Grazing of two toxic Planktothrix species by Daphnia pulicaria: potential for bloom control and transfer of microcystins
Bibliographic record
Abstract
The role of zooplankton in the control of cyanobacterial blooms and the transfer of cyanotoxins to higher trophic levels are of great importance to the management of water resources. Many studies have focused on the cyanobacterium Microcystis, but few have examined the interactions between zooplankton and filamentous cyanobacteria. In this study, we provide experimental evidence for the potential grazing of two toxic strains of filamentous cyanobacteria, Planktothrix rubescens and P. agardhii, by Daphnia pulicaria, and for transfer of toxins in the planktonic food chain. We determined clearance rates (CRs) by adult and juvenile D. pulicaria of the two Planktothrix strains, Scenedesmus acutus and a mixture of S. acutus cells with P. rubescens culture filtrate. Filament lengths were analyzed, and microcystin (MCY) presence in Daphnia was assessed using the Protein Phosphatase-2A (PP-2A) Inhibition Assay. The two Planktothrix strains were equally grazed by D. pulicaria, but at lower CRs than S. acutus. Potential anti-grazer toxins in P. rubescens filtrate did not inhibit Daphnia grazing. Small P. rubescens (<100 μm) filaments were preferentially grazed by adult D. pulicaria, suggesting their limited ability to control a Planktothrix population during a bloom. Large quantities of MCYs were found in unstarved Daphnia previously exposed to Planktothrix, whereas quantities were significantly smaller in individuals starved for 24 h before preservation. This indicated a potential for transfer of toxins in the food chain by Daphnia, especially immediately after ingestion of toxic cyanobacteria.
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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) | 0.000 | 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".