PD Training


Project title: Effect of climate change on population dynamics of the swimming crab, Portunus pelagicus, and the epidemiology of selected disease causing organisms by PD Dang Thuy Binh

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Recent obtained results


Swimming crab, Portunus pelagicus was collected at Quang Ninh and Hai Phong (North of Vietnam), Khanh Hoa, Phu Yen (Center), and Phu Quoc, Ranh Gia -Kien Giang (south) from  5/2016 -5/2018.

Symbiotic community on swimming crab (P. pelagicus)

A total of 479 blue wild swimming crabs, Portunus pelagicus were collected from north to south along the Vietnam coastline. Symbiont species of the crabs were determined using morphological and genetic characters, and the temporal and spatial variation pattern in the symbiont were examined. A 17.95% of crabs were uninfected, 27.33% infected by 3-5 species, and 8.56% infected by more than 5 species. Among the 18 symbiont species found, 6 comprise a new host record. Crabs from the center of Vietnam had 17 symbiont species, those from the north had 12, and those from the south had 13. The most common symbionts were pedunculate barnacles, Octolasmis angulata, its congeners (O. warwickii and O. neptuni), and the protozoan ciliate, Zoothamnium chlamydis. The nemertean, Carcinonemertes mitsukurii and the copepod, Choniosphaera indica are well-known egg eating parasites. Verrillactis paguri and Electroma papilionacea were exclusively found in central Vietnam and Triticella flavar occurred in the north only. The most common symbionts differed in prevalence and intensity across geographic localities, and sex differences were found. Epistylis sp. and C. mitsukurii differed in prevalence and intensity in the two host sexes, whereas O. angulata and O. warwickii intensity and prevalence, respectively, differed. Prevalence and intensity was positively correlated with crab size for O. angulata and C. mitsukurii. Combined host features (distribution, sex and size) against symbiont diversity were also detected to be significantly different. Considering the host -symbiont associations, a PCA analysis did not show a clear connection between host features and symbiotic diversity.

Binh T. Dang, Sang Q. Tran, Oanh T.K. Le, Oanh T.T., Henrik Glenner (2018). Species diversity and phylogenetic relationships of symbiotic crustaceans on Portunus pelagicus (Linnaeus, 1758) in Vietnam, Proceedings of ISER 169th International Conference, Bangkok, Thailand, page 31-38, , ISBN 978-93-88350-68-6

Le Thi Kieu Oanh, Dang Thuy Binh, Tran Quang Sang (2018). Infestation status of the Pedunculate Barnacle (Octolasmis spp.) in blue Swimming Crabs (Portunus pelagicus Linnaeus, 1758) in Khanh Hoa, Journal of Malaria and Parasite Diseases Control, 104(2), page 93-98.

 Le Thi Kieu Oanh, Dang Thuy Binh, Tran Quang Sang (2018). Infestation status of epizoic Barnacle Octolasmis warwickii on Blue swimming crab Portunus pelagicus at Khanh Hoa and Phu Yen provinces, Journal of Tropical Science and Technology, 15, pp. 34–41.

One MS under review

Cophylogenies of Swimming crab (P. pelagicus) and dominant symbiotic species (Octolasmis angulata)

Comparative spatial structure and co-phylogenies of host populations with that of their symbionts can shed light on their evolutionary ineractions. The degree of congruence between host and symbiont phylogeographes should reflect to their life history, especially dispersal mechanisms. Here, we analysed the genetic diversity and structure of the host, the blue swimming crab, Portunus pelagicus, and its symbiotic pedunculate barnacle Octolasmis angulata from 6 location sites representing for three geographic regions (north, central and south) along the Vietnam coastline. Highly congruence in their phylogeographic patterns was expected as they both undergoes planktonic larval stages. Based on COI ntDNA markers, O. angulata populations showed the higher genetic diversity in computation to their hosts P. pelagicus (number of haplotype/individuals, haplotype and nucleotide diversity are 119/192, 0.991±0.002 and 0.02; and 89/160, 0.913±0.02 and 0.015, respectively). Pairwise Fst and AMOVA analyses showed more pronounced population structure in the symbiotic barnacle than its crab host. DAPC analyses detected three genetic clusters, however, both haplotype networks and scatter plots supported widely connectivity of host and symbiotic barnacle throughout their distribution range. Isolation by distance were detected only for symbiotic O. angulata (R2=0.332, P=0.05). Co-phylogenetic analysis did showed genetic congruent only when specific geographical host-symbiont links were examined.  In this association, the contrasted well mixing and genetic divergent among populations of host and symbiont, as well as significant co-occurring indications may provide the insight for host–symbiont co-evolution in the context of their spatial distributions.

