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    • Frequent 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 (2023)
      Vietnam journal of marine science and technology
      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.
    • Metabolites from the soft coral -associated bacterium Micrococcus sp. strain a-2-28

      Pham, Thi Mien; Wiese, Jutta; Dao, Viet Ha (2023)
      Vietnam journal of marine science and technology
      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.
    • Status 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 (2023)
      Vietnam journal of marine science and technology
      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.
    • Macrobenthic 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 (2022)
      Vietnam of Journal Marine Science and Technology
      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.
    • Fluctuation of associated microbial with building reef corals Acropora sp. from Hang Rai, Ninh Thuan

      Pham, Thi Mien; Vo, Hai Thi; Nguyen, Kim Hanh (2022)
      Vietnam of Journal Marine Science and Technology
      El Niño and the prolonged warm sea surface temperature significantly impacted coral reefs and caused coral bleaching in some parts of the world. This study evaluated the density of symbiotic algae and bacteria associated with the three coral species, namely Acropora hyacinthus, Acropora muricata, and Acropora robusta, collected in Hang Rai, Ninh Thuan in May, June, August 2016, and June 2017. The number of zooxanthellae with each coral species was statistically significant and correlated with several environmental factors, suggesting that symbiotic algae could play a key role in coral health. The number of associated microbial with the three coral species was significantly different; they tended to depend on sampling time rather than coral species-specific. At the time of ENSO (2016), the difference in the total associated bacteria with all three coral species was statistically significant. While the total number of related bacteria with all three species of coral collected in 2017 did not differ from the total of bacteria in ambient water. In conclusion, symbiotic algae tend to be species-specific, whereas bacteria fluctuate significantly over sampling time. Studying the molecular issues of microalgae, the presence, the role of some groups of bacteria involved in the N, C, P, and S cycles, and the influence of environmental parameters should also be encouraged to understand the relationship of coral holobiont better.
    • Morphological variation and haplotype diversity of Halimeda macroloba and H. opuntia (Chlorophyta: Halimedaceae) from Southern Vietnam

      Nguyen, Trung Hieu; Nguyen, Nhat Nhu Thuy; Nguyen, Xuan Thuy; Nguyen, Xuan Vy (2022)
      Vietnam of Journal Marine Science and Technology
      Plasticity in morphology is a common phenomenon of aquatic plants. Halimeda (Chlorophyta: Halimedaceae) is usually supersaturated with calcium carbonate and is found in tropical and subtropical regions. Among members of Halimeda, both species including Halimeda macroloba and H. opuntia, often occur in different habitats. Haplotype diversity and network of Halimeda were reported in the different sea and oceanic systems. However, there are no reports of the genetic diversity of Halimeda in Vietnamese waters. This present study carried out sample collections along the coast of Southern Viet Nam, including the coast sites, offshore islands, and Spratly (Truong Sa) islands. External morphological and anatomical characteristics of two dominant species, Halimeda macroloba and H. opuntia, were caparisoned. The genetic marker tufA was applied to find the haplotype diversity and network among Vietnamese and worldwide populations. The results showed that high morphology exists in both species. In contrast, the genetic variation in H. macroloba is very low, and H. opuntia tends to form a distinct group. We suggest that more samples of two species from other locations in Northern Vietnam be included.
    • Upwelling phenomenon in the marine regions of Southern Central of Vietnam: a review

