Greenland • Glaciers • Ocean Life • New Research
Scientists sent an underwater robot into one of the most dangerous and poorly observed environments on Earth: the submerged edge of a glacier in South Greenland. Instead of finding a biological wasteland of cold, dark and sediment-choked water, the cameras encountered large aggregations of krill, fish, worms, shrimp, squid, jellyfish and other marine organisms living directly beside the ice.
Glacier fronts are not friendly places for scientific instruments — or scientists.
At a marine-terminating glacier, enormous walls of ice meet seawater while meltwater surges from beneath the ice, sediment pours into the fjord and icebergs can calve without warning.
That danger means scientists know surprisingly little about what is happening right against the submerged face of many glaciers.
So researchers studying Naajat Sermiat, a marine-terminating glacier in South Greenland, did something different.
They sent in a robot.
And what its cameras recorded has revealed a surprisingly busy ecosystem at one of Greenland’s most extreme boundaries between ice and ocean.
A Robot Went Where Research Boats Cannot
The research team used a remotely operated underwater vehicle (ROV) to investigate the glacier-ocean boundary at Naajat Sermiat during field campaigns in May and August 2025.
The glacier rises roughly 30 meters above the water, while measurements at its submerged front reached depths of up to 166 meters.
The ROV carried cameras and, during the August deployment, a temperature sensor, allowing the researchers to observe the glacier face and surrounding water directly.
They combined those observations with measurements from an uncrewed aerial vehicle operating within tens of meters of the terminus and boat-based measurements farther down the fjord.
The combination allowed the scientists to follow the system from the ice itself into the surrounding fjord: meltwater, sediment, temperature, salinity — and marine life.
It is precisely the sort of environment that has been difficult to observe directly because approaching a calving glacier face by boat can be extremely dangerous.
Then the Cameras Started Seeing Life — Lots of It
What appeared beside the ice surprised the researchers.
The ROV documented a remarkably diverse collection of organisms directly at the glacier-ocean boundary, including:
- large aggregations of krill
- capelin
- cod
- copepods
- amphipods
- Mysis
- shrimp
- squid
- jellyfish
- crab larvae
- chaetognaths
- other worms and zooplankton
Krill were the organisms encountered most frequently.
Some were seen swimming immediately beside the ice. Others moved through the highly turbid water created by material emerging from the glacier.
Most intriguingly, the researchers observed krill swimming directly toward actively discharging subglacial plumes.
According to the study, krill have previously been observed feeding in a glacial meltwater plume in Antarctica, but the authors say they are unaware of previous observations showing krill this close to a glacier — directly at the glacier-ocean boundary itself.
Why Were Krill Gathering Against a Glacier?
This is where the discovery becomes particularly interesting.
Greenland’s marine-terminating glaciers are already known to influence biological productivity in fjords.
Fresh meltwater discharged from beneath a glacier is buoyant. As it rises through seawater, it can entrain deeper water and transport nutrients upward toward sunlit surface layers.
That mechanism can stimulate phytoplankton production, which in turn supports zooplankton and larger animals.
Previous research has therefore tended to explain enhanced biological activity around marine-terminating glaciers largely through this nutrient-upwelling mechanism.
But that explanation doesn’t neatly account for what the robot saw.
The observations were made below the photic zone, where there is too little light for meaningful local phytoplankton growth. The water close to the glacier was also extremely turbid — another condition that limits photosynthesis.
Yet krill were gathering there anyway.
That led the researchers to consider another possibility:
the animals may be responding to food and biological material coming directly from the glacier itself.
Can a Glacier Actually Help Feed Marine Life?
A glacier may look like an enormous sterile block of ice, but biologically it is much more complicated.
Greenland’s ice hosts microbial communities, including algae and cyanobacteria. Microbial life has also been found in drainage systems beneath glaciers.
During the melt season, flowing water can mobilize microbes, organic material and mineral particles from the glacier surface and transport them through streams, fractures and moulins into the subglacial drainage network.
Eventually, some of that material can emerge from beneath the glacier directly into the ocean.
The researchers suggest that this biologically enriched material could become a detrital food source for organisms living near the glacier front.
