Development and characteristics of an adhesion bioassay for ectocarpoid algae

Abstract

Species of filamentous brown algae in the family Ectocarpaceae are significant members of fouling communities. However, there are few systematic studies on the influence of surface physico-chemical properties on their adhesion. In the present paper the development of a novel, laboratory-based adhesion bioassay for ectocarpoid algae, at an appropriate scale for the screening of sets of experimental samples in well-replicated and controlled experiments is described. The assays are based on the colonization of surfaces from a starting inoculum consisting of multicellular filaments obtained by blending the cultured alga Ectocarpus crouaniorum. The adhesion strength of the biomass after 14 days growth was assessed by applying a hydrodynamic shear stress. Results from adhesion tests on a set of standard surfaces showed that E. crouaniorum adhered more weakly to the amphiphilic Intersleek® 900 than to the more hydrophobic Intersleek® 700 and Silastic® T2 coatings. Adhesion to hydrophilic glass was also weak. Similar results were obtained for other cultivated species of Ectocarpus but differed from those obtained with the related ectocarpoid species Hincksia secunda. The response of the ectocarpoid algae to the surfaces was also compared to that for the green alga, Ulva.

Keywords:

• marine biofouling
• brown algae
• Ectocarpus
• adhesion bioassays
• Ulva

Acknowledgements

E. Evariste thanks International Paint Ltd for a studentship supporting these studies. The authors specifically thank Graeme Lyall, Kevin Reynolds, Lyndsey Tyson, David Stark, Adam Bell, Brent Tyson, David Williams, Gabrielle Prendergast, and Jennifer Longyear (International Paint Ltd) for advice and help in the preparation and characterization of coatings. The authors also thank Dr Jeremy Thomason (Marine Ecological Services) for advice on statistical analysis.