Biogeosciences
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4
4
2007
10.5194/bg-4-673-2007
http://www.biogeosciences.net/4/673/2007/
http://www.biogeosciences.net/4/673/2007/bg-4-673-2007.html
http://www.biogeosciences.net/4/673/2007/bg-4-673-2007.pdf
673
687
2007-08-22
NW Adriatic Sea biogeochemical variability in the last 20 years (1986–2005)
L. Tedesco
letizia.tedesco@cmcc.it
G. Socal
F. Bianchi
F. Acri
D. Veneri
M. Vichi
Centro Euro-Mediterraneo per i Cambiamenti Climatici (CMCC), Bologna, Italy
University of Bologna, Centro Interdipartimentale di Ricerca per le Scienze Ambientali (CIRSA), Ravenna, Italy
CNR – ISMAR, Istituto di Scienze Marine, Venezia, Italy
Istituto Nazionale di Geofisica e Vulcanologia, Bologna, Italy
This paper presents a long-term time series (1986–2005) of hydrological and
biogeochemical data, both published and unpublished. Data were collected in
the north-western area of the Adriatic Sea, at two stations that are
considered hydrodynamically and trophically different. The time series have
been statistically and graphically analysed on a monthly scale in order
to study the annual climatologies, links between the concentrations of
chlorophyll-<i>a</i> and the variability in the environment, trophic differences
between the two areas and chlorophyll-<i>a</i> trends over time. Basically,
the two areas have similar hydrological features, yet they present significant differences
in the amount of nutrient inputs: these are in fact higher at the coastal site, which is
characterized by a prevalence of surface blooms, while they are lower at the offshore station,
which is mainly affected by blooms at intermediate depths. Nonetheless, throughout the whole water
column, chlorophyll-<i>a</i> concentrations are only slightly different.
Both areas are affected by riverine discharge, though chlorophyll-<i>a</i> concentrations are also
driven strongly by the seasonal cycle at the station closer to the coast. Results show that the two stations are not
trophically different, although some controlling factors, such as zooplankton
grazing in one case and light attenuation in the other, may further regulate the
growth of phytoplankton. In both cases no significant trends are detected in either the
average chlorophyll-<i>a</i> values or in dispersion of the data, in contrast with
significant trends in temperature and salinity.
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