GEF

Unit 2  |  Water Science and the Water Cycle 53 Many freshwater ecosystems are also vulnerable to trophic cascades , in which the introduction or removal of one species has profound effects on the entire ecosystem. A good exam- ple is from the Eel River in Northern California. In this case, removal of steelhead trout and other large fish species left spe- cies that the large fish preyed upon to feast on the species that fed on algae. Without enough species to feed on the algae, the result was destructive algal blooms. A better understanding of ecosystems and ecosystem functions allows us to prevent these types of disruptions in the future. TROPHIC CASCADES Systemic changes in an ecosystem resulting from a disruption such as the removal of a top predator. WATCH & LEARN http://bit.ly/2uAtBHF Watch the video and respond to the questions below. 1. Name three examples of aquatic ecosystems. 2. Name three services that aquatic ecosystems offer to humans. 3. What are some human activities putting aquatic ecosystems in danger? video: Aquatic Ecosystems