And the robot provided an intriguing clue.
Krill were not merely drifting randomly around the terminus. Some were observed swimming toward active plumes of material being released from beneath the glacier.
That does not mean the researchers have proven exactly what every krill was eating. The study explicitly presents several possible mechanisms.
But the observations challenge the simple picture of the glacier as merely a physical pump that indirectly fertilizes the ocean.
The ice itself may participate more directly in the food web.
The Robot Also Found Dead Fish on the Ice
Not everything at this biological hotspot was thriving.
The researchers observed dead zooplankton and dead capelin resting on the submerged glacier.
One possible explanation for some zooplankton is that freshwater emerging from beneath the glacier could stun organisms transported into the boundary zone, potentially making them easier prey.
The capelin present a different puzzle.
Capelin tolerate substantial changes in salinity and routinely enter environments where salinity varies, so the researchers consider sudden freshwater exposure an incomplete explanation for the deaths.
Instead, they propose that rapid decompression may be involved.
A powerful rising meltwater plume could potentially transport fish upward quickly enough for gases inside their swim bladders to expand.
The authors present this as a plausible mechanism rather than a confirmed cause, but it reveals just how physically extreme the glacier-ocean boundary can be.
It is simultaneously a feeding ground, a transport system and a hazardous environment.
There Were Even “Sediment Waterfalls” Beneath the Ice
The ROV footage revealed another striking phenomenon.
Glaciers transport enormous quantities of rock and mineral material from the continents toward the ocean, making them an important part of ocean geology and seafloor sedimentation.
As ice moves across bedrock, it crushes and incorporates sediment. Other debris becomes embedded higher in the ice after falling from exposed rock and surrounding terrain.
When that sediment-rich ice reaches the ocean terminus, the material can be released underwater.
The researchers observed sediment cascading down features on the submerged glacier face — effectively underwater sediment waterfalls — along with clouds of suspended particles pouring into the surrounding water.
Red polychaete worms were even observed among sediment resting on the glacier ice, suggesting that some organisms may inhabit these unusual sediment-covered microenvironments directly on the submerged glacier surface.
The ice itself was far from smooth.
The ROV recorded vertical channels, ridges and scallop-like structures sculpted into the underwater glacier face by melting and turbulent water movement.
Those structures matter because an irregular ice surface has more area in contact with seawater than a flat wall, potentially affecting heat transfer, turbulence and submarine melting.
These unusual underwater structures add another dimension to the strange ice and snow phenomena created when ice, water, sediment and temperature interact.
The Glacier Changes the Fjord Around It
The researchers did not stop at filming the ice.
Using temperature, salinity, turbidity and stable water-isotope measurements, they traced how glacier-derived freshwater mixes and spreads through the fjord.
Measurements made only about 300 meters from the terminus were already smoother than those collected directly beside the glacier, showing just how localized and chaotic conditions at the boundary can be.
Near the ice, the upper approximately 20 meters contained fresher and more turbid water consistent with an outflowing meltwater plume.
Seasonal differences were substantial.
During March, the modeled glacier-meltwater contribution was small. During August, when glacier activity was greater, meltwater signals were much stronger in parts of the fjord, although the highest measured fractions were highly localized and may also have been influenced by melting grounded icebergs or runoff from another glacier.
The important point is that a marine-terminating glacier doesn’t simply add freshwater to the ocean. It mixes, stirs and restructures the surrounding fjord, creating another striking example of how ice interacts with broader ocean and coastal processes.
And This Hotspot Could Disappear as the Glacier Retreats
That makes the discovery important beyond one Greenland fjord.
Marine-terminating glaciers end directly in the sea. Naajat Sermiat is one of the outlet glaciers draining ice from Greenland, where the Greenland Ice Sheet ultimately meets the surrounding ocean system.
But as they retreat, some eventually withdraw far enough inland that their termini leave the ocean completely.
The study notes that between 2000 and 2020, 169 marine-terminating glaciers across the Northern Hemisphere retreated sufficiently to become land-terminating.
When that transition happens, the system changes fundamentally.
Instead of meltwater being injected beneath the ocean surface and rising through the water column, freshwater reaches the sea mainly at the surface after traveling across land.
