Effects of Microplastic on Freshwater Benthic Ecosystems: toxicity and impacts on biogeochemical cycling
Bibliographic record
Abstract
The accumulation of plastic debris in waterways is an increasingly complex environmental problem due to the ubiquity and magnitude of plastic debris across freshwater ecosystems, along with the unknown impacts on ecosystems and public health. However, “plastic” is a catchall term for numerous polymers with unique physical and chemical properties. Further complicating the prediction of risk, plastic characteristics may change from environmental exposure, with changes in density, adsorption or leaching of toxins, and accumulation of biofilms that further influence material properties, fate and impact. Recent studies suggest that a substantial proportion of plastic entering freshwater systems is deposited in the benthos, where organisms may be exposed to plastic-associated toxins indirectly or through consumption by invertebrates and higher trophic levels. The presence of toxic materials may hinder crucial ecosystem functions carried out by microbes and invertebrates that are key drivers of benthic ecosystem function and benthic-pelagic coupling. This research addresses the diversity that exists among plastic polymers, and studies how the ecotoxicology of plastic varies both spatially and temporally in the environment. Using toxicity bioassays with the oligochaete Lumbriculus variegatus and microcosm experiments, I investigated the eco-toxicity and impacts on biogeochemistry of 6 common consumer plastics in pristine form and after aging in Lake Ontario and a stormwater pond in the watershed, and how the impacts of plastic on benthic organisms extends to impact ecosystem function. While all polymers studied had sublethal impacts on L. variegatus, there were unique impacts on nitrogen and phosphorus cycling and ecosystem metabolism among polymers. These effects shifted after environmental exposure and varied between sites, with some materials losing toxicity and others gaining, and unique impacts to biogeochemistry persisting over time. These results suggest that ecological impacts of plastic pollution are complex, varying among polymers, water bodies and exposure time.
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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 | 0.001 |
| 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 | 0.001 |
| 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".