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during two oceanographic cruises aboard of the oceanographic ship “Bannock”. The
first cruise took place on July-August 1983 in the Ustica Island, Egadi and Aeolian
Archipelagos, the second one took place on October 1984 in the Partenopean and
Pontine Archipelagos. On the whole, crustaceans were present in 171 sampling stations
between 22 and 540 m depth, distributed as follow: 29 Egadi Islands, 11 Ustica Island,
39 Aeolian Islands, 31 Partenopean Islands and 61 Pontine Islands. We found 1001
individuals belonging to 184 species. Only 6 species were common to the four
archipelagos and Ustica Island, and for one of them, the decapod Monodaeus guinotae
Forest, 1976, there are few records in Mediterranean; while 71 species (38.6 %)
compared once. On the whole, Ustica Island reached a highest values of number of
individuals (on average 18.4±5.1), number of species (on average 4.9±1.4) and Shannon
diversity (on average 1.7±0.5), the lowest values were observed at the Aeolian
Archipelago (on average 3.3±0.5, 2.2±0.3 and 0.8±0.1 for individuals number, species
number and diversity respectively). The multivariate analysis showed a low similarity
within archipelagos and the high dissimilarity between them (on average 83.1±5.5). In
the cluster plot it was not possible to identify a characteristic zonation for Archipelago;
but when the analysis was performed considering depths, stations were divided into two
groups: one representing the stations with depth above 100 m, characterised by detrital
sediments, and the second representing the stations with depth below 100 m
characterised by mixed or muddy sediments. So, depth and sediment characteristics
rather than geographic location seem to influence the crustacean zonation in the South
Tyrrhenian Archipelagos and Ustica Island.

1. INTRODUCTION

The South part of the Tyrrhenian Sea is characterised by the presence of many
islands and archipelagos. More of them have been proposed as marine protected areas
by means of the law 979/82. Until now, are effectively instituted: the “Natural marine
riserve Ustica Island” (1986), the “Natural marine riserve Egadi Islands” (1989), and the
“National natural riserve Ventotene and Santo Stefano Islands” (Pontine Archipelago,
1999). The other archipelagos will be instituted in the next future.

In general, there is little information about benthic assemblages of the Southern
Tyrrhenian (Russo et al., 1983-84; Gravina et al., 1992; Matarrese et al., 1995; 1996;
Terlizzi & Russo, 1995; 1996; Giacobbe et al., 1997; Giacobbe & Spanò, 1998; Milazzo
et al., 2000; 2001; Covazzi Harriague et al., 2002). In particular, paper of crustacean
populations are restricted to assemblages linked to the Posidonia meadows of the Ischia
Island (Mazzella et al., 1989; Lorenti & Scipione, 1990; Gambi et al., 1992; Scipione
1992).

The aim of the study is:
• to characterise the crustacean assemblages of the South Tyrrhenian Archipelagos

(Egadi, Aeolian, Pontine and Partenopean) and Ustica Island before of the
institution of the Marine protected areas,
• to verify the similarity or differences between archipelago populations.

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