The sublethal effects of 2,4-D dimethylamine on wood frog tadpoles in Saskatchewan
Notice bibliographique
Résumé
Declining amphibian populations in association with an incidence of deformities have been observed globally. These observations have alarmed the scientific community as well as the general public. Potential causes include exposure to pesticides; therefore two experiments were performed to test the sublethal effects of the herbicide 2,4-dichlorophenoxyacetic acid (2,4-D) on tadpoles of the wood frog (Rana sylvatica). Wood frog tadpoles in the first experiment were exposed to 2,4-D amine at 0.1, 1.0 and 100 ug/L in outdoor microcosms. Morphometric measures (total length, snout-vent length (SVL) and wet weight) were taken at metamorphic climax. Deformities and circulating hormone concentrations (corticosterone - CORT) were also assessed. Results showed that though tadpoles were exposed to various concentrations of 2,4-D throughout their aquatic life, there were no treatment differences associated with any of the endpoints except for total length (p = 0.023). Total length during metamorphosis was highly variable. Although statistically significant, biological significance was questionable. The second experiment was conducted in the field using natural ponds. The experimental groups included forested ponds (removed from pesticide exposure), agricultural ponds (potentially exposed) and treated agricultural ponds (intentionally treated with 2,4-D to achieve a concentration of 10 ug/L). Relatively rapid degradation of 2,4-D occurred in all treated ponds. The mean half-life was 8.0 + 5.5 days. In spite of the degradation, 2,4-D was present in the ponds until tadpoles metamorphosed. Similar endpoints including morphometric measures, as well as deformities and plasma CORT hormone were determined. In addition, total lipid and total protein (of the carcass) were also measured. Unlike the microcosm study, statistically significant differences were observed in SVL, wet weight and total protein although the differences may have been unrelated to 2,4-D exposure. The metamorphs sampled from the forested ponds were smaller in SVL (23% shorter) and wet weight (58% lighter) (p < 0.029) relative to the other two groups. Total protein in the metamorphs from the forested ponds was 22% lower than that of the agricultural ponds (p = 0.020). Reduced hormonal response to acute stress (p = 0.001) was found in metamorphs of the forested ponds compared to those of the other two groups (66% lower response). Herbicide exposure may have induced low level stimulation of growth (a positive impact on the exposed animals), as well as a possible elevation of baseline corticosterone, in the agricultural and treated metamorphs or there may have been a negative stressor present in the forested pond environment. It is not possible to identify the specific factors that were involved. It is unclear if 2,4-D affected the growth and development of wood frog tadpoles.
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 | 0,000 |
| 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 ».