Interference Tests with the Pheromone System of the Brown Alga Cutleria multifida

Abstract

Male gametes of the brown alga Cutleria multifida (Smith) Grev. are attracted to sources which release the sex pheromone multifidene into seawater. In interference tests the effect of additional pheromone or an analogue was studied. The threshold concentration significantly affecting gametes varies around 60 ng of multifidene 1-l. Crude oils interfered with the chemotactic response at concentrations between 1 mg and 23 pg I-', lower concentrations were not tested. But petroleum hydrocarbons did not initiate the characteristic search pattern which male gametes normally display in the presence of multifidene. In contrast, extracts containing liquid hydrocarbons and similar compounds of low polarity from different seawater samples caused this characteristic response. This indicates an ubiquitous presence of pheromone-like compounds in the sea.