      Bui, Hong Long; Phan, Minh Thu (2022)
      Vietnam of Journal Marine Science and Technology
      Upwelling is an oceanographic phenomenon that involves the physical process and contributes to changes in chemistry, biology, and natural resources. So, systematically, it is the particular ecosystems of whole marine regions with the upwelling. The strong upwelling waters in South Central Regions of Vietnam have uncertain features of the East Vietnam Sea (Bien Dong) and special characteristics of a coastal upwelling area, recorded in international scientific papers in the twentieth century. Their first signals were discovered in the early 1930s through conceptual ideas. The upwelling phenomenon is officially confirmed by scientific results of marine investigations of the NAGA Expedition (1959–1961). The paper aims to review and discuss the physical from Vietnamese investigation and results since 1990s. The following factors are the most contributing to forming and developing the strong upwelling in Southern Central Waters: (1) Influence scale (Mezo- and micro-scale); (2) Forming causes and developing mechanism of upwelling phenomenon, such as monsoon, morphography, shoreline, and western boundary current system of the East Vietnam Sea; (3) Influence of the water-mass from Mekong River on the upwelling area; (4) Ecological environmental consequences; (5) Impacts of the atmospheric-oceanic interaction processes on the western EVS on upwelling. Additionally, the review has targeted findings of upwelling phenomenon mainly in Vietnamese waters based on remote sensing analysis and reanalysis data series to simulate their forming, mechanizing, fluctuating models and the impacts of upwelling in the EVS on resources and ecosystems. The coupled atmosphere-ocean models resulted the upwelling mechanisms and formation. The long-time series of upwelling phenomenon (Macroscale) were evaluated by remote sensing and reanalyzed data series. It is also providing the supplementing and detailing causes and mechanisms of upwelling formation; impacts and interactions of upwelling on marine physics and hydrodynamics (ocean vortexes, seawater temperature), biochemical (nutrients, plankton organisms), and resources (fish, seafood). Within the framework of strong upwelling waters in the Southern Central Regions (Vietnam), the review has not only mentioned partly clarified scientific results but also indicates the limitations and challenges which were faced and encountered in the forecasters of upwelling phenomena in the future.
    • Water quality at Cai river mouth and Tac river mouth, Nha Trang bay (2015–2019)

      Pham, Hong Ngoc; Le, Hung Phu; Do, Anh Van; Nguyen, Hong Thu; Le, Trong Dung; Dao, Viet Ha (2022)
      Vietnam of Journal Marine Science and Technology
      Deltas of large rivers, especially in arid areas, have been used in ancient times for agriculture and are densely populated. In recent decades, many river deltas have been experiencing an increasing anthropogenic impact, contamination of watersheds, and marine pollution caused by the offshore extraction of hydrocarbons. Combining of these factors determines a considerable research interest in river mouth areas. This paper presents the annual monitoring data on the water environment of the two mouths of the Cai river and Tac river, Nha Trang bay, during the period 2015–2019. Statistical data showed an increase in dissolved oxygen demand (DO), biological oxygen demand BOD5, and the concentrations of ammonia, Zn and Cu. Seasonal variation revealed that most of studied parameters’ concentrations, especially nutrients, were higher in the rainy season. In contrast, the values of total suspended solids (TSS) and hydrocarbon (Cai River), and petroleum (Tac river) demonstrated a decrease. Generally, the average value of BOD5, concentrations of Cu and Pb at the Cai river mouth were lower than those at the Tac river mouth, whereas the concentration of Zn was higher. Overall, the water environment of both mouths was qualified for aquaculture and aquatic organism preservation purposes except for the case of coliform.
    • A study on the spawning season of 3 Acropora species in Nha Trang bay, Southern waters of Vietnam

      Vo, Si Tuan; Ho, Son Lam; Dang, Tran Tu Tram; Phan, Kim Hoang; Doan, Van Than; Mai, Xuan Dat (2022)
      Vietnam of Journal Marine Science and Technology
      Specimens for the study on coral spawning of three species were collected at two sites in Nha Trang bay, South Vietnam, in 2014, 2015, 2016, 2018 and 2019. The determination of spawning seasons was based on observations of gonadogenesis development of A. florida and A. robusta and variation of egg average sizes of these two species and A. hyacinthus. Data analysis and comparative discussions allow us to assume that the 3 Acropora species exhibited single cycle spawning annually and their spawning period occurred in March/April between the full moon and crescent moon. However, their maturity periods were not the same, starting before and ending after the full moon for A. florida and A. robusta but starting after the full moon and lasting until the crescent moon for A. hyainthus. Further studies are needed to improve the understanding of coral spawning and support coral restoration using sexual reproduction.
    • Zooplankton assemblages in De ghi lagoon, Binh Dinh province

