42 | New Scientist | 7 November 2020other habitat, which is why she says it needs
protection from mining.
The ISA is sympathetic. “If there is a
need established for protection of active
hydrothermal vents, I don’t think that’s a big
problem,” says Lodge. “It’s something that
we’re working on.” For every cluster of active
hydrothermal vents on the ocean floor,
gushing out mineral-rich fluid, there are
several inactive ones, where venting has
naturally ceased and the vent animals have
moved on, but the mineral deposits remain
for potential sulphide miners.
Most of the exploration licences aren’t for
sulphides at hydrothermal vents, however.
They are for manganese nodules: nuggets
the size of new potatoes that contain cobalt,
nickel and rare earth elements, as well as
manganese, that form over thousands of
years on the sea floor. Exploration activity is
primarily focused on the Clarion-Clipperton
Zone (CCZ) of the eastern Pacific, which covers
4.5 million square kilometres of silty abyssal
plains, punctuated by rolling “abyssal hills”.
The CCZ is 90,000 times the size of the
area of all the world’s active hydrothermal
vents, which could make mining here a very
different prospect. Nevertheless, there is
still much we don’t know about it. Just as the
environment changes over thousands of
kilometres across a continent, the huge area
of the CCZ is a patchwork of varied sea-floor
environments. Different species flourish in
these different areas, which requires ajoined-up approach to manage the impacts of
activities such as mining. We still don’t know
exactly what organisms live where or how
they might be disturbed by mining.
For example, seven years ago, when
researchers from the Natural History
Museum (NHM) in London surveyed the
eastern CCZ, they noticed white sponges,
just a few millimetres across, on many of
the manganese nodules. These turned out
to belong to a new genus and species, which
they named Plenaster craigi. It is the most
abundant animal living on these nodules
in the eastern CCZ, and has since been found
across more than 1000 kilometres of the area.
Being so widespread, it would probably not
be threatened by mining, but other
organisms are. Around hydrothermal vents
there are 27 species listed as vulnerable or
endangered on the International Union
for Conservation of Nature’s Red List of
Threatened Species. These include four
new species of snails, which I and colleagues
recently described in published work. It
remains to be seen whether any nodule
zone species, whose populations cover
much larger areas, will join them on that list.
“There has to be honesty and transparency
about what will be impacted,” says Adrian
Glover, who led the NHM survey team that
discovered P. craigi. He points out that
large areas of the CCZ have already been
designated as reserves, protected from
any future mining. These total 1.44 million
square kilometres, which is almost six times
the size of the UK.
Research into the effects of mining across
the CCZ is ongoing. In the next few years,
Glover and Dan Jones of the UK’s National
Oceanography Centre will lead a project –
in which I am also involved – to investigate
what happens when a company tests one
of its nodule-harvesting machines, which
is permitted under current exploration
licences. These machines work like a sort
of underwater vacuum cleaner, sucking up
nodules and stirring up sediment, which
can have effects at least 10 kilometres beyond
the mine site.21
million tonnesAnnual global manganese
consumption (2016)30
million tonnesTotal copper and zinc at all the
world’s known hydrothermal vents31
million tonnesAnnual global land-based
extraction of copper and zincHydrothermal vents
(left) and seamounts
(above) could be
mined for minerals.
Manganese nodules
(above right), found
in abyssal plains, are
also promisingCH
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