Macro-zoobenthic biodiversity of northern Adriatic hard substrates: Ecological insights from a bibliographic survey

A bibliographic survey of macro-zoobenthic species colonizing natural and artificial subtidal formations scattered off the Venetian coasts (North Adriatic Sea, Italy) was realized to update and organize the hard to find and fragmentary information on species lists and functional groups, with the aim to contribute to the ecological analysis of the hard substrate habitat. The results of the survey carried out at 39 sites revealed high species richness especially in the broader rocky outcrops, and a total number of species per site ranging from 13 to 142. As a whole, 399 species were recorded, mainly Mollusca, Crustacea, Annelida and Porifera. Among the recorded species, 36 were commercially valuable and 9 were included in protection lists. From a functional point of view, the category "suspension feeders" was the most numerous group. Low species evenness among the various taxa was generally observed, only few sites, specifically those more distant from the coast and/or included in protected areas, showing well-structured macro-zoobenthic communities. The analysis of taxonomic distinctness highlighted altered taxonomic structure at most sites, mainly due to changes in Mollusca assemblages, suggesting that anthropogenic stressors are likely affecting the surveyed hard substrates.