Why is this research important?
A developing coastline
A significant proportion of the World’s coasts are urbanised, with more than half of the global populating living at the coast. This means the need for structural defence against flooding and erosion in these areas is high, and will increase in the future as a result of increased storminess and higher sea levels associated with climate change.
Seawalls, jetties, breakwaters, pontoons, harbour walls, and pilings can be made out of a wide range of materials, which may differ significantly from the natural rock or sand substrate. Composition (e.g. rock type), surface characteristics (e.g. roughness), orientation, height (within the tidal frame), and exposure to wind, waves, and sunlight may be very different between artificial structures compared to unaltered natural shores. Although coastal structures (e.g. seawalls) are readily colonised by intertidal organisms, the types of microhabitats that they provide may lead to different sorts of plants and animals growing on them, and often in lower numbers, compared to natural shores. These sorts of biological responses to artificial structures, the reasons behind them, and their ecological implications are growing areas of research at a global level
Social and amenity value
Public opinion of new coastal development is often very strong; people that will benefit from greater levels of protection may be in favour of coastal defence schemes, such as seawalls, while others may be concerned for the potential damage to the environment and visual impact on the coast. Given that more hard structures will be required in certain areas in the future, as sea-level rises, we need to find ways of addressing both ecological and social concerns. Identifying simple ways to mitigate environment impacts and to promote the establishment of a rich ecological community on new coastal defence structures wherever possible provides significant opportunities to achieve this. This is referred to as ‘habitat enhancement’ or where habitat is being restored: ‘ecological restoration’.
Environmental policy both in the UK and Europe recognises the significant biodiversity value of coastal habitats. In the UK, coastal and intertidal environments and specific intertidal species feature heavily in the list of priority habitats for protection set out in Biodiversity Action Plans, as well as Sites of Special Scientific Interest (SSSIs). Many of our coastal habitats are also protected under European legislation, such as Natura 2000 which has been implemented using Special Areas of Conservation (SACs) and Special Protection Areas (SPAs) in the UK. This means that any major infrastructure or development work in the coastal zone, may require habitat enhancement, often as part of the environmental impact assessment process required for many new developments.
The Water Framework Directive (WFD) places further emphasis on mitigating the impacts of coastal development on the environment, requiring all feasible measures to be taken to minimise the impact of structures whilst maximising their ecological potential wherever possible. Implementation of the hydromorphology-element of the WFD relating to new structures may draw on other legislation controlling the environmental impacts of development, such as environmental impact assessment.
For effective mitigation measures to be designed and implemented, much research is needed to examine the following key questions:
- What are the design features of hard structures that have the greatest influence on marine ecology, at a range of scales?
- How might structures be designed to improve or manipulate these important features to improve ecological potential, in a feasible and cost-effective way?
- How effective are designed mitigation measures when implemented as part of full-scale defence works – do the measures provide significant ecological and social gains?