      Nguyen, Tam Vinh; Doan, Nhu Hai (2021)
      Collection of Marine Research Works
      This paper presents the results of zooplankton surveys in De Gi lagoon 2009, 2010, and 2020. Change of zooplankton communities was analyzed based on species richness, diversity, abundance, and species composition over the three sampling time points. In De Gi lagoon, the copepod group (subclass Hexanauplia) dominated with 61 in 85 zooplankton identified species, followed by Hydrozoa and Malacostraca with seven and five species, respectively. The remaining groups (Polychaeta, Branchiopoda, Ostracoda, Sagittoidea, Appendicularia, Thaliacea, Tentaculata, and Gastropoda) had low species richness, varied from 1 to 2 species. The Copepod assemblages compose mainly small species and have good adaptation in high salinity variabilities, such as Paracalanus and Acartia. In the lagoon, species richness and diversity increased from the upper lagoon to the lagoon's mouth over the years, but most pronounced in 2020. The average zooplankton density this year was low, 9.136 inds.m-3, much lower than in 2009 with 54.022 inds.m-3. Cluster analysis demonstrated the complexity of the zooplankton structure in the lagoon when the similarity in species composition between seasons and years is ca. 27%. Seasonal changes in zooplankton assemblages presented 58-73% dissimilarity, with the dry season having higher diversity, biomass, and calanoid copepodites and larvae. After ten years, since 2010, the zooplankton assemblages differed by 60-72% with higher diversity and lower abundance but remained similar ratios between dominant Calanoida and other orders in the copepod assemblages. Invertebrate larval abundance in De Gi lagoon should be considered as an important resource for their dominance and variation between seasons and distribution. This research provides basic scientific data on the zooplankton communities of De Gi lagoon, which has not been published before, contributing the baseline to any further studies the South-Central Viet Nam.
    • Composition and distribution seaweeds in Thuyen Chai island (Truong Sa islands-Vietnam)

      Nguyen, Trung Hieu; Hoang, Xuan Ben; Hoang, Thi Thuy Dung (2021)
      Collection of Marine Research Works
      Thuyen Chai Island, located in the South of the Spratly Archipelago (Vietnam), features a seagrass bed, coral reef ecosystem, and a tidal zone. All of these causes contribute to the expansion of seaweed diversity. This report gives the first findings of the seaweed flora in the rainy season. The results of the survey revealed 82 species of seaweed belong to 4 phyla. Among them, there are 42 species of Rhodophytes (comprising 51% of total species), 14 Chlorophytes (17%), 21 Ochrophytes (26%) and 5 Cyanobacteriophytes (6%). The findings show that the composition of seaweed species on Thuyen Chai island varies depending on the habitats of coral reefs and seagrass beds.
    • Species composition and density free-living marine Nematoda in coastal tidal areas of Khanh Hoa province

      Nguyen, Ngoc Anh Thu; Hoang, Xuan Ben; Bui, Quang Nghi; Nguyen, Kha Phu; Nguyen, Thi My Ngan; Vo, Thi Thuy Linh; Vu, Thi Lieu; Nguyen, Thanh Tam (2021)
      Collection of Marine Research Works
      The paper presents species composition and density of free-living nematodes marine in coastal tidal areas of Nha Trang, Khanh Hoa. 27 species was found, belonging to 11 families, 25 genera and three orders. The family Oxystominidae has the highest number of individuals (25.35%). The diversity index of the Nematode community is H'=1.83 on average, and the average density of nematodes is 75±26,23 (individuals/10cm²). The highest density of nematodes is located in the subtidal zone infralittoral fringe Hon Chong HC_3 (253 individuals/10cm). Initially, the results indicate bottom sediment significantly affects the density of individuals and the diversity of species composition of free-living marine nematodes in coastal tidal areas of Khanh Hoa province.
    • A study of dispersal patterns of reef corals in Vietnam under the influence of current regime of Bien Dong

      Vo, Si Tuan; Tran, Van Chung (2021)
      Collection of Marine Research Works
      Recognizing the flow regime in the breeding season is the dominant factor for the marine biota, a flow diagram of the Bien Dong (East Vietnam Sea) in the transitional season has been established to examine the relationship between the current and its distribution and diversity of reef-forming coral in the sea of Vietnam. The data source for modeling the current regime is updated from the Climate Forecast System Reanalysis of the National Center for Environmental Prediction (NCEP CFSR) and exploited from the HYCOM + NCODA Global 1/12.5 database for the period 1993-2012 and of HYCOM + NCODA Global 1/12o Analysis for the period from 2013 to 2020. Along with that, the finite element method (FEM) was used to build a 3D hydrodynamic model. Based on the constructed flow diagram, the dispersal capacity of coral larvae in each sea area is assessed to compare with previous observations on the species diversity of reef-forming corals. The finding includes: (1) the Gulf of Tonkin and Gulf of Thailand exhibit poor exchange and lower diversity than the continental shelf and coastal waters of Vietnam; (2) Cape Varella is a vital boundary dividing the East Vietnam Sea, forming the most diverse areas in good exchange conditions of water bodies in the south of the 13°N parallel, including the Truong Sa (Spratly) Islands. This system can be considered as part of the Coral Triangle in the Bien Dong.
    • Status and temporal changes in reef fish communities in Hon Cau marine protected area, Binh Thuan province

