Institute of Oceanography, Viet Namhttp://hdl.handle.net/1834/92462024-03-29T07:56:21Z2024-03-29T07:56:21ZFrequent occurrence of tetrodotoxin in the marine gastropod Nassarius glans causing a food poisoning in Khanh Hoa province, Vietnam in 2020Dao, Viet HaLe, Ho Khanh HyPham, Xuan KyBui, Quang NghiNguyen, Phuong AnhPhan, Bao VyDoan, Thi Thiethttp://hdl.handle.net/1834/429972024-03-27T02:35:49Z2023-01-01T00:00:00ZFrequent occurrence of tetrodotoxin in the marine gastropod Nassarius glans causing a food poisoning in Khanh Hoa province, Vietnam in 2020
Dao, Viet Ha; Le, Ho Khanh Hy; Pham, Xuan Ky; Bui, Quang Nghi; Nguyen, Phuong Anh; Phan, Bao Vy; Doan, Thi Thiet
A fatal neurotoxic poisoning case happened in Khanh Hoa province in 2020 after eating a certain number of marine gastropods, later identified as Nassarius glans, one of the common marine gastropods in Vietnam. As the remaining causative food in the incident, 62 specimens were collected to examine tetrodotoxin toxicity individual variation and frequency of toxic specimens by using HILIC/MS-MS analysis. 100% of studied specimens exhibited toxicity (556 ± 821 MU/g) beyond the regulatory level of consumption (10 MU/g) for puffer(fish) recommended in Japan and extensive variation (18–4,046 MU/g). The result pointed out that only 5 g of soft tissue from N. glans (equivalent to 2–3 specimens) containing maximum toxicity detected in the present study may cause human death if consumed. Fhe first time, this study identified TTXs in the gastropods as a causative toxin in the poisoning in Vietnam. Moreover, 65.5% of studied specimens with high toxicity higher than 100 MU/g, including 16.1%, showing extremely high toxicity (> 1,000 MU/g). The results suggested that this gastropod is quite dangerous for human consumption and should be alerted to public awareness.
2023-01-01T00:00:00ZMetabolites from the soft coral -associated bacterium Micrococcus sp. strain a-2-28Pham, Thi MienWiese, JuttaDao, Viet Hahttp://hdl.handle.net/1834/429962024-02-17T02:38:20Z2023-01-01T00:00:00ZMetabolites from the soft coral -associated bacterium Micrococcus sp. strain a-2-28
Pham, Thi Mien; Wiese, Jutta; Dao, Viet Ha
The marine actinomyces Micrococcus was the most common bacterium among the isolates corals, sponges, and alga isolates. Only a few investigations of natural compounds from Micrococcus sp. were reported previously. This study implicated the soft coral-associated Micrococcus sp. strain A-2-28 (following relative Micrococcus flavus LW4T) for large-scale cultivation, chemical analyses, and biological activities. Whereas crude extract of the strain A-2-28 inhibited only Staphylococcus epidermidis, metabolites profiles and pure compounds from strain A-2-28 showed that this strain produced phytohormone (IAA), metabolized some new compounds which were almost inactive for biological tests. This work suggested that it is possible to plan a new strategy for improving coral health and resilience though their associated microbial.
