http://tvhdh.vnio.org.vn:8080/dspace/handle/123456789/18689 2026-08-06T12:32:10Z 2026-08-06T12:32:10Z Nguyen, Tuong Vi Phan, Minh Thu Le, Thi Thu Thao http://tvhdh.vnio.org.vn:8080/dspace/handle/123456789/21809 2026-08-06T08:53:31Z 2025-01-01T00:00:00Z

Title: Fish Assemblage Structure and Biodiversity in the Han and Cu De Rivers, Central Vietnam Authors: Nguyen, Tuong Vi; Phan, Minh Thu; Le, Thi Thu Thao Abstract: Estuarine ecosystems are among the most biodiverse yet increasingly threatened environments worldwide, particularly in tropical coastal regions where river and marine systems interact. This study investigated the structure, species composition, and seasonal variation of fish assemblages in the Han and Cu De Rivers in Da Nang City, central Vietnam. Field surveys were conducted during the rainy season (September–December 2024) and dry season (March–June 2025) at major fish landing sites and aquatic product collection points along the two river basins. A total of 957 specimens were collected and analyzed using standard morphological taxonomy, and community patterns were analyzed using Bray–Curtis similarity and Principal Component Analysis (PCA). Overall, 166 fish species belonging to 122 genera, 64 families, and 21 orders were recorded. Species richness differed between rivers, with 109 species in the Han River and 99 in the Cu De River, and only 42 shared species, indicating clear spatial differentiation. The Han River assemblage was dominated by estuarine and marine-associated taxa (e.g., Acanthuriformes and Carangiformes), whereas the Cu De River was characterized by freshwater taxa, particularly Cypriniformes (28.3%). Seasonal variation was pronounced, with 121 species recorded in the dry season compared to 75 in the rainy season. These findings demonstrate that the study area functions as an estuarine transition zone with strong environmental gradients shaping fish communities. The results provide essential baseline data for biodiversity conservation and fisheries management, while highlighting the importance of hydrological connectivity and seasonal dynamics in coastal river ecosystems.

2025-01-01T00:00:00Z Tuapetel, Friesland Hukubun, Ronald D. Apituley, Yolanda M.T.N. Tran, Cong Thinh Rauf, Syahril A. http://tvhdh.vnio.org.vn:8080/dspace/handle/123456789/21808 2026-08-06T08:52:27Z 2025-01-01T00:00:00Z

Title: Utilization and Management Implications of Bale-Bale Fishing Gear for Flying Fish Eggs (Exocoetidae) Authors: Tuapetel, Friesland; Hukubun, Ronald D.; Apituley, Yolanda M.T.N.; Tran, Cong Thinh; Rauf, Syahril A. Abstract: Flying fish (Exocoetidae) represent an important marine resource inthe Aru Islands, Eastern Indonesia, where their eggs have long been harvestedusing traditional bale-bale gear. However, recent increases in exploitation byandon fishers from Sulawesi have placed growing ecological strain on theresource and raised the risk of social tensions. This study investigates thedynamics of the flying fish egg fishery, evolving harvesting practices, and themanagement challenges associated with bale-bale use. Data were gatheredthrough field observations, structured interviews (2021–2023), participatorymapping, and policy review. The results show that 80% of the fishers aremigrants who operate between 2 and 200 nautical miles offshore, using gear thatranges from simple rafts to double-deck configurations. The overlap of fishingzones between local and andon fishers has intensified competition, leading to asignificant reduction in egg catch. Furthermore, centralized fisheries governancehas limited the effectiveness of local enforcement. Unregulated harvesting posesa serious threat to recruitment in flying fish populations, drawing parallels tochallenges observed in lobster seed collection. To mitigate these risks, the studyrecommends standardizing gear, restricting bale-bale use to a maximum of 85units per vessel, prohibiting double-deck rafts, enforcing stricter licensing andquota systems for migrant fleets, and enhancing coordination between differentlevels of government. A collaborative management framework rooted inscientific data is vital for safeguarding the long-term sustainability of the flyingfish egg fishery in Maluku waters.

2025-01-01T00:00:00Z Le, Hung Phu Pham, Hong Ngoc Le, Trong Dung Vo, Tran Tuan Linh Tran, Van Binh Ho, Van The http://tvhdh.vnio.org.vn:8080/dspace/handle/123456789/21807 2026-08-06T08:52:53Z 2025-01-01T00:00:00Z

Title: Geo-chemical fractionations of phosphorus in sediments of Thuy Trieu lagoon and Cam Ranh Bay, Vietnam Authors: Le, Hung Phu; Pham, Hong Ngoc; Le, Trong Dung; Vo, Tran Tuan Linh; Tran, Van Binh; Ho, Van The Abstract: The geochemical fractions of phosphorus (P) and its bioavailability in sediments of Thuy Trieu Lagoon and Cam Ranh Bay were investigated. Twenty-four surface sediment samples were collected in the dry season (Jun 2024) and the rainy season (Oct 2024). A sequential extraction procedure was applied to identify the phosphorus (P) fractions in sediments, including Exchangeable P (Ex-P), iron-bound P (Fe-P), aluminum-bound P (Al-P), calcium-bound P (Ca-P), and residual P (Res-P). Total P (TP) ranged from 214.9 to 2365.2 μg·g¡1 , and the Ca-P fraction was the dominant chemical form in sediments. Based on the results of Pearson correlation and principal component analysis, this study suggests that the terrestrial organic matter was the main source for shaping the distribution of P fractions in sediments. Meanwhile, the Ca-P fraction was likely formed through co-precipitation with calcite and other minerals in the sediments. The bioavailable P fraction constituted a small proportion of the total sedimentary P, accounting for 7.6—45.5 % in sediments of Cam Ranh Bay.

