Bioassessment monitoring is an assessment of the number and diversity of benthic macroinvertebrates in a water body.

• A. The number and diversity of benthic macroinvertebrates in a water body
• B. Dissolved oxygen levels
• C. pH levels
• D. Turbidity

Answer: (A)

Bioassessment monitoring uses biological indicators to judge water quality, focusing on the community of organisms living in the water. Benthic macroinvertebrates are ideal for this because they are relatively sedentary and integrate conditions over time, so their presence, absence, and diversity reflect long-term ecological health. A healthy system supports a larger, more diverse assemblage, including groups that are sensitive to pollution, while degraded waters tend to have fewer species and be dominated by tolerant taxa. The other options describe abiotic water quality measurements (dissolved oxygen, pH, turbidity), which are important context but do not capture the biological condition that bioassessment specifically measures.