2023-01-01T00:00:00ZStatus and temporal change in the distribution of seagrass beds andcoral reefs in the waters of Phu Quoc islands, Kien Giang provinceNguyen, Van LongTong, Phuoc Hoang Sonhttp://hdl.handle.net/1834/429952024-02-17T02:38:33Z2023-01-01T00:00:00ZStatus and temporal change in the distribution of seagrass beds andcoral reefs in the waters of Phu Quoc islands, Kien Giang province
Nguyen, Van Long; Tong, Phuoc Hoang Son
To assess the status and changes in the distribution of seagrass beds and coral reefs in Phu Quoc from 2005 to 2018, we utilized high-resolution multi-spectrum satellite images, aerial photographs, and Google maps. We collected data from three time periods: 2005 (using ASTER with 15 m resolution), 2010 (using SPOT5 with 10 m resolution), and 2018 (using SENTINEL-2 with 10 m resolution). We also conducted an accuracy assessment of 78 key sites in March-April 2019, representing corals (25 sites), seagrasses (28 sites), rocks (8 sites), and sand (12 sites) through SCUBA diving. The results showed that in 2018, the waters of Phu Quoc contained 513 ha of coral reefs and 10,035 ha of seagrass beds, with 290 ha of coral reefs and 9,185 ha of seagrass beds located within the Phu Quoc marine protected area. While the area of coral reefs remained stable between 2005 and 2018, the seagrass beds experienced a significant decline of 652 ha (6.1%), with most losses occurring at Bai Vong (501 ha; 4.69%), Ong Doi cape - Dam Ngoai island (55 ha; 0.52%), Mot Island and Vinh Dam (42 ha; 0.4% each), and Da Chong cape (12 ha; 0.12%). This decline is largely due to recent infrastructure development for community and tourism purposes, which has caused the degradation of seagrass beds.
2023-01-01T00:00:00ZMacrobenthic community status at coastal cage aquaculture area in Xuan Dai bay, Phu Yen province, VietnamPhan, Thi Kim HongNguyen, Ngoc Anh ThuDao, Tan HocNguyen, An KhangHua, Thai TuyenMai, Xuan DatHo, Thi Hoahttp://hdl.handle.net/1834/423942022-11-16T02:04:51Z2022-01-01T00:00:00ZMacrobenthic community status at coastal cage aquaculture area in Xuan Dai bay, Phu Yen province, Vietnam
Phan, Thi Kim Hong; Nguyen, Ngoc Anh Thu; Dao, Tan Hoc; Nguyen, An Khang; Hua, Thai Tuyen; Mai, Xuan Dat; Ho, Thi Hoa
Lobster cage culture started around 1990 in Xuan Dai bay and grew fast in recent years, contributing significantly to the socio-economic development of the region. But the impact on the ecological environment of cage culture operation also needs to consider. This paper points out the status of the macrobenthic community, studied at two stations inside the cage culture area (X1, X2) and one reference station (Xr) in the non-cage culture area. A total of 90 samples with 5 replicate samples per station were collected in six surveys during the dry and rainy seasons from June 2019 to May 2020. These samples were classified and recorded into 80 taxa belonging to 49 families and 5 classes. The class Polychaetes had the most diverse species composition with 53 taxa (66% of the total number of taxa). The crustacean group had 14 taxa (18%) belonging to 13 families; Molluscs had 9 taxa (11%) belonging to 6 families of class Bivalvia. The echinoderms had 4 taxa (5%). Capitella capitata, a species known as an indicator of organic pollution, was recorded in both stations of the culture area but was not present at the reference station. Furthermore, some dominant species presented in the culture stations such as Cossura longocirrata (contributed 43.52% in station X1) and Ceratonereis sp. (contributed 27.57% in station X2). These species are considered opportunistic species that can adapt to disturbed environmental conditions. Significantly, the species of echinoderms group were only recorded in the reference station. The species composition was only about 24% similar to those at the cage culture stations. The species richness index (D) values ranged from 1.50 (X2.6) to 6.82 (Xr.3). The diversity index (H′) varied from 0.88 (X2.4) to 2.98 (Xr.3). The evenness index (J) had the lowest average value at station X2 (J = 0.59 ± 0.20) and the highest value at the reference station Xr (J = 0.78 ± 0.03). The indices D, H′ and J of the macrobenthic community at the reference stations have higher average values compared to those estimated at cage culture stations. These results proved cage culture activities have gradually impacted the benthic fauna, reduced biodiversity, and encouraged the appearance of opportunistic species. Thus, further studies on the macrobenthic community dynamic with ecological criteria are necessary to establish a set of biological indicators to monitor the environmental quality of the coastal aquaculture area.
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