Impacts des variations hydrologiques sur les poissons des marais aménagés le long du Saint-Laurent fluvial
Bibliographic record
Abstract
Le but de la presente etude etait de developper des outils permettant d'estimer l'impact des variations hydrologiques du fleuve Saint-Laurent sur les poissons des marais amenages en plaine inondable. Une analyse historique (1960-2002) de l'accessibilite de tous les amenagements depuis le debut de la regularisation du systeme lac Ontario - fleuve Saint-Laurent a ete realisee et la chronologie de la migration et de la reproduction du grand brochet (Esox lucius) et de la perchaude (Perca flavescens) a ete mesuree dans deux marais amenages. De fortes variations interannuelles de la duree d'acces, attribuables aux conditions hydrologiques printanieres, ont ete observees depuis 1960 (1965 : aucun acces; 1973 : 98 ± 38 jours). Une diminution de la duree d'acces aux amenagements, estimee a 1,1 jour/annee, a ete enregistree depuis 1975 (R2 = 0,20; p = 0,01); ce qui pourrait s'etre traduit par une baisse de la diversite et de l'abondance des poissons. Dans les marais ayant fait l'objet d'un echantillonnage, la richesse specifique au sein de la communaute en migration a montre une distribution bimodale qui temoigne du caractere sequentiel du mouvement des differentes especes vers les amenagements. Chez le brochet et la perchaude, les variations journalieres du niveau de l'eau avaient une influence positive sur les prises par unite d'effort (R2 : 0,64 - 0,89; p : 10 °C) doit etre accumule avant que le maximum d'activite de reproduction soit atteint. Cette etude suggere que la duree, la hauteur et la chronologie de la crue printaniere ont un impact sur la richesse specifique, l'abondance des geniteurs et la date de la reproduction des frayeurs hâtifs dans les marais amenages. De nouvelles mesures sur le terrain seront necessaires pour valider les modeles predictifs issus de nos resultats. Les resultats obtenus ont permis de formuler des recommandations preliminaires concernant la gestion des niveaux d'eau du fleuve Saint-Laurent par la Commission mixte internationale. The goal of the present study was to determine the impact of water level fluctuations of the St. Lawrence River on fish populations in the managed marshes. The historical accessibility of all marshes since the beginning of flow regulation in the Lake Ontario - St. Lawrence system was quantified and the migration and reproduction chronology of northern pike (Esox lucius) and yellow perch (Perca flavescens) was determined in two managed marshes. High interannual variations in the duration of the access explained by hydrological conditions in the spring were observed since 1960 (1965 : no access; 1973 : 98 ± 38 days). Since 1975, a decrease of the annual access duration (1.1 day/year; R2 = 0.20; p = 0.01) was registered, which could lead to a decrease of fish diversity and abundance in the marshes. Daily values of species richness in the fish community migrating to the studied marshes showed a bimodal distribution representing differences in the migration sequence of the different species. Pike and perch captures per unit of effort were positively influenced by daily variations of the water level (R2 : 0.64 - 0.89; p 10 °C) had to be accumulated before reaching the maximum spawning time. This study suggests that the duration, the amplitude and the chronology of the spring flood has an impact on the species richness, the abundance of adult fish and the timing of the reproduction in the managed marshes. New field works will be necessary to validate the predictive models in the future, these results will help to improve the regulation of the St. Lawrence water flow by the International Joint Commission.
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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 | 0.001 | 0.002 |
| 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 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 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".