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Collection of Marine Research Works, Vol. XIV, 2005

Publish year: 2005
Category: COLLECTION OF MARINE RESEARCH WORKS

Contents

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9.
Doan Nhu Hai, Nguyen Ngoc Lam, Nguyen Thi Mai Anh, Ho Van ThePhytoplankton in Lang Co lagoon, Central Vietnam.
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Nguyen Van Luc, Nguyen Tac An, Nguyen Phi Uy Vu, Le Thi Thu Thao, Tran Van Lang, Nguyen Thi LienFish resources and their utilization in De Gi lagoon – Binh Dinh province.
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14.
15.
Vo Si Tuan, Truong Si Ky, Ha Le Thi Loc, Hua Thai Tuyen, Nguyen Thi Kim BichTrial for culturing commercial Green Mussel Perna viridis (Linaeus, 1758) in Nha Phu lagoon – Khanh Hoa.
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17.
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THE MIDDLE AND LONG-TERM VARIATION OF WATER TEMPERATURE AND SALINITY IN THE OPEN REGION OF THE EAST SEA
 Vo Van Lanh, Nguyen Van Tuan
Institute of Oceanography (Nha Trang)
 
Abstract:
   The paper reflects the characteristics of middle (diurnal and synoptic) and long-term (annual and interannual) variation of water temperature and salinity in the open region of the East Sea obtained on the basis of analyzing the observation data. The considered parametres are the extremal values of water temperature and salinity and magnitudes of their variation.
The most interesting study results are as follow:
-The magnitudes of the middle and long - term variations of hydrological elements (water temperature, salinity and also current) reach maximum values not at the sea surface, but in seasonal thermocline (30 -100m).
-The sea surface temperature has tendency to be increased continuously in recent decades (about 10C during 1982-1999).
-The periods of interannual variation of water temperature are very different depending on the specialities of the climate and weather changes.
-The periods of synoptic hydrological variations are from 2-3 to 6-7 days.
-The thickness of the surface active layer is about 200-250m.
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SOME STUDIED RESULTS ON EROSION AND DEPOSITION IN THE COASTAL AREA OF BINH THUAN PROVINCE
 Bui Hong Long
 Institute of Oceanography (Nha Trang) 
 
Abstract:
   The paper is focused on some investigated and studied results in the coastal area of Binh Thuan province of state level project titled “Study on forecast and prevention of coastal erosion in the South of Vietnam” (from Binh Thuan to Ha Tien in the period of 1999-2000.
The overviewed and field surveyed results have shown the status of topographic changes at the coastline of Binh Thuan and at some main point regions: Phuoc The, Phan Ri, Ham Tien (Phan Thiet). The wave characteristics were calculated based on wave monitoring data at Phu Quy island. The parameters of unusual frequency wave have been identified by Veibun calculation based on long period wind field. The reasons of erosion have been dealed on the bases of endogenous and exogenous reasons. The forecast of erosion in the three mentioned regions is based on dynamic formatic methods and scenario of global sea level changes.
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IDENTIFICATION OF WATER ZONES IN THE CENTRAL OFFSHORE SEA REGION OF VIETNAM BY USING DATABASE OF SEAFDEC CRUISE, 4-6/1999
 La Van Bai
Institute of Oceanography (Nha Trang) 
 
Abstract:
   In the paper, the principal component method was applied for identification of water zones with different thermohaline and hydrological structures in the central offshore sea region of Vietnam in KC-0903 project. On the basis of Seafdec cruise data during 4-6/1999, the author completely used 7 hydrochemical and hydrological structure elements: depth of thermocline, depth of maximal chlorophyll, transparency, depth of maximal density gradient, depth of homogenous layer, surface temperature and salinity, to analyse their correlations and to identify 8 “water zones” with the different thermohaline and hydrological structural properties.
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DISTRIBUTION OF THE WAVE CHARACTERISTICS IN THE TYPICAL MONSOONS IN THE EAST SEA
 Nguyen Ba Xuan, Le Dinh Mau
 Institute of Oceanography (Nha Trang) 
 
Abstract:
   This paper introduces the calculated results of wind wave characteristics in the typical north-eastern and south-western monsoons in the East Sea. In the north-eastern monsoon, with a wind force of 5–6 grade, the central, northern regions of East Sea and the coastal southern part of central region are impacted by strong waves (Hs » 2-3m), Thailand bay - by weak waves (Hs < 1m). In the south-western monsoon, the Tonkin and Thailand bays are impacted by weak waves (Hs < 1m), the coastal southern part of central region - by moderate waves (Hs » 1–1.5m) and the central region of East Sea - by strong waves (Hs » 1.5–2.5m).
 
