Invited Paper MB+BI-MoM1
Surfaces and Signals: Dissecting Surface Properties for Controlling the Settlement and Adhesion of Algae

Monday, October 15, 2007, 8:00 am, Room 609

All man-made structures in marine or freshwater environments suffer from the problem of ‘biofouling’- the unwanted growth of bacteria (as biofilms), algae (diatoms and seaweeds) and invertebrates (e.g. barnacles, tube-worms). Most current, commercial antifouling strategies use biocide-containing coatings, which are subject to increasingly stringent environmental restrictions. Alternative coating technologies that do not require biocides either invoke ‘deterrence’ to prevent organisms from sticking in the first place, or the ‘non-stick’ or ‘foul-release’ principle to facilitate the detachment of adhered organisms under moderate shear stress. The search for ‘environmentally-friendly’ solutions has stimulated basic research efforts in an attempt to understand which interfacial properties (e.g. roughness, wettability, charge, friction, elasticity) are important in influencing the adhesion of fouling organisms. This has been facilitated by the advent of novel technologies, such as various forms of lithography, and self-assembly, which enable the production of test surfaces with systematic variations in structure and properties at the micro- and nano-scales. Motile marine organisms such as spores of Ulva, are highly selective in their choice of a suitable surface for settlement. Therefore, one approach to developing practical coatings based upon ‘deterrence’ is to try to destabilize the surface cue-sensing mechanisms of the organism. The aim of this presentation is to illustrate how spores of the green alga Ulva, and the diatom, Navicula respond to surfaces presenting a range of well-characterised interfacial properties. Examples will be taken from collaborations developed within the ONR Marine Coatings programme and the EC Framework 6 Integrated Project ‘AMBIO’ (Advanced Nanostructured Surfaces for the Control of Biofouling).