      Mai, Xuan Dat; Nguyen, Van Long; Phan, Thi Kim Hong; Hoang, Xuan Ben (2021)
      Collection of Marine Research Works
      A study on the status and temporal changes in communities of coral reef fishes in Hon Cau Marine Protected Area was carried out at 12 reef sites in August 2020 in combination with the data from previous studies. A total of 351 species belonging to 128 genera and 45 families of coral reef fish were recorded. The average density in 2020 was 237.3 ± 82.8 individuals/100m2, mainly occupied with small-sized fishes (accounting for 86.8% of total density) and ornamental fish, with the dominant families of damselfishes, wrasses, and cardinalfishes, while the the large-sized fish accounts for a very low rate. Target fishes were found in very low density and dominated by herbivorous feeders (especially rabbitfishes). The area around Hon Cau Island have species diversity (accounting for 94.4% of total species recorded in 2020) and a density of reef fish compared to the Breda shoal and coastal areas. The analysis results show that there were three distinguished assemblages of reef fishes, in which the reef fish communities around Hon Cau Island are different from the shoal and coastal areas. After nearly ten years of establishing Hon Cau MPA, coral reef fish density is maintained relatively stable in the area around Hon Cau Island and significantly decreased in Breda shoal and the coastal areas. There is an increase in the density of herbivorous fishes, while the large-sized and inextricably linked to the coral reef (groupers, snappers, sweetlips, butterflyfishes) with very low or reduced densities over time.
    • Common diseases in clownfish: a review

      Ho, Son Lam; Nguyen, Thi Nguyet Hue (2021)
      Collection of Marine Research Works
      Iron is a trace element involved in many physiological and biochemical processes of aquatic animals and is necessary for the production and normal functioning of hemoglobin, myoglobin, cytochromes, and many other enzyme systems, maintains the structural integrity of the epithelium and thus suppresses pathogens, iron deficiency induces microcytic anemia in certain fish species, iron-free content in mucus membranes and in other tissues that are one of the first glands to protect the host against infection, iron deficiency can decrease host resistance so that iron supplementation increases host resistance disease. This report not only reviews the iron requirement in fish and crustaceans farming but also its effect on the health status.
    • Effect efficiency of the fragmentation method to asexual reproduction of Stichodactyla haddoni

      Dang, Tran Tu Tram; Dao, Thi Hong Ngoc; Nguyen, Thi Nguyet Hue; Ho, Son Lam; Dinh, Truong An; Doan, Van Than; Nguyen, Truong Tan Tai; Do, Hai Dang; Phan, Kim Hong (2021)
      Collection of Marine Research Works
      This study examines the effect of half and quarter separation methods by fragmentation for culture sea anemone Stichodactyla haddoni (with mouth diameter 28.97±1.37 cm, foot diameter 9.39±0.44 cm, weight 1466.78 ± 192.13g) after 90 days in recirculating aquaculture systems. Research using a completely randomized design with three treatments: control, 1 to 2 individuals and 1 to 4 individuals. Each treatment repeated three replications. The results show that the survival was high, with 88.89±11.111% in control and 88.89 ±5.556% in the anemones cut in half, and 72.22±2,778 % cut in quarters (p>0.05). There was a difference in growth in mouth diameter (p<0.05) but no difference in growth in foot diameter and wet weight (p>0.05). Anemones were cut in half larger, less stressed, and grow faster than the quartered individuals, but the number of anemones from the quaternary separation method was higher. Experiments show that both fragmentation methods are highly effective and can be used to breed Stichodactyla haddoni anemone.
    • Effects of different microalgal diets on intensive cultuvation of Cyclopoida copepod Apocyclops sp.

