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Diagnostic Capability
The diagnostic capacity of bioassessment data and results depends on the development of patterns and response signatures from a database that includes a variety of stressors and the full gradient of human disturbance and biological response. This increases the value of biological data beyond the determination of status (attainment/non-attainment) to include inferences and decisions about causal associations and elimination of candidate causes in a stressor identification process. As natural and human environment relationships can vary from region to region, it is important that environment-biota relationships be established prior to the initiation of any bioassessment program (Yates and Bailey 2010). The development and use of a diagnostic capability is only possible within programs that have specifically developed methods and for which precision and accuracy issues have been addressed.
Some Frequently Asked Questions
Question: What is required to use biological information as a basis for
diagnosing problems?
Answer:
Appropriately detailed biological information is needed to discriminate between
different categories of stressors; however, it requires underlying analyses
of large datasets to reveal patterns of biological response. Tolerances of
individual taxa within a family can differ; thus, diagnosis of biological
impairment will rely heavily on genus level taxonomy. Family level tolerance
values should be used with caution because they are a non-weighted average
of a potentially wide range of tolerances (See Figure). The overall performance
of weighted averaging models to develop tolerance values consistently showed
that genus-level taxonomy had better precision and performance in predicting
environmental conditions in streams.
References
Yates, A.G. and R.C. Bailey. 2010. Covarying patterns of macroinvertebrate and fish assemblages along natural and human activity gradients: implications for bioassessment. Hyrobiologia 637(1):87-100.
Learn more about diagnostic capability:
- Causal Analysis/Diagnosis Decision Information System (CADDIS)
- Biological Response Signatures
- Understanding Biological Responses by Karr and Chu (1997)
- Mulitvariate Statistical Analysis by Karr and Chu (1997)
- Development and Application of Multimetric Indexes in Developing Biological Indicators: Lessons Learned from Mid-Atlantic Streams
- Linking Human Disturbance To Biological Change in Developing Biological Indicators: Lessons Learned from Mid-Atlantic Streams
- The Stressor Identification Process module from the 2003 National Biocriteria Workshop
- Using Bioassessments and Biocriteria to Identify Impaired Waters and Causes of Impairment - Case Study