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. 2018 Nov 14;10(11):471.
doi: 10.3390/toxins10110471.

Cyanobacterial Blooms and Microcystins in Southern Vietnam

Bui Trung  1   2 , Thanh-Son Dao  3 , Elisabeth Faassen  4 , Miquel Lürling  5   6
Affiliations

Cyanobacterial Blooms and Microcystins in Southern Vietnam

Bui Trung et al. Toxins (Basel). .

Abstract

Studies on cyanobacteria in Vietnam are limited and mainly restricted to large reservoirs. Cyanobacterial blooms in small water bodies may pose a health risk to local people. We sampled 17 water bodies in the vicinity of urban settlements throughout the Mekong basin and in southeast Vietnam. From these, 40 water samples were taken, 24 cyanobacterial strains were isolated and 129 fish, 68 snail, 7 shrimp, 4 clam, and 4 duck samples were analyzed for microcystins (MCs). MCs were detected up to 11,039 µg/L or to 4033 µg/g DW in water samples. MCs were detected in the viscera of the animals. MC-LR and MC-RR were most frequently detected, while MC-dmLR, MC-LW, and MC-LF were first recorded in Vietnam. Microcystis was the main potential toxin producer and the most common bloom-forming species. A potential health hazard was found in a duck⁻fish pond located in the catchment of DauTieng reservoir and in the DongNai river where raw water was collected for DongNai waterwork. The whole viscera of fish and snails must be completely removed during food processing. Cyanobacterial monitoring programs should be established to assess and minimize potential public health risks.

Keywords: Mekong river; aquaculture; cyanobacteria; cyanotoxins.

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Conflict of interest statement

The authors declare no conflict of interest.

Figures

Figure A1
Figure A1
Correlation between cyanobacteria Chl-a concentration (µg/L) and TN (mg/L). Pearson = 0.709.
Figure A2
Figure A2
Correlation between cyanobacteria Chl-a concentration (µg/L) and TP (mg/L). Pearson = 0.676.
Figure 1
Figure 1
Daily activities of local people potentially exposed to cyanobacterial toxins in the Mekong Delta: Traditional fisheries in cyanobacteria bloom-water ponds (a,b) and bathing and washing (c,d).
Figure 2
Figure 2
Estimated contribution of eight microcystin (MC)-variants to the total MC toxicity in 18 surface water samples with cyanobacterial bloom in southern Vietnam.
Figure 3
Figure 3
Microscopy revealed that fecal pellets of fish in a fish pond in BinhChanh contained undigested Microcystis and rotifer.
Figure 4
Figure 4
The typical process scheme of a water drinking plant in Vietnam. Modified from Nha Trang et al., 2012 [47]. RW: Raw water; WI: Effluent of pre-chlorination; MT: Effluent of mixing tank; ST: Effluent of the sedimentation tank; SF: Effluent of rapid sand filter; RI: The inlet of the clean water reservoir; PS: The outlet of the clean water reservoir.
Figure 5
Figure 5
Locations of the sampling sites in South Vietnam. Black dots indicate positions where cyanobacterial blooms occur and the samples were collected.
See this image and copyright information in PMC

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