Unexpected results from direct measurement, with a torsion microbalance in a closed system, of calcification rates of the coral Agaricia agaricites (Scleractinia:Agariicidae) and concomitant changes in seawater pH
Notice bibliographique
Résumé
"Ocean acidification is impacting the calcification of corals, but the mechanisms of calcification are still unclear. To explore the relationship between calcification and pH, small pieces of coral were suspended from a torsion microbalance in gently stirred, temperature controlled, seawater in a closed chamber. Net calcifica - tion rate and pH were continuously monitored while light, temperature or pH could be manipulated. The coral pieces were from the edges of thin plates of Agaricia agaricites and were studied alive and freshly collected. Unexpectedly, when calcification was taking place (n=9, 0.082 mg.hr -1 .cm -2 ), as determined by weight increase, the pH of the surrounding seawater medium changed little (n=10, -0.0047 pH units.hr -1 .cm -2 ). When calcification was not taking place the decrease of seawater pH was an order of magnitude higher, -0.013 pH units.hr -1 .cm -2 . This is the opposite of what is expected when calcium carbonate (CaCO 3 ) forms. Similarly, fresh skeleton ini - tially showed no change of pH in the seawater medium although the rates of weight gain were high (upto 1.0 mg hr -1 .cm -2 ). After 10 hours, as the rate of deposition decreased following a generalized Michaelis-Menten growth curve, the pH began to decrease dramatically indicating an increase of CO 2 in the seawater. These unexpected results can be explained if unstable calcium bicarbonate (Ca(HCO 3 ) 2 ) is formed in the organic matrix/carbonic anhydrase surface and slowly transforms later to CaCO 3 . Pieces of living coral monitored in the chamber for 30 hours gained weight during the day and loss it at night. The loss would be consistent with the transformation of Ca(HCO 3 ) 2 to CaCO 3 with the release of CO 2 . The mean calcification rate of live coral was greater (n=8, p=0.0027) in high light (120 μmol.s -1 .m -2 ) at 0.098 mg.hr -1 .cm -2 , compared to 0.063 mg.hr -1 .cm -2 in low light (12 μmol.s -1 .m -2 ). However, at the same time the mean rate of pH change was -0.0076 under low light compared to -0.0030 under high light (n=8, p=0.0001). The difference can be explained by CO 2 being used for photosynthesis by zooxanthellae. The deposition rate of live coral was not affected by the addition of phosphate but the rate of weight gain by the freshly collected skeleton was strongly enhanced by phosphate. These results indicate that care should be applied in the application of the alkalinity anomaly technique for the measurement of calcification in corals."
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 distillée sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Apprise à partir de 10 348 étiquettes directes de Codex et de 10 348 étiquettes directes de Gemma. Le mode candidate est l'union des têtes enseignantes seuillées; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont ni des étiquettes humaines ni des étiquettes directes de modèles de pointe.
Scores Codex et Gemma par catégorie
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,002 | 0,000 |
| Méta-épidémiologie (sens strict) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,001 | 0,000 |
| Bibliométrie | 0,000 | 0,001 |
| Études des sciences et des technologies | 0,000 | 0,000 |
| Communication savante | 0,000 | 0,001 |
| Science ouverte | 0,001 | 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 tête enseignante, 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 ».