Using Seasonal Variation in Otolith Microchemical Composition to Indicate Largemouth Bass and Southern Flounder Residency Patterns across an Estuarine Salinity Gradient
Bibliographic record
Abstract
Abstract Estuaries are transitional zones where salinity largely controls the distribution of both freshwater and marine species. However, the degree to which freshwater and marine species use these variable habitats as year-round residents or transient migrants is largely unknown. We used otolith strontium: calcium ratios (Sr: Ca) as a marker for salinity exposure to reconstruct lifetime salinity exposure plots for individual Largemouth Bass Micropterus salmoides and Southern Flounder Paralichthys lethostigma collected across a seasonally variable estuarine salinity gradient. Initially, we determined that a definable relationship existed between salinity, water chemistry, and otolith Sr: Ca for both species. We then used otolith Sr: Ca profiles to indicate lifetime salinity exposure and subsequently classified each fish as either a freshwater resident, transient (combination of freshwater and estuarine signals in otolith), or estuarine resident. For Southern Flounder we also used Sr: Ca profiles from the otolith core to classify each individual as having either a freshwater core or estuarine or marine core. For Largemouth Bass, most (88%) individuals in the lower estuary were estuarine residents, whereas most (77%) individuals in the upper estuary were freshwater residents. These data support the hypothesis that adult Largemouth Bass in lower portions of the estuary do not migrate to avoid salinity, but rather remain in lower portions of the estuary throughout life. For Southern Flounder, 45% of individuals had estuarine or marine core Sr: Ca signals, while 55% had freshwater Sr: Ca core signals. Combining core and residency classification patterns revealed that three patterns described 95% of the Southern Flounder collected: (1) freshwater core and freshwater resident (16%), (2) freshwater core and estuarine resident (37%), and (3) estuarine or marine core and estuarine resident (42%). These data demonstrate that both tidal freshwater and low-salinity estuarine habitats are important nursery areas for Southern Flounder.
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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 | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 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) | 0.001 | 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".