The role of bioaccumulation in ecosystems is to highlight the accumulation of pollutants in organisms over time. When an organism absorbs harmful substances, such as heavy metals or pesticides, faster than it can eliminate them, these toxins build up in its tissues. As one moves up the food chain, these substances become more concentrated in predators, potentially leading to toxic effects. Bioaccumulation demonstrates the interconnectedness of organisms and emphasizes the need for sustainable environmental practices.