Toxins 2010, 2, 1019-1037; doi:10.3390/toxins2051019 OPEN ACCESS toxins ISSN 2072-6651 www.mdpi.com/journal/toxins Review A Review on Toxic and Harmful Algae in Greek Coastal Waters (E. Mediterranean Sea) Lydia Ignatiades 1,* and Olympia Gotsis-Skretas 2 1 National Center of Scientific Research ―Demokritos‖, Institute of Biology, Aghia Paraskevi, 15310 Athens, Greece 2 Hellenic Center for Marine Research, Institute of Oceanography, 19013 Anavyssos, Greece; E-Mail:
[email protected] * Author to whom correspondence should be addressed; E-Mail:
[email protected]; Tel.: +30 210 6503629; Fax: +30 210 6511767. Received: 22 March 2010; in revised form: 23 April 2010 / Accepted: 5 May 2010 / Published: 11 May 2010 Abstract: The Greek coastal waters are subjected to harmful algal bloom (HAB) phenomena due to the occurrence of species characterized as toxic (TX), potentially toxic (PT), and non-toxic, high biomass (HB) producers causing harm at multiple levels. The total number of (TX), (PT) and (HB) algae reported in this work are 61, but only 16 species have been associated with the occurrence of important HABs causing damage in the marine biota and the water quality. These phenomena are sporadic in time, space and recurrence of the causative species, and are related to the anthropogenically-induced eutrophication conditions prevailing in the investigated areas. Keywords: harmful algae; Aegean Sea; Ionian Sea 1. Introduction The coastline (18,000 km) of the Greek mainland is located in the Eastern Mediterranean Sea, it is surrounded by the Aegean, Ionian and Cretan Seas and its morphological regime shows a variety of gulfs and semi-enclosed gulfs.