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Stability of the sponge assemblage of M editerranean coralligenous concretions along a millennial time span
Author(s) -
Bertolino Marco,
Calcinai Barbara,
CattaneoVietti Riccardo,
Cerrano Carlo,
Lafratta Anna,
Pansini Maurizio,
Pica Daniela,
Bavestrello Giorgio
Publication year - 2014
Publication title -
marine ecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.668
H-Index - 58
eISSN - 1439-0485
pISSN - 0173-9565
DOI - 10.1111/maec.12063
Subject(s) - sponge spicule , sponge , paleontology , taxon , geology , biology
Abstract The M editerranean coralligenous substratum is a hard bottom of biogenic origin, mainly composed of calcareous algae, growing in dim light conditions. Sponges are among of the most representative taxa of the coralligenous assemblages, with more than 300 recorded species of different habits: massive, erect, boring and insinuating. When sponges die, their siliceous spicules remain trapped in the biogenic concretion, offering the opportunity to describe the coralligenous spongofauna over a very long span of time, virtually dating back to a large part of the H olocene period. The data reported here were obtained from core samples collected from four coralligenous concretions. Each block was collected in a different locality of the L igurian S ea: S anto S tefano S hoals, B ogliasco, P unta del F aro ( P ortofino P romontory) and P unta M anara. R adiocarbon age determinations indicate for these conglomerates a maximal age between 1600 and 3100 years. The spicules trapped in the cores show deep dissolution marks in the form of circular holes on their surface or present an enlargement of the axial canal. However, their original shape, generally intact, suggests the absence of mechanical injuries and allows a tentative identification at the species level. The analysis of these old spicules reveals an ancient sponge assemblage composed of 30 recognisable species. This indicates that almost one half of the sponge community today settled on coralligenous substrata has been present in the conglomerates for their entire existence.