Application of novel 3D imaging techniques to quantify biomass and secondary production associated with North Sea artificial structures.

Anthropogenic structures are deployed in marine environments to support industrial activities worldwide. Sessile epibiota rapidly colonise structures in the sea, in turn attracting mobile invertebrates, fish and top predators. Understanding the ecosystem effects of the increasing number of man-made structures in marine environments is a priority for research, and necessary to support sustainable installation and decommissioning practices worldwide.

Secondary production is a measure of energy flow through the food-web, and relates directly to ecosystem function, thus secondary production is a proxy for ecosystem function. In order to understand the relationship between secondary production and wider ecosystem processes (e.g. mobile mega fauna behaviour), we need to accurately predict secondary production (the focus of this proposal), and make this data available to ecosystem modellers.

Obtaining bespoke data on secondary production associated with offshore structures is limited by the time/cost constraints of conducting dedicated ecological surveys. Offshore energy operators use remotely operated vehicles (ROVs) to obtain videos of infrastructure for maintenance purposes. These videos cover all structures types, ages and locations. Recent advances in "Structure from Motion Photogrammetry" mean that it is now possible to generate 3D images of epibiota from this video footage, and use the 3D images to estimate the biovolume of epibiota. Biovolume can be converted to biomass, then to secondary production, by applying taxa-specific conversion factors. By pairing 3D imaging with supervised machine learning algorithms to automatically identify taxa, (and then apply the taxa-specific conversions), large volumes of ROV data can be rapidly processed to produce high-resolution estimates of secondary production for entire structures /production basins.

In a previous feasibility study, we pioneered 3D imaging of man-made structures in temperate and tropical waters, and used these images to estimate epibiota biovolumes. We have developed and applied protocols to convert biovolumes into biomass via taxon-specific calibration curves. Here, we propose to generate 3D images for 85 man-made structures located in the North Sea, and wider UK waters, using existing ROV footage. From the images, we will estimate the biovolume of the observed taxa. We will then develop/refine machine learning algorithms to automatically identify the taxa within the 3D images, and apply taxa-specific volume-to-mass calibration curves. We will bring these developments together to estimate secondary production on the 85 man-made structures, and develop a statistical model of secondary production as a function of structure location, type and age, which can be applied to other structures. Our novel approach will enable us to
(1) generate, for the first time, an estimate of secondary production across all offshore energy structures within the whole North Sea ecosystem,
(2) predict changes to ecosystem function stemming from a range of installation/decommissioning scenarios, and
(3) cross-validate/compare our estimates to natural reef habitats and structures in Gulf of Mexico, Australia and the Gulf of Thailand, where similar techniques are being applied.

Our research, which addresses INSITE2 Challenges 2 and 3, will significantly advance our understanding of the ecological role played by man-made structures, and serve as an evidence base to support local, regional and global assessments of the ecosystem-scale consequences of installing and removing structures. Through development of 3D imaging and auto-ID, we will also deliver a novel monitoring tool that facilitates a strategic whole-system approach to the monitoring/regulation of offshore structures. Such a tool could be readily applied to historic industry data for ecological (and engineering) applications.

Our Pathways to Impact and careful choice of partners will deliver immediate and long-term benefits to industry, governments and society. The non-academic beneficiaries of the NorthSea3D project are listed below:

Benefits to Offshore Energy Industry: Operators face a challenge in selecting the most economical, and environmentally justified, methods for decommissioning infrastructure. In all major production basins, operators must assess the environmental impacts of decommissioning and undertake stakeholder consultations. NorthSea3D will provide two key benefits to industry:

Benefit 1: The regional estimates of epibiota secondary production and biomass associated with platforms, made available via open-access GIS layers, will serve as an evidence-base to support environmental impact assessments facilitating fast, effective and transparent decision-making. Operators will be able to use the data layers to optimise decommissioning practices, meet their environmental goals and demonstrably, and transparently, comply with relevant national/international legislation. Common research methodologies and access to comprehensive environmental data for production basins will help operators adopt globally standardised approaches to environmental impact assessment. Efficient decision-making and standardised global assessments will reduce decommissioning costs and maintain 'social licence' to operate in the sector.

Benefit 2: The development and application of methods to accurately estimate the mass of epibiota associated with platforms represents an avenue for significant cost reductions to global industry (and governments/society - see below). Accurate mass estimates will benefit industry via (1) informing selection of epibiota (marine growth/biofouling ) removal strategies and lifting/vessel procedures and technology during decommissioning, (2) optimising cleaning regimes to minimise disruption to energy generation and the marine environment and (3) informing the design of new infrastructure to account for the damaging consequences of biofouling (abrasion, component wear).

Benefits to governments: European governments (and elsewhere) are liable for significant proportions (up to 70%) of decommissioning costs (total UK costs ~£82.7 billion). Policy decisions, therefore, have major budgetary implications for society, as well as environmental consequences, and it is vital that they are based on the best available scientific evidence. The NorthSea3D project will contribute to a network of national and international scientists, promoting a common research framework that will enhance consistency and transparency in decommissioning policies and, ultimately, help ensure the sustainable exploitation of global marine ecosystems.

Benefits to society and the general public: Evidence-based decommissioning policies will directly benefit society by ensuring efficient use of public money and continued protection of environmental and stakeholder needs including ecosystem-service provision. This will secure the future of shared resources and ocean-derived societal benefits on a global scale. The NorthSea3D project will provide long-term benefits to society through knowledge exchange with governments and the provision of data to support policy development at local, national and international levels.
We have demonstrated the ability to achieve significant impact from our offshore energy research, with our results currently being used to support international policy development and to support industry in selecting cost-effective, environmentally-sound decommissioning strategies (see previous track record). We will use our existing excellent knowledge exchange pathways in combination with the project partners' networks to maximise the economic and societal benefits of the NorthSea3D project.