Cyanobacterial diversity in alkaline marshes of northern Belize (Central America)

Cyanobacterial mats are important ecosystem components of oligotrophic alkaline marshes of northern Belize. They initially develop as benthic communities forming thick carpets on the bottom and on submerged plant stems (mainly Eleocharis spp.), and later rise to the surface as floating mats. Rich diversity of cyanobacterial morphospecies was found in these communities, with dominating oscillatorialean (filamentous, non-heterocytous) types. However, the coccoid species were the most diversified, and few heterocytous types were present in larger amount in limited periods of mats seasonal development. The diversity was evaluated both by phenotype criteria and by the genetic analysis including complete sequence of the 16S rRNA gene and TGGE. According to the traditional taxonomy, 45 coccoid, 27 oscillatorialean and 15 heterocytous morphospecies were recognized, of which only less than 70% were identifiable according to the available literature, and about 60% of the described species have been known only from tropical regions. These conclusions proved that the cyanoprokaryotic microflora from these unique habitats is highly specialized, and contains numerous adapted forms for this habitat and possibly endemic in this region. The genotype diversity study confirmed the novelty of the endemic form found with the phenotype study. From the comparison with the other studied Central-American habitats it follows that similar specialized cyanobacterial assemblages are characteristic of alkaline marshes in the whole Caribbean district (Florida-Everglades, Puerto Rico, SW coastal regions of Cuba, Jamaica, islands off Venezuela, southern states of Mexico).