standardization of environmental data and information - International ...

whether the effects were severe in a particular part of the water column.
More was known about the likely effects of surface water discharge, for
example in terms of potential iron enrichment causing turbidity, but to really
understand the effects in the mid-water, some kind of discharge would have
to be tested there. There was a need for guidance regarding discharge
experiments during test mining, so that there would be enough
understanding to make a suggestion or regulation from an environmental
perspective about where discharge should occur.
The Secretary-General said contractors would have to address the
discharge issue in their environmental statement at the end of the
exploration phase, when applying for exploitation. While it was premature to
deal with the topic now given the lack of knowledge, it should be flagged for
action close to the end of the exploration phase, when mining systems were
to be tested. Some indication should be given as to how it would be dealt
with then.
Chronic versus single discharge
A participant cited information from the United Kingdom Ministry of
Agriculture that, in the case of dumping dredges and their effects on
meiofauna, it seemed better to keep hitting the same area with small doses
every so often rather than hitting one area with a huge dose all at once.
However, he did not know how that related to mining. This might be another
case where animals of different sizes, or perhaps different taxa, reacted
differently.
Smith responded that, in contrast, many studies of shallow-water
communities showed low levels of chronic disturbance to be more
deleterious than one large dose, at least for macrofauna, and particularly
deposit feeders and suspension feeders. The different results might be due
to the animals’ feeding strategies, since deposit feeders’ food resources
were diluted and those of suspension feeders were damaged by a sediment
plume. Experimentation at the seafloor would be needed to understand
this issue.
Natural resedimentation events
In connection with the threat from resuspended plumes, a geologist
wondered whether studies were being conducted of the effects of naturally
occurring instantaneous deposits such as the asphalt from the 1991
eruption of Mount Pinatubo (Philippines). Smith replied that natural events
81 INTERNATIONAL SEABED AUTHORITY