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Planktonic foraminifera as bio-indicators for monitoring the climatic changes occurred during the last 2000 years in the SE Tyrrhenian Sea

January 16, 2014

A high-resolution integrated study has been performed in a super-expanded marine record (sedimentation rate spanning from 11 cm / 100 yr to 20 cm / 100 yr) from the continental shelf area of the SE Tyrrhenian Sea. Planktonic foraminiferal distribution illustrates six major environmental changes during the last 2000 years: i) Roman period – Dark Age transition (from herbivorous-opportunistic to carnivorous species); ii) Dark Age – Medieval Classic Anomaly transition (from carnivorous to herbivorous-opportunistic species; iii) 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 ca. 1740 AD and ca. 1760 AD (turnover from the carnivorous planktonic foraminifer Globigerinodes ruber to the herbivorous-opportunistic planktonic foraminifer Turborotalita quinqueloba; v) Industrial period (dominance of herbivorous-opportunistic planktonic foraminifera) and vi) Modern warm period at ca. 1940 AD (the last turnover in favour 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 δ18OG. ruber record of the last 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, Industrial period and the Modern warm period. The five evident δ18OG.ruber oscillations (between ca. 1240AD and ca. 1940 AD) coincide with the five minima in the solar activity (Wolf, Spörer, Maunder, Dalton and Damon events).

Lirer F, Sprovieri M, Vallefuoco M, Ferraro L, Pelosi, Giordano L, Capotondi L, in press. Planktonic foraminifera as bio-indicators for monitoring the climatic changes occurred during the last 2000 years in the SE Tyrrhenian Sea, Integrative Zoology, 2014, doi:. Article.

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