SCIENCE
There are reefs on the continental slope that managed to adapt to cold, deep waters; What is your hidden wealth?
Corals in Uruguay? But what if here we don’t have those transparent and warm waters of the Caribbean? Is this checked? These and other questions are being answered Alvar Carranza since 2010 when he identified for the first time for Uruguay a series of reefs in the area of the continental slope (100 miles from the coast; approximately 185 kilometers). And the questions echoed again recently when it became known that the international expeditions of Pristine Seas National Geographic Society and of Mission Blue They photographed the great biodiversity of the Uruguayan sea, which includes those colorful structures that are thought to only exist in tropical waters. Know it now: Uruguay has reefs that have developed the ability to inhabit cold, deep waters.
However, also know that this does not mean that Uruguayan corals do not continue to be a mystery. “We have not yet been able to study the hundreds of samples of associated species,” said Carranza, professor and researcher at CURE (Maldonado headquarters).
In these 12 years he presented several projects that did not obtain financing; Now he is waiting for international funds that will allow him to return to the area with a remotely operated submersible drone to find out the state of health of these threatened ecosystems.
“Many of the species kept in the National Museum of Natural History They are not described for Uruguay or for science,” he noted.
The Miguel Oliver expedition.
The discovery of corals in 2010 “was not surprising,” in the researcher’s opinion, but you have to go back to 1876 to obtain information. That year, the HMS Challenger –the first ship that made an almost global deep-water expedition– described a species of coral from cold and deep waters for our country but with very specific specimens.
Almost 100 years later, the German Walther Herwig recovered other isolated samples of reef-building corals. Both cases occurred at the edge of the continental shelf. At the beginning of this century there were also specific records that came from scientific observers on board fishing vessels.
It was the trip aboard the Spanish ship “Miguel Oliver” (whose mission was to map a large part of the Uruguayan continental margin and had the participation of scientists from the Spanish Institute of Oceanography, the General Secretariat of the Sea of Spain and the National Directorate of Aquatic Resources) which changed what was known to date: acoustic mapping of the continental slope made it possible to detect 17 mounds in which evidence of live coral or coral rubble was found. In other words: reefs.
Some data: these were found at depths ranging from 167 meters to 326 meters and the average height of the mounds was 35 meters (the largest was 67 meters). The predominant species was Desmophyllum pertusum, this finding being the first report of deep-water coral reefs on the Uruguayan continental shelf and slope and the southernmost record in the South Atlantic Ocean. In appearance, “they are very similar to tropical corals,” Carranza illustrated. The main difference is that these inhabit warm waters and at very shallow depths and maintain a symbiotic relationship with organisms that need sunlight to survive. “Cold water corals do not require this symbiosis and can live in deep waters,” he explained.
Added to this were a few “dozens” of georeferenced records (but without obtaining samples) in 2020, which leads Carranza to conclude that the Uruguayan continental slope “is an environment conducive to the development of coral reefs”. That is, the underwater landscape would surprise us with those large three-dimensional structures full of color and life.
The importance of reefs.
The total surface area of coral reefs in the world occupies less than 0.1% of the ocean area and, thus, tiny, provides home for at least 25% of all marine species. The continental slope is part of that wealth that still remains almost secret and that requires urgent attention. “They are thousands of years old. They are structures that grow very slowly. We don’t know what their state of health is,” said Carranza, referring to the already known Uruguayan corals and those not yet explored.
The threats are known: fisheries that destroy corals with their nets, oil exploration, underwater cables and underwater mining, and possibly ocean acidification. For this reason, the researcher agreed with the recommendation made by experts from the Pristine Seas National Geographic Society to the government to declare a marine protected area.
Furthermore, there is much more to investigate: not only hundreds of samples preserved since 2010 that “are very poorly inventoried” but also the presence of reefs formed by other species must be confirmed (e.g. Bathelia candida) and advance our knowledge of other types of corals.
Protection for species and even drugs.
Corals are not plants; They are small animals, called polyps. There are solitary corals, colonial corals, reef builders, soft corals, false corals… and not all corals live near the surface in warm tropical waters. “Coral reefs, whether in shallow tropical waters or cold, deep waters, provide habitat for many animals. The complex 3D structure provides holes, pockets, nooks and crannies that serve for animals to take refuge from predation, as well as to reproduce and feed,” Whitney Goodell, a marine ecologist who participated in the Pristine Seas National expedition, told El País. Geographic Society on the Uruguayan continental slope (approximately 185 kilometers from the coast).
The mission did not directly photograph the corals (since they were several meters below what their depth cameras or high-definition drop cams were able to capture) but it did photograph several species that are known to use the reefs as their home. “They are areas rich in nutrients and with an abundance of life and biodiversity. “They are critical habitats for the sustenance of these organisms,” she noted. The animals observed by the drop cams included grenadiers, red crab, rays, squid, deep sea brotola, rouget and a tuna, probably southern bluefin tuna, a critically endangered species. In cold, deep waters, reefs may be the only structure that provides protection.
Another reason to preserve coral reefs is that they are reservoirs of substances of pharmaceutical interest. For example, antitumor, antimalarial, antimicrobial and antituberculosis compounds, among others, have been identified from some species.
Mission Blue: not only in deep water.
Mission Blue, promoted by the Environment and Climate Change Division of the Rocha government, with inter-ministerial support in conjunction with international researchers, covered some 1,230 kilometers of “Rocha jurisdictional waters” between low reefs (areas less than 20 meters deep) between 30 and 40 nautical miles from the coastal zone (between 60 and 80 kilometers). Solitary corals were recorded here, as well as anemones, fish and many more species. Rodrigo García Pingaro, director of Environment and Climate Change at Rocha, told El País: “We managed to see an iota of the unique beauty of the ocean floors that we do not know about in our country.” Regarding the corals (not reef-forming ones like those found on the continental slope), he expressed: “They are oceanic gardens that we still have time to conserve.” And in reference to the oceans he pointed out: “They capture more carbon dioxide than forests; It is estimated that 20 times more. Hence the importance of conserving these areas, which also include critically endangered species such as angelfish, dogfish and catfish.”
