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4                       F. MARRONE & G. MURA

                corpi d’acqua ad idroperiodo temporaneo, ecosistemi che ospitano un biota ricco e peculiare di cui
                i grossi branchiopodi sono “specie bandiera”.

                    With a surface area of about 26,000 km , Sicily is the biggest Mediter-
                ranean island. According to the De Martonne-Gottmann’s algorithm most of
                its territory is subjected to arid or semi-arid conditions (DURO et al. 1997). As
                precipitation are concentrated in winter months, Sicilian climate is charac-
                terised by hot, dry summers and mild, wet winters. The annual average tem-
                perature ranges between 11 °C (Floresta, Messina province) and 20 °C (Gela,
                Caltanissetta province), and the average precipitation varies between 385
                mm/year (Gela, Caltanissetta province) and 1192 mm/year (Zafferana etnea,
                Catania province). The high water deficit characteristic of the summer months
                causes the lack of a well-developed permanent surface hydrographical net-
                work; conversely, temporary water bodies are widely spread throughout the
                island and represent the most common and peculiar Sicilian inland water
                ecosystems. As a consequence, studying their biota is of pivotal importance in
                order to correctly understand the autochthonous Sicilian freshwater fauna.
                    Its position in the centre of the Mediterranean basin makes Sicily a
                potential active transition zone for freshwater invertebrates, at least as far as
                freshwater zooplankton is concerned (NASELLI-FLORES et al., 1998). Unfor-
                tunately, an exhaustive survey on the distribution of Sicilian large bran-
                chiopods, the “flagship group” of temporary waters biota, is lacking and
                reports on the species are sparse. The purpose of this paper is to contribute
                to review and integrate the current knowledge on large branchiopod crus-
                taceans in the Mediterranean basin by providing data on their distribution,
                phenology and status in Sicily.

                    During the ponding phase of the water bodies, samples were collected
                by means of 125 µm mesh towing net and 200 µm mesh hand net, preserved
                in 90% ethanol or buffered formaldehyde (4%), and stored in the authors’
                collections. During the dry phase, core samples were collected from the edge
                and from the deepest point of the depressions studied. Core samples were
                afterwards partly rehydrated in the laboratory at room temperature and part-
                ly sieved with a 125 µm mesh sieve in order to sort out the resting eggs. Iden-
                tification of adult specimens was performed according to DADAY DE DEÉS
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