ReviewUnderestimated cyanobacterial diversity: trends and perspectives of research in tropical environments

Cyanobacteria are photo–oxygenic prokaryotes present in nearly all ecosystems, where they are important in global oxygen, carbon, and nitrogen cycles. They are often recognized as the harbingers of eutrophication in freshwater systems and are increasingly being noted as nuisance species in marine ecosystems such as coral reefs. In recent years, cyanobacteria have been intensely studied due to their toxicity, harmful bloom formation, and because their distribution and abundance are expected to increase with climate change. Nevertheless, for all of their importance, many gaps in our knowledge of cyanobacteria remain: the distribution, dispersal, and biogeography of these microorganisms are still not understood. Until 1994 little attention was paid to tropical cyanobacteria and their diversity, despite some harmful invasive species having their putative origins in tropical habitats. However, more practiced articulation and research has recently uncovered previously undescribed biodiversity, and in turn changed our knowledge of the evolutionary relationships within the Cyanobacteria. The purpose of this paper is to describe the challenges of working with the cyanobacteria and to review what we know of them from tropical habitats.