A comparative analysis of Alexandrium catenella/tamarense blooms in Annaba Bay (Algeria) and Thau lagoon (France); phosphorus limitation as a trigger.

Environmental conditions ultimately leading to blooms of the toxic dinoflagellate Alexandrium catenella/tamarense were investigated at two Mediterranean sites (Annaba Bay, Algeria and Thau lagoon, France). Three years were examined in details: 1992 (a pre-Alexandrium period), 2002 (a year with the first bloom in Annaba) and 2010 (a year with a major bloom in Annaba). Most conditions were similar, but ammonium concentrations were much higher in Annaba (up to 100μM) than in Thau (up to 10μM).