SEX-PHEROMONES IN MARINE POLYCHAETES - VOLATILE ORGANIC-SUBSTANCES (VOS) ISOLATED FROM ARENICOLA-MARINA

Volatile organic substances (VOS) were extracted from the coelomic flu id of gravid specimens of the lugworm Arenicola marina through the use of using a closed loop stripping technique and analysed via coupled g as chromatography-mass spectroscopy. VOS detectable in coelomic fluid of mature specimens include aldehydes, n-alkanes, methyl-alkanes, terp enes and ketones. The bouquet of compounds is very similar to nereid v olatiles that have been recently described as having sex pheromonal ac tivity. One of the major constituents is the ketone 5-methyl-3-heptano ne, the sex pheromone of Platynereis dumerilii and Nereis succinea. Be havioural bioassays with gravid specimens produced no evidence that th is substance has any pheromonal function in A. marina. Samples taken a t monthly intervals showed an increase in the content of VOS in the co elomic fluid of both sexes during maturation with 1 major peak, 2-ethy l-hexanol, representing up to 50 % of the total amount of VOS in spawn ing male lugworms. Behavioural assays with ripe females established th e existence of a chemical cue inducing the burrow irrigation behaviour during which sea water is pumped through the burrows. This behaviour ensures transport of spermatozoa from the water column into the tube i nhabited by the female and increases fertilization success by minimisi ng the dilution effects of the incoming tide. The VOS extract obtained from male spawning water had biological activity in eliciting the 'pu mping' behaviour in females, with 16 of 24 worms irrigating continuous ly upon exposure, whilst controls showed no increase of activity, with 'pumping' occurring at 30 to 40 min intervals.