Sponges associated with coralligenous formations along the Apulian coasts

Abstract

Sponge assemblages associated with coralligenous outcrops were studied with the aim of describing and comparing their composition, morphological features and distribution at different depths (shallow vs. deep) along the Apulian coasts. In addition, image analysis enabled the description of the main features of coralligenous outcrops and the detection of structuring species. The paper provides a significant contribution in terms of supplying new taxa of sponges associated to coralligenous assemblages and emphasising the importance of invertebrates in realising calcareous constructions. Most of the new finding came from deep sites, thus underlining the need to improve taxonomic studies on coralligenous communities at greater depths. A total of 153 taxa of sponges were recorded: 4 Calcarea, 6 Homoscleromorpha and 143 Demospongiae. Two species, Clathria (Microciona) macrochela and Thoosa armata, are new records for the Italian sponge fauna, with C. (M.) macrochela representing a new record for the whole Mediterranean. New findings for the Ionian and Adriatic Seas totalled 25 and 8 species, respectively. Thirty-nine species are endemic for the Mediterranean. Data analyses clustered sites into two groups, separated according to the depth. Deep sites, characterised by animal dominance, exhibit a heterogeneous substrate texture richer in cavities than the shallow and homogeneous algal ones. Differences in sponge species composition also correspond to differences in the distribution of sponge growth forms, with the insinuating cryptic species more abundant in deeper communities. Ten of 15 sponge species included in national and international wildlife protection laws and policy have been detected in the present study.