The combination of increased storminess, sea level rise and urbanisation will result in the continued proliferation of coastal protection. This will often necessitate hard infrastructure, such as seawalls and rock revetments being placed in coastal settings. UK government strategies state that infrastructure needs to be sustainable, resilient and designed to work with nature. Urban ecosystems, including coastal hard infrastructure, have significantly lower biodiversity than equivalent natural habitats . A growing body of research, however, shows that hard infrastructure can be designed to support biodiversity more akin to that found on natural rocky shores [1,2] while not impact on engineering function. There is now an increasing tool-kit of inexpensive ecological enhancement options which can transform grey infrastructure into more resilient and sustainable components of urban coasts[1,3]. Research in this field is maturing and uptake of these designs in practical engineering projects is increasing, but key research gaps still remain. Working in close collaboration with the project’s CASE partner the Environment Agency, this project will address four key research gaps:
1. Scaling up from experimental studies to operational, whole engineering structure application.
To date eco-engineering research has been at the experimental scale. What is urgently needed is for this research to be scaled up to look at the biodiversity benefits of scaled eco-engineering enhancements. This is now possible as the early experimental scale research has led to eco-engineering interventions being deployed at scale. This scale of research allows us to 1) assess what scale of active ecological enhancement of engineering structures are required to have appreciable ecological benefits and ii) which combinations of rock mass and material properties, and resulting geomorphic features have the greatest ecological benefit using passive ecological enhancement techniques. Additionally, longer timeseries datasets are a gap in eco-engineering science and this project would allow whole-structure monitoring of engineering schemes with passive enhancements (e.g. Hartlepool) 8 years after construction, alongside monitoring of active enhancements undertaken by the Environment Agency (e.g. Elmer Scheme, Natural Resources Wales and Milford Haven Port Authority (e.g. Milford Haven enhancements) and Nature Scotland (e.g. the Wildline Project) schemes all constructed in 2020.
2. Bioerosion – Material choice interactions.
One of the lesser studied topics in eco-engineering is measuring the interactions between biota and rock /concrete materials, where biota often erode rock, helping shape important habitat niches on engineered assets through time (called biogeomorphic ecosystem engineering). Here field and laboratory experiments will be undertaken on a range of rock and concrete materials (hereafter, materials) commonly used in coastal engineering to quantify differential bioerosion rates. These data would advance ecology and biogeomorphology science, and also help identify which materials are best suited for ecological enhancement in operational applications.
3. Bioeroders as “Natural Cleaners”
Some structures, such as access slipways, steps on piers and ferry routes in UK harbours, require routine maintenance to clean these surfaces to remove algae which causes slip hazards for people. These procedures are economically costly and can also be damaging to marine life. What if the biogeomorphology and ecology research on biotic-rock and cross-scalar biotic interactions, can be used to create a biological “natural cleaning” solution – reducing the need for chemical cleaning of these surfaces? Gastropod grazers are known to control algal coverage on natural rocky shores, but no attempt has been made to transfer this role into controlling nuisance algae on engineered structures. Here the student will investigate the species, ecological enhancement, spatial arrangement and density of grazer and intervention to best control nuisance algae an in so doing reduce maintenance costs and ecological impacts.
4. Facilitating widespread implementation of eco-engineering in operational practice.
One of the largest eco-engineering challenges is operationalizing the toolbox of eco-engineering interventions into large scale commercial projects. These implementation challenges can happen across the life cycle of a project from conception, through to detailed design, tendering and construction. The student will work with the Environment Agency (case partner) to identify existing policy and practice best practice, as well as implementation opportunities and barriers. This information will be used to co-produce a best practice routemap for improving application in operational practice.
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Photographs showing limpets, limpet grazing marks on sea walls and coastal engineering structures. Source: Naylor