Mostrando ítems 1-20 de 38639

    • Estimation of the spawning ground of some fish species in the Nha Trang bay

      Vo, Van Quang; Tran, Thi Hong Hoa; Tran, Cong Thinh; Le, Thi Thu Thao (2020)
      The paper presents the results of determining the spawning grounds of some fish species in Nha Trang bay MPA, which were sampled in 9/2018, 11/2018, 5/2019 and 7/2019. The analysis results are based on the distribution of the general density and the developmental stages, analysis of decision trees from egg density, location of stations and months by CHAID (Chi-square Automatic Interaction Detector), allowing a relatively accurate estimate of the spawning ground of the red anchovy (Encrasicholina punctifer Fowler, 1938) and the species of the genus Scarus. As a result, the main spawning grounds for red anchovy were the east of Hon Rua and the northeast of Hon Tam and that of Scarus is the southwest of Hon Mun island.
    • Captive culture of two sea snake species Hydrophis curtus and Hydrophis cyanocinctus

      Nguyen, Trung Kien; Hua, Thai An; Huynh, Minh Sang; Do, Huu Hoang; Cao, Van Nguyen; Ho, Thi Hoa (2020)
      Acclimation culture and trial culture of two sea snake species Hydrophis curtus and H. cyanocinctus in composite tanks were conducted to determine growth, survival rate, predation behavior and prey selection. The results showed that adults of H. curtus and H. cyanocinctus did not capture any prey such as anchovy, eel and shrimp in a period of 30 days of acclimation culture. The body weight of two these species reduced gradually from 783.3 ± 76.4 g and 360.0 ± 60.0 g to 660.0 ± 135.2 g and 315.0 ± 77.8 g, respectively. Survival rate was 100% in H. curtus and 80% in H. cyanocinctus. Meanwhile, the results of acclimation culture of sea snake juvenile revealed that frozen anchovy was preferred prey in both of two species. The body weight of H. curtus increased from 49.8 ± 0.5 g to 70.0 ± 8.2 g and that of H. cyanocinctus was 44.3 ± 3.1 g to 47.1 ± 5.2 g. The prey capture rate of H. curtus and H. cyanocinctus was 100% and 60%, respectively. Survival rate of the juvenile of two species was 100% after 30 days of acclimation culture. In 60 days of trial culture, similar results as acclimation culture were observed in adults of two sea snake species, they still did not capture any prey and the body weight reduced gradually. The result of 60-day culture of sea snake juvenile showed that the prey capture rate was 100% in both of two species. The body weight of H. curtus and H. cyanocinctus increased from 70.0 ± 8.2 g and 57.5 ± 5.8 g to 78.3 ± 15.3 g and 65.0 ± 14.1, respectively. SGR of H. curtus was 0.16 ± 0.32 %/day and that of H. cyanocinctus was 0.52 ± 0.36%/day. The survival rate of H. curtus and H. cyanocinctus was 60% and 40% in period of 60 day trial.
    • Morphology, abundance and the invasiveness of coral-killing sponge Chalinula nematifera (Porifera: Demosponigiae) from Con Dao National Park, Vietnam

      Thai, Minh Quang (2020)
      This is the first study on morphology, abundance and invasion of coral-killing sponge Chalinula nematifera (De Laubenfels, 1954) from offshore waters in Con Dao islands, Vietnam. The results of the study show that the morphology is similar to that in the Western Pacific, but differs in skeletal structure compared to the description in the Eastern Pacific. The density of C. nematifera (average ± standard deviation) is 2.02 ± 5.03 colonies per 100 m2 (present at 12/15 survey stations) with the number of colonization belonging to diameter group 5–20 cm. They invade 30 species belonging to 23 genera of Scleractinia corals (44.7% on foliose/laminar and encrusting coral, 23.86% on massive coral and 21.97% on branching coral). The ability to invade corals of C. nematifera does not limit the host. So, this is considered a potential hazard to the East Vietnam Sea coral reefs in the future.
    • Some species of macro-gastropods in the coastal zone of Khanh Hoa province

