Halong Bay Research Articles

식민지 베트남의 ‘열린’ 바다

Located on the C?m River, with access to the sea as well as connections to Ha N?i and other ports on the Red River, H?i Phong was formed in special situations such as independence movement. When the Tr?ng Sisters rebelled, Le Chan also directly led her troops to fight against the Chinese forces, causing them to suffer great losses, but the overall situation was unfavourable. At the two Battles of B?ch đ?ng River in 938 and in 1288 the Vietnamese forces defeated the Chinese invaders and put an end to Chinese imperial domination of the Vietnamese. It took place at the B?ch đ?ng River, near Halong Bay in northern Vietnam.BR H?i Phong has existed as a significant port from the XVth century, and was one of Vietnam’s principal trading centers. When Vietnam was invaded by the French, the city became France’s main naval base and trading port in Indochina. Since then, French colonialists speeded up urbanization process of H?i Phong city by building sea ports, river ports, warehouses; Ha N?i～H?i Phong railway, H?i Phong～Yunnan railway, some urban infrastructure etc. After that French, Chinese and Vietnamese ship building and repairing factories were established quickly. Industries, machinery, processing, chemistry were also expanded.BR While Indochinese exports and imports continued to grow in volume, there have been various social phenomena such as new settlers whose number was increasing. Especially, the Chinese immigrants played an important role in the economic development in H?i Phong. These social symptom had a tendency to stimulate certain conflicts between the overseas Chinese who were thought to cause some social problems, and the natives who fell prey to the colonial policy. The massacre of 17 August 1927 was done with the connivance of the colonial authorities. This kind of the French strategy would backfire and have a negative effect on the colonial policy in the modern port of H?i Phong.

Study on several biological characteristics affected on the biofilm formation capacity of the phenol-degrading yeast Trichosporon asahii B1 isolated from Ha Long, Quang Ninh

Several phenol-degrading and biofilm-forming yeast strains have been isolated from oil polluted sediment and water samples collected in Halong Bay, Quang Ninh. Amongst, QN-B1 strain with circle, convex, rough and white colony and 3-4 mm of diameter is considered as the best organism to degrade phenol and form biofilm. The yeast strains was then identified by ITS1-5.8rRNA-ITS2 sequencing analysis and showed homological coefficient of 99% with Trichosporon asahii. Based on morphological, bio-physical and bio-chemical characteristics, the strain was named as Trichosporon asahii QN-B1. It was signed in genbank as number KC139404. The influences of initial pH, NaCl concentrations and temperature on biofilm formation were investigated. As a result, the optimal biofilm formation conditions were pH from 3 to 7, NaCl of 1.5% and at 30oC. It also could grow in the minimum mineral salt medium supplemented with 200ppm phenol. Using optimal condition of biofilm formation, the QN-B1 could degrade up to 90% of phenol with the initial concentration of 200 ppm. These results showed potential application of biofilm forming yeasts in treatment of phenol and other aromatic compounds polluted in water in Vietnam.

A remarkable new Nilotonia species (Acari, Hydrachnidia, Anisitsiellidae) from percolating water of a cave in Cat Ba island in Halong Bay, Vietnam.

Both sexes of Nilotonia sketi sp. nov. are described from percolating water of a cave in Cat Ba island in Halong Bay, Vietnam. The IV-L-6 of the new species is characterized by a line of longer ventral setae, and presence of two longer distoventral setae. The systematic position of Nilotonia species attributed to the subgenera Dartiella K. Viets, 1929 and Dartonia K. Viets, 1929 are discussed. The latter subgenus is re-defined and Dartiella is proposed as its junior synonym. Two new subgenera, Gereckonia (type species: Nilotonia turcica Ozkan & Soysal, 1989 from Turkey) and Davetonia (type species: Nilotoniaperplexa Cook, 1967 from India) are erected.

