At the western end of the Weddell Sea, an international team came across a large colony of nests de peces Where a frozen desert was expected: beneath an ice shelf some 200 meters thick. The discovery, made with a remotely operated robot, has revealed an orderly and living ecosystem in an environment that seemed inaccessible.
The opportunity to explore that area came after the landslide of iceberg A68 In 2017, it uncovered previously unseen deposits. In 2019, the scientific mission documented more than a thousand circular nests arranged with surprising regularity, reigniting the debate about the protection of this key Antarctic enclave.
How the discovery occurred
The Weddell Sea Expedition 2019 set sail aboard the polar vessel SA Agulhas II to study the waters near Larsen C and, incidentally, search for the wreck of the Endurance. Equipped with autonomous vehicles (AUV) and an ROV nicknamed “Lassie”, the researchers went under the ice pack and sent cameras under the ice, where the ROV transmitted continuous images of the seabed.
The detachment of the A68 acted as a unique “scientific window”opening routes previously closed by permanent ice. The journey was not without difficulties—pack ice forced complex maneuvers—but it allowed for mapping sections of the seabed that had never before been filmed with this level of detail.
In that context, the priority of locating the Endurance It yielded to the unexpected: the ROV detected dozens and then hundreds of circular depressions in the sand, perfectly delimited and clean of debris. The scale of the phenomenon led the team to change their focus to documenting each pattern and its distribution.
The subsequent Endurance22 expedition culminated the historic chapter by finding the ship in 2022, at a depth of 3.008 meters, but the great biological legacy of 2019 was to reveal a massive nursery de peces organized as if it were an underwater neighborhood.
What the images revealed: the 'city' of nests
The recordings show nests about 75 centimeters in size in diameter, excavated and free of the phytoplankton blanket that covers the surrounding area. Inside, an adult fish guards a translucent egg masswhich confirms a active parental care in extreme conditions of cold and darkness.
The authors of these structures are the yellowfin news, cold water fish (Lindbergichthys nudifrons). The colony does not appear randomly: there are lines, curves, dense clusters and solitary nests on the perimeter, as if the sandy bottom had been divided into neighborhoods and avenues.
This design responds to a balance of cooperation and defense which is reminiscent of the “selfish herd” theory and studies on the group behavior Among the fish: those occupying central positions benefit from collective protection, while those at the edges require more vigilance. Larger nests appear at the periphery, likely supported by fish. capable of defending themselves alone.
The whole thing functions like a huge natural nurserycrucial for the reproductive success of the species and for the local food chain. The constellation of nests also suggests a sustained energy investment in keeping the substrates clean and optimizing egg aeration.
Scientific and conservation implications for Europe
The study, published in Frontiers in Marine ScienceIt featured experts from European centers such as the Exeter University, the Nekton Foundation and the Southampton National Centre for Oceanography...in addition to collaborators from leading polar institutes. The consensus is clear: this is a vulnerable marine ecosystem which requires protective measures.
From a European perspective, the discovery reinforces the proposals within CCAMLR to designate new Marine Protected Areas in Antarctica. Safeguarding the Weddell Sea would help preserve essential habitats for fish, penguins and seals, already sustaining ecological processes that impact the balance of the Southern Ocean.
For Spain and the EU, with an active polar scientific community and conservation commitments under the Antarctic Treaty, this evidence adds technical arguments for support protection of the area. International coordination will be key to limiting impacts and ensuring long-term scientific monitoring.
Beyond the visual wonder, the value of the discovery lies in the fact that it provides reproductive behavior data These records are difficult to capture in ice-sealed environments. This type of data feeds into ecological models and guides evidence-based management decisions.
Next steps: technology and monitoring
The teams anticipate new campaigns to map the extent of the colony, measure its persistence over time, and assess how it responds to rapid environmental changes. Monitoring ice conditions, currents, and food supply will help to understand the factors that determine location and nest density.
The combined use of AUV and ROV y acoustic tools This will again be crucial. These platforms allow operation under ice, high-definition video recording, and sampling of physical and biological variables without significantly disturbing the colony—an essential requirement in a such a fragile environment.
Everything suggests that the "city" of nests under the ice is much more than a curiosity: it is a key piece of the puzzle Antarctica that forces us to accelerate the protection of the Weddell Sea and maintain constant scientific monitoring so as not to lose what we have only just learned to see.
