Meeting Abstract

56.3  Saturday, Jan. 5  Settlement and metamorphosis of the planulae of Pocillopora damicornis (Anthozoa) in response to bacteria TRAN, C.*; HADFIELD, M.G.; University of Hawaii at Manoa; University of Hawaii at Manoa cawa@hawaii.edu

Larvae of the scleractinian coral Pocillopora damicornis are induced to settle and metamorphose in the presence of marine biofilms. In this study, bacteria were isolated from various reef surfaces, including different species of coral and algae, and slides that had been placed in the field for 1-2 months to develop a coat of biofilm. Settlement assays were conducted on monospecific strains isolated from the field, as well as those isolated from laboratory sea tables. Inductive strains were not particularly associated with a certain type of surface from which the strain was isolated. Of the 56 isolates, 3 have shown strong inductive capacity, whereas the others were moderate to none. The isolates were identified by sequencing 16S rRNA and their phylogenetic relationships analyzed. One particular strain, Pseudoalteromonas luteoviolacea, which showed strong inductive capacity, was further tested in settlement assays of different bacterial densities, and results suggest there was an optimal density at which metamorphic induction occurs. In addition, comparison of larval swimming behavior on clean vs. multispecies-biofilmed surfaces revealed a distinct difference: larvae continue to swim over the clean surface, whereas they sink onto the biofilmed surface, suggesting the latter may be a more favorable substratum for larvae to settle and, therefore, metamorphose.