Discover the largest nesting colony in the Antarctic

According to a new study, 500 meters below the ice that covers the Antarctic Sea is the largest known colony of reproductive fish. It is estimated that 60 million active nests of a type of iceberg are spread over at least 240 square kilometers.

Many fish nest; But researchers have so far only encountered a few or perhaps a few icebergs at a time. According to past knowledge, even the most grouped species of nesting fish gather in the form of only a few hundred fish.

Researchers reported in the January issue of the journal Current Biology that icebergs are likely to have a profound and unknown effect on Antarctic food chains. Otten Presser, a marine biologist at the Alfred Wegner Institute in Germany, and colleagues encountered the massive colony in early 2021 during a research voyage in the Weddell Sea, located between the Antarctic Peninsula and the mainland.

Researchers were studying the chemical connections between surface water and seabed. Part of the research involved examining the life of the seabed by towing a device behind the scientists’ research ship. Moving smoothly over the ocean floor, the device used video and audio to plot sea floor features.

One of Presser’s co-workers was towing the camera to a spot on the Filsner ice rink in the Weddell Sea, and found that the camera was constantly lined with Jonah icy ice nests at the bottom.Neopagetopsis ionah) Collides.

Ice fish Jonah / Neopagetopsis ionah

Neopagetopsis ionah forms circular nests with hard rock centers and can lay more than a thousand eggs in them.

Crocodiles from the crocodile’s family (Channichthyidae) Are found only in the Antarctic Ocean and Antarctic waters and have strange adaptations to extreme cold. They have clear blood that is rich in antifreeze compounds. “When I went down half an hour later and saw all the nests behind me for four hours, I thought I had encountered something unusual,” explains Presser.

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Presser and colleagues conducted three more surveys in the area and also observed nests with similar densities. He says that perhaps one of the closest ice-like specimens among the fish that lay in the nest is the gills.Lepomis macrochirus) That form reproductive colonies that can contain hundreds of fish. However, according to measurements showing that there is about one iceberg per four square meters in hundreds of kilometers of territory, the Weddell Sea colony is several times larger.

“This colony is an amazing discovery,” says Thomas Dwings, an evolutionary biologist at the University of Oregon. He is particularly affected by the very high density of nests. “It reminded me of bird nests,” says Dings. “Crocodiles and other seabirds nest together in the same way.”

It is not clear why so many icebergs gather at one point for reproduction. There seems to be good access to plankton here, which can be an important food source for hatching fish. Researchers in the area also found areas with slightly warmer water that could help icebergs find their breeding grounds.

Icefish nests in the Antarctic / icefish

Recent video and audio studies have shown that a type of Antarctic fish called the Jonah iceberg comes together in multimillion-dollar clusters to form a circle of circular nests that stretch for miles.

Researchers say that icebergs can feed the seagulls of the Weddell Sea. Past studies have shown that jaws spend a lot of time diving in this area.

Presser thinks there may be smaller colonies of icebergs near the coast, where there is less ice cover. It is also possible that the ova rely disproportionately on large-scale reproductive colonies and place virtually all of their eggs in one basket.

In that case, Dwings says, the species would be highly vulnerable to extinction. He says the discovery of a huge colony is another reason to offer environmental protection to protect the Weddell Sea ecosystem.

Currently, two seabed cameras are deployed at the colony site. The cameras will remain in the area for the next few years, taking pictures four times a day to determine if the nests will be reused over time. “I can say that this huge colony is almost a new ecosystem on the seabed,” says Purser. “It’s amazing that it has never been seen before.”

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