DP Geography: Environmental Consequences of Agriculture - Free Printable

The image illustrates the process of fertilizer runoff and its impact on a stream or river ecosystem over time. The three panels (A, B, and C) show a sequence of events that depict eutrophication, a common environmental problem caused by nutrient pollution.

Let’s analyze each panel:

---

Panel A (Top):

- Fertilizer Run-off is shown entering the stream.
- The water is clear, and there are fish and aquatic plants present.
- This represents the initial state before significant pollution effects.

> ✔ Stage: Pre-pollution – balanced ecosystem.

---

Panel B (Middle):

- More fertilizer has entered the stream.
- There's an increase in plant growth (algae and aquatic plants).
- Fish are still present but fewer than in Panel A.
- The water appears slightly more green due to algal bloom.

> 🌱 Stage: Eutrophication begins — excess nutrients (like nitrogen and phosphorus) from fertilizer promote rapid growth of algae and aquatic plants.

---

Panel C (Bottom):

- Algae and plant growth have become excessive (algal bloom).
- The water is now dark green and murky.
- Fish are dying or absent.
- The bottom layer shows decomposing organic matter (dead plants), which consumes oxygen.

> 💀 Stage: Oxygen depletion — as the algae die, bacteria decompose them, using up dissolved oxygen. This leads to hypoxia (low oxygen), causing fish kills.

---

Labels:

On the right side, we see letters A, B, C, D, E next to the panels.

But only three panels are shown (A, B, C). So likely:
- A = Initial condition
- B = Algal bloom phase
- C = Oxygen depletion and dead zone

However, D and E are not labeled with any panel. Possibly they are meant to be options for labeling the stages.

Assuming the question is asking us to identify the correct order of ecological changes due to fertilizer runoff, the sequence is:

1. Fertilizer enters water → increased plant growth → algal bloom → oxygen depletion → fish death

So the correct sequence is:

👉 A → B → C

---

✔ Final Answer:

The process shown is eutrophication due to fertilizer runoff. The correct sequence of events is:

A → B → C

Where:
- A: Normal conditions with healthy fish and plants.
- B: Algal bloom due to nutrient enrichment.
- C: Oxygen depletion and fish die-off due to decomposition.

This demonstrates how agricultural runoff can harm aquatic ecosystems.

---

If you were asked to label the stages, the correct answer would be:

- A: Before runoff (normal)
- B: After runoff – algal bloom
- C: After decomposition – low oxygen, dead fish

Thus, the progression is A → B → C.

Let me know if you need help interpreting what D and E represent!