Which of the following human activities is a primary cause of eutrophication in aquatic ecosystems?

• A. Deforestation in tropical rainforests
• B. Burning fossil fuels for energy
• C. Excessive use of fertilizers in agriculture
• D. Overfishing in marine environments

Answer: (C)

Verified step by step guidance

1. Understand the concept of eutrophication: Eutrophication is the process by which water bodies become enriched with nutrients, particularly nitrogen and phosphorus, leading to excessive growth of algae and other aquatic plants. This can result in oxygen depletion and harm aquatic life.
2. Identify the primary sources of nutrients causing eutrophication: Excessive use of fertilizers in agriculture is a major contributor. Fertilizers contain high levels of nitrogen and phosphorus, which can run off into nearby water bodies during rainfall or irrigation.
3. Analyze why other options are less relevant: Deforestation in tropical rainforests, burning fossil fuels, and overfishing do not directly contribute to nutrient enrichment in aquatic ecosystems. These activities may have other environmental impacts but are not primary causes of eutrophication.
4. Connect agricultural practices to eutrophication: When fertilizers are applied excessively, the nutrients they contain can leach into rivers, lakes, and oceans. This nutrient influx promotes algal blooms, which can block sunlight and deplete oxygen levels as algae decompose.
5. Summarize the impact of eutrophication: The excessive nutrient input from fertilizers disrupts aquatic ecosystems, leading to dead zones, loss of biodiversity, and harm to organisms dependent on oxygen-rich environments.