What are the polar regions like?
Seasonal variationsA characteristic of both polar ecosystems is the seasonal formation and melting of this sea ice, a process which has a vital role in feeding the entire polar marine ecosystem. As ice melts it releases nutrients which feed microscopic algae (phytoplankton). This algae provides food for larger animals in the water and at the seafloor. At the melting ice edge, these algae are particularly nutritious and this higher quality is reflected in the health and abundance of animals all the way to the seafloor.Both polar oceans are also separated from warmer surrounding oceans by a polar front, an invisible and mobile barrier where cold polar water meets the surrounding warmer waters, but do not mix. Instead, warmer nutrient rich water rise up from the deep Atlantic and feed blooms of phytoplankton at the surface. Like at the sea ice margin, this phytoplankton is an important source of seasonal food, especially in the spring after months of near darkness during winter.The Arctic polar front is non-continuous as it is broken up by the land, but has a strong influence in the Barents Sea where warmer Atlantic water flows into the Arctic Ocean. In the Antarctic however, this polar front is continuous all around the continent and is associated with the fast moving Antarctic Circumpolar Current. Together they form a physical barrier which separates the Southern Ocean from the surrounding warmer oceans, isolating the species which live within it. You can see these currents in action using this online visualisation tool.
Impact of climate change
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In the next step we will meet some of the animals that live beneath the ice. Before we do, what challenges do you think life faces in these freezing waters?
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