The ringed seal is certainly one of the most important Arctic creatures. This small seal species is the preferred prey of polar bears, but also an important food source for the Inuit. An international research team has now investigated reports from fishermen in Greenland’s ice fjord near Ilulissat who told of an unusual seal species. The result of the investigation was a big surprise.
Larger, heavier, stronger ring coloration on the fur, a stronger habitat fidelity in the ice fjord of Ilulissat and probably a different type of osmoregulation (dealing with the salinity of the seawater), that is Kangiat, the newly described type of ringed seal. These are the findings of an international team of researchers who published their results in the journal Molecular Ecology in mid-October.
Reports of a group of ringed seals that look and behave differently from other ringed seals have been circulating for some time and had caught the attention of Aqqalu Rosing-Asvid of the Greenland Institute of Natural Resources. As a senior researcher, he is interested in the seals around Greenland and therefore followed the information provided by fishermen who had observed these seals in the ice fjord off Ilulissat and had named them “Kangiat” (those from Kangia). Together with Morten Tange Olsen, a molecular biologist from the University of Copenhagen, and Paolo Momigliano from the University of Vigo, and a group of scientists, a total of 24 animals of the special seals were captured, measured, fitted with transmitters and samples taken for genetic analysis.
These samples showed that the seals had began to diverge genetically from ordinary Arctic ringed seals around 240,000 years ago. The differences include not only the appearance or coloration, but also physiological and behavioral aspects. For example, the team found differences in osmoregulation, which means that Kangiat ringed seals are adapted differently to the varying salinity of their habitat than their relatives in other regions. The team of authors hypothesize that a longer exposure to the freshwater environment in the ice fjord over the course of developmental time might be responsible.
Another special feature was revealed when evaluating the GPS data from the loggers. With the exception of a few individuals, the Kangiat ringed seal remained in the ice fjord and hardly ever wandered out into the open sea. The reason for this may be the Sermeq Kujalleq glacier: “Across the Arctic, marine-terminating glaciers, deep fjord systems and polynyas sustain high biological productivity and provide important foraging and resting habitats for marine organisms,” writes the team of authors. They conclude that the genetic differences stem from self-imposed isolation. “They have managed to preserve their characteristic traits despite being a small group,” explains Aqqalu Rosing-Asvid. He estimates that only around 3,000 animals make up the total population of the Kangiat ringed seal. A small number considering that an estimated 1.2 million ringed seals live in the entire region between Canada and West Greenland and that the ice fjord is not actually a closed-off system.
According to the team, the animals are also more aggressive and territorial and they also appear to exhibit different mating and feeding behavior. This makes it more difficult for other seals to mate with Kangiat ringed seals. “The ringed seal from Kangiat is in contact with other ringed seals. Still, it maintains its distinctive features and is therefore referred to as an ecotype, which is very rare among seals,” Rosing-Asvid continues.
The extent of the differences and other unique characteristics of the Kangiat ringed seal still need to be investigated in more detail. How it deals with the changes to its habitat remains also an open question. In the past 150 years, the Sermeq Kujalleq has receded by more than 40 kilometers and this decline continues. In addition, the number of ships crossing the ice fjord for various reasons increases almost annually. Thus, there are still many unanswered questions. For Aqqalu Rosing-Asvid, one thing is clear: without the local population, this unique seal would never have been discovered and it shows that the Arctic still allows spectacular discoveries to be made today if the knowledge of the Inuit is integrated into research.
Dr Michael Wenger, PolarJournal
Link to the study: Rosing-Asvid et al (2023) Mol Ecol 32 (22) An evolutionary distinct ringed seal in the Ilulissat Icefjord, doi.org/10.1111/mec.17163
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