Preprint volume - SIBM

Pre-print Volume – Posters
Topic 3: INTEGRATED COASTAL ZONE MANAGEMENT
Results – Both the investigated sites highlighted a seasonal trend according to the O.
ovata occurrence. The species was found during October 2007 and from June to
September 2008 in the sampling station named “Giovinazzo-Riva del Sole”, the
abundance ranging from 6.400 to 1.945.600 cell/l in the in the bottom water samples.
In the station named “Torre a Mare-ex Motel Agip”, O. ovata was recorded during
October-November 2007 and from July to September 2008, the abundance ranging
from 320 to 2.496.000 cell/l. The peaks of abundance were recorded in the August-
September period in both the sites, when values ranged between 2.000.000 and
2.500.000 cell/l. Very low abundance values were recorded in the months of October
and November, while no findings were reported in the period December 2007-May
2008. The species abundance and the chemical-physical parameters measured data
were analyzed using univariate statistical approach (correlation matrix, Spearman
coefficient). Results from the statistical analysis highlighted a significant (α=0.05)
positive correlation among O. ovata abundance and water temperature (0.66) (Fig. 2),
conductivity (0.52), pH (0.45), a-chlorophyll (0.45), N-NO3/N-NO2 ratio (0.41), N-
NO3/N-NH4 ratio (0.41), while negative correlation with N-NO2 (-0.51). No significant
correlation was found among O. ovata abundance and N-NH4, N-NO3, N-tot., P-PO4,
P-tot., SiO2.
Conclusions – The preliminary results highlighted a well defined annual trend of the
O. ovata population in both the sites, with peaks of abundance in the summer-autumn
months and the depletion in the winter-spring period. Potential relationships among the
dinoflagellate occurrence and the water quality parameters came from the correlation
study. The seasonal variation of some chemical-physical parameters (i.e. increase of
water temperature) can be assumed as the main driver for the presence and abundance
of O. ovata, although it needs to be better investigated by an appropriate and more
extensive monitoring programme.
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41 st S.I.B.M. CONGRESS Rapallo (GE), 7-11 June 2010
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