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Data of Thesis


Author: Silvia Mattos Nascimento.

Title: An ecophysiological study of Synechocystis aquatilis f. salina: Ratio N / P and its relation to the growth and photosynthetic activity

Year: 1996.    Full text (in Portuguese)


Over a 3-year period (October 1990 to August 1993) cyanobacteria represented 60% of the density and 52% of the biomass of the phytoplankton community of Lagoa da Barra (Maricá-RJ, Brazil). It was also seen that the cyanobacterial biomass was negatively correlated with nitrate+nitrite concentrations and DINIP04, PONIPOP, N03ITP e TN/TP ratios. Synechocystis aquatilis f salina was the predominant species, representing 57% of the cyanobacterial density during the entire period of the study Based on this data, the species was cultivated under laboratory conditions in ASM-I medium and ASM-I 10 times diluted for ail nutrients (ASM-1I10) with the following NIP ratios, 3:1, 10:1 and 30:1. Growth rate, chlorophyll a, protein and carbohydrate intracellular concentrations, carbohydrate excretion and the photosynthetic activity were investigated. It was ascertained that the species is well adapted to a condition of nitrogen limitation, compared to the Redfield ratio. High chlorophyll a and protein concentrations as well as the highest photosynthetic rate were observed on cultures of ASM-I medium with low NIP ratio (3: I). Furthermore, the cultures in medium with the highest NIP ratio (30: I) showed that the species is not adapted to this condition. This study is a contribution to the knowledge of the strategies utilized by cyanobacteria, which gives them a competitive advantage under nitrogen limitation.