Sea-Ice Organisms Face Human Threats

Sea ice, frozen seawater, is more than a “white desert” in the Earth’s polar regions. The solid part of sea ice is mostly pure ice, similar to what you could make by putting tap water in a freezer. It also contains an intricate network of pores, pockets, and channels—known as a brine network—which develops each season. The brine network is filled with a very salty solution that contains nutrients that ice-associated organisms (bacteria, algae, and small animals) use as food. Algae are especially important because they remove carbon dioxide from the atmosphere and provide some of the oxygen we breathe every day. However, ice organisms are witnessing the consequences of human pollution and climate change. Although the polar regions are located far from human areas, the ocean circulation carries pollutants to the poles. This article examines what is happening in the seemingly inhospitable but crowded brine network, including the latest observations on the accumulation of human pollution.