Define eutrophication. Mention any two adverse effects it can cause in a freshwater lake.
Answer
Eutrophication is the enrichment of water bodies with excess nutrients, leading to rapid algal growth. Two adverse effects are (1) depletion of dissolved oxygen causing fish kills, and (2) formation of harmful algal blooms that release toxins.
Step-by-step solution
- State the definition: excess nutrients (mainly N and P) cause rapid growth of algae and aquatic plants.
- Explain that when algae die, their decomposition consumes dissolved oxygen, leading to hypoxic conditions and fish mortality.
- Mention that some algae produce toxins harmful to humans and animals, constituting harmful algal blooms.
- Summarize the two effects as required.
Common mistake: Confusing eutrophication with pollution caused by oil spills; the focus is on nutrient enrichment.
Concept tested: Eutrophication definition and impacts
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