High level of local endemism under high risk of extinction: Systematics, evolution, autecology, population and conservation status of Tiger geckos (Goniurosaurus) in Vietnam

Tiger geckos of the genus Goniurosaurus currently consist of 24 species in Southeast and East Asia, all of which have been found in allopatry with a high level of local endemism. Five species are currently known from Vietnam, viz. G. araneus, G. catbaensis, G. huuliensis, G. lichtenfelderi and G. luii. Although new species of Goniurosaurus are still being discovered, the genus has become threatened by extinction through anthropogenic impacts. Unfortunately, once the thesis started, none of Goniurosaurus species were yet included in any wildlife protection laws, neither in China nor in Vietnam. In spite of the urgent requirement for protection, Goniurosaurus species have been omitted from the prioritization of conservation schemes due to a lack of biological background. In this study, I employed integrative methods of morphology, genetics, ecology, demography, and species distribution models in order to provide insights into the systematics, evolution, autecology, population status and threats of tiger geckos in Vietnam for conservation implications. Based on data collected during recent field work by our team, we expanded morphological descriptions of Vietnamese tiger geckos, evaluated variations among all Goniurosaurus species and provided an identification key. Our phylogenetic analyses showed that all recorded populations of Goniurosaurus from Vietnam are monophyletic with low intraspecific divergences (0 – 1.9 %), which are assigned to one of the four known species, namely G. catbaensis, G. huuliensis, G. lichtenfelderi and G. luii. Together with genetic data of remaining species from China and Japan, we evaluated the phylogeny of 23 species of Goniurosaurus. The analysis strongly supported the recognition of four monophyletic species groups (namely G. kuroiwae, G. lichtenfelderi, G. luii and G. yingdeensis). We further calibrated the divergence date of generic origin in the Eocene (approximately ~45.3 mya), and the diversification within four monophyletic groups began in the mid-Miocene ~13.4 – 7.7 mya and continued to at least the mid-Pliocene ~2 mya among species. The cladogenetic events of Goniurosaurus were ergo assumed relative to past orogeny processes following the vicariance pattern, adapted habitat segregation (e.g. karst and granite) and altitudinal transition. Given the Grinnellian niche evolution, the speciation among Goniurosaurus species was further explained with both climatic niche conservatism and divergence patterns. We studied the habitat preference of four Vietnamese tiger gecko species. The ecological analyses confirmed that three Goniurosaurus species (G. catbaensis, G. huuliensis and G. luii) are limestone karst-dwelling specialists, while the habitat preference of G. lichtenfelderi is significantly different, viz. adapted to granite-stream forest. Being aware of the importance of demographical information for species conservation efforts, population monitoring was carried out to estimate the population size and density of two Vietnamese Goniurosaurus species (namely, G. catbaensis and G. huuliensis). Consequently, their population size and density were found to be exceedingly small and negatively correlated to the increasing severity of human impacts. 3In this study, an extensive attempt was implemented to outline domestic and international trade activities in Goniurosaurus species. As a result, a large number of wild Goniurosaurus individuals from Vietnam and China have been over-harvested for international trade, although our records only reflected snapshots. Given potential impacts of climate change, we applied species distribution models (SDMs) to project the potential distribution of three Vietnamese Goniurosaurus species (namely, G. catbaensis, G. huuliensis and G. lichtenfelderi). Under climate change scenarios, their suitable habitats were predicted to shift towards higher latitudes, shrink significantly and even vanish in their entire distribution within the next decades. Furthermore, the increasing rate of habitat degradation and forest conversions dramatically imperils wild populations of Goniurosaurus species in Vietnam. Under severe human impacts, all species of Goniurosaurus from China and Vietnam were listed in CITES Appendix II, and Vietnamese species were assessed as globally threatened in the IUCN Red List and were protected by national laws as well. In this context, we identified priority areas – especially in protected areas, islands and transboundary regions – for conservation actions, and highly recommended the establishment of species and habitat conservation areas for tiger geckos in Vietnam. In conclusion, this study clarified issues related to the systematics and proved evolutionary hypotheses of geographical origin and relevant abiotic factors for the diversification of Goniurosaurus species and their allopatric distribution. Together with assessments of ecology, demography and anthropogenic threats, the thesis emphasized the urgent requirement of conservation actions. In this context, conservation programs and solutions were proposed to protect Goniurosaurus species in Vietnam and their habitats in the future

