The application of underwater acoustic and visual 3D mapping technologies for the study of deep ocean ecosystems.

The deep ocean is the largest habitat for life on Earth, yet scientific understanding of this ecosystem remains limited. The data available shows that although deep sea biodiversity provides vital ecosystem services to support life on Earth, global anthropogenic threats are already impacting its persistence. This demonstrates the urgency to inform, create and implement a framework for sustainable deep ocean governance. Scientific understanding of the drivers of deep ocean biodiversity is essential for such a framework, but the high requirements of conducting a scientific expedition limit extensive sampling.
Applying 3D mapping methodologies to deep ocean habitats can reduce the sampling time needed underwater and increase the amount of data collected from an area. Whereas acoustic mapping of sea-floor features for bathymetry is well-developed, optic 3D mapping using video material is not as common. Yet, optic maps can provide important visual details uncaptured by acoustic methods.
This research will explore the potential of selected acoustic and optic technologies for the 3D mapping of deep sea habitats, with the aim of reducing precious sampling time in situ and increasing information about deep sea habitats to inform their governance. Specifically, it will aim to develop methodologies to create and analyse 3D maps of deep ocean ecosystems by combining input from multibeam sonar, photogrammetry and photomosaics. The suitability of these new technologies for marine biological science will be tested by analysing the relationship between 3D habitat heterogeneity and biological communities in the Indian Ocean at different scales and at depths between 0 and 500 m.
Systematic surveying at different depths will take place at in multiple parts of the Indian Ocean. Multibeam sonar (Teledyne SeaBat T50-P) will be deployed from the ship to characterize the seafloor profile. Multibeam maps will be created using established data collection and software (Reson PDS). Post-cruise a method will be developed to analyse the maps for measures of habitat complexity (Teledyne CARIS). A new protocol will be developed to collect and process video images for photogrammetry. Different platforms will be used to collect video material (subs, ROVs, divers) and training will take place with pilots and divers on best practices for collecting and scaling. Multiple routes will be explored to convert the collected imagery to 3D visualisations using Agisoft PhotoScan. These models will be analysed for habitat complexity information following an established protocol in Rhinoceros. At each location, biological data will be collected using video surveys. Post cruise these surveys will be analysed to inform how habitat characteristics influence biodiversity in this part of the deep ocean.
This research will take place in collaboration with the Nekton Foundation as part of mission 'First Descent' to improve our understanding of deep ocean biodiversity patterns and their environmental drivers in the Indian Ocean.