Over-fertilization can lead to which ecological problem?

Over-fertilization contributes significantly to eutrophication, an ecological problem where nutrient runoff, typically from fertilizers, enters water bodies. When excessive nutrients, particularly nitrogen and phosphorus, accumulate in aquatic ecosystems, they stimulate the rapid growth of algae, known as algal blooms. These blooms can severely deplete oxygen in the water as the algae die and decompose, leading to hypoxic (low-oxygen) conditions that adversely affect aquatic life, including fish and invertebrates.

Eutrophication can also disrupt the balance of aquatic ecosystems, impact water quality, and reduce biodiversity. This process emphasizes the critical link between agricultural practices and aquatic health, showcasing the broader implications of nutrient management in ecosystem sustainability. In contrast, while the other options present serious ecological issues, they are not directly associated with the impacts of over-fertilization.