Long-term changes in invertebrate size structure and composition in a boreal headwater lake with a known minnow introduction
Why this work is in the frame
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Bibliographic record
Abstract
To determine the extent and timescale of predation impacts occurring in a historically fishless headwater lake near Sudbury, Canada, we surveyed the larval remains of the invertebrate predator Chaoborus and the pelagic cladoceran Bosmina, within a 210Pb dated lake sediment core. Size measures of fossil Bosmina mucros, carapaces, and antennules provided inferences of predation intensity. We observed two notable shifts of predation over the span of our ~500 year record. First, in the late-1800s, a considerable reduction in Bosmina mucro length (an indication of reduced invertebrate predation) occurred following centuries of stable, but high invertebrate predation intensity. Nearly concurrent with reduced invertebrate predation was a substantial decline in sedimentary-inferred chlorophyll a (a measure of primary production). We hypothesize that turn-of-the century climate warming resulted in a shift in the dominant lake stratification regime at our study site, thus impacting both invertebrate predation intensity and overall primary production. Second, following an observed minnow introduction in the 1980s, the Chaoborus assemblage experienced a minor shift from larger-to smaller-bodied species, and total chaoborid concentrations were generally the lowest and most stable of the record. C. americanus was not extirpated from the lake, despite large growth in the minnow population. Although C. americanus is a reliable indicator of fishless conditions when obligate planktivorous fish are considered, our data suggest that absolute fishless conditions may be difficult to establish with confidence using the presence of C. americanus mandibles alone, as this taxon can co-exist with minnow species that are not solely planktivorous. Our paleolimnological investigation provides temporal insight on predator-prey interactions occurring in small, shallow headwater lakes that have experienced historic shifts in predation due to long-term environmental change as well as a contemporary fish introduction.
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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 | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 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 it