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NATURE GEOSCIENCE | ADVANCE ONLINE PUBLICATION | www.nature.com/naturegeoscience 1
correspondence
To the Editor — e emerging deep-sea
mining industry is seen by some to be
an engine for economic development in
the maritime sector1. e International
Seabed Authority — the body that
regulates mining activities on the seabed
beyond national jurisdiction — must also
protect the marine environment from
harmful eects that arise from mining2.
e International Seabed Authority is
currently draing a regulatory framework
for deep-sea mining that includes
measures for environmental protection.
Responsible mining increasingly strives
to work with no net loss of biodiversity3.
Financial and regulatory frameworks
commonly require extractive industries
to use a four-tier mitigation hierarchy
to prevent biodiversity loss: in order of
priority, biodiversity loss is to be avoided,
minimized, remediated and — as a last
resort — oset4,5. We argue here that
mining with no net loss of biodiversity
using this mitigation hierarchy in the deep
sea is an unattainable goal.
e rst tier of the mitigation hierarchy
is avoidance. Potentially useful mitigation
strategies in the deep sea include patchwork
extraction, whereby some minerals with
associated fauna are le undisturbed, or
other means to limit the direct mining
footprint. Even so, loss of biodiversity will
be unavoidable because mining directly
destroys habitat and indirectly degrades
large volumes of the water column and
areas of the seabed due to the generation
of sediment plumes that are enriched in
bioavailable metals.
Although biodiversity loss within
mines is inevitable, innovative engineering
design could reduce or minimize some
risks to near- and far-eld biodiversity.
For example, shrouds tted to cutting
equipment might reduce the dispersion
of sediment plumes and the footprint
of plume impacts such as the burial of
organisms. Similarly, vehicle design might
limit compaction of seabed sediments.
Of course, the ecacy of such eorts in
mitigating biodiversity loss would need to
be tested.
Remediation addresses the residual
loss of biodiversity at and around a mine
site aer avoidance and minimization
interventions. In the deep sea, native
species are oen slow to recruit and
recolonize disturbed habitats. Slow
recovery on the scale of decades to
centuries, enormous spatial scales of mines
for certain mineral resources (a single
30-year operation license to mine metal-
rich nodules will involve an area about
the size of Austria6) and the high cost of
working in the deep sea may mean that
remediation is unrealistic7. Further, the
science of deep-sea benthic remediation is
a nascent eld8. It is far from established
that remediation of industrial mine sites
in the deep sea is feasible for any mineral
resource, and we know of no remediation
actions that can be applied to the
water column.
e last resort in the mitigation
hierarchy is in-kind or like-for-like
osets within a biogeographical region.
When osets cannot be located where the
aected biodiversity is found, and where
the aected biodiversity is important for
geographically restricted functions such
as connectivity (as is the case for the deep
sea), in-kind osets are not an appropriate
mitigation strategy9. Out-of-kind osets10,
such as restoring coral reefs in exchange
for loss of deep-sea biodiversity, have been
proposed, but this practice assumes that
loss of largely unknown deep-sea species
and ecosystems is acceptable. We question
this assumption on scientic grounds. e
relationship between any gain in biological
diversity in an out-of-kind setting and
loss of biological diversity in the deep
sea is so ambiguous as to be scientically
meaningless. Further, compensating
biodiversity loss in international waters
with biodiversity gains in national waters
could constitute a transfer of wealth that
runs counter to the Law of the Sea, where
benets from deep seabed mining must
accrue to the international community at
large, as part of the common heritage of
humankind. Given the paucity of other
industrial activities in the deep sea (except
perhaps sheries), it is dicult to imagine
a scenario where averted risk osets10 could
apply; that is, where a mining operation
could avert biodiversity losses from
other activities.
e four-tier mitigation hierarchy used
so oen to minimize biodiversity loss in
terrestrial mining and oshore oil and
gas operations thus fails when applied
to the deep ocean. Residual biodiversity
loss cannot be mitigated through
remediation or osets and the goal of no
net loss of biodiversity is not achievable for
deep-seabed mining. Focus therefore must
be on avoiding and minimizing harm. Most
mining-induced loss of biodiversity in the
deep sea is likely to last forever on human
timescales, given the very slow natural
rates of recovery in aected ecosystems. It
is incumbent on the International Seabed
Authority to communicate to the public the
potentially serious implications of this loss
of biodiversity and ask for a response. ❐
References
1. Blue Growth: Opportunities for Marine and Maritime
Sustainable Growth (European Comission, 2012);
http://dx.doi.org/10.2771/43949
2. Levin, L.A. etal. Mar. Poli cy 74, 245–259 (2016).
3. Rainey, H.J. etal. Oryx 49, 232–238 (2015).
4. Ekstrom, J., Bennun, L. & Mitchell, R. A Cross-sector Guide for
Implementing the Mitigation Hierarchy (Cross Sector Biodiversity
Initiative, 2015).
