A citizen science approach for the genetic analysis of a Posidonia oceanica meadow in the Italian Southern Adriatic sea.

A citizens’ observatory, the Osservatorio del Mare a Molfetta (OMM), monitors the health status of the marine/coastal environment of the city. Posidonia oceanica (Linnaeus) Delile meadows are considered as bioindicators revealing the health status of the related marine/ coastal ecosystem. To gather information necessary for the preservation of this ecosystem, OMM investigated the health status of the local San Vito-Barletta P. oceanica meadow extend- ing along the coast of the Apulia region in the Italian Southern Adriatic Sea, which has been lately graded as ‘disturbed’. Volunteers conducted underwater visual census of the epiphytes on P. oceanica leaves. Two campaigns of investigations at three different stations, namely Molfetta, Giovinazzo and Mola di Bari, evidenced differences in the distribution of the epiphytic commu- nities. furthermore, a population genetics study performed together with a scientific research centre using highly variable microsatellite markers showed an excess of heterozygosity and demonstrated the existence of at least two subpopulations within the meadow. Since the sam- pling areas were situated along the coasts of different urban centers, this situation may reflect the diverse anthropogenic pressures differing from city to city. Therefore, this study highlights the need to promote good conservation practices to preserve the San Vito-Barletta meadow and the whole related coastal/marine ecosystem