The glacier also stops delivering solid ice directly into the marine environment.
That means the intense glacier-ocean mixing occurring directly at the terminus disappears with it.
And according to the researchers, so could the biological hotspot they discovered.
That could affect local food webs, nutrient cycling, carbon fluxes and ultimately coastal ecosystems — including ecosystems supporting fisheries important to Greenland communities.
A Glacier Is More Than Melting Ice
The most fascinating part of this study may be how dramatically it changes the view of a glacier terminus.
From above, the boundary appears simple:
ice ends; ocean begins.
Underwater, the robot revealed something entirely different.
Freshwater erupts from beneath the glacier. Sediment cascades from the ice. Turbulent plumes rise through seawater. Krill swim toward them. Fish gather nearby. Worms occupy sediment on the glacier. Jellyfish, squid, shrimp and other animals move through the boundary zone.
All of it is happening against a moving wall of ice hundreds of feet deep.
The researchers describe Naajat Sermiat’s glacier-ocean boundary as a previously unrecognized ecological hotspot.
And because direct observations of these dangerous environments remain rare, it raises an obvious question:
How many similar ecosystems are hiding along the submerged edges of Greenland’s glaciers?
Greenland Glacier Biological Hotspot: FAQ
What did scientists discover at the Greenland glacier?
Scientists using an underwater robot at Naajat Sermiat in South Greenland discovered an unexpectedly rich concentration of marine life directly beside the submerged glacier front, including large aggregations of krill, fish, shrimp, squid, jellyfish, worms and other organisms.
Where is Naajat Sermiat?
Naajat Sermiat is a marine-terminating glacier in South Greenland. Its glacier front extends directly into seawater, creating an unusually dynamic boundary between ice and ocean.
Why was so much marine life found beside the glacier?
Glacier meltwater can drive circulation that moves nutrients through the fjord. Researchers also observed krill swimming toward subglacial discharge plumes, raising the possibility that microbes and organic material transported from the glacier provide an additional food source.
What animals were found there?
The underwater observations documented krill, capelin, cod, copepods, amphipods, Mysis, shrimp, squid, jellyfish, crab larvae, chaetognaths, worms and other marine organisms.
Can glaciers support marine ecosystems?
Yes. Marine-terminating glaciers can release freshwater, sediment and nutrients while driving circulation that transports deeper nutrient-rich water upward. The new observations suggest the glacier-ocean boundary itself can also become a concentrated biological hotspot.
Why could these biological hotspots disappear?
When a marine-terminating glacier retreats onto land, direct interaction between its ice front and seawater ends. That can remove the mixing, subglacial discharge and other glacier-ocean processes that help create these unusual ecosystems.
The Study
The research was led by Fleur Rooijakkers of the Center for Ice-Free Arctic Research at Aarhus University, together with Lars Ostenfeld, Ebbe Poulsen, Antoine Drancey, Nanna B. Karlsson and Søren Rysgaard.
The peer-reviewed study, “Biological hotspot at a glacier ocean boundary in South Greenland,” was published in Communications Earth & Environment on August 28, 2026.
The researchers emphasize that observations directly at glacier-ocean boundaries remain extremely rare because of the technical difficulty and danger posed by calving ice.
That is precisely what makes this robot’s journey so valuable: instead of inferring what might be happening beside the glacier from measurements farther down the fjord, scientists were finally able to look directly at it.
And there was considerably more life there than expected.
Primary source:
Rooijakkers et al. (2026), Biological hotspot at a glacier ocean boundary in South Greenland, Communications Earth & Environment.
Bottom Line
An underwater robot sent directly to the submerged front of South Greenland’s Naajat Sermiat glacier discovered an unexpectedly rich concentration of marine life, including large aggregations of krill, fish, worms, shrimp, squid and jellyfish.
The observations suggest that marine-terminating glaciers may support ecosystems in more ways than previously recognized. Glacier-driven circulation can bring deep nutrients upward, but organisms at Naajat Sermiat also appear to respond to material emerging directly from the glacier.
As Greenland’s glaciers retreat from the ocean onto land, these strange and productive glacier-ocean ecosystems may disappear with them.