The Geotourism View of the Topographic Landscape of Halong Bay, Vietnam

The Geotourism View of the Topographic Landscape of Halong Bay, Vietnam

Expanded description ofNeoechinorhynchus (Hebesoma) manubrianus(Acanthocephala: Neoechinorhynchidae) from marine fish in Halong Bay, Vietnam

Neoechinorhynchus manubrianus Amin, Ha & Ha, 2011 (Acanthocephala: Neoechinorhynchidae) (formerly Neoechinorhynchus manubriensis Amin, Ha & Ha, 2011), was recently described based on optical microscopy of four males and two females (none was gravid) from caroun croaker, Johnius carouna (Cuvier), flower croaker, Nibea albiflora (Richardson), and silver croaker, Pennabia argentata (Houttuyen) (Sciaenidae) in Halong Bay, Vietnam. Subsequently, many more specimens became available from N. albiflora that were studied using SEM. SEM studies showed many additional features that were not possible to discern with optical microscopy. These included the prominent angulation of the anterior trunk, the presence of (1) anterio-dorsal and (2) undulating mid-lateral fin-like protrusions of the body wall, uniquely shaped eggs as well as details of trunk micropores, proboscis, bursa, and female gonopore. Microscopical examination of eggs from the new collection demonstrated the presence of polar prolongation of fertilization membrane which places N. manubriensis in the subgenus Hebesoma. The features of trunk angulation, trunk fins, and egg morphology further distinguish N. manubriensis from all other species of Neoechinorhynchus Stiles and Hassall, 1905 from Vietnam or from any where else in the world.

On four species of echinorhynchid acanthocephalans from marine fish in Halong Bay, Vietnam, including the description of three new species and a key to the species of Gorgorhynchus

Four species of echinorhynchid acanthocephalans were collected from marine fish off Cat Ba Island, Halong Bay, Gulf of Tonkin, Vietnam, in the spring of 2009. Acanthocephalus halongensis n. sp. (Echinorhynchidae) from the redtail scad, Decapterus kurroides Bleeker 1855 (Carangidae), has a unique proboscis armature with a spiniform basal hook with lateral root and an incomplete receptacle wall posteriorly. Gorgorhynchus tonkinensis n. sp. (Rhadinorhynchidae) also from D. kurroides, has long, slender, winding lemnisci, many epidermal nuclei, and a narrow anterior trunk with a shoulder armed with 20 circles of tightly packed spines, the posterior four circles of which have abruptly larger spines than those in the anterior circles. Neorhadinorhynchus atypicalis n. sp. (Cavisomidae) from the rabbitfish, Siganus fuscescens (Houttuyn 1782) (Siganidae), has the largest number of proboscis hooks per row, testes wider than long, and four clustered cement glands. Micracanthorhynchica kuwaitensis Amin and Sey 1996 (Rhadinorhynchidae) from the spottail needlefish Strongylura strongylura (van Hasselt 1823) (Belonidae) was similar to specimens originally described from the Arabian Gulf off the Kuwaiti coast. These acanthocephalans were collected in small numbers but stood out as uniquely and considerably different from their closest relatives to warrant their reporting. All species of acanthocephalans and their host and geographic distribution are described, and a key to the species of Gorgorhynchus is provided.

First report of Neoechinorhynchus (Acanthocephala: Neoechinorhynchidae) from marine fish of the eastern seaboard of Vietnam, with the description of six new species.

The occurrence of acanthocephalans of the genus Neoechinorhynchus Stiles and Hassall, 1905 in Vietnamese waters is reported for the first time. Six new species are described from seven species of marine fish of the families Belonidae, Clupeidae, Megalopidae, Mugilidae, and Sciaenidae, collected in Halong Bay of the eastern seaboard of Vietnam in 2008 and 2009. These are Neoechinorhynchus (Neoechinorhynchus) plaquensis n. sp. characterized by dermal plaques covering the entire trunk; Neoechinorhynchus manubriensis n. sp. with very long anterior proboscis hooks having roots with prominent anterior manubria and very small and equal middle and posterior hooks, two pseudoretractors in the receptacle, simple vagina, and terminal gonopore; Neoechinorhynchus pennahia n. sp. with equal anterior and middle proboscis and somewhat smaller posterior hooks, and terminal female gonopore; Neoechinorhynchus ampullata with many giant nuclei in the body wall and lemnisci and a parareceptacle structure complex which includes pumping ampullas reported for the first time; Neoechinorhynchus (Neoechinorhynchus) longinucleatus n. sp. with very long giant nuclei in the Lemnisci, anteriorly twisted vagina, and subterminal female gonopore. Neoechinorhynchus (Neoechinorhynchus) ascus n. sp. is the second species of Neoechinorhynchus found with the parareceptacle structure/ampulla complex. Neoechinorhynchus (Neoechinorhynchus) johnii Yamaguti, 1929 of Bilqees, 1972 is not N. johnii because of proboscis armature and other discrepancies with the Yamaguti material. Notes on host distribution and feeding habits are also included.

