Ca Mau Province Research Articles

Thành phần loài cá trong vùng đệm khu bảo tồn U Minh Thượng và U Minh Hạ

U Minh National Parks, which comprises of U Minh Thuong (UMT, Kien Giang province) and U Minh Ha (UMH, Ca Mau province) with the typical Melaleuca forest ecosystem submerged in aluminum soil is a habitat for many freshwater fish species. This study was aimed to identify fish composition distributed in areas around UMT and UMH National Parks. After the sampling period (09/2017 to 08/2019), 54 fish species were found belonging to 40 genera, 23 families and 10 orders in UMT, and 31 fish species belong to 22 genera, 13 families and 6 orders in UMH. Ooders Cypriniformes and Perciformes show high numbers of species in both two areas. Nevertheless, fish in UMT area is more abundant and diverse. Particularly, there were 4 orders, 10 families and 20 genera only appearing in UMT such as Cyclocheilichthys apogon, Clupeichthys aesarnensis, Macrognathus circumcinctus, Parambassis wolffii,… Conversely, two fish species including Amblypharyngodon chulabhornae and Parambassis siamensis were found only in UMH. Differences in fish composition can be explained by levels of water exchange inside and outside of National Park and degrees of alum intrusion in water in these two study areas.

Đặc điểm dinh dưỡng của cá sửu Nibea soldado (Lacepède, 1802)

A study on the nutritional characteristics of Soldier croaker Nibea soldado (Lacepède, 1802) was conducted from January to June 2019 in coastal areas from Soc Trang to Ca Mau provinces. Fish samples were collected monthly by trawl-net (engine capacity of 70 CV) with two groups of sizes such as juvenile (total length of 114-170 mm- small fish) and adults (total length of 209-370 mm- big fish). The results showed that the fish have wide mouth, long mouth and slanting; the jaw is very developed; gill rakers were sparse, short and hard to hold feed; esophagus was short, thick wall, with many folds; stomach was greatly expanded with the posterior portion, forming as a long sac, thick wall and many folds inside; caeca has 8-9 tubes with a sealed end attached to between the stomach and intestines; intestine was short, thick wall and folded in S-shape. Relative length of the gut (RLG)

Morphological and Histological Characteristics of Testis of the Goby Glossogobius sparsipapillus Living from Coastal Estuaries from Bac Lieu to Ca Mau

This study was conducted in the coastal estuaries in Bac Lieu and Ca Mau provinces in order to provide data on morphological and histological characteristics of as well as the spermatocyte development at every stage of the development of testis of goby Glossogobius sparsipapillus. The analysis results of 226 fish individuals, collected monthly from April 2019 to September 2019 by using the bottom nets, showed that the testis of this fish was double strands. In stage I, testis was small, thin and transparent; and the weight and size of testis increased from that stage onward. The colour of the testis became ivory white with the smooth and puffed surface. Spermatogonia were found through the cross-section of the testis in stage I, and then they were divided into primary spermatocytes and secondary spermatocytes, which were interlaced in stage II. In stage III, spermatids appeared in testicular lobes and developed into sperm in stage IV. This fish species is a multiple spawner during the breeding season, because there are several developmental stages of spermatocytes in their histology. This result is the basis for further research on artificial reproduction of this fish.
 Keywords: Bac Lieu, Ca Mau, Glossogobius sparsipapillus, reproductive form, testis.Keywords: Essential oil plats, life form, plants, Sop Cop nature reserve.
 References
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Exploring livelihood transitions in the Mekong delta

Important environmental and economic changes are transforming livelihoods in coastal communes throughout the Mekong delta. In the process, the historical reliance on rice farming and fishing has become less viable and sustainable, forcing households to construct more complex livelihood strategies. To document these livelihood transformations, we have analyzed primary survey data from 346 households across eight coastal communes in Ca Mau Province, located in the southern tip of Vietnam's Mekong delta. We find that there was a great deal of change in the livelihoods of survey respondents over the decade covered by the survey with over 40 per cent of all households reporting a change in their primary source of income. For the most part, these changing livelihood patterns describe a successful adjustment process whereby many households partly or completely left activities that did not offer high returns for other activities that offer more, or were able to combine livelihood activities to successfully adjust. However, we argue that not all fisheries‐based households have the financial or human capital to take advantage of the opportunities arising from Vietnam's seafood boom or economic development more generally. Poverty remains prevalent for those locked into extensive aquaculture and especially farming.

