Decline and regional extirpation of freshwater mussels (Unionidae) in a small river system invaded by <i>Dreissena polymorpha</i>: the Rideau River, 19932000
Bibliographic record
Abstract
Data pertaining to the ecological impact of the exotic zebra mussel, Dreissena polymorpha, on benthic fauna in small river systems are scarce. We conducted a long-term study to assess the impacts of the D. polymorpha invasion in a small river system (100 km) in eastern Ontario during an 8-year period (19932000). A 30-km downstream section of the Rideau River was studied before and during rapid population growth of D. polymorpha in the area. During 19931995, D. polymorpha abundance on hard substrates increased by four to six orders of magnitude and remained high thereafter. A comparable temporal pattern of D. polymorpha abundance was observed on shells of live freshwater mussels (Unionidae). During peak fouling (19951997), mass ratios (mass of attached D. polymorpha / mass of live unionid host) ranged from 0.37 to 1.81. SCUBA-diving surveys (50-m transects) were conducted to examine the impact of D. polymorpha on native unionids in impounded river habitats. In 19931994, three unionid taxa were commonly found in 10-m2 quadrats sampled along transects: Elliptio complanata, Pyganodon grandis, and Lampsilis radiata. Overall, the mean density of unionids declined 5- to 8-fold from 1993 to 1997, coinciding with a rapid increase in D. polymorpha densities on unionids. By 1997, i.e., 4 years after fouling began, P. grandis and L. radiata had been extirpated from those sites, with only E. complanata remaining. By 2000, i.e., 7 years after fouling began, all three unionid taxa had been essentially extirpated from the 30-km section of the river, with only one live individual (E. complanata) collected during 10 extensive diving surveys (the total estimated area of riverbed surveyed was 4000 m2). This study indicates that heavy fouling by D. polymorpha causes the extirpation of unionids in small impounded river systems ([Formula: see text]100 km).
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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 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.001 | 0.001 |
| 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".