Science

Scientists discover five new species of black corals living thousands of feet below the ocean surface near the Great Barrier Reef – Raw Story

The Research Brief is a short summary of interesting academic work.

The big idea

Using a remote-controlled submarine, my colleagues and I discovered five new species of black corals living as deep as 760 meters below the surface in the Great Barrier Reef and Coral Sea off the coast of Australia.

Black corals grow in both shallow waters and to depths greater than 26,000 feet (8,000 meters), and some individual corals can live more than 4,000 years. Many of these corals are branched and look like feathers, fans or bushes, while others are straight like a whip. Unlike their colorful shallow-water cousins ​​that rely on the sun and photosynthesis for energy, black corals are filter feeders and eat small zooplankton that are abundant in deep waters.

The team of researchers collected 60 black coral specimens during 31 dives using a remotely operated submarine.

In 2019 and 2020, I and a team of Australian scientists used the Schmidt Ocean Institute’s remotely operated vehicle – a submarine called SuBastian – to explore the Great Barrier Reef and Coral Sea. Our goal was to collect samples from coral species that live in waters 130 feet to 6,000 feet (40 meters to 1,800 meters) deep. In the past, corals from the deep parts of this region were collected using dredging and trawling methods that often destroyed the corals.

Our two expeditions were the first to send a robot to these specific deep-water ecosystems, allowing our team to actually see and safely collect deep-sea corals in their natural habitat. Over the course of 31 dives, my colleagues and I collected 60 specimens of black coral. We carefully removed the corals from the sandy bottom or coral wall using the rover’s robotic claws, placed the corals in a pressurized, temperature-controlled storage box, and then raised them to the surface. We would then examine the physical characteristics of the corals and sequence their DNA.

Among the many interesting specimens were five new species — including one we found growing on the scale of a nautilus more than 2,500 feet (760 meters) below the ocean’s surface.

Researchers used their rover’s robotic arm to collect more than 100 samples of rare corals and brought them to the surface for further study. Jeremy Horowitz, CC BY-ND

Why it matters

Like shallow water corals that build colorful reefs teeming with fish, black corals act as important habitats where fish and invertebrates feed and hide from predators in what is otherwise a largely barren seabed. For example, a single black coral colony that researchers collected off the coast of California in 2005 was home to 2,554 individual invertebrates.

Recent research is beginning to paint a picture of a deep sea that contains many more species than biologists previously thought. Since there are only 300 known species of black corals in the world, finding five new species in one general location was very surprising and exciting for our team. Many black corals are threatened by illegal harvesting for jewelry. To smartly conserve these fascinating and hard-to-reach habitats, it is important for researchers to know which species live at these depths and the geographic ranges of individual species.

A large, white, tree-like coral underwater.

Black corals don’t form large reefs like shallow corals, but individuals can grow quite large – like this one Antipathes dendrochristos found off the coast of California – and act as a habitat for thousands of other organisms. Mark Amend/NOAA via Wikimedia Commons

What is not yet known

Every time scientists explore the deep sea, they discover new species. Simply exploring more is the best researchers can do to fill knowledge gaps about what species live there and how they are distributed.

Because so few specimens of pelagic black corals have been collected and there are likely so many undiscovered species, there is also much to learn about the evolutionary tree of corals. The more species biologists discover, the better we can understand their evolutionary history, including how they survived at least four mass extinctions.

What’s next

The next step for my colleagues and me is to continue exploring the ocean’s seabed. Researchers have yet to collect DNA from most known species of black corals. In future expeditions, my colleagues and I plan to return to other deep reefs in the Great Barrier Reef and Coral Sea to learn more about and better protect these habitats.The conversation

Jeremy Horowitz, postdoctoral researcher in invertebrate zoology, Smithsonian Institution

This article is republished from The Conversation under a Creative Commons license. Read the original article.

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