Publication Date:
2020-02-06
Description:
Commercial-scale mining for polymetallic nodules could have a major impact on the deepsea
environment, but the effects of these mining activities on deep-sea ecosystems are very
poorly known. The first commercial test mining for polymetallic nodules was carried out in
1970. Since then a number of small-scale commercial test mining or scientific disturbance
studies have been carried out. Here we evaluate changes in faunal densities and diversity of
benthic communities measured in response to these 11 simulated or test nodule mining disturbances
using meta-analysis techniques. We find that impacts are often severe immediately
after mining, with major negative changes in density and diversity of most groups
occurring. However, in some cases, the mobile fauna and small-sized fauna experienced
less negative impacts over the longer term. At seven sites in the Pacific, multiple surveys
assessed recovery in fauna over periods of up to 26 years. Almost all studies show some
recovery in faunal density and diversity for meiofauna and mobile megafauna, often within
one year. However, very few faunal groups return to baseline or control conditions after two
decades. The effects of polymetallic nodule mining are likely to be long term. Our analyses
show considerable negative biological effects of seafloor nodule mining, even at the small
scale of test mining experiments, although there is variation in sensitivity amongst organisms
of different sizes and functional groups, which have important implications for ecosystem
responses. Unfortunately, many past studies have limitations that reduce their effectiveness in determining responses. We provide recommendations to improve future
mining impact test studies. Further research to assess the effects of test-mining activities
will inform ways to improve mining practices and guide effective environmental management
of mining activities.
Type:
Article
,
PeerReviewed
,
info:eu-repo/semantics/article
Format:
text
DOI:
10.1371/journal.pone.0171750
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