Co-Occurrence of Cyanotoxins and Phycotoxins in One of the Largest Southeast Asian Brackish Waterbodies: A Preliminary Study at the Tam Giang—Cau Hai Lagoon (Vietnam)
Bibliographic record
Abstract
The Tam Giang-Cau Hai lagoon (TGCH) in Thua Thien Hue province (Vietnam) is a marsh/lagoon system and ranks among the largest waterbodies in Southeast Asia. It plays a significant role in terms of both socio-economic and environmental resources. However, anthropogenic stress, as well as the discharge of untreated domestic and industrial sewage with agricultural runoff from its three major tributaries, dramatically damages the water quality of the lagoon. Especially after heavy rain and flash floods, the continuous degradation of its water quality, followed by harmful algal and cyanobacterial bloom patterns (HABs), is more perceptible. In this study, several physicochemical factors, cyanotoxins (anatoxins (ATXs), saxitoxins (STXs), microcystins (MCs)), phycotoxins (STXs, okadaic acid (OA), and dinophysistoxins (DTXs)) were analyzed in water and shellfish samples from 13 stations in June 2023 from 13 stations, using enzyme-linked immunosorbent assay (ELISA) kits for the ATXs and STXs, and the serine/threonine phosphatase type 2A (PP2A) inhibition assay kit for the MCs, OA, and DTXs. The results showed for the first time the co-occurrence of freshwater cyanotoxins and marine phycotoxins in water and shellfish samples in this lagoon. Traces of ATXs and STXs were detected in the shellfish and the orders of magnitude were below the seafood safety action levels. However, toxins inhibiting the PP2A enzyme, such as MCs and nodularin (NODs), as well as OA and DTXs, were detected at higher concentrations (maximum: 130.4 μg equiv. MC-LR/kg shellfish meat wet weight), approaching the actionable level proposed for this class of toxin in shellfish (160 μg of OA equivalent per kg of edible bivalve mollusk meat). It is very important to note that due to the possible false positives produced by the ELISA test in complex matrices such as a crude shellfish extract, this preliminary and pilot research will be repeated with a more sophisticated method, such as liquid chromatography coupled with mass spectroscopy (LC-MS), in the upcoming research plan.
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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 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 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) | 0.000 | 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 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".