Effects of fenvalerate on biochemical parameters, survival, and reproduction of Daphnia magna.

Daphnia magna were exposed to fenvalerate at nominal concentrations of 0.5, 0.25, 0.13, 0.06, and 0.03 micrograms/liter for 21 days. On Days 7 and 21 of exposure, levels of ribonucleic acid (RNA), deoxyribonucleic acid (DNA), adenosine diphosphate (ADP), adenosine triphosphate (ATP), glycogen, and lipid were measured, and the results were related to survival and reproduction during the 21-day test period. Survival was not significantly (alpha = 0.05) affected by the 21-day exposure; however, reproduction was reduced at fenvalerate concentrations of 0.25 and 0.5 micrograms/liter. On Day 7, protein, RNA, ADP, caloric equivalents, and glycogen were also significantly reduced at fenvalerate concentrations of 0.25 and 0.5 micrograms/liter. Thus, these biochemical parameters identified the same no observable effect concentration (NOEC) as did reproduction. Variables derived from biochemical parameters were related to reduced protein growth and reproduction. Decreases in protein/RNA and glycogen/lipid ratios and increases in ADP/DNA, ADP/ATP, protein/RNA/DNA, and lipid/DNA ratios were observed at Day 7 for those daphnia exposed to 0.5 micrograms/liter of fenvalerate. The only derived variable that reflected the reduced protein growth at Day 7 in daphnia exposed to 0.25 micrograms/liter of fenvalerate was the glycogen/lipid ratio. Biochemical determinations at Day 21 indicated that the organisms exposed to 0.25 micrograms/liter of fenvalerate were not different from controls, whereas those exposed to 0.5 micrograms/liter were still affected.