Benthic foraminiferal assemblages as tool for environmental characterization: the example of Gaeta Gulf, Tyrrhenian Sea, Italy

The present study is aimed at evaluating the environmental setting of Gulf of Gaeta (Tyrrhenian Sea, Western Mediterannean basin), with respect to antrophogenic and natural impacts, by mean of benthic foraminiferal assemblages. In this area, fish and molluscs farming as well as riverine run-off contribute to the characterization of the marine benthic ecosystem resulting in enrichment of organic matter content. The qualitative and quantitative foraminiferal analyses on the surface samples revealed different degree of eutrophic conditions. Five foraminiferal assemblages were recognized with a bathymetric distribution parallel to the coast. The presence of eutrophic foraminifera assemblages at about -20 m water depth in the restored area, between Punta dello Stendardo and Torre del Fico showed that the anthropogenicc activities associated with this semi-enclosed geomorphological feature caused the increase of bottom stress conditions. Here, the Garigliano river influence is weaker than in the rest of the studied section of the Gulf where the foraminiferal distribution pattern occurred in the most important river mouth of Italian coast. In particular, by proximity to the river mouth, the foraminiferal distribution seems to be controlled mainly by salinity but at higher depth (20-50 m) it is more influenced by organic matter accumulation, low oxygen conditions and dominance of infaunal species such as B. elongata, N. turgida and V.bradyana.