Summary of biology doctoral thesis: Nematode species component in some perciformes fishes in coastal regions of Viet Nam

MINISTRY OF EDUCATION
AND TRAINING

VIETNAM ACADEMY OF
SCIENCE AND TECHNOLOGY

GRADUATE UNIVERSITY SCIENCE AND TECHNOLOGY
----------------------------

HOANG VAN HIEN

NEMATODE SPECIES COMPONENT
IN SOME PERCIFORMES FISHES
IN COASTAL REGIONS OF VIET NAM
Major: Parasitology
Code: 9 42 01 05

SUMMARY OF BIOLOGY DOCTORAL THESIS

HA NOI - 2019


The thesis is completed at:
GRADUATE UNIVERSITY SCIENCE AND TECHNOLOGY
VIETNAM ACADEMI OF SCIENCE AND TECHNOLOGY

Supervisors:
1: Ass. Prof. Dr. Ha Duy Ngo
2: Dr. Nguyen Van Duc

Reviewer 1:........................................................................

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Reviewer 2:........................................................................
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Reviewer 3:........................................................................
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The dorteral thesis will be defended at the Evaluation Committee of:
GRADUATE UNIVERSITY SCIENCE AND TECHNOLOGY
Time: Date......month.......2019

The thesis can be found at:
- The library of Graduate University Science and Technology
- National Library of Vietnam


INTRODUCTION
1. THE THESIS NECESSARY
The risks of fish parasites, especially nematodes, to human
and animal health constitute are an important problems. The
infections are not only caused health deficiency or disability of
humans and animals but also reduce productivity and
profitability of aquacultute, increase economic burden due to
the costs for disease treatment and prevention. Although
parasitic deseases caused many harmfulness, they have received
little attention from scientists, managements.
Our study of the composition of the parasitic nematodes in
marine fishes in the off Vietnam is urgently needed. The
survey’s results are not only provide the information about the
fauna of fish’s nematoda, the relation between hosts-parasites,
but also assess the the potential risks for human consumption.
2. OBJECTIVES

To have the knowleadge of the nematode fauna from
Perciformes fishes in the sea off Vietnam.
3. THE RESEARCH CONTENTS
* To study and build the systematic of nematode fauna from
Perciformes fishes in the off Vietnam.
* To describe the morphological features of some selected
nematode species.
* To know the current status of nematode infections
(prevalence, intensity of infection) in some Perciformes fish
species (Perciformes) in the off Vietnam.

1


4. THE SCIENTIFIC AND PRACTICE SIGNIFICANCE
OF THE THESIS
- Providing the composition and the distribution of the
parasitic nematodes from Perciformes fishes in the off
Vietnam,, including a new records of host species. Especially,,
19 nematode species were found and described for the first time
in Vietnam.
- Providing the morphological data (measurement, drawings
and images, classification system) of all nematode species
which were collected in this study.
- Contributing the data of parasitic nematodes for the book
"Fauna of Vietnam: Parasitic roundworm in Vietnamese marine
fishes" later.
5. THE THESIS STRUCTURE
The thesis consists of 150 pages, in which: Introduction
2 pages; Literature review 20 pages; Materials and research

methods 13 pages; Results and Discussions 104 pages;
Conclusion and Suggestions 1 page. The published works,
which are related to the thesis 1 page; References 9 pages,
include 13 documents in Vietnamese and 81 documents in the
foreign languages. The thesis has 11 tables, 47 figures and
illustrations, diagrams and 16 appendix pages.

I. Chapter 1. OVERVIEW
1.1. Basic characters of parasitic nematodes: General
morphological features, biological characters, life cycle of
nematodes, the distribution and harmfull effects of nematodes
were provided.

