Reproductive output of a meiobenthic copepod exposed to sediment-associated fenvalerate

The benthic harpacticoid copepod, Amphiascus tenuiremis, was cultured through one generation at four concentrations (600, 300, 150, and 0 micrograms/kg) of sediment-associated fenvalerate, a synthetic pyrethroid insecticide, to assess effects on reproductive output and age structure. Two static renewal experiments with four replicates of each treatment were conducted. At the end of 21 days, surviving copepods were sorted and counted into adult males, adult females, copepodites, and nauplii. Fenvalerate was extracted from the sediment and measured by GC-MS. The number of individuals in each life-history stage in fenvalerate treatments was not significantly different from controls, except for increased adult females in fenvalerate in the second experiment. The overall lack of a fenvalerate toxic effect on A. tenuiremis was most likely because fenvalerate tightly binds to sediments and was probably not bioavailable to the copepods. Sediment-associated pesticides with large octanol:water partitioning coefficients (K(ow)'s) such as fenvalerate appear to be less toxic to infaunal copepods than those exhibiting smaller K(ow)'s.