Reeve) during their early ontogeny. The bacteria in the phycospere on the surface of the attachment substance has a significant impact on the growth of the larvae. Up to now, little is known about the bacterial diversity in the phycospere on the adhering substance. We collected the attachment substance from seedling Reeve and analyzed the bacterial community diversity and variation in the phycospere by PCR-DGGE. The bacterial community structure in the phycospere changed over time. Although there was considerable similarity in the community between adjacent days (Dice coefficient C_s: 80.9%–96.1%) there was a significant difference between early stage and late stage seedlings. Analysis of the diversity index revealed an increase in the richness of the bacterial diversity of the phycospere in early stage seedlings, and diversity was maintained thereafter. The bacterial diversity index remained within a given range because of the influence of algae growth and abalone feeding activity. Our results provide a theoretical basis for scientific breeding and healthy aquaculture of abalone, and lay a foundation for further study of the relationship between environmental changes and bacterial diseases of larval abalone.