      Bui, Quang Nghi; Nguyen, Thi My Ngan; Nguyen, Kha Phu (2020)
      From November 2013 to March 2014, 104 species were collected, belonging to 27 families, 58 genera of Gastropoda in coastal area of Khanh Hoa province. Some families have a large number of species such as Conidae - 15 species; Strombidae - 15 species; Cypraeidae - 10 species; Terebridae - 7 species and Muricidae - 6 species. Many species of economic value are used for food and fine arts. 11 species are listed in Vietnam Red Data Book. Besides, images and information of samples (collecting date, place of sample collection,...) are presented.
    • Species composition and distribution of seaweeds in Phu Yen province

      Nguyen, Thi Thu Hang; Nguyen, Van Tu; Vo, Van Phu; Nguyen, Ngoc Lam (2020)
      Results of four field surveys, conducted from June 2017 to June 2018 found that in the Phu Yen coastal water, a total of 103 seaweed species have been recorded, increasing the total number of seaweed species in Phu Yen province to 133 species, with 81 newly recorded species for Phu Yen geographic area. Among 103 seaweed species, 4 species belong to Cyanobacteria, 38 species belong to Rhdophytes, 24 species belong to Phaeophytes, and 37 species belong to Chlorophytes. The number of species at surveyed sites V1 to V9 varies from 3 species/site (V3) to 83 species/site (V7) and on average 27 species/site. Sørensen’s similarity coefficient varies from 0.05 (between V3 and V7) to 0.86 (V3 and V4) and on average 0.25. 74/103 species were collected in the littoral zone, 67 species in sublittoral zone and most of them are distributed at 0-4 m water depth of subtidal zone. The marine algal flora is represented by mixing of subtropical and tropical characteristics as Cheney index was 3.
    • Assessment of effective coral rehabilitated in Marine Protected Areas of South Vietnam

      Hoang, Xuan Ben; Vo, Si Tuan; Phan, Kim Hoang (2020)
      More than 20,300 fragment corals belonging to 24 species, eight genera and six families were rehabilitated in marine protected areas of south Vietnam. Mean survival rates of coral fragments ranged from 60–97.7%, the average growth rate of the branched corals was 4.8 mm/month meanwhile the foliose coral was 1.9 mm/month. The survival and growth rate of corals are different among areas because each coral species has different biological characteristics, structure colonies and due to differences in natural conditions each area. The results showed that the growth rate of corals will return to normal after 4 months rehabilitation. The factors affected the effective coral rehabilitation including: Coral reef predators, spatial competition among species, environmental conditions change due to human’s activities; and other factors such as hydrodynamic regimes, cutting fragment corals cause its injury damage. The rehabilitation and protection activities of coral reefs in marine protected areas should be continued and expanded, contributing to the protection of biodivesity, marine resource and sustainable coral reefs ecosystem development.
    • Bleaching of coral in Nha Trang, Ninh Thuan, Con Dao and Phu Quoc islands in June–July 2019

      Phan, Kim Hoang; Vo, Si Tuan; Thai, Minh Quang; Dao, Tan Hoc; Hua, Thai Tuyen (2020)
      The studies on coral bleaching were conducted at 21 sites of 4 reef areas in Southern Vietnam, using point transect technique in June–July 2019. Cover of hard corals in the selected sites was quite high with the average values of 65.6 ± 18% % in Con Dao islands, 58.7 ± 26.2% in Ninh Thuan coastal waters, 55.9 ± 17.8% in Phu Quoc island but lower in Nha Trang bay (22.8 ± 15.9%). Soft corals were not abundant with the highest cover in Nha Trang bay (4.73 ± 5.5%) and the lowest in Ninh Thuan (0.16 ± 0.3%). Hard corals were most impacted in Nha Trang bay with 39.5 ± 8.1% bleached, followed by Ninh Thuan reefs (32.9 ± 13.3%), Con Dao Islands (25.0 ± 11.1%) and least affected in Phu Quoc island (7.3 ± 9.05%). For soft corals, ratios of bleached corals were 79.4%, 65.8% and 23.8% in Con Dao islands, Nha Trang bay and Ninh Thuan reefs respectively. No bleached soft coral was recorded in Phu Quoc. At the genus level, Acropora corals were severely affected in Nha Trang bay, Ninh Thuan reefs and Phu Quoc island but not impacted in Con Dao islands. The Porites, Montipora, Millepora genera were quite vulnerable in all sites but no bleaching was observed for Galaxea and Diploastrea genera.
    • Relación entre las variables ambientales y el crecimiento de Pteria colymbus (Mollusca Bivalvia: Pteriidae), en tres profundidades de cultivo

