Marine Science
Extensive deep warm-water coral frameworks pinpointed in the Red Sea
A habitat suitability study suggests that two stony coral species may form significant deep-sea frameworks across the northern Red Sea and Gulf of Aqaba.

The Red Sea is significantly warmer and more saline, even in its deepest waters, than other marine basins. These conditions offer opportunities for unique ecosystems to develop, such as deep warm-water coral frameworks. However, little is known about these deep coral ecosystems and their distribution in the Red Sea.
KAUST researchers, together with scientists in the U.S. and Italy, used a computer modeling approach combined with data gathered on ocean voyages to determine the likely distribution of deep warm-water coral frameworks in the northern Red Sea and the Gulf of Aqaba.
“This region has steep underwater slopes very close to shore, meaning that deep-sea ecosystems could be directly impacted by human coastal activities,” says Ph.D. candidate Megan Nolan, supervised by KAUST faculty Francesca Benzoni, who worked on the project with a team. “The NEOM development on Saudi’s northern coast is keen to safeguard marine ecosystems and invest in sustainable tourism there.”
Both shallow and deep coral frameworks are built by stony corals and offer a range of ecosystem services, including providing habitat for fish and other creatures. These frameworks form the base of coral reefs and are crucial to promoting marine biodiversity, yet even deep-sea reefs are now under threat from ocean acidification, global warming and other damage caused by human activity.
Coral frameworks are extensive enough to modulate the shape of the seafloor. The living framework is accompanied by the rubble of dead coral, which offers a vital substrate for different corals and other species to grow. However, not all deep-sea coral species form frameworks.
“Even the Caryophylliidae and Dendrophylliidae coral families that we observed in this study do not always form frameworks. The exact conditions and processes needed to trigger these formations are puzzling,” says Nolan.
Studying these enigmatic structures is hampered by accessibility issues and high costs. While Remotely Operated Vehicles (ROVs) and submersibles offer considerable insights, they can only survey narrow transects of the seafloor each time. Nolan and co-workers developed a habitat suitability model using ROV and sensor data gathered from the NEOM-funded “Deep Blue” expedition on the M/V OceanXplorer in 2020. They knew the location of several deep-sea frameworks built by different corals and used this information to predict further likely locations for each species.
“Habitat suitability models collate data on specific environmental conditions in places where frameworks are known to survive and then assess the whole study region to identify areas with similar conditions,” says Nolan.
The model assessed 12 variables including water temperature, salinity and sea-floor topography. The team found that a total area over 250km2 was suitable for deep-coral frameworks in the study zone.
Frameworks built by the Caryophylliidae corals probably cover more than 100km2 of sea floor, exclusively in the northern Red Sea. Dendrophylliidae coral frameworks could cover a wider range, at least 150km2 of seafloor across both the northern Red Sea and the Gulf of Aqaba.
On a second OceanXplorer voyage, the researchers visited some of the locations suggested by their model and found coral frameworks present either exactly where predicted or close by.
“Frameworks of this size could act as significant carbon factories, potentially influencing carbon and nutrient cycling in the Red Sea,” concludes Benzoni. “This work is part of a wider effort to characterize deep-sea species, and KAUST’s teams will continue to investigate this understudied environment.”
You might also like

Marine Science
Examining phytoplankton’s past to reduce future algal blooms

Marine Science
Cheap fixes aid global coral reef conservation

Marine Science
Giving coral reefs a fighting chance for survival

Marine Science
Extinction risk of high value sharks

Bioscience
Tracking coral probiotics unlocks symbiotic secrets

Marine Science
Rolling "balls" provide substrate for marine life

Bioscience
Cataloging the complexity of the ocean genome

Bioscience