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Polar Mail from April 17, 2009:


Hello Sediment Scientists,

My fifth grade students feel they have a good understanding of why scientists study plants and animals, but are having more difficulty understanding what information you are hoping to gather from the sediment (mud) at the bottom of the ocean. Does it have anything to do with Global Warming?

Bill Klinesteker's 5th grade class
Waylee Elementary School
Portage, Michigan


Dear Bill and class,

The mud on the seafloor is important because it harbors interesting and diverse communities of animals and bacteria. They play important roles in how the ocean operates.

The ocean is very different than the land. For example, in the ocean the plants float. To compare this to land, try to imagine flying plants. To survive, ocean plants - actually, they're called algae - must constantly battle against gravity to stay afloat. The losers sink to the seafloor. There, some are eaten and some decompose.

You can think of the seafloor as the ocean's recycling center. It receives the algae from surface waters. This algae is food for a remarkable zoo of animals that live on and within the sediments. It starts a seafloor food chain that ultimately feeds animals like fish, diving birds, walrus, and gray whales.

In addition, the nutrients that were inside those algal cells are released into the sediment as the algae decompose. Many of the animals that live in the mud create burrows. They keep the water in their burrows clean by flushing them, which they do by wiggling or squirming or by oscillating like pistons. By doing that, they flush nutrients out of the sediment back into the water - and the whole thing starts over, as the nutrients fuel the algae that live in the water.

David Shull, Benthic Ecologist
Western Washington University