CHARACTERISATION OF THE ADHESION OF FOULING DIATOMS ONTO TEST SURFACES

Abstract

The dominant presence of marine diatoms fouling the latest non-toxic, antifoul coatings has increased interest in characterising diatom adhesives and the mechanisms of their adhesion. In this study the adhesion of two benthic, fouling diatoms [Craspedostauros australis Cox and Haslea sp. Simonsen (Bacillariophyceae, Ochrophyta)] was measured on 23 test surfaces with different chemical properties. The adhesion of the diatoms was measured using a simple and effective bench-top flow chamber. Self-assembled monolayers were used to create a range of surfaces with specific chemical properties, allowing the direct assessment of adhesion strength to substrata with different chemical properties. PDMSe-[poly(dimethyl siloxane) elastomer], ‘Intersleek’®, gold-coated glass slides, and acid-washed glass were also tested. No single chemical functional group was found that significantly reduces the adhesion of the diatoms. However, results show a negative linear correlation between the percentage of cells removed (C. australis 80%-0%, Haslea sp. 60%-0%) and surface contact angle (7°—105°) both species adhering more strongly to hydrophobic surfaces. This study introduces a simple, inexpensive and reliable bench-top flow chamber and shows that the adhesion of biofouling diatoms is mainly influenced by the physical properties of surfaces as defined by wettability.