ISO 23731:2021

INTERNATIONAL ISO
STANDARD 23731
First edition
2021-07
Marine technology — Marine
environment impact assessment
(MEIA) — Performance specification
for in situ image-based surveys in
deep seafloor environments
Reference number
©
ISO 2021
© ISO 2021
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Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Principle . 3
5 Performance requirements and recommendations . 3
5.1 Angle and scale of the monitoring . 3
5.2 Illumination . 3
5.3 Bait . 3
5.4 Image capturing schedule/timing . 3
5.5 Data synchronization and management . 4
Annex A (informative) Example of seafloor observatories . 5
Bibliography .10
Foreword
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iv © ISO 2021 – All rights reserved

Introduction
From the mid-1990s, attention has been paid to potential environmental impacts to deep-sea
[2]
environments caused by sea debris, bottom trawling, seabed mining, etc .
In situ observations of the deep-seafloor provide useful data sets to assess the amount of natural
[3]
variation in biological systems over a range of different spatial and temporal dimensions . They can
also provide data on recruitment and community succession patterns. Imaged-based surveys are an
integral component of underwater surveys conducted both with moving platforms (e.g. ROVs, HOVs,
[4, 5, 6]
AUVs) , and stationary platforms (e.g. moorings, buoys, standalone seabed platforms, cabled
[7, 8]
observatories) . The images have the potential to provide a broad range of significant scientific
information and educational benefits long after data acquisition and are non-destructive to the
monitored environments. In order to obtain the necessary spatial coverage for robust statistical
analyses of the intrinsic variability within environments and their associated biological ecosystems, it
[9]
is necessary to deploy multiple standalone seabed platforms concurrently .
In the case of seabed mining operations, it will be necessary to accumulate long-term data sets of
different environments within the proposed mining field and downstream where any sediment plumes
can be expected to be transported in order to detect and monitor any environmental impacts due to the
extraction and processing of minerals (see ISBA/25/LTC/6). As such, a standard for long-term in situ
image-based surveys in deep sea environments needs to be developed for use in such scenarios.
This document gives specifications for in situ image-based surveys in deep seafloor environments to
be used for marine environmental impact assessments and other purposes where a long-term image-
based survey in the deep-sea is required.
INTERNATIONAL STANDARD ISO 23731:2021(E)
Marine technology — Marine environment impact
assessment (MEIA) — Performance specification for in situ
image-based surveys in deep seafloor environments
1 Scope
This document specifies minimum requirements and provides recommendations for the gathering of
image-based data at seafloor where epifauna and benthopelagic fauna with a minimum dimension of
1 cm are used as a proxy for the status of the biological community.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments) applies.
1)
ISA ISBA/25/LTC/6, Recommendations for the guidance of contractors for the assessment of the possible
environmental impacts arising from exploration for marine minerals in the Area, 2013. Available at https://
www .isa .org .jm
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISBA/25/LTC/6 and the following
apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
3.1
autonomous underwater vehicle
AUV
underwater robotic vehicle that does not have a tether to the surface
Note 1 to entry: AUVs are pre-programmed to operate over a particular course or to respond to sensor data or
perhaps acoustic commands. Applications include surveying, scientific data collection and mine-hunting.
3.2
benthopelagic
pertaining to the zone very close to, and to some extent having contact with, the sea floor of deeper
portions of the open ocean
1) ISA: International seabed authority.
3.3
codec
compression/decompression algorithm used to take a raw stream of audio and/or video data and to
make it smaller by removing elements that are deemed unnecessary, and later to take the compressed
stream and restore the original version so that it can be replayed on a display and/or sound system
Note 1 to entry: Some codecs attempt to only remove elements that the average person would never miss, while
others notably reduce the image or sound quality, usually in order to make the content as small as possible
for transmission over slow or low bandwidth connections. Codec selection is usually based on what is more
important: quality or size/speed of the transmission.
3.4
container
outer shell of a media file that organizes the stream(s) that it carries
Note 1 to entry: A particular container format can support several different encoding formats (e.g. H.264, WMV,
Sorenson AVC, RealVideo, DivX and ProRes 422), and no container format can handle every possible encoding
format. Thus, for example, there can be two different MOV files, one of which plays just fine on a computer, while
the other fails to play, due to that computer having a codec (3.3) for the encoding format of the first file, but no
matching codec for the encoding format found in the second file.
Note 2 to entry: Most video files have one video data stream and one audio data stream, but can contain multiple
audio streams (possibly in different languages, or to support special surround-sound systems), or even additional
video streams (to support watching the same program from multiple angles). The container format of a file is
usually directly connected to the file extension or MIME type (e.g. Quicktime MOV, RealMedia RM, MPEG, MP4,
Windows AVI, Windows WMV).
3.5
epifauna
organisms that live on the surface of the sediment/substrate
3.6
mooring
physical platform (3.8) containing a buoyant element constrained to a geographic location by an
anchoring device
3.7
observatory
infrastructure that is able to accommodate sensors and instruments either permanently installed or
by demand, to provide certain services like power supply and communication links for all connected
instruments
EXAMPLE Global, regional.
3.8
platform
collection of nodes, sensors and instruments together with necessary controllers physically connected
together, with a known external geometry
EXAMPLE Mooring (3.6), surface mooring, profiler, AUV (3.1), glider.
3.9
resolution
smallest amount of input signal change that an instrument/sensor can detect reliably
3.10
scavenger
organism that eats waste products and dead remains of other animals and plants that it did not kill
itself
2 © ISO 2021 – All rights reserved

4 Principle
The suggested protocols are image-based as these methods are non-destructive to the monitored
environment
...