Application of remote sensing and GIS for assessing the level of change of land use status in the coast of Ngoc Hien district (Ca Mau province) due to the impact of sea level rise

Today, environmental hazards and challenges are no longer confined to the national or regional scale but on the global scale. One of the biggest challenges for humanity is the natural disasters, global warming and sea level rise. The natural disasters causing serious consequences for human life, such as: Storms, floods, earthquakes, tsunamis, desertification, high tides... increase in frequency, intensity and scale. In recent years, Ca Mau province as well as coastal provinces of Vietnam is under great influence due to the impacts of climate change. One of the most affected districts in Ca Mau province is Ngoc Hien district. The district has a geographic location with three sides bordering the sea, one side bordering the river, a completely isolated terrain. The terrain is flat, strongly divided by the system of natural rivers and canals and intertwined canals, so it is constantly flooded by the sea. Ngoc Hien district is characterized by a sub-equatorial monsoon climate, directly affected by irregular semi-diurnal regime. The main purpose of the paper is to assess coastal vulnerability due to the impact of climate change over time with GIS-based remote sensing images. Remote sensing data with multi-time characteristics, collected in many periods and covering a wide area is an effective tool for monitoring shoreline fluctuations in particular and land use status of the study area in general.

Potential exploitation reserves of middle - upper Pleistocene aquifer (qp<sub>2-3</sub>) in Ca Mau province

The paper presents the results of evaluating and determining the potential exploitation reserves of groundwater in Ca Mau province. In particular, the study has identified the regional hydrogeological parameters, assessed potential exploitation reserves of groundwater, forecasted water level fluctuations, determined quantities of groundwater supply from the sea and from rainwater according to space and time, and detailedly established input parameters and boundary value for hydrogeological modelling. Calculation results show that the total potential reserves of qp2-3 aquifer is 1,924,111 m3 per day, in which the fresh water is 1,072,145 m3 per day (accounting for 55.7%) and the salt water is 623,067 m3 per day (accounting for 44.3%).

Trade credit use by shrimp farmers in Ca Mau province

Purpose The purpose of this paper is to investigate the determinants of the amount of trade credit granted to shrimp farmers in Ca Mau. Design/methodology/approach Based on the literature review, the authors proposed six hypotheses on the determinants of the amount of trade credit granted to shrimp farmers. Data collected from 120 shrimp farmers in Ca Mau were used to test the proposed hypotheses. Findings Two out of six determinants, i.e. the size of input order (a pulling factor) and the competition among input suppliers (a pushing factor), are significantly positively associated with the amount of trade credit granted to shrimp farmers. No impact of the other determinants was found. The findings imply that shrimp farmers should join cooperatives to enhance access to trade credit and mitigate the risk for input suppliers. Originality/value This paper sheds light on the fact that trade credit is still granted to such risky buyers as shrimp farmers, which has not been explored by previous studies.

Community-wide Screening for Tuberculosis in a High-Prevalence Setting

BackgroundThe World Health Organization has set ambitious targets for the global elimination of tuberculosis. However, these targets will not be achieved at the current rate of progress.MethodsWe performed a cluster-randomized, controlled trial in Ca Mau Province, Vietnam, to evaluate the effectiveness of active community-wide screening, as compared with standard passive case detection alone, for reducing the prevalence of tuberculosis. Persons 15 years of age or older who resided in 60 intervention clusters (subcommunes) were screened for pulmonary tuberculosis, regardless of symptoms, annually for 3 years, beginning in 2014, by means of rapid nucleic acid amplification testing of spontaneously expectorated sputum samples. Active screening was not performed in the 60 control clusters in the first 3 years. The primary outcome, measured in the fourth year, was the prevalence of microbiologically confirmed pulmonary tuberculosis among persons 15 years of age or older. The secondary outcome was the prevalence of tuberculosis infection, as assessed by an interferon gamma release assay in the fourth year, among children born in 2012.ResultsIn the fourth-year prevalence survey, we tested 42,150 participants in the intervention group and 41,680 participants in the control group. A total of 53 participants in the intervention group (126 per 100,000 population) and 94 participants in the control group (226 per 100,000) had pulmonary tuberculosis, as confirmed by a positive nucleic acid amplification test for Mycobacterium tuberculosis (prevalence ratio, 0.56; 95% confidence interval [CI], 0.40 to 0.78; P<0.001). The prevalence of tuberculosis infection in children born in 2012 was 3.3% in the intervention group and 2.6% in the control group (prevalence ratio, 1.29; 95% CI, 0.70 to 2.36; P=0.42).ConclusionsThree years of community-wide screening in persons 15 years of age or older who resided in Ca Mau Province, Vietnam, resulted in a lower prevalence of pulmonary tuberculosis in the fourth year than standard passive case detection alone. (Funded by the Australian National Health and Medical Research Council; ACT3 Australian New Zealand Clinical Trials Registry number, ACTRN12614000372684.)

