Wind‐driven thermocline movements affect the colonisation and growth of <i>Achnanthidium minutissimum</i>, a ubiquitous benthic diatom in lakes
Notice bibliographique
Résumé
Summary Benthic algae form a major component of primary production in shallow waters and are an important component of lake food webs. I tested the effects of thermocline movements and bathymetric slope on the colonisation and population development of a ubiquitous and often dominant benthic diatom, Achnanthidium minutissimum . Sampling sites were positioned along the upwind and downwind shorelines of an elongated 22 km 2 lake basin, on a range of bathymetric slopes (1–16%). A first set of substrates was deployed at eight sites during early stratification (June 19, 2004) and were sampled after 4, 11 and 20 days and 5.5 and 11 weeks to compare colonisation, establishment, early growth rate and density of mature populations. The second set of substrates was deployed at 16 sites in mid‐summer (July 26) and was sampled after 5.5 weeks. The density of A. minutissimum and their average cell length were measured in all samples. Thermocline movements were calculated using a 3D hydrodynamic model, which was calibrated offshore in the lake basin and validated at each sampling site. Achnanthidium colonised the open substrates very rapidly. Initial cell densities increased with increasing thermocline movement, especially along shallow bathymetric slopes. These results suggest an inverse relationship between thermocline‐induced nearshore turbulence and bathymetric slope. The density of early colonisers was reduced by 30–95% during the establishment period (4–11 days after substrate deployment), suggesting that Achnanthidium needs time to attach firmly to the substrate and is vulnerable to disturbances during that period. Achnanthidium established most efficiently at upwind nearshore sites exposed to more thermocline movement. The early growth rate of Achnanthidium in nearshore areas was negatively related to mean water temperature, a likely surrogate for nutrient availability at the sediment–water interface. The density of Achnanthidium in mature populations was positively related to thermocline movements and showed a negative interaction with bathymetric slope early in the stratification period, but not later in summer. These results suggest that physical forces associated with thermocline movements interact differently with the bottom in nearshore areas as the season progresses and as the water‐column stabilises. The size of Achnanthidium cells increased during settlement and early population growth, peaked in early July at most sites and decreased over the rest of the summer. This common pattern of seasonal change in Achnanthidium cell sizes suggests a strong factor synchronising its life cycle across the whole lake basin. Thermocline movements over nearshore substrates clearly affect the colonisation and population development of A. minutissimum . These results support the idea that wind‐driven physical forces are a major factor structuring nearshore habitats in lakes, even in the lower littoral zone, and that benthic organisms should distribute themselves in a predictable way around lake basins.
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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 | 0,000 | 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) | 0,000 | 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 ».