoon were
classified as oligohaline (