Invasive species are one of the biggest threats to global biodiversity and are associated with huge economic costs. The biggest vector for marine invasive species spread is shipping, making harbours hotspots for marine invasive species. Concrete is one of the main materials used in harbours. Biofouling organisms have been shown to be influenced by changes to the surface properties of materials at both species and community level. Six types of concrete were selected for study based on their possible ability to reduce biofouling by marine invasive species; Portland cement, GGBS, a formliner-altered surface, two exposed aggregate surfaces and the first ever hairy concrete surface. Physical properties (roughness and mercury intrusion porosity) and chemical properties (XRD, XRF and pH) of each type of concrete were categorized. Five harbours were searched from Arbroath to North Queensferry on the East Coast of Scotland for invasive species. Panels of concrete were deployed at three locations on the East Coast of Scotland for 21months. At one location panels were also removed at 4, 7 and 21-months to measure colonisation, and deployed from April to August and August to December to explore the influence of seasonality. A total of eight invasive species were found in the harbour searches and biofouling studies. No type of concrete within this study resisted biofouling by marine invasive species after 21-months across all three locations. The invasive barnacle Austrominius modestus had significantly lower cover on hairy concretes at two locations and exposed aggregate concretes at one location. Changes to the physical properties to the surfaces of concrete had more of an influence on biofouling than chemical changes. Both micro (sub mm) and macro (mm+) changes to roughness influenced biofouling. This study cannot recommend one singular type of concrete for the reduction of marine invasive species but presents further quantitative information about how biofouling, of both invasive and native species, interacts in the field environment with the properties of concrete surfaces.
|Date of Award
|Engineering and Physical Sciences Research Council & Leverhulme Trust
|Thomas Dyer (Supervisor) & Qi Zhao (Supervisor)