The ecosystem and food web of the Antarctic Peninsula

To view a printable version of this page, click here.

People spend lifetimes in study of the Antarctic Peninsula and its ecosystem. In fact, the United States funds a project called the Palmer Long-term Ecological Research (LTER) Project. The Palmer LTER centers its research on this basic question: "How does the changing sea ice affect the structure and function of the Antarctic Marine Ecosystem?" Scientists break this large question into many smaller questions. These smaller questions can then be tested with experiments or studies of plants and animals in the ecosystem. There is still much to be learned, but here is a basic description of this complex ecosystem:

The Antarctic Marine Ecosystem (the Antarctic Peninsula and its coastal waters) is a region that is known for two very important things:

1. Each year, the sea ice melts and then builds up again as the seasons change.
   
   
2. This region has a large amount of plant and animal life. This life is affected by the changes in the sea ice.

When the sea ice builds up during the Antarctic winter, bacteria, algae and other organisms grow on the surfaces of the sea ice and in cracks within it. This ice community is known as SIMCO (Sea Ice Microbial Community). Krill eat this ice algae.

When the Antarctic spring begins, microscopic plants — phytoplankton — bloom and grow in great numbers. This happens because phytoplankton manufacture their own food through photosynthesis. They use the sun’s energy and their own chlorophyll to process the nutrients in the water. When the days get longer in the spring, more sunlight is available to fuel phytoplankton growth. Phytoplankton abundance can increase rapidly.

Phytoplantkon are eaten by zooplankton. These are small animals that drift in the water, such as copepods and krill. Krill are one of the most important food sources for animals in this region. These animals are eaten, in turn, by squid, fish, seals, penguins, other birds, and whales.

The food web becomes complicated because many animals eat more than one kind of food. Some birds eat other birds or their eggs, some whales eat seals, some seals eat penguins, and some seals eat fish. In some cases, humans harvest some of these animals. There is a treaty that prohibits harvesting animals in these waters, however.

There are other important processes within the food web. As plants and animals die, they decompose. Bacteria aid in this decomposition process, recycling material from living tissue back to nutrients in the ocean. Plankton then use these nutrients to grow, and the cycle continues.

Previous page: Persistent Organic Pollutants
Next page: Project Hypothesis

Photos of gentoo and chinstrap penguins (top of page) and the baby elephant seal (above) are courtesy of Heidi Geisz. Image of phytoplankton (above) courtesy of Karen Baker. Photo of krill (above) courtesy of foto kils.