Use of specific bacterial-microalgal biofilms for improving the larval settlement of Argopecten purpuratus (Lamarck, 1819) on three types of artificial spat-collecting materials

Abstract

In hatcheries of Argopecten purpuratus it is a common practice to harvest the larvae in collectors covered with a coat of microbial biofilm to promote larval settlement. The biofilm coating is obtained by immersion of the collectors for a few days in seawater prior to its use in a process called “pre-conditioning”. The present study was an attempt to evaluate the pre-conditioning process of exposing three different brands of imported and locally produced collector materials (“Netlon”) to biofilms formed by the bacterium Halomonas sp. and the diatom Amphora sp. The results showed the highest degree of settlement of larval scallops on mature biofilms (90+h), but there were no significant substrate Netlon-dependent differences. Tests with Chilean-produced Netlon seeded with varied concentrations of Halomonas sp./Amphora sp. promoted settlement of the larval scallops better than naturally deposited microbial films. Future research is required to determine more precisely what substances or physical characteristics of the biofilms are effective in inducing larval settlement.