Polar Ecosystems

Polar Ecosystems

The Arctic and Antarctic regions are both characterized by:
  • ice and snow,
  • year-round cold temperatures, and
  • drastic changes in photoperiod that prevent photosynthesis during a large part of the year.
However, there are fundamental differences that make the two polar regions very different both physically and biologically. We have a better understanding of shallow-water Antarctic ecosystems than we have of the Arctic ecosystems.

Antarctic Region

The Antarctic marine ecosystem lies in the circumpolar Southern Ocean surrounding the central continent of Antarctica. There is no inflow from rivers or sediment but nutrient rich water rises to the surface and fertilizes the Antarctic surface waters. The Antarctic fauna is far richer than the Arctic and has a high degree of endemism and biomass. Antarctic benthic communities usually have several dominant species. The fish fauna is mostly endemic and adapted to below-freezing water temperatures. The bird communities are similar at a given latitude in all parts of the Southern Ocean basin.

Photo shows South Shetland Islands, Antarctic Peninsula. Adelie and Chinstrap penguins.

Arctic Region

By contrast, the Arctic Ocean system is an isolated sea, permanently covered by ice in the center, and surrounded by landmasses. These have several large rivers that discharge sediment into the basin resulting in a substrate of particulate matter and a low-saline stratified surface layer. The Arctic fauna is impoverished and derives from the Atlantic Ocean. Arctic benthic communities are often dominated by one or only a few species. The fish fauna is generalized. There are strong differences between the bird communities at similar latitudes in different parts of the ocean basin.

Polar bears, Ursus maritimus, typically only eat the fat of their kill. From Polar Bears at Risk. Reproduced with permission from WWF 2002 WWF-Norway. All rights reserved.

Based on Nybakken, James W. 2000 Marine Biology. An Ecological Approach. 5th Ed. Benjamin Cummings, San Francisco. 516 pp (see Related Knowledge for more details)

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