Samples analyzed by Donato Giovannelli (mailto:donato.giovannelli@an.ismar.cnr.it) and Manini Elena (mailto:e.manini@ismar.cnr.it). For the pigment analysis sediment cores were sliced at 0-1, 1-3 and 3-5 cm layers. The analysis of chlorophyll-a (Chl-a) and phaeopigments was carried out according to Lorenzen (1980, doi:10.4319/lo.1967.12.2.0343). Pigments were extracted (12 h at 4 °C in the dark) from each layer using 5 ml of 90% acetone. Extracts were analysed fluorometrically to estimate the chlorophyll-a and phaeopigment concentration, after acidification with 200 ml 0.1N HCl. The concentrations of Chl-a and phaeopigments (expressed in µg/g of dry sediment) were summed to obtain the total chlorophyll concentration (Chloroplastic Pigments Equivalent, CPE).