The effect of age and environmental factors on the vertical migration and distribution of Chaoborus flavicans (Meigen) larvae
Notice bibliographique
Résumé
The effect of age and some environmental factors, especially light, on the vertical migration and distribution of Chaoborus flavicans larvae were studied both in the field and in the laboratory at Corbett Lake, British Columbia during the summer of 1963. Distribution and migration of Chaoborus larvae were studied largely by frequent horizontal Clarke-Bumpus plankton tows made at 1 metre intervals from the surface almost to the maximum depth of the lake. Marked differences were noted in daytime vertical distribution and diel migration of 5 size (or age) classes of larvae. These size classes probably corresponded approximately to larval instars. Class 0 and 1 larvae inhabited the epilimnion in the daytime throughout the summer, while class 4 larvae were largely confined to the hypolimnion during the day. Class 2 and 3 larvae occupied the epi-, meta-, and hypolimnion in the daytime during June and July, but were found chiefly in the hypolimnion during August and September. Only the older larvae (class 2, 3 and 4) underwent marked diel vertical migration which consisted of 4 phases: 1) daydepth, 2) ascent from day-depth to the surface, 3) gradual descent from surface, 4) rapid descent during dawn. The ascent occurred when subsurface light was rapidly diminishing at dusk, while the descent took place during darkness and was most marked when light started to penetrate the subsurface layers during dawn. Seasonal changes in timing of ascent and descent appeared to be correlated to seasonal changes in time of disappearance of subsurface light intensity during dusk. The rates of ascent and descent calculated from the analysis of echo traces were 13.6 and 1.1 m/hr respectively. Further analysis of the echo traces revealed that the Chaoborus scattering layer was in contact with the lake basin during daytime and descent, but not during ascent. Results from observations of larval migration in experimental tubes housed in a dark room corroborated those of the field. Class 2 larvae having similar daytime vertical distribution (surface and 5 m) as class 0 and 1 larvae underwent virtually no diel vertical migration in the tubes, while class 2 and 3 larvae taken from the deeper layers (10-14 m) of the lake did. The diel migration consisted of the same 4 phases observed in the field, as well as a "dawn rise" phase which was particularly evident for class 3 larvae. Complete migration cycles were induced by artificially changing the natural light intensity over an experimental tube during the period of relatively constant light (0900-1900 hours); the larvae responded most markedly to changes in light intensity at the 0-1000 lux range. Experiments indicated that the diel vertical migration of Chaoborus larvae is an exogenous rhythm controlled by light.
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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 | 0,001 |
| 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 | 0,000 | 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) | 0,001 | 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 ».