Effect of nutrients and salinity pulses on biomass and growth of <i>Vallisneria americana</i> in lower St Johns River, FL, USA
Bibliographic record
Abstract
We determined the interactive effects of nutrient loading and salinity pulsing on Vallisneria americana Michx., the dominant submerged aquatic vegetation species in the lower St Johns River (LSJR), FL, USA, and its associated algal community. Five hundred and ninety 6-inch diameter intact plant plugs of Vallisneria were collected from the LSJR in March 2003 and transported to US Geological Survey mesocosm facilities in Lafayette, LA, USA. A 3×3 experimental design consisting of three nutrient levels (control, 1/3 control and 3× control) and three salinity pulsing regimes (no pulse, 1-pulse at 18 ppt and 2-pulse at 12 and 18 ppt) was implemented with three replicates per treatment for a total of 27 experimental tanks. Salinity pulsing significantly reduced all measured Vallisneria growth parameters including above- and below-ground biomass, areal productivity and leaf area index. Nutrient levels had little effect on plants subjected to salinity pulses, but in non-salinity pulse treatments we observed higher mean macrophyte biomass in the low-nutrient loading treatments. Macroalgal components (epiphytes and surface algal mats) were not significantly different ( p=0.2998 and p=0.2444, respectively), but water column chlorophyll a (phytoplankton) was significantly higher ( p<0.0001) in all salinity pulse treatments except for the 1-pulse, low-nutrient treatment. A single salinity pulse at 18 ppt resulted in 22% pot mortality and two consecutive pulses of 18 and 12 ppt resulted in an additional 14% mortality. Individual leaves and ramets lost 59.7% and 67.8%, respectively, in the combined salinity pulse treatments. Nutrient loading tends to have a long-term effect on Vallisneria through complex community interactions while salinity pulsing frequency and intensity has an immediate and direct influence on growth and distribution.
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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 | 0.001 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| 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".