A comparative study of cyanobacterial diversity in polluted and unpolluted microbial mats by means CLSM

This paper is a summary of the results obtained front a study of the diversity of cyanobacteria in oil Polluted and unpolluted natural environments. Our work group identified the different genera of cyanobacteria by means of CLSM, as this technique is specifically appropriate for Studying the diversity of these microorganisms in stratified bentonic environments (microbial mats). The cyanobacteria identified in pristine ecosystems show that the most abundant cyanobacteria correspond to the genera: Microco"s chthonoplastes, Oscillatoria sp., Lyngbya sp., Leptolyngl,a sp., and Limnothrix sp. Phormidium sp.and Pseudanabaena sp. were also identified, although they were less abundant. On the other hand, in the ecosystems heavily polluted with oil (Etang de Berre) neither Microcoleus chthonoplastes nor Oscillatoria sp. were detected, although the other genera mentioned were. With respect to coccoid cyanobacteria, the most abundant groups in the Ebro delta were Gloeocapsa sp. and Synechocystis sp. and also the genus Chroococcus sp. with Synechocystis sp. dominating the mats from Saline de Giraud. The microbial mats from Orkney Islands showed a different composition from those above (Pleurocapsa-group and Microcystis sp., Aphanothece sp. and Merismopedia sp.)