Variação sazonal dos grupos funcionais fitoplanctônicos em braços de um reservatório tropical de usos múltiplos no estado de São Paulo (Brasil)

Abstract

A análise dos grupos funcionais fitoplanctônicos em sistemas aquáticos pode oferecer subsídios à conciliação dos usos múltiplos. Essa pesquisa investigou a variação sazonal desses grupos no reservatório de Itupararanga (SP). Quatro braços foram amostrados para determinação de temperatura da água, pH, Radiação Solar Fotossinteticamente Ativa Subaquática (RSFA), turbidez, fósforo total, nitrato e sólidos suspensos totais (SST), além da contagem e identificação do fitoplâncton e análise de dados meteorológicos. O estudo, realizado em agosto e outubro de 2009 e fevereiro de 2010, sugeriu variação sazonal dos grupos fitoplanctônicos (p*<0,05), com predominância de organismos Sn, X1, M e F (inverno), X1, Y, F e K (primavera) e X1, J, K e W2 (verão). No inverno e na primavera, as principais variáveis que influenciaram a abundância dos grupos foram SST (7,4 a 48,1 mg L-1) e turbidez (7 a 96 UT). No verão, foram determinantes pH (7,7 a 9,8), temperatura (27,8 a 29, 1 ºC) e RSFA (>1.000 µE m-2 s-1). Em face à significativa variabilidade ambiental dos braços do reservatório, pela influência dos rios tributários, e à predominância de grupos fitoplanctônicos característicos de ambientes eutróficos, recomenda-se seu contínuo monitoramento para evitar prejuízos aos usos do sistema aquático, sobretudo para abastecimento e recreação.

Seasonal changes of water quality in a tropical shallow and eutrophic reservoir in the metropolitan region of Recife (Pernambuco-Brazil)

“…Positive correlation between pH and phytoplankton has also been found in studies of Dantas et al (2008) and Cunha and Calijuri (2011). The seasonal variation of pH can be explained by the increased consumption of CO 2 during the summer (Palma et al 2010).…”

“…Inverse relationships between transparency of water and biomass of phytoplankton have been reported (Moura et al 2007b, Chellapa et al 2009, Costa et al 2009, Cunha and Calijuri 2011. Some works indicate a dominance of P. agardhii in periods with less luminosity and higher turbidity (Chellapa et al 2009, Kokocinski et al 2010, 2012.…”

Diel dynamic of phytoplankton functional groups in a tropical water supply, Extremoz Lake, northeastern Brazil

“…In Brazil, studies on phytoplankton in short sampling intervals (24 hours cycle) have been carried out with his approach (Araújo et al, 2000;Barbosa, 2002;Melo and Huszar, 2000;Nabout and Nogueira, 2007;Becker et al, 2009;Barbosa et al, 2011;Cunha and Calijuri, 2011;Cruz, 2011;Dantas et al, 2009;Dantas et al, 2011). Natural coastal lagoons in Rio Grande do Norte systems are important, especially when using as water supply for the city of Natal, as in Extremoz Lake (Raposo and Gurgel, 2003).…”

Richness and distribution of aquatic macrophytes in a subtropical reservoir in São Paulo, Brazil

“…However, the low similarity suggests that the Itupararanga Reservoir is a heterogeneous ecosystem supporting the growth of different species contributing to biological diversity. Despite the low spatial variation of the physical and chemical variables, some recent studies (Cunha & Calijuri, 2011b;Bottino et al, 2013) reported that the main factors related to the spatial heterogeneity of ) at different sampling sites of the Itupararanga Reservoir in two seasons (summer and winter) in 2010. There were no measurements in the sampling sites with absence of macrophytes (in the winter P6, P7 and P9).…”

“…Considering that an increase in nutrients is common during this period in the study area (Cunha & Calijuri, 2011b) and that the electrical conductivity may be considered an indirect measure of the concentrations of nutrients dissolved in the water (Cometti et al, 2008), an increase in this variable in the winter allowed us to suppose that the trophic status influenced the biomass of E. crassipes in the winter.…”