A light illuminates the abyssal plain 5,000 metres below the ocean surface revealing an alien-looking crature. It has a single long stalk projecting up from the seafloor finishing in a spiked ball-like structure.

At first glance the abyssal plain might not look like much, but it is teeming with life unlike anything found anywhere else on Earth ©SMARTEX Project/smartexccz.org


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Around 90% of species in proposed deep-sea mining zone are unnamed

Many regions of the deep sea are currently being explored for the potential to mine them for minerals, but it is still largely unknown what actually lives on the seabed.

Two new papers have looked at all the published records for the species found in one of these zones, and found that its sea floor is likely far more diverse than realised. They estimate that between 6,000-8,000 species are waiting to be discovered, but also note that this is likely an underestimate. 

The Clarion-Clipperton Zone (CCZ) is a huge area of the Pacific Ocean located between Hawaii and Mexico. A deep sea abyssal plain, the CCZ would be unremarkable in many respects, except for one thing: it is scattered with nodules of highly valuable minerals.

These nodules are aggregates of minerals such as iron and manganese hydroxides, materials that are predicted to be in increasingly high demand as the global shift to green technology intensifies over the coming decade.

Because of the high concentration of these nodules in the CCZ, many regions are being explored for the potential to mine them, by sending down autonomous rovers that will scoop up the sediment and nodules and transport them to the surface. One of the main concerns is that mining activity would destroy this fragile ecosystem that has been likely been persisting unchanged for millions of years.

This has led to a flurry of activity to try and understand what is actually down there, and how the ecosystem functions before any large-scale activity starts.

A picture of the muddy floor of the CCZ. The foreground is illuminated by the rover, revealing sountless dark nodules scattered randomly across the mud, slowly fading into black in the distance.

The seafloor of the CCZ is strewn with nodules made up of highly valuable minerals, but are also home to countless invertebrates ©SMARTEX Project/smartexccz.org

To try and fill some of these gaps, a team of researchers at the Museum have been delving into the data that has been collected on the wildlife that has been found in the CCZ over the past few decades. What they have found is a range of issues with how this data has been collected and stored by the International Seabed Authority (ISA), which is the organisation responsible for the management of mining operations on the seafloor.

This has potential impacts on how the diversity of these regions is calculated, which in turn has a knock-on effect with how mining in these regions will be granted and regulated. 

Muriel Rabone is a deep-sea researcher at the Museum, who has been looking at the data collected on the CCZ to figure out a baseline of what is and - more crucially - what is not known about the life that lives on the abyssal plain.

'I found some of the data recorded are actually duplicates,' explains Muriel. 'We're talking about at least a quarter of the records, potentially as high as a third.'        

'This is reducing the diversity estimates of species in the CCZ, and this has big implications for the environmental management side of things.'

This analysis has been published in the journal Database, while a second paper which has found that around 90% of all species in the CCZ remain unnamed has now been published in Current Biology, and was funded by the Pew Charitable Trust

A vivid purple sea slug with a long tail-like appendage creeping across a muddy sea floor.

The seafloor is home to a huge range of animals, from sea slugs and polychaete worms to shrimps and fish, but  much of it remains unnamed ©SMARTEX Project/smartexccz.org

What is the Clarion-Clipperton Zone?

The Clarion-Clipperton Zone is a vast muddy plain of roughly 6 million square kilometres stretching between Mexico and Hawaii. To put that into context, it is about the same width as the entire continental United States.

With an average depth of around 5,000 metres, it is one of the most remote and pristine environments on the planet.

At first glance the nodule-strewn mud bathed in eternal darkness might appear inhospitable. But look a little closer and it is teeming with life, from tiny, hairy worms burrowing through the sediment, to ghostly white sea anemones drifting on the current and deep-purple sea cucumbers sauntering along the bottom.

The life that can be found thriving in these frigid waters of the deep is a surprisingly diverse, including a whole range of worms, sponges, starfish, crustaceans and even the odd fish.

It is likely that the sheer diversity of this abyssal plain is related to its extraordinary age and the fact that the conditions have remained largely unchanged throughout this entire time, giving species literally millions of years to diversify. 

So how many species live in the CCZ?

Despite this apparent extraordinary biodiversity, very little is known about what is actually down there. Over the past few decades there have been multiple surveys of the region by mining contractors, scientific institutes, and governments.

These have collected thousands of individual specimens from the CCZ, but a shocking number of these remain unidentified, and potentially new to science.

The second paper by Muriel and her colleagues have attempted to answer the question of species diversity, in effect doing a stocktake of what specimens have been collected, what species these represent, and what still needs to be figured out. 

A series of alien-looking specimens from the CCZ in glass jars on a bench in the lab.

While thousands of specimens have been collected from the CCZ, only a few hundred have actually been identified to a species level ©The Trustees of the Natural History Museum, London

'There are 438 named, known species from the CCZ,' explains Muriel. 'But then there are 5,142 unnamed species, with informal names.'

'These are species that haven't been described yet, meaning we might know the genus, but can't identify the species. It is actually a lot more than I thought.'

While some of these might belong to species that have already been described from the region but are simply unidentified, it seems likely that most of them will be  entirely new species altogether.

'But based on the data, we would predict there are between 6000-8000 more unknown animal species down there,' says Muriel. 'This means that around 90% of species are not known to science.'

This is a huge percentage, but it is important to note that this is about the same for the oceans as a whole. The significant difference here is that the abyssal plains are being actively explored for mineral extraction before we fully understand what is living there. 

Dr Adrian Glover, a Merit Researcher at the Museum and co-author of both the studies, says, 'Taxonomy is the most important knowledge gap we have when studying these unique habitats. We have to know what lives in these regions before we can begin to understand how to protect such ecosystems.'

'Exploration for the minerals to create green technologies is not going away. It is imperative that we work with the companies looking to mine these resources to ensure any such activity is done in a way that limits its impact upon the natural world. DeepData is a major step in the right direction and its vital that all stakeholders support the ISA in this endeavour.'

Scientists on a research boat sift through the mud collected from the bottom of the ocean.

The CCZ is one of the best studied areas of the deepsea, and yet we still know relatively little about it ©SMARTEX Project/smartexccz.org

Effective management needs better data

The concern now is that knowing the species that live there is really only the very first step in understanding the ecosystem as a whole, and even then taxonomy has not been prioritised when it should have been.

'In a way I am surprised about how little we actually know,' says Muriel. 'Considering we have been visiting the CCZ since the 1960s, and it is actually the best-known abyssal region, yet we still know only 10% of species level diversity.'

'And that is just the tip of the iceberg. Because that doesn't tell us what the ecosystem functioning is, it doesn't tell us what the connectivity is.'

These factors will be key when looking at how disruptive industries might affect the communities of organisms living down there. For example, if we don't know how connected one part of the CCZ is to another, we have no idea how or if species will be able to move out of mining zones into protected areas.  

Based on the findings from these papers, the researchers have set out a number of recommendations for how to now move forward. The first step would be fully utilise the global biodiversity database known as Darwin Core, but also include cleaning up the data that already exists and ensuring that any new data added is cross referenced with other species databases to make sure it is as accurate as possible.

It is hoped that this will mean any future decisions made about the CCZ will be done on more solid foundations.