Surface sediments of seagrass meadows along the Tyrrhenian continental shelf (Italy)

Mediterranean marine phanerogam Posidonia oceanica (L.) Delile forms extensive meadows, colonizing soft and hard substrates. The presence of seagrass meadows represent an important factor for the stability of coastal marine systems in subtidal range (in the Mediterranean up to ~40 mwd), influencing the sedimentary processes (KOMATSU, 1996) and representing a factory of organic matter and oxygen (JAMES, 1997). Moreover, seagrass meadows host a high variety of carbonate-producing organisms, many of which epiphytic. Their presence allows a prolific bioclastic factory (PARDI et alii, 2006). Three different meadows are investigated in the following locations, from north to south: Cala Cupa (Giglio Island, Tuscany, Northern Tyrrhenian Sea), Punta Madonna-Scoglio Rosso (Ponza Island, Latium, Central Tyrrhenian Sea, East Sector), Acquafredda di Maratea (Maratea, Basilicata, Southern Tyrrhenian Sea, East Sector). In these sampling sites, seagrass meadows are present both on soft and hard substrates, often forming "mattes". In the Giglio and Ponza islands terrigenous clasts origin only for coastal erosion on outcroppings rocks represented by volcanic rock, while in Maratea meadow terrigenous clasts origin for coastal erosion on outcroppings rocks constituted by carbonate rocks. Fluvial run-off components of Noce River, located 15 km to the south of Maratea meadow are always negligible.