Deep-Sea Mining May Harm Thousands of Species—Before They Are Even Discovered

Vast numbers of creatures remain to be found and described in potential mineral extraction area, study finds

New research by the U.K.’s Natural History Museum, funded by The Pew Charitable Trusts has estimated the number of known and unknown benthic animal species—those that live on or near the seafloor—in the Clarion-Clipperton Zone (CCZ), the world’s largest deep-sea mineral exploration frontier. The study provides the first comprehensive list of known benthic species in the CCZ. It further shows that thousands more species remain either undescribed—that is, they have been observed, but scientists have not determined their names or whether they have been found before in the CCZ or elsewhere—or undiscovered.

The International Seabed Authority (ISA), the intergovernmental organization that regulates all mineral activities in areas beyond the jurisdiction of any country, is negotiating regulations that could enable mining in the CCZ as soon as July 2023. Mining activity in the zone could put more than 400 known benthic species and potentially thousands of as-yet-unknown species at risk. More research into the species that live in the CCZ and how they contribute to the wider ecosystem is urgently needed to ensure that mining activity does not irreparably harm this sensitive and important marine environment.

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The Clarion-Clipperton Zone (CCZ) is an area of the deep sea spanning more than 4.5 million square kilometres (1.7 million square miles)—roughly the width of the continental United States—between Hawaii and Mexico. It is beyond designated exclusive economic zones—ocean areas under the jurisdiction of individual countries. The CCZ is home to some of Earth’s most fascinating species, and new ones are being discovered all the time.

Despite the presence of thousands of undiscovered and undescribed species, 17 contractors are exploring the possibility of mining in the CCZ, with a focus on these highlighted areas.

The CCZ features 13 designated areas of particular environmental interest (APEIs), shown here as shaded boxes, that the International Seabed Authority has set aside as a safeguard to protect a representative proportion of species and habitats that could be affected by seabed mining.

However, this new research has confirmed that most of the CCZ’s known species have not been observed in any APEIs. So the designated APEIs may not protect the species most likely to be affected by potential mining activities in the CCZ.

The Clarion-Clipperton Zone (CCZ) is an area of the deep sea spanning more than 4.5 million square kilometres (1.7 million square miles)—roughly the width of the continental United States—between Hawaii and Mexico. It is beyond designated exclusive economic zones—ocean areas under the jurisdiction of individual countries. The CCZ is home to some of Earth’s most fascinating species, and new ones are being discovered all the time.

Despite the presence of thousands of undiscovered and undescribed species, 17 contractors are exploring the possibility of mining in the CCZ, with a focus on these highlighted areas.

The CCZ features 13 designated areas of particular environmental interest (APEIs), shown here as shaded boxes, that the International Seabed Authority has set aside as a safeguard to protect a representative proportion of species and habitats that could be affected by seabed mining.

However, this new research has confirmed that most of the CCZ’s known species have not been observed in any APEIs. So the designated APEIs may not protect the species most likely to be affected by potential mining activities in the CCZ.

The Clarion-Clipperton Zone (CCZ) is an area of the deep sea spanning more than 4.5 million square kilometres (1.7 million square miles)—roughly the width of the continental United States—between Hawaii and Mexico. It is beyond designated exclusive economic zones—ocean areas under the jurisdiction of individual countries. The CCZ is home to some of Earth’s most fascinating species, and new ones are being discovered all the time.

Despite the presence of thousands of undiscovered and undescribed species, 17 contractors are exploring the possibility of mining in the CCZ, with a focus on these highlighted areas.

The CCZ features 13 designated areas of particular environmental interest (APEIs), shown here as shaded boxes, that the International Seabed Authority has set aside as a safeguard to protect a representative proportion of species and habitats that could be affected by seabed mining.

However, this new research has confirmed that most of the CCZ’s known species have not been observed in any APEIs. So the designated APEIs may not protect the species most likely to be affected by potential mining activities in the CCZ.

With so little data from the APEIs and the areas targeted for mining, how can the ISA, which manages this area on behalf of the global community, be sure that these areas are sufficient to serve their purpose?

To begin to answer this and many other critical questions, researchers from the Natural History Museum, London, analyzed publicly available survey and exploration data on the CCZ. Based on that information, they estimate that between 88% and 92% of benthic species in the zone are still undescribed and thousands more remain undiscovered.