THE APPEARANCE OF FISHING COMMUNITY IN SONG DOC

In recent years, coastal fishing communities have increasingly become of interest due to the impacts that they have on the regions and communities they occupy and influence. To gain a better understanding of the contributions of fishermen to the socio-economic development of coastal areas, as well as the communities’characteristics, these fishing communities are necessary to investigate. This article focuses on the model of Song Doc fishing community (Tran Van Thoi district, Ca Mau province) to study the southern coastal fishing communities in Vietnam. Qualitative research methods were used, following two approaches to ethnographic fieldwork, as well as in-depth interviews to collect data. In addition, the perspective of community approaching was applied in conducting the research. This perspective is to help the researcher assesses the current situation, and shows the direction of development for this community and others.

Study on the relationship between total dissolved solids (TDS) and electrical conductivity (EC) of the aquifers in Ca Mau province

This article has established a set of empirical equations to describe the relationship between bulk resistivity and TDS of the Upper-Middle Pleistocene aquifer (qp2-3) and Lower Pleistocene aquifer (qp1) of the for field survey in 2017 in Ca Mau province. This article has determined the content of TDS based on EC (TDSEC) and established correlation regression equation between TDSLAB and TDS is based on the EC of the qp2-3 aquifer: Y = 0.549X – 0.081 with R2 = 0.975 and Standard Error (SE) = 0.1591. The qp1 aquifer: Y = 0.4669X + 0.0483 with R2 = 0.9869, Standard Error (SE) = 0.0949. Based on these regression correlation equations, we found a high correlation coefficient and small deviation between TDSLAB and TDSEC. Therefore, the determination of TDS content through the EC has reduced the cost of groundwater samples of the aquifers of laboratory analysis in Ca Mau province.

Factors driving low oxygen conditions in integrated rice-shrimp ponds

Integrated rice-shrimp ponds (IRSPs) are common in areas of Southeast Asia where saltwater intrudes into rice fields in the dry season, enabling rice production in the wet season, and shrimp farming in the dry season or throughout the year. Previous research has highlighted that IRSPs have periods of low dissolved oxygen concentrations which may have a critical effect on shrimp survival. To understand the causes of low dissolved oxygen, this study examined oxygen fluxes at two IRSPs in Ca Mau Province, Vietnam during a two-year period (two wet seasons and two dry seasons). Sediment oxygen demand (SOD) incubations and whole-system oxygen flux measurements were conducted and compared with a range of water and sediment parameters to explain drivers for low oxygen concentrations. A high percentage of oxygen demand at a whole pond scale was from the sediment; hence SOD drove low oxygen concentrations in the water column. SOD rates were significantly positively correlated with chlorophyll a concentrations in the water column. These findings suggested that algal production in the water column, rather than benthic algal production, or other organic loading, provided an organic carbon source driving SOD. Oxygen demand was much higher than oxygen production within the IRSPs, indicating high bacterial activity and low algal production. This study has shed new light on the importance of SOD in driving oxygen drawdown in IRSPs and improving shrimp survival requires new management approaches to reduce the negative effect of SOD.

Assessment of the ecological quality status of sediment at the organic shrimp farming ponds in Ca Mau province by applying the abundance/biomass comparison (ABC) method on nematode communities

