CHAPTER 18
Diversity and Vertical Migration of Euphausiids Across the Straits
of Messina Area
G. Brancato, R. Minutoli, A. Granata, O. Sidoti, and L. Guglielmo
ABSTRACT
Samples used for this research were collected during the oceanographic cruises POP - EOCUMM
'95 (15 to 30 July 1995, N/O Italica) and carried out by a BIONESS multi net. Samples were taken
on 8 stations, in Ionian and in South Tyrrhenian Seas, across the Straits of Messina. All stations
have been sampled at regular intervals of six hours (6.00 h; 12.00 h; 18.00 h; 24.00 h). The maximum sampled depth was 2030 m. A total of 5801 specimens of juvenile and adult euphausiids,
belonging to 11 species (Thysonopodo aequo/is, Megonyctiphones norvegico, Euphausia krohni, £
brevis, £ hemigibbo, Nemotosce/is megolops, N. otlontico, Sty/ocheiron suhmi, S. longicorne, S.
obbreviatum and S. maximum) were found and species composition of the two basins was related. N. mega/ops and £ krohniwere the most common in the Ionian Sea-Straits of Messina area,
while in South Tyrrhenian Sea, T. oequalis, £ hemigibbo and S. abbreviotum were the dominant
species. Different abundance values and occurrence mean depths for juveniles and adults were
underlined in the two areas just for the most important species. Day/night vertical distributions
of the most representative species, in both areas, were studied.
Introduction
The importance of euphausiids as an active vehicle of energy flux along the water column
(Casanova 1970), as well as an important food
source for many fishes of high commercial value
(Froglia 1973, 1976), have led many researchers
to be interested in this group of crustaceans for a
very long time. A fIrst check-list, in the Straits of
Messina, was compiled by Claus (1863) and was
subsequently revised by Thiele (1905). A more
accurate study of the taxonomy and distribution
was made later by Colosi (1916,1922). From 1950
to nowadays the knowledge of euphausiids' ecology in these areas has been scarce and fragmentary. References on their presence and abundance, in Ionian and Tyrrhenian waters, were
reported by meso- and bathypelagic stranded
organisms (Guglielmo 1969; Guglielmo et al.
1973), by pelagic trawling net (Guglielmo et al.
1994), by visual observations with the
mesoscaphe "EA. Forel" {Genovese et al. 1985;
Guglielmo et al. 1994}, and also by studies on
feeding behaviour of the most common and
abundant mesopelagic fIshes of the Straits of
Messina, Myctophum punctatum and Hygophum
benoiti (Scotto Di Carlo et al. 1982).
Today 12 out of 13 mediterranean species of
euphausiids live in the Straits of Messina
(Thysanopoda aequalis. Meganyctiphanes
norvegica. Euphausia krohni, E. brevis, E. hemigibba, Thysanaessa gregaria, Nematascelis megalaps. N. atlantica, Stylocheiron suhmi, S. longicorne, S. abbreviatum and S. maximum). In fact.
only Nyctiphanes cauchi has never been collected
from the Straits of Messina even though this
species has been reported very close by in the
Ionian Sea (Ruud 1936; Casanova 1968; Wiebe
and D'Abramo 1972; Guglielmo et al. 1995a). A
more recent study about zooplankton and
micronekton vertical distribution in South
Tyrrhenian Sea (Aeolian Islands) showed that
euphausiids represent about 1.7% of the whole
community (Guglielmo et al. 1995c, 1996).
The main aim of this investigation is a study
to improve our understanding of diversity and
day/night vertical migration of euphausiids in
Tyrrhenian and Ionian basins of the Straits of
Messina hydrographic area.
