MUELLER, C.T.*; PRIESNITZ, F.M.; BECKMANN, M.; Cardiff University, Cardiff, UK; Carl-v.-Ossietzky Univ, Oldenburg, Germany; Univ. of Wales, Aberystwyth, UK: Pheromonal communication in Nereids and the likely intervention by petroleum derived pollutants

Nereis succinea and Platynereis dumerilii (Annelida, Polychaeta) are broadcast spawners and reproduce semelparously. The co-ordination of the final events in reproduction, swarming and spawning, is achieved by well-characterized waterborne sex pheromones. Following an investigation into the effects of the water-soluble fraction of crude oil on the swarming behaviour of Nereids, the volatile fraction (C9 � C16) of EKO FISK crude oil was found to interfere with the pheromonal communication inducing release of gametes in male specimen at levels < 0.3 ppm. Subsequent bioassay-guided analysis of the oil using vacuum distillation, column chromatography, preparative GC and GC-MS analysis showed that C5-alkylated benzenes were most potent in inducing sperm release. After LC and GC separation n-butyl-4-methylbenzene and 1,4-diethyl-2-methylbenzene were found to induce release of gametes at concentrations ≥4 nM. Structure and activity of three tentatively identified active isomers (ethyl-4-propylbenzene, 1,2 diethyl-3-methylbenzene and 2,4-dimethyl-1-propylbenzene) were not completely confirmed. Oil fractions rich in higher boiling components showed a tendency to block pheromone reception or to narcotise and intoxicate animals. These effects were induced partly by naphtalenes at levels down to approx. 320 nM but were, in the original mixtures, modified or compensated by the presence of gamete release inducing alkylated benzenes. Other highly paralysing substances remained elusive. The detected activity thresholds for inducing release of gametes are lower than of those reported for natural pheromones (nereithione: 60 nM, uric acid: 600 nM) but higher than background levels of aromatic compounds of 0.05 nM and below.