Assessing the causal relationships of ecological integrity: a re‐evaluation of Karr's iconic Index of Biotic Integrity
Bibliographic record
Abstract
Abstract The Index of Biotic Integrity (IBI) has been widely used since the 1980s to estimate ecological integrity—the capacity of an ecosystem to support and maintain its full range of components and processes. Despite this, IBI approaches have been criticized for their lack of objectivity, of justification for the selection of metrics, and of statistical rigor. In this paper, we assessed the potential of canonical correspondence analysis (CCA) and Structural equation modeling (SEM) as complementary methods for assessing ecological integrity. We use an iconic freshwater ecosystem dataset from Northeastern Illinois to assess ecological integrity using both classical IBI approach, and compare this with alternative methods. When we attempt to replicate the IBI methodology, we find issues with the approach including the possibility of the same IBI value for many possible levels of ecological integrity. We showed with the use of other methods (CCA) that the use of tolerant species, total abundance, and total richness—all defining components in IBI—can result in misleading interpretations of ecological integrity and that IBI scores might not comprehensively depict integrity scenarios. Structural equation modeling allowed us to test a conceptual causal model of ecological integrity. We found that water quality had an effect on the diversity and abundance of fish, and these in turn had an effect on trophic function, revealing important relationships between variables that contribute to ecological integrity. We conclude that CCA and SEM can complement multimetric indices, like IBI, and help with the development of more reliable, objective, and science‐based estimations of ecosystem integrity, as well as generate testable hypotheses about ecological integrity.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.016 | 0.039 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.006 | 0.005 |
| Science and technology studies | 0.001 | 0.002 |
| Scholarly communication | 0.003 | 0.002 |
| Open science | 0.001 | 0.002 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".