CHAPTER 21
Short-term Variability of Mesozooplankton in a Mediterranean Coastal
Sound (Stagnone di Marsala, Western Sicily)
M. Campolmil, G. ZagamP, L. Guglielmol, and A. Mazzola 2
ABSTRACT
Short-term variations in mesozooplankton were studied during four 24-h periods at one station
in a Mediterranean coastal sound (Stag none di Marsala, western Sicily) in May, July and October
1996 and March 1997. Zooplankton samples were collected every three or six hours with a
plankton net (mesh size 125 pm) towed horizontally at the surface. Hydrometric data (height of
tide, speed and direction of current) were also recorded to assess the influence of the hydrodynamic conditions on fluctuations in zooplankton abundance and changes in population structure. The zooplankton assemblages were markedly dominated by copepods and their naupliar
stages, which consistently accounted for more than 95% of the total numbers. Peaks in abundance were always recorded at night, due to the increase in coastal forms (mainly of the genus
Acartia) and to a lesser extent in autochthonous forms (harpacticoids). The short-term variability of zooplankton seemed to be related both to hydrodynamic factors (tidal and wind-driven
currents) and to the nocturnal upward migration of organisms.
Introduction
The zooplankton of shallow-water systems,
coastal brackish lagoons and estuarine areas
(mainly represented by calanoid copepods) is
characterised by higher abundances and lower
values of species diversity than in offshore communities. This is mainly due to the great temporal variability of the environmental parameters
(Alcaraz 1983), which determines short- and
medium-term variability of zooplankton abundance.
Knowledge of die! variation patterns is very
important in understanding the complex
dynamics of zooplankton assemblages and their
role in the trophic webs of coastal and shallowwater systems. Zooplankton structure and spacetime distribution can significantly be influenced
by hydrodynamic factors (Haury et a1. 1978.
1990; Alldredge and Hamner 1980; Lagadeuc et
al. 1997), which contribute to a patchy distribution, but also by the daily vertical migration
(Frost 1988; Lampert 1989; Ohman 1990;
CheckIeyet al. 1992).
There have been many studies of short-term
zooplankton variability in near-shore waters or
estuaries (Sameoto 1975, 1978; Youngbluth 1980;
Gagnon and Lacroix 1981; Maranda and Lacroix
1983) and lagoons (Ferrari et al. 1985a;
Madhupratap et al. 1991; Cervetto et al. 1993).
However, there is very little or no information
about coastal environments of the central (Zagami
et aI. 1996) and southern Mediterranean Sea.
Brackish coastal habitats, generally characterised by high continental inflow and a wide
tidal range. occur in the north and centre of the
Mediterranean basin. Lagoons in the south
(especially along the North African coasts) show
small tidal effects and typical marine features,
with salinity values close to that of sea water or
even higher due to negligible runoff and a high
level of evaporation (Riggio and Chemello 1992).
The UStagnone di Marsala" is a shallow coastal
sound on the western coast of Sicily (central
Mediterranean). This hypersaline environment
has many climatic and faunal features common to
the lagoons along the North African coast (Riggio
and Chemello 1992) and represents an environment of transition between open sea and typical
lagoon systems. Until now, no information has
1 Dipartimento di Biologia Animale ed Ecologia Marina, Universita ill Messina, Salita Sperone 31,98166 Messina, Italy
2 Dipartimento ill Biologia Animale, Universita ill Palermo, Via Archirafi 18,90123 Palermo, Italy
F.M. Faranda, L. Guglielmo, G. Spezie (eds)
Mediterranean Ecosystems: Structures and Processes
@ Springer-Verlag Italia 2001
Short-term Variability of Mesozooplankton in a Mediterranean Coastal
Sound (Stagnone di Marsala, Western Sicily)
M. Campolmil, G. ZagamP, L. Guglielmol, and A. Mazzola 2
ABSTRACT
Short-term variations in mesozooplankton were studied during four 24-h periods at one station
in a Mediterranean coastal sound (Stag none di Marsala, western Sicily) in May, July and October
1996 and March 1997. Zooplankton samples were collected every three or six hours with a
plankton net (mesh size 125 pm) towed horizontally at the surface. Hydrometric data (height of
tide, speed and direction of current) were also recorded to assess the influence of the hydrodynamic conditions on fluctuations in zooplankton abundance and changes in population structure. The zooplankton assemblages were markedly dominated by copepods and their naupliar
stages, which consistently accounted for more than 95% of the total numbers. Peaks in abundance were always recorded at night, due to the increase in coastal forms (mainly of the genus
Acartia) and to a lesser extent in autochthonous forms (harpacticoids). The short-term variability of zooplankton seemed to be related both to hydrodynamic factors (tidal and wind-driven
currents) and to the nocturnal upward migration of organisms.
Introduction
The zooplankton of shallow-water systems,
coastal brackish lagoons and estuarine areas
(mainly represented by calanoid copepods) is
characterised by higher abundances and lower
values of species diversity than in offshore communities. This is mainly due to the great temporal variability of the environmental parameters
(Alcaraz 1983), which determines short- and
medium-term variability of zooplankton abundance.
Knowledge of die! variation patterns is very
important in understanding the complex
dynamics of zooplankton assemblages and their
role in the trophic webs of coastal and shallowwater systems. Zooplankton structure and spacetime distribution can significantly be influenced
by hydrodynamic factors (Haury et a1. 1978.
1990; Alldredge and Hamner 1980; Lagadeuc et
al. 1997), which contribute to a patchy distribution, but also by the daily vertical migration
(Frost 1988; Lampert 1989; Ohman 1990;
CheckIeyet al. 1992).
There have been many studies of short-term
zooplankton variability in near-shore waters or
estuaries (Sameoto 1975, 1978; Youngbluth 1980;
Gagnon and Lacroix 1981; Maranda and Lacroix
1983) and lagoons (Ferrari et al. 1985a;
Madhupratap et al. 1991; Cervetto et al. 1993).
However, there is very little or no information
about coastal environments of the central (Zagami
et aI. 1996) and southern Mediterranean Sea.
Brackish coastal habitats, generally characterised by high continental inflow and a wide
tidal range. occur in the north and centre of the
Mediterranean basin. Lagoons in the south
(especially along the North African coasts) show
small tidal effects and typical marine features,
with salinity values close to that of sea water or
even higher due to negligible runoff and a high
level of evaporation (Riggio and Chemello 1992).
The UStagnone di Marsala" is a shallow coastal
sound on the western coast of Sicily (central
Mediterranean). This hypersaline environment
has many climatic and faunal features common to
the lagoons along the North African coast (Riggio
and Chemello 1992) and represents an environment of transition between open sea and typical
lagoon systems. Until now, no information has
1 Dipartimento di Biologia Animale ed Ecologia Marina, Universita ill Messina, Salita Sperone 31,98166 Messina, Italy
2 Dipartimento ill Biologia Animale, Universita ill Palermo, Via Archirafi 18,90123 Palermo, Italy
F.M. Faranda, L. Guglielmo, G. Spezie (eds)
Mediterranean Ecosystems: Structures and Processes
@ Springer-Verlag Italia 2001