Anuário do Instituto de Geociências (May 2008)
Levantamento das Cianobactérias Psâmicas em Sedimentos Superficiais Marginais da Lagoa Azul, Arraial do Cabo, Rio de Janeiro.
Abstract
The coastal area of the Rio de Janeiro State presents a series of lagoons, dune fi elds and strand plains, which are the result of thepaleogeographical evolution during Neogene. The lagoa Azul is situated at 22o56’52”S and 42o04’62”W in the Arraial do Cabo, locatedabout 160 km far the city of Rio de Janeiro. It is a natural hypersaline coastal aquatic body which, parallel to Atlantic Ocean. The presentwork focused on the identifi cation of psammic cyanobacteria in the surface sediments of the lagoa Azul. The samples were obtained byusing plastic tubes and were later aconditiones in opaque plastic containers and conserved in a 4% solution of formaldehyde. With thematerial obtained, permanent slides were prepared so as to characterize them phycologically. Qualitative analysis showed the presenceof 14 species and the occurrence of the families Chroococcaceae Nägeli 1849 (5 sp.), Phormidiaceae Anagnostidis & Komárek 1988(4 sp.), Synechococcaceae Komárek & Anagnostidis 1995 (2 sp.), Nostocaceae Kützing 1843 (1 sp.), Oscillatoriaceae Gomont 1892(1 sp.) and Pseudanabaenaceae Anagnostidis & Komárek 1988 (1 sp.). The incidence of these species is also recorded in other lagoons(Araruama, Pernambuco, Pitanguinha and Vermelha) in the northeast of Rio de Janeiro coast, such as the frequency of cyanobacteriais justifi ed by the harsh environment, without predation, with high salinity, elevated temperature and low concentration of oxygen.
