Suspended Sediment in Silvester Creek and its Potential Effects on the Westslope Cutthroat Trout Population
Notice bibliographique
Résumé
Total suspended sediment (TSS) can have extensive negative effects on fishes within streams, ranging from mild avoidance by individuals to complete mortality of populations. Severity of effects depends on the concentration and duration of exposure, and the life-history stage of the fish, with eggs and larvae being the most sensitive. I surveyed spring suspended sediment concentrations and duration in Silvester Creek, a small tributary of the Elbow River in the Rocky Mountain foothills of Alberta, to evaluate potential effects of TSS on a rare genetically- pure, apparently native population of westslope cutthroat trout, a spring-spawning species recognized by the federal Species at Risk Act and provincial regulations under the Wildlife Actas Threatened in the province. The Silvester Creek basin lies entirely within a land-use zone permitting effectively uncontrolled use by recreational off-highway vehicles (OHVs) in combination with livestock grazing, logging, and gasfield development. Linear disturbance density is 2.5 km/km2 overall, and reaches 4.8 km/km2 in some parts of the basin, delivering fine sediment at 41 points, including 2 natural sources, from the extreme headwaters to near the mouth. Three sampling regimes were used: an intensive, day-long analysis at 4 principal stations in a long meadow reach; a before-after-thunderstorm analysis at 12 sites; and daily sampling at 5 sites on 6 consecutive days that incorporated a weekend, weekdays, dry weather and rainy days. Control samples from sites above the influence of roads and trails within the Silvester Creek basin were low in TSS, not exceeding 1.2 mg/L, and usually equalling or approaching zero mg/L. In contrast, TSS concentrations downstream from known or expected sediment sources were elevated relative to the controls, commonly averaging 20-40 mg/L during prolonged rainy weather, while individual samples sometimes were much higher (up to 154 mg/L) after an intense thunderstorm, or 179 mg/L after one or more dry-weather OHV crossings. During dry weather TSS remained as low as 5-7 mg/L at 2 stations, but averaged around 20-30 mg/L at 2 others. Durations were sufficient, even for the lowest dry-weather TSS loads, to cause mostly minor to moderate sublethal effects to juvenile and adult trout, but paralethal to lethal effects on eggs and larvae during the ongoing spawning and egg incubation period. Considering the survey results as a reasonable sample applying to typical spring periods in this basin, I estimated that eggs and larvae typically would sustain at least 40-60% mortality from prolonged TSS exposure, and that adult trout typically would experience moderate physiological stress, while juveniles would typically suffer major physiological stress, reduced feeding rate and success, as well as poor condition. After considering previously-reported population data and literature on the requirements of conserving small populations, I concluded that the Silvester Creek population of westslope cutthroat trout is at unnecessary risk due to the effects of prolonged exposure to TSS from the extensive network of linear disturbances in the basin. To adequately protect this rare genetically-pure stock of a designated Threatened species, large parts of the extensive network of roads, trails, cutlines and pipelines connected to the drainage system need to be removed from the basin or disconnected from the stream network, and the landscape restored.
Récupéré en direct depuis OpenAlex et désinversé. Les résumés ne sont pas conservés dans cette base de données : les index inversés représentent 8,6 Go des 9,3 Go de texte de la base, et le serveur dispose de 13 Go libres.
Comment cette classification a été obtenuedéplier
Prédiction machine sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Le volet Gemma est une étiquette directe du modèle pour chaque travail de la base, lue sur la notice réduite au titre. Le volet Codex est un classifieur appris des 10 348 étiquettes directes de Codex et calibré sur les taux pondérés de l'échantillon; les champs sans appui suffisant ne portent aucun appel Codex. Le mode candidate est l'union des deux volets; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont pas des étiquettes humaines.
Scores du classifieur distillé par catégorie (deux têtes)
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,000 | 0,000 |
| Méta-épidémiologie (sens strict) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,000 | 0,000 |
| Bibliométrie | 0,000 | 0,001 |
| Études des sciences et des technologies | 0,001 | 0,001 |
| Communication savante | 0,001 | 0,000 |
| Science ouverte | 0,000 | 0,000 |
| Intégrité de la recherche | 0,000 | 0,000 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,000 | 0,000 |
Scores machine (provisoires)
Les deux têtes enseignantes du modèle étudiant, lues sur ce travail. Un score ordonne la base pour la relecture; il n'affirme jamais une catégorie, et le statut de validation accompagne chaque rangée tel quel.
Scores de référence d'un modèle non mature (critères de maturité non atteints, 7 itérations). Un score ordonne; il n'affirme jamais une catégorie.
score_only:v0-immature-baseline · tel quel depuis la passe de notation : score_only signifie que le nombre peut ordonner les travaux, et qu'aucune étiquette de catégorie n'en découleClassification
machine, non validéePrédiction automatique; un appel candidat d’une seule source (Gemma direct ou Codex distillé), pas un consensus.
Le détail, modèle par modèle et score par score, se trouve en fin de page sous « Comment cette classification a été obtenue ».