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FEATURES OF CYCLONE IN THE HOI AN AREA
Le Dinh Mau
Institute of Oceanography (Nha Trang) 
 

Abstract:
   The data of cyclones in Hoian and adjacent area  (140N to 170N) during 1945 - 2003 were taken from the National Weather Service (USA) by Internet. The features of storm such as track, intensity, time and frequency of occurrence have been considered. Radius of area of maximum wind speed (R) was estimated using the Saffir-Simpson scale. For four typical cyclones reported in 1964, 1989, 1997 and 1999 the maximum significant wave height (Hs) and spectral peak period (Tp) were estimated using the Young’s model considering the moving wind field. The study results showed that:
- In all 69 cyclones occurred in Hoian and adjacent area during 1945-2003 (with an average of 1.2 times a year), there were 36 severe cyclones (typhoon) with maximum wind speed Vmax > 33m/s, 20 normal cyclones (tropical storm) with 17m/s < Vmax < 33m/s, and 13 light cyclones (subtropical storm) with Vmax < 17m/s. The cyclones were mostly concentrated in September (26.1%), October (30.4%) and November (13%). In general, the radius of area of maximum wind speed was 34 km.
 - During typical cyclones in the offshore of the Hoian maximum significant wave height was 10.5m, the spectral peak period was 13.3s, and the incident wave direction was from N-NE.
- The computed results from Young’s model are suitable with the results of hurricane wave predicted by techniques of SPM (1984).

 
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NATURAL AND ARTIFICIAL RADIOACTIVITY IN THE NEUTER SEA OF SOUTHERN CENTRAL VIETNAM
 Nguyen Tac An, Vo Duy Son, Phan Minh Thu
 Institute of Oceanography (Nha Trang) 
 
Abstract:
   Based on the surveys about radioactivities in the neuter sea of Southern Central Vietnam during period of 1998–2002, the paper presented status of environmental radionuclides of 137Cs, 210Pb, 226Ra and 228Rain seawater and organisms in coastal waters of Khanh Hoa province as well as in sediment in the Southern Central Vietnam. The results showed that their radioactivities were the same as the radioactivity background in coastal and marine areas of Asia and over the world. In addition, the results also indicated that brown seaweed species could be used as environmental nuclear bioindicators. This may be applied for monitoring of marine environment.
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THE RAPID ASSESSMENT OF ENVIRONMENTAL QUALITY IN HA LONG BAY BY THE TECHNIQUE OF BIOTOK-TEST
Nguyen Huu Huan & Ho Hai Sam
 Institute of Oceanography (Nha Trang) 
 
Abstract:
   The technique of Biotok-Test has become more and more popular for studying and assessing environmental quality by its advantages. Based on the data investigated by the technique of Biotok-Test in August 2002, this paper presents the assessment of environmental quality in Ha Long bay. The results show that:
- The water quality in Ha Long bay is relative good with the average “T” value ranged between 1.5 ± 0.2 and 6.3 ± 1.2 (T<20). The central area of the bay is the best in the whole bay.
- Contrarily, the whole sediment in Ha Long bay is poisoned at different levels. The sediment of area between Bai Chay and Cua Luc is the worst with average “T” value of 71.66 ± 7.3 (T >70). The sediment of areas: around Bai Chay, Hon Gai – Cam Pha and around Tuan Chau island is just poisoned at the average “T” value of 56.81 ± 5.2 (T >50). The sediment of center of Ha Long bay is relative good with average “T’ value of 40.7 ± 2.7 (T < 50).
In general, there was the decline of environmental quality in Ha Long bay, especially in sediment. This has affected living resources, especially eggs and larvae because they are sensitive to their living environment. In addition, it has affected human health because it has affected quality and safety of aquatic products.
 
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SOME NEW RECORDED SPECIES FOR THE GENUS GRACILARIA OF VIETNAM
 Le Nhu Hau
Institute of Materials Science – Nha Trang Branch 
 
Abstract:
   Five species of the red algal genus Gracilaria from Vietnam which are described as new records for Vietnam: Gracilaria cuneifolia (Okamura) Lee et Kurogi, Gracilaria rubra Chang and Xia, Gracilaria stellata Abbott, Zhang et Xia, Gracilaria yamamotoi Zhang et Xia, Gracilaria longirotris Zhang et Xia.
 
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PHYTOPLANKTON IN LANG CO LAGOON, CENTRAL VIETNAM
 Doan Nhu Hai, Nguyen Ngoc Lam, Nguyen Thi Mai Anh, Ho Van The
Institute of Oceanography (Nha Trang) 
 
Abstract:
   One hundred and forty-four species of phytoplankton were registered from 2 surveys in February and June 2001 in Langco lagoon. Diatoms were the most abundant in species number, and following to be Dinoflagellates. There were also three species of Silicoflagellates, one species of Ebriids, and one species of Cyanobacteria in phytoplankton communities. 17 species of potentially toxic algae were found, among them there were 14 species and 10 species  observed in the rainy season and the dry season, respectively. Genus Alexandrium seemed to be high diverse in period of low temperature and low salinity while Dinophysis in reverse condition.
Cell densities differentiated between the two samplings, but there was not significant difference in carbon biomass. The high cell densities were dominated by Diatoms in the dry season and the high carbon biomass were dominated by Dinoflagellates in the rainy season.
 
