The coralligenous habitat represents one of the most important hotspots of Mediterranean biodiversity. However, along the Ionian coast of Sicily (Italy) the coralligenous macroalgal assemblages have always been poorly studied. The present study was carried out in the coralligenous habitat of the Marine Protected Area (MPA) Isole Ciclopi, located along the central-eastern coast of Sicily. Previously, only a few floristic studies, including some data on the coralligenous flora, were conducted within this MPA in the 1970s and 2001. Therefore, the present study aimed to gain an updated knowledge on the coralligenous flora and to compare the current data with data derived from the previous floristic studies, to observe if in the last 50 years environmental changes occurred and to monitor the effectiveness of the MPA in protecting this habitat. In particular, the coralligenous flora of the MPA was analyzed through remotely operated vehicles (ROV) surveys and destructive samples. ROV surveys allow us to observe that the coralligenous assemblages of the MPA are well-structured, especially regarding the encrusting Rhodophyta, which showed the highest percent cover among the main morphological groups/taxa. Through the sample analysis in the laboratory, a total of 92 taxa has been recorded. Comparing the floristic lists of the present research and the past studies, an increase of local biodiversity was highlighted. Nevertheless, an increment of Non-Indigenous Species (NIS), warm-water species, and Rhodophyta with wide ecological valence was also noted. The main causes of these variations in the coralligenous flora have been traced back to reduced water transparency, maybe due to sedimentation, and a rise in the seawater temperature. Therefore, although the coralligenous assemblages of the MPA Isole Ciclopi appear to be well-structured, future studies will be necessary to continue monitoring this habitat to evaluate whether the MPA is effective in safeguarding this hotspot of biodiversity.
Keywords: MPA Isole Ciclopi; Mediterranean Sea; coralligenous biocenosis; marine strategy directive; phytobenthic assemblages.