Batrachochytrium salamandrivorans is the predominant chytrid fungus in Vietnamese salamanders

The amphibian chytrid fungi, Batrachochytrium dendrobatidis (Bd) and B. salamandrivorans (Bsal), pose a major threat to amphibian biodiversity. Recent evidence suggests Southeast Asia as a potential cradle for both fungi, which likely resulted in widespread host-pathogen co-existence. We sampled 583 salamanders from 8 species across Vietnam in 55 locations for Bsal and Bd, determined scaled mass index as a proxy for fitness and collected environmental data. Bsal was found within 14 of the 55 habitats (2 of which it was detected in 2013), in 5 salamandrid species, with a prevalence of 2.92%. The globalized pandemic lineage of Bd was found within one pond on one species with a prevalence of 0.69%. Combined with a complete lack of correlation between infection and individual body condition and absence of indication of associated disease, this suggests low level pathogen endemism and Bsal and Bd co-existence with Vietnamese salamandrid populations. Bsal was more widespread than Bd, and occurs at temperatures higher than tolerated by the type strain, suggesting a wider thermal niche than currently known. Therefore, this study provides support for the hypothesis that these chytrid fungi may be endemic to Asia and that species within this region may act as a disease reservoir

Research on aerodynamics of a wing-in-surface-effect ship by theory and experiment

The paper presents the results of theoretical and experimental studies of the aerodynamic characteristics of a wing-in-surface-effect ship (WISES), which was made under coordination of the Institute of Mechanics, Vietnamese Academy of Science and Technology. The theoretical researches are carried out by the half analytical method and together by the linear and nonlinear vortex lattice methods. The experiment was conducted by the model on wind tunnel OTl of The Technical Institute of Air Force - Air Defense

A case study on trade in threatened Tiger Geckos (Goniurosaurus) in Vietnam including updated information on the abundance of the Endangered G. catbaensis

Tiger geckos of the genus Goniurosaurus are considered as a susceptible reptile group, due to their restricted distribution ranges, specialisation to specific microhabitats and generally low population densities. While still new species have been discovered recently, Goniurosaurus species are threatened by extinction through habitat loss and collection for the pet trade. Of the 19 described species, for only eight species, the conservation status has been assessed within the IUCN Red List between 2016 and 2018 and all have been classified in the threat categories VU (Vulnerable), EN (Endangered) and CR (Critically Endangered). Goniurosaurus spp. are popular in the international pet market at least since the 1990s and several species experienced local extirpations as a consequence of massive over-collection in the past. However, tiger geckos have not been paid much attention for conservation, amongst others, due to the lack of comprehensive knowledge on their conservation status and biology. This study provides an overview of international trade in Goniurosaurus based on available data from 1999 to 2018 in the U.S. as well as data from online surveys and interviews in Europe and Vietnam, with the main focus on species native to Vietnam. All five tiger gecko species known from Vietnam were found in the local trade as wild captures for the national and international market and / or in the U.S. and Europe for relatively higher prices. We found that entire trade chains are very long (including several transfers and dealers involved) and that keeping and transport happen under poor conditions. We herein provide updated information on the abundance of the Endangered Cat Ba Tiger Gecko, which was recently shown to not only occur at its type locality, Cat Ba Island, Hai Phong City, North Vietnam, but also to inhabit small offshore islands in the Ha Long Bay, Quang Ninh Province. While the wild effective population was found to be relatively stable on four islands in Ha Long Bay, consisting of about 124 and 129 individuals in July 2017 and April 2018, respectively, the abundance of other sub-populations, impacted by anthropogenic pressures were found to be very low (2–10 individuals). Based on our findings, we propose stringent conservation measures to more efficiently protect wild tiger gecko populations, such as the inclusion in the Governmental Decree in Vietnam, the assessment of remaining species in the IUCN Red List of Threatened Species and the inclusion in the Appendices of the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES)

