AN INNOVATIVE new technique to monitor seagrass on the seabed around the South West coast is being trialled by Totnes-based Valeport.

The company is collaborating with Exeter-based HydroSurv to develop enhanced solutions for seagrass monitoring, using a new and non-invasive method.

The trial is being funded by a £266,000 grant from Innovate UK’s Smart Grants programme, and both companies are working with the University of Plymouth and Natural England.

The method builds on the concept of the acoustic reflectivity of seagrass providing valuable information to characterise submerged aquatic vegetation.

Valeport’s VA500 altimeter, a hydrographic instrument used for measuring underwater positioning, is installed onto a small Uncrewed Surface Vessel (USV), built by HydroSurv and with specific modifications for this project.

Remotely controlled and with no people onboard, the USV provides a non-invasive and cost-effective platform for seagrass site survey.

Valeport customised the VA500 altimeter, which uses state of the art signal processing, for the seagrass project.

Jim Gardiner, Valeport’s research scientist said: “The VA500 altimeter was developed to deliver reliable underwater range measurements in a compact, robust package.

“Working with University of Plymouth and HydroSurv, custom firmware was developed to deliver low noise, high quality, correlated acoustic profiles to enable deeper analysis, exploration, mapping and classification of the acoustic information gathered by the VA500.”

A large, validated signal library and deep learning algorithm, developed by the University of Plymouth, deciphers the survey data collected by the USV to predict seagrass distribution.

The data is visualised and interpreted within a cloud application created by HydroSurv.

Seagrass meadows are a crucial part of the marine ecosystem and are increasingly being recognised 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 also cleans surrounding seawater and helps to stabilise the seabed, thereby reducing coastal erosion.

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.

The full solution, which was demonstrated successfully to project stakeholders in Cawsand Bay, Looe and on the River Yealm 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.

David Hull, HydroSurv’s founder and chief executive said: “The ability to provide blended, non-invasive solutions that rapidly acquire, process and visualise 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 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.