Ammonia may play an important role in the succession of cyanobacterial blooms and the distribution of common algal species in shallow freshwater lakes
Bibliographic record
Abstract
Abstract With the human intensification of agricultural and industrial activities, large amount of reduced nitrogen enter into the biosphere, which consequently results in the development of global eutrophication and cyanobacterial blooms. However, no research had reported the effect of ammonia toxicity on the algal succession. In this study, we investigated the ammonia toxicity to 19 algal species or strains to test the hypothesis that ammonia may regulate the succession of cyanobacterial blooms and the distribution of common algal species in freshwater lakes. The bloom‐forming cyanobacteriumMicrocystis aeruginosaPCC 7806 suffered from ammonia toxicity at highpHvalue and light intensity conditions. Low NH4Cl concentration (0.06 mmol L−1) resulted in the decrease of operational PSII quantum yield by 50% compared with the control exposed to 1000 μmol photons m−2 s−1for 1 h atpH9.0 ± 0.2, which can be reached in freshwater lakes. Furthermore, the tolerant abilities to NH3toxicity of 18 freshwater algal species or strains were as follows: hypertrophication species > eutrophication species > mesotrophication species > oligotrophication species. The different sensitivities of NH3toxicity in this study could well explain the distributing rule of common algal species in the freshwater lakes of different trophic states. Meanwhile, the cyanobacterial bloom (e.g.M. aeruginosa) always happened at the low concentration of ammonia in summer, and disappeared with the decrease of ammonia. This may be attributed to the toxic effect of ammonia toM. aeruginosain spring (the average and maximum ammonia concentration were 0.08 and 0.72 mmol L−1in 33 Chinese lakes), and the low level of NH3‐N in summer and fall in the lakes might be used as preferred nitrogen nutrition byM. aeruginosa, rather than with toxicity. Therefore, ammonia could be a key factor to determine the distribution of common algal species and cyanobacterial bloom in the freshwater systems.
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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".