2025-01-01T00:00:00Z Bui, Minh Quan Ngo, Thi Kim Chi Bui, Vinh Hau Nguyen, Dac ve Jiang, Binbin http://tvhdh.vnio.org.vn:8080/dspace/handle/123456789/21806 2026-08-06T08:54:42Z 2026-01-01T00:00:00Z

Title: Satellite Data and Applying the DSAS Tool to Shoreline Change Assessment of the Mekong Delta Authors: Bui, Minh Quan; Ngo, Thi Kim Chi; Bui, Vinh Hau; Nguyen, Dac ve; Jiang, Binbin Abstract: The Mekong Delta is the third-largest delta in the world, with a large population, a significant food production area in Vietnam and home to large-scale biodiversity, is seriously affected by erosion - accretion of the coast, land subsidence. Several dams have been built upstream of the delta (Manwan, Nuozhadu…), and large-scale commercial sand mining in the river and delta channels, along with subsidence caused by groundwater extraction, are the causes of sediment decline in the Mekong Delta. This affects the daily lives of more than 21 million people. Using high-resolution satellite imagery (Landsat) for the period 1989-2020, this paper assesses erosion-accretion rates at the Mekong estuary to Ca Mau cape. Extracting the shoreline using the Normalized Difference Vegetation Index used to measure vegetation change and the Digital Shoreline Analysis System used to analyze changes in the shoreline. The results show that the Mekong estuary is having an alternating process of erosion-accretion, the balance of erosion-accretion tends to imbalance with dominant accretion. The Mekong estuary area, including the Tieu, Dai, Ba Lai, Ham Luong, Co Chien, Cung Hau, Dinh An and Tran De mouths, experiences erosion and accretion ranging from 1.37 to 120.98 m/yr and 74.94 to 117.06 m/yr, respectively. From My Thanh mouth to Ca Mau Cape, with erosion ranging from 66.07 to 115.5 m/yr and accretion from 29.67 to 91.06 m/yr, respectively. Our research emphasizes the fragility of the Mekong Delta coastline and underscores the critical role of remote sensing imagery in effective shoreline management.

2026-01-01T00:00:00Z Vu, T. Luong Nguyen, T. M. Huyen Hoang, P. Hiep Phung, T. Linh Nguyen, V. Sang Nguyen, V. N. Thanh Nghiem, T. H. Liem Do, M. Hao Nguyen, Q. Mai http://tvhdh.vnio.org.vn:8080/dspace/handle/123456789/21805 2026-08-06T08:51:59Z 2026-01-01T00:00:00Z

Title: Metagenomic analysis of lichen-like samples correlated to the mortality of cultured shrimp in aquaculture ponds in Vietnam Authors: Vu, T. Luong; Nguyen, T. M. Huyen; Hoang, P. Hiep; Phung, T. Linh; Nguyen, V. Sang; Nguyen, V. N. Thanh; Nghiem, T. H. Liem; Do, M. Hao; Nguyen, Q. Mai Abstract: Farmed shrimp, especially in aquaculture ponds in mainland, faced many risks due to disease and the stunted growth in Vietnam. For easy solving those problems shrimp farmers could use a lot of antibiotics, leading to antibiotic residues accumulating in the shrimp and creating antibiotic resistance in the surrounding organisms and environment. This report focused on analyzing of a fast-growing lichen-like species collected from shrimp farms in the Northern (M01) and Southern (NM1E2) region of Vietnam with a same symptom of stunted growth, respectively. Using shotgun metagenomics and bioinformatics analysis, microorganism community of lichen-like samples were identified. The results showed that Pseudomonas, Halomonas, Aeromonas, Vibrio, Shewanella, and Moraxella were the main bacterial genera contribute to the samples and haft of them (Vibrio, Shewanella, and Moraxella) could be potential pathogenic bacteria. The fungal analysis showed that both samples were colonized with Fusarium oxysporum and Fusarium graminearum, the fungus associated with plant diseases but increasingly implicated in infectious diseases in aquatic animals. The prevalence of other opportunistic fungi such as Aspergillus fumigatus also suggested that they could play a larger role in deteriorating shrimp health than originally thought. Our results are preliminary evaluation for the potential influence of the lichen-like organism in shrimp farm. The results suggest targeted environmental management and improved biosecurity measures to mitigate disease risks and enhance shrimp farm sustainability.

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