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Microvegetation on the top of Mt. Roraima, Venezuela.

2011; Česká algologická společnost; Volume: 11; Issue: 1 Linguagem: Inglês

10.5507/fot.2011.017

1805-4927

Jan Kaštovský, Karolina Fučíková, Tomáš Hauer, Markéta Bohunická,

Biocrusts and Microbial Ecology

Venezuelan Table Mountains (tepuis) are among world's most unique ecological systems and have been shown to have high incidence of endemics.The top of Roraima, the highest Venezuelan tepui, represents an isolated enclave of species without any contact with the surrounding landscape.Daily precipitation enables algae and cyanobacteria to cover the otherwise bare substrate surfaces on the summit in form of a black biofilm.In the present study, 139 samples collected over 4 years from various biotopes (vertical and horizontal moist rock walls, small rock pools, peat bogs, and small streams and waterfalls) were collected and examined for algal diversity and species composition.A very diverse algal flora was recognized in the habitats of the top of Mt.Roraima; 96 Bacillariophyceae, 44 Cyanobacteria including two species new to science, 37 Desmidiales, 5 Zygnematales, 6 Chlorophyta, 1 Klebsormidiales, 1 Rhodophyta, 1 Dinophyta, and 1 Euglenophyta were identified.Crucial part of the total biomass consisted of Cyanobacteria; other significantly represented groups were Zygnematales and Desmidiales.Investigated biotope types were demonstrated to have different composition of algal communities.