Evaluation of the viability of Posidonia oceanica transplants associated with a marina expansion

Abstract In March 2005, a preliminary Posidonia oceanica transplantation was carried out as a restoration measure prior to enlargement of a marina. Seagrass sods of approximately 1 m2 surface area and 40 cm depth (including rhizome and sediment) were cut free from the area expected to be impacted by harbor expansion. These fragments were transferred to nearby areas lacking P. oceanica, viz. in bare areas within the nearest meadows and at the same depth as the donor site (∼10 m). The present work was carried out with the aim of evaluating the feasibility of this technique through estimating the vitality of transferred plants (measured as density and cover) for comparison with plants from a nearby meadow with similar conditions. There was a high level of mortality among transplants and a considerable degradation of the shoots that remained alive at the time of the sampling. When results were expressed in terms of global density, the rate of survival of transplanted shoots decreased to 15% (50 vs. 361 shoots m-2 of meadow in transplant and control plots, respectively). These results indicate that transplant techniques for P. oceanica on a large scale are not feasible.