Name a major threat to freshwater ecosystems.

Pollution is indeed a major threat to freshwater ecosystems, significantly impacting water quality and aquatic life. Various forms of pollution, such as agricultural runoff, industrial waste, and untreated sewage, introduce harmful substances and nutrients into freshwater bodies. This can lead to issues like eutrophication, where excess nutrients cause algal blooms that deplete oxygen in the water, ultimately harming fish and other aquatic organisms. Furthermore, pollutants can disrupt the delicate balance of freshwater ecosystems, affecting biodiversity and leading to the decline of sensitive species. Protecting freshwater ecosystems from pollution is critical for maintaining their health and the services they provide, such as clean drinking water, habitat for wildlife, and recreational opportunities.