Home
Back
Biotic Index Equation:
| From: | To: |
The Biotic Index is a water quality indicator that uses the presence and abundance of aquatic organisms to assess the health of freshwater ecosystems. It provides a quantitative measure of water pollution based on the tolerance values of different species.
The calculator uses the Biotic Index equation:
Where:
Explanation: The equation calculates a weighted average of tolerance values, where species with higher pollution tolerance contribute more to the final index score.
Details: The Biotic Index is crucial for environmental monitoring as it provides a direct measure of water quality based on biological indicators. It helps assess the impact of pollution on aquatic ecosystems and track changes over time.
Tips: Enter the total number of individuals collected, specify the number of species, then provide the count and tolerance value for each species. All values must be valid (non-negative numbers).
Q1: What do different Biotic Index scores indicate?
A: Lower scores (0-3.5) indicate excellent water quality, moderate scores (4.0-6.5) indicate fair quality, and higher scores (7.0-10.0) indicate poor water quality with high pollution levels.
Q2: How are tolerance values determined?
A: Tolerance values are assigned based on scientific research that correlates species presence with specific pollution levels. Each species has a predetermined tolerance value (typically 0-10).
Q3: What types of organisms are typically used?
A: Benthic macroinvertebrates are most commonly used as they are sensitive to pollution, relatively sedentary, and easy to collect and identify.
Q4: When is the best time to sample for biotic index?
A: Spring and fall are ideal sampling periods when water levels are stable and aquatic organisms are most active and diverse.
Q5: Are there limitations to this method?
A: The method requires proper species identification and may be less accurate in extremely polluted or pristine waters where few species survive.