From leaves to genes: an integrated approach to Cymodocea nodosa (Ucria) Ascherson meadow in the Central Adriatic Sea

Meadows of Cymodocea nodosa have a well-known ecological value, recognized by the Barcelona Convention and the EU Habitat Directive. Since many seagrasses worldwide have declined due to human-induced disturbances and climate change, the aim of this study was to assess the status of a C. nodosa meadow in Ancona, in a semi-sheltered site located in an impacted area of the Central Adriatic Sea. For the first time this meadow was systematically monitored from May to October 2024, based on a random nested sampling design. The work consisted of shoot density counting by snorkelling, searching for flowers, measuring structural parameters, and taxonomic identification of the leaves epibiota. Results confirmed the species seasonal Mediterranean behaviour, with a peak of growth in July and a decline in Autumn, and the rarity of the sexual reproduction. Moreover, a temporal variation of the epibiota composition was highlighted, with a dominance of red algae (Rhodophyta). Overall, the results highlighted a good status of the meadow and high diversity of the associated epibiota, confirming the importance of monitoring the meadow. Therefore, monitoring of the meadow is still ongoing (INTERREG Brigantine project), extending to additional portions and combining the previously mentioned methods with multispectral images provided by a multiprobe aquatic drone and eDNA metabarcoding.