CHAPTER 26
Diel Feeding Features of Juveniles of Two Sparids in the Stagnone
di Marsala Coastal Sound (Western Sicily, Italy)
L Lopiano, S. Mirto, D. Sdlipoti, and A. Mazzola
ABSTRACT
Diet composition, feeding rhythms, gastric evacuation rates, daily rations of Dip/odus puntazzo
(Gmelin 1789) and Sarpa sa/po (Linneo 1758) juveniles were studied in order to investigate their
trophic ecology, niche breadth and overlap. These Sparids were collected in the Stag none di
Marsala {Western sicilyt in April 1997, in a 24 hour sampling period. Gastric content of 86 specimens of D. puntazzo (standard length = 31.9 ± 6.6 mm; body wet weight = 1.0 T 0.5 g) and of 100
specimens of S. sa/pa (standard length = 32.3 ± 2.9 mm; body wet weight = Q.6 T 0.2 g) were
examined. Amphipoda and Tanaidacea were the most frequent prey items in stomach content
of D. puntazzo, while Hydrozoa, Bryozoa and Rhodophycaea were the most frequent prey items
in that of S. sa/pa. Both species displayed high frequency of occurrence (% Fr) of Copepoda and
Ascidiacea larvae. A unimodal trend of daily rhythm of food consumption was deduced for both
species. Gastric evacuation of juvenile D. puntazzo was best described by a square root model,
with a gastric evacuation rate R= 0.011 ± 0.001 (r= 0.84; n= 28; P< 0.001). Similarly, gastric evacuation of S. sa/pa followed a square root model, with a gastric evacuation rate R = 0.014 ± 0.001
(r = 0.90; n = 42; P < 0.001). The amount of food consumed daily, calculated according to
Pennington's model, was 0.0133 g dry weight g-1 body dry weight for D.puntazzo and 0.0159 g
dry weight g-1 body dry weight for S. sa/po, equal to 1.3% and 1.6% of the average body dry
weight, respectively. Standardised Levins' index (B A ), calculated on percent volume (% V), suggested that juveniles of D.puntazzo have a niche breadth (mean standardised Levins' index = 0.2
± 0.02) larger than the one of S. sa/pa (mean standardised Levins' index = 0.1 ± 0.01) at most
sampling times. Juvenile specimens of these two sparids presented a niche overlap at 4 pm, in
correspondence with their feeding peak (Simplified Morisita's index C H = 0.9), Feeding habits of
D. puntazzo and S. sa/pa and their niche overlap are discussed in comparison with literature
available on the same field.
Introduction
Diplodus puntazzo and Sarpa salpa are two
species of Sparids very common along the
Mediterranean coasts. They can also be found in
the Black Sea and in the Atlantic Ocean, from the
Bay of Biscay to South Africa, where they live on
rocky bottoms covered by vegetation. Adults of
D. puntazzo usually live alone or in small groups
down to a depth of 50 metres, while adults of S.
salpa live in the upper water layer and have
strong gregarious habits (Tortonese 1975).
Juveniles of these two species usually live near
the coast (Macpherson 1998), in shallow and
sheltered waters, that they selected as "nursery
areas". Several studies are available on feeding
habits and microhabitat requirements of these
two Sparids. in relationship with other fish
species (Porcile et al. 1987; Antolic et al. 1994;
Mirto et al. 1994; Harmelin-Vivien et al. 1995;
Sala and Ballesteros 1997; Planes et a1. 1999).
The aims of this study are: (1) to point out
diel feeding habits, niche breadth and overlap of
juveniles of D. puntazzD and S. salpa in a typical
Mediterranean shallow coastal environment; (2)
to study feeding rhythm and daily food consumption of young D. puntazzo and S. salpa.