Nematode communities in the Tam Giang’s organic shrimp farming ponds, Nam Can district, Ca Mau province were investigated in three seasons (March - dry, July - transfer and November - rainy season). Results showed that the average abundance (inds/10 cm2) ranged from 221.67 ± 122.08 to 2539.33 ± 1403.33 in the dry season. The tranfers and rainy season also showed a high density, from 1020.00 ± 354.30 to 7254.67 ± 5454.39, 822.00 ± 1086.17 – 4608.33 ± 1302.02, respectively. Total dry biomass (µg/10 cm2) of nematode communities in Tam Giang’s organic shrimp farming ponds varied from 51.11 ± 28.64 to 450.87 ± 49.53 in the dry, from 412.93 ± 291.87 to 1607.25 ± 507.42 in the transfer and ranged 49.54 ± 39.36 to 1874.09 ± 3033.16 in the rainy season. The following results were also recorded that abundance/biomass comparison (ABC) method has been used successfully for detecting the ecological quality status of sediment (EcoQ) in Tam Giang’s organic shrimp farming ponds. The results indicated that unfavourable deflections (stress) in EcoQ of Tam Giang’s organic shrimp farming ponds throughout the dry - transfer - rainy season. More specifically, the EcoQ of Tam Giang’s organic shrimp farming ponds has been classified as lightly stressed in most seasons, excpet for the transfer season which has been recognized as the highest EcoQ depending on its ABC curves and W values. Although EcoQ in the Tam Giang’s organic shrimp farming ponds has always been clear, information on Received 05-01-2017, accepted 14-08- 2017, published 12- 9-2018 Author: Tran Thanh Thai, Nguyen Thi My Yen, Ngo Xuan Quang- Department of Environmental Management and Technology, Institute of Tropical Biology, Vietnam Academy of Science and Technology, Le Dieu Linh - Ton Duc Thang University - thanhthai.bentrect@gmail.com the main cause effected biomass between natural stress or pollution stress remains uncertain.

Pull factors influencing tourist perception in rural tourism: The case study of Ca Mau province, Viet Nam

This quantitative study identifie factors affecting tourist perception in the context of rural tourism in Ca Mau province – the southernmost province of Vietnam, belonging to the Mekong Delta. In which, local culture, infrastructure and marketing communication has positive relation with tourist perception, while services &amp; entertainment has negative relation. The research produced 400 structured questionnaires to collect data on these factors in Ca Mau, and found that there is a significant influence on tourist perception in rural tourism sector, which 58% changing in tourist perception is explained by the independent variables. The regression equation is set as: Y = 1.423 + 0.343X1 – 0.082X2 + 0.273X3 + 0.189X4 (Y= Tourist Perception; X1= Local Culture; X2= Services &amp; Entertainment; X3= Infrastructure; X4= Marketing communication)

The Seasonal Variability in The Genus-Family Structure of Free-Living Nematode Communities in Organic Shrimp Farming Ponds, Ca Mau Province

The Seasonal Variability in The Genus-Family Structure of Free-Living Nematode Communities in Organic Shrimp Farming Ponds, Ca Mau Province

Đánh giá hoạt động ghi chép và lưu trữ thông tin theo tiêu chuẩn Global GAP của những nông hộ nuôi tôm sú (Penaeus monodon) tại tỉnh Cà Mau

This study aims to assess the information recording and keeping activities based on the framework of Global GAP standards. An investigation was conducted on 85 black tiger shrimp (Penaeus monodon) farms in Dam Doi district, Cai Nuoc district and Ca Mau city (Ca Mau province). Descriptive statistics and independent samples T-test were employed to analyse and compare the differences in financial effieciency between farms with and without information management. The main results were summarised as follows: Despite the fact that Global GAP was an essential certificate to meet the requirement of global markets, shrimp farmers in Ca Mau did not pay much attention to its criteria, especially the criteria of recording and keeping information in order to satisfy the traceability requirements. The information management actitivities enhanced the farm efficiency of shrimp farms based on the comparison’s results of financial indices between shrimp farms with and without information management. The results of this study were considered to emphaisize the necessity of the Global GAP standards application for local shrimp farms.

Xác định các dịch vụ hệ sinh thái của hệ sinh thái rừng tràm ở vùng đệm Vườn Quốc gia U Minh Hạ - Cà Mau

This study is aimed to evaluate ecosystem services in the buffer zone of the National Park of U Minh Ha, Ca Mau province. One hundred and twenty households representing four cultivating models including intensive cultivation of Acacia hybrid and Melaleuca cajuputy, two rice crops, and integrated rice-shrimp were interviewed for the direct and indirect benefits supporting local people’s livelihoods in order to control and harvest the forest’s production as well as to maintain this natural resources concurrently. The overall results showed that provisioning services, regulating services and supporting services were the most important evaluation form those models (scored 5) accounting for 46.8%, 28.13%, and 25%, respectively whereas cultural services get no ideas for evaluation (0%). In this scope, it is necessary to identify Melaleuca ecosystem services under perception of different local stakeholders, in order for the local government to have a closer look on the common benefits among multi-stakeholders depending on Melaleuca forest, and thus to apply more appropriate strategies to conserve this ecosystem services such as ecotourism activities, scientific research enhancement.

