Ringed Seals
Ringed Seal
If you ever find yourself in Northern Canada, looking for a cute animal to distract you from the raging cold, look for none other than the Ringed Seal. Ringed Seals (Pusa hispida) are by far the most common seals found in Canada, and additionally have a wide range encompassing the entirety of the northern arctic waters of the world (See Map). However, despite their large range, they are intensely constrained by the degree of ice coverage. Ringed seal habitat requires a large ice cover, especially during the mating season, as pups are ‘raised’ on the ice itself.
Despite its small size (being the smallest species of seal), their importance and impact on both wild ecosystems and on human populations is substantial.
A relatively solitary species, the Ringed Seal spends its days hunting for a variety of prey, including cod (arctic and polar) and small crustaceans, diving down to depths of 45m to catch prey. Unfortunately for the seals, they not only seek out prey for food, they are themselves the prey of several top predators. These seals are preyed upon by polar bears, occasionally killer whales, and as pups face danger from arctic foxes.
Additionally, ringed seals have long been a staple part of the indigenous people of the arctic. Specifically in Canada, ringed seals were once (and still continue to be) a highly important dietary component to the Inuit people, as it is not a seasonal, but a year-round food source.
Not only are they cute to look at, ringed seals are also an integral part of Northern Canada’s wildlife ecosystem, and a significant food source for many humans themselves.
Ringed Seal distribution shown in lighter shade
The perils of Breathing
The never ending race between predator and prey is seen in nearly all living things. Being a mid-level predator, the Ringed seal must both hunt other living things (they prefer arctic and polar cod), but must also face the possibility of becoming the prey themselves. To the ringed seal, the polar bear is their arch nemesis.
The predator-prey interactions seen between the ringed seal and the polar are of particular interest due to the limited variety of food sources available to the polar bear in the Canadian North. Living in harsh northern climates, polar bears rely heavily on ringed seals to meet their energy requirements. As the ringed seal is found along the shores/edges of ice flows virtually year-round, they are a prime target for hungry polar bears.
Breathing hole created and maintained by seals
To start investigating this predator-prey relationship, it is first important to look at the lifestyle of ringed seals. These seals, as previously mentioned, maintain a habitat along ice flows, and require full ice cover for survival. Feeding mainly on fish and small invertebrates, the seals swim and hunt beneath the ice in the frigid arctic waters. As mammals, they breathe air, and therefore despite their mainly aquatic lifestyle, must continually come up to the surface for air. With clawed front flippers, the seals are capable of maintaining cone-shaped breathing holes within the ice flows.
It is at the site of these breathing holes that the seals most often lose the battle with polar bears. As the bears are greatly outmatched in swimming ability, they rely on the seals need to surface for air to facilitate their hunting (polar bears are also known to respond to the underwater vocalizations of ringed seals to determine their location). However, the seals do have some defenses. Ringed seals are know to blow little air bubbles up just beneath a breathing hole, in order to ascertain whether a polar bear is present. And as said before, when within the safety of the ocean, the seals can easily out-swim the large bears.
Unfortunately, the ever-present danger of polar bears in one to which the seals have little defense. The relatively low numbers of polar bears in comparison to the number and range of ringed seals is what keeps this food-web in motion.
For the ringed seal, it is simply dangerous to breathe.
Ringed Seals in 25 years: Grim at best
In a world with an ever changing future, speculating the future of any given species can be a challenge. But in the case of the ringed seals, their future is dependent mainly on one giant factor: climate change. There is no doubt that climate change has been a hot topic for years, and has been associated with a huge number of species projections. However, for ringed seals, the effects of climate change are not minute, not inducing a change in range, or a shift to a new food source. No, for the ringed seals, climate change could be devastating. As the temperatures increase in Northern Canada, the very ice upon which they depend is slowly melting from right beneath them. Without a solid ice cover, including snow coverage as well, the pups cannot survive. Even today, ringed seal populations have been impacted negatively by the climate change experienced to date. And in 25 years? How much ice will be left? How far north will these small seals have been pushed? It is not only the pups which are affected by the ice cover, but the adults as well, leading to devastating population decreases as a result of melted ice.
Decreasing Ice Coverage
Sadly, unless temperature increases seen to date are altered, the fate of the ringed seal is not optimistic. It is not new information that arctic species are the most affect by climate change, as there is only so far north that you can go. As the seal populations decrease, so will several other species, including the iconic polar bear.
How drastic will these population changes be in 25 years? No one can say for sure, but with no ice, there will likely be no seals.
References
Cushing, B.S., Cushing, N.L., and Jonkel, C. (1987). Polar Bear responses to the underwater vocalizations of ringed seals. Polar Biology. 9:2, 123-124. Online: http://www.springerlink.com/content/h063850257q4l016/
http://animals.nationalgeographic.com/animals/mammals/ringed-seal/
http://www.wildernessclassroom.com/polarbear/2009/03/ringed-seal.html
http://www.onegreenplanet.org/animalsandnature/animals-most-drastically-affected-by-climate-change-part-2/attachment/ringed-seal-climate-change/
http://news.nationalgeographic.com