      Hua, Thai An; Nguyen, Trung Kien; Huynh, Minh Sang; Do, Huu Hoang; Ho, Thi Hoa; Cao, Van Nguyen (2021)
      Collection of Marine Research Works
      Effects of different microalgal diets include Nannochloropsis oculata, Isochrysis sp. and Chaetoceros muelleri on mass culture of copepod Apocyclops sp. was conducted under five treatments (3 replicates) and the experiment lasted 25 days, treatment 1 (N. oculata), treatment 2 (N. oculata and Isochrysis sp., 1:1), treatment 3 (N. oculata : Ch. muelleri, 1:1), treatment 4 (Isochrysis sp. and C. muelleri, 1:1), treatment 5 (N. oculata, Isochrysis sp. and C. muelleri, 1:1:1). The results investigated that copepod fed mixing microalgal diets had better population growth than copepod fed N. oculata only. The highest density of copepod was detected in treatment 3 and 5 with 194.44 ± 101.84 and 194.44 ± 67.36 individuals/ L, respectively, these number were significantly higher than the density of copepod in treatment 1 with 67.67 ± 47.14 inds/ L (P<0.05) but no significantly different with the density of copepod in treatment 2 (105.56 ± 16.67 inds/ L) and treatment 4 (155.56 ± 67.36 inds/ L) (P>0.05).The highest population growth was in cultivation period from 15 to 20 days after that the copepod densities will be reduced. The results of fatty acid analysis showed that the highest DHA and EPA content was in treatment 3 with 32.15 and 16.34%, respectively. The lowest DHA content was in treatment 2 with 27.97% and the lowest EPA was in treatment 1 with 11.84%. The highest and lowest ratio of DHA/EPA was found in treatment 1 with 2.41 and treatment 2 with 1.93, respectively. The highest ratio of EPA/ARA was in treatment 4 with 2.21 and lowest in treatment 5 with 1.95. Based on the results of this study, N. oculata, and C. muelleri is recommended for intensive cultivation of Apocyclops sp.
    • An overview of the use of the iron in aquaculture

      Ho, Son Lam; Dang, Tran Tu Tram (2021)
      Collection of Marine Research Works
      Iron is a trace element involved in many physiological and biochemical processes of aquatic animals and is necessary for the production and normal functioning of hemoglobin, myoglobin, cytochromes, and many other enzyme systems, maintains the structural integrity of the epithelium and thus suppresses pathogens, iron deficiency induces microcytic anemia in certain fish species, iron-free content in mucus membranes and in other tissues that are one of the first glands to protect the host against infection, iron deficiency can decrease host resistance so that iron supplementation increases host resistance disease. This report not only reviews the iron requirement in fish and crustaceans farming but also its effect on the health status.
    • Environmental assessment of coastal water of Can Gio district - Ho Chi Minh city by sea water quality index

      Nguyen, Hoang Thai; Nguyen, Phi Uy Vu; Bui, Duc Linh; Nguyen, Phi Khanh Phong (2021)
      Collection of Marine Research Works
      Assessment of water quality plays an essential role in controlling and monitoring environmental quality for economic development. Based on the monitoring results in 2018-2019, the paper aims to classify the water quality based on SQWI in the coastal waters of Can Gio district, Ho Chi Minh City. Although the SQWI value increased from 35 (in 2018) to 82 (in 2019), the water environment was not considered polluted. However, the results also warn of the pollution level due to high SQWI coliform in Cau Den and Long Hoa in the rainy season.
    • Pollution of total petroleum hydrocarbon in coastal zone Ca Na, Ninh Thuan province

      Le, Trong Dung; Nguyen, Hong Thu; Le, Hung Phu; Phan, Hong Ngoc; Cao, Van Nguyen; Dao, Viet Ha (2021)
      Collection of Marine Research Works
      The paper presents the analysis results of total petroleum hydrocarbon (TPH) in the water and sediments of two surveys at 12 stations in the Ca Na sea area in Ninh Thuan province in April 2018 and December 2019. Water samples were extracted by liquid-liquid method with dichloromethane solvent, sediment samples extracted by Soxhlet method, and Dichlorometal. Analysis by gas chromatography with FID detector (GC-FID). The total hydrocarbon content is calculated from the carbon range C9 to C36. The results showed that the concentration of TPH in the water ranged from 1.2 to 32.3µg/l with an average of 11.9±6.2µg/l, nearshore stations in the north (Mui Dinh) have higher concentrations than in the south (Ca Na), the concentration in December 2019 was higher than in April 2018 at most stations. In the sediments, the average TPH content is 4.3µg/gdry, ranging from 1.7-11.0 µg/gdry, showing that the sediment here has not been contaminated with TPH.