5. Performance Standard 6: Biodiversity Conservation and
Sustainable Management of Living Natural Res ources
(International Finance Corporation, 2012).
6. Smith, C.R., Levin, L.A., Koslow, A., Tyler, P.A. &
Glover, A.G. in Aquatic Ecosystems: Trends and Global Prospects
(ed. Polunin, N.) 334–349 (Cambridge Univ. Press, 2008).
7. Van Dover, C.L. etal. Mar. P olic y 44, 98–106 (2014).
8. Strömberg, S.M., Lundälv, T. & Goreau, T.J. J.Exp. Mar. Bio. Ecol.
395, 153–161 (2010).
9. Pilgrim, J.D. etal. Conserv. Lett. 6, 376–384 (2013).
10. Guidance Notes to the Standard on Biodiversity Osets (Business
and Biodiversity Osets Program, 2012).
Biodiversity loss from deep-sea mining
The Tu’i Malila vent field in the Lau Basin,
southwest Pacific. Lau Basin foundation species
(Alviniconcha spp. snails, Ifremeria nautilei snails,
and Bathymodiolus septemdierum mussels) live
in diuse flow on the surfaces of metal-rich
sulfide deposits.
KAREN JACOBSEN, IN SITU SCIENCE ILLUSTRATION
2 NATURE GEOSCIENCE | ADVANCE ONLINE PUBLICATION | www.nature.com/naturegeoscience
correspondence
C. L. Van Dover1*, J. A. Ardron2, E. Escobar3,
M. Gianni4, K. M. Gjerde5, A. Jaeckel6,
D. O. B. Jones2, L. A. Levin7, H. J. Niner8,
L. Pendleton1,9, C. R. Smith10, T. Thiele11,
P. J. Turner1, L. Watling12 and P. P. E. Weaver13
1Division of Marine Science and Conservation,
Nicholas School of the Environment, Duke
University, Beaufort, North Carolina 28516, USA.
2National Oceanography Centre, University of
Southampton, Waterfront Campus, European
Way, Southampton SO14 3ZH, UK. 3UNAM
ICML-CU, Biodiversidad y Macroecologia, 04510
Mexico City, Mexico. 4Deep-Sea Conservation
Coalition, Postbus 59681, 1040 LD Amsterdam,
Netherlands. 5IUCN Marine and Polar Programme,
Cambridge, Massachusetts 02138, USA.
6Macquarie Law School and Macquarie Marine
Research Centre, Macquarie University, New
South Wales 2109, Australia. 7Center for Marine
Biodiversity and Conservation, Scripps Institution
of Oceanography, UC San Diego, La Jolla,
California 92093-0218 USA. 8University College
London, Torrens Building, 220 Victoria Square,
Adelaide 5000, Australia. 9Université de Bretagne
Occidentale, UMR6308 AMURE, IUEM, 29280
Plouzané, France. 10Department of Oceanography,
1000 Pope Road, University of Hawaii at Mānoa,
Honolulu, Hawaii 96822 USA. 11Institute of
Global Aairs, London School of Economics,
London WC2A 2AZ, UK. 12Department of Biology,
Edmondson Hall, University of Hawaii at Mānoa,
Honolulu, Hawaii 96822, USA. 13Seascape
Consultants, Romsey SO51 0QA, UK.
*e-mail: clv3@duke.edu
Acknowledgements
Research leading to these ndings was supported by the
National Science Foundation (C.L.V.D.), Pew Charitable
Trusts (C.L.V.D.), International Climate Initiative (GOBI;
C.L.V.D.), Université Occidental de Bretagne and Institut
Universitaire Européen de la Mer (C.L.V.D., L.P.), 7th
EU Framework (MIDAS #603418; J.A.A., D.O.B.J., M.G.,
K.M.G., P.P.E.W.), EU Horizon 2020 (MERCES #689518,
D.O.B.J.) and the J.M. Kaplan Fund (L.A.L.).
Competing interests
C.L.V.D. and L.A.L. received research support from
Nautilus Minerals; C.R.S. received research support from
UK Seabed Resources DevelopmentLimited.
Published online: 26 June 2017