Are White Whales Resilient to Climate Change?

As global warming increases, cold regions like the Arctic continue to experience great shifts in climate and environment. The effects of these shifts are closely observed in human populations, but how are different species impacted? A recent study examined white whales in Svalbard, Norway, and the climate change effects on their behavior and diet. Researchers looked at how reduced sea-ice formation and melting tidal glacier fronts influence the changes in habitat and movement patterns for this species.

White Whale Background and Observations

White whales, also known as beluga whales, can be found in the circumpolar Arctic. They’re known for their distinct white color and are one of the smallest whale species in the world. They are sometimes referred to as “sea canaries” for their high-pitched calls. With an estimated 150,000 individuals globally, they are listed on the IUCN Red List of Threatened Species. Some local populations such as those located in Cook Inlet, Alaska, are considered critically endangered.

White whale spotted in the Arctic and sub-Arctic (Source: Dennis Jarvis/Flickr)

These whales remain off the Svalbard coasts year-round. They live in sea-ice fjords and tidal glacier-front habitats. The fjords are sheltered from open-water predators, human activity, and extreme weather, making them particularly ideal for juvenile mammals. Tidal glacier-fronts are prime foraging areas for the whales. These regions have fresh water ideal for polar cod and capelin, two fish that make up a large part of white whale diet.

White whales migrate seasonally, some travelling 10s of kms, others as far as several hundred. During the warm summer season, sea ice in the fjords melts, providing an opportunity for the whales to move and feed in this region. Sea ice formation in the winter pushes the whales out toward the glacier-front habitats, where they spend most of their time during the colder season.

Methodology and Sampling

Increased warming is expected to negatively influence the environmental composition of this region. Svalbard has the greatest decrease in seasonal sea-ice cover in the circumpolar Arctic region. Rapid increase of air and sea water temperatures over the last two decades are the major contributing factors to this change. According to researchers, glacier-front melting and the associated reduction of foraging habitat could lead to changes in diet. Less sea-ice formation in fjords and warmer seasons could also affect biodiversity in these habitats. Could this mean white whales will need to migrate elsewhere for feeding during warmer seasons?

Researchers in this study compared habitat and movement changes of white whales, before and after major warming induced changes in the environment. They believed these changes began in 2006, so the two study periods were 1995-2001 and 2013-2016.

Fortunately for the researchers, satellite data from earlier years was available. They used satellite tracking to take measurements of whale movement patterns for the later period, and were then able to compare movement patterns for both periods. To track movement, white whale groups were live-captured using a nylon net and then tagged.

Researchers tagging a whale for observation (Source: Kit M. Kovacs)

GlacierHub interviewed Kit M. Kovacs, one of the study’s authors and a senior research scientist at the Norwegian Polar Institute. Kovacs explained that choice of methods reflected concerns for animal welfare as well as data gathering. Groups without calves were netted, to prevent possible injury to young whales, she said. A total of 38 adult individuals were sampled for the study, 34 of them being male. Kovacs also explained that the females travel with their young, while adult males tend to travel in all-male groups, which would explain the sampling bias.

Research Findings and White Whale Resiliency

Results showed that during the later tracking period, the whales continued to remain close to the Svalbard coast. Scientists found this behavior to be striking, particularly when looking at populations in other areas that move long distances. The whales remain close to Spitsbergen, one of the largest islands in Svalbard. They move from the west coast fjords in the summer toward the east coast in the winter. The greatest distance of movement occurred when individuals were forced off the coast by the winter formation of landfast sea ice.

Ice front at a Spitsbergen glacier (Source: Paul/Flickr).

Some changes in habitat were observed. Whales were found to spend much time in glacier-front habitats for both periods, although they now spend more time out in the fjords. Less sea ice formation in the fjords has allowed for an influx of fish species that prefer the warmer waters. Arctic fish, particularly polar cod, have declined in numbers in this habitat, and are being replaced by Atlantic cod, haddock and herring. This new fish composition could be attracting the whales to fjords during the warm season.

Kovacs explained how a change in diet could affect the whales. “White whales use a pretty broad array of food types across their range, so it is unlikely to be a big deal for them to switch to new fish types. They might have to eat more, if the new fishes have a lower fat content, just to keep the same energy intake. As long as enough are available, it should not change their annual intake,” she said.

The white whales’ ability to consume a variety of food resources proves to be beneficial to the species. This helps them build resilience against some of the extreme effects of warming. The beluga may be able to adapt to an environment with less ice than in the past due to this dietary flexibility. Other species may not be so fortunate.

