Overview
ISO 23731:2021 - Marine technology - Marine environment impact assessment (MEIA) - Performance specification for in situ image-based surveys in deep seafloor environments provides minimum requirements and recommendations for acquiring image-based data on the deep seafloor. The standard focuses on non‑destructive, long‑term monitoring where epifauna and benthopelagic fauna ≥ 1 cm are used as proxies for biological community status. It is intended to support MEIA, seabed mining monitoring, scientific research and seafloor observatory deployments.
Key topics and technical requirements
- Imaging principle: Fixed‑point, in situ image-based surveys (video or high‑frame stills) to capture organism behavior, activity and particle motion without disturbing habitats.
- Organism size: Target fauna with a minimum dimension of 1 cm as proxies for community assessment.
- Frame rate & duration: Capture as video or stills ≥ 15 fps, with each imaging event ≥ 5 s.
- Sampling schedule: Imaging events at 6–8 hour intervals or less to permit diel and temporal analyses; long‑term series (e.g., up to a year or more) recommended for seasonal cycles.
- Platform types: Supports both stationary platforms (moorings, landers, observatories) and moving platforms (AUVs, ROVs, HOVs). Repeated observations should re‑image ≥ 50% of prior area/volume.
- Angle, scale & altitude: Camera angle relative to seafloor and altitude must be known/recorded; scale recoverable via stereo calibration, laser scaling or known reference objects.
- Illumination: Use white light with recorded intensity/wavelength; red light permitted as supplementary illumination.
- Baiting: Standardize bait size so flesh is consumed within 7 days; bait placement in field of view to assess scavenger/predator presence.
- Environmental sensors: Co‑deploy CTD or equivalent to correlate images with temperature, salinity, currents and other physicochemical data.
- Data and metadata: Synchronize all instruments to a single clock (frame‑level or ≤1 s drift). Archive in viewable, preferably non‑proprietary formats; recommended container and metadata practices (example filename: PLATFORM-YYYYMMDD-HHMMSS-CAMERA1-01.mov). Higher‑bit codecs (e.g., Apple ProRes ≥10‑bit, 422 LT or better) are recommended for post‑processing.
Applications and users
- Marine researchers conducting deep‑sea biodiversity, behavior and ecological variability studies
- Environmental impact assessors and consultants for offshore developments and seabed mining
- Regulators and permitting authorities requiring standardized monitoring protocols for MEIA
- Observatory and vehicle operators (AUV/ROV/HOV/landers) designing long‑term imaging programs
- Data managers and analysts implementing synchronized metadata, archiving and QA/QC workflows
Related standards
- ISBA/25/LTC/6 - guidance for environmental assessment in marine mineral exploration (referenced normative guidance)
- ISO/TC 8 (Ships and marine technology), Subcommittee SC 13 (Marine technology) - committee responsible for this work
Keywords: ISO 23731:2021, marine environment impact assessment, MEIA, in situ image-based surveys, deep seafloor, seafloor observatory, AUV, ROV, video monitoring, seabed mining monitoring.
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