      Felipe Freites, Luis; Guevara, Miguel; Márquez, Adrián; Revilla, Jormil; Narváez, Mariela; Lodeiros, César (2020)
      Se estudió la influencia de las variables ambientales asociadas con tres profundidades de agua (2, 6 y 10 m) en el crecimiento de la concha, la masa seca de los tejidos blandos (MSTB) y la supervivencia de la ostra alada del Caribe Pteria colymbus (Roding, 1798). La clorofila a (Chl-a), el oxígeno disuelto, la materia orgánica particulada (POM) y la temperatura se estudiaron a cada profundidad. Las ostras se colocaron en 135 cestas de plástico con cinco individuos en cada cesta. Se eligieron tres cestas en cada profundidad a intervalos mensuales para las mediciones de parámetros biométricos, bioincrustaciones y supervivencia. Al final del estudio, la masa seca de los individuos cultivados a 10 m fue significativamente menor (prueba no paramétrica de Kruskal-Wallis KW, P < 0,05), mientras que los valores más altos de MSTB correspondientes a las ostras cultivadas a 2 m de profundidad. El análisis del componente principal mostró una relación inversa (temperatura) y directa (Chl-a y POM) con la varianza observada en el MSTB. Teniendo en cuenta los resultados obtenidos en los rendimientos (crecimiento/supervivencia) de P. colymbus, recomendamos llevar a cabo su cultivo a profundidades de agua entre 2 y 6 m.
    • Levels of heavy metals in seawater, sediment and in the tissue of Crassostrea belcheri in the Western estuary of Ganh Rai bay

      Le, Hung Phu; Nguyen, Hong Thu; Pham, Hong Ngoc; Le, Trong Dung; Dao, Viet Ha (2020)
      Recent studies have shown that the seawater, sediment and commercial bivalve molluscs in the studied area have been contaminated by some heavy metals Zn, Cu, Pb and Cr. Highly toxic heavy metals like As, Cd, Pb, Hg have tended to accumulate in the tissue of clams. This paper presents the levels of some heavy metals in the seawater, sediment and soft part of oyster (Crassostrea belcheri) samples collected from the western estuaries of Ganh Rai bay in 2015 and 2017. The results also showed that Ha Thanh and Rach Lo sites recorded the highest contents of most studied metals in oyster samples. Levels of metals in oyster were in the order of Zn > Cu > As > Pb > Cr > Cd > Hg and the contents of metals in oyster did not reflect a correlation with those in surrounding environment. Concerning food safety criteria, Pb, Cd and Hg contents were lower than acceptable limit given by the compilation of FAO (1983), whereas As, Cu and Zn contents exceeded the legal limit, especially Zn contents. Cu and Cr contents in sediment samples of Nga Bay and Dong Hoa estuaries were between LEL-SEL values (≥ LEL and < SEL), which may cause biological impacts at moderate level.
    • Zooplankton community in Thi Nai lagoon in the period of 2001-2020