2


1.2. Summary of the parasitic roundworm classification
system: The outline of the nematode classification system in
the World and Vietnam were summarized.
1.3. Some basic characters of the Vietnamese marine fish
fauna, including the Perciformes order: General characters of
marine fish fauna in Vietnam, especially fishes belong to
Perciformes order were mentioned.
1.4. The studying situation of parasitic nematodes in marine
fishes.
1.4.1. Research on parasitic nematodes in marine fishes in
the Western Pacific region
Research on parasitic helminths in marine animals has been
conducted since the late 19th century, but it was received more
attention by scientists from the miStole of the 20th century.

Particularly, the data of nematode fauna from the Western
Pacific region has been avaiable about three late decades.
Wu (1927) had the first report of parasitic nematode from
marine fish in the off China, the author described one nematode
species

Paraleptus

scyllii

from

sharkes

Chiloscyllium

plagiosum in Taiwan sea . Up to 1965, Chinese scientists
continued to investigate the parasite fauna from marine fishesin
this region. In 2011, Peng et al. listed a total of 90 species of
nematodes

belonging

to

31

genera,

13

families,

9

supperfamilies, 3 orders and 2 subclasses in marine fishes in
China. However, this list already included all species (19
nematode spcies) which were found by scientists from Vietnam
and the former Soviet Union in the East Sea of Vietnam (South
China Sea).

3


Arthur et al. (1997) listed 201 parasitic species in Philippine
fishes, including 20 species of nematoda. In this list has
presented of Capillaria philippinensis, which can infecting to
human.
In Thailand, Purivirojkul (2004) found 11 nematode species
from marine fishes.
Jakob et al. (2006) identified 38 helminthic species in
marine fish in Java Island, Indonesia; including 5 nematoda
species.
Akhtar et al. (2006) recorded 7 families, 9 subfamilies, 23
genera and 71 species of nematoda from fishes in the off
Pakistan. Later, Kazmi et al. (2013) listed 90 nematode species
in whole country.
In Japan, studies on parasitic helminths in marine fish were
early carried out, e.g. Layman (1930)found the species
Capillaria helenae. Recently, Nagasawa et al. (2007) identified

7 nematode species of 7 genera.
Arthur et al. (2015) has recorded 24 species of nematode
parasites in fish in the off Malaysia. Almost species were
identified to genus.
1.4.2. The studying situation of parasitic nematode from
marine fishes in Vietnam.
Research on the system of the parasitic helminth from
marine fishes in Vietnam has only been carried out after 1960.
The Russian scientists autopsied 1,118 individuals of 53 fish
species, 16 families from the off East Sea. Among them, 888
individuals of 44 species belong to Perciformes. The authors

4


have discovered and described 42 new species, including one
species of Nematoda.
Le Van Hoa et al. (1972), the first Vietnamese
parasitologists, described 2 new Bulbocephalus species from
Thread finfish.
Hà Duy Ngọ et al. (2009) found 2 nematode species genera
Capillaria and Anisakis in the off Ha Long, Quang Ninh
Province.
Vo The Dung (2010) detected 54 parasitic species from the
grouper Epinephelus spp. in the off Nha Trang, Khanh Hoa
province, including 34 identified species and 20 other
unidentified species. Especially, 8 nematode species were listed.
Nguyen Van Ha (2011) described a new species Ascarophis
moraveci from 3 fish species in the off Ha Long, Quang Ninh
province.

Dang Nguyen Anh Tuan et al. (2015) recorded a species
Camallanus sp. from Parupeneus spp. in off Nha Trang, Khanh
Hoa province.
Chapter 2. MATERIALS AND METHODS
2.1. Subjects, sites and time of the study
2.1.1. Subjects of the study
Subjects of this study were parasitic nematodes that
collected on from Perciformes marine fishes. .
2.1. 2. Time of the study: from 10/2014 to 12/2017
2.1.3. Places of study: Nine provinces of 3 coastal regions in
Vietnam (Figure 1)

5


Figure 1: Study sites
2.2. Study methods
Nematode

specimens

were

collected

by

using

a

“comprehensive examination” method of Skrjabin (1928).
Samples were fixed, and made slides by using a method of De
Grisse (1969). Morphological characters of nematodes were

