The excessive growth of plants and fish kills in the lake are due to eutrophication, a process triggered by the runoff of fertilizers into the waterbody. The fertilizers, rich in nutrients like nitrates and phosphates, provide a surge of nutrients for aquatic plants, leading to an overgrowth of algae and other plants. This overgrowth can deplete dissolved oxygen in the water, making it difficult for fish and other aquatic life to survive.
Here’s a more detailed explanation:
Fertilizer Runoff:
When farmers use fertilizers on their crops, excess nutrients from those fertilizers can wash into nearby water bodies like the lake through rainfall and irrigation.
Eutrophication:
The increased nutrients, particularly nitrates and phosphates, trigger a rapid increase in the growth of aquatic plants and algae, especially on the water’s surface. This is called eutrophication.
Oxygen Depletion:
As the algae and plants grow, they consume large amounts of dissolved oxygen in the water during the day for photosynthesis. During the night, they respire and consume oxygen, further reducing its levels. Additionally, when these plants die and decompose, bacteria use up even more oxygen in the process.
Fish Kills:
With the oxygen levels dropping below a critical threshold (usually below 6 ppm), fish and other aquatic animals struggle to breathe and can die. This can lead to mass fish kills, especially in shallower water bodies where sunlight penetration is high, supporting more plant growth.