Effects of the volatile fraction of crude oil on spawning behaviour of nereids (Annelida, Polychaeta)

Volatile organic substances (VOS) in the volatility range inclusive of n-nonane and n-dodecane were derived by fractionated distillation from crude oil (EKO-FISK, North Sea) and their effects examined on two polychaete species, Platynereis dumerilii and Nereis succinea. In behavioural bioassays, ripe male heteronereids of both species were induced to perform their characteristic spawning behaviour. Male heteronereids which had been swimming at the water surface searching for the females were induced to swim in narrow circles when 0.3 ppm VOS fractions were added. This nuptial dance results in the release of gametes into the free water without contact with females. In contrast, no behavioural effect was observed in females.