Scientists Document First-Ever Biofluorescent Fish in the Arctic

A juvenile Liparis gibbus imaged under white light (top) and under fluorescent lighting (bottom) conditions.
A juvenile Liparis gibbus imaged under white light (top) and under fluorescent lighting (bottom) conditions.
Image: J. Sparks, D. Gruber, P. Kragh

There’s so much about our planet that scientists are still learning about. Case in point: American Museum of Natural History researchers recently documented biofluorescent fish in the Arctic for the first time ever. Their find was published on the museum’s online research library on Thursday. The report shows how little we still don’t know about the Arctic—and how much we stand to lose as the climate crisis worsens.

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Bioflourescent organisms absorb beams of light from their surroundings and then emit them from their bodies, causing them to glow in the dark. It’s a similar phenomenon to bioluminescence, but the key difference is the creatures can’t produce a glow absent of surrounding light sources.

The story of the discovery starts in 2014, when two scientists researching bioflourescence came up with a theory. On research expeditions together, the two had identified the trait in more than 180 tropical fish species, but knew it was thought to be uncommon in the Arctic because the region gets very little to no sunlight in the winter. In the summer, however, the sun shines around the clock. They posited that there may be organisms soaking up the summer sun and emitting it back out.

Exploring Greenland’s Icy Waters, a video on the expedition by the American Museum of Natural History (via American Museum of Natural History on Youtube)

The scientists got a shot to test their theory in 2019 when they joined up with an expedition that cruised the eastern Greenland coast, allowing the scientists the chance to dive near icebergs and among the region’s kelp forests. As they spent hours in the frigid waters, they came across many of the same species that are found in warmer tropical and temperate waters, including scorpionfishes and flatfishes. But while these creatures are bioflourescent in lower latitudes, they seemed incapable of using those powers in the Arctic. When the researchers exposed them to light, they didn’t glow at all, leaving the AMNH scientists dejected.

“In the tropics, almost all hard corals are fluorescent, many of the anemones are flourescent, but when we get to Greenland it’s almost zero,” David Gruber, a research associate at the American Museum of Natural History who also teaches biology at Baruch College and was a co-author of the study, said in a video about the trip.

But the duo kept looking, and eventually, they found what they were looking for. They came upon not one but two young variegated snailfish (technically called Liparis gibbus). The scientists saw both of the fish emit green and red light from their bodies, marking the first time the trait has even been observed in the Arctic. It was also a rare example of a single organism emitting multiple colors.

Aerial view of iceberg-filled habitat in Sermilik Fiord, eastern Greenland, near where specimens of Liparis gibbus were collected. The authors can be seen underwater in center of image
Aerial view of iceberg-filled habitat in Sermilik Fiord, eastern Greenland, near where specimens of Liparis gibbus were collected. The authors can be seen underwater in center of image
Photo: P. Kragh/© AMNH

The research also documents another case of biofluorescence using lab equipment. The team from AMNH worked with scientists at the National Oceanic and Atmospheric Association to test a fully-grown kelp snailfish (or Liparis tunicatus), which was found on the Pacific side of the Arctic in the Bering Strait. When they exposed the fish to dim blue LED light, it lit up red, an indication that it potentially—thought not definitely—exhibited the trait in the wild.

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The authors’ findings show that bioflourescence isn’t just theoretically possible in the Arctic. It’s actually happening, and fish found thousands of miles apart exhibit the trait. But what and how exactly the creatures are using the trait is still unknown. Scientists suspect animals may use it for communication or mating, but without further examination, we won’t know much about its use to snailfishes.

The authors collecting specimens on iceberg shown in the image above.
The authors collecting specimens on iceberg shown in the image above.
Photo: P. Kragh/© AMNH
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Yet the window opened into these creatures’ mysterious lives may already be closing. The Arctic is warming at three times the rate as the rest of the world, unleashing a host of ecosystem shifts that could imperil native species. Research has shown that the region is undergoing “Atlantification” as the seas that ring the high Arctic warm. Sea ice is plummeting to record lows as well. In the Bering Sea, paleoclimate research shows sea ice hasn’t been this low in at least 5,500 years. All of these shifts could be inviting for creatures from other marine ecosystems to swim in, displacing those that are already there.

“Greenland is really discussed a lot in the news, it being ground zero for climate change,” Gruber said. “As the waters begin to warm, are there going to be new fish coming in that didn’t used to be there?”

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Without major changes, these changes will only occur more rapidly. The biggest factor in determining the Arctic’s future is how quickly the world reduces greenhouse gas emissions. While there are numerous reasons to do that, the new research is a reminder of how much we still have to learn about the region.

Staff writer, Earther

DISCUSSION

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Dense non aqueous phase liquid

But what and how exactly the creatures are using the trait is still unknown. Scientists suspect animals may use it for communication or mating, but without further examination,

Why not both? Biofluorescence may communicate a desire to mate - may the best lightshow win. Or not. Or. In the deep cold dark sea, fish biofluorescence may be used similarly to how the game Marco Polo is played. That’s probably low on the plausibility scale. Is anybody here an ichthyologist?