6


studied by using phestin

6,67

1

Intestin

3,03

7-12

Intestin

1,27

1;3

Sargocentron
melanospilos **

Stom

2/8

5;9

x

Epinephelus retouti **

Stom

7,14

1

x

Dentex tumifrons **

Stom

20

2;3

x

Scatophagus argus

Stom

5,80

1-8

x

x

Nibea albiflora

Stom

22,45

2-17

x

x

x

x
x
x

Genus Raphidascaroides Yamaguti, 1941
14

R.nipponensis*
Yamaguti,1941

Dactyloptena orientalis
**

x

Familly Ascarididae Baird, 1853
Genus Porrocaecum Railliet & Henry, 1915
15

Porrocaecumsp.

Nimepterus Japonicus **

x

Familly Quimperiidae (Gendre, 1928) Baylis, 1930
Genus Haplonema Ward & Magath, 1917
16

Haplonema sp*.

Terapon jarbua **

x

x

Familly Cystidicolidae Skrjabin, 1946
Genus Ascarophis Van Beneden, 1871

17

18

Ascarophis sp.

A. moraveci Ha et
al., 2011

Genus Spinitectus Fourment, 1883

14


19

S. echenei
Parukhin, 1967

Coryphaena hippurus **

Intestin

3/5

2-9

x

Stomuch

15,52

1-5

x

Stomuch

10,34

2-5

Intestin

6

1-7

Pennahia argentata

Intestin

10,34

1-5

x

Priacanthus hamrur **

Intestin

15,25

1-28

x

Intestin

4

1

x

x

Auxis thazard

**

Genus Prospinitectus Petter, 1979
20

Prospinitectus

mollis (Mamaev,
1968) Petter, 1979

Auxis thazard

x

x

Familly Philometridae Baylis & Daubney, 1926
Genus Buckleyella Rasheed, 1963
21

B. buckleyi
Rasheed, 1963

Jhonius carouna**

x

Genus Philometra Costa, 1845
22

P. scieanae*
Yamaguti, 1941

Genus Philometroides Yamaguti, 1935
P. atropi
(Parukhin, 1966)
Scomberoides

23
Moravec &
commersonianus **
Ergens, 1970
Familly Camallanidae Railliet et Henry, 1915
Genus Camallanus Railliet & Henry, 1915
Camallanus
carangis Olsen,
1954

Carangoides malabaricus

Intestin

5,48

4-9

24

Atule mate **

Stomuch

13,33

2;5

x

25

Camallanus sp.

Jhonius carouna **

Intestin

7

2-5

x

15


Nemipterus hexodon **

Intestin

14,29

1-8

x

Genus Procamallanus Baylis, 1923
26

P.annulatus*Yamaguti,
1955

Siganus guttatus **

Stomuch

11,76

1;1

x

27

P.laeviconchus*Wedl,
1862

Siganus virgatus **

Stomuch

2,86

2

x

Leiognathus splendens **

Intestin

8

4-22

Lateolabrax japonicus **

Intestin

16

3-8

x

Epinephelus retouti **

Intestin

7,14

7

x

1-15

x

Genus Procamallanus Baylis, 1923
Subgenus Procamallanus (Spirocamallanus) Olsen, 1952
28

