Scientists Discover 28 New Species and the World's Largest Cold-Water Coral Reef off Argentina's Coast

Elementary

A deep-sea expedition off the coast of Argentina has produced one of the most exciting ocean discoveries of recent years. Scientists aboard the R/V Falkor, operated by the Schmidt Ocean Institute, spent weeks mapping the seabed from Buenos Aires south to Tierra del Fuego. They returned with evidence of 28 species that are completely new to science.

Among the most remarkable findings was a giant cold-water coral reef. Made up of a white coral species called Bathelia candida, the reef covers an area roughly equal to Vatican City -- about 0.4 square kilometres. Scientists believe it is the largest cold-water coral reef ever found anywhere on Earth.

The team also filmed a phantom jellyfish known as Stygiomedusa gigantea, one of the ocean's most mysterious creatures. Because it lives at depths of more than a thousand metres, sightings are extremely rare. Only a small number of encounters with this jellyfish have ever been recorded.

Perhaps the most striking discovery was a deep-sea whale fall -- the skeleton of a large whale resting on the seafloor at a depth of about 3.8 kilometres. Hundreds of small creatures were feeding on it. It was the first whale fall ever documented in Argentine waters.

remarkable: unusual and worth noticing; impressive

kilometre: a unit of distance equal to one thousand metres

mysterious: difficult to understand or explain; not well known

depth: the distance from the top of something to the bottom

encounter: an unexpected meeting with something or someone

document: to record information about something officially

skeleton: the set of bones that form the structure of a body

richer: having more of something, such as variety or resources

Intermediate

An oceanographic expedition along Argentina's Patagonian margin has yielded a cascade of record-breaking discoveries, including 28 species new to science and what researchers are calling the world's largest known cold-water coral reef structure.

The survey was conducted aboard the R/V Falkor, a research vessel operated by the Schmidt Ocean Institute and equipped with remotely operated vehicles capable of reaching depths beyond 4,500 metres. Over several weeks, the ship traversed the deep-water slope from Buenos Aires to Tierra del Fuego, collecting specimens and footage from habitats that had never been scientifically sampled.

The headline discovery is a sprawling reef built almost entirely from Bathelia candida, a white branching coral that thrives in cold, nutrient-rich waters below 200 metres. The reef extends across approximately 0.4 square kilometres -- an area comparable to Vatican City -- making it the largest cold-water coral reef on record. Cold-water coral ecosystems are ecologically significant because they provide habitat for hundreds of invertebrate species and act as slow-growing carbon sinks.

The expedition also documented a living specimen of Stygiomedusa gigantea, the so-called phantom jellyfish, and located a whale fall at approximately 3.8 kilometres below the surface. The whale fall -- a dead cetacean whose skeleton was supporting a dense community of specialised scavengers -- was the first ever confirmed in Argentine waters, providing scientists with a valuable window into how nutrients cycle through the deep-sea ecosystem.

margin: the underwater slope at the edge of a continent, connecting the shallow shelf to the deep ocean floor

remotely operated vehicle: an unmanned underwater robot controlled from a ship, used to explore the deep ocean

specimen: an individual plant, animal, or object collected for scientific study

invertebrate: an animal without a backbone or spinal column, such as a jellyfish, worm, or coral

carbon sink: a natural system that absorbs more carbon dioxide from the atmosphere than it releases

cetacean: a member of the group of large sea mammals that includes whales, dolphins, and porpoises

scavenger: an animal that feeds on dead animals or organic waste material

biodiversity: the variety of plant and animal life found in a particular habitat or on Earth as a whole

Advanced

A comprehensive deep-sea survey of Argentina's Patagonian continental margin has produced what scientists are describing as among the most consequential benthic discoveries of the decade, encompassing 28 previously undescribed species, a record-setting cold-water coral bioherm, a confirmed sighting of one of the ocean's most elusive invertebrates, and the first documented whale fall in Argentine territorial waters.

The three-week expedition was mounted aboard the R/V Falkor, the Schmidt Ocean Institute's research vessel, and was led by Dr. Maria Emilia Bravo, a marine benthic ecologist at the University of Buenos Aires. Equipped with a remotely operated vehicle rated to 4,500 metres, the team conducted systematic transects from the outer continental shelf near Buenos Aires southward to the deep abyssal slopes off Tierra del Fuego, covering habitats that had seen no prior scientific sampling.

The pre-eminent structural discovery is a cold-water coral bioherm dominated by Bathelia candida, a branching scleractinian coral characteristic of the bathyal zone between 200 and 2,000 metres. The bioherm's footprint spans approximately 0.4 square kilometres -- a surface area comparable to Vatican City and substantially larger than any previously measured cold-water coral structure on record. Framework-building cold-water corals are considered ecosystem engineers: their three-dimensional architecture supports hundreds of associated invertebrate taxa and functions as an organic carbon repository at timescales of centuries to millennia.

The expedition also produced footage of Stygiomedusa gigantea, the phantom jellyfish, which has been recorded fewer than 150 times since its formal description in 1910. At approximately 3,850 metres below the surface, the team documented an advanced-stage whale fall dominated by a dense assemblage of Osedax bone-eating polychaete worms and sulfide-oxidising chemosynthetic bacteria -- Argentina's first confirmed whale fall, providing evidence that deep chemoautotrophic communities are broadly distributed along the Southwest Atlantic margin. The 28 new species, spanning cnidarians, echinoderms, polychaetes, and amphipods, have been deposited with the Argentine Museum of Natural Sciences for formal taxonomic description.

benthic: relating to the bottom of a body of water and the organisms that live there

bioherm: a reef-like mound or structure built up by sedentary organisms such as corals

scleractinian: belonging to the order of stony corals that build calcium carbonate skeletons and form reef structures

bathyal zone: the ocean zone between 200 and 2,000 metres depth, below the photic zone but above the abyssal plain

transect: a straight line or path along which observations are systematically made to survey an area

chemoautotrophic: describing organisms that produce organic compounds using chemical energy rather than sunlight

polychaete: a class of segmented marine worms, many of which live in ocean sediments

taxonomic: relating to the science of classifying organisms into groups based on shared characteristics

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Scientists Discover 28 New Species and the World's Largest Cold-Water Coral Reef off Argentina's Coast

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