Low Benthic Oxygen and High Internal Phosphorus-Loading are Strongly Associated With the Invasive Macrophyte Nitellopsis obtusa (starry stonewort) in a Large, Polymictic Lake
Bibliographic record
Abstract
Lake Scugog is an important headwater to the Trent Severn-Waterway in Ontario, Canada. In recent years, notable ecosystem-level changes have occurred coinciding with the emergence of the non-native invasive charophyte Nitellopsis obtusa . Despite N. obtusa arriving in North America in the early 1970s, studies documenting the impact of N. obtusa on invaded ecosystems are scarce. Given the increasing dominance of N. obtusa in inland waters of the Great Lakes basin, we investigated the ecosystem-level impacts of N. obtusa in Lake Scugog over a 3-year period. We show for the first time a strong association between N. obtusa occurrence and biomass with benthic anoxia in this shallow, polymictic lake. Benthic dissolved oxygen concentrations were significantly lower ( p -value < 0.001) at sites with N. obtusa compared to sites without N. obtusa . Additionally, N. obtusa biomass was a negative predictor of near-bed oxygen concentration ( R 2 = 0.59, p -value < 0.001). Knowing that anoxia can promote the internal loading of phosphorus, we measured soluble reactive phosphorus (SRP) in the pore-water of sediments at each site, and found N. obtusa biomass explained 90% of sediment pore-water SRP ( R 2 = 0.90, p -value < 0.001). These notable associations between N. obtusa and key lake elements indicates that N. obtusa may be acting as an ecosystem engineer in invaded lakes by altering the biogeochemical fate of oxygen and phosphorus.
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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 | 0.001 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.001 |
| 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".