PARENT SESSION
HA8 Cyanobacterial toxins: health and environmental hazards
9:00 AM to 1:30 PM, Thursday, 10 May 2001
Session Chair: V. Vasconcelos
Room 8

(474) Dynamics and toxicity of Anabaena waterblooms in Oued Mellah hypertrophic lake (Morocco).

Brahim, Sabour^1,2, Mohammed, Loudiki², Brahim, Oudra², Said, Oubraim³, Brahim, Fawzi³, Souad, Fadlaoui³, Vitor, Vasconcelos⁴, ^{1 2 3 4}

ABSTRACT- In the present work, the structure and abundance of phytoplankton communities were investigated in Oued Mellah, an hypertrophic lake, in 1997-1999 period. Important development of cyanobacterial blooms were observed mostly due to Microcystis ichthyoblabe and Anabaena sp.. Anabaena blooms proliferate during late summer succeeding to M. ichthyoblabe blooms. The Anabaena maximum percentages in the total phytoplankton biomass varied from 88 to 94% during bloom periods with maximal biomass of 146 and 120 mg/L respectively in summers 1997 and 1999. The dynamics of phytoplankton communities, especially of Anabaena blooms, in relation to some physical and chemical water properties as well as results on toxicity of both natural bloom and isolated strains evaluated by mouse and Artemia bioassays, Enzyme-linked immunosorbent assay (ELISA) and high performance liquid chromatography with photodiode array (HPLC-PDA) techniques will be presented and discussed.

Key words: Cyanobacteria, Anabaena, Ecology, Toxicity