deep-sea research

Insights into the biodiversity of annelids in the world’s largest deep-sea mineral exploration region

This study, published in Biodiversity Data Journal, is an important step in creating field guides for CCZ wildlife, which will help promote sustainable practices and informed decision-making.

The demand for rare raw materials, such as cobalt, is fuelling the exploration of the deep-sea floor for mining. Commercial deep-sea mining is currently prohibited in areas beyond national jurisdiction, but companies are permitted exploratory operations in certain areas to assess their mineral wealth and measure environmental baselines. The Clarion-Clipperton Zone (CCZ) is an area of the Pacific deep-sea floor spanning up to 6 million km², found roughly between Hawaii and Mexico. Currently, it has 17 contracts for mineral exploration covering 1.2 million km². However, despite relatively extensive mineral exploration beginning in the 1960’s, baseline biodiversity knowledge of the region is still severely lacking. Even the most basic scientific question: “What lives there?” has not been fully answered yet.

Annelids found in the Clarion-Clipperton Zone.

In a new paper researchers report on the marine life of the CCZ, focusing on annelid worms. Annelids represent one of the largest group of macroinvertebrates living within the mud covering the sea floor of CCZ, both in terms of number of individuals and the number of species. Data from recent oceanographic cruises enabled researchers from the University of Gothenburg, Sweden and the Natural History Museum London to discover more than 300 species of annelids from around 5000 records. The annelid species, many considered to be new to science, were discovered through employment of traditional morphological approaches and modern molecular techniques. The current study focuses on 129 such species across 22 annelid families. Previously, the authors of this study formalized 18 new species, while altogether reporting on 60 CCZ species, including most recently 6 species in family Lumbrineridae. The lead author Helena Wiklund from University of Gothenburg comments: ‘Taxonomy is the most important knowledge gap we have when studying these unique habitats and the potential impact of mining operations. We need to know what lives there to inform the protection of these ecosystems.”

To further understand the CCZ, scientists sail the Pacific Ocean on research expeditions that employ sampling techniques ranging from the technical, like remote-controlled vehicles that traverse the ocean floor, to the simple, like a sturdy box corer collecting sediment at the bottom.

“Sadly, the soft-bodied annelids are often damaged during the collection and sediment sieving onboard” says annelid taxonomist Lenka Neal from the Natural History Museum London. As a result, the traditional morphological approach is often of limited use when working with the deep-sea specimens, with taxonomists increasingly employing DNA techniques as well.

Over the last decade, scientists have generated a large amount of annelid data. Such data are only of use when made available through publication to the wider scientific community and other stakeholders. “A priority is to make the data are FAIR, or Findable, Accessible, Interoperable and Reusable so it can be redeployed easily, if you’ll excuse the pun, for future analysis” says co-author Muriel Rabone. “The same applies to samples, where accessibility of the specimen vouchers and molecular samples allows for reproducibility and continuation of the work. This is one step of the process. And ultimately, having more robust knowledge can lead to more robust evidence-based environmental policy”.

“More often than not, ecological papers describing biodiversity do not include a list of all the species and specimens used to make the broader ecological inferences, and even more rarely make the specimens and all associated metadata available in a FAIR way. In this study, we have made a significant and time-consuming attempt to do this, in a region of the global oceans where critical policy decisions are being made that could impact the way humanity obtains its resources and manages its environment in a sustainable way,” the researchers write in their paper, which was published in the open-access Biodiversity Data Journal.

The team behind the research hope that this still partial checklist of CCZ annelids, many in too poor state of preservation to be immediately described, is a key step forward towards creating future field guides for the area’s wildlife. Given that mining operations in the area could be imminent with the International Seabed Authority considering applications this year, the use of biological data for environmental management has become more important than ever.

This research was supported by funding from UK Seabed Resources Ltd.

Research article:

Wiklund H, Rabone M, Glover AG, Bribiesca-Contreras G, Drennan R, Stewart ECD, Boolukos CM, King LD, Sherlock E, Smith CR, Dahlgren TG, Neal L (2023) Checklist of newly-vouchered annelid taxa from the Clarion-Clipperton Zone, central Pacific Ocean, based on morphology and genetic delimitation. Biodiversity Data Journal 11: e86921. https://doi.org/10.3897/BDJ.11.e86921

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Smithsonian Expedition Yields a New Species of Deep-Sea Coral

Collected from the deep waters off Puerto Rico, the species is a member of an enigmatic, and threatened, group of corals

When people think about corals, most picture the multi-hued reef-builders that reside in balmy waters off tropical beaches. But not all corals stick to the shallows. For example, most members of the order Antipatharia do not live within 160 feet of the surface. Some even reside at depths deeper than 26,000 feet. Commonly known as black corals due to their ink-colored skeletons, these corals are staples of deep-sea ecosystems around the world.