Waitng for supervisor review

Population genetics of P. pelagicus in Vietnam

The blue swimming crab (Portunus pelagicus Linnaeus, 1758) is one of the commercially exploited crab fishery resources in Vietnam. This is the first study to provide a broad survey of genetic diversity, population structure and migration patterns of P. pelagicus along the Vietnamese coastline. The crab samples were collected from northern, central and southern Vietnam. Here, we used a panel of single nucleotide polymorphisms (SNPs) generated from restriction site-associated DNA sequencing (RADseq). After removing 32 outlier loci, 306 putatively neutral SNPs from 96 individuals were used to assess fine-scale population structure of blue swimming crab. The mean observed heterozygosity (Ho) and expected heterozygosity (He) per locus was 0.196 and 0.223, respectively. Pairwise Fst and hierarchical AMOVA supported significant differentiation of central and northern from southern populations (P<0.01). Population structure analyses revealed that P. pelagicus in the south is a separate fisheries unit from the north and center. Contemporary migration patterns supported high migration between northern and central populations and restricted genetic exchange within the southern population. In contrast, historic gene flow provides strong evidence for single panmictic population. The results are useful for understanding current status of P. pelagicus in the wild under an environment changing due to natural and anthropogenic stresses, with implications for fisheries management.

Dang BT, Rahman MA, Tran SQ, Glenner H (2019) Genome-wide SNP analyses reveal population structure of Portunus pelagicus along Vietnam coastline. PLoS ONE 14(11): e0224473. https://doi.org/10.1371/journal.pone.0224473

Education and Conference presentation

Based on the recently obtained results, our students have presented at

The Young Conference on Biotechnology and Environment held in Nha Trang University, 16 May, 2016. The title as follow:

1)  Preleminary results on population genetics of barnacle (Octolasmis angulata) infected swimming crab (Portunus pelagicus) at Khanh Hoa (Nghiên cứu bước đầu  về đa dạng di truyền quần thể giáp xác chân tơ (Octolasmis angulata) ký sinh trên ghẹ xanh (Portunus pelagicus) ở Khánh Hòa)

2)  Species diversity of barnacle species infected swimming crab (Portunus pelagicus) at Khanh Hoa  (Thành phần các loài giáp xác chân tơ (Octolasmis spp.) ký sinh trên ghẹ xanh (Portunus pelagicus) tại Khánh Hòa)

The International Conference on Conservation genetics on Mekong Delta Basin

3)   Symbiont diversity of swimming crab (Portunus pelagicus) in different temperature regimes in Vietnam

2 Master students have been graduated

- Muhammad Arifur Rahman (2018):  Master of Ecosystem based management and Climate change, Nha Trang University

- Le Thi Kieu Oanh (2017): Master of Biotechnology, Nha Trang University

Upcomming activities

The PD is scheduled to attend an international conference in early 2020, however, due to the covid 19 pandemic, the conference has been postponed, and the timeline has not been determined.


Research topic: Marine biodiversity loss and climate change: economic evaluation and implications for adaptation strategies - evidence from Vietnam by Quach Thi Khanh Ngoc
–Expected papers:
Paper 1: Economic evaluation of marine biodiversity loss linked to climate change: evidence from Vietnam.
Paper 2: Adaptation strategies for climate change impact on marine biodiversity , the case of Vietnam.

In 2017, Dr. Quach Thi Khanh Ngoc participated in different conferences in Singapore, Indonesia and Australia that helped her to present her works. In August, she presented her work funded by NORHED at the 7th Congress of the East Asian Association of Environmental and Resource Economics (EAAERE) “Environment and Sustainable Development: Issues, Challenges, and Solutions" in Singapore. She has gotten fresh perspectives on the research related to natural resources and climate change from this Congress.

            In November, she was invited to present her work on the climate change impact on coral reef ecosystem at the 3rd Monash Environmental Workshop in Australia. She has received valuable comments and suggestions for her paper from environmental economists from Australia, UK and US.

            Under the funding of UK research council, Ngoc also attended the workshop held in Indonesia: UK – Southeast Asia Researcher networking: Understanding the impact of hydrometeorological hazards in Southeast Asia. This workshop helps her to set up research network, and to share and to develop her research ideas.

            The funding of NORHED project bring her good opportunities for career development. She has one paper accepted in Marine Policy and has been revising another paper to resubmit to Ecosystem Services. 

Project title: Studies on effect of temperature and methionine in diet on juvenile cobia (Rachycentron canadum)

Project objective: The objective of this project is test to what extent elevated water temperatures increase the requirement for dietary methionine in juvenile cobia aquaculture.

Specific objective: The main objective of the present study is test to what extent elevated water temperatures increases the requirements for dietary methionine in cobia. The applied aspect is to generate the data that permits to maximize growth and N-retention in cobia. This will be done in two series of experiments with groups of cobia (juveniles) using different levels of dietary methionine and different temperature conditions.


Methods: Details for methods have already presented in the approved research proposal.

Time schedule: This project included two experiments and on a survey of a status of cobia culture in the South, Central and North of Vietnam. The first experiment was carried out from May to October 2016. The second experiment also was carried out between March and May 2017. The survey for a status of cobia culture has been done in the North, Central of Vietnam and the South of Vietnam between August and October 2017.


