"in dead zones resulting from eutrophication, animal life is absent due to the lack of "

In dead zones resulting from eutrophication, animal life is absent due to the lack of oxygen

Explanation:

The eutrophication is a process of enrichment of a water body by minerals and nutrient due to excessive growth of algae. Contamination of a water body with organic nutrients increases the biological oxygen demand and the chemical oxygen demand of the body.

This is because of the growth of a large amount of microbes including the algae in the water body that results in the reduction of oxygen in the particular water body marking a dead zone.