At Glacier’s End: Protecting Glacial Rivers in Iceland
“Page after page of curving colorful rivers delight the eye in At Glacier’s End, a recently published book about Iceland’s glacial river systems. The images that lie behind its cover were created by Chris Burkard, a photographer and explorer, and the more than 8,000 words that tell their story were penned by Matt McDonald, a storyteller and traveller.”
“Our main goal with the book was to advocate for Iceland’s national parks and to try to create a voice for them from a visual perspective,” Burkard said in an interview with GlacierHub. “In Iceland, it’s really surprising, many politicians who are the decision-makers haven’t had a chance to actually see [these places] because they are far away and really hard to access.”
Seabirds Find New Ways to Forage in a Changing Arctic
“On Arctic landmasses, valley glaciers––formally known as tidewater glaciers––run all the way to the ocean, where cloudy plumes from their discharge create the perfect foraging habitat for seabirds. Researchers found some birds are reliant upon the turbid, subglacial freshwater discharge, which breaks apart icebergs and forms a column of freshwater foraging ground at the glacier’s edge, while others prefer to forage near the broken sea ice where water is less turbid…In 2019, Bungo Nishizawa and associates published a study in the ICES Journal of Marine Science that investigated the effects of subglacial meltwater on two assemblages of seabirds in northwestern Greenland.”
Read the full story by GlacierHub writer Audrey Ramming here.
A First-ever Look at Ice Stream Formation
In this week’s Video of the Week, the world gets its first-ever look at ice stream formation. The video, which was published on the American Geophysical Union’s (AGU) YouTube channel on December 17, tracks the rapid movement of the Vavilov Ice Cap, in the high Russian Arctic, from summer 2015 to summer 2018. In the video the glacier’s speed is color-coded by meters per day of movement in what scientists believe is the first documented transition of a glacial surge to a longer-lasting flow known as an ice stream.
On Arctic landmasses, valley glaciers––formally known as tidewater glaciers––run all the way to the ocean, where cloudy plumes from their discharge create the perfect foraging habitat for seabirds. Researchers found some birds are reliant upon the turbid, subglacial freshwater discharge, which breaks apart icebergs and forms a column of freshwater foraging ground at the glacier’s edge, while others prefer to forage near the broken sea ice where water is less turbid.
In 2019, Bungo Nishizawa and associates published a study in the ICES Journal of Marine Science that investigated the effects of subglacial meltwater on two assemblages of seabirds in northwestern Greenland. One group included foraging surface feeders like the black-legged kittiwake. The other was comprised of divers, like the little auk. The researchers found that while the surface feeders congregate in the area of the cloudy plume, divers prefer to search for food where the water is less cloudy, spatially dividing the bird groups near the edges of glaciers.
Françoise Amélineau, a researcher of seabird ecology at the Norwegian Polar Institute, published a study in Scientific Reports last year, presenting the results of a 12-year monitoring program in East Greenland, which analyzed biological parameters of the little auk, the most common seabird in the Atlantic Arctic. Amélineau says that little auks use vision to detect prey and because meltwater plumes are so cloudy, the birds tend to forage farther offshore in clearer water, where they dive more than 20 meters below the surface.
A 2013 study in Polar Biology noted that little auks inhabiting West Spitsbergen, Norway also preferred to forage in clear water, far from glacier fronts, where they could easily identify water masses containing large, energy-rich prey.
Little auks usually feed in cold waters at the edge of sea-ice, up to 150 km away from their colonies. “In our Greenland study, we looked at sea ice concentration because some of the prey consumed by little auks are sympagic (associated to the sea ice),” said Amélineau, and “the little auks performed shallower dives in the presence of sea-ice, probably to feed on ice-associated amphipods”––a small type of crustacean. However, these ice-covered feeding areas are disappearing as the climate warms, which could make foraging more difficult.
Not only does a warming Arctic affect the presence of sea ice, it also alters the distribution of the little auk’s prey. Little auks feed on large zooplankton, which remain at depth in clearer waters. As the Arctic warms, the smallest (and lower calorie) Atlantic species of zooplankton is extending northward, threatening the range of the two larger (and higher calorie) Arctic species that little auks prefer. The invasion of the small zooplankton has the potential to negatively affect the fitness and breeding success of the little auk, which is thought to have the highest metabolic rate of all seabirds due to its small size and large flying and diving range.
With sea ice disappearing, the fate of little auk survival may be at risk. However, little auks from a colony of Franz Josef Land, located in the Russian Arctic, are actually taking advantage of a glacial meltwater plume––an adaptation that could be crucial. “We show that in Franz Josef Land, little auks have changed their foraging behavior with sea-ice retreat and the increase of glacier meltwater volume. At this site, they foraged at the glacier meltwater front instead of at more distant feeding grounds near the sea-ice because it allowed them to make shorter foraging trips,” Amélineau told GlacierHub.
Amélineau explained that “at the glacier front, zooplankton is stunned by cold and osmotic shock at the boundary between glacier melt and seawater, which makes it easier for little auks to catch. It probably concentrates their prey closer to the colony, but according to Nishizawa’s study, if the turbidity of the water is too high, meltwater plumes become unfavorable foraging areas for little auks who use vision to detect prey.” Discharge mechanisms can differ between glaciers, and this may be why little auks are able to utilize the Franz Josef Land differently than in Greenland, Amélineau added.
Black-legged kittiwakes are the most common type of gull in the world. While they do consume large zooplankton and small crustaceans, they mainly prefer to eat small fish and other marine invertebrates. While they are the only type of gull that dives and swims underwater, they make very shallow dives compared to that of the little auk, and are unhindered by turbid water.
