Preliminary data on benthic foraminiferal assemblages and sedimentological characterisation from some polluted and unpolluted coastal areas of Sardinia (Italy)

The relationship between living benthic foraminiferal faunas and the grain-size distribution of surface sediments was studied in three Sardinian coastal areas: a) the shallow inner shelf between Portoscuso and S. Pietro and the S. Antioco islands; b) the Porto Torres harbour; and c) the La Maddalena Archipelago. This investigation forms part of the research project "EU MOMAR". Benthic foraminifera were identified in 17 samples collected from the three analysed areas. Biotic parameters (Species' Richness, Foraminiferal Density and the Fisher-α index) were calculated to quantify the foraminiferal assemblages within the context of environmental parameters. Grain-size analyses were performed to verify the granulometric nature of the bottom sediments. On the basis of the data obtained, the spatial distribution of the foraminiferal assemblages has allowed highly to less stressed environments to be distinguished and the ecological quality status to be evaluated. The most abundant taxa are Quinqueloculina ungeriana d'Orbigny, 1846, Peneroplis pertusus (Forskal, 1775) and Ammonia tepida (Cushman, 1926) from the Portoscuso samples, P. pertusus, Quinqueloculina seminula (Linnaeus, 1758) and Q. laevigata d'Orbigny, 1839 from the Porto Torres samples and P. pertusus, Bolivina spathulata (Williamson, 1858) and Bolivina striatula Cushman, 1922 from the La Maddalena samples. Among these dominant species, Ammonia tepida and bolivinids appear to show tolerance to environmental disturbance and are therefore particularly suitable as bio-indicators in coastal areas. The sampling sites characterised by better environmental conditions present an epiphytic biocoenosis with Lobatula lobatula (Walker & Jacob, 1798), Planorbulina mediterranensis d'Orbigny, 1826, Elphidium crispum (Linnaeus, 1758) and peneroplids. Correlations are still ongoing between sedimentological features, benthic foraminiferal assemblages and chemical data from these sampled areas, with a view to understanding the environmental anthropogenic impact on coastal systems.