- The Comau Fjord, in the Chilean region of Patagonia, is one of the only sites in the world where the cold-water coral Desmophyllum dianthus lives just 5 meters (16 feet) below the sea surface.
- The easy access to these animals, which elsewhere live at extreme depths, motivated a group of scientists to study them.
- Their research brought new information to light about the corals’ biology and also revealed that the Comau Fjord is at serious risk.
The Comau, Reñihue and Reloncaví fjords, located in southern Chile’s Los Lagos region, are one-of-a-kind natural laboratories that host diverse species of crustaceans, sea anemones, sea cucumbers, polychaetes and corals. These bodies of water are narrow inlets left by glacial erosion that feed the ecosystem of the Patagonian Sea.
Chilean Patagonia is shaped by its southern, central and northern fjords. Despite being related, “they contain species with very different characteristics,” says Vreni Häussermann, a German-Chilean biologist and marine explorer who has studied the Comau Fjord for more than two decades.
The Reñihue and Comau fjords are the only places in the world where large populations of the cold-water coral Desmophyllum dianthus can be found near the water’s surface. The species congregates mostly in the Comau Fjord, where it works as a bioengineer, constructing three-dimensional structures that shelter other species. This is one of the reasons why the Chilean government declared the Comau Fjord a Protected Coastal Marine Area of Multiple Uses (AMCP-MU) in 2003.
Despite its importance, the Comau Fjord is in a state of “serious deterioration” due to the effects of salmon farming and the advance of climate change, says Häussermann, a professor at San Sebastián University in Chile.
Out of an attempt to halt the degradation of the fjord was born the urgent need to “carry out investigations of the species that live in Comau,” Häussermann says, and that is precisely what she and a group of scientists carried out last year.
New information for science
In 1998, Häussermann and Günter Försterra, chief scientist and research coordinator at the San Ignacio del Huinay Foundation and a professor at the Pontifical Catholic University of Valparaíso, the study’s principal researchers, were the first to discover banks of D. dianthus coral in the Reñihue Fjord in northern Patagonia.
They called the species “fjord coral” and later, in 2003, they discovered more banks of the animals while diving in the shallow waters of the Comau.
This isn’t a common finding. The species lives in other parts of the world, but below 6,000 meters (about 20,000 feet) deep. In Chile, however, the coral is found just 5 m (16 ft) below the surface. “Samples can be found just by diving,” says Ignacia Acevedo-Romo, a marine biologist and research assistant in the study. Given the accessibility of the Comau corals, Häussermann was eager to study the species.
In March 2022, Acevedo-Romo and Ana Navarro Campoy, a marine biologist who collaborated in the investigation, traveled to the AMCP-MU Comau Fjord to dive into the frozen Patagonian waters in search of samples to study how and when the fjord coral reproduces.
Collaborating with the San Ignacio del Huinay Foundation, they chose the optimum location and collected specimens. The corals were later moved to aquariums with a semi-closed system circulating seawater cooled to 10-11° Celsius (50-51.8° Fahrenheit) to recreate conditions as close as possible to those of their natural environment.
It’s impossible to determine the sex of individual D. dianthus corals before they spawn. “Between five and six individuals were distributed randomly into each aquarium” to provide a decent chance of having males and females in the same tank, Acevedo-Romo says.
The team monitored the corals daily and fed them zooplankton and phytoplankton. After approximately six weeks, they began observing signs that the corals would soon spawn. “The corals inflate with water, which indicates that they are close to releasing eggs,” Acevedo-Romo says. Through the spawning behavior, the team was able to identify seven males and five females.
Fjord coral laying eggs. Video courtesy of the Desmophyllum dianthus research team.
Furthermore, they were able to “determine the times that the egg started to divide, when it transformed into a blastula, and at which moment it became a moving larva,” Acevedo-Romo says. In other words, they discovered how and when the species reproduces.
Until the study, this cycle was unknown; there was only one previous record of the seasonality of D. dianthus spawning, which was carried out by Rhian Waller, a professor of marine sciences at the University of Maine in the U.S.
