Prospects for development of Vietnam underwater springs

Author(s):  
Yu.V. Kirichenko ◽  
Tran Thien Ngo Quy

The issues of the relevance of exploration and development of seabed deposits are considered. The article provides information on the history and composition of studies of solid mineral deposits carried out in the South China Sea by scientists of the Democratic Republic of Vietnam. The oceanographic and geological characteristics of the Pacific coast of Vietnam, its shelf and continental slope are given. The conditions that form placer deposits in the exclusive economic zone of Vietnam are given, and their brief description is given. Examples of various placers in the shelf zone, their features are given, and schematic diagrams of occurrence are given. The dependence of the littoral width on the height of the tidal wave and the angle of inclination of the shelf is analyzed. Proposals are given on the possibility of developing alluvial deposits in the littoral zone using dry drilling equipment, the advantages and disadvantages of this technology are stated. The features of the influence of climatic conditions of the Pacific coast of Vietnam on the use of hydromechanized technologies in the development of underwater placers are noted. Emphasis is placed on maintaining the ecological balance in the fields of development and the continuation of further research in the South China Sea.

2020 ◽  
Author(s):  
HN Le ◽  
N Muangmai ◽  
S Kheauthong ◽  
Z Sun ◽  
Giuseppe Zuccarello

© 2019 Japanese Society of Phycology Flattened Gracilaria species are widely distributed along the coasts of the South China Sea with more than 20 species recorded. Within the South China Sea, Gracilaria mammillaris has only been reported from Vietnam, but this species is likely restricted to the western Atlantic. This study aimed to reevaluate the taxonomic status of Vietnamese specimens of ‘G. mammillaris’ using combined morphological and molecular data. Our data clearly indicated that Vietnamese specimens were morphologically and genetically distinct from authentic G. mammillaris from the western Atlantic, and also other described flat Gracilaria species. We, therefore, propose that specimens from Vietnam originally identified as G. mammillaris be designated as a new species, Gracilaria phuquocensis sp. nov. Morphologically, G. phuquocensis can be distinguished from other flat Gracilaria species by its small thallus size, narrower blades, many medullary layers, abundant basal nutritive filaments within mature cystocarps, and tetrasporangial nemathecium. Our rbcL sequence analyses showed that the new species was sister to Gracilaria rhodymenioides from Thailand, and these two species formed a clade with cylindrical Gracilaria species. Our study contributes to clarification of the taxonomic status of misidentified specimens attributed to the flattened Gracilaria species in the South China Sea.


2020 ◽  
Author(s):  
HN Le ◽  
N Muangmai ◽  
S Kheauthong ◽  
Z Sun ◽  
Giuseppe Zuccarello

© 2019 Japanese Society of Phycology Flattened Gracilaria species are widely distributed along the coasts of the South China Sea with more than 20 species recorded. Within the South China Sea, Gracilaria mammillaris has only been reported from Vietnam, but this species is likely restricted to the western Atlantic. This study aimed to reevaluate the taxonomic status of Vietnamese specimens of ‘G. mammillaris’ using combined morphological and molecular data. Our data clearly indicated that Vietnamese specimens were morphologically and genetically distinct from authentic G. mammillaris from the western Atlantic, and also other described flat Gracilaria species. We, therefore, propose that specimens from Vietnam originally identified as G. mammillaris be designated as a new species, Gracilaria phuquocensis sp. nov. Morphologically, G. phuquocensis can be distinguished from other flat Gracilaria species by its small thallus size, narrower blades, many medullary layers, abundant basal nutritive filaments within mature cystocarps, and tetrasporangial nemathecium. Our rbcL sequence analyses showed that the new species was sister to Gracilaria rhodymenioides from Thailand, and these two species formed a clade with cylindrical Gracilaria species. Our study contributes to clarification of the taxonomic status of misidentified specimens attributed to the flattened Gracilaria species in the South China Sea.


2019 ◽  
Vol 32 (3) ◽  
pp. 685-700 ◽  
Author(s):  
Pengfei Tuo ◽  
Jin-Yi Yu ◽  
Jianyu Hu

This study finds that the correlation between El Niño–Southern Oscillation (ENSO) and the activity of mesoscale oceanic eddies in the South China Sea (SCS) changed around 2004. The mesoscale eddy number determined from satellite altimetry observations using a geometry of the velocity vector method was significantly and negatively correlated with the Niño-3.4 index before 2004, but the correlation weakened and became insignificant afterward. Further analyses reveal that the ENSO–eddy relation is controlled by two major wind stress forcing mechanisms: one directly related to ENSO and the other indirectly related to ENSO through its subtropical precursor—the Pacific meridional modes (PMMs). Both mechanisms induce wind stress curl variations over the SCS that link ENSO to SCS eddy activities. While the direct ENSO mechanism always induces a negative ENSO–eddy correlation through the Walker circulation, the indirect mechanism is dominated by the northern PMM (nPMM), resulting in a negative ENSO–eddy correlation before 2004, and by the southern PMM (sPMM) after 2004, resulting in a positive ENSO–eddy correlation. As a result, the direct and indirect mechanisms enhance each other to produce a significant ENSO–eddy relation before 2004, but they cancel each other out, resulting in a weak ENSO–eddy relation afterward. The relative strengths of the northern and southern PMMs are the key to determining the ENSO–eddy relation and may be related to a phase change of the interdecadal Pacific oscillation.


Zootaxa ◽  
2020 ◽  
Vol 4732 (2) ◽  
pp. 323-331
Author(s):  
VLADIMIR G. GAGARIN

Two nematode species isolated from sediments of the littoral zone of the South China Sea on the coast of Vietnam are described and illustrated. Microlaimus capitatus sp. n. is closely related to M. affinis Gerlach, 1958 and M. amphidius Kamran et al., 2009, but differs by having a thin, poorly developed pharyngostom, more posterior vulva and presence of terminal setae on the tail. The female of Dichromadora simplex Timm, 1961 is described and illustrated for the first time. 


2019 ◽  
Vol 38 (4) ◽  
pp. 1-11 ◽  
Author(s):  
Zexun Wei ◽  
Shujiang Li ◽  
R. Dwi Susanto ◽  
Yonggang Wang ◽  
Bin Fan ◽  
...  

Zootaxa ◽  
2020 ◽  
Vol 4730 (1) ◽  
pp. 1-61
Author(s):  
JAMES A. BLAKE

Eighteen species of Orbiniidae, 15 new to science, are reported from deep-sea habitats in the Pacific Ocean and the South China Sea. The collection includes specimens from continental slope and abyssal soft sediments as well as hydrothermal vent and methane seep sites. New collections of Califia calida Hartman, 1957, Naineris uncinata Hartman, 1957, and Phylo nudus (Moore, 1911) allow redescription and new distributional records of these species to be documented. Five species of Leitoscoloplos: L., cliffordi n. sp., L. gordaensis n sp., L. lunulus n. sp., L. sahlingi n. sp., and L. williamsae n. sp. are described together with a new species of Berkeleyia, B. lelievre n. sp., two new species of Scoloplos: S. californiensis n. sp. and S. sparsaciculus n. sp., and a new species of Leodamas, L. bathyalis n. sp. In addition, six new species of Orbiniella are described: O. abyssalis n. sp., O. eugeneruffi n. sp., O. grasslei n. sp., O. longilobata n. sp., O. rugosa n. sp., and O. tumida n. sp. 


Sign in / Sign up

Export Citation Format

Share Document