      Nguyen, Tam Vinh; Doan, Nhu Hai (2020)
      This paper presents the results of the surveys on zooplankton in Thi Nai lagoon from 2001 to 2020. There were 179 species found in the lagoon, among which Copepod was the dominant group with 97 species (50.78% of total species), followed by Cladocera with 20 species (10.36%), Hydrozoa with 18 species (9.33%), Tunicata with 11 species (5.7%) and Siphonophora with 10 species (5.18%). Based on Bray-Curtis similarity analysis of zooplankton community and the station position, the sampling stations in the lagoon were grouped into three areas: The upper lagoon (UP), the middle (MI), and the mouth of the lagoon (MO). Among the surveyed years, there was a slight variation in the species number, while the density decreased by time and was especially low in 2020. Zooplankton density was much lower in the rainy season compared to that in the dry season, while the species number was less varied. Analysis of the differences between the areas in the lagoon demonstrated a clear distribution pattern of zooplankton with a decreasing density and an increasing number of species from upper lagoon to the mouth of the lagoon. Zooplankton diversity was less affected by time and only the Pielou index in the MI area between 2004 and 2009 was significantly different. Analysis of the various indices between seasons showed that the MO area was less volatile than the two other regions. The multi-dimensional scaling analysis demonstrated that zooplankton community was less variable by regions (50% similarity) compared to by the years (only 30% of similarity), except in 2009 and 2020 when differences among the areas were significant. Seasonal community change between the dry and rainy seasons was 30%.
    • Variation of phytoplankton community structure in Quang Ngai coastal waters during 2015-2019

      Huynh, Thi Ngoc Duyen; Tran, Thi Minh Hue; Tran, Thi Le Van; Phan, Tan Luom; Nguyen, Ngoc Lam; Doan, Nhu Hai (2020)
      Phytoplankton in coastal waters are important for the evaluation of either biodiversity or environmental impacts because of this highly vulnerable ecosystem. Seasonal and annual changes in the phytoplankton community structure in Quang Ngai waters during the period 2015 to 2019 were analyzed to assess the phytoplankton diversity and reveal possible causes of these changes. A total of 366 phytoplankton taxa belonging to 10 classes were identified throughout this present study. The highest species number was found in 2019 with 295 taxa, followed by those in 2015 (247), 2017 (185), and 2018 (99). The waters of Ly Son transect showed the highest diversity and most stable phytoplankton communities in both dry and rainy seasons, whereas the stations of Quang Ngai coast revealed high variability of the communities. All diversity indices including Margalef, Pielou, Shannon, Simpson did not reflect well differences in average values but a certain degree of variances, indicating possible environmental impacts. During the study time, there were blooms of certain diatom species including Skeletonema spp. in 2015 and Pseudo-nitzschia spp. in 2019. Analysis of a diatoms index, Centric/Pennate ratio, indicated that the waters were in eutrophic status with a decreasing trend from the coast area to Ly Son island in 2015 and 2019. This research built up fundamental data on phytoplankton communities for Quang Ngai province. The Centric/Pennate diatom index and diversity would be used as indicators for environmental changes and their values provided warning of eutrophication in this coastal waters including the water surrounding Ly Son island.
    • Los peces triple aletas del Santuario de Fauna y Flora Malpelo, Pacífico colombiano

      Rojas-Vélez, Stephania; Beltrán-León, Beatriz Susana; Tavera, José; Instituto de Investigaciones Marinas y Costeras “José Benito Vives de Andréis” (2021)
      La familia Tripterygiidae incluye a los peces conocidos como triple aletas por la división en tres segmentos que caracteriza la aleta dorsal de sus especies. De las 183 especies reconocidas como válidas para la familia solamente 16 se distribuyen en el Pacífico oriental, incluyendo dos endémicas y únicas representantes de la familia en el Santuario de Fauna y Flora Isla Malpelo: Axoclinus rubinoffi y Lepidonectes bimaculatus. El presente trabajo aporta datos morfológicos y ecológicos de la etapa larval y adulta para las dos especies de triple aletas del santuario. Con respecto a las larvas, la abundancia promedio fue de 1,88 individuos/m2 para A. rubinoffi y 0,25 individuos/m2 para L. bimaculatus en las estaciones nocturnas donde fueron recolectadas, a 0,8 y 1,61 km de distancia al occidente y en localidades muy cercanas a la isla como El Arrecife y La Nevera. Los adultos fueron recolectados alrededor de la isla entre 0-30 m de profundidad y su abundancia fue de 0,22 individuos/m2 para L. bimaculatus y de 0,19 individuos/m2 para A. rubinoffi. Se amplía el conocimiento de la variabilidad natural de los rangos morfológicos de ambas especies y se evidencian diferencias entre las densidades poblacionales encontradas en previos estudios. Para entender las dinámicas poblacionales de estas
    • Study on distribution characteristics of wind speed field in the sea area of Ly Son island of Quang Ngai province

