Historic expedition unveils vast coral reefs thriving off Uruguay
A team of scientists from Uruguay has discovered that deep-sea coral reefs off the nation’s coast are thriving. The reefs are made up largely of a species recently listed as vulnerable to extinction and were documented during a Schmidt Ocean Institute expedition that concluded on 19 September.
Formed by Desmophyllum pertusum, a slow-growing cold-water stony coral, the reefs turned out to be healthier, larger and richer with life than expected. One of the largest reef complexes was found at a depth of 300 metres, stretching across 1.3 square kilometres, an area bigger than 180 football pitches. The tallest mound reached 40 metres in height.
“We always expect to find the unexpected, but the diversity and complexity of what we found exceeded all our expectations,” said the expedition’s chief scientist, Dr Alvar Carranza of the Universidad de la República and the Centro Universitario Regional del Este. Carranza and others had first detected the coral reefs in 2010 using mapping technology.
Crystal squids and tripod fish
Using Schmidt Ocean Institute’s remotely operated vehicle (ROV) SuBastian on board research vessel Falkor (too), the team observed a mix of both temperate and subtropical species, supported by warm- and cold-water currents that meet off Uruguay’s coast. Colourful residents found living among the reefs included bellowsfish (also known as hummingbird fish), slit shell snails, groupers and sharks.
The data collected from the expedition will guide how Uruguay’s marine resources are managed, Carranza said. While there is only one confirmed vulnerable marine ecosystem, or VME, in Uruguay at this time, the 29-day expedition provides evidence that more vulnerable areas exist. The team discovered at least 30 suspected new species, including sponges, snails and crustaceans. They documented hundreds of species never before seen in Uruguayan waters, such as crystal squids, the dumbo octopus and tripod fish.
Shipwreck survey
They were also the first to explore the wreck of the ROU Uruguay, a cannon-class destroyer that initially served as the USS Baron during World War II. The United States transferred it to Uruguay in 1952, who used it for several decades as a patrol and training ship until sinking it as a naval exercise in 1995. The science team spent a full day studying the wreck, which now serves as a reef habitat. They also collected data to better understand how the shipwreck has changed over time and assess the presence of any contaminants.
“Discovering marine life reveals the hidden depths of the oceans and transforms the way we perceive our world,” said team member Dr Leticia Burone of the Universidad de la República Uruguay. “RV Falkor (too)’s divestream capabilities allowed us to connect directly with the people of Uruguay and show them our discoveries in real time.”
Chemical energy from the seafloor
In another location they observed worms (Lamellibrachia victori) that live on cold seeps – areas where chemicals such as methane are emitted from the seafloor – growing adjacent to the reef mounds. These two communities survive on different energy sources. Deepwater corals rely on microscopic food from the water column, whereas the worms feed on chemical energy from the seafloor.
“We’ve seen glimpses of this relationship in the Gulf of Mexico, but I have not seen a more perfect visual example of the association,” said Dr Erik Cordes, a deep-sea coral and seep expert who is a professor at Temple University and has led previous expeditions with Schmidt Ocean Institute. It is a natural part of the community’s biological evolution. “The reefs they discovered are incredible,” he added.
The team also observed a sea snail called an ovulid feeding on gorgonian soft coral, which is a common image in tropical areas of the ocean. However, in these cooler waters, it is akin to finding a giraffe in Antarctica, said Carranza.
“This was Schmidt Ocean Institute’s 100th expedition and we are delighted that it took place in the beautiful waters off Uruguay with such an engaging team of scientists,” said Schmidt Ocean Institute’s executive director, Dr Jyotika Virmani. “We were also honoured that Uruguay’s President Yamandú Orsi graciously visited the vessel just before it set sail to wish the scientists and crew a successful voyage as they explored this previously never-before-seen part of the world.”
