Effects of cyanobacterium exopolysaccharides on life-history of Ceriodaphnia cornuta SARS

The objective of the present investigation was to verify ifAnabaena spiroides exopolysaccharides sustains growth and reproductionof Ceriodaphnia cornuta. The animals were raised in controlledlaboratory conditions and fed exclusively on A. spiroides exopolysaccharides,which were obtained from filtered stationary growth phase A.spiroides cultures. A molecular weight cut-off of 12–14kDa was used to separate the exopolysaccharides from low molecularweight materials. The lyophilized exopolysaccharides were dissolvedin filtered and autoclaved reservoir water at a concentrationof 15 mg L^–1 (0.22 ± 0.01 mg C animal^–1day^–1).These results were compared with animals fed on seston at naturalconcentration obtained by filtering (68 µm) Barra BonicaReservoir water (0.23 ± 0.01 mg C animal^–1day^–1).Several life history parameters (duration of embryonic development,generation time, reproductive performance, age-specific length,primipara age and length) were obtained during 15-day experiments.Growth rate (GR) and weight-specific secondary production werealso quantified. Exopolysaccharide-fed organisms had bettergrowth and reproductive performance (0.091 ± 0.004 GR;51 ± 4.59 eggs produced per female) than seston-fed individuals(0.078 ± 0.010 GR; 30.90 ± 7.25 eggs producedper female). These results show that such macromolecules area potential food source, fulfilling nutritional requirementsto sustain growth and reproduction of C. cornuta and supportstrophic relationships in aquatic ecosystems.