Urban secondary sewage: an alternative medium for the culture of Tetraselmis chuii (Prasinophyceae) and Dunaliella viridis (Chlorophyceae)

The effect of different concentrations (10, 20, 30 and 40%) of urban secondary sewage on the growth of Tetraselmis chuii (Prasinophyceae) and Dunaliella viridis (Chlorophyceae) was examined to verify the possibility of its use as an alternative culture medium for these species. Stocks and 700mL duplicate batch cultures were maintained under controlled laboratory conditions. 30% and 40% additions were the most efficient for the growth of both species. Statistical analysis of the adjusted growth (cell.mL-1) and biomass (µg chlorophyll-a.mL-1) curves performed using the Chi-square test (p<0.05) demonstrated significant differences between the nutritive medium f/2 and the 40% addition used for these two species. The results suggested that some of the concentrations tested here yielded satisfactory cell densities and growth rates when compared with other culture media (macroalgae, bovine and chicken manure extracts). Thus it could be used by semi intensive aquaculture systems.Foi estudado o efeito das diferentes concentrações de esgoto urbano secundário (10%, 20%, 30% e 40%) sobre o crescimento de Tetraselmis chuii (Prasinophyceae) e Dunaliellla viridis (Chlorophyceae) para verificar a possibilidade do seu uso como meio de cultura altenativo para estas espécies. Culturas stocks duplicatas de 700mL foram mantidas sob condições de laboratório controladas. As adições de 30% e 40% foram as mais eficientes para o crescimento de ambas as espécies. Análises estatísticas para o ajuste do crescimento (cel.mL-1) e curvas de biomassa (µg clorofila-a.mL-1) em relação ao tempo de cultura desenvolvidas usando Chi-square test (p