CO2 effects on taxonomic composition and nutrient utilization in an Equatorial Pacific phytoplankton assemblage
Bibliographic record
Abstract
MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 236:37-43 (2002) - doi:10.3354/meps236037 CO2 effects on taxonomic composition and nutrient utilization in an Equatorial Pacific phytoplankton assemblage Philippe D. Tortell1,*, Giacomo R. DiTullio2, Daniel M. Sigman3, François M. M. Morel3 1Department of Ecology and Evolutionary Biology, and 3Department of Geosciences, Princeton University, Guyot Hall, Washington Road, Princeton, New Jersey 08544, USA 2University of Charleston, Grice Marine Lab, 205 Ft. Johnson, Charleston, South Carolina 29412, USA *Present address: Department of Earth and Ocean Sciences, Department of Botany, University of British Columbia, 1461-6270 University Blvd, Vancouver, British Columbia V6T 1Z4, Canada. E-mail: ptortell@eos.ubc.ca ABSTRACT: We report the results of a field incubation experiment demonstrating a substantial shift in the taxonomic composition of Equatorial Pacific phytoplankton assemblages exposed to CO2 levels of 150 and 750 ppm (dissolved CO2 ~3 to 25 µM). By the end of the experiment, the phytoplankton community in all samples was dominated by diatoms and Phaeocystis sp. However, the relative abundance of these phytoplankton taxa differed significantly between CO2 treatments. Taxonomic pigment analysis and direct microscopic examination of samples revealed that the abundance of diatoms decreased by ~50% at low CO2 relative to high CO2, while the abundance of Phaeocystis increased by ~60% at low CO2. This CO2-dependent shift was associated with a significant change in nutrient utilization, with higher ratios of nitrate:silicate (N:Si) and nitrate:phosphate (N:P) consumption by phytoplankton in the low CO2 treatment. Despite the significant changes in taxonomic composition and nutrient consumption ratios, total biomass and primary productivity did not differ significantly between the CO2 treatments. Our results suggest that CO2 concentrations could potentially influence competition among marine phytoplankton taxa and affect oceanic nutrient cycling. KEY WORDS: Diatom · Phaeocystis · Carbon dioxide · Species composition · Nutrient utilization Full text in pdf format PreviousNextExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 236. Online publication date: July 03, 2002 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2002 Inter-Research.
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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 | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 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".