Different thermal regimes and susceptibility to herbivory do not constrain seagrass seedling restoration

Recovering seagrass ecosystems through restoration has become impellent to re-establish their functionality and services. Although the use of seedlings may represent an appropriate solution, little information is provided on the seedling-based restoration effectiveness with influence of biotic and abiotic interactions. Survival, morphological development and leaf total phenol content of transplanted Posidonia oceanica seedlings were evaluated under different origin, thermal regimes and herbivore pressure through a five-months field experiment in two MPAs, located on the west (cold) and east (warm) Sardinia coast to explore the effectiveness of seedling-based restoration. Seedlings originated from the two coasts responded differently to thermal regime site and herbivory pressure, as the warm-adapted ones survived less but developed more (and vice-versa) and resisted to the herbivory pressure increasing their phenol content, thus showing compensating responses. This study provided information on the P. oceanica seedling-based restoration by investigating abiotic and biotic interactions with the transplanted plants. It promotes the collection of beach-cast fruits from different coasts and their transplantation, regardless their origin, with no need of protecting seedlings from predators.