Effects of Surface Texture, Flow, and Dissolved Cues from Biofilms on Settlement and Attachment of Fouling Organisms to Marine Coatings

摘要

This study investigated the effects of natural and man-made coatings on the settlement and adhesion of larvae of fouling organisms onto surfaces in realistic water-flow conditions characteristic of harbors, where the colonization of ships by fouling organisms takes place. The objectives were as follows: (1) supply larvae for experiments from target species representing different phyla, swimming capabilities, and attachment mechanisms; (2) measure water velocity profiles and turbulence near submerged surfaces in harbors; (3) determine which target species have larvae that alter their locomotion in response to dissolved substances from surfaces; (4) assess the dispersal and dilution of dissolved cues released from surfaces in harbors using larval bioassays; (5) in laboratory simulations of small-scale flow near surfaces in harbors, quantify the effects of different coatings on the trajectories of and encounters with those surfaces by larvae of the target species; (6) measure effects of coatings (e.g., biofilms, fouling organisms, man-made coatings) on attachment strengths of larvae of the target species; (7) test the feasibility of using laser-Doppler velocimetry in a large wave/flume to determine stresses encountered by and probability of attachment of microscopic larvae settling on surfaces with different degrees of fouling or textures. The results showed that the flow along surfaces in Pearl Harbor, Hawaii, is oscillatory due to wind chop and ship wakes. Flume experiments showed that such oscillations altered the effects of surface rugosity on the shear stresses imposed on settling larvae. Larvae of biofouling tube worms and bryozoans change their behavior when they contact biofilmed surfaces from swimming in straight paths to circling and crawling. But they do not respond to dissolved chemicals from biofilmed surfaces. Newly settled larvae of tube worms, barnacles, bryozoans, and juvenile tube worms adhere more tightly to biofilmed surfaces than to clean ones.