Malacological insights into the marine ecology and changing climate of the late Pleistocene early Holocene Queen Charlotte Islands archipelago, western Canada, and implications for early peoples
Bibliographic record
Abstract
The first intertidal species to colonize the Queen Charlotte Islands archipelago along the northeastern Pacific margin of Canada after the last glacial maximum (LGM) was Macoma nasuta at 13 210 ± 80 14C years BP. Prior to this time, molluscs were likely excluded where grounded ice extended from the 2 km thick Cordilleran ice sheet on mainland British Columbia. Low water temperatures, high sedimentation rates, high turbidity, dilution, and low primary productivity limited invertebrate colonization subsequent to the LGM, a period of rapid sea-level and climate change. As an adult, M. nasuta is a facultative deposit-suspension feeder that tolerates high turbidity and lowered salinity, and its pediveligers and early juveniles must also have been able to survive these conditions. Subsequently, in addition to M. nasuta, Macoma irus (inquinata), Saxidomus giganteus, Protothaca staminea, Protothaca tenerrima, Hiatella pholadis, Clinocardium nuttallii, and Mytilus trossulus constituted a typical intertidal bivalve assemblage. These findings are explained in terms of the physiology, feeding mechanisms, development, and sediment preferences of living molluscs. The disappearance of most bivalve species between ~11 000 and 10 000 14C years BP indicates the onset of a short interval of low sea-surface temperatures coincident with the Younger Dryas cooling event. Some cold-hardy species persisted, including Clinocardium californiense, Mya truncata, and Serripes groenlandicus. Bivalve species not previously reported as Pleistocene fossils were collected in sediments dating older than 10 000 14C years BP. They include Macoma incongrua, Musculus taylori, Mytilimeria nuttallii, and Tellina nuculoides. Fossil assemblages of intertidal molluscs are used to map ancient shorelines and indicate which species were available as a subsistence resource for early peoples from at least 13 210 ± 80 14C years BP. Intertidal food biomass densities may have reached present commercially harvested levels on southern Moresby Island by 8800 ± 70 14C years BP and on northern Graham Island by 8990 ± 50 14C years BP. When early peoples might have been migrating along the littoral zone, the molluscan productivity of the outer coast was much higher than it is at present.
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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 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.002 | 0.002 |
| Science and technology studies | 0.002 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.005 | 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".