Temporal variation of an initial marine biofilm community and its effects on larval settlement and metamorphosis of the tubeworm Hydroides elegans

Planktonic larvae of many sessile marine invertebrates settle and metamorphose preferentially on surfaces covered by bacterial biofilms. The polychaete tubeworm Hydroides elegans is induced to settle by biofilms and is the primary colonizer of newly submerged surfaces in the succession of macrofouling invertebrates in Pearl Harbor, Hawaii, USA. This study examines the succession of bacterial community composition and cell density of marine biofilms, and how temporal changes in biofilms affect settlement of H. elegans. Settlement assays of H. elegans were conducted on naturally formed biofilms of increasing age from Pearl Harbor. Denaturing gradient gel electrophoresis and epifluoresence microscopy were used to identify community composition and densities of bacterial cells in biofilms. Results of this study suggest that increasing densities of a stable community, rather than a shift in dominant species composition of biofilm bacteria, are probably responsible for the primary colonization of submerged surfaces by H. elegans in Pearl Harbor. However, the current data leave open the question of why larvae of other biofouling invertebrate species known to settle in response to biofilms recruit to surfaces only at later times. * Corresponding author: Kewalo Marine Laboratory University of Hawaii 41 Ahui Street Honolulu HI 96813 USA T 1 808 539 7319 F 1 808 599 4817 E [email protected] Kewalo Marine Laboratory, University of Hawaii, 41 Ahui Street, Honolulu HI 96813, USA