Non-synergistic effects of water-soluble crude oil and enhanced ultraviolet-B radiation on a natural plankton assemblage
Bibliographic record
Abstract
The present study demonstrates the effects of the water-soluble fraction (WSF) of a crude oil, enhanced ultraviolet-B radiation (UVBR: 280 to 320 nm), and the combination of WSF and enhanced UVBR on a natural plankton assemblage (<150 m) isolated from the lower St. Lawrence Estuary. To study the separate and dual effects of WSF and UVBR, 12 microcosms (9 l) were immersed in the water column of larger mesocosms (polyethylene bags; 1800 l), providing 4 treatments, each in triplicate: (1) NUVBR + WSF (natural UVBR with WSF), (2) HUVBR + WSF (enhanced UVBR with WSF), ( During 5 d we monitored the incident radiation, WSF and nutrient concentrations, abundance and production of heterotrophic bacteria and phytoplankton. Strong deleterious effects of WSF and lower effects of UVBR were observed on the phytoplankton assemblage, with a decrease in growth rates accompanied by an increase in mean cell size which reflected a perturbation of the cell division cycle. Using the NUVBR treatement as reference conditions, the above effects resulted in a reduction of 84, 79 and 60% of total abundance of the phytoplankton fraction < 20 m in the HUVBR + WSF, NUVBR + WSF and HUVBR treatments, respectively. Significant higher values of bacterial abundances were observed in the WSF-added treatments compared to NUVBR without WSF. However, bacterial thymidine incorporation exhibited diel variations, suggesting cumulative UVBR-induced DNA and/or PAHinduced DNA damages, and possible repair mechanisms with the co-occurrence of more available growth substrates from stressed phytoplankton. The absence of significant differences between both WSF-added treatments under the 2 different UVBR conditions suggests that there is no additive interaction between WSF and UVBR. This study provides therefore the first evidence of a non-synergistic interaction between both stresses, and suggests that UVBR-induced effects on marine microorganisms can be completely masked by the strong deleterious effects of soluble petroleum hydrocarbons.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| 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 teacher head, 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".