Activities have been done

Publications on ISI journal:

1. M.H Le, K.V. Dinh, M.V. Nguyen, I. Rønnestad. 2020. Combined effects of a simulated marine heatwave and an algal toxin on a tropical marine aquaculture fish cobia (Rachycentron canadum). Aquaculture Research. Manuscript accepted: 31 January 2020. Version of Record online: 13 March 2020. https://doi.org/10.1111/are.14596

2. M. Yúfera, M.V. Nguyen, C. Navarro-Guillén, F.J. Moyano, A.-E.O. Jordal, M. Espe, L.E.C. Conceição, S. Engrola, M.H. Le, I. Rønnestad. 2019. Effect of increased rearing temperature on digestive function in cobia early juvenile. Comparative Biochemistry and Physiology, Part A, 230:71–80. DOI:10.1016/j.cbpa.2019.01.007.

3. Nguyen, M.V., Espe, M., Conceição, L.E.C., Le, M.H., Yúfera M., Engrola, S., Jordal, A-E.O., Rønnestad, I. 2019. The role of dietary methionine concentrations on growth, metabolism and N-retention in cobia (Rachycentron canadum) at elevated water temperatures. Aquaculture Nutrition; 25:495–507. DOI: 10.1111/anu.12875.

Manuscript is working and will be submitted to journals before May/June, 2020:

1. M.H. Le, M. Espe, L.E.C. Conceição, M.V. Nguyen, M. Yúfera, S.A.D. Engrola, A-E.O. Jordal, I. Rønnestad. 2020. Impact of feeding rations on growth performance and N-metabolism of cobia (Rachycentron canadum) at elevated temperature.

Presented papers at conferences:

1.Yúfera, M., M.V. Nguyen, C. Navarro-Guillén, F. Javier Moyano, A-E.O. Jordal, M. Espe, L.E.C, Conceição, S. Engrola, M.H. Le, and I. Rønnestad. 2018. Effect of rearing temperature on the digestive function in Cobia fry. International Symposium of Fish Nutrition and Feeding, Las Palmas, Gran Canaria, Jun 3-7, 2018.

2.Navarro-Guillén, C., M.V. Nguyen, A-E.O. Jordal, M. Espe, L.E.C, Conceição, S. Engrola, M.H. Le, I. Rønnestad and M. Yúfera. 2018. Water temperature differentially affects food transit rates of stomach and intestine in Cobia fry. International Symposium of Fish Nutrition and Feeding, Las Palmas, Gran Canaria, Jun 3-7, 2018.

3.Nguyen, M.V., M. Espe, L. Conceição, M.H. Le, Yúfera, M., S. Engrola, A-E.O. Jordal, and I. Rønnestad. 2017. Growth, metabolism and N-retention in cobia at elevated water temperatures- the role of dietary methionine levels. Aquaculture Europe 2017, Dubrovnik, Croatia.

4.Nguyen, M.V., A-E.O. Jordal, M. Espe, L. Conceição, Yúfera, M., S. Engrola, M.H. Le, and I. Rønnestad. 2017. Feed intake and brain levels of appetite controlling neuropeptides in cobia is affected by elevated water temperatures. Aquaculture Europe 2017, Dubrovnik, Croatia.

5.Yúfera, M., M.V. Nguyen, S. Engrola, L. Conceição, A-E.O. Jordal, M.H. Le, M. Espe, P.Q. Hung, I. Rønnestad. 2016. Cobia exhibits a permanent gastric acidity as digestion strategy. Aquaculture Europe 2016 – Edinburgh, Scotland.


Supervised 01 master student in Aquaculture who has successfully defended her master thesis and graduated

Tentative Activities in 2020

Manuscript is working and will be submitted to journals before May/June, 2020: M.H. Le, M. Espe, L.E.C. Conceição, M.V. Nguyen, M. Yúfera, S.A.D. Engrola, A-E.O. Jordal, I. Rønnestad. 2020. Impact of feeding rations on growth performance and N-metabolism of cobia (Rachycentron canadum) at elevated temperature.

    • Effect of elevated water temperatures increase the requirement for dietary methionine on growth, body mass index, liver index, protein metabolism, lipid metabolism and feed efficiency cobia juveniles.
    • Effect of elevated water temperature increase the requirement for dietary methionine on feed intake, expression of NPY and CCK in juvenile cobia.
    • 01 Research proposal (done)
    • 01 Annual report and final report (done)
    • At least 01 paper will participate in the international conference (done)
    • At least 02 paper will be published in ISI journal
    1. The research proposal was approved by supervisor and rector of Nha Trang University.
    2. All experiment have been done. The publication related to Norhed project:
    1. Several pictures that related to the Norhed project.
    1. Budget                                                                                                                   - Scholarship used as following the research proposal (57,600NOK; 153,000,000 VND)                                                                                                             - Material and supply used as following the research proposal (205,608NOK; 546,900,000VND)                                                                                                                   -Tool and equipment used as following the research proposal (320,370NOK; 852,159,269VND)                                                                                                   Domestic travel used as following the research proposal (31,388NOK; 83,490,000VND)                                                                                                            - Data analysis used as following the research proposal (24,061NOK; 64,000,000VND)                                                                                                                    -  International travel will be transferred to University (43,200NOK; 114,908,544VND). Because I have no plan to use this money.
    1. Manuscript preparing for submitting to ISI journal which used the data from the second experiment.
    2. Submitting remained manuscript as first author to ISI journal, revising as following reviewers and journal.