Influence of bacterial exopolymers and the adult extract of Balanus amphitrite and Cthamalus sp. on cyprid metamorphosis of Balanus amphitrite

Abstract

Settlement of barnacle, a major fouling organism is believed to be controlled to a great extent by substratum characteristics such as, presence of conspecific adults or "gregariousness" inducing factors. Exopolymers secreted by bacteria can also play a major role in the recruitment of larvae of fouling organisms, probably by providing inducing/inhibitory chemical cues. In this experiment, the influence of the extract of adult Balanus amphitrite and the expolymers of the bacteria colonising Balanus amphitrite in nature on the cyprid metamorphosis of B. amphitrite has been examined. The experiments were carried out in polystyrene multiwells. A similar set of experiments was also repeated with the extract of Cthamalus sp. which co-exists in the intertidal zone along with B. amphitrite. The results obtained indicate that the addition of exopolymers as well as adult extract promoted settlement of cyprids. The degree of inducement varied with various combinations of exopolymers of different bacterial strains with or without adult extract of both the species.