Spatial and Temporal Sediment Dynamics in a Subarctic Salt Marsh (Gulf of St. Lawrence, Canada)
Bibliographic record
Abstract
Gibeault, C.; Neumeier, U., and Bernatchez, P., 2016. Spatial and temporal sediment dynamics in a subarctic salt marsh (Gulf of St. Lawrence, Canada). Sediment transport in the salt marsh and the lagoon of Penouille is driven by tidal currents, waves, wind, and ice rafting, which interact with topography and vegetation to control the spatial distribution of surface sediments. Multiple linear regressions of 203 samples of marsh surface sediments show that grain size gets finer and organic matter content increases with distance from the lagoon inlet, the sandy peninsula, the closest creek, and the lagoon. The vegetation parameters and surface microtopography have only a minor influence. Locally, grain size can get finer with elevation, while organic matter content increases. However, across the entire marsh, grain size exhibits the opposite trend with elevation, a consequence of aeolian transport and ice rafting. The 94 samples covering the lagoon show a trend of finer grain size with distance from the lagoon inlet and with sea grass cover. Penouille marsh has been relatively stable from 1975 to 2008: analysis of five georeferenced aerial photographs shows that only 3% of the marsh area was lost due to outer marsh edge retreat. Ten sediment cores collected in the marsh show a thickness of 0.14–0.72 m of marsh sediments overlying a sandy substrate. Radiocarbon dates suggest that marsh establishment occurred in the north side of the lagoon around 1000–1200 cal BP. Accretion rates based on radiocarbon dates are 0.4–1 mm/y for several centuries, whereas 137Cs dating indicates rates of 1–3 mm/y since 1963, and accretion plates indicate 2.9 ± 0.9 mm/y between 2010 and 2012. Accretion rates since 1963 are similar to the relative sea-level rise (RSLR) of 1.5 mm/y at Penouille for the 1969–2014 period. However, the accelerated RSLR of 3.7 mm/y observed over the last 20 years and additional RSLR due to climate change may progressively drown the marsh if accretion rate does not substantially increase.
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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 | 0.002 | 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 | 0.001 |
| 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 itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, 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".