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The Threat of Climate Change to Walrus; a Keystone Species in the Arctic Marine Ecosystems

Despite extreme cold and difficult living conditions, the Arctic is home to many species that are endemic to this region such as Polar Bear, Arctic Fox, Walrus, etc. More than 21,000 species of fish, birds, mammals, invertebrates, plants…

Priyakshi Sarma · 4 min read ·

Despite extreme cold and difficult living conditions, the Arctic is home to many species that are endemic to this region such as Polar Bear, Arctic Fox, Walrus, etc.

More than 21,000 species of fish, birds, mammals, invertebrates, plants, fungi, and microbe species can be found here. These species are highly adapted to the harsh environment of the Arctic. They provide essential services to the people, maintain a balance around the globe, and also contribute to the healthy functioning of the global ecosystem.  However, they are under threat due to climate change and anthropogenic activities; the former being of the biggest concern. One such species under threat is Walrus, often regarded as a keystone species (a species having a large effect on its natural environment) in the Arctic marine ecosystems.

First, let us know some facts about Walrus. The only species in the family Odobenidae and genus Odobenus, Walrus; a large marine mammal with flippers, a broad head, a short muzzle, small eyes, whiskers, and tusks; is subdivided into two subspecies: The Atlantic Walrus, that lives in the Atlantic Ocean (Canada’s eastern Arctic, Greenland, Russia, and Norway), and the Pacific Walrus, which lives in the Pacific Ocean (Coasts of Eastern Russia and Alaska). Their tusks are mainly used for defense, coming out of the water, and making holes in the ice for breathing. They mostly live in shallow waters and forage on the sea floors.  

In order to collect food, Walruses dive and look for worms and clams by churning up the soft layers of silt and sediment with their muzzles and whiskers and in the process release nutrients deposited in the sediment, decomposing material, larval fish and crustaceans from the seabed. This way it enriches the sea water and provides food for bigger fish, bigger crustaceans, and also to commercial fishermen, seals, seabirds, and polar bears. Thus it is a keystone species in the Arctic as its presence is important in maintaining the ecological balance of its habitat. It has cultural significance also for the people of the Arctic.

However, due to climate change and global warming, its habitat is shrinking due to the melting of ice, thereby threatening its existence. Roughly 13% of the summer sea ice of the Arctic is disappearing per decade and is warming almost three times faster than the rest of the world. Walruses use sea ice for foraging and nursing their young ones. They are more dependent on Sea ice than Polar Bears. Chukchi Sea, the habitat for Pacific Walrus, is disappearing from beneath as the sea ice continues to melt due to global warming, forcing the Walruses to haul-out (mass congregation) of the ocean and live temporarily on land in the spring.

The first such haul-out was observed in Alaska’s Point Lay in 2007. At that time the Arctic Sea ice in the summer reached its second-lowest minimum extent in recorded history. As the extent of the sea ice in summer continues to decline, the haul-outs of Walruses into the land has increased considerably. These large haul-outs are extremely dangerous to the Walruses as they get frightened by any noise (airplane, humans), which results in a deadly stampede.

According to many studies, it is predicted that the Arctic Summer ice could be ice-free by as early as 2040 which would mean Walruses would have to spend more time on land, resulting in less access to their prey, increase mortality due to stampedes and increase human-wildlife conflict. Walruses like to feed on Clams and Clams feed on algae that grows on the bottom of the Sea ice.

As the Sea ice continues to melt, the number of algae dropping down to the bottom will decrease, which will eventually decrease the population of Clams. Also, an increase in global warming results in more carbon absorption by the oceans; which act as carbon sinks. An increase in carbon absorption by the oceans results in Ocean Acidification, which will decrease the population of Molluscs; one of the main food sources of Walrus.

The International Union for the Conservation of Nature says “Although the global population is undoubtedly still quite large, there is evidence of declining populations in two of the subspecies. Climate change is expected to have negative consequences for Walruses, and particularly severe consequences for the Pacific subspecies”.

Research is going on to study the effects of climate change on Walruses by many organizations like WWF, British Antarctic Survey, etc. 
Thus Climate change is putting pressure on Walruses and many other Arctic species as more and more Sea ice is melting. Urgent actions are needed to reduce greenhouse gas emissions and ultimately global warming. 
This planet belongs to each and every species that exists. So the survival of every species is important for the proper functioning of the global ecosystem.
 
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