A trophic cascade refers to the ecological phenomenon where changes in the population of one species, usually a predator, lead to significant impacts on the species at multiple trophic levels. For example, the decrease in a dominant predator can cause overpopulation of herbivores, which in turn affects plant communities and overall biodiversity. Trophic cascades demonstrate the interconnectedness of ecosystems, emphasizing how changes at one level can ripple throughout the entire food web.