The early establishment and development of a polychaete community settled on artificial substrata at Todos Santos Bay, Baja California, Mexico

The polychaete colonization process was studied in Todos Santos Bay, Baja California, by suspending 39 plates in April 1997 and recovering replicates at 14–45 d intervals over a year. A total of 3579 polychaetes representing 13 families and 38 species was collected during this period. Composition and structure of the community were studied. A 'lag-period of 48 d was observed before settlement of polychaetes. First macrofauna colonizers were barnacles (Balanus amphitrite) and amphipods (Caprella californica, Corophium sp., Erithonius brasiliensis). The best represented polychaete families were: Serpulidae (59.5%), Spionidae (11.1%) and Opheliidae (8%). The main trophic groups were filter-feeders (59.8%) and deposit-feeders (27.6%). The early stages were dominated by species belonging to the Nereididae and Serpulidae, whereas the last 3 mo were dominated by the Polynoidae, Phyllodocidae, Terebellidae, Syllidae, Opheliidae, and Serpulidae. Abundance, number of species, and diversity increased progressively, with a peak of 292 polychaetes, 23 species per plate and, 3.914 bits ind ⁻¹ on the last plates collected after 378 d of immersion. Czekanowski and Jaccard's coefficients separated five groups of plates, depending on their 'immersion age', and six groups of species in relation to their abundance and the period in which they were present. The multivariate analysis (FCA) revealed the existence of a colonization pattern linking an opportunistic/pioneer community to a more mature and organized community, there was a separation between the first and second half of the study, in which abundance, number of species, diversity, equitability, and dominance presented different values.