What ecological issue can filamentous algae lead to when they decompose?

When filamentous algae decompose, they can lead to significant ecological issues, primarily oxygen depletion and potential fish kills. This occurs because the decomposition process is biologically demanding. Microorganisms break down the dead algae, consuming oxygen in the water. As the oxygen levels drop, especially in densely populated or poorly mixed waters, aquatic organisms that rely on dissolved oxygen, such as fish and invertebrates, may struggle to survive.

These conditions can create a cascading effect on the aquatic ecosystem. Fish kills can occur when oxygen levels fall below the threshold required for aquatic life, leading to decreased biodiversity and disruption of the food web. Therefore, understanding the impact of filamentous algae and their decomposition is crucial for managing aquatic ecosystems effectively.