Waller’s research established that the species spawns in shallow waters, and that it does so in August, the middle of winter in the Southern Hemisphere, when the waters are at their coldest. However, the research didn’t manage to establish other fundamental steps in the reproduction process, like fertilization and larval development. So the data produced in this recent investigation, in which Waller was invited to collaborate, were a great success for the research team and for science as a whole.
The bioengineering corals of Comau
The coral banks formed by Desmophyllum dianthus are also called marine animal forests, because “it’s like a forest on the land,” Häussermann says.
These marine animal forests slow ocean currents. According to Försterra, the currents speed up in proportion to the smoothness of the ocean floor: the corals form a three-dimensional structure that acts as a barrier to the currents, and also shelters crabs and other small crustaceans.
These habitat-forming properties are why the fjord coral was chosen as a conservation target in the AMCP-MU Comau Fjord’s management plan, which Chile’s Ministry of the Environment had yet to approve when this article was originally published by Mongabay Latam in September 2022.
Threats facing the corals of Comau
The species classification by the Ministry of the Environment places the fjord coral in the “near threatened” category, meaning that it urgently needs protecting. This is principally due to climate change and human impact.
Today, after more than 1,000 dives and more than 1,900 species recorded, Häussermann is coming to terms with the worrying deterioration of the AMCP-MU Comau Fjord. In 2012, she and other researchers noticed a huge die-off of corals in the area. It happened fast. “One week they were fine, and the next they were all dead,” she recalls.
According to an investigation by Mongabay that mapped the salmon-farming concessions within Chile’s protected areas, there are five such concessions in the Comau Fjord, which Häussermann says existed before the protected area was established.
Studies show that one of the biggest problems caused by salmon farms occurs when the water runs out of oxygen and causes sea life to die, a phenomenon known as hypoxia.
This happens when salmon feces and leftover feed accumulate under the cages holding the fish. Both the feces and the feed contain nutrients, and large concentrations of them spur microalgal blooms. These algae live for barely a week; when they die, they fall to the seafloor. Bacteria consume them, using up the oxygen in the water and causing hypoxia.
On top of this threat, in the year of the mass coral die-off there was also increased volcanic activity, which raised methane and sulfur levels in the water. By then, research had found that some invertebrates suffer more from hypoxia when under the influence of these two compounds, says Häussermann, and this was exactly what occurred in the Comau Fjord.
According to the results of the study, what killed the corals in the Comau Fjord was “an excess of methane and sulfur produced by natural volcanic activity, combined with hypoxia, which most probably came from salmon farming activity,” Häussermann says.
In January 2020, the Interdisciplinary Center for Aquaculture Research (INCAR) presented a proposal with contributions from more than 30 scientists that strongly called upon aquaculture-industry regulators to improve how the environmental impact of this constantly growing sector is monitored and approved.
Doris Soto, an ecologist and principal researcher at INCAR, says that because salmon farming occurs in all fjords in Los Lagos, including the Comau Fjord, “it is not possible to compare potential impacts in relation to an unaffected ecosystem.”
“The [INCAR] proposal suggests establishing fjords with no salmon farming that can serve as a reference point and a control to evaluate impacts on an ecosystem level,” Soto says. One of these fjords would be the Comau, which would mean withdrawing existing concessions and waiting for the ecosystem to completely recover.
Felipe Paredes, coordinator of protected areas for the Ministry of the Environment, told Mongabay that once the ministry approves the management plan of the AMCP-MU Comau Fjord, it will define priorities for its implementation.
“Salmon farming has been identified as an activity affecting the conservation targets of the protected area,” Paredes says, adding “the farms must somehow be moved as far from the fjord as possible.”
From a legal perspective, however, the decision about whether to withdraw the concessions in the fjord falls to Chile’s Undersecretariat for Fisheries and Aquaculture.
The study of coral reproduction was carried out through the National Fund of Scientific and Technological Development (Fondecyt), awarded to the Pontifical Catholic University of Valparaíso (PUCV), and developed under the direction of the scientist Günter Försterra.
Banner image by @Vreni Häussermann & Günter Försterra.
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