http://tvhdh.vnio.org.vn:8080/dspace/handle/123456789/19538 Fri, 23 Oct 2026 06:34:22 GMT 2026-10-23T06:34:22Z http://tvhdh.vnio.org.vn:8080/dspace/handle/123456789/21898 Title: Bilayer Zn-primer/Cu2O-topcoat ethyl silicate coating: a promising approach for combined marine corrosion and fouling resistance. Authors: Nguyen, Hoang; Truong, Anh Khoa; Le, Thi Nhung; Phan, Minh Phuong; Tran, Van Huynh; Khanh, Minh Chau; Nguyen, Tran Duy Nguyen Abstract: Protecting marine metallic structures requires coatings that provide both corrosion resistance and antifouling. This research investigated multifunctional ethyl silicate coatings combining zinc (Zn) and copper(I) oxide (Cu2O). We compared four systems: Zn-only, Cu2O-only, a single-layer Zn/Cu composite, and a bilayer Zn+Cu structure (Zn primer/Cu2O topcoat). Comprehensive evaluations included electrochemical corrosion behavior (DC polarization, 60-day EIS in 3.5 wt% NaCl), ion release kinetics, and long-term antifouling efficacy via 12-month natural marine exposure. Results revealed distinct performance profiles. The Zn coating provided excellent short-term corrosion protection but failed antifouling tests. Conversely, the Cu2O coating showed good initial antifouling via effective Cu release (~ 12–14 µg/cm2.day) but had poor corrosion resistance. The composite Zn/Cu coating exhibited intermediate properties. Significantly, the bilayer Zn+Cu system demonstrated the most favorable synergy, offering the best long-term corrosion resistance (highest impedance via EIS after 60 days), superior adhesion, sustained effective copper release (3.41 µg/cm2.day), and outstanding antifouling performance over 12 months. This study underscores the decisive role of coating architecture, identifying the bilayer Zn+Cu structure as a highly promising configuration for developing durable, multifunctional protective coatings for maritime applications. Thu, 01 Jan 2026 00:00:00 GMT http://tvhdh.vnio.org.vn:8080/dspace/handle/123456789/21898 2026-01-01T00:00:00Z http://tvhdh.vnio.org.vn:8080/dspace/handle/123456789/21897 Title: First record of strict snake eels, Xyrias revulsus Jordan & Snyder, 1901 (Anguilliformes: Ophichthidae), from Vietnamese waters. Authors: Vo, Van Quang; Le, Thi Thu Thao; Tran, Cong Thinh; Bui, Quang Nghi; Huans, Ching Ho Abstract: This paper presents the first record of the strict snake eel, Xyrias revulsus (Jordan & Snyder, 1901), from Vietnamese waters. Eleven specimens were collected at a local fishing port in northern Nha Trang. Xyriasrevulsusis distinguished from its congeners by a combination of the characters: a tail length shorter than the head and trunk (tail length 2.1–2.2 in TL; head length 8.6–9.8 in TL), an acute and short snout (6.0–7.6 in HL), and elongate jaws (upper jaw 2.4–2.5 in HL). The dorsal fin origin is well behind the pectoral fin tip, andthe pectoral fin is moderately developed. Fresh coloration is pale brown with dark brown spots on the dorsal surface above the lateral midline, fading to pale on the ventral surface. The teeth are sharp, needle-like, and slightly recurved on the jaws and vomer. The vertebral count is 17–18 predorsal, 79–81 preanal, and 162–164 total vertebrae (n = 2). This paper provides morphological data, a detailed description, and photographs of the species, thereby extending its distributional range. Thu, 01 Jan 2026 00:00:00 GMT http://tvhdh.vnio.org.vn:8080/dspace/handle/123456789/21897 2026-01-01T00:00:00Z http://tvhdh.vnio.org.vn:8080/dspace/handle/123456789/21895 Title: Cumulative impact from disturbances drives hard coral loss and Chaetodon butterflyfish decline in Nha Trang Bay Marine Protected Area, Vietnam. Authors: Nguyen, Van Long; Thai, Minh Quang; Mai, Xuan Dat; Nguyen, Le Thao My; Hoang, Xuan Ben; Manuel, Gonzalez-Rivero Abstract: Loss of live hard coral cover often drives declines in reef fish abundance, particularly among obligate corallivores such as butterflyfishes (Family Chaetodontidae). In this study, we investigated the variations in hard coral cover and Chaetodonbutterflyfish densities within the Nha Trang Bay Marine Protected Area (MPA), Vietnam, spanning nearly two decades (2005–2023). We monitored hard coral cover and butterflyfish densities at 5-year intervals from 2005 to 2015, then increased the monitoring frequency thereafter, and found that live hard coral cover plummeted by 25.8% across the entire study period. This habitat degradation directly mirrored changes in the butterflyfish assemblages. Between 2005 and 2018, both post-recruit (1.1–5.0 individuals/100 m²) and recruit (0.1–1.6 individuals/100 m²) densities remained stable. However, both cohorts suffered sharp declines through 2023. We attribute this collapse to cumulative acute