Occurrence and seasonal dynamics of metalimnetic Deep Chlorophyll Maximum (DCM) in a stratified meromictic tropical lake and its implications for zooplankton community distribution
Bibliographic record
Abstract
Deep Chlorophyll Maxima (DCM) is an important feature of stratified lakes and oceans but very little is known about the phenomenon in tropical systems. Proximate factors accounting for DCM presence include light, thermal stratification and nutrients but biotic interactions such as zooplankton grazing can actively support DCM formation, structure and maintenance. We examined DCM characteristics in tropical Lake Bosumtwi at biweekly intervals between April and July of 2005 and 2006 and also assessed zooplankton herbivore interactions with the DCM. The onset and development of the seasonal DCM peak was based on stable water column, steep thermocline, availability of a nutricline and nutrient limitation in the epilimnion. Euphotic depth doubled during DCM formation and increasing transparency tripled DCM Chl a in the metalimnion just below the oxycline. DCM, however, disaggregated with seasonally induced deeper mixing. The range of variability in surface chlorophyll did not differ significantly between seasonal and aseasonal DCM period. There was about one‐fourth difference between mean surface and metalimnetic chlorophyll concentrations but this shift in resource location did not trigger a descent to deeper waters by herbivores. Herbivore grazing could not be linked to surface variations in water clarity and deep‐water irradiance needed for DCM formation and maintenance. DCM presence therefore was not enhanced by surface water grazing activities of zooplankton. This suppressed biotic influence indicated that DCM dynamics is driven by lake clarity, thermal and nutrient gradients which constitute key abiotic drivers. Direct consumption of the DCM by herbivorous zooplankton was not evident and the energy therein is possibly lost to the anoxic deep waters of the lake through sedimentation. The sinking organic matter could be returned to the pelagic food web via the microbial loop represented by bacteria, ciliates and heterotrophic/mixotrophic flagellates inhabiting the lake's deep layers.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".