The deepest photosynthesising coral in the world and 160 species – at least 50 of which are believed to be new to science – observed during a deep-sea expedition at Chile’s Salas y Gómez Ridge.

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Published: Friday, 12 April 2024 at 09:30 AM


Scientists have spotted the deepest known photosynthesising coral – a Leptoseris, also known as a wrinkle coral – at the Salas y Gómez Ridge off the coast of Chile.

During the same expedition onboard the Schmidt Ocean Institute’s R/V Falkor (too), they also found at least 50 species that might be new to science. 

The researchers collected wrinkle corals from three sites: an unnamed seamount (176 metres deep), Pukao seamount (182m) and Motu Motiro Hiva (197m) – 15m deeper than it had previously been found.

“Basically, at these depths, the ROV pilots could turn off all ROV lights and still have light to see with the whole environment appearing in different shades of blue to black, especially if they adjusted the camera ISO settings,” says Chief Scientist Dr. Erin E. Easton of the University of Texas Rio Grande Valley.

The deepest-known photosynthesis-dependent Leptoseris coral, seen on the northern flank of Motu Motiro Hiva, an uninhabited island off the coast of Chile. Credit: ROV SuBastian / Schmidt Ocean Institute

Corals are animals that have a mutually beneficial relationship with a type of algae called Zooxanthellae.

The algae live inside the tissue of the coral polyp for protection and, in return, provide their host with nutrients which they create through photosynthesis – a bit like if you let a friend stay at your house if they promised to cook you dinner every day (and maybe redecorate: Zooxanthellae are also the reason corals are brightly coloured). 

Squat lobster in a coral garden on the southwestern flank of Rapa Nui
A squat lobster in a coral garden located on the southwestern flank of Rapa Nui. Credit: ROV SuBastian / Schmidt Ocean Institute

The Salas y Gómez Ridge is not just a haven for these corals but is rich in biodiversity, which can quickly change in just metres.

“It is like driving down a dark street at night, making a turn, and seeing a whole different world,” says Easton.

Chaunax documented on the southwestern flank of Rapa Nu
A chaunax (genus of bony fish in the sea toad family) documented on the southwestern flank of Rapa Nui. Credit: ROV SuBastian / Schmidt Ocean Institute

During the expedition, scientists observed 160 species – including squid, fish, corals, molluscs, sea stars, sea urchins, crabs and squat lobsters – with 50 of those likely to be new to science.

The high number of potential new, endemic species might be to do with the isolated nature of the chain of seamounts. “Connectivity among seamounts could be more limited, allowing time for species to evolve in isolation,” explains Easton. 

“The environmental conditions change notably over its range,” she adds – the region is high-nutrient and low oxygen in the east and ultra-low nutrients and high oxygen in the west – “possibly leading to evolutionary changes and evolution of new species over geologic time.” 

Bathyphysa siphonophore
A bathyphysa siphonophore spotted during an exploration transect on the southeastern flank of an unexplored seamount located east of Motu Motiro Hiva. Credit: ROV SuBastian / Schmidt Ocean Institute

Gathering data on the many different animals living in this region – which is also important for migratory species, such as sharks, tuna and whales – is important in supporting the management and potential expansion of marine protected areas, in particular around Rapa Nui.

“Discovering new species, and so many of them, highlights how much more we have to learn about our oceans and raises so many questions that need answers for effective management and sustainable use of our marine environment,” says Easton.

Octopus moving along underwater mountain off the coast of Chile
An octopus documented during Dive 674. Credit: ROV SuBastian / Schmidt Ocean Institute

Main image: A galaxy siphonophore observed during Dive 672 along a transect on the northern flank of Motu Motiro Hiva, an uninhabited island along the Salas y Gómez Ridge. Motu Motiro Hiva is surrounded by the southwesternmost shallow coral reefs of the Polynesian Triangle. The dive started at ~1200 m depth and traveled upslope to ~190 m. The island is located near the western extent of the Salas y Gómez Ridge off the coast of Chile. Credit: ROV SuBastian / Schmidt Ocean Institute

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