Ref ID : 1667
A. Fernandez-Casalderrey, M.D. Ferrando, and E. Andreu-Moliner; Chronic toxicity of methylparathion to the rotifer Brachionus calyciflorus fed on Nannochloris oculata and Chlorella pyrenoidosa. Hydrobiologia 255/256:41-49, 1993
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The effect of sublethal levels of methylparathion (0, 1, 3, 5, 7 mg l-1) on the freshwater rotifer, Brachionus calyciflorus, during their entire life cycle was studied. Rotifers were fed on two species of unicellular algae: Nannochloris oculata and Chlorella pyrenoidosa; both algal concentrations were 5x10E5 cell ml-1. The parameters used to determine the toxicity of this compound were survival, fecundity, net reproductive rate (Ro), generation time (T), intrinsic rate of natural increase (r), reproductive value (Vx/Vo) and life expectancy at hatching (eo). All the demographic parameters studied were affected by methylparathion exposure on rotifers fed on both species of algae, but the toxic effect was larger when animals were fed on Chlorella pyrenoidosa; in this case, animals showed a decreased in fertility and also a delayed first reproduction. Sublethal methylparathion levels produced a reduction in most of the parameters selected, especially after exposure to 7 mg l-1, where the animals died before reproducing.