Question

Write three effects of cultural eutrophication.

Answer 1

1. Algal Blooms: Rapid nitrogen and phosphorus increases cause “blooms” of algae and phytoplankton. These can tint water green, emit bad odours, and release poisons that are toxic to humans and wildlife.
2. Hypoxia (“Dead Zones”): When large numbers of algae die and disintegrate, bacteria eat almost all of the dissolved oxygen in the water. This produces “dead zones” in which fish and other aquatic animals cannot survive.
3. Loss of Biodiversity: The change in water chemistry and light penetration (which is blocked by surface algae) alters the ecosystem balance. Sensitive native species die out, and they are frequently replaced by invasive species or simpler creatures that thrive in low-oxygen conditions.