Measurements of Chlorophyll-a, the most abundant form of Chlorophyll within photosynthetic organisms, previously involved the collection of water samples for laboratory analysis, using high-performance liquid chromatography (HPLC) to determine the concentration of Chlorophyll-a present. A useful feature of Chlorophyll-a is its ability to fluoresce when excited with light of a particular wavelength. This characteristic allows for in-situ, real-time measurements of the pigment with a suitable fluorometer, dramatically decreasing both the time and cost required to obtain Chlorophyll-a measurements.
Access to real-time monitoring data is revolutionising the way in which the fisheries/aquaculture industries operate, improving efficiencies and reacting faster to potential hazards, such as HABs or eutrophication events (an excessive richness of nutrients in a water body). Whilst this data is clearly of high importance to aquaculture, measurements of parameters including turbidity and Chlorophyll-a provide insight into the health of the wider ocean, and by extension, traditional fisheries.
Sustaining global fish stocks
Most of the world’s fisheries rely on specific habitats, including seagrass meadows, mangroves and reefs, which act as nurseries for juvenile fish. Multiple cod, pollock and herring species in particular use seagrass meadows for this purpose (Unsworth et al, 2019). These habitats, however, are under great strain due to human-induced habitat degradation. On a global scale, the role of seagrass meadows within the climate system cannot be understated – they occupy ~0.2% of the seabed but can sequester 35 times more carbon than tropical rainforests (UNEP, 2019).
HydroSurv – a Devon-based USV manufacturer and operator – has achieved significant advancements in acoustic mapping techniques for seagrass assessment, initially leveraging the Valeport VA500 altimeter and an advanced machine learning toolchain to ascertain critical parameters such as seagrass coverage, density and canopy height to derive the submerged aquatic biomass and therefore the carbon sequestration potential.
Responding to requests from public body commissioners, HydroSurv has since extended the yield of data from the survey system by integrating Valeport Hyperion Chlorophyll-a and Turbidity sensors into the payload. This enhancement allows simultaneous collection of environmental data alongside hydroacoustic measurements providing a more comprehensive understanding of seagrass ecosystems and by extension, their ability to sustain juvenile fish and species critical to global fish stocks.
The resulting processed data is effortlessly hosted and visualised with HydroSurv’s EasySurv cloud-based GIS application, which not only facilitates visualisation but also empowers users with temporal difference modelling tools to monitor rate of change between individual surveys. Additionally, EasySurv offers flexibility to incorporate further metadata into datasets, enabling spatial visualisation of other parameters.
As HydroSurv enters its third phase of development, supported by co-funding from DEFRA and Innovate UK, it is now scaling its demonstration surveys. Pilot initiatives are underway at worksites in Falmouth, Plymouth and Salcombe to showcase the efficacy and versatility of HydroSurv’s cutting edge approach using Valeport products.