Abstract

In this investigation bacteriological analyses of the early developmental stages of Argopecten purpuratus were performed on scallops spawned in situ (hatchery), and in the laboratory under sterile conditions. The results confirmed the occurrence of vertical bacterial transmission. In spawning in the laboratory Pseudomonas, Moraxella and Vibrio were found as the predominant Genera. Subsequently, the effect of these strains on larval survival was tested. From a total of 21 bacterial strains tested the major inhibition of swimming larvae were produced by Vibrio (Strain M); Pseudomonas; (Strain I) and Moraxella (strains T y S), which caused 96.6%; 81.4%; 61.7% and 51.28% of settlement of the larvae to the bottom, respectively. In a broodstock conditioning experiment, the use of filtered seawater decreased the bacterial concentration in reproductive organs. The lowest total culturable bacteria and vibrios concentration was detected in organisms treated with filtered seawater (0.5 μm).