Mining, Metals and Megafauna in the Pacific Deep-Sea

DivaAmon Contributed by Diva Amon

I’m a deep-sea biologist with an ethical conundrum: I get to work in one of the most poorly-known habitats on the planet but the only reason I have that privilege is because it will likely be exploited and irreparably altered within the next decade.

We rarely think about where the never-ending stream of resources that we consume comes from. Take for instance the iPhone 6S you upgraded to when nothing was wrong with iPhone 5, or that zero-emission electric car you just bought: do you know where the materials used to make those came from? The demand for metals is increasing worldwide resulting in resources being harvested in ever more remote places, and the next frontier of mining will likely take place in the deep ocean.


Figure 1. Polymetallic nodules of various sizes. Image credit: Diva Amon.

My research takes place in the Clarion-Clipperton Zone (CCZ), an abyssal region (3500-5500 m) in the tropical Pacific Ocean that stretches from Hawaii to Mexico. The CCZ has dense beds of polymetallic nodules: lumps of metallic ore laden with cobalt, copper, nickel and other rare metals that sit like cobbles on a street. It is thought that they form in a similar way to a pearl (accretion) at a rate of a few millimeters per million years. As this entire region is in international waters, it falls under the mandate of the International Seabed Authority (ISA) and so far, there have been 15 mining exploration areas allocated, each up to 75,000 km2 or roughly the size of Panama.

ISA map

Figure 2. Exploration claim areas in the CCZ. Downloaded from the ISA website.

Let’s be honest, nodule mining is going to do some damage. Nodules will be harvested, destroying all animals that rely on this habitat and leaving no possibility for the re-establishment of this community in the future. Machines will also likely disturb and compact large swathes of sediment >5 m wide and 5-20 cm deep, squashing air out of the sediment (removing crucial living space for animals) as well as directly killing any animals residing in or on the sediment. Huge sediment plumes will also be kicked up, which will travel for kilometers before depositing elsewhere, potentially stifling animals and blocking filter-feeding apparatuses. Further entombment of the seafloor will likely occur when tailings are discharged into the water column. Not to mention other possible impacts that include light and noise pollution from machinery, and major changes to the geochemistry of the sediment, food webs (with repercussions for fisheries), and carbon sequestration. The cumulative impacts of these operations aren’t yet understood but will likely be long-standing and ocean-wide.

Oebius mining method

Figure 3. The polymetallic-nodule mining concept taken from Oebius et al 2001.

Despite this looming threat, the CCZ is critically underexplored. We literally do not even know what lives there. The ISA has made it mandatory that contractors undertake a baseline study of the biology living at the seafloor before EIAs and mining can begin.  The ABYSSLINE Project, which I work on, is doing just that in the claim area leased to UK Seabed Resources Ltd (UKSRL). My task is to find out what megafauna (the awesome charismatic animals over 2cm in size) live in the UKSRL claim, how abundant and diverse they are, and what ranges they occupy, not only within the claim but also across the entire CCZ. It’s also crucial to find out whether variations in the megafauna community correlate with nodule presence and other environmental parameters.

Although it is still early days for the project and there are still many more years of work to do, preliminary results show that the UKSRL claim area is rich not only in metals but also in life. Our first expedition sampled a 30 x 30 km area of the UKSRL claim using a remotely operated vehicle and various other pieces of equipment. There was life everywhere: tiny white corals, pink and purple sea cucumbers, bright red shrimp and strange unicellular animals that create sedimented homes the size of your fist.  In this relatively small area, we saw 170 megafauna morphotypes and it’s likely that’s an underestimate! These levels of biodiversity are the highest in the CCZ and are comparable to many other abyssal regions worldwide. We also collected 12 megafauna morphotypes and half of those were new to science including some of the most commonly seen, reiterating how little we know of the abyssal life in this region.


Figure 4. Some of the rare and unique megafauna that call the CCZ home. Image credit: Diva Amon and Craig Smith, University of Hawaii at Manoa. Collage created by Amanda Ziegler.

We’ve seen so many incredible animals in the CCZ and it can suck when you think about what will likely happen in the future. But when I feel that sinking feeling inside, I find the strength to continue by remembering why we are doing this work. We can’t manage what we don’t understand and we can’t protect what we don’t know. If deep-sea mining is to go ahead in the CCZ, high-quality scientific work needs to be done to establish the full extent to which animals will be impacted and how best to mitigate these effects and balance the needs of both society and nature.

Diva Amon is a postdoctoral scholar in the Smith Lab at the Department of Oceanography at the University of Hawaii at Manoa. She is a deep-sea ecologist with a special interest in chemosynthetic habitats and anthropogenic impacts in the deep sea. Her current research is focused on understanding what megafauna inhabit the largely unknown deep sea of the Clarion-Clipperton Zone in the Pacific Ocean, in advance of the mining of this region for polymetallic nodules. She considers herself to be a ‘tropical species’ having been born and raised in Trinidad and Tobago and so has adjusted to life in Hawai’i quickly. You can find her on Twitter as @DivaAmon.  


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