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ZOOPLANKTON IN NHA TRANG BAY
Nguyen Cho
 Institute of Oceanography (Nha Trang) 
 
Abstract:
   The paper presents the results of the survey on zooplankton in Nha Trang bay (Khanh Hoa province) in 2003. One hundred and ninety-two species had been identified, among them Copepods were dominant with 60% of total species. The average biomass of zooplankton was 82 mg.m-3, ranging from 27 mg.m-3 to 205 mg.m-3. The lowest and highest densities of zooplankton were recorded in June (Southwest Monsoon) and December (Northeast Monsoon) in 2003 with 3,289 inds.m-3 and27,593 inds.m-3, respectively. The average density was 8,544 inds.m-3. The highest biomass was also recorded in the intermonsoon period. In addition to that, the biomass seems to be concentrated in the southern part of the bay (Stations 5 and 6).
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FISH EGGS AND LARVAE THROUGH THE TRANSECT OF NHA TRANG (VIETNAM) – LUZON (PHILIPPINES) IN 2000
 Vo Van Quang, Nguyen Huu Phung, Tran Thi Hong Hoa
 Institute of Oceanography (Nha Trang) 
 
Abstract:
   The fish eggs and larvae were analyzed and treated basing on the collected data of a transect from Nha Trang (Vietnam) to Luzon (Philippines) survey in May – June, 2000. Some different environmental factors of the stations are remarked to consider the relation between them and egg and larval distribution.
There are 158 eggs and 625 larvae collected. Mean densities of egg and larvae in DV - 80 net were 12.61 eggs and 55.59 larvae/100m3 and DV – 50 net were 17.73 eggs and 53.72 larvae/100m3. The fish eggs concentrated in the western offshore area (Vietnam): 17.33 eggs and in the eastern offshore area (Philippines): 16.00 eggs/100m3, meanwhile they are less than fivefold  around the Spratly islands. The main composition of fish eggs and larvae are lantern fishes (Myctophidae) 41.02%, bristle mouths (Gonostomatidae) 15.96% and some coral fish families such as gobies (Gobiidae): 3.99%, surgeon fishes, tangs, unicorn fishes (Acanthuridae): 2.44%, groupers (Serranidae): 1.33%....
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FISH RESOURCES AND THEIR UTILIZATION IN DEGI LAGOON – BINH DINH PROVINCE
Nguyen Van Luc*, Nguyen Tac An*, Nguyen Phi Uy Vu*,
Le Thi Thu Thao*, Tran Van Lang**, Nguyen Thi Lien**
 * Institute of Oceanography (Nha Trang)
** Binh Dinh Fisheries Department 
 
Abstract:
   Based on fishing data collected in October 2001 to June 2003, a total number of 51 fish species was identified. The fish species composition in De Gi lagoon is similar with Thi Nai. Total fishing catches are about 300 – 500 metric ton/year, including shrimps/crabs 30 - 50 metric ton, anchovy 40 - 70 metric ton, white sardine 30 – 40 metric ton, milkfish 40 - 50 metric ton, ...There are fishing seasons in around year, but mainly in rainy season. Fish stock is estimated 600 – 700 metric ton (about 46 – 47% ecological carrying stock) with maximum sustainable yield of 300 – 350 metric ton.
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SOME BIOLOGICAL CHARACTERISTICS OF JAPANESE THREADFIN BREAM NEMIPTERUS JAPONICUS (BLOCH, 1791) IN THE MARINE REGION OF NHA TRANG, KHANH HOA PROVINCE
 Ho Ba Dinh, Le Trong Phan, Nguyen Huu Phung
Vo Van Quang and Tran Thi Hong Hoa
Institute of Oceanography (Nha Trang) 
 
Abstract:
   Japanese threadfin bream Nemipterus japonicus (Bloch, 1791) is a commercial fish and occupies the high rate of fisheries. Based on the data collected in 2003 (from February to October) of the fisheries by trawl in Nha Trang (Khanh Hoa province), this paper presents some results on catch length, age, growth rate, length-weight relationship, periods of spawning and feeding intensity of this species.
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OBSERVATION OF TETRODOTOXIN (TTX) IN THREE SPECIES OF PUFFER FISH MONTHLY COLLECTED AT CUA BE (NHA TRANG- KHANH HOA) IN 2002
Do Tuyet Nga, Pham Xuan Ky, Dao Viet Ha
 Institute of Oceanography (Nha Trang) 
 