However, black corals remain enigmatic due to the challenges of studying them in the deep sea. This makes it difficult for scientists to assess how black corals, whose skeletons (which are made out of chitin, the same material that composes an insect’s exoskeleton) are prized components of jewelry, are responding to threats like poaching, ocean acidification and climate change.

“Describing these species is fundamental information to make conservation decisions,” said Jeremy Horowitz, a postdoctoral researcher at the National Museum of Natural History who specializes in studying black corals. “You have to know it before you can protect it.”

Jeremy Horowitz, a postdoctoral researcher in the museum’s invertebrate zoology department, examines a coral specimen during a subsequent expedition off Puerto Rico earlier this year. Credit: Jeremy Horowitz, NMNH

In a paper published this week in the journal ZooKeys, Horowitz and his colleagues at the museum and the University of Puerto Rico described Aphanipathes puertoricoensis, a new species of black coral that sports branching features found in multiple coral groups that diverged roughly 100 million years ago.

The new black coral species was discovered in April 2022 during a joint Smithsonian and National Oceanic and Atmospheric (NOAA) expedition to a stretch of the Caribbean Sea just south of Puerto Rico. Here, the seafloor bottoms out into a network of deep-sea canyons and seamounts that remain largely unexplored.

The expedition, led by research zoologist Andrea Quattrini, the museum’s curator of corals and one of Horowitz’s co-authors on the new paper, aimed to explore some of this abyssal terrain and catalog some of the creatures that reside there. Many of these animals live far deeper than human divers can go. So the researchers deployed a remotely operated unmanned vehicle (ROV) called the Global Explorer to depths as deep as 4,000 feet below the ocean’s surface.

Andrea Quattrini, the expedition’s lead researcher, aboard the *Nancy Foster* research vessel. Image courtesy of Illuminating Biodiversity in Deep Waters of Puerto Rico 2022

Over seven dives, the ROV mapped 180 square nautical miles of the deep-sea floor. It collected a suite of biological samples and hours of footage for the researchers to parse on the research vessel above. They observed ghostly, blob-like predators called tunicates, gangly bristle stars, vibrant comb jellies and tiny crustaceans with fused eyes that live inside glass sponges. They even collected a colony of small invertebrates called bryozoa that had not been collected since a Smithsonian expedition to the Puerto Rico Trench in 1933.

One of the deep-sea anemones observed during the expedition. Image courtesy of Illuminating Biodiversity in Deep Waters of Puerto Rico 2022

They also found a multitude of species new to science. While exploring a canyon nearly 1,200 feet below the surface, the ROV came across a scraggly patch of black coral reminiscent of a deep-sea tumbleweed. As the ROV snipped off one of the coral’s spindly branches, Quattrini sent Horowitz, who was back in Washington, a picture of the coral on the ROV’s live feed. “She shared a picture of this coral and I immediately had no idea what it was,” Horowitz said.

When the expedition’s trove of specimens arrived in Washington, Horowitz could finally take a closer look at the puzzling coral. With long, coiled branches emanating from a short stalk like a tiny tree, the coral sported features found in multiple genera, or groups, of black coral that diverged long ago.

A microscopic close-up of the black coral’s spines taken with the help of the museum’s scanning electron microscope. Credit: Jeremy Horowitz, NMNH

To assign the new species in the right group, Horowitz placed a fragment of the coral specimen underneath a high-powered scanning electron microscope at the museum. That gave him a microscopic view of the miniscule spines that line the coral skeleton. Like a fingerprint, a coral species’ spines have their own distinct shape. Comparing these spines to known black coral species allowed Horowitz to get a better idea of where this new species may slot into the black coral family tree. To be sure, the researchers also used cutting edge techniques to compare the new species’ genetic code with other corals.

All this work allowed the researchers to find a taxonomic home for the new species in the genus Aphanipathes. They christened the black coral with the species name puertoricoensis in homage to the island near where it was found.

Discarded fishing gear sits on a thicket of black coral in the deep sea off of Puerto Rico. Image courtesy of Illuminating Biodiversity in Deep Waters of Puerto Rico 2022

Horowitz believes its resemblance to other groups of black coral reveals how helpful a simple body type is for survival in the deep-sea. “This simple morphological structure is evolving over and over again, probably because the conditions are the same in these different areas,” he said. “This simple structure is what works.”

