Minerals Report - International Seabed Authority

unquestionably be alarming, and the future of the industry could be in
doubt. However, in the continental shelf environment studied by DBM, it
can be demonstrated that sterilisation does not occur, based on both
conventional sampling, which indicates that recovery can occur in 4 to 8
years and from submersible-based visual observation.
More recently direct seafloor observations have indicated that in
some instances mining disturbance can promote environmental
enhancement, for example by resulting in increased habitats through
surface rock exposure for rockfish such as false jacopever [9]. Non-west
coast examples of environmental enhancement have also been reported,
principally by environmental studies linked to the aggregate dredging
industry on the Scotia Shelf of Canada, where environmental enhancement
has resulted in improvement of lobster habitat [35]. In other instances,
dredging practices are being reviewed to examine the possibility of
deliberately creating new fishery habitats where future aggregate
extraction is being planned [36]. It is too early to determine whether
similar effects are resulting from deepwater diamond mining on the west
coast of southern Africa.
3.3.4 Impact of Resedimentation and Artificial Plumes
Offshore diamond mining generates a plume of suspended
sediment at the surface. The direction the plume travels as the material
settles changes with depth. Transport is to the northwest at surface and to
the south at depth [37].
The analysis of Jago video transects has provided clear evidence of
impact on the epifaunal species diversity, richness and total abundance at
sites surrounding those areas impacted directly by mining tool
disturbance [28]. The research indicates that there is a minimum distance
(100 to 200 m generally) from mining sites beyond which the epifauna is
not negatively impacted by mining activity (Figure 4). Similar
relationships have been noted in numerous studies of pollution in the
marine, freshwater and terrestrial environments.
The research findings based on visual observation are less
conclusive in terms of the infaunal communities, as it is currently difficult
to determine which organisms are responsible for the different types of
holes and mounds observed. It is however clear that the density of
burrows is significantly less in mined sites than it is in those furthest from
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