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Climate variability of the last ~2700 years in the Southern Adriatic Sea: Coccolithophore evidences

PUBBLICATO: 2 Agosto 2019
Fig. 1
Figure 1. Location of the cores SW104-ND14Q (diamond), C5 Composite (dot), C90 (square, Lirer et al., 2013), Basa de la Mora (star, Moreno et al., 2012) and Ledro (triangle, Wirth et al., 2013): (a) bathymetric map of the Mediterranean Basin and main surface (green arrow) and intermediate circulation pattern (red arrow). AC: Algerian Current; MAW: Modified Atlantic Water; ATC: Atlantic Tunisian Current; LIW: Levantine Intermediate Water. Numbers 1–6: 1: Alboran Sea; 2: Tyrrhenian Sea; 3: Adriatic Sea; 4: South Adriatic Pit, SAP; 5: Ionian Sea; 6: Levantine Sea. The main catchment basins of river flowing into the Adriatic Sea are reported (blue thick lines). (b) and (c): bathymetric map and main circulation pattern of South Adriatic Sea and North Ionian Sea during cyclonic (b) and anticyclonic (c) mode of the BiOS. WAC: Western Adriatic Current; EAC: Eastern Adriatic Current; LIW: Levantine Intermediate Water; MAW: Modified Atlantic Water; SAG: South Adriatic Gyre; NIG: North Ionian Gyre.

Cascella A., S. Bonomo, B. Jalali, M.A. Sicre, N. Pelosi, S. Schmidt, F. Lirer (2019).
The Holocene, https://doi.org/10.1177/0959683619865600.

Abstract

New information on palaeoenvironmental conditions over the past ~2700 years in the Central Mediterranean Sea have been acquired through the high-resolution study of calcareous nannofossils preserved in the sediment core SW104-ND14Q recovered in the Southern Adriatic Sea (SAS) at 1013-m water depth. The surface water properties at this open SAS site are sensitive to atmospheric forcing (acting both at local and regional scale) and the North Ionian Sea driven inflowing waters. Our data show a relationship between reworked coccolith abundances, flood frequency across the Southern Alps and the North Atlantic Oscillation (NAO) confirming their value as indicator of runoff/precipitation. Changes in the abundance of the opportunistic (r-strategist) species Emiliania huxleyi and deep dweller taxa Florisphaera profunda were used to reconstruct the upper water column stratification and associated changes in coccolithophorid productivity. The negative correlation between reworked coccoliths and the N-Ratio (r = −0.44; p = 6−7) suggest that fresh water induced stratification is a controlling factor of the SAS coccolithophorid production. High coccolithophorid productivity levels occurred during dry periods and/or time intervals of inflowing salty and nutrient-rich Levantine Intermediate Waters favouring convection while lower levels took place during high freshwater discharge, mainly during the ‘Little Ice Age’ and two centennial scale intervals of weakest NAO around 200 BCE and 500 CE.

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