NOC: Environmental Impact of Deep-Sea Mining can Last Decades

Unique deep-sea hydrothermal vent ecosystems that harbour chemosynthetic life forms such as giant tubeworms. Active mining of vents would destroy these rare ecosystems (Image: NOAA Okeanos Explorer Program)

Maritime Executive | 30 May 2019

A new study shows that the impacts of seabed mining on deep-sea ecosystems can persist for decades. 

Scientists at the U.K.’s National Oceanography Centre (NOC) revisited a site exposed to deep-sea mining activity nearly 30 years previously to assess seabed and ecosystem recovery. They used a robot submarine to map and photograph much of the seafloor in the disturbed area in unprecedented detail. The images were combined into a seafloor photo-mosaic completely covering 11 hectares of seabed, the largest ever photo-mosaic obtained in the abyssal ocean. Tracks on the seafloor caused by the simulated mining were still clearly visible, and the impacts on marine life initially observed in 1989 persist.  

The study, recently published in Scientific Reports, was able to pinpoint individual animals over a wide area and relate their abundance and distribution to the tracks. While mobile species, such as sea cucumbers and sea stars, were able to recolonize impacted areas, many animals, such as sponges and sea anemones, live attached to the seafloor and remained virtually absent from directly disturbed seabed. Given the important role of these animals in abyssal ecosystems, the results of the study suggest that impacts of large-scale commercial mining could potentially lead to an irreversible loss of key ecosystem functions, says the NOC.

The target of this type of deep-sea mining is polymetallic nodules, potato-shaped rocks rich in copper and manganese. These nodules provide a stable anchoring point for the development of anemones, soft corals and sponges, and promote the development of diverse communities on otherwise muddy seabed. The nodules take millions of years to form. Removal or burial of nodules from mining activities will remove the home of many of these filter-feeding animals, constraining their capacity to recolonize impacted zones and further delaying ecosystem recovery processes. 

The site investigated lies in the deep Pacific Ocean off Peru at around 4,000 meters water depth. It was disturbed as an experiment in 1989 by a team of German researchers. This is still to date the largest disturbance experiment carried out in an abyssal environment. 

The study is the result of a collaboration between the NOC and the GEOMAR institute in Kiel (Germany) funded by the European Union Joint Programming Initiative (JPI-Oceans), an international project aiming to assess the ecological aspects of deep-sea mining. The NOC is working with the U.K. Government and the International Seabed Authority to inform developing regulations regarding deep-sea mining.

1 Comment

Filed under Environmental impact, Pacific region, Papua New Guinea

One response to “NOC: Environmental Impact of Deep-Sea Mining can Last Decades

  1. Richard Manfredi

    Photo mosaic, in English it is a doctored picture. Tracks from SIMULATED MINING were clearly visible; simulated tracks means more fake. So, sponges and sea anemones remained VIRTUALLY absent . In english, not as many as before , but recolonized. How fast do sponges and sea anemones grow? How do they spread from here to there? Will deep sea mining leave rocks on the sea bed floor after mining?Can sponges and sea anemones use them? All of this from a 1989 experiment at 4000 meters.This is a thirty year ( 2019 less1989 ) boondoggle.
    What you need is some current pictures of areas , before and after mining.Then come back five, ten, twenty and thirty years later and do a comparison .
    If you have a legitimate concern, you could mine areas in rows, or a checkerboard pattern. The ocean currents will send the rare sea sponges and anemones to new homes.
    What will you do if the habitat is so improved the mined areas are better than the originals?
    in this hit piece , you forgot the rare bacterial lifeforms that live around the vents.
    Could there be more volcanic chimney vents as the volcanic pressure would not have to penetrate so much ocean floor?
    Would you be able to “harvest’ the same area twice after some short time period ?

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