Rhodolith beds in the Mediterranean (A5.51)

Rhodolith beds are formed by the accumulation of various species of unattached red calcareous algae (Rhodophyta). They are composed of living and dead thalli, and although they have a patchy distribution, they occur throughout the Mediterranean Sea where they are particularly abundant. Mediterranean rhodolith beds are known to be hot-spots of biodiversity, hosting a high diverse invertebrate community. Moreover, they are amongst the Mediterranean communities with the highest amounts and production rates of carbonates, and they provide nursery grounds for commercial fish and shellfish species. Commercial dredging, trawling fisheries, chemical pollution by organic matter and excess nutrients are the major threats identified for these habitats. Rhodolith-forming algae are likely to be also affected by the ongoing global warming and ocean acidification. The need to grant protection to the characteristic species of this Mediterranean assemblage should also be considered along with a moratoria on the issue of further permits for the siting of aquaculture units above rhodolith grounds; monitoring programmes: designation of ‘no-take’ reserves and MPAs where these habitats occur; and establishing measures to limit the impacts that might affect water quality above rhodolith beds.