Nature creates its own density column in marine systems, which is extremely important for the triggering of the spring bloom of phytoplankton. Phytoplankton are an important food source for all organisms- from microscopic zooplankton to large marine mammals such as walrus and whales. The different salinities (and therefore, different densities) of water help to stabilize the water column (by limiting
Polar Bears International is a nonprofit organization dedicated to the worldwide conservation of the polar bear and its habitat through research and education. They provide scientific resources and information on polar bears and their habitat to all interested parties. There is a tools for teachers and students section complete with lesson plans, a board game, maps, and related links.