Variation in the population dynamics of the invasive bryozoan Membranipora membranacea along a 450-km latitudinal gradient in Newfoundland and Labrador, Canada
Bibliographic record
Abstract
The overall objective of this study was to quantify and compare seasonal (June to November) and inter-annual (2008 and 2009) variation in settlement, recruitment, and colony cover of the invasive bryozoan Membranipora membranacea on the kelp Saccharina longicruris across eight sites spanning a 450-km latitudinal gradient between the southwestern tip of Newfoundland and southeastern tip of Labrador. Thermal histories were calculated for each site to determine the extent that the observed variation was explained by sea temperature. Analysis of settlement data (Chapter II) indicated that (1) settler abundance varied both seasonally and annually with a sharp increase between August and September at warmer sites, and spatially with differences of up to three orders of magnitude between sites, (2) settler abundance and sea temperature were strongly correlated (r(2)=0.577), with maxima at mid-latitudes and minima at the northernmost and southernmost sites, and (3) exposure to waves, degree of kelp blade corrugations, and surface area of colonies of M. membranacea on kelp had little explanatory power on settler abundance across the study sites compared to sea temperature. Analysis of recruitment and colony cover data (Chapter III) indicated that (4) recruitment and colony cover varied seasonally, though variation generally decreased with increasing latitude, (5) temperature in the 76 days preceding measurements explained most [>60%] of the variation in recruitment within each month from late summer [September] to late fall [November] with the highest predictive capability (97%) in late fall, and (6) colony cover was strongly correlated (r(2)=0.524) to recruit abundance from late summer to late fall. Consistently low abundances of settlers, recruits, and colonies at the two northernmost sites suggested that M. membranacea is nearing its northern distribution limit in the northwest Atlantic. This study provides the first quantitative analysis of spatial and temporal variation in the abundance of M. membranacea in Newfoundland and Labrador since its introduction in the early 2000s. It strongly supports the general hypothesis that temperature is a key factor in regulating the population dynamics of this species, while suggesting that oceanographic phenomena such as upwelling and downwelling, which act on larval transport, also affect the dynamics at different spatial and temporal scales. A few inconsistencies both within the system studied and between the system studied and that of Nova Scotia indicate additional long-term observational and experimental studies are required to elucidate factors that regulate local and regional variation in the abundance of M. membranacea in cold temperate and subarctic environments.
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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 | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 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".