Algas fitoplanctônicas na Lagoa Juparanã (Linhares-ES): variação espacial, temporal e bioindicadores do estado trófico

• Ano de defesa: 2005
• Autor(a) principal: Gonçalves, Monica Amorim
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal do Espírito Santo; BR; Mestrado em Biologia Vegetal; UFES; Programa de Pós-Graduação em Biologia Vegetal
• Palavras-chave em Português: Biologia de água doce; Ecologia das lagoas; Fitoplancto de água doce; Lagoas; Limnologia; Juparanã, Lagoa (ES); Agronomia; 57
• Link de acesso: http://repositorio.ufes.br/handle/10/4380

The present work was done at Juparanã lake –Brazil’s larger lake in fresh water volume –located in Linhares-ES. There were four collections with quarterly periodicity along an annual cycle (season drought and rainy), in two sampling stations: point 1, situated in central point (in the middle of the lake) and, because of this, more natural considered and less impact and point 2 , located in the outlet river Pequeno, that connects the lake to the river Doce. Characterist limnological like, temperature, dissolved oxygen, pH, water electric conductivity, depth, main nutrients concentration, transparency were determined. The phytoplankton community was analysed in qualitative and quantitative terms, being made thecounting by the sedimentation method, besides the chlorophyll a determination.The obtained results showed that the lake can be characterized for pH with tendency to the neutrality (6,5), low electric conductivity (84,8 µS/cm), low turbidity (12,1 UNT) and nutrients poverty (PO43 -34,0 µg/L; NO3-118,6 µg/L; P-total 42,2 µg/L; NH4+48,9 µg/L; NO2-4,5 µg/L; N-total 550,7 µg/L), water transparency was high in the two first samplings, but it decreased considerably in the next samplings due to the rainfall season, the dissolved oxygen contents were elevated during the whole study and wasn’t verified thermal profile stratification most of the time. Phytoplankton community showed 109 algaes taxa, belonging to 9 algaes classes with low numerical density (794 ind./ml) and biomass algal numbers (1,4 µg/L of chlorophyll a). Cyanophyceae, Zygnemaphyceae and Chlorophyceae was dominant numerically. Zygnemaphyceae were represented mostly for algaes of family Desmidiaceae, described in the literature like bioindicators of oligotrophic waters. The most representative gender regardind taxa number was Staurastrum. Chlorophyceae represented mostly by Chlorococcales, and Eutetramorus/Radiococcuswas abundant in 50% of the quantitative samples. Regarding to Cyanophyceae although low density, Synechocystissp. was dominant in 22,7% of the samples and abundant in 54,5%. The Simple and Compound Nygaard Coefficient classifies as an mesotrophic to eutrophic ambient, however this index works with big taxa groups was not considered satisfactory in bioindicators studies. In point 2 were found filamentous species that usually are part of periphyton, very developed in this location. There wasn’t observed standards in phytoplankton vertical and temporal distribution. The low concentrations of nutrients and low levels of biomass and phytoplankton density points to oligotrophic conditions for the Juparanã lake and suggests to possible competitive relations between phytoplankton, periphyton and aquatic plants, mostly in point 2.Qualitative and quantitative analysis demonstrate Cyanobacteria's several taxa,with dominanceof Synechocystissp., what is an alertfor the pond uses, due to the toxins production potentiality.