The researchers write in the journal current biology On January 13, a huge breeding colony of ice-crushed ice fish was discovered in the southern Weddell Sea in Antarctica. They estimate that the colony covers at least 240 square kilometers and has about 60 million active nests. The unprecedented colony represents a fish biomass of over 60,000 tons (or more than 135 million pounds).
“Our most important finding is the pure existence of such a vast ice fish farming colony,” says Autun Purser of the Alfred Wegener Institute in Bremerhaven, Germany. “A few dozen nests have been spotted elsewhere in Antarctica, but this find is an order of magnitude larger.”
Purser and colleagues made the discovery while surveying the Filchner ice shelf using the Ocean Floor Observation and Bathymetry System (OFOBS). “This is basically a large, one-ton hauling device that we pulled behind the RV Polarstern icebreaker at a speed of one to four kilometers per hour,” he explains. “We’re pulling this about 1.5 to 2.5 meters above the sea floor, and we’re recording video and acoustic bathymetry data.”
The researchers were particularly interested in this region of the sea floor because they knew it contained upwelling water about two degrees Celsius warmer than the surrounding seafloor. However, the rest of what they found was somewhat unexpected.
“We weren’t taught to expect what kind of fish nest ecosystem,” says Purser. This part, he adds, was a “complete surprise”.
The majority of the nests they discovered were occupied by a single fish guarding more than 1,700 eggs. They also observed many dead fish carcasses in and around the nesting colony, indicating that fish play an important role in the larger food web. While more study is needed, they suspect the colony is heavily used by predators such as Weddell seals.
“Very many Weddell seals spend most of their time in close proximity to fish nests,” says Purser. “We know this from historical tracking data and recent tracking data from our cruise. Nests are exactly where the warmest water flows. These facts may be coincidental, and more work is needed, but recorded seals data shows that seals are indeed diving deep Fish nests, it’s okay to eat these fish.”
The results revealed a globally unique ecosystem, according to the researchers. It also provides support for the establishment of a regional marine protected area in the Southern Ocean under the Convention on the Conservation of Antarctic Marine Living Resources.
The researchers have now deployed two camera systems to monitor the ice fish’s nests until the research vessel returns. We hope that images taken several times a day will yield new insights into the workings of this newly discovered ecosystem. Purser says he has plans to return in April 2022 to conduct seafloor surveys in areas of the northeastern Weddell Sea.
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Autun Purser, a vast ice fish farming colony discovered in Antarctica, current biology (2022). DOI: 10.1016/j.cub.2021.12.022. www.cell.com/current-biology/f… 0960-9822 (21) 01698-5
the quote: An ice fish spawning colony with 60 million active nests found in Weddell Sea, Antarctica (2022, Jan. 13) retrieved Jan. 13, 2022 from https://phys.org/news/2022-01-icefish-colony-million- weddell-sea. programming language
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