Some of the larger rivers in Canada include the St. Lawrence, Mackenzie, Fraser, Athabasca, North and South Saskatchewan, and Saint John rivers. The tidal areas where saltwater and fresh water meet are called estuaries . These productive ecosystems, found on Canada's coasts, contain unique assemblages of organisms, including starfish and sea anemones. Energy from the sun is the driving force of an ecosystem. The chemical energy is then used by the plants to perform a variety of functions including the production of plant parts such as leaves, stems, and flowers.
Animals are incapable of photosynthesis.
They therefore eat either plants, other animals, or dead tissue to obtain their energy and required nutrients. In ecosystems, the transfer of energy and nutrients from plants to animals occurs along pathways called food chains . Plant-eating organisms, known as primary consumers , are the next link in the food chain. Decomposers such as bacteria and fungi make up the final link in the food chain. They break down dead tissues and cells, providing nutrients for a new generation of producers.