In the context of invertebrates—specifically aquatic macroinvertebrate biomonitoring—ASPT stands for
Average Score Per Taxon.
It is a water quality index used to assess the pollution levels of rivers and streams, particularly focusing on organic pollution, by analyzing the sensitivity of invertebrate families found in a sample.
Key Details About ASPT
Calculation: ASPT is calculated by taking the total score of a sample (often from the Biological Monitoring Working Party, or BMWP, system) and dividing it by the total number of scoring families/taxa present.
Purpose: It evaluates the overall "sensitivity" of the community. A high ASPT score indicates a cleaner, less polluted site with many sensitive, high-scoring taxa (like mayflies, stoneflies, and caddisflies).
Range: It generally ranges from 0 to 10 (or 0.0 to 6.0 in some specific systems).
Independence: Unlike the raw BMWP score, the ASPT is largely independent of sample size or the total number of families found, making it a more robust, reliable, and consistent indicator.
Context: ASPT is frequently used in conjunction with WHPT (Whalley, Hawkes, Paisley & Trigg) or BMWP systems to comply with environmental quality regulations, such as the Water Framework Directive (WFD).
In the context of invertebrates,
ASPT stands for Average Score Per Taxon.
It is a widely used biological index used to assess water quality in rivers and lakes based on the presence of benthic macroinvertebrates.
Key Features of ASPT
Calculation: It is calculated by dividing the total Biological Monitoring Working Party (BMWP) score by the number of families (taxa) identified in the sample.
Purpose: It measures the average sensitivity of the invertebrate community to environmental pressures, primarily organic pollution and dissolved oxygen depletion.
Scoring: Each macroinvertebrate family is assigned a score from 1 to 10 based on its tolerance to pollution.
High Scores (e.g., 7.0–10.0): Indicate "clean" or "very good" water quality, often characterized by sensitive species like mayflies and stoneflies.
Low Scores (e.g., 1.0–5.0): Indicate "dirty" or "not good" water quality, dominated by pollution-tolerant species like worms (Oligochaeta).
Reliability: Unlike the raw BMWP score, ASPT is considered more robust because it is less affected by sample size or seasonal variations in species richness.