A new, non-invasive method to measure and monitor seagrass biomass on the seabed around England’s South West coast is being developed as part of an ongoing, collaborative project.
The innovative new technique is currently being trialled by HydroSurv and Valeport, working with the University of Plymouth and Natural England, and supported by a grant of more than £266,000 from Innovate UK’s Smart Grants program.
It builds on the concept of the acoustic reflectivity of seagrass providing valuable information to characterize submerged aquatic vegetation.
A full-stack solution consisting of a Valeport VA500 altimeter installed onto a HydroSurv REAV-28 Unmanned Surface Vessel (USV), specifically developed for this project, provides a non-invasive, cost-effective platform to survey seagrass sites.
A large, validated signal library and deep learning algorithm, developed by the University of Plymouth, deciphers the survey data to predict seagrass distribution. The data is visualized and interpreted within a cloud application created by HydroSurv.
The USV platform facilitates accurate repeat surveys that can be compared to monitor temporal changes in seagrass coverage for the planning of protection and regeneration projects at biodiversity-rich worksites.
As part of its long-standing partnership with the University of Plymouth, Sonardyne International loaned its Mini Ranger 2 acoustic positioning system with Nano beacons for the accurate positioning of diver observations during the field trials.
The full solution, which was demonstrated successfully to project stakeholders for the first time in May this year, is set to change the way seagrass meadows are monitored in the future, complementing traditional diver surveys to cover much larger areas and enable rapid re-survey work as required.
“To effectively conserve and restore seagrass meadows we need innovative solutions to enable cost effective, repeatable surveys of established meadows, plus areas being restored through projects such as ReMEDIES, to monitor change,” said Fiona Crouch, Natural England ReMEDIES Project Manager. “I’m really excited to see where this new technology will take us in supporting our seagrass conservation efforts.”
HydroSurv, Valeport and the University of Plymouth form part of a fast-emerging South West England maritime innovation cluster. The project partners are engaging with the Environment Agency and Natural England to develop the solution further, with a second phase of demonstrations planned for September 2022.
“Staying true to our values of ocean and environmental stewardship, the work being carried out within this collaborative project will directly translate into impact addressing UN Sustainable Development Goal 14, ‘Life below water’,” said David Hull, Founder and CEO of HydroSurv. “The ability to provide blended, non-invasive solutions that rapidly acquire, process and visualize the coverage and density of seagrass meadows is central to improving our understanding of these vital ecosystems and delivering regular and repeatable resurveys in- stride with the needs of coastal practitioners.”
The VA500 altimeter, which uses state of the art signal processing, was customized by the instrument manufacturer for this project.
“The VA500 altimeter was developed to deliver reliable underwater range measurements in a compact, robust package,” said Jim Gardiner, Research Scientist at Valeport. “Working with University of Plymouth and HydroSurv, custom firmware was developed to deliver low noise, high quality, correlated acoustic profiles at up to 10Hz to enable deeper analysis, exploration, mapping and classification of the acoustic information gathered by the VA500.”
“As part of the project, the application of deep learning algorithms for the acoustic detection and characterization of seagrass beds has introduced improved accuracy and efficiency over more traditional techniques,” said Dr Tim Scott, Associate Professor of Ocean Exploration at the University of Plymouth. “When combined with the advantages of lightweight autonomous survey platforms, this new combined survey solution introduces a step-change in accurate and repeatable seagrass mapping.”
Seagrass meadows are a crucial part of the marine ecosystem and are increasingly being recognized for their essential carbon capture abilities. As well as being as effective at storing carbon as woodland, seagrass also provides vital habitat for young fish, seahorses and jellyfish. It additionally cleans surrounding seawater and helps to stabilize the seabed, thereby reducing coastal erosion.
The UK has lost around half of its seagrass since the mid-1930s due to factors ranging from seagrass wasting disease (SWD) and pollution to physical disturbance from the anchoring, launching and mooring of leisure boats. The £2.5 million LIFE Recreation ReMEDIES partnership ‘Save Our Seabed’, led by Natural England and funded by the EU LIFE Programme, was launched in July 2019 to protect and restore these sensitive habitats.
