The effects of in-stream structure placements on a macroinvertebrate community : testing of reach-scale responses and mechanisms with regard to flow refugia
Notice bibliographique
Résumé
The effects of placements of in-stream structures on a macroinvertebrate community were examined in Spring Creek, a second-order stream of British Columbia, Canada. I tested the responses of organic matter and macroinvertebrates to structural changes at two spatial scales: reach-scale responses to the placements of boulder clusters; and the mechanisms through which in-stream structure affects macroinvertebrates as flow refugia at a microhabitat scale. The reach-scale study was conducted in three sections (length 40-56 m) within a 300-m reach with at least 20 m buffers between them. Two upstream reference sections were in relatively natural condition with channel meanders and abundant woody debris whereas the downstream treatment section had a relatively straight stream channel with less woody debris. In the treatment section, 6 boulder clusters were installed to manipulate habitat heterogeneity. These three sections were studied for three months prior to and 1.2 year following the placements of boulder clusters. Mean (140 %) and coefficient of variation (115 %) of velocity increased in the treatment section whereas the reference section remained relatively unchanged after the treatment. Through the increased organic matter storage (550 %), total macroinvertebrate abundance, which was dominated by detritus feeders, increased (280 %) in the treatment section to become similar in level to that in the reference sections almost one year after that treatment. However, the effect of placements of boulder clusters on taxonomic richness was negligible. Effects of food resource values on macroinvertebrate colonization of flow refugia during floods were examined in the downstream 180-m reach during three floods in 1999 and 2000. Substrate cages were used as an experimental unit, and were assigned to combinations of three types of treatments: food (natural or artificial leaves); flow refugia (reduced velocity or exposed); and flood (retrieval before or after a flood). Low and stable antecedent flow conditions resulted in significant responses of animals to the flood whereas high and variable antecedent flow resulted in little response. During the flood with the highest peak discharge observed among the three trials, two detritivorous taxa Paraleptophlebia and Despaxia accumulated in refugia and their colonization was disproportionally higher in the cage provided with high food resource value (natural leaves). Nevertheless, the accumulation of macroinvertebrates in flow refugia was species-specific, and was not consistent across the community. It was concluded that instream structures (boulder clusters) could be used as a remedy to restore macroinvertebrate community productivity.
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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 | 0,002 |
| 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 | 0,001 |
| Communication savante | 0,001 | 0,000 |
| Science ouverte | 0,001 | 0,001 |
| Intégrité de la recherche | 0,000 | 0,000 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,001 | 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 ».