Scientists using a robotic explorer have discovered over a thousand organized fish nests beneath Antarctica's Weddell Sea, exposed after a massive iceberg calved in 2017. The nests, built by yellowfin noties, form geometric patterns on the seafloor and highlight a thriving ecosystem in extreme conditions. This finding underscores the need to protect the region as a marine sanctuary.
In the western Weddell Sea, an area once hidden under 200 meters of ice, researchers uncovered vast fields of meticulously arranged fish nests. The discovery became possible following the 2017 calving of iceberg A68 from the Larsen C Ice Shelf. This colossal iceberg, measuring 5,800 square kilometers, exposed previously inaccessible seafloor to scientific exploration.
During the 2019 Weddell Sea Expedition aboard the South African research vessel SA Agulhas II, the team deployed a remotely operated vehicle (ROV) to survey the area. The expedition's goals included studying the Larsen C Ice Shelf's role in stabilizing glaciers and searching for the wreck of Ernest Shackleton's Endurance, lost in 1915. While pack ice thwarted the Endurance search that year, the effort honed skills later used in the successful 2022 Endurance22 mission, which located the ship at 3,008 meters deep.
The ROV revealed more than a thousand circular nests, each cleared of surrounding plankton debris, creating striking geometric patterns. Some nests stood alone, others formed curved lines or clusters. The builders are yellowfin noties (Lindbergichthys nudifrons), an Antarctic rockcod species. Parent fish guard the nests, employing a 'selfish herd' strategy where central positions offer protection, while solitary perimeter nests suit stronger individuals. This mix of cooperation and competition bolsters colony survival.
The site qualifies as a Vulnerable Marine Ecosystem, vital for Antarctic biodiversity. It builds on prior research, like Purser et al. (2022), identifying major fish breeding areas. Protecting the Weddell Sea as a Marine Protected Area could safeguard penguins, seals, and the underlying food web, emphasizing life's resilience in harsh environments.