One of the new species of worm, a light blue-white colour.

These delicate new species of polychaete worms have been named Ophelina nunnallyi, after one of the science crew Clifton Nunnally © Wiklund et al. 2019

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New species from the abyssal ocean hint at incredible deep sea diversity

It was once thought that very little could survive in the dark depths of the oceans. But the more researchers look, the more they realise that this seemingly inhospitable environment is actually teeming with life.

In a new paper, scientists from the Museum have described 12 new species of marine worm from the depths of Pacific Ocean. This is expected to be the first of many new species, as they suspect there may be hundreds more waiting to be identified.  

This kind of research is vital, as these regions are soon likely to be targeted for deep sea mining.  

The deep sea is defined as any part of the ocean that is deeper that 1,000 metres, and it is vast. Thought to cover some 60% of the Earth's surface, it is the largest single environment on the planet.

While this environment contains rocky mounts, canyons and hydrothermal vents, the majority is made up of the endless, muddy abyssal plains.

With no light, frigid temperatures and little food making it from the surface thousands of metres above, it has long been thought that these plains were effectively lifeless. Now research is showing us that this is far from the case.

Dr Adrian Glover is a deep sea researcher at the Museum and co-author of a paper describing a dozen new species from these depths, published in the journal Zoo Keys.

'It's astonishing,' says Adrian. 'Over 80% of the animals we bring back up from these abyssal plains are new to science. Maybe higher than that in some instances. This paper we published is one of a series we're slowly producing.'

Mining the depths

The Clarion-Clipperton Zone (CCZ) is a vast area in the Pacific Ocean covering some six million square kilometres between the coasts of Hawaii and Mexico. Averaging a depth of between four and five kilometres the flat, featureless abyssal plain stretches for thousands of kilometres in all directions.

The Clarion Clipperton Zone is a huge expanse of abyssal plains, with much of what is living down there still unknown to science © Craig Smith and Diva Amon, University of Hawaii

But littering this muddy seafloor is something of increasing significance.

'It is one of the most poorly sampled bits of the ocean floor,' says Adrian, 'but there has been a resurgence of interest in the area, led by both national governments and industry, who want to explore it for rare minerals.'

The seafloor in the CCZ is covered with little potato-sized nodules containing minerals such as cobalt, copper, nickel and manganese. These resources are vital for much of the technology we use on a day-to-day basis, and as the electric vehicles and battery storage industry grows the need for these minerals is only expected to rise.

The problems manifest in the fact that very little is known about these environments or what lives there, and so it is difficult to know what impact that mining may have on them.

In charge of regulating work in this area is a United Nations body known as the International Seabed Authority. They require anyone who is working in the CCZ to undertake fundamental baseline surveys of the physical, chemical and biological environments.   

Taxonomic lotto

The new specimens were collected over two expeditions to the deep waters of the CCZ as part of these baseline surveys.

To study the animals on the seafloor, the researchers and crew take a sample of the sediments by lowering a coring device into the deep. This means that the ship needs to be able to carry at least 5,000 metres worth of wire.  

One of the new species of deepsea worms, red and bulbous.

This rather bulbous worm (top) has been called Travisia zieglerae, named in honour of Amanda Ziegler, who was a member of the science party © Wiklund et al. 2019

When the team started looking through what was coming back to the surface, they knew immediately that the sediments were far more diverse than initially predicted.

They found a huge number and diversity of marine worms known as polychaetes. Ranging in size from a few centimetres to a few millimetres, these invertebrates crawl along and through the sediment in even the deepest parts of the oceans.

'We realised straight away while we were still at sea that the sheer number of new species we were going to have to get through was a lot,' explains Adrian. 'We now think that just of the polychaetes, which are one of the most abundant components of the fauna, we have maybe 300 new species.

'So even though we are quite proud of our 23 new species with 12 new names in this latest paper, it is just a drop in the ocean and we still have a long way to go. We are currently working on three more papers like this.'

With the potential for so many new species, naming them becomes something of a problem. Typically, scientists name new species after what they look like, or where they come from. But with so many polychaete worms all from the abyssal depths, this was never going to work.

A rather hairy new species of polychaete worm.

This hairy worm has been named Oligobregma brasierae after Madeleine Brasier, another member of the science party on board the research ships © Wiklund et al. 2019

So Adrian and his colleagues came up with something of a novel solution.

'On these ships there are a lot of crew members, so as well as around 20 scientists there are typically 20 or 30 other crew members,' says Adrian. 'We thought we'd just randomise all their surnames and then put those into a taxonomic lotto.'

This meant that while some species ended up being named after senior scientists, others were given names after crew members and PhD students. 

Paradoxical plains

The abyssal plains are not how many imagine the deep sea. There are no billowing hydrothermal vents spewing heat and nutrients, no mountains of rock rising from the murk. Just thousands and thousands of kilometres of seemingly endless mud.

One of the most intriguing questions is how such a dark, cold, nutrient-poor environment is so rich in biodiversity.

One of the first aspects to understand is that while to us these ecosystems might seem extreme, in the context of the planet they are anything but. In fact, these huge abyssal plains are one of the most common environments on the planet, with the rocky, reef-like seafloors being astonishingly rare.

New worm that is long and thin, with a slight red-orange tinge.

This new species has been named Ammotrypanella keenan in honour of Edward Keenan, a boatswain who was onboard one of the cruises in 2013 © Wiklund et al. 2019

'There are many competing hypthesies as to why these environments are so biodiverse,' explains Adrian. 'The simplest explanation is that these environments are both insanely big and very old.

'These are huge environments which have been around and relatively stable for a long period of time thus allowing a lot of speciation to happen.'

This means that even if the animals that live there, such as the polychaete worms, can't move about a lot, the simple fact that the environment has existed and remained stable for millions of years means that the worms have diversified into a myriad of different species.

With the race on to exploit these regions of rare minerals, there has never been a greater need to understand exactly what is down there first.