Figure 1 depicts these findings as a “rarefaction curve,” which enables researchers to estimate and visualize the number of undiscovered species. The clear upward trajectory of the curve shows that thousands of benthic species have yet to be discovered and that significantly more sampling is needed to find and describe them.

Each New Sample Finds More Species, Suggesting Thousands Remain to Be Discovered and Described: Observed and predicted number of benthic species in the Clarion-Clipperton Zone

The findings of this new study provide further evidence of the significance of the CCZ—and the deep sea broadly—for ocean biodiversity. In addition to the many thousands of benthic species that remain undiscovered in the zone, the data shows that 42% of known deep-sea species were first found in the CCZ. These discoveries, and those yet to be made, highlight the critical need to protect this unique and important region of the global ocean.

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Among the species that have been found are fish, such as Chaunacops coloratus, and anemones, including the Relicanthus species.

Chaunacops coloratus is a rare deep-sea anglerfish. Some observations suggest that they are blue when small and then turn red as they age. They generally walk along the seabed on their fins, except when they are trying to escape a predator, in which case they swim upward very fast.

The Relicanthus species, a massive sea anemone, was discovered 50 years ago, but its relationship to other anemones continues to puzzle scientists.

The Psychropotes dyscrita, a type of sea cucumber also known as a “gummy squirrel,” and the Bathyeliasona mariaae, a variety of deep-sea worm, are two CCZ species. Like most benthic species, they have been found only a handful of times, according to publicly available data.

Bathyeliasona mariaae has only been recorded in the eastern CCZ. If this species is indeed found only in a few locations, then it would be at greater risk of harm from seabed mining, including becoming locally, or even globally, extinct. And this risk is not unique to this species: The study reports that over 37% of known benthic species have been observed only once.

Among the species that have been found are fish, such as Chaunacops coloratus, and anemones, including the Relicanthus species.

Chaunacops coloratus is a rare deep-sea anglerfish. Some observations suggest that they are blue when small and then turn red as they age. They generally walk along the seabed on their fins, except when they are trying to escape a predator, in which case they swim upward very fast.

The Relicanthus species, a massive sea anemone, was discovered 50 years ago, but its relationship to other anemones continues to puzzle scientists.

The Psychropotes dyscrita, a type of sea cucumber also known as a “gummy squirrel,” and the Bathyeliasona mariaae, a variety of deep-sea worm, are two CCZ species. Like most benthic species, they have been found only a handful of times, according to publicly available data.

Bathyeliasona mariaae has only been recorded in the eastern CCZ. If this species is indeed found only in a few locations, then it would be at greater risk of harm from seabed mining, including becoming locally, or even globally, extinct. And this risk is not unique to this species: The study reports that over 37% of known benthic species have been observed only once.

Among the species that have been found are fish, such as Chaunacops coloratus, and anemones, including the Relicanthus species.

Chaunacops coloratus is a rare deep-sea anglerfish. Some observations suggest that they are blue when small and then turn red as they age. They generally walk along the seabed on their fins, except when they are trying to escape a predator, in which case they swim upward very fast.

The Relicanthus species, a massive sea anemone, was discovered 50 years ago, but its relationship to other anemones continues to puzzle scientists.

The Psychropotes dyscrita, a type of sea cucumber also known as a “gummy squirrel,” and the Bathyeliasona mariaae, a variety of deep-sea worm, are two CCZ species. Like most benthic species, they have been found only a handful of times, according to publicly available data.

Bathyeliasona mariaae has only been recorded in the eastern CCZ. If this species is indeed found only in a few locations, then it would be at greater risk of harm from seabed mining, including becoming locally, or even globally, extinct. And this risk is not unique to this species: The study reports that over 37% of known benthic species have been observed only once.

The results of this new study clearly show that decision makers and scientists still do not know nearly enough about which species live at the bottom of the CCZ, how big their populations are, or how each species contributes to the wider ecosystem. Without this information, it will not be possible to accurately predict or assess the environmental impacts of seabed mining activities. The International Seabed Authority must not let mining take place unless sufficient scientific information is available to ensure the marine environment’s protection—no matter how long that takes. These findings make clear that far more research is needed before any regulations can be developed that would effectively manage extractive activity in this remarkable part of the ocean.

This visualization is based on the paper “How many metazoan species live in the world’s largest mineral exploration region?” written by Muriel Rabone et al. and published in Current Biology in May 2023. Chris Pickens of Pew spearheaded the conversion of this paper into this data visualization.