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First results on Microcystis ichthyoblabe Kütz. toxic bloom in the hypertrophic Oued Mellah reservoir (Morocco)

Published online by Cambridge University Press:  15 March 2009

B. Sabour ,
M. Loudiki ,
B. Oudra ,
S. Oubraim ,
B. Fawzi ,
S. Fadlaoui ,
M. Chlaida  and
V. Vasconcelos
B. Sabour
Affiliation:
Faculté des Sciences et Techniques Mohammadia, Département de Biologie, Mohammadia, Maroc. E-mail : sabour.brahim@lycos.com Faculté des Sciences Semlalia, Département de Biologie, Laboratoire d'Algologie, B.P. 2390, 40000 Marrakech, Maroc
M. Loudiki
Affiliation:
Faculté des Sciences Semlalia, Département de Biologie, Laboratoire d'Algologie, B.P. 2390, 40000 Marrakech, Maroc
B. Oudra
Affiliation:
Faculté des Sciences Semlalia, Département de Biologie, Laboratoire d'Algologie, B.P. 2390, 40000 Marrakech, Maroc
S. Oubraim
Affiliation:
Faculté des Sciences Ben M'sik, B.P. 7955 Sidi Othmane, Département de Biologie, Laboratoire d'Ecologie et d'Environnement, Casablanca, Maroc
B. Fawzi
Affiliation:
Faculté des Sciences Ben M'sik, B.P. 7955 Sidi Othmane, Département de Biologie, Laboratoire d'Ecologie et d'Environnement, Casablanca, Maroc
S. Fadlaoui
Affiliation:
Faculté des Sciences Ben M'sik, B.P. 7955 Sidi Othmane, Département de Biologie, Laboratoire d'Ecologie et d'Environnement, Casablanca, Maroc
M. Chlaida
Affiliation:
Faculté des Sciences Ben M'sik, B.P. 7955 Sidi Othmane, Département de Biologie, Laboratoire d'Ecologie et d'Environnement, Casablanca, Maroc
V. Vasconcelos
Affiliation:
Faculdade de Ciências do Porto, Departamento de Zoologia e Antropologia, Lab. Ecotoxicologia, 4050 Porto and CECA-ICETA, Campus Agràrio de Vairão, 4480 Vila do Conde, Portugal
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Abstract

The Oued Mellah reservoir (33°30' N-07°20' W) is a shallow brackish lake located 25 km North of Casablanca. A study of the phytoplankton community of this lake shows that it is affected by potentially toxic blooms of Cyanobacteria and Haptophyceae. Microcystis ichthyoblabe (first time recorded from Morocco), Anabaena aphanizomenoides, Oscillatoria chlorina (Cyanobacteria) and Prymnesium parvum (Haptophyceae) constitute the dominant phytoplankton taxa. M. ichthyoblabe starts its growth in late spring. In 1999, it formed a spectacular bloom during May-June, invading the lake with a maximal biomass of 298 mgFW.L-1. This proliferation coincided with high temperatures, strong luminous intensity, alkaline pH and low to undetectable contents of nitrates and orthophosphates. The toxicity of the M. ichthyoblabe bloom material was first determined by mouse bioassay. Bloom material collected during the maximal development phase has an LD50 about 502 mgDW.Kg-1. Hepatotoxicity was confirmed by histopathological study. The total contents of microcystins determined by ELISA technique both for bloom material and the isolated strain are about 0.79 and 5.4 µg.gDW -1 respectively. Analysis by HPLC-PDA allows the detection of 11 variants of microcystins. The use of the microcystin-LR authentic sample showed the absence of this microcystin variant in the samples analysed.

Keywords

bloomsMicrocystis ichthyoblabemicrocystinsHPLC-PDAELISAMoroccobloomsMicrocystis ichthyoblabemicrocystinesHPLC-PDAELISAMaroc
Type
Research Article
Information
Annales de Limnologie - International Journal of Limnology , Volume 38 , Issue 1 , March 2002 , pp. 13 - 22
Copyright
© Université Paul Sabatier, 2002

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