Effects of sodium and potassium on life history parameters of freshwater cladoceran Pseudosida ramosa

In this study, we measured the life history parameters of the tropical cladoceran Pseudosida ramosa at sublethal concentrations of sodium and potassium. The results showed that salinity affected its maximum body length at a concentration of 249 mg L -1 of sodium. There was also an increase in the number of days taken by females to reach maturity at a concentration of 11 mg L -1 of potassium, a reduction in the number of neonates produced by primipara at concentrations ranging from 25 to 249 mg L -1 of sodium, reductions in the survival at concentrations of 249 mg L -1 of sodium and 11 mg L -1 of potassium and reductions in the number of total neonates hatched at concentrations ranging from 41 to 249 mg L -1 of sodium and from 3.6 to 11 mg L -1 of potassium. The concentrations of the both salts that affected the reproduction of P. ramosa were lower than those that affected other endpoints. Key words: life history , potassium, Pseudosida ramosa , saline stress, sodium.