Akrotiri Peninsula, Perissa Rock, Santorini island, Aegean Sea, Mediterranean

Macroalgae and seagrass taxonomy-related counts; Habitat characterisation; Habitat extent; Bathymetry and Elevation; Seabed photography; Fish taxonomy-related counts; Fish biomass in water bodies

Following local community’ requests (divers and fishermen), a baseline study was performed to assess the ecological state of two candidate coastal sites of Santorini island as potential Marine Protected Areas. To establish the ecosystem’s state prior to protection, various samplings were performed by means of scuba and free diving during October 2012. The following parameters were assessed: the infralittoral fish communities’ composition and biomass, the infralittoral hard bottom benthic communities’ structure, composition and abundance, the sea urchins’ density and biomass, the fan mussel’s (Pinna nobilis) presence and size, the Posidonia oceanica meadows, the upper infralittoral algal communities’ composition, coverage and ecological status and the presence of benthic invertebrates of conservation and other interest. Some preliminary data on coastal bathymetry were also collected. Results revealed a low total fish biomass and an absence of large apex predators in the wider study area, indicating a depleted ecosystem due to overfishing. The alien herbivorous species Siganus luridus and S. rivulatus were found in large densities, accounting for the largest proportion of total fish biomass. Overgrazing effects were also detected through the abnormal structure and composition of the infralittoral algal communities, suggesting the herbivorous siganids as the main culprit. In terms of eutrophication and other direct anthropogenic effects, both the Akrotiri and the Perissa Rock areas were found to present healthy and stable conditions, as reflected by both the status of the P. oceanica meadows and the upper infralittoral vegetation.

Hellenic Centre for Marine Research, Institute of Oceanography
46.7 km Athinon-Souniou Av. P.O.Box 712
Anavyssos

19013
Greece