Abstract:
   In Torquigener pallimaculatus Hardy, Tetrodotoxin (TTX) was always found in the ovaries and livers, seldom in the viscera of both the female and male fish, only once in the skin of the male fish. This species highly concentrated TTX in the samples of May, September and November. In Lagocephalus lunaris (Bloch & Schneider), TTX was found in the ovaries and livers of the female fish collected in September and November. In Arothron immaculatus (Bloch & Schneider), TTX was only found in the ovaries, high in the samplings of May to September, much higher than two above species.
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TRIAL for CULTURING COMMERCIAL GREEN MUSSEL PERNA VIRIDIS (Linnaeus, 1758) IN NHA PHU LAGOON - KHANH HOA
 Vo Si Tuan, Truong Si Ky, Ha Le Thi Loc,
Hua Thai Tuyen, Nguyen Thi Kim Bich
Institute of Oceanography (Nha Trang)
 

Abstract:
   The Green Mussel (Perna viridis) was cultured at Nha Phu lagoon from July 2001 to July 2002 on three kinds of materials: timber stakes, rope strings and cement block plates. Growth, survival rate and economical effects of these culture styles were assessed after 11 months as following:
The growth per month for rope string cultured style was the lowest (4.02 mm/month), the second was cement plate cultured style (4.65 mm/month). The Green Mussel cultured on wood stake style showed the highest growth rate (4.99 mm/month).
Survival rate of mussel after three months was 61% for rope string, 86% for wood stake, and 63% for cement plate. After 11 months of culture, the survival rate was lowest on rope string (14%), and then on cement plate (27%), the highest survival rate was on wood stake, 35%.
In three trial culture models, both models of mussel culture on rope string and cement plate were not effective. The wood stake models showed highest effectivity, with 26% profit.

 
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SOME NUTRITIOUS CHARACTERISTICS OF TOMATO ANEMONE FISH Amphiprion frenatus Brevoort, 1856  IN NHA TRANG – KHANH HOA COAST
Ha Le Thi Loc
Institute of Oceanography (Nha Trang)
 
Abstract:
   Feeding habits of the Tomato Anemone Fish, Amphiprion frenatus, were investigated by analyzing stomach contents of 144 specimens caught from October 2001 to September 2002 in Nha Trang – Khanh Hoa coastal waters, showed that they eat miscellaneously. The food spectrum was quite wide and food web was short. Their main nutrition contents were Copepoda (34.61%), fish eggs (11.21%), Tunicata (9.97%), fish scales and fins (10.98%). Moreover, some different foods as: Algae, Bivalve, Gastropoda, Nematoda, Isopoda, Amphipoda, Cladocera, Mysidacea occupied a small portion. Full grade was rather full and stable: almost they had grades of V and IV (74.99%), some of them had ball I (only 6 inds, 4.16%) of studied samples. Fatty index of Tomato Anemone Fish was high in February, March, April (from 2.6% to 2.81%) and low in October and November (2.18% and 2.24% respectively).
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HAEMOLYMPH OSMOLALITY, TAIL MUSCLE MOISTURE CONTENT AND THE EFFECTS OF AIR EXPOSURE ON THE OSMOREGULATORY CAPACITY OF THE WESTERN KING PRAWN (PENAEUS LATISULCATUS KISHINOUYE, 1896) REARED AT DIFFERENT SALINITIES
Huynh Minh Sang
 Institute of Oceanography (Nha Trang) 
 
Abstract:
   Haemolymph osmolality and tail muscle moisture content of the western king prawn, Penaeus latisulcatus, (2.95 ± 0.26 g mean initial weight), were measured when reared at 10, 22, 34 and 46 ppt salinities for 60 days. In addition, osmoregulatory capacity (OC) of the western king prawn (5.37 ± 0.1 g mean initial weight) from four salinities (10, 22, 34 and 46 ppt) was determined following 7, 14 and 21 minutes air-exposure. Haemolymph osmolality increased with an increase in medium salinity and weight of the prawns. Isosmotic points calculated from regression between haemolymph and medium osmolality were 28.87, 29.46 and 31.73 ppt at 0, 20 and 60 days of culture, when body weights were 2.95 ± 0.26; 4.02 ± 0.47; 5.79 ± 0.64 g respectively. Tail muscle moisture content of the western king prawn decreased with an increase in salinity. OC of the western king prawn at salinity 10 ppt was reduced (P < 0.05) when exposed to 14 minutes of air. The results indicate that the prawns spent less energy (P < 0.5) for osmoregulation at 22 and 34ppt of salinity than at other salinities. The results suggest that this prawn should be cultured in range of salinity from 22 to 34 ppt.
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Written By: Administrator Account
Date Posted: 11/12/2007
Number of Views: 3047

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