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How can too much fertilizer runoff harm rivers, lakes, and oceans?
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Biosphere
Earth's environment includes the atmosphere, the hydrosphere, the lithosphere, and the biosphere.
Fertilizer runoff harms aquatic ecosystems through a process known as cultural eutrophication, which accelerates the natural aging of water bodies by introducing excess nitrogen and phosphorus.1
When these nutrients enter rivers, lakes, and oceans, they trigger excessive growth of algae and phytoplankton, creating water blooms. These blooms cause several destructive effects:213
- Oxygen Depletion: As the massive populations of algae and phytoplankton die and decompose, the process consumes vast amounts of dissolved oxygen. This leads to hypoxia—a state of extremely low oxygen—which causes the suffocation and death of fish, crustaceans, and other aquatic life.231
- Dead Zones: In severe cases, these hypoxic conditions create vast "dead zones," such as those found in the Gulf of Mexico, where almost no life can survive.23
- Ecosystem Degradation: Nutrient enrichment can shift ecosystems toward less diverse, algae-dominated states, harm fisheries, and promote toxic blooms that may poison wildlife or threaten human health.13
Protecting these environments is a moral imperative, as the degradation of these habitats threatens global biodiversity and the essential resources upon which many species and human communities depend.13