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The impact of natural physical disturbance on diversity of deep-sea
nematode communities has been recently investigated 20 . That paper
reported the impact of benthic storms at the HEBBLE (High Energy Benthic
Boundary Layer Experiment) site in the North Atlantic and of turbidite flows
in the Venezuela Basin and Madeira Abyssal Plain. The results showed that
deep-sea nematodes, like shallow-water nematodes, are resistant to
physical disturbance, including smothering. Anecdotal evidence from a
deep-sea tailing-placement site is consistent with this view.
A long-term change in the composition of the sediments can cause
a change in meiofauna communities. There is some evidence for this at the
Madeira Abyssal Plain and at a site subject to current flows in the northeast
Pacific 21 . The sedimentation rate of pelagic material seems to be the
important factor in the return of the meiofauna communities to baseline
conditions 22 .
The European DISCOL programme should yield useful additional
information but the only paper yet published on the impact of disturbance
on meiofauna deals only with abundance 23 .
2. Possible Impact of Nodule Exploration and Exploitation
Nodule exploration and exploitation are likely to have four types of
impact on the meiofauna communities: (i) the direct physical effect of the
mining equipment, (ii) the settlement of the plume of sediment, (iii) any
long-term change in sediment composition and (iv) productivity changes.
It is difficult to predict the effect of the machinery. Nematode
communities tend to be resistant to the mechanical effects of natural
physical processes that cause sediment disturbance but whether this will
apply to the processes involved in nodule exploitation is unclear.
Nematodes are resistant to plume effects and may tend to recover from
such disturbances rather quickly. However, meiofauna communities will be
sensitive to any long-term change in the physical composition of the
sediment caused by exploitation. This may be a problem for some species.
Sediment disturbance normally releases organic material, temporarily
increasing productivity, and this causes a short-lived rise in local diversity.
INTERNATIONAL SEABED AUTHORITY 373