Freshwater ecosystems can be as small as a puddle or as large as a raging river. Ponds, lakes and streams occur on every continent, and are home to a host of fish, algae and other water organisms. In Freshwater Ecosystems, students will explore these fascinating and diverse habitats and learn about the biotic and abiotic factors that make up these ecosystems. A hands-on experiment shows students how to test the amount of dissolved oxygen in two different bodies of water, while a visit with a freshwater naturalist examines the importance of wetlands around the world.