      Tran, Van Chung; Ngo, Manh Tien; Nguyen, Van Long (2020)
      On the basis of the data source of the 10 m wind field above the sea with the hourly frequency and during the period of 41 years (1979–2019) by the NCEP CFRS, we used the probability distribution functions to study the distribution law of wind speed in the waters of Ly Son island. Specifically, four distribution functions (normal distribution, gamma distribution, Weibull distribution and extreme value distribution) were used to estimate the characteristic parameters of the shape and proportion of the wind distribution in the waters of Ly Son island.
    • Fluctuations of wind and temperature fields in Ninh Thuan-Binh Thuan waters and its possible relationship with coral bleaching

      Van Chung, Tran; Manh Tien, Ngo; Van Nguyen, cao (2020)
      Temperature and wind on the sea surface are factors affecting the development of coral reefs in the seawaters. The research results show that the warming of sea water under the condition of weak wind field is considered a major threat to the bleaching of coral reefs in the sea areas of the Ninh Thuan - Binh Thuan provinces.
    • International Coastal Atlas Network Newsletter Vol. 9 No. 2

      Sherin, Andrew (International Coastal Atlas NewtorkHalifax, Nova Scotia, Canada, 2020-12)
      This issue the ICAN newsletter focuses again on the UN Sustainable Development Goals with articles on the Global Partnership for Sustainable Development Data and other SDG relevant articles. It has a highlighted article on the Maryland Coastal Atlas and an update on the Ocean Information Hub.
    • Водные биоресурсы и среда обитания. Том 4, вып. 2

      Bragina, T.M. (Azov-Black Sea Branch of the FSBSI “VNIRO” (“AZNIIRKH”)Rostov-on-Don, Russia, 2021)
      Chlorophyll-α in the Azov Sea has been studied according to the data of remote sensing of the Earth collected in 2006–2019. Biology and spatial distribution of roach Rutilus rutilus heckelii and common bream Abramis brama juveniles in the Don River have been characterized for the period of 2020. Abiotic environmental factors in classification of the water from energy facilities have been investigated for aquaculture purposes. Reproduction results of the semi-anadromous fish species at the floodplain spawning and rearing farms (hatcheries) of the Azov Sea and Kuban River region have been summarized for 2020. Preservation techniques for zostera (eelgrass) washed ashore as storm debris are described. Long-term dynamics of the bream stocks in the Azov Sea (Russian waters) has been tracked based on the results of CMSY modeling under the conditions of limited data availability (2002–2020). Possibilities of the short-term forecast of the catch of the European sprat from the Black Sea stock off the western coast of Crimea are suggested.
    • Book Abstract "Physiological and genetic aspects of so-iuy mullet Planiliza haematocheila (Temminck & Schlegel, 1845) biology in the Azov and Black Sea Basin"

      Azov-Black Sea Branch of VNIRO (2021)
      This work characterizes the physiological status of so-iuy mullet Planiliza haematocheila (Temminck & Schlegel, 1945) upon formation of its broodstock at the beginning of its acclimatization (1979–1983) in the Azov and Black Sea Basin. Following the results of a long-term investigation, age-length, seasonal, and annual dynamics of physiological parameters have been identifi ed, as well as specifi c features of so-iuy mullet metabolism and reproduction.
    • Possibilities of short-term forecasting of the catch of the European sprat from the Black Sea stock off the western coast of Crimea

