Survival and growth of transplanted and natural seedlings of Posidonia oceanica (L.) Delile in a damaged coastal area

Two pilot transplant experiments were conducted in a damaged coastal area of the Ligurian Sea (Italy) to examine the feasibility of a large-scale restoration project. Two sites were selected in the area and two-month-old aquarium-grown Posidonia oceanica (L.) Delile seedlings were transplanted at each site on different substrata. Survival and development of seedlings were followed every month. The effects of substratum type (`matte' vs. pebbles) and herbivore exclosure on seedling success were tested approximately after three years. Survival and growth of natural P. oceanica seeds germinated in the study area were also investigated. Sites did not differ significantly in the survival and development of seedlings. The highest survival and development was observed for seedlings growing on `matte', with survival rates of about 70% for transplanted and 66% for natural seedlings. Growth characteristics of natural and transplanted seedling populations were similar. Herbivores did not affect the survival and development of transplanted seedlings. These results indicate that P. oceanica seedlings may be successfully used in the study area for restoration purposes. Furthermore, our data support the hypothesis that sexual recruitment may occur in P. oceanica but could be limited by postsettlement factors relating to substratum type, in the study area.