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Biogeomorphology of coastal structures
Artifi
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UNDE RST ANDI NG I NT E RA CT IO NS B ETW EEN HA RD S UBST RAT A AND COLO NIS I NG
O RGA NIS MS A S A T O OL F OR E CO LO GI CA L E NHANCE MENT
Biogeomorphology is an integrated approach to understanding the environment, examining the two-way interaction between organisms and the physical landscape. Research funded by the Environment Agency and Great Western Research, based at the Universities of Exeter and Plymouth, used this approach to improve understanding of how animals and plants respond to materials used in coastal engineering, and how structures might be enhanced for biodiversity gains.
Hard coastal structures like sea-walls and breakwaters are essen-tial for coastal erosion and flood risk management, and economi-cally valuable port and harbour activities. These structures act as new habitats in their own right, becoming colonised by animals and plants, but the diversity of the organisms they support is typically lower than on natural rocky shores.
Coastal engineering activities must minimise any adverse im-pacts on the environment, and the Water Framework Directive re-quires that ecological potential is maximised wherever possible. Finding ways to enhance artificial structures so that they may better mimic natural shores (ecologically) is therefore a research and con-servation priority.
SURFACE TEXTURE Barnacles show strong responses to substratum surface texture. Species studied by research-ers at the University of Exeter showed a positive response to fine-scale (millimetre) textures when applied to common engineering materials. Making grooves in the surface of concrete whilst curing increased colonisation rates by over 100% compared to the smooth concrete that is often used in coastal engineering. By encouraging early colonisers like barnacles, these simple methods could enable more species to establish, and more quickly.
June 2013
The physical characteristics of materials used in coastal engineering influence which organisms colonise – and how quickly.
“Organisms
change the physical
properties and
behaviours of the
materials they grow
on.”
We now need to determine the sorts of features that are most important for different organisms, so that priority species can be targeted. Collaboration with engineers and coastal managers is needed to examine how these features can be successfully incorporated in the planning, design and operation of coastal structures.
Field and laboratory investigations have shown that microorganisms alter the roughness of rock and concrete through 'bioerosion'. This can create ecologically favourable textures that are often absent from artificial structures, and reduce ecological stress by helping rocks stay cool and wet during periods of low tide. On-going research suggests that in some situations marine species can protect buildings materials from deterioration through the action of salts (termed ‘bioprotection’). This includes barnacles and seaweeds that keep surfaces cool and stop them from drying out. Enhancing the design of structures for ecological gains can therefore provide additional engineering benefits.
Biogeomorphology offers an integrated framework within which physical and biological processes (and their influences on each other) can be studied. Understanding these feedbacks requires inter-disciplinary knowledge, but this is essential for successful management of the environment.
Dr. Martin Coombes ([email protected]) School of Geography and the Environment, University of Oxford
Dr. Larissa Naylor ([email protected])
School of Geographical and Earth Sciences, University of Glasgow
www.exeter.ac.uk/coastaldefencesbiodiversity
© 2013
