Ocean deoxygenation linked to ancient mesopelagic fish decline
Bibliographic record
Abstract
Abstract Mesopelagic fish are integral to ocean food webs and play an important role in carbon transport through their vertical migration behavior. Ocean deoxygenation caused by anthropogenic warming is expected to pose severe threats to mesopelagic fauna by enhancing physical stress and changing predator-prey relationships. In agreement with this expectation, our fish otolith record in a Mediterranean sediment core shows near absence of mesopelagic species during Sapropel deposition between ~7 and ~10 thousand years ago, concurrent with high surface productivity and low oxygenation of mid-depth waters. Instead, the otolith record is dominated by fish species adapted to epipelagic habitats, including European anchovy ( Engraulis encrasicolus ) and silvery lightfish ( Maurolicus muelleri ). Subsequent reoxygenation starting ~7 thousand years ago is accompanied by a three-fold increase in total otolith abundance. The large majority of these are mesopelagic lanternfish (Myctophidae) that dominate the otolith assemblage from the middle-Holocene to the present. Our findings corroborate expectations that future expansion of midwater deoxygenation could severely deplete mesopelagic fish communities over the coming centuries, with major impacts on marine fisheries, marine conservation, ocean food web structure, carbon storage and other marine ecosystem services.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.004 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.007 | 0.001 |
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; both teacher heads agree on what is shown here.
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".