Reduction of recruitment of Acartia pacifica nauplii from benthic resting eggs due to organochlorine pesticides

Many estuarine and coastal planktonic copepods depend on the hatching of benthic resting eggs for recruitment of nauplii to the water column populatio n. The potential effects of two organochlorine pesticides, hexchloriobinzene (HC H) and dichlorodiphenyltrichloroethane (DDT), on the recruitment of Acartia paci fica nauplii from benthic resting eggs in the seabed of Xiamen Bay were experime ntally investigated. The abundance of A. pacifica nauplii hatched from the sedim ent significantly decreased with the increase of pesticide concentration. Trimme d Spearman-Karber analysis gave sediment 96-h LC50 values were 84.81 ng/g for HC H, and 157.94 ng/g for DDT. The median AI (AI50) was -0.77, which suggested that the combined effect of HCH and DDT showed a weak effect than individual effects . There was a positive relationship between mortality and exposure time in DDT t reatment, while the relationship was not significant in HCH treatment. The resul ts suggest that organochlorine pesticides can reduce recruitment of A. pacifica nauplii from benthic resting eggs to planktonic population.