Variabilità spaziale e temporale dei popolamenti epibentonici sommersi delle Isole Tremiti

The present study aimed at estimating the spatial distribution and temporal variation of epibenthic assemblages Tremiti Islands (42° 07’ North 15° 30’ East) by photographic sampling from 2012 to 2015 at 2 randomly selected areas within 2 sites and at 2 depths (6 and 18 m depth). Overall, 65 taxa were identified. The dominant taxa were Peyssonnelia spp., Dyctiotales, Codium bursa, Codium effusum, Halimeda tuna, Pseudochlorodesmis furcellata, algal turf, Ircinia spp., Chondrosia reniformis and Rocellaria dubia. Composition of the assemblages varied through years and among sites. As a general pattern, shallower assemblages were more variable in time. Although the study was limited to the euphotic zone, these observations support the general tendency, already described in deeper investigations, toward greater stability and less dynamism with increasing depth. Result indicated that patterns of distribution and abundance of organisms differed between the two depths for all the years. The assemblages showed a high diversity, especially in relation to the smaller spatial scale examined. Sites clearly differed in the abundance of the main taxa and some taxa showed site-specific trend. Coralligenous outcrops rank among the most important ecosystems in the Mediterranean Sea, primarily because of their biodiversity. Information on the spatial and temporal variability of the composition and structure of coralligenous assemblages is essential for the management and conservation of these unique biogenic habitat.