Loss Of Arctic Sea Ice Endangers Entire Ecosystem, Up To The Great Beluga Whale

The recent report on Arctic sea ice levels underlines the grave impact of global warming on marine creatures that depend on the polar ice cap for survival. Rising temperatures in the far north give way to a rapidly reducing ice cover, and when the sea ice is threatened, so is the phytoplankton it sustains.

Shrinking sea ice means the microscopic algae have less and less room to grow, and the inevitable plankton shortage takes its toll on the rest of the ecosystem, affecting animal species that thrive on sea ice algae.

The dramatic loss of arctic ice floes, which are no longer forming as abundantly over the winter, limits the surface on which algae can grow and, without sea ice or phytoplankton, marine wildlife faces a food deficit and the restriction of both hunting and birthing grounds.

Whole Arctic Food Web Disrupted

Studies show sea ice algae sustain the entire arctic ecosystem. When the base of a food chain is affected, all the other species that depend on it (and on each other) soon follow.

Normally, this time of the year marks the beginning of arctic spring, which typically sets the conditions for algae to bloom. Phytoplankton feeds zooplankton, microscopic animals that make up the primary food source for fish, which in turn are a common prey for seals.

Months later, when temperatures get warmer and sea ice starts to melt, phytoplankton subsides to the sea floor, where it is consumed by worms and other small creatures. These are then eaten by benthic fish – species living on the bottom of the sea – that support the beluga whale population.

Researchers have already noticed the dwindling phytoplankton is causing a decline in zooplankton species, with dire consequences on surface fish that usually hunt them. The Greenland halibut, one of the benthic fish species whales feed on, is also receding, probably because of lack of food.

This fragile ecosystem depends entirely on phytoplankton, which owes its existence to the arctic sea ice. Found at a new record low by this year’s measurements, the ice coverage could potentially disappear during summer, seeing its last bastions in Greenland fjords or the Svalbard archipelago. The snowball effect on arctic wildlife is conceivably catastrophic.

How Does This Impact Beluga Whales?

Beluga whales are already under monitoring by the International Union for the Conservation of Nature, giving the species’ high risk of endangerment. Apart from whaling and contaminated water, climate change adds to the list of threatening factors, altering the whale’s hunting patterns and lifestyle.

“These creatures are in the frontline of change in the Arctic and it is clear they are having to make considerable changes in behavior to survive,” says Thomas Brown of the Scottish Association for Marine Science.

After studying beluga whales for a number a years, Brown discovered belugas have been forced into new hunting territories, venturing farther into the open to catch prey.

Since the whales normally rely on Greenland halibut populations, the decreasing number of fish – which no longer find the same amounts of zooplankton and phytoplankton at their disposal – has pushed belugas into open waters, signaling “a clear shift in the food web and ecosystem in this part of the Arctic Ocean.”

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