The Arctic Food Web: How Energy Flows Through the Polar Ecosystem

Every ecosystem can be understood as a network of energy transfer — solar energy captured by photosynthetic organisms at the base of the food web, passed up through successive levels of consumers, with energy lost at each transfer as heat. The Arctic food web is distinctive in its relative simplicity compared to tropical ecosystems — there are fewer species at each level, making the connections between them more direct and the system more vulnerable to disruption at any point. Understanding how energy flows through the Arctic food web is essential to understanding why the loss of any key species or habitat type can cascade through the entire system.

From Sunlight to Polar Bear

The Arctic food web begins with photosynthesis — the conversion of sunlight and CO₂ into organic matter by ice algae and phytoplankton. These primary producers support zooplankton — particularly the copepod Calanus hyperboreus, one of the most energy-rich zooplankton species in the world, which stores enormous quantities of lipid-rich oil that makes it an exceptionally nutritious food source for the organisms that consume it. Arctic cod (Boreogadus saida) occupy the critical middle position in the food web — consuming zooplankton and in turn being consumed by seals, beluga whales, seabirds, and larger fish. Ringed seals are the primary prey of polar bears, completing the energy pathway from ice algae to apex predator.

Climate Disruption of the Food Web

Climate change is disrupting Arctic food web dynamics through multiple simultaneous pathways. The decline of sea ice reduces ice algae production — diminishing the energy input at the base of the food web. Warming waters are shifting the distribution of zooplankton and fish species — with some cold-adapted Arctic species being displaced by sub-Arctic species moving north. Phenological mismatches are emerging — the timing of peak plankton production, fish hatching, and seabird breeding becoming increasingly misaligned, so that predators arrive to find their prey at a different stage of their cycle than expected. These disruptions compound each other in ways that are difficult to predict but are already visible in declining populations of ice-dependent species.