The team is still examining the specimens collected and expects to name additional new species in the near future. There are also plans to go back and conduct further field research in the deep-sea canyons and ridges off Puerto Rico. “Every time we go back to this region, we find new species,” Horowitz said.

But there is also plenty to uncover closer to home. The piece of black coral from Puerto Rico recently joined the museum’s 4,000 other black coral specimens — the largest such collection in the world. Many of these black coral specimens likely represent undescribed species hiding in plain sight. According to Horowitz, “we don’t even have to go offshore to find new species.”

Reference:

Horowitz J, Opresko DM, González-García MP, Quattrini AM (2023) Description of a new species of black coral in the family Aphanipathidae (Anthozoa, Antipatharia) from Puerto Rico. ZooKeys 1173: 97-110. https://doi.org/10.3897/zookeys.1173.104141

Story originally published by the Smithsonian Magazine. Republished with permission.

DNA study in the Pacific reveals 2000% increase in our knowledge of mollusc biodiversity

Lead author Dr Helena Wiklund examining specimens on the RV Melville in October 2013

Scientists working in the new frontier for deep-sea mining have revealed a remarkable 2000% increase in our knowledge of the biodiversity of seafloor molluscs.

The 21 mollusc species newly described thanks to the latest DNA-taxonomy methodology

Tweny-one species, where only one was previously known, are reported as a result of the research which applied the latest DNA-taxonomy methodology to mollusc specimens collected from the central Pacific Clarion Clipperton Zone (CCZ) in 2013. They are all described in the open access journal ZooKeys.

Among the discoveries is a monoplacophoran mollusc species regarded as a ‘living fossil’, since it is one the ancestors of all molluscs. This is the first DNA to be collected from this species and the first record of it from the CCZ mining exploration zone – a vast 5-million-km² region of the central Pacific that is regulated for seabed mining by the International Seabed Authority.

“Despite over 100 survey expeditions to the region over 40 years of mineral prospecting, there has been almost no taxonomy done on the molluscs from this area,” says lead author Dr Helena Wiklund of the The Natural History Museum in London (NHM).

Dr Wiklund undertook a comprehensive DNA-based study of the molluscs to confirm species identities and make data available for future taxonomic study. This was coupled with the expertise of the NHM’s Dr John Taylor, who led the morphological work.

The molluscs were found in samples taken on and in the mud surrounding the potato-sized polymetallic nodules that are present in high abundance across the CCZ. These nodules are the target for potential deep-sea mining being rich in cobalt, copper, nickel, manganese and other valuable minerals.

The data are vital for the future environmental regulation of deep-sea mining, but have also revealed surprising patterns.

“I was amazed to discover that specimens collected during the 19th century by HMS Challenger were probably the same as ours over a range of 7000 km, but that data lodged on genetic databases from closer but shallower depths is likely to be from a different species,” comments Dr Thomas Dahlgren, population geneticist at Uni Research, Norway and University of Gothenburg, Sweden, who studied in detail a species called Nucula profundorum.

“Our efforts are now focussing on studying the DNA from many more samples of this species to examine connectivity and potential resilience to deep-sea mining,” he added.

Dr Thomas Dahlgren sieving sediments to find new clam and snail species

“It is a simple truth that we cannot move forward on regulatory approval for deep-sea mining without fundamental baseline data on what animals actually live in these regions,” says Principal Investigator of the NHM Deep-sea Systematics and Ecology Research Group, Dr Adrian Glover.

“Our work has highlighted obvious gaps in our knowledge, but also shown that with even relatively modest effort, we can greatly increase our understanding of baseline biodiversity using DNA-taxonomy.”

Creating a library of archived DNA-sequenced samples from known species allows for the future possibility of using the latest environmental DNA (eDNA) methods to ‘search’ for these species using just tiny samples of mud or seawater.

“Its akin to forensic science’, says Dr Glover. “You can’t use eDNA to find the criminals or species unless you have a library of information to compare them too”.

All data and specimens from the study have been lodged at the NHM and online repositories to make them accessible for future study. Of particular importance are the frozen tissue collections, which are housed in the state-of-the-art Molecular Collections Facility at the NHM and available for loan or further DNA work.

Original source:

Wiklund H, Taylor JD, Dahlgren TG, Todt C, Ikebe C, Rabone M, Glover AG (2017) Abyssal fauna of the UK-1 polymetallic nodule exploration area, Clarion-Clipperton Zone, central Pacific Ocean: Mollusca. ZooKeys 707: 1–46. https://doi.org/10.3897/zookeys.707.13042