An interview with Rohan Smith, a director for marine projects at Natural England, one of the partners in the RaNTrans project.
Tell us about your project?
A critical environmental challenge for intertidal and coastal areas in the southern England and northern France is the elevated nutrient levels caused by inputs of fertilizers and human waste. This water quality reduction causes excessive growth of plants (termed eutrophication). Coastal eutrophication results in the growth of green algal mats on intertidal mudflats covering thousands of hectares.
To address this, the RanTrans project aimed to find innovative and cost-effective methods to reduce excessive seaweed growth in coastal areas of the Channel region.
Using two sites per country, we developed algal mat removal and nutrient reduction techniques specific for intertidal mudflats, including:
The four sites that these methods were tested in England were The Solent, Langstone Harbour and Poole Harbour, Holes Bay, and in France: Baie des Veys, Calvados and Ledano Mudflat, Côtes d’Armor.
What have been the key outputs and results for RaNTrans?
Seaweed coverage was predicted by modelling physical and nutrient conditions at the two English estuaries; Langstone and Poole Harbours. Our model simulations indicated that seaweed coverage at these sites was strongly linked to lower current speeds.
In addition, we have developed methodologies and algorithms for detecting deposits of algae and plants on mudflats and an exhaustive database of satellite images for spots where there is excessive algae growth.
We also have a wealth of of information specific to managing poor water conditions is the main result of the project. We already have groups asking for access to the results so that they can marine net gain programmes, which seek to put environmental improvement at the heart of marine development, and other restoration projects that involve oysters and seaweed.
What lessons have you learned through this project?
By participating in the RaNTrans project we have learnt much about the scientific challenges of nutrient and excessive seaweed algal mat coverage management in our own local systems. Although nutrients and mats have been a key focus of monitoring and study in Poole harbour for many years our use of new technologies and approaches, and the placing of this new knowledge within the regional context, has made us more confident in our understanding of how we might better manage the issue.
More specifically, we learnt that Sentinel-2 high resolution satellite imagery is quite well suited for detecting and monitoring algal mats and vegetation on mudflats even though this requires low tide conditions and low cloud cover.
And we identified that detection algorithms (which is a computer method) developed require validation by field observation (testing its truth in the field), and that each field site has these characteristics even if the detection methods applied remain very close.
What have been the highlights of delivering a cross-border project?
The RaNTrans project provided a unique opportunity to collaborate with research organisations and universities in France (CEVA, ARGANS, Aleor, Université de Caen Normandie, Université de Bretagne Occidentale) and England (University of Portsmouth, Bournemouth University, Natural England). The diversity of the sites tested and the contact with the different partners helped drive forward new methods to reduce nutrient levels in coastal regions.
A particular highlight for us has been the valuable and ongoing scientific exchange throughout the project with a diverse array of international, and domestic, colleagues. As a result, we have learnt a great deal about the technical and scientific approaches that can been deployed to improve the environmental management of nutrients and macroalgal mats and we have all brought our unique perspectives to the challenge of a global environmental management issue. Another highlight has been the opportunity to communicate with a wide variety of stakeholders about the issues and to disseminate the understanding we have generated.
What do you hope is the legacy of the project?
The knowledge that we have gained through modelling will help identify water bodies most at risk from excessive nutrient loads and allow us to better predict the response to possible remediation options.
The experience acquired during this project can be used in other projects using high and very high-resolution imagery for different thematics.
We hope that the understanding that we have generated will be used to facilitate a wiser approach to nutrient and mat management throughout the channel region. We also hope that that the project will leave an active network engaged in cross-channel exchange and cooperation.
The project was led by University of Portsmouth in collaboration with Bournemouth University, Natural England, Cefas, University of Normandie, University of Brittany, Aleor, Argans France and Centre d'Etude et de Valorisation des Algues.The European Regional Development Fund (ERDF) contribution for this project is € 1,970,917 of a total project budget of € 2,882,288.