SHIKUMA, N. J.; HADFIELD, M. G. ; Univ. of Hawaii; Univ. of Hawaii: Revealing bacterial biofilm community composition and its role in inducing metamorphosis of the tubeworm Hydroides elegans

The succession of sessile biofouling invertebrates is known to occur around the world, however the mechanisms behind this phenomenon have yet to be explained. Specific cues for settlement and metamorphosis exist for many planktonic marine invertebrate larvae, and are often associated with a favorable environment such as conspecifics or resources. The serpulid polychaete Hydroides elegans is induced to settle and metamorphose in response to a bacterial biofilm, defined as an aggregation of bacteria and their extracellular matrices adhered to a surface. This tubeworm is the primary colonizer of newly submerged surfaces in the succession of organisms in tropical to subtropical estuaries and boat harbors. In this study, the density and species composition of biofilms from Pearl Harbor, Honolulu, are characterized over a given time period using Denaturing Gradient Gel Electrophoresis (DGGE) and correlated with rates of metamorphosis of H. elegans. DGGE revealed that a set of bacterial species is always present in biofilm communities over time, while other species appear or disappear at different time intervals. Densities of bacteria in a biofilm and its species composition are also shown to influence settlement of H. elegans, and may be one determinant of invertebrate succession on a macro-fouling level.