Description of Heterosentis holospinus n. sp. (Acanthocephala: Arhythmacanthidae) from the Striped Eel Catfish, Plotosus lineatus, in Halong Bay, Vietnam, with a Key to Species of Heterosentis and Reconsideration of the Subfamilies of Arhythmacanthidae

Abstract Heterosentis holospinus n. sp. is 1 of 11 species of acanthocephalans collected from 13 species of marine fish in Halong Bay, Vietnam, in 2008 and 2009. The striped eel catfish, Plotosus lineatus (Thunberg, 1787), harbored a large number of individuals of the new species. Species of Heterosentis Van Cleave, 1931, are characterized by having 2 or 3 types of proboscis hooks in 10–14 rows, and trunk spines. Of the 15 known species of Heterosentis (including the new species), H. holospinus is distinguished by having a trunk entirely covered with spines and an anterior trunk cone free of spines. Only Heterosentis overstreeti Schmidt and Paperna, 1978, has a trunk that is also entirely covered with spines; it, however, differs from H. holospinus by lacking an anterior trunk cone but having 4 giant nucleated muscle cells in the anterior trunk, and 2 basal spines per proboscis hook row. Heterosentis holospinus has no such muscle cells, and the proboscis contains 3–4 spines per row. Only 2 other species o...

Description of two new species of Rhadinorhynchus (Acanthocephala, Rhadinorhynchidae) from marine fish in Halong Bay, Vietnam, with a key to species

AbstractTwo rhadinorhynchid species of acanthocephalans, Rhadinorhynchus dorsoventrospinosus sp. nov. and Rhadinorhynchus laterospinosus sp. nov. are described from the redtail scad, Decapterus kurroides Bleeker, and the trigger fish Balistes sp., respectively. The hosts were collected off Cat Ba Island, Halong Bay, Gulf of Tonkin, Vietnam in May, 2009. This brings the total number of species of Rhadinorhynchus Lühe, 1911 to 38. Specimens of the first species are characterized by having 11–12 proboscis hook rows with 30–31 hooks each, large dorsal and ventral spines in the posterior field of trunk spines, large eggs (100 × 20), and subterminal gonopore in both males and females. It is further characterized by many prominent fragmented nuclei in the body wall. The 1 female of the second species has 18 proboscis hook rows with 24 hooks each, smaller eggs (62 × 17), lateral trunk spines connecting those in the anterior and the posterior fields, and subterminal female gonopore. Notes on the genus Rhadinorhynchus, lists of the invalid and valid species, and a key to species are provided. Raorhynchus Tripathi, 1959 is proposed to be a junior synonym of Rhadinorhynchus pending a revision of the species of Raorhynchus.

Examples of mathematical modelling of long term general corrosion of structural steels in sea water

Recent progress has been made in developing a mathematical and probabilistic model for general corrosion of structural steels exposed to sea water immersion corrosion. It is based on corrosion science principles, with early corrosion controlled by oxygen concentration limitations that eventually evolve to anaerobic bacterial controlled corrosion behaviour. The model has been calibrated to extensive literature data and original field tests. Herein, three different sets of corrosion field data, for Halong Bay in Vietnam, for an offshore oil platform site and for three coastal sites along the China coast are examined for compatibility with the model. It is shown that all the data are consistent with the model provided allowance is made for the season of the first immersion, the effect of sea water velocity and the possibility of nutrient pollution. In its most general form, the model is probabilistic to allow for natural variability owing to unrecorded (and perhaps unrecordable) influences. The data considered herein are sufficient for comparing with the expected value of the model but not for considering statistical variability. Finally, the model provides plausible explanations for differences in observed corrosion at different sites, considered by others to be due to the action of hard marine fouling.

