Minerals Report - International Seabed Authority

local geology, sedimentology and mining activity. To maintain objective
assessment, the reviewer was not informed whether the submersible was
positioned in mined or unmined terrain, and sections of video where data
was considered to be ambiguous were removed as part of the quality
assurance procedures.
At the end of each dive analysis, the quantity of time spent in each
habitat was totalled to provide frequency of occurrence data. Whilst
relatively crude, this provided insight into how the environment can be
partitioned within a dive or summed across dives for comparative
purposes. Examining the relationship between nekton abundance and
feature frequency assessed associations between nekton and
environmental features. Multiple regression was used to analyse the data.
Example of physical and biological descriptions from dive analysis:
Dive 14 [27]
Unmined: Sediment thick and textured, with numerous biogenic
holes of diverse shape and size. Without sessile fauna projecting through
surface. Hard substrata patchy. Boulders large and slab-like, on surface:
with thick sediment layer and sparse epifauna on upper face, epifauna
more diverse and thick on vertical faces. Small cobbles projected through
sediment, scattered (never aggregated in piles) with sparse epifauna.
Massive boulders infrequent and with sparse epifauna.
Mined: Sediment thick and for the most part as above. Else thin, flat
and with few biogenic holes. Some areas thickly covered with shell debris
(common), without any biogenic holes or projecting epifauna.
Cobbles and boulders aggregated densely, often without
superficial layer of sediment, completely without epifauna.
3.3.2 Post 1996 Video Transect Analysis
A further dive programme was conducted with Jago during 1997.
The primary objectives were to investigate the influence of different
geology on mining system efficiency and effectiveness and to characterise
different ore body types in detail to aid the interpretation of highresolution
geophysical data. Hence the biological content of videotapes
was largely incidental. Some dives were, however, focused on
environmental data acquisition.
INTERNATIONAL SEABED AUTHORITY 636