Dipartimento di BiologiaAnimale ed Ecologia Marina,Universita di Messina, Italy
F.M. Faranda, L. Guglielmo, G. Spezie (eds)
Mediterranean Ecosystems: Structures and Processes
II:) Springer-Verlag Italia 2001
Diversity and Vertical Migration of Euphausiids Across the Straits
of Messina Area
G. Brancato, R. Minutoli, A. Granata, O. Sidoti, and L. Guglielmo
ABSTRACT
Samples used for this research were collected during the oceanographic cruises POP - EOCUMM
'95 (15 to 30 July 1995, N/O Italica) and carried out by a BIONESS multi net. Samples were taken
on 8 stations, in Ionian and in South Tyrrhenian Seas, across the Straits of Messina. All stations
have been sampled at regular intervals of six hours (6.00 h; 12.00 h; 18.00 h; 24.00 h). The maximum sampled depth was 2030 m. A total of 5801 specimens of juvenile and adult euphausiids,
belonging to 11 species (Thysonopodo aequo/is, Megonyctiphones norvegico, Euphausia krohni, £
brevis, £ hemigibbo, Nemotosce/is megolops, N. otlontico, Sty/ocheiron suhmi, S. longicorne, S.
obbreviatum and S. maximum) were found and species composition of the two basins was related. N. mega/ops and £ krohniwere the most common in the Ionian Sea-Straits of Messina area,
while in South Tyrrhenian Sea, T. oequalis, £ hemigibbo and S. abbreviotum were the dominant
species. Different abundance values and occurrence mean depths for juveniles and adults were
underlined in the two areas just for the most important species. Day/night vertical distributions
of the most representative species, in both areas, were studied.
Introduction
The importance of euphausiids as an active vehicle of energy flux along the water column
(Casanova 1970), as well as an important food
source for many fishes of high commercial value
(Froglia 1973, 1976), have led many researchers
to be interested in this group of crustaceans for a
very long time. A fIrst check-list, in the Straits of
Messina, was compiled by Claus (1863) and was
subsequently revised by Thiele (1905). A more
accurate study of the taxonomy and distribution
was made later by Colosi (1916,1922). From 1950
to nowadays the knowledge of euphausiids' ecology in these areas has been scarce and fragmentary. References on their presence and abundance, in Ionian and Tyrrhenian waters, were
reported by meso- and bathypelagic stranded
organisms (Guglielmo 1969; Guglielmo et al.
1973), by pelagic trawling net (Guglielmo et al.
1994), by visual observations with the
mesoscaphe "EA. Forel" {Genovese et al. 1985;
Guglielmo et al. 1994}, and also by studies on
feeding behaviour of the most common and
abundant mesopelagic fIshes of the Straits of
Messina, Myctophum punctatum and Hygophum
benoiti (Scotto Di Carlo et al. 1982).
Today 12 out of 13 mediterranean species of
euphausiids live in the Straits of Messina
(Thysanopoda aequalis. Meganyctiphanes
norvegica. Euphausia krohni, E. brevis, E. hemigibba, Thysanaessa gregaria, Nematascelis megalaps. N. atlantica, Stylocheiron suhmi, S. longicorne, S. abbreviatum and S. maximum). In fact.
only Nyctiphanes cauchi has never been collected
from the Straits of Messina even though this
species has been reported very close by in the
Ionian Sea (Ruud 1936; Casanova 1968; Wiebe
and D'Abramo 1972; Guglielmo et al. 1995a). A
more recent study about zooplankton and
micronekton vertical distribution in South
Tyrrhenian Sea (Aeolian Islands) showed that
euphausiids represent about 1.7% of the whole
community (Guglielmo et al. 1995c, 1996).
The main aim of this investigation is a study
to improve our understanding of diversity and
day/night vertical migration of euphausiids in
Tyrrhenian and Ionian basins of the Straits of
Messina hydrographic area.
Dipartimento di BiologiaAnimale ed Ecologia Marina,Universita di Messina, Italy
F.M. Faranda, L. Guglielmo, G. Spezie (eds)
Mediterranean Ecosystems: Structures and Processes
II:) Springer-Verlag Italia 2001