Environmental Pollution of Heavy Metals in a Vietnamese Informal E-waste Processing Village

Inappropriate handlings of informal e-waste processing have increasingly become a global environmental and public health issue of concern. This study was conducted to quantify the concentrations of five heavy metals found in the environmental media at an exposed village and a reference village in Northern Vietnam. The correlations between a pair of the heavy metals found in a medium, and between a pair of the environmental media was found. The results showed that drinking water was safe for heavy metal exposure in both studied villages. However, at the exposed village, the levels of the heavy metals found in indoor soil were, in descending order, Pb (678.42 ± 846.11 mg kg-1) > Ni (148.77± 163.80 mg kg-1) > Cr (61.99 ± 42.50 mg kg-1) > As (7.62 ± 3.33 mg kg-1) > Cd (6.34 ± 12.39 mg kg-1). The levels of Pb, Cd, Cr, and Ni in indoor soil and surface dust in the exposed village were significantly higher than those in the reference village at p<0.001. The average concentrations of Pb, Cd, Cr, Ni and As in indoor soil were 3.57, 8.78, 1.90, 4.41, and 1.08 times, respectively, higher than those in outdoor soil at p<0.001. The levels of Pb and Cd found in indoor soil at the exposed village were 9.69 and 3.17 time, respectively, higher than the maximum allowable limits in Vietnam. Significant correlations between the pairs of the heavy metals in a medium and between the pair of the environmental media was found at the exposed village. This finding suggested that inappropriate activities conducted at an informal e-waste processing facility could be a major contributor to the heavy metal contaminations. This study highlighted the importance of release mitigation of a hazardous heavy metal from an informal e-waste processing facility to prevent its potential effects on human health

Review on membrane module configurations used for membrane distillation process

Nowadays, with the salient advantages of the seawater desalination process, membrane distillation (MD) technology has received increased interests to achieve desalination application. As a heat-based technology, by using the hydrophobic membrane, MD provides high efficiency in the desalination process of seawater, RO water and other solutes with high concentrations of dissolved solids. Besides, this is an alternative technology to significantly reduce the environmental impacts of traditional desalination technologies commonly used, such as distillation or reverse osmosis. In many factors affecting the desalination capacity of the membrane distillation system, membrane module configuration has a strong influence in evaluating the economic and technical efficiency of the technology. This review aims to assess the suitability of MD technology under different perspectives on the current types of membrane module configurations that include flat sheet, tubular, hollow fibre and spiral wound membranes. In addition, the evaluation of the advantages and disadvantages of the membrane module configurations will guide further studies to improve the shortcomings of existing MD technologies

New record and dietary ecology of an endangered amphibian species, Micryletta nigromaculata Poyarkov, Nguyen, Duong, Gorin & Yang, 2018, from Vietnam

The Black-spotted Paddy Frog (Micryletta nigromaculata) was recently discovered from northern Vietnam. Due to its restricted distribution in limestone karst forests and habitat degradation, the endemic species has been listed as “Endangered” in the IUCN Red List. However, knowledge about the natural history of this species is scarce, including data on its dietary ecology. Recent field surveys revealed new populations of M. nigromaculata occurring in Son La Province, northwestern Vietnam based on morphological analysis. Using the stomach-flushing method, we analyzed stomach contents of 45 individuals (21 males and 24 females) from a total of 52 captured frogs because stomachs of six males and one female (13.5%) were empty. The food spectrum of M. nigromaculata comprises 12 types with a total of 691 prey items (687 invertebrate items and four unidentified items), belonging to six insect orders, larvae and Araneae. Similar to other species of the family Microhylidae, M. nigromaculata is also identified as an ant (Formicidae) – termite (Rhinotermitidae) eating specialist with distinctly higher percentages of occurrence frequency (F = 65 %), number of prey items (N = 80 %), and importance (Ix = 75 %) than those of remaining types. The Simpson diversity index of 0.939 shows a high abundance of food prey in the wild, and the Evenness index of 0.536 suggests biased consumption of feeding selection for M. nigromaculata