Growth and population dynamics during early stages of the mangrove Kandelia candel in Halong Bay, North Viet Nam

Quantifying the dynamics of the early stages in the life cycle of mangroves is essential to predict the distribution, species composition and structure of mangrove forests, and their maintenance and recovery from perturbations. The growth and population dynamics of two stands of the mangrove Kandelia candel in Halong Bay (Viet Nam) were examined for 1 year. Growth was highly seasonal, with high growth rates and fast internode formation in the summer, dropping to extremely low growth during January–February, the coldest and driest months in the year. In addition, growth and internode formation rates showed important inter-annual variability during the last decade. The complete reproductive period required 7–8 months. Flower initiation was maximal in June and peak propagule maturity occurred in December–January. Only one mature propagule developed for every 67 and 127 inflorescence buds formed at Site 1 and Site 2, respectively. Kandelia candel propagules begun to sink 10 days after being released, and after 18 days all propagules had negative buoyancy. The propagules developed roots within 19–68 days, depending on whether they were held on the water or sediment, and were capable of long range dispersal, for 15–20% of them dispersed more than 100 m within 1 day. The median age of K. candel plants ranged between 8.7 and 5.6 years, with a density of 1900 and 470 plants ha −1, in Sites 1 and 2. Plant mortality was high, with 64 and 74% of the plants surviving after a year at Sites 1 and 2. Life expectancy (i.e. median age-at-death) of only 2.2 and 2.7 years at Sites 1 and 2, respectively, indicates that mortality of young K. candel plants was specially high. Recruitment occurred in early spring, and did not suffice to balance the mortality within the annual period examined. These results suggest that the K. candel stands in Halong Bay might be maintained by a few years of high recruitment which would compensate for generally high mortality rates.

Persistent organochlorine pesticides and polychlorinated biphenyls in some agricultural and industrial areas in Northern Vietnam

Organochlorine pesticide and polychlorinated biphenyl residues were determined in soils and surface sediments collected from Hanoi City, Viettri City and Halong Bay, which are representative of industrial and agricultural areas in northern Vietnam. Polychlorinated biphenyls (PCBs) and organochlorine insecticides such as DDT and its metabolites (DDTs) and lindane were detected in all samples analyzed, indicating the widespread contamination by these compounds in the environment of the north of Vietnam. Concentrations of DDTs and lindane were found to be highest in sediments from Halong Bay, followed by those in Viettri and Hanoi. PCB residues ranged from 0.64 ng g–1 120 ng g–1 (dry weight basis) in sediments and these levels were generally higher than those in soil samples. In general, higher concentrations of pesticides and PCBs were recorded in Halong Bay, suggesting the local sources in this area, probably from mining activities. High accumulation of DDTs in soils, sediments and biotafrom north to south Vietnam indicates that the recent input of DDT is still occurring throughout the country.

Influence of tectonics and neotectonics on the morphogenesis of the peak karst of Halong Bay, Vietnam

In northeast Vietnam, the karst of Halong Bay is characterized by very active neotectonics. The directional distribution of fracturing of the calcareous rocks is characterized by the influence of two major fault zones: the Red River fault zone (N140) and the Tan-Lu fault zone (N050). Karst development was favoured by intense fracturing, according to these two major directions, and reactived during recent tectonics by a compressional regime with σ1 N070, followed by an extensional regimes with σ1 near to EW that led to significant vertical movement. These tectonics, coupled with intense erosion, led to genesis and evolution of the spectacular morphology of this peak karst. © Elsevier, Paris

Influence of tectonics and neotectonics on the morphogenesis of the peak karst of Halong Bay, Vietnam

In northeast Vietnam, the karst of Halong Bay is characterized by very active neotectonics. The directional distribution of fracturing of the calcareous rocks is characterized by the influence of two major fault zones: the Red River fault zone (N140) and the Tan-Lu fault zone (N050). Karst development was favoured by intense fracturing, according to these two major directions, and reactived during recent tectonics by a compressional regime with σ1 N070, followed by an extensional regimes with σ1 near to EW that led to significant vertical movement. These tectonics, coupled with intense erosion, led to genesis and evolution of the spectacular morphology of this peak karst.