Application of Same-Day Enterococcus qPCR-Based Analyses for Quality Assessment of Shorelines (Water and Sand) at Recreational Beaches
Bibliographic record
Abstract
Rapid water-quality monitoring methods for beach water and sand can be helpful for public health authorities to develop comprehensive beach monitoring programs. In this study, we evaluated the performance of the Enterococcus qPCR (USEPA 1609.1) method for quality monitoring of beach water and sand-porewater at two Niagara region beaches in Ontario, Canada (Lakeside and Sunset Beaches). While the USEPA 1609.1 method has been validated for beach water, its potential for assessing associated beach sands (which may function as a microbial reservoir) has not been fully explored. All beach water samples (n = 168) passed the qPCR quality control (QC). However, only 20 out of 48 (41.7%) sand-porewater samples passed the qPCR QC, potentially due to interference by soluble inhibitors. The proportion of the sand-porewater samples passing QC improved slightly to 63 out of 120 (52.5%) with a prefiltration step to remove sand and other large particles. The faecal indicator density in the sand-porewater, tested in parallel, did not correlate with the beach water faecal indicator density. Comparing beach water data for the same-day Enterococcus qPCR threshold with the previous-day E. coli culturing-based threshold across all beach days tested, Enterococcus qPCR analyses identified 3 (7%) and 7 (16%) false positive/lost beach days for Lakeside and Sunset Beaches, respectively. Additionally, of the total beach days tested, Enterococcus qPCR analyses identified 2 (5%) and 1 (2%) false negative/health-risk days for Lakeside and Sunset Beaches, respectively. Sand-porewater testing analyses identified days when faecal indicators (in the sand) exceeded beach water quality thresholds. Compared with conventional E. coli culturing, use of the same-day qPCR method would result in fewer beach postings and could identify several additional health-risk days (when the beaches may not be posted). Future studies could include additional prefiltration steps or modifications in the Enterococcus qPCR protocol to improve the method’s applicability for sand quality monitoring.
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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 | 0.001 | 0.001 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| 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".