Answer :
Final answer:
The statement is true; the death of massive algal blooms leads to oxygen depletion in the water, creating dead zones that negatively affect aquatic animal populations.
Explanation:
The statement is true. Widespread reproduction and subsequent death of algae in a marine setting can have significant effects on the concentration of dissolved oxygen in the water. As the algal population expands and then dies off, it leads to an increase in organic matter that is available to bacteria living in deeper waters. These nonphotosynthetic microorganisms then proliferate, consuming large amounts of oxygen and creating dead zones. In these zones, oxygen levels drop so low that most aquatic animal life cannot survive, leading to decreases in the populations of fauna in affected areas.
Additionally, eutrophication, which is often caused by runoff containing fertilizers, can lead to an excess of nutrients in the water that fosters these harmful algal blooms. As the algae decompose, they cause oxygen depletion (hypoxia), making it difficult for fish and other aquatic organisms to survive. This also affects the marine food web, the interactions between different species, and can contribute to broader ecological imbalances.