Planktonic foraminifera as bio-indicators for monitoring the climatic changes that have occurred over the past 2000 years in the southeastern Tyrrhenian Sea

A high-resolution integrated study has been performed in a super-expanded marine record (sedimentation rate spanning from 11 cm/100 years to 20 cm/100 years) from the continental shelf area of the southeastern Tyrrhenian Sea. Planktonic foraminiferal distribution illustrates 6 major environmental changes during the past 2000 years: (i) the Roman Period-Dark Age transition (from herbivorous-opportunistic to carnivorous species); (ii) the Dark Age-MCA transition (from carnivorous to herbivorous-opportunistic species); (iii) the Medieval Classic Anomaly-Little Ice Age transition (a further and definitive change from carnivorous to herbivorous-opportunistic species); (iv) the period during the Maunder event between approximately 1720 AD and 1740 AD (turnover from the carnivorous planktonic foraminifer Globigerinodes ruber to the herbivorous-opportunistic planktonic foraminifer Turborotalita quinqueloba); (v) the Industrial Period (dominance of herbivorous-opportunistic planktonic foraminifera); and (vi) the Modern Warm Period at approximately 1940 AD (the last turnover in favor of herbivorous-opportunistic planktonic foraminifers, associated with an increase in benthic foraminifera). Our studies lead us to link this latter feature to an anthropogenic impact associated with the damming of Sele River (Salerno Gulf) at 1934 AD, which induced a change in the sediment input with a strong decrease in coarse-grained fraction and a probable alteration in nutrient supply. The delta O-18(G. ruber) record of the past 2000 years shows the alternation of warm/wet and cold/dry events related to the Roman Period, the Dark Age, the Medieval Classic Anomaly, the Little Ice Age, the Industrial Period and the Modern Warm Period. The 5 evident delta O-18(G. ruber) oscillations (between approximately 1325 AD and 1940 AD) coincide with the 5 minima in the solar activity record (Wolf, Sporer, Maunder, Dalton and Damon events).