What role does dissolved oxygen play in aquatic ecosystems?

Dissolved oxygen is crucial in aquatic ecosystems primarily because it supports respiration and decomposition processes. Aquatic organisms, including fish and invertebrates, rely on dissolved oxygen for respiration, which is essential for their survival. When these organisms take in oxygen, they undergo cellular respiration, a process that converts organic materials into energy needed for growth and maintenance.

Additionally, dissolved oxygen plays a significant role in decomposition. Decomposers such as bacteria and fungi also require oxygen to break down organic matter, recycling nutrients back into the ecosystem. This process is vital for maintaining the health and balance of aquatic environments because it ensures that nutrients remain available for primary producers like aquatic plants.

While the other options present different aspects of aquatic ecosystems, they do not accurately reflect the primary role of dissolved oxygen.