Planktonic foraminifera in the last 500 years in the southern Tyrrhenian sea: paleoclimatic implications

In the last few years, several high-resolution integrated studies have been carried out on different sedimentary archives to understand the climatic behaviour during the last millennium. The Mediterranean area is considered a natural laboratory for studying the evolution of the marine climate system. In particular, the Southern Tyrrhenian margin, characterised by high sedimentation rates and by occurrence of tephra layers, represents a key area where it is possible to detect the main climatic oscillations of the last millennium. Undisturbed and continuous marine sedimentary record has been recovered from a gravity core at 103.4 mbsl in the Southern Tyrrhenian margin (Salerno Gulf) for a total of 106 cm. The record has been analysed by a multiproxy stratigraphic approach. An accurate time framework has been obtained thought the combination of 210Pb and 137Cs chronology, AMS 14C data and analysis of the tephra deposits interbedded within the marine succession. The obtained age-model suggested an high sedimentation rate of about 0.20 cm/year for the last 500 years. The quantitative analysis of planktonic foraminifera suggests that variation in foraminiferal fluxes were strongly influenced by the climatic oscillation occurring during the last 500 years. In particular, a good correlation exists between the total number gr-1of planktonic foraminifera maxima with Total Solar Irradiance (TSI) minima. This correlation is confirmed by the increase in abundance of Globigerina bulloides and Turborotalita quinqueloba and by the decrease of Globigerinoides ruber during the cold periods. These data allowed us to recognise the Little Ice Age (LIA) with the identification of the great low solar activity events known as the Sporer Minima, Maunder Minima, Dalton Minima, and the last minima known as Damon. Moreover, the strong increase in abundance of G. bulloides and G. quadrilobatus from years 1950-60 upwards suggests an increase of food availability enhanced by upwelling and/or river input. These data may be associated to the modern global warming.