Phytoplankton flora of two rivers in Southeast Brazil: Paraibuna and Pomba Rivers, Minas Gerais

Abstract

-(Phytoplankton flora of two rivers in Southeast Brazil-Paraibuna and Pomba Rivers, Minas Gerais). This work is a survey of the phytoplankton communities of the Paraibuna and Pomba Rivers. It aims is to contribute to the existing albeit scarce knowledge of the phytoplankton of Minas Gerais and of lotic phytoplankton in general. The results are based on 32 samples collected from Paraibuna and Pomba Rivers, in Minas Gerais State, during the dry (July and August, 2001) and rainy seasons (February 2002). Forty-eight taxa were identified, 20 from Paraibuna River and 28 from Pomba River, thirty-eight of which are new records for Minas Gerais State. The phytoplankton community of Paraibuna River was strongly influenced by a reservoir close to its source, thus the occurrence of lentic species of cyanobacteria and desmids. However, the phytoplankton community of Pomba River was typical of lotic environments, with great number of diatoms and desmids. Key words-potamoplankton, taxonomy, tropical rivers RESUMO-(Flora fitoplanctônica de dois rios no Sudeste do Brasil-Rios Paraibuna e Pomba, Minas Gerais). É apresentada a composição fitoplanctônica dos Rios Paraibuna e Pomba, contribuindo para o escasso conhecimento do fitoplâncton de ambientes lóticos e também do Estado de Minas Gerais. Os resultados são baseados em 32 amostras coletadas nos Rios Paraibuna e Pomba, em Minas Gerais, durante a estação seca (agosto, julho/2001) e chuvosa (fevereiro/2002). Foram identificados 48 táxons, sendo 20 no Rio Paraibuna e 28 no Rio Pomba. Destes, 38 são primeira citação para o Estado de Minas Gerais. O fitoplâncton do Rio Paraibuna foi influenciado pela presença de um reservatório, favorecendo a ocorrência de cianobactérias de ambientes lênticos juntamente com desmídias. A composição do Rio Pomba foi tipicamente de ambientes lóticos, com maior número de diatomáceas e desmídias. Palavras-chave-potamoplâncton, rios tropicais, taxonomia

Phytoplankton of two rivers in the eastern Amazon: characterization of biodiversity and new occurrences

“…In addition, water velocity tends to decrease during the dry season (Nogueira 2000;Zeng et al 2006;Cunha et al 2013). The occurrence of a larger number of taxa during the dry season has also been reported for other Brazilian rivers, such as the Urubuí (Aprile & Mera 2007), Paraibuna and Pomba (Soares et al 2007).…”

“…This result was expected, because diatoms are typical of predominantly lotic environments (Soares et al 2007). These organisms did not exhibit the highest richness, but they occurred in almost all samples.…”

“…In fact, the water retention time might increase considerably. On rivers with dams, such as the Paraibuna river (in the state of Minas Gerais) and the Paranapaíba river (in the states of Goiás and Minas Gerais), Cyanophyta is the most well-represented division, in terms of the number of species (Soares et al 2007;Oliveira et al 2011). The increase in species richness seen during the dry season in the present study might be related to the physical characteristics of that season, such as greater solar radiation, higher temperatures and less precipitation, all of which favor the growth of algae (Kivrak 2006;Marques et al 2012).…”

“…Knowledge of the biodiversity of these algae is, however, quite heterogeneous regarding geographic region, taxonomic group (Bicudo & Menezes 2010) and type of aquatic ecosystem (Soares et al 2007).…”

“…The phytoplankton biodiversity in the rivers of Brazil is still poorly studied, despite the extensive river system in the country (Soares et al 2007). This is attributable, in part, to the high cost and complex logistics of conducting research on rivers in comparison with those of studies carried out in discrete environments (small lakes and reservoirs), features that Bozelli & Huszar (2003) referred to as "methodological difficulties".…”