Hydrobiologia 449: 123–130, 2001.
J.P.M. Paula, A.A.V. Flores & C.H.J.M. Fransen (eds), Advances in Decapod Crustacean Research.
© 2001 Kluwer Academic Publishers. Printed in the Netherlands.
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Sex-related variability of rostrum morphometry of Aristeus antennatus
(Decapoda: Aristeidae) from the Ionian Sea
(Eastern Mediterranean, Greece)
Kostas Kapiris & Maria Thessalou-Legaki
Dept. of Zoology-Marine Biology, University of Athens, Panepistimioupolis, GR 157 84 Athens, Greece
Key words: A. antennatus, rostrum relative growth, Ionian Sea, Mediterranean, Decapoda, Aristeidae
Abstract
Sex-related rostral variability was studied in the aristeid shrimp Aristeus antennatus from the Eastern Ionian Sea
(Mediterranean). Shrimps were collected on a monthly basis from December 1996 to November 1997 using a
commercial bottom trawl in a depth range of 446–728 m. Female relative growth of rostrum proved to be negative
allometric both seasonally and in the pooled annual data set. Males on the other hand, showed no or negative
correlation of rostrum length with size. Mature males with short rostra dominated in the male population all year
around. The appearance of males with long and intermediate rostra during winter, which disappear thereafter
in favour of those with short rostra, indicates that rostrum shortening takes place during the end of winter. The
increase of mated females during spring supports the hypothesis already addressed by other authors on the function
of the male short rostrum in this species mating behaviour. Nevertheless, the paucity, in comparison to other
Mediterranean populations, of males with long or intermediate rostra could indicate that for the bulk of the male
population, the process of rostrum shortening in the Eastern Ionian Sea occurs outside the geographical locality or
depth range sampled.
Introduction
The shrimp Aristeus antennatus (Risso, 1816) is a
common species of the upper and middle slope in the
Western Mediterranean and adjacent seas (Sardà et al.,
1998; Carbonell et al. 1999). It is a target species of
the deep-water demersal trawl fishery in the Western
and Central Mediterranean. In the Italian Ionian Sea,
A. antennatus, together with the other aristeid shrimp
Aristaeomoprha foliacea, represents the most valu-
able species of trawl fishing (Matarrese et al., 1994).
Despite the abundant information on the biology and
population dynamics available for Western Mediter-
ranean (see Bas & Sardà, 1998 for references) and
Western Ionian Sea stocks (in Bianchini & Ragonese,
1994), only scanty data exist on A. antennatus dis-
tribution and biology in the Eastern Mediterranean
(Thessalou-Legaki, 1994; NCMR, 1999; Kapiris et al.,
2000).
The study of the functional morphometry, car-
ried out in a number of A. antennatus body parts
from Western Mediterranean populations, has revealed
adaptive differences between size groups and sexes.
These differences have been related to differences
in swimming and/or feeding behaviour (Sardà et al.,
1995). Furthermore, morphometric analyses showed
significant differences between populations from a
number of localities along the Mediterranean and the
adjacent Atlantic waters, while genetic analyses of
27 enzyme systems gave a rather weak evidence for
genetic differentiation (Sardà et al., 1998). Finally,
long-term changes over a 30-year period of the relative
growth of some female body parts have been detected
by Bas & Sardà (1998), being attributed to increasing
fishing pressure.
Rostral variability is commonly found in aristeid
shrimps. It is known to be related to sex, sexual
maturity and size (Burukovsky & Romensky, 1972).
Burukovsky (1972) related rostral function with habi-
tat of several shrimp species, while Palombi (1939)
stated that short rostrum in mature males is used in
mating behaviour. Nevertheless, other rostral func-