Researchers at Exeter and Plymouth are working with national and local partners as part of a collaboratively funded research project (University of Exeter, Environment Agency, Great Western Research, University of Plymouth) to examine whether and how different rock materials influence the nature and rates of biological colonisation on coastal defences. We are currently sharing the results of our research with local communities and stakeholders, as well as conducting a follow-on research project.
The primary focus of the research was to examine the two-way interplay between organisms and geomorphology, to explore how a biogeomorphological approach can be used to assist biodiversity enhancement. The project was highly interdisciplinary, involving researchers with expertise in ecology, geomorphology and geology. There are three main components of the research:
1. The response of biology to different material types used in coastal defence construction
We are looking at how different construction materials and their physical properties (e.g. material composition, hardness, and texture) at a small scale (i.e. mm – cm) influence early stages of intertidal colonisation. Thus, we are combining expertise from geology (composition, rock hardness), geomorphology (rock texture variations) and ecology in our work. Our work concentrates on microorganisms, which rapidly colonise hard surfaces placed in the sea, and barnacles, which dominate many rocky shore environments, including harbour walls.
2. The role of colonising organisms in altering material substrates over time.
Animals and plants that colonise the surfaces of coastal structures can alter the materials they are built out of through processes of bioweathering, bioerosion and bioprotection. In addition to understanding how these processes operate at a micro-scale (< cm), we are beginning to see how important these processes are in generating the sorts of textures and habitat complexities that are favourable for other organisms such as barnacles. These processes may also have engineering implications.
3. Opportunities for manipulating biological response using textured materials.
Many researchers have demonstrated the importance of surface texture in influencing the settlement and recruitment of intertidal organisms. However, relatively few studies have been done looking at the opportunities of texturing construction materials (for coastal defences such as seawalls or rock amour) for improving ecological potential. We are examining how simple texture can be applied to materials (particularly concrete) to enhance the geomorphic complexity (i.e. surface roughness) of substrata to influence colonisation when placed in the intertidal zone, and how material choice may be important for enabling favourable textures to develop naturally.