A Giant Icefish Breeding Colony Discovered Beneath Antarctic Seas

When the bottom of the Weddel sea was captured by the camera which was remotely operated, Lilian Boehringer could see the icefish nest. Lilian is a student researcher at Alfred Wegener Institute in Germany. These icefish nests were spotted over a thousand feet below the icy surface. The seafloor was covered with sandy craters where each held a single, stolid starfish. These creatures with massive hearts and transparent blood can survive in waters that are just above freezing. Their blood lacks red blood cells and hemoglobin, giving it a transparent appearance. This loss of hemoglobin may be an evolutionary adaptation, as it allows absorption of Antarctic waters through their skin.

Giant Icefish Breeding Colony
Source: PS118, AWI OFOBS team

This rare sighting of icefish nests happened in February 2021. The research ship named Polarstern arrived at the Weddel sea to study some other things. Around 3 am, the camera kept revealing images of icefish nests every 20 seconds, as it moved with the ship. This never-ending collection of icefish nests truly astonished Ms. Boshringer. She was joined by a deep-sea biologist named Autun Purser about 30 minutes later. When they checked the camera feed, it was completely full of icefish nests.

This Icefish Spans Over A Whopping 92 Square Miles

For the nest four hours too, the camera captured nothing but icefish nests, which added up to 16,160. As estimated by scientists, this colony of Neopagetopsis ionah icefish spans over 92 square miles in the Antarctic sea. They also assume that there are over 60 million active nests. In the journal ¬†Current Biology, scientists named this location as the ‘Largest fish breeding colony ever discovered’. Biologist Mario La Mesa states that this discovery provides proof of a benthic ecosystem in the Weddel Sea which has not been described so far. He also states that it won’t be surprising to find enormous colonies at other locations too.

Giant Icefish Breeding Colony
Source: PS118, AWI OFOBS team

In every nest, around 1,735 large, yolky eggs were present on average. An unprotected clutch can become easy prey for creatures like starfish, sea spiders, etc. Therefore, the male fish guards the young to ensure their safety. They use their elongated lower jaw the clean their nest, as claimed by Manuel Novillo, a researcher at the Bernardino Rivadavia Museum of Natural Science in Argentina. A single fish guarded around 3/4th of the nests. The other nests contained eggs, but no fish. Closer to the edges of the colony, there were numerous abandoned colonies as well. In these, we can see starfish or octopuses preying on icefish carcasses.

Giant Icefish Breeding Colony
A Weddell seal, which feasts on the icefish nests. Source: Mia Wege/University of Pretoria

An Abandoned Littered Seaflloor Was Found 31 Miles West

According to researchers, this colony occupies an unusually warm area in the deep waters. Its temperature measures around 35 degrees Fahrenheit, which is really hot when compared to other Antarctic waters. The discovery of this massive icefish nest leaves scientists with more questions than answers. Either way, researchers assume that there can be a special reason regarding the location of this colony. They found another patch of littered seafloor around 31 miles west. These abandoned nests were overtaken by sponges and corals.

Before returning to the land, the researchers even deployed a camera to further monitor the lifecycle of icefish. This will daily photograph the site every day for two years. So, share your thoughts about this rare and interesting observation in the comments.

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