Benthic Responses to Wet-Weather Discharges in Urban Streams in Southern Ontario
Bibliographic record
Abstract
Abstract Urban stormwater and combined sewer overflow (CSO) discharges are important sources of sediment and contaminants (trace metals, PAHs, nutrients and road salts), and cause changes in flow, sediment, chemical and thermal regimes of receiving waters. Over the past several years, benthic conditions of streams representing a range of exposure environments were assessed in Hamilton, Toronto, Oshawa and Kingston, Ontario. Studies progressed from initial surveys of sediment contaminant levels, sediment toxicity and benthic invertebrate community structure to more spatially intensive sampling and experimental approaches that included the use of artificial substrates, in situ water toxicity tests and measurements of contaminant bioaccumulation. Results showed that while sediments and some biota at sites exposed to wet-weather discharges were often contaminated with metals and PAHs and enriched with nutrients, significant biological degradation measured by sediment toxicity or depauperated benthic communities was not evident. Exposure to stormwater discharges at sites below outfalls could alter the composition of benthic communities, but these effects were not strongly related to contaminant concentrations in sediment or invertebrate tissue. No outfall-associated toxicity was observed for caged amphipods held in the water column. Effects of wet-weather discharges on benthic communities at the urban stream sites studied appear to be small, and their detection was limited by several inherent conditions, including natural heterogeneity in the distribution of benthic invertebrates, episodic (intermittent) exposure to discharges and contaminant fluxes allowing some recovery, “background” levels of disturbance, poorly delineated changes in communities caused by physical effects such as flow and sediment transport, and community response dynamics. Detection of stormwater discharge effects should be improved by sampling on smaller temporal and multiple spatial scales to better quantify stressor exposure and invertebrate responses.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
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 | 0.001 |
| 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".