Dipartimento di Biologia Animale, Universita di Palermo, Via Archirafi 18,90123 Palermo. Italy
F.M. Faranda, 1. Guglielmo, G. Spezie (eds)
Mediterranean Ecosystems: Structures and Processes
I!ll Springer-Verlag ItaIm 2001
Diel Feeding Features of Juveniles of Two Sparids in the Stagnone
di Marsala Coastal Sound (Western Sicily, Italy)
L Lopiano, S. Mirto, D. Sdlipoti, and A. Mazzola
ABSTRACT
Diet composition, feeding rhythms, gastric evacuation rates, daily rations of Dip/odus puntazzo
(Gmelin 1789) and Sarpa sa/po (Linneo 1758) juveniles were studied in order to investigate their
trophic ecology, niche breadth and overlap. These Sparids were collected in the Stag none di
Marsala {Western sicilyt in April 1997, in a 24 hour sampling period. Gastric content of 86 specimens of D. puntazzo (standard length = 31.9 ± 6.6 mm; body wet weight = 1.0 T 0.5 g) and of 100
specimens of S. sa/pa (standard length = 32.3 ± 2.9 mm; body wet weight = Q.6 T 0.2 g) were
examined. Amphipoda and Tanaidacea were the most frequent prey items in stomach content
of D. puntazzo, while Hydrozoa, Bryozoa and Rhodophycaea were the most frequent prey items
in that of S. sa/pa. Both species displayed high frequency of occurrence (% Fr) of Copepoda and
Ascidiacea larvae. A unimodal trend of daily rhythm of food consumption was deduced for both
species. Gastric evacuation of juvenile D. puntazzo was best described by a square root model,
with a gastric evacuation rate R= 0.011 ± 0.001 (r= 0.84; n= 28; P< 0.001). Similarly, gastric evacuation of S. sa/pa followed a square root model, with a gastric evacuation rate R = 0.014 ± 0.001
(r = 0.90; n = 42; P < 0.001). The amount of food consumed daily, calculated according to
Pennington's model, was 0.0133 g dry weight g-1 body dry weight for D.puntazzo and 0.0159 g
dry weight g-1 body dry weight for S. sa/po, equal to 1.3% and 1.6% of the average body dry
weight, respectively. Standardised Levins' index (B A ), calculated on percent volume (% V), suggested that juveniles of D.puntazzo have a niche breadth (mean standardised Levins' index = 0.2
± 0.02) larger than the one of S. sa/pa (mean standardised Levins' index = 0.1 ± 0.01) at most
sampling times. Juvenile specimens of these two sparids presented a niche overlap at 4 pm, in
correspondence with their feeding peak (Simplified Morisita's index C H = 0.9), Feeding habits of
D. puntazzo and S. sa/pa and their niche overlap are discussed in comparison with literature
available on the same field.
Introduction
Diplodus puntazzo and Sarpa salpa are two
species of Sparids very common along the
Mediterranean coasts. They can also be found in
the Black Sea and in the Atlantic Ocean, from the
Bay of Biscay to South Africa, where they live on
rocky bottoms covered by vegetation. Adults of
D. puntazzo usually live alone or in small groups
down to a depth of 50 metres, while adults of S.
salpa live in the upper water layer and have
strong gregarious habits (Tortonese 1975).
Juveniles of these two species usually live near
the coast (Macpherson 1998), in shallow and
sheltered waters, that they selected as "nursery
areas". Several studies are available on feeding
habits and microhabitat requirements of these
two Sparids. in relationship with other fish
species (Porcile et al. 1987; Antolic et al. 1994;
Mirto et al. 1994; Harmelin-Vivien et al. 1995;
Sala and Ballesteros 1997; Planes et a1. 1999).
The aims of this study are: (1) to point out
diel feeding habits, niche breadth and overlap of
juveniles of D. puntazzD and S. salpa in a typical
Mediterranean shallow coastal environment; (2)
to study feeding rhythm and daily food consumption of young D. puntazzo and S. salpa.
Dipartimento di Biologia Animale, Universita di Palermo, Via Archirafi 18,90123 Palermo. Italy
F.M. Faranda, 1. Guglielmo, G. Spezie (eds)
Mediterranean Ecosystems: Structures and Processes
I!ll Springer-Verlag ItaIm 2001