Which of the following is a commonly monitored parameter in water quality assessments?

Dissolved oxygen levels are a critical parameter in water quality assessments because they are essential for the survival of aquatic organisms. The amount of oxygen dissolved in water influences the health of fish and other aquatic life, as they require sufficient oxygen to thrive. Monitoring dissolved oxygen levels helps assess the water's ability to support life, detect pollution, and understand ecosystem dynamics.

While temperature can be an important factor in water quality, it is not the sole parameter that is commonly monitored. The number of fish species and the presence of algae can provide useful information about ecosystem health, but they are often considered secondary indicators and may not reflect immediate water quality issues as directly as dissolved oxygen levels do. Thus, dissolved oxygen remains a primary focus in routine water monitoring efforts.