Use of Posidonia oceanica seedlings from beach-cast fruits for seagrass planting

Posidonia oceanica seedlings produced from beach-cast fruits were planted in an area where this Mediterranean seagrass was lost as a consequence of fish-farming. The effects of substratum type (dead matte vs. meadow) and planting level (above vs. below bottom surface) on seedling survivorship and leaf development were evaluated after 3 years. Seedling capacity to resist uprooting was also tested by comparing survivorship and leaf development after 2 years in seedlings firmly anchored in dead matte by artificial means (mesh-pot) with those planted without any anchoring other than their roots. Survivorship in dead matte was 44% after 3 years and was not affected by planting level. Seedling planting inside the meadow led to complete mortality after 3 years. Seedlings planted below the bottom surface branched during the second year and 50% had produced from one to five additional shoots after 3 years. After 2 years, survivorship and leaf development of seedlings planted with mesh-pot anchoring was similar to that of seedlings planted without anchoring. Current environmental conditions in the impacted area allow P. oceanica seedlings to survive, but natural recovery might be limited by propagule availability. Planting of seedlings in dead matte without anchoring does not affect survivorship and leaf development and might be a feasible technique for restoration of P. oceanica meadows.