Mapping seabed assemblages using comparative top-down and bottom-up classification approaches
Bibliographic record
Abstract
Acoustic technologies yield many benefits for mapping the physical structure of seabed environments but are not ideally suited to classifying associated biological assemblages. We tested this assumption using benthic infauna data collected off the south coast of England by applying top-down (supervised) and bottom-up (unsupervised) classification approaches. The top-down approach was based on an a priori acoustic classification of the seabed followed by characterization of the acoustic regions using ground-truth biological samples. By contrast, measures of similarity between the ground-truth infaunal community data formed the basis of the bottom-up approach to assemblage classification. For both approaches, individual assemblages were mapped by first computing Bayesian conditional probabilities for ground-truth stations to estimate the probability of each station belonging to an assemblage. Assemblage distributions were then interpolated over a regular grid and characterized using an indicator value index. While the two methods of classification yielded assemblages and output maps that were broadly comparable, the bottom-up approach arrived at a slightly better defined set of biological assemblages. This suggests that acoustically derived seabed data are not ideally suited to class ifying biological assemblages over unconsolidated sediments, despite offering considerable advantages in providing rapid and low-cost assessments of seabed physical structure.
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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 | 0.002 | 0.005 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.003 | 0.002 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.002 | 0.001 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.000 | 0.000 |
| 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".