Eutrophication Simulator

Nutrient runoff → algal bloom → oxygen depletion → dead zone

Lake Cross-Section
Controls
10%
20°C
50%
Nutrients
Low
Algae
Low
Dissolved O₂
High
Fish health
Good
Healthy lake. Nutrient levels balanced.
Key Takeaways
🌾 Nutrient runoff triggers the cascade — excess nitrogen and phosphorus from agriculture, sewage, or fertilizer wash into waterways and fuel explosive algal growth that wouldn't occur under natural nutrient levels.
🦠 Decomposition is the oxygen killer — when the algal bloom dies, bacteria decompose the massive organic load, consuming dissolved oxygen faster than it can be replenished. This is biological oxygen demand (BOD).
🐟 Hypoxia creates dead zones — when dissolved oxygen drops below ~2 mg/L, fish and invertebrates suffocate. The Gulf of Mexico dead zone (~15,000 km²) is caused by this exact mechanism, driven by Mississippi River nutrient loading.
🌡️ Warming makes it worse — warmer water holds less dissolved oxygen and accelerates bacterial metabolism, making eutrophication more severe under climate change.
Developed by Dutton Lab @ University of Florida