Researchers at Swansea University have designed concrete panels to be affixed to a sea wall being built in Mumbles, a village on Swansea Bay, to encourage its colonisation by marine organisms and boost biodiversity.
The upgraded and strengthened 1.2-kilometre seawall will help protect the Mumbles area from flooding and is designed to last for decades. But it will also hopefully become a hotspot for local biodiversity thanks to the new panels, which are covered with ridges and patterns that mimic the rough contours of a rocky coast, providing gaps and crevices in which sea creatures can live.
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Ruth Callaway, an honorary research fellow at Swansea University and head of Blue Cube Marine, led the research to test which type of panel and location would best attract marine species. Known as the Mumbles Sea Hive project, it involved close collaboration with Swansea Council, which is managing the works, which are largely funded by the Welsh government, and with the construction company Knights Brown, the business partner in the EU-funded research project.
Callaway’s research involved placing 135 hexagonal concrete test panels on the sea wall in Mumbles, before the building work got under way. Each panel was cast with one of 13 different surface textures. The idea was to compare the 13 designs to see which would do best in attracting marine species.
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The panels were erected at three sites on the sea wall 50 metres apart, with some more exposed to the waves than others. At each site, the panels were fixed in three rows at different heights, to assess any differences according to how long they were submerged.
After a year in place, the panels were analysed and the findings were. The results revealed that panels with a surface of pronounced ridges and a rough structure were best for attracting marine species. The most common species that colonised the panels were two types of barnacles, which are also common along the rocky coasts of the area. Periwinkles and limpets used the spaces on and between the panels for grazing and shelter. However, no species colonised the panels that were most exposed to waves and there was far more marine life on the lowest row of panels, which was submerged under water for longest.
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The team building the seawall then drew on these findings in making their final decisions for the project. The final design incorporates hexagonal grooves to provide additional shelter for marine species, in line with the research findings. The panels are being cast in concrete on site.
‘It’s great to see this research translated into a major real-life engineering project that will enhance our local environment for generations to come,’ Callaway said. ‘The Mumbles seawall is one of the first major engineering projects in the UK to incorporate this kind of research. Swansea Council deserves enormous credit for having the courage and will to make it a reality. The way in which the project was planned and delivered, with all partners involved – from designers to concrete manufacturers – was vital to its success. We hope this will inspire similar projects.’
‘From its inception, the Swansea University Mumbles Sea Hive research project was critical in engaging with and informing the diverse stakeholder group for the Mumbles seawall development,’ said Clare Wood an expert in sustainable construction methods from Swansea University. ‘We are excited to continue to work with key partners such as Blue Cube Marine to lead research in sustainable engineering innovation and biodiversity enhancement.’
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‘We’re delighted that the new sea defences will both protect the community and encourage biodiversity,’ said council cabinet member Andrew Stevens said. ‘It’s great to see the fantastic Sea Hive project taking shape along with the rest of the new-look seawall and prom. The prom itself will feature lots of new soft landscaping that, along with the existing greenery, will provide noticeable ecological enhancement, making Mumbles yet more attractive to the public and beneficial to the environment.’