The Arctic is one of the harshest regions of the planet, where life is kept in the most delicate balance. At first glance, this icy world seems silent and empty, but in reality it hides a complex ecosystem where each organism depends on others. Even such powerful predators as polar bears not only play the role of hunters, but also become an important source of nutrition for other creatures.
A polar bear on the ice.
The role of the polar bear
The polar bear is a symbol of the Arctic and the top of its food chain. However, scientists from the University of Manitoba have proven that its meaning is much deeper. Over the course of many years of observation, it turned out that every year polar bears leave about 7.6 million kilograms of prey after hunting. These remains become the main food source for many Arctic species, from Arctic foxes and ravens to bacteria and marine invertebrates.
This interaction forms an entire ecological network: the corpse of a captured seal becomes a point of life for dozens of organisms. Each animal that feeds on leftovers transfers energy further along the chain, connecting the ocean and land.
The researchers identified 11 species that regularly depend on polar bear prey, and another 8 species that benefit indirectly from these residues. Among them are arctic foxes, northern crows, sea gulls, cormorants, petrels, and even bacteria that process leftover meat into nutrients.
This system is like a vicious circle — what a polar bear leaves behind after hunting becomes the beginning of a new life for dozens of other creatures. The polar bear is a seal hunter and a source of carrion. It also links the oceanic and terrestrial food chain.
Arctic foxes feed on the remains of seals and spread organic matter overland. Crows and seagulls collect carrion on the ice and transfer nutrients. Marine invertebrates
they feed on decomposed tissue and convert organic matter into minerals. Bacteria decompose the residues to nitrogen and carbon and finally return the elements to the soil and water.
Ice as a bridge between ocean and land
Sea ice is not just frozen water, but a unique platform on which all Arctic life is built. It is here that bears hunt seals, which means that it is here that the opportunity arises for other species to get food.
When the ice begins to melt ahead of time, this natural “bridge” collapses. Polar bears are losing access to hunting grounds, and as a result, the source of food for scavengers is disappearing. The study showed that the decline in the number of polar bears in two subpopulations has already led to the loss of more than 300 tons of food annually for other animals.
The problem of polar bears is not just a matter of preserving one species, but a signal of disruption to the entire Arctic ecosystem. The fewer bears there are, the less carrion birds and arctic foxes eat. Without them, the balance between reducers, detritophages, and predators is disrupted.
This is a classic example of an ecological domino: the disappearance of one link leads to the destruction of the entire chain. The Arctic lives by interdependence, and the loss of even one participant can change it forever.
When a bear abandons its prey, small scavengers and birds take over. The bones and remains then become a breeding ground for bacteria and invertebrates. These, in turn, enrich the soil and water with elements necessary for the development of algae and plankton. As a result, the energy that started its journey in the seal’s body returns to the ocean, closing the cycle.
Advantages of the Arctic ecosystem: high adaptation of organisms, efficient use of food residues, a closed metabolic system, mutual assistance between species. And the cons: extreme dependence on climate, limited resources, vulnerability when a key link disappears, disruption of the chain when ice is lost.
An increase in temperature leads to a rapid reduction in ice areas. Polar bears are increasingly finding themselves on the shore, where seal hunting is impossible. Every year they have to travel longer and longer distances in search of food, losing energy.
By Mikhail Gavrilov
