Integrative taxonomy for the characterization of the hard-bottom communities in a Long-term Ecological Research (LTER) site of the North Adriatic Sea

The Northern Adriatic Sea is the northernmost, closed and shallowest region of the Mediterranean, with an intense human activity (mainly fishing) threatening the local marine biodiversity. To ensure the preservation of benthic biodiversity, monitoring become essential. A promising method involves the use of artificial substrates, specifically passive samplers like the Autonomous Reef Monitoring Structures (ARMS). ARMS, resembling stacked settlement plates on the seafloor, mimic the complexity of hard-bottom marine substrates. They attract a variety of sessile and vagile benthic organisms, providing a standardized way of recording benthic communities. A part the use of standardized methods to assess changes in the benthic communities, also identify sites that can be monitored trough time is essential. In the North Adriatic Sea one of this site, named Long Term Monitoring site, is “Acqua Alta Oceanographic platform", installed about 8 miles off the coast of Venice. Here, I evaluate the change in the benthic communities grown on ARMS deployed in 2021 and 2022. The most abundant phyla were Annelida (30 taxa), Arthropoda (27) and Mollusca (23). Statistically, no significant differences were reported in the diversity indices between years. However, the 2021 community structure was statistically significant different from 2022. Despite, I did not analyse environmental parameters, they may, however, explain the observed differences. Furthermore, the fauna detected was not so similar to that observed in the hard-bottom outcrops ('tegnue') close to the platform suggesting that species recruited on ARMS could arrive from somewhere else. To improve our knowledge of changes in the benthic community at this site, it is important to encourage and maintain the long-term research and integrate abiotic parameters to explain any future differences.