Question

Explain the cause of algal bloom in a water body. How does it affect an ecosystem?

Answer 1

Cause:

Sudden increase in nutrients (nitrates and phosphates) from fertilizers, sewage, and industrial waste leads to excessive growth of algae (algal bloom) — a process called eutrophication.

Effect on ecosystem:

1. Dense algal cover blocks sunlight. 
2. When algae die, decomposition by bacteria consumes most dissolved oxygen. 
3. Low DO causes death of fish and other aquatic organisms. 
4. Algal blooms also release toxins inhibiting growth of other aquatic life. 
5. Results in loss of species diversity and degraded water quality.