Seaweed diversity in Vietnam, with an emphasis on the brown algal genus Sargassum

199 Pages·2014·6.9 MB·English

Ghent University
Faculty of Sciences, Department of Biology
Phycology Research Group

Seaweed diversity in Vietnam, with an emphasis on
the brown algal genus Sargassum

by
Nguyen Van Tu

Promotor: Prof. Dr. Olivier De Clerck
Co-promotor: Prof. Dr. Bui Van Lai

Academic year 2014-2015

This thesis is submitted as a partial fulfillment of the requirements for the
degree of Doctor (PhD) in Science (Biology)
The thesis was completed with funding from the Belgian Technical Cooperation
under Grant VIE10/0020.
Examination committee
Promotor
Prof. Dr. Olivier De Clerck
Ghent University, Belgium
Members of the reading committee
Dr. Florence Rousseau
Muséum National d'Histoire Naturelle de Paris, France

Dr. Frederik Leliaert
Ghent University, Belgium

Dr. Kyung Min Lee
Ghent University, Belgium
Other members of the examination committee
Prof. Dr. Mieke Verbeken (Chair)
Ghent University, Belgium

Prof. Dr. Ann Vanreusel
Ghent University, Belgium

Prof. Dr. Patrick Sorgeloos
Ghent University, Belgium
Acknowledgements
First of all, I would like to express my gratitude to the Belgian Technical Cooperation, which
enabled me to pursue my studies at Ghent University (grant 10VIE/0020).
This thesis would not have been possible without the help and encouragement from my
supervisor Prof. Dr. Olivier De Clerck, who supported me from the application procedure
for the BTC Scholarship onward and continued to support me for four years. Prof. De Clerck
also guided me on the road of science and taught me a lot of skills which will be valuable
also for my future research. I am grateful to my co-supervisor Prof. Dr. Bui Van Lai, who
encouraged me to make this thesis happen.
I would also like to thank Prof. Dr. Nguyen Huu Dai who was so kind to share his Sargassum
knowledge with me, Dr. Le Nhu Hau for his support during field trips and Dr. Huynh Quang
Nang to open up phycology for me.
I am also sincerely thankful to all the member of the Phycology Research Group for their
generosity to share knowledge with me. Special thanks goes to Sofie D'hondt, Tine
Verstraete, who helped me with the molecular work, Kyung Min Lee, Frederique Steen,
Dimitris Zervas for their help with the Rad-Seq, Frederik Leliaert, Heroen Verbruggen,
Agnieszka Lipinska, Viviana Peña, Sofie Vranken, Kenny Bogaert and Andrea Del Cortona
for their interesting talks, and Samuel Bosch and Du Vu Viet Quan for the maps in chapter
1. I also thank Mrs. Christelle Vankerckhove and Anja Hondekyn for their help with the
administrative work. Many thanks to the members of Protistology and Aquatic Ecology
group, who made the work environment very friendly!
I am indebted to my colleagues in Vietnam to support me during field trips and data
management. Thanks to my Vietnamese friends in Ghent who made me happy and
stimulated me to think positive during the difficult times. I am indebted to numerous
people along the coast of Vietnam, who supported me during my field trips.
Of course no acknowledgments would be complete without giving thanks to my family, in
particular my parents, who supported me my entire life and in particular my times far from
home. They have always expressed how proud they are of me and how much they love me.
Last, but certainly not least, my tremendous and deep thanks goes to my son and wife.
Through their love, patience, support and unwavering belief in me, I have been able to
complete this long dissertation journey.
Thank you all!

Vietnamese names
Vietnamese names generally consist of three parts: a family name, a middle name, and
a given name, used in that order. Due to the ubiquity of the major family names such as
Nguyễn, Trần, and Lê, people are often referred to by their middle name along with their
given name in the Vietnamese media. This system conflicts with traditional scientific
author citations which are biased toward Western-style names. Thereto, in this thesis
Vietnamese authors are cited by their family name followed by the initials of their middle
and first names. For example, Pham Hoang Ho becomes Pham H.H. Diacritics, of which the
Vietnamese language uses nine marks to create additional sounds or to indicate
the tone of each word, are left out. If the combination of family name and initials of both
middle and first name are non-discriminatory, names are cited by family name followed by
the initial of the middle name and the entire first name. For example, Nguyen Huu Dai and
Nguyen Huu Dinh, are cited as Nguyen H. Dai and Nguyen H. Dinh, respectively.
CONTENTS
Chapter 1. General introduction and thesis outline ..................................................................1
Chapter 2. Checklist of the marine macroalgae of Vietnam ......................................................31
Chapter 3. Taxonomy and morphology of the genus Sargassum ..............................................69
Chapter 4. Sargassum diversity in Vietnam: a molecular phylogenetic approach ....................98
Chapter 5. Marker development for species delineation in the genus Sargassum based on
RAD-Sequencing ........................................................................................................................160
Chapter 6. General discussion ...................................................................................................177
SUMMARY .................................................................................................................................189
Chapter 1

General introduction and
thesis outline
General introduction and thesis outline
1.1 Vietnam: geography and climate
Vietnam is located in the Indo-West Pacific on the eastern margin of Indochinese Peninsula.
The mainland of Vietnam, extending from 8°27’ to 23°23’ N, is bordered by the East Sea and
the Gulf of Tonkin in the East and the gulf of Thailand in the South. The coastline of Vietnam
extends for 3260 km (excluding islands) and is characterized by a subtropical climate in the
North which gradually becomes fully tropical in the South. The coastline is dotted by
numerous islands, islets, atolls and reefs in ca. ~1.000.000 km² of sea area (Le B.T. 1998).
Because of its predominant North-South orientation, the coastal environment of Vietnam is
categorized by distinct zones based on meteorological, hydrological and geological
characteristics (Fig. 1.1). The physical and climatological characteristics of these zones may
differ significantly (Fig. 1.2). For example the North coast is dominated by river mouths and
deltas (Red River delta) interspersed by sandy beaches and only a limited amount of rocky
shores, while the Central coast is predominantly rocky. The South Central coast has many
atolls and islets of coralline origin. The South coast, however, is dominated by the Mekong
delta. Both the Red River in the North which discharges in the Gulf of Tonkin and the
Mekong in the South have a strong influence on the coastal topography (Vu T.L. 1978, Le
B.T. 1998). The influx of fresh water as well as the sediment carried by these rivers, renders
these environments largely unfavourable for the growth of marine macroalgae.
Vietnam lies in the East Asian monsoon zone. Two wind patterns dominate the coastline.
The winter monsoon coming from the northeast between October and March makes
winters relatively cold on the North, North Central and the Central coast, but dry and warm
on the South coast. From April-May to October the Southwest monsoon brings warm,
humid weather to the whole country. Between July and November, violent and
unpredictable typhoons often develop over the Pacific Ocean and often hit the Central and
Northern regions with devastating results. In southern Vietnam a wet and a dry season
alternate. The wet season lasts from May to November during which heavy but short-lived
downpours are a daily reality. The dry season usually runs from December to April. Much of
the precipitation in the coastal region is brought by the northeastern monsoon between
December and February (Pham N.T. and Phan T.D. 1993).

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Chapter 1

Fig. 1.1: Geographical location of Vietnam with indication of the various coastal zones.

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