This book represents the collation of the Abstracts of the 39th European Marine Biology Symposium (EMBS), held in Genova (Italy) in 2004 and organized by Italian scientists of the Dip.Ter.Is Department of the University of Genova. The central theme of the 39th EMBS was: Biodiversity in enclosed seas, and artificial marine habitats. The book includes more than 350 abstracts, from authors and participants from all European countries.