Biodiversity in Enclosed and Semi-Enclosed Seas -- Biodiversity issues for the forthcoming tropical Mediterranean Sea -- Biodiversity in the Black Sea: effects of climate and anthropogenic factors -- Measuring change of Mediterranean coastal biodiversity: diachronic mapping of the meadow of the seagrass Cymodocea nodosa (Ucria) Ascherson in the Gulf of Tigullio (Ligurian Sea, NW Mediterranean) -- Biodiversity evaluation of the macroalgal flora of the Gulf of Trieste (Northern Adriatic Sea) using taxonomic distinctness indices -- Biodiversity of settled material in a sediment trap in the Gulf of Trieste (northern Adriatic Sea) -- Phylogeography of the sea urchin Paracentrotus lividus (Lamarck) (Echinodermata:Echinoidea): first insights from the South Tyrrhenian Sea -- Community structure of the macroinfauna inhabiting tidal flats characterized by the presence of different species of burrowing bivalves in Southern Chile -- Response of zoobenthic communities to changing eutrophication in the northern Baltic Sea -- Diversity of juvenile fish assemblages in the pelagic waters of Lebanon (eastern Mediterranean) -- Stability of spatial pattern of fish species diversity in the Strait of Sicily (central Mediterranean) -- Recurrent high-biomass blooms of Alexandrium taylorii (Dinophyceae), a HAB species expanding in the Mediterranean -- Lack of epifaunal response to the application of salt for managing the noxious green alga Caulerpa taxifolia in a coastal lake -- Artificial Habitats and the Restoration of Degraded Systems -- Artificial habitats and the restoration of degraded marine ecosystems and fisheries -- Fish assemblages on sunken vessels and natural reefs in southeast Florida, USA -- Effect of depth and reef structure on early macrobenthic communities of the Algarve artificial reefs (southern Portugal) -- Stakeholder perceptions regarding the environmental and socio-economic impacts of the Algarve artificial reefs -- History, ecology and trends for artificial reefs of the Ligurian sea, Italy -- Settlement and early survival of red coral on artificial substrates in different geographic areas: some clues for demography and restoration -- A fourteen-year overview of the fish assemblages and yield of the two oldest Algarve artificial reefs (southern Portugal) -- Long-term changes in a benthic assemblage associated with artificial reefs -- Development of a transplantation technique of Cystoseira amentacea var. stricta and Cystoseira compressa -- Gametogenesis and maturity stages scale of Raja asterias Delaroche, 1809 (Chondrichthyes, Raijdae) from the South Ligurian Sea -- Feeding strategy of the sacoglossan opisthobranch Oxynoe olivacea on the tropical green alga Caulerpa taxifolia -- Species-specific probe, based on 18S rDNA sequence, could be used for identification of the mucilage producer microalga Gonyaulax fragilis (Dinophyta) -- Assemblages in a submarine canyon: influence of depth and time. The main themes of the Symposium were biodiversity in enclosed and semi-enclosed seas and artificial habitats, and the restoration of degraded systems. These themes are highly relevant today both from a basic scientific point of view and from an applied approach. The papers dealing with the first theme represent current research and concerns about marine biodiversity in enclosed seas and will have wide appeal to all those interested in understanding and preserving the biodiversity of the seas and in particular of the Mediterranean and Black Seas. The papers in the second theme represent a synthesis of up-to-date knowledge on artificial habitats and how they can contribute to protection of coastal marine ecosystems, to enhancement of species diversity and biological resources and to restoration of degraded marine environments.