Free living nematode communities as fundamental food for shrimps in the ecological - model of mangrove - shrimp farming ponds, Nam Can district, Ca Mau province

Free-living nematodes were investigated in order to understand as the natural food for shirmp in the model of ecological mangrove – shirmp farm in mangroves forest according to their composition and densities by seasonal changes. Twenty – four samples of free living nematodes were collected in 8 ecological shrimp ponds (three replicate per pond) in 4 hamlets of Tam Giang commune, Nam Can district, Ca Mau province. Three sampling campaigns were carried out during dry, transitional and rainy seasons in year 2015. In total of 111 nematode genera, 32 families, 10 orders belong to 2 classes of free living nematodes were identified in these mangrove shrimp ponds. Nematode genera richness were quite high, and significant different among three sampling times while their density in the rainy season was considerably higher than such of the dry season. Some genera Pseudolella, Dichronema, Gomphionema, Ponponema, Halalaimus, Sphaerotheristus, Eumorpholaimus, Euleutherolaimus, Parodontophora, Ptycholaimellus, and Sabatieria were typical in these mangrove areas. Especially, two genera Daptonema and Terschellingia develop dominantly in 3 sampling campaigns. Additionally, a significant number of nematode genera were found in all sampling times whereas some other genera only represent in one season. Desities of nematode communities were recognised rather high. Average densities and standard deviation in each mangrove shrimp ponds ranged from 222 ± 122 (individual / 10 cm2) to 7255 ± 5454 (individual / 10 cm2). These characteristic of free living nematode communities in the ecological model of mangrove - shirmp ponds might provide suitable natural food source for shirmps and enrich the benthic foodweb.

Microhabitat selection and communal nesting in the insular Psychedelic Rock Gecko, Cnemaspis psychedelica, in Southern Vietnam with updated information on trade

The Psychedelic Rock Gecko,Cnemaspispsychedelica, was described in 2010 and certainly belongs to the most spectacular gecko discoveries worldwide. The species is endemic to two small offshore islands in Rach Gia Bay. Its striking colour pattern makes the species highly attractive for the international pet market. The existentCnemaspispopulation is negatively affected by habitat degradation and predation by introduced macaques. We herein provide the first characterisation of microhabitat selection of this species, including seasonal variation on Hon Khoai and Hon Tuong islands, Ca Mau Province, Vietnam. We found that characteristics of the selected microhabitat, such as substrate type, temperature and canopy cover slightly differed between the wet and dry seasons. We also demonstrated age-related differences in the selection of perch heights. Communal nesting was, for the first time, reported forC.psychedelica, as well as natural predation by a snake species (Lycodoncapucinus). In addition, we documented ongoing habitat destruction on Hon Khoai Island and recorded illegal trade of live Psychedelic Rock Geckos for the first time on local pet markets in both northern and southern Vietnam. Our findings highlight the need for improved conservation measures in order to reduce anthropogenic impacts on wild populations ofC.psychedelica.

EFFECTS OF NITROGEN AND POTASSSIUM LEVELS ON GROWTH, YIELD AND QUALITY OF BON BON (CATTAIL) IN CA MAU PROVINCE

The experimental layout was designed in completely randomized complete block with 4 replicates in the combination of nitrogen levels of 28,8; 60; 90; 120 kg/ha with potassium of 0 and 30 kg/ha in order to investigate the effects of fertilization on growth, yield and quality of bon bon (Cattail) in Ca Mau province. At 90days after planting, treatments with higher levels of nitrogen application increased in plant height, tiller number, weight of edible part, fresh and dry biomass. Variations in nitrogen and potassium levels caused no change in photosynthetic pigments but chlorophyll a content was always about more than triple more than that of chlorophyll b. Potassium contributed to enhancinge plant height, biomass, edible part weight but difference in tiller number was not found between the two levels. Higher levels of nitrogen in combination with potassium not only enhanced biomass yield but also improved quality by increasing levels of soluble sugars and protein in the edible part. The interactions between nitrogen and potassium levels were recognizedpositively affected on growth, yield, and quality of cattail; therefore, it is highly recommended to apply both these nutrients when growing this crop.

Seasonal changes of reproductive cycle and proximate compositions in Cerithidea obtusa from Ca Mau mangrove forest, Vietnam

The present study investigated seasonal changes in gonad development and proximate compositions of the mangrove snail, Cerithidea obtusa in the mangrove forest of Ca Mau province, Mekong Delta of Vietnam.