Abstract The influence of environmental variables on planktonic biodiversity is widely known. However, the absence of information about the cyanobacterial community in tropical estuarine regions motivated this work, whose objective was to investigate the spatio-temporal variation of cyanobacterial density related to physicochemical factors in a Brazilian Amazonian estuary. For the qualitative and quantitative study of cyanobacteria and physicochemical variables, samples were collected in April/July/2009 and April/August/2010. We identified 31 species of the orders Chroococcales, Oscillatoriales and Nostocales. Species of the genera Aphanocapsa, Dolichospermum, Komvophoron, Microcystis, Pseudanabaena and Merismopedia were frequent and abundant throughout the study period. Some of the found genera have already been described as potential toxin producers. The dynamics of cyanobacteria were temporal, the highest densities occurred in 2010 (average= 1080.86 ± 702.86 cells.mL-1) mainly influenced by the high values of pH, temperature, electrical conductivity, total dissolved solids, ammonium nitrogen which led cyanobacteria to present different responses in terms of richness, density and diversity between the years.

Due to the economic potential of camu-camu, considering its high concentration of vitamin C, the aim of this work was to evaluate the quality and genetic variability seven accessions of camu-camu conserved in genebank (BAG) of Embrapa Amazônia Oriental, in the state of Pará, Amazon region, Brazil. The fruits of camucamuzeiro were analyzed for physicochemical characterization (standard methodologies) and mineral composition. The data were subjected to multivariate statistical analysis, using the techniques of cluster analysis and principal component analysis. The formation of different groups for each genotype, which shows the genetic variability and the dissimilarity of the genotypes in the species data, may be used to guide the selection of promising genotypes to enrich the programs of genetic improvement of the camucamuzeiro. Ascorbic acid showed levels above 1000 mg 100 g-1, however, genotypes 4, 1 and 2 show the highest potential and the most promising nutritional capacity, but genotype 4 showed good characteristics for the moisture, acidity, carbohydrates, Cu and Zn and differs totally from others about the total soluble solids (TSS) and flavon-3-ol, features that make it the most promising genotype. It was possible to separate the seven different genotypes using multivariate analysis (hierarchical cluster analysis-HCA and principal component analysis-PCA).