disturbances, including two major typhoons (Damrey in November 2017 and Rai in December 2021), a mass coral bleaching event, and a crown-of-thorns starfish outbreak in 2019. Crucially, we detected no signs of coral or fish recovery following these impacts, even within the strictly protected core zones (NWMU and SWMU) of Mun Island. Thu, 01 Jan 2026 00:00:00 GMT http://tvhdh.vnio.org.vn:8080/dspace/handle/123456789/21895 2026-01-01T00:00:00Z http://tvhdh.vnio.org.vn:8080/dspace/handle/123456789/21894 Title: Species diversity, taxon structure and distribution of the macroalgae in Con Co Special Administrative Region, Vietnam. Authors: Do, Thi Thanh Trung; Nguyen, Thi Mai Anh; Tran, Khuong Canh; Le, Van Phuoc; Dam, Duc Tien; Christophe, Vieira; Le, Tat Thanh; Nguyen, Dinh Tu Abstract: This study presents the results of seaweed investigations conducted at four transects in the Con Co Special Administrative Region from 1994 to 2025. A total of 101 macroalgal species were recorded, belonging to four phyla. Among these, Cyanophyta comprised 5 species (4.9%), Rhodophyta 40 species (39.6%), Ochrophyta (Phaeophyta) 36 species (35.6%), and Chlorophyta 20 species (20.5%). We classified these species into 23 orders, 38 families, and 49 genera, indicating a mixed algal flora. Species richness across the studied transects ranged from 51 species (transect I) to 76 species (transect IV), with an average of 63.8 species per transect. The similarity coefficient among transects varied from 52.63 (between transects I and IV) to 78.14 (between transects IV and V), with an average value of 67.64, reflecting a moderate to high degree of similarity in species composition. In terms of ecological distribution, 20 species (19.8%) were found exclusively in the intertidal zone, 44 species (43.6%) occurred only in the subtidal zone, and 37 species (36.6%) were distributed across both zones. Most species were concentrated from the lower intertidal zone to the upper subtidal zone, highlighting this transitional area as a key habitat for macroalgal diversity. Taxonomic structure varied considerably among phyla. Rhodophyta exhibited the highest diversity, with 12 orders, 17 families, 23 genera, and 40 species, while Cyanophyta showed the lowest diversity. On average, each phylum included 5.75 orders, each order contained 9.5 families, and each phylum comprised approximately 12.25 genera and 25.25 species. Several genera contained only a single species, whereas others, such as Sargassum (10 species), Lobophora (9 species), and Caulerpa (5 species), showed higher species richness. Similarly, some families included only one genus, while others contained multiple genera. The distribution of the 23 recorded orders was uneven among the four phyla, with Rhodophyta accounting for the highest proportion (52.1%). Notably, several recorded species belong to economically important genera such as Porphyra, Grateloupia, and Sargassum, which have applications in food, pharmaceuticals, and cosmetics. Thu, 01 Jan 2026 00:00:00 GMT http://tvhdh.vnio.org.vn:8080/dspace/handle/123456789/21894 2026-01-01T00:00:00Z http://tvhdh.vnio.org.vn:8080/dspace/handle/123456789/21893 Title: Rainfall variation and its correlation with El Niño‑Southern Oscillation (ENSO) in Ho Chi Minh City. Authors: Nguyen, Minh Hai; Vu, Duy Vinh; Nikita, Sandalyuk; Alexander, Osadchiev Abstract: This study analyzes rainfall variability and its links to ENSO phenomena in Ho Chi Minh City using data from Nha Be station (1999–2024). Results show that rainfall is highly concentrated in the wet season (May-November), with 84% of the annual total, while the remaining 16% occurs during the dry season (December-April). Despite high monthly and interannual fluctuations, annual totals remain relatively stable (mean 1683 mm, CV = 20.7%). Trend analysis using the Mann-Kendall test and Sen’s Slope indicates no significant trend, except for an increasing trend in September (6.2 cm/year, P = 0.052). Empirical Mode Decomposition (EMD) reveals multi-scale rainfall oscillations. IMF6-IMF8, corresponding to 1.7–6.5 years, are linked to ENSO signals. A composite IMF678 shows a significant inverse correlation with the Oceanic Niño Index (R = -0.361, lag = 7 months), indicating that El Niño reduces rainfall by 81.6 mm, while La Niña increases it by 51.8 mm. Extreme rainfall indices R25mm and R99p show strong interannual variability and tend to increase during La Niña years (1999–2000, 2010–2012, 2017–2018) and decrease during El Niño years (2002–2003, 2014–2015). However, some exceptions (2009–2010) indicate additional influences from regional factors. Thu, 01 Jan 2026 00:00:00 GMT http://tvhdh.vnio.org.vn:8080/dspace/handle/123456789/21893 2026-01-01T00:00:00Z