      Panov, B.N.; Spiridonova, E.O. (2021)
      This research work presents the results of the analysis of the data collected during the multimethod monitoring of the European sprat fishing (the Black Sea stock) off the western coast of Crimea in July–September, 2019. The monitoring was aimed at identification of a relationship between the behavior of biological resources and their environmental conditions with the purpose of developing the methods of short-term forecasting of fishing efficiency. Graphical and correlation analysis of the daily data on vessel catches and sea surface temperature, as well as satellite altimetry data and characteristics of atmospheric transfers in the fishing area made it possible to suggest an environmental mechanism for the formation of commercial sprat aggregations in the investigated area. During its summer feeding in the coastal waters, sprat forms denser aggregations under the influence of synoptic anticyclonic vortices that develop near the shelf. Intensification of those aggregations is associated with an increase in the western atmospheric transfers in this region. Southern currents, uncharacteristic for the investigated area, and a decrease in the temperature of surface waters in the coastal zone indicate escalation of the stable impact of anticyclonic vortices on the coastal waters. The presence of statistically significant anticipatory relationships between average daily fishing pressure and abiotic factors holds a promise for the possibility of short-term forecasting of the sprat fishing efficiency off the western coast of Crimea in the summer season with the forecast interval equaling 1–7 days.
    • Long-term dynamics of the bream stocks in the Azov Sea (Russian waters) based on the results of CMSY modeling under the conditions of limited data availability (2002–2020)

      Cherednikov, S.Yu.; Piatinskii, M.M.; Kozobrod, I.D. (2021)
      Analytical assessment of the Azov Sea stock of the common bream Abramis brama (Linnaeus, 1758) for the time range 2002–2020 has been performed using CMSY trend model in R that is suitable for application in the context of limited data availability. Current state of the stock is at the level of the reference point based on stock biomass, and shows evidence of substantial overexploitation (B2020/BMSY=0.989; F2020/FMSY=1.82). Accounting for the volumes of IUU-fishing using indirect estimates increases comprehensiveness of the results and ensures adequate stock assessment and evaluation of fishing mortality. Pooled estimates of bream stock biomass for the investigated period indicate a collapse of population abundance that fell upon 2005–2013 and, presumably, stemmed from climatic and hydrochemical changes in the Azov Sea environment, not being associated with overexploitation of the population in those years. At present, the bream population still remains in depressed state, with prerequisites for stock recovery. Following the results of modeling and after a consideration of forecast scenarios, the size of recommended legal catch for 2022–2023 could be set within the range between 40 and 110 t, depending on the efficiency of control, accounting, prevention and suppression of IUU-fishing. So long as the population is exploited within these limits, stock biomass will remain at a safe level and has the possibility of reaching 950 t. The results of this investigation highlight the necessity of control and prevention of bream IUU-fishing in the Azov Sea and Don River Basins; this is a crucial factor influencing bream population in the recent years.
    • Preservation techniques for zostera (eelgrass) washed ashore as storm debris

      Bogomolova, V.V.; Belyakova, I.A.; Esina, L.M.; Chernyavskaya, S.L.; Krivonos, O.N. (2021)
      The results of organoleptic evaluation of seagrass Zostera marina (eelgrass) storm debris are presented. The chemical composition of Zostera during its mass aggregation along the wrack line of the Black Sea coast in the spring and summer seasons of 2020 has been investigated. The safety of Zostera storm debris for consumption has been evaluated based on such indicators as content of radionuclides and toxic elements, and microbiological characteristics. Preservation of the storm debris samples has been conducted using the following techniques: drying under natural conditions (average daily air temperature 19–25 °С, wind velocity 5–8 m/s, atmospheric humidity 56.5–80.0 %, height of a storm debris layer 5–10 cm), artificial drying (forced ventilation at 40±2 °С, layer height 5–10 cm), and salting (using dry method with addition of table salt in the amount equal to 20 % of the weight of macrophytes). Organoleptic properties of dried and salted eelgrass under various storage times are described. It has been established that the eelgrass, inhabiting the Azov and Black Sea Fishery Basin and washed ashore, contains from 16.9 to 25.7 % pectic substances, which indicates high value of this macrophyte. A method of preservation does not severely affect the content of pectic substances. Recommendations on eelgrass preservation by means of drying (both under natural and controlled conditions) and salting have been given to ensure the highest possible retention of its quality.