Influence of local and global environmental parameters on the composition of cyanobacterial mats in a tropical lagoon (Ebrié Lagoon, Ivory Coast)

Abstract

We evaluated phytoplankton abundance, composition and trophic state of the EbriA© Lagoon on the basis of data taken in the period of June 2006 to February 2007. Sampling was performed at 13 stations in lagoon. Among three identified Cyanobacteria orders, Oscillatoriales dominated the peuplement with 47.62%. The distribution of the Oscillatoriales orders shows a predominance of genera Oscillatoria mainly composed of Oscillatoria cf. leonardii, Oscillatoria princeps and Oscillatoria limosa. The Chroococcales and Nostoccales constitute about 28.57% and 23.81% respectively of the total taxa. The blooms of Cyanobacteria in the lagoon were contributed by seven species. Those are Cylindrospermopsis raciborskii, Anabaena flos-aquae, A. planctonica, Anabaena sp., Oscillatoria limosa, Lyngbya martensiana and Microcystis aeruginosa. Abundance and seasonality of Cyanobacteria observed, characterized the EbriA© Lagoon as a highly eutrophicated environment. The NO3−, SiRD and PRD, salinity regime and tranparency availability played important role in determining the distribution, diversity, and composition of Cyanobacteria communities.