Antibacterial Nanocomposites Based on Fe 3

For the vulcanized natural rubber (NR), incorporation of silver nanoparticles (AgNPs) into the NR matrix did not exhibit the bactericidal property against Escherichia coli (E. coli). However, incorporation of AgNPs into polyethylene (PE) matrix showed good antibacterial activities to both Gram-negative and Gram-positive bacteria. In the present work, NR/PE (85/15) blends have been prepared by melt blending with presence of compatibilizer in an internal mixer. To possess antibacterial property, AgNPs (5–10 nm) or Fe3O4–Ag hybrid nanoparticles (FAgNPs, 8 nm/16 nm) were added into PE matrix before its blending with NR component. The tensile test indicated that the presence of compatibilizer in NR/PE blend significantly enhanced the tensile strength and elongation at break (up to 35% and 38% increases, resp.). The antibacterial activity test was performed by monitoring of the bacterial lag-log growth phases with the presence of nanocomposites in the E. coli cell culture reactor. The antibacterial test showed that the presence of FAgNPs in NR/PE blend had a better antibacterial activity than that obtained with the lone AgNPs. Two similar reasons were proposed: (i) the faster Ag+ release rate from the Fe3O4–Ag hybrid nanoparticles due to the electron transfer from AgNP to Fe3O4 nanoparticle and (ii) the fact that the ionization of AgNPs in hybrid nanostructure might be accelerated by Fe3+ ions

HAEMAGGLUTINATION ACTIVITY OF THE EXTRACTS FROM SOME VIETNAM MARINE INVERTEBRATES

Aqueous extracts from 21 species of Vietnam marine invertebrates, including 11 bivalve and 10 gastropod species, were examined for haemagglutination activity using native and enzyme-treated different animal and human erythrocytes. The 8 bivalve and 10 gastropod species were found to have haemagglutinination activities toward at least one type of erythrocyte tested. A total of 86% of marine invertebrate species surveyed were active. Strong activity was detected in extracts from two bivalve species (Tridacna squamosa and Geloina coaxans) and three gastropod species (Tutufa rubeta, Pleuroploca trapezium and Tectus conus) with enzyme-treated rabbit, horse and human A, B, O erythrocytes. In a haemagglutination–inhibition test with various monosaccharides and glycoproteins, haemagglutination activities of two extracts from T. rubeta and P. trapezium had no affinity for any of the monosaccharides and glycoproteins tested, while activities of the extracts from T. squamosa and T. conus were strongly inhibited by porcine stomach mucin tested, suggesting the presence of lectins specific for O-glycans of these species. The activities of four marine invertebrate extracts were stable over a wide range ofpH and temperature. The haemagglutination activities of T. rubeta and P. trapezium extracts were independent of the presence of divalent cations, whereas the haemagglutination activity of extracts from T. squamosa and T. conus were slightly dependent on the presence of divalent cations. The results suggest that Vietnam marine invertebrates may be good sources of useful lectins for biochemical and biomedical applications

Synthesis and Characterization of Silver Nanoplates by a Seed-mediated Method

Silver nanoplates (SNPs) having different size were synthesized by a seed-mediated method. The seeds -silver nanoparticles with 4 – 6 nm diameters were synthesized first by reducing silver nitrate with sodium borohydride in the present of Trisodium Citrate and Hydrogen peroxide. Then these seeds were developed by continue reducing Ag$^+$ ions with various amount of L-Ascorbic acid to form SNPs. Our analysis showed that the concentratrion of L-Ascorbic acid, a secondary reducing agent, played an important role to form SNPs. In addition, the size and in-plane dipole plasmon resonance wavelenght of silver nanoplates were increased when the concentration of added silver nitrate increased. The characterization of SNPs were studied by UV-Vis, FE-SEM, EDS and TEM methods