Posidonia oceanica meadows of the Italian southern Adriatic Sea display different genetic structure

The Mediterranean-endemic seagrass Posidonia oceanica (L.) Delile forms meadows of great ecological importance that are currently under high anthropogenic pressures. We investigated the genetic structure of two meadows located in the Adriatic Sea along the coast of Italy. The San Vito-Barletta meadow is located in an unprotect area close to several medium-large towns suggesting that it is more subjected to a wide panel of anthropic impacts. This meadow displays subpopulation structure and higher genetic/genotypic diversity which may be the consequence of a combination of different anthropic impacts and environmental features. In contrast, the Tremiti Islands meadow is included within a marine protected area away from large cities. Genetic analysis showed that this meadow possesses a monoclonal structure with low genetic/genotypic diversity. Yet, our data indicate that both meadows require specific conservation/restoration policy.