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Delve deeper into hot topics featured in NGM's April Geographica and Who Knew with help from Resources. Click on a link, pick up a periodical, browse through a book, and explore!
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Polynyas: spas for icy life
Beneath ever shifting ice in the polar oceans thrives a rich ecosystem, from plankton to whales. It's hard to see and hard to study. Fortunately, parts of these waters never completely freeze. These ice windows are polynyas—hot spots for life.
Dozens of polynyas perforate the Arctic and Antarctic. Although thin ice forms, the pools are kept fluid by winds, tides, currents, and warm upwellings. Polynyas can be less than a square mile or even larger than the 30,000-square-mile (70,000-square-kilometer) North Water Polynya in the Canadian Arctic, between Greenland and Ellesmere Island.
Flowers appear in the spring as pools of open water expand. Within the polynyas sunlight triggers blooms of algae and phytoplankton, the base of the marine food web. Tiny crustaceans called copepods graze on microscopic marine plants. The copepods feed bowhead whales and arctic cod. The cod in turn are a banquet for belugas and ringed seals.
The North Water Polynya is richer than any other in the Canadian Arctic "because the algae production season is so long, four to five months, and the surface water temperatures are higher," says Louis Fortier, leader of the International North Water Polynya Study. Since the polynya is essentially an ice-free system, Fortier's researchers are also using it as a scale model to study how the entire Arctic Ocean might respond to ice melt amid global climate change.
—John L. Eliot
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