Sediment biogeochemical differences in two pristine Mediterranean coastal lagoons (in Italy) characterized by different phanerogam dominance - A comparative approach

1. The aim of this study was to investigate functional differences in two Italian coastal lagoons (Caprolace and Fogliano, Tyrrhenian Sea) characterized by the dominance of two different seagrass species: Cymodocea nodosa (Ucria) Ascherson in the Caprolace lagoon and Ruppia cirrhosa (Petagna) Grande in the Fogliano lagoon. 2. A monitoring system was set up in both lagoons in order to (i) map the distribution of macrophytes, (ii) measure spatio-temporal changes in the biological parameters of the seagrasses, and (iii) measure spatio-temporal changes in biological and chemical-physical parameters in the water column and sediments. 3. The results showed that the relationships between macrophytes and aquatic and sediment compartments entail functional differences described by buffering systems that counteract the accumulation of free sulphide. 4. This study also suggests that R. cirrhosa and C. nodosa are indicators of different levels of ecological stability.