Spatial and trophic niches through ontogeny and the influence on native species restoration: Using Lake Ontario Atlantic salmon (Salmo salar) as a model species
Notice bibliographique
Résumé
Species reintroductions are an important aspect of conservation biology to prevent biodiversity loss, and post-release monitoring can help in understanding and improving restoration success. Generally, population sizes are monitored to determine if reintroductions are successful, however, it does not reveal why it is a success or failure. This thesis proposes that by understanding a species ecological niche within the introduced abiotic and biotic habitat throughout its life history, the mechanisms behind restoration success or failure can be better determined, as well as assist management with improving the potential for species restoration. Once extirpated, Atlantic salmon (Salmo salar) have been reintroduced into Lake Ontario, however, numbers of returning adults remain low. Thus, focusing on Lake Ontario Atlantic salmon provided an opportunity to assess restoration potential and improve restoration success. The spatial and trophic niches of Lake Ontario Atlantic salmon were assessed at various life stages. This thesis begins with understanding the seasonal trophic niche of juvenile Atlantic salmon stocked into streams with different fish communities, and specifically to determine if trophic interactions and other species abundances limit restoration success. Stream resident fish communities appeared to partition resources across seasons such that abundant species had low trophic niche overlap with young-of-year Atlantic salmon minimizing overall competition given available resources. The next chapter followed the migration success of Atlantic salmon smolts coming from different rearing environments. Acoustic telemetry revealed that there was similar migratory performance and no impacts from weirs, yet survival was greater in naturally-reared smolts than hatchery-reared smolts. Survival was lowest at the release site indicating pre-migration mortality, and specifically high stocking-related mortality of hatchery-reared smolts. Overall, when either stocked as parrs or smolts there was low mortality during the actual migration. Lastly, this thesis investigated the trophic and spatial niches of adult Atlantic salmon within the lake environment and compared them to the salmonid community. All salmonids primarily consumed alewife and exhibited some overlap in trophic niche due to this prey commonality and similarity in stable isotope values. Spatially, Atlantic salmon are using slightly different habitats than the other salmonids, regardless of consuming similar prey, thus limiting the spatial niche overlap within Lake Ontario. This thesis has increased our understanding of Lake Ontario Atlantic salmon. There were no major ecological niche overlaps with other salmonids, limiting resources, or reduced survival of Atlantic salmon, from juveniles and smolts in the river to adults in the lake. However, this research revealed a few indirect aspects that could affect success and potentially limit restoration (e.g., stocking related survival, thiamine deficiency, spawning success) which could be further researched. Understanding ecological niches can be useful beyond Atlantic salmon restoration in Lake Ontario such as with other reintroduction projects, stocking programs and fisheries management. Researching different aspects of a species ecological niche, like its trophic and spatial niches at various life stages, provides management with information to increase the potential for reintroduction success, such that ultimately, reintroductions may be a more effective tool towards species conservation and increasing biodiversity.
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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 | 0,000 |
| Études des sciences et des technologies | 0,000 | 0,000 |
| 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) | 0,002 | 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 ».