HIGHLIGHTS Crassostrea oysters larvae patterns in estuarine environments. Larvae distribution patterns in Guaratuba Bay (Paraná State - Brazil).

The present work aimed to evaluate the contamination of Escherichia coli in the surface waters and oysters from two cultivations of Guaratuba Bay and to analyze the correlation patterns among the concentrations of E. coli in the waters and in the oysters with the local physical-chemical parameters. Samples were collected in the spring of 2007 and summer, autumn and winter of 2008 from two points of the bay (internal point and external point). From each cultivation and sampling period, 18 oysters were collected. The samples of surface water were collected for the measurement of physical-chemical parameters (pH, salinity, temperature, dissolved oxygen, seston, particulate organic matter) and quantification of E. coli. The surface water analyzed in the summer presented the largest most probable number of E. coli, (1,659.22 MPN.100 ml-1 and 958,55 MPN.100 ml-1 at external and internal points, respectively. The oysters from the internal point presented more E. coli, except in the winter sampling. The largest contamination was observed in the spring, at the internal point (979,78 MPN.g-1). The Principal Components Analysis showed direct correlation among the amount of E. coli in the oysters and in the surface water.

O crescimento de Spirulina máxima foi estudado em três condições de cultivo: 1) agitação manual com iluminação natural; 2) agitação manual com iluminação artificial e; 3) agitação constante feita por compressor de aquário e iluminação artificial. O maior crescimento foi observado nesta última condição, onde após 185 dias foram observados valores médios de densidade ótica de 3,7 enquanto, valores de 1,8 e 1,9 foram obtidos no primeiro e segundo experimento, respectivamente. Diferentemente do ocorrido com os outros tratamentos, não foi observado declínio no crescimento após 185 dias, o que foi atribuído ao fato de que, sob constante agitação os sais ficam suspensos e não cristalizam, fato que acarretaria diminuição da disponibilidade de nutrientes necessários ao crescimento. Também a agitação constante permite que todas as células recebam a mesma iluminação, promovendo fotossíntese e consequentemente um maior crescimento e coloração verde característica. Conclui-se que o emprego do compressor de aquário é não somente viável, mas recomendável, pois além de diminuir a mão de obra ainda se mostrou mais eficaz, melhorando o rendimento.

Growth of Spirulina maxima was studied in three types of culture conditions with four replicates each: 1) manual aeration with natural sunlight; 2) manual aeration with artificial light; and 3) constant aeration with an aquarium compressor and artificial light. After 185 days of incubation, growth declined in the first two treatments, while in the third treatment, higher growth was observed with average optical density of 3.7 against 1.8 and 1.9 in the first and second treatment, respectively. This was probably due to the fact that under constant aeration the salts were suspended avoiding the crystallization what could cause a decrease in the availability of the necessary nutrients for the growth. Also, the constant stirring allowed all the cells to receive the same amount of light promoting photosynthesis and consequently, a larger growth and characteristic green coloration. Culture with constant aeration under artificial light should be used for S. maxima cultivation because, besides reducing labor hours, it could be a more effective method for improving the economic income.