Turbid subglacial discharge, which is unloaded 10-100 meters beneath the surface of the water, upwells at glacial fronts to form plumes that bring zooplankton, as well as marine worms and jellies from depth to the water’s surface. “The foraging behaviour of kittiwakes observed in the tidewater glacier bays revealed them to be swarming over the subglacial discharge, with rapid simultaneous nose-diving and plunging into the surface water in pursuit of rising prey,” according to one study in Scientific Reports.
While the size of meltwater plumes at glacial fronts are increasing with climate warming in the Arctic, apparently benefitting surface feeders, it is also important to consider the stage of glacial retreat. Kittiwakes, as well as other surface feeders, benefit most from deep tidewater glacier bays because they have strong discharges that upwell prey to the surface over a wide area.
According to the IPCC, the Arctic is warming twice as fast as the rest of the world. “While other species may be able to shift their distribution to higher latitudes or altitudes,” Amélineau said, “Arctic species may not find suitable habitat anymore.”
This is both ecologically and culturally concerning.
While little auks are ecologically considered a keystone species in the Arctic, they are also culturally important to the Indigenous peoples that live there. “They are hunted in Greenland,” Amélineau told GlacierHub. The Inuit “prepare a food called kiviak, where the little auks are fermented for 3 months in a seal skin!” Approximately five hundred of these birds are stuffed, whole, into the skin, and left in a pile of stones to ferment over the winter. They are a popular treat on weddings and birthdays.
Biological responses to changing climatic conditions are difficult to predict, particularly in remote locations that are already heavily impacted like the Arctic, where the ecosystem is already impacted by ongoing sea-ice decline and warming. Amélineau says this makes long-term seabird monitoring efforts extremely important, especially as these birds can be seen as ‘sentinels’ of what will happen at lower latitudes.
In July of 2013, a team of scientists from France, Russia and the United States descended upon an uninhabited archipelago in the Russian Arctic called Franz-Josef Land, the northern most archipelago in the world. There they spent two months at Tikhaya Bay on Hooker Island, one of the archipelago’s 191 islands, tagging and studying a small black and white seabird called the little auk (Alle Alle), which nests on cliffs and dives for its dinner in the frigid water.
Their findings call into question some models of climate change impacts on polar ecosystems, says David Grémillet, the lead scientist of the group, in research published in Global Change Biology in mid-January.
Given its remote high-Arctic location, Franz-Josef Land has long been considered a kind of Arctic Eden, sheltered from the impacts of climate change. Nearly 85 percent of its land mass is blanketed by glaciers and its islands are surrounded by extensive sea ice. But temperatures in the Arctic are rising, and are predicted to increase by as much as 14 degrees Fahrenheit by the end of the century. Grémillet and his colleagues wanted to measure how the ecosystem of this icy Arcadia is responding.
They chose the little auk as a subject because it is a so-called sentinel species, one that can be used as a proxy for the health of an entire ecosystem, much like the polar bear. The most abundant seabird in the Atlantic Arctic, with over 40 million individuals, the little auk is a major part of the food chain in polar ecosystems. Previous research has suggested that the little auk is quite flexible in the face of changes to its environment. But Grémillet and his colleagues suspected the bird might reach a breaking point due to its high energy costs and metabolic rate, as well as a diet primarily made up of copepods—tiny crustaceans that are themselves highly reactive to changes in sea ice and water temperature.
Using remote sensing data, the scientists measured changes in the volume and area of sea ice and glaciers between 1979 and 2013. They also tagged a number of little auks from one colony with tiny electronic devices affixed to legs or breast feathers to track their foraging behavior. These devices, called miniaturized temperature–depth recorders, provided information on the depth and duration of every dive, as well as the hours spent each day gathering food. The researchers then compared current and historical data on the diet, body weight and chick growth of little auks at Franz-Josef Land.
The data they collected revealed some bad news and some good news. The bad news: Sea ice in the Franz-Josef archipelago has, in fact, retreated markedly during the last decade, disappearing entirely during summer by 2005—a harbinger of future conditions elsewhere in the Arctic Ocean. Coastal glaciers have also retreated, dumping large volumes of meltwater into the sea. The good news: while disappearing sea ice curtailed the birds’ traditional feeding grounds, retreating glaciers created new ones. The little auks adapted their behavior, feeding at the boundaries where glacier melt discharged into coastal waters at Tikhaya Bay, close to the their breeding areas. Local zooplankton were shocked by cold temperatures and dramatic contrasts in salt concentrations between the fresh meltwater and saline oceans, making them easy prey. The little auks were able to maintain chick growth weights, while adults lost just 4% of body mass.
The little auks’ adaptability in Franz-Josef raises questions about previous research on the birds. In a 2010 paper, Nina Karnovsky of Pomona College predicted that 40% of all little auks would disappear from the Atlantic Arctic by the end of the 21st century, Grémillet and his colleagues note. They argue that this prediction must now be revisited. They also call for further study of little auks at other Arctic geographies, to see if they are as adaptable as the ones making a home at Franz-Josef Land.
The Franz-Josef little auk findings support the conclusions of other recent research on Adélie penguins in the Antarctic and seabirds and marine mammals in Alaska that suggest glacial melt can, in some cases, compensate for disappearing sea ice to support new feeding habits, benefitting certain animals within an ecosystem, according to the authors of the paper.
“There is currently a huge demand for predicting the fate of Arctic biodiversity exposed to ongoing climate change,” the authors write. “At the species level, this is achieved by building habitat models.” But if the models don’t take certain environmental interactions into account, inaccurate predictions will be made.
For other stories about birds on glacier-covered islands at high latitudes, look here and here.