Observing Glacier Calving through Time-Lapse Imagery and Surface Water Waves

A recent paper published in the Journal of Glaciology explores how a team of researchers studied waves in a Patagonian lake to detect glacier calving events at Glaciar Perito Moreno. Calving events occur when an iceberg detaches from the glacier front. Such events produce waves of different magnitudes as the glacier discharges into the ocean or an adjacent lake.

The paper’s lead author, Masahiro Minowa, told GlacierHub that while calving plays a key role in the recent rapid retreat of glaciers around the world, many processes related to calving are still poorly understood because direct observations are scarce and challenging to obtain.

An example of a glacier calving event producing surface tsunami waves (Source: Masahiro Minowa)
An example of a glacier calving event producing surface tsunami waves (Source: Masahiro Minowa).

Minowa and his team employed a creative methodology to observe calving events at a distance. Employing four time-lapse cameras and a water pressure sensor, they conducted fieldwork in three separate time periods, roughly one week to three weeks long between 2013 and 2016. 420 events were noted within this relatively short period of time. They also estimated the calving volume using the time-lapse images and maximum wave amplitude.

“We did our field works twice in summer and once in winter so that we could observe the seasonality of calving activity. We also wanted to understand mechanisms driving calving if there are any,” Minowa said.

The researchers categorized the time-lapse images by separating calving events into four groups: 1) Topple, an ice tower toppling into the lake; 2) Drop, an ice block dropping into the water; 3) Serac, a small piece of serac slipping down to the lake; and 4) Subaqueous, an underwater iceberg detachment that floats up to the lake surface.

Illustration of the most common calving types at the study site (Source: Minowa et al)
Illustration of the most common calving types at the study site (Source: Minowa et al).

These images were then scrutinized in great detail. For example, Topple and Drop events were distinguished based on whether crevasse widening occurred; while Subaqueous was differentiated from other subaerial events by noting a relatively large single iceberg appearing without any geometrical change on the glacier front and a lack of sediment inclusion on the surface.

The surface wave profiles corresponding to the events were also examined. Their signals were more complex, making it difficult in some cases to distinguish events on the basis of wave profiles alone.

“Initially, we expected a clear difference in wave frequencies between subaqueous and subaerial events. While we could see some difference in frequencies, we are unsure if this is a result of different calving style,” Minowa explained. Wave frequencies also vary based on the relative location of the event to the sensor, even if it is the same calving style. A larger sample of cases is thus required to confirm the wave patterns associated with different calving events.

However, Minowa stressed the importance of choosing a strategic location for the water pressure sensor, which vastly affects the results and findings of a glacier calving study. He warned that a problem may arise from the instrument’s location. “Since waves’ amplitude decay with distance, you will not be able to detect all of the calving events if you place the sensors too far. So, you need to be close enough to the glacier, and you will easily detect many of them,” he said. Yet, this might limit the scope of the area studied, requiring a balanced consideration.

Examples of the time-lapse camera images (Source: Minowa et al)
Examples of the time-lapse camera images (Source: Minowa et al).

From the data, the team could see the seasonality of calving activity. Their results showed that calving events were 2.6 times more frequent during the austral Summer (December-March) as compared to Spring (October). Subaerial calving events occurred 98 percent of the time, although Minowa conceded that the dataset was a bit short to confirm any trigger mechanisms.

Following the research, the team is now ready to install new water sensors for a year-round measurement around the glacier in the hope of further understanding calving processes through the use of surface-waves in glacier fronts. This is a step toward reducing glacier melting in Patagonia and the rest of the world.

Roundup: Western Canada, Supercooled Water and Seaweed

Glacier Change: Dynamic Projections

canadian

“Mountain glaciers around the world are in decay. According to a modelling study that — unusually — includes full ice flow physics, those in Western Canada will largely be restricted to the coastal region by the year 2100.”

See more about this article here.

 

Supercooled Water near the Glacier Front 

Norway

“Measurements of temperature and salinity were performed in the immediate vicinity of Paula Glacier in the Rinders Fjord (Spitsbergen) in March 2013. At a distance of 15 m from the glacier, we found water with significantly smaller salinity than the surrounding waters. The water temperature appeared 0.35°C lower than the freezing temperature.”

Read this article here.

 

The Impacts of Glacier Retreat on Seaweed Growth

seaweed

In Potter Cove, Antarctica, newly ice-free areas appeared due to glacial retreat. Simultaneously, the inflow of sediment increased, reducing underwater photosynthetically active radiation (PAR, 400–700nm).

Read more here.