P. (Spirocamallanus)
spiralis* Baylis,
1923

29

P.(Spirocamallanus)
guttatusi
Andrade-Salas,
Pineda-Lopez et
Garcia-Magana, 1994

x

30

P.( Spirocamallanus)
pereirai*
Annereaux, 1946

Otolithes ruber

Intestin

31

P.( Spirocamallanus)
dussumieri*
Bilqees, Khanum
& Jehan, 1971

Jhonius carouna **

Intestin

32

P.(Spirocamallanus)sp.*

Cephalopholis miniata

Intestin

2/5

2;4

x

Lethrinus miniatus

Intestin

18,18

3;3

x

4,08

6

16

1-8

x

x


Familly Cucullanidae Cobbold, 1864
Genus Cucullanus Muller, 1777
33

C.heterochrous
Rudolphi, 1802

Scatophagus argus **
Pomadasys maculatus

34

C.rastrelligeri*
ThanaponY.,Moravec

F.,ChalobolW.,2011

**

Stomuch

10,14

3-21

x

Intestin

1,67

3

x

Sargocentron melanospilos **

Intestin

3/8

1-37

x

Sargocentron rubrum **

Intestin

1/8

4

x

Intestin

3,39

1-11

Siganus fuscescens

**

35

Cucullanus
(Truttaedacnitis)
Truttae*Fabricius,1794

Nibea albiflora **

Intestin

24,49

2-13

36

Cucullanus
(Cucullanus)***sp.

Jhonius carouna

Intestin

10

2-14

Intestin

11,54

3-12

x
x

x

x

x

Genus Dichelyne Jagerskiold, 1902
37

Dichelyne sp.

Jhonius belangerii **

x

Note: * Nematode species was the first recorded in Vietnam; ** New host species; *** Maybe a new nematode species.

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3.2. The Classification of nematodes from Perciformes fishes
in the off Vietnam.
- General characters of 2 classes, 2 orders, 9 familly and 21
genera of nematodes in this study were provided.
- 37 nematode species from Perciformes fishes were described.
Other relevant issues of the described species were also
commented, e.g. historical and differentiating characters, the
different characters from the original description of the species
and other close species in the common genus.
- Providing a classification key for some nematode species
which were collected in this study.
- Using both molecular and morphological techniques to
identify Anisakis typica.
3.3. The prevalence and intensity of nematode infection

from Perciformes fishes in the off Vietnam.
3.3.1. The prevalence of nematode infection by fish families
There are 32 out of 38 fish families infected with nematodes;
other 6 families have no infection .

Figure 3.38: The prevalence of nematode infection by fish families
3.3.2. The prevalence of nematode infection by fish species
A total of 3735 individuals of 129 fish species were
examined.
There were 825 individuals of 89 species infected by
nematodes, and thecommon infection was 22.09%.

18


3.3.3. The prevalence of nematode infection from Perciformes
fishes by coastal regions in Vietnam.
+ The prevalence of nematode infection by fish families at each
coastal region (number families of infected fish / number
families of examined fish examinations at each coastal region).

Figure 3.39: The prevalence of nematode infection by fish
families in different coastal regions
+ The infection rate of nematodes by fish species (number of
infected fishes/ number of each examined fish species in
different coastal regions).

Figure 3.40: The infection rate of nematodes by fish species in
different coastal regions in Vietnam

19


+ The infection rate of nematodes in different coastal regions in
Vietnam (Number of infected fishes / number of examined
fishes in each coastal regions).

Figure 3.41: The infection rate of nematodes in different coastal
regions
+ The percentage of examined fishes in each coastal regions
(Number of examined fishes in each coastal region / A total of
examined fishes in this study)

Figure 3.42: The percentage of examined fishes by regions
+ The infection rate of nematodes by regions (Number of
infected fishes in each region / a total of examined fishes)

20


Figure 3.43: The infection rate of nematodes by the coastal
regions
3.3.4. The intensity of nematode infection from Perciformes
fishes in the off Vietnam
The intensity of nematode infection has a large range of
variability among fish families as well as fish species and even
among individuals of each species, e.g. Oysters 1-128 worms /
fish.
3.4. Several character of nematode fauna from Perciformes
The researches on parasitic nematodes from marine fishes

have are great importance because marine fish products have
increaasingly contributed to total aquaculture production. So,
the knowleadge of nematode fauna from marine fishes will help
exporters to control the risks of “fishborne zoonotic nematodes”
of their products.. However, researchs on nematode fauna were
less received attend of scientists and managers in Vietnam. In
this study, 37 nematode species were found in whole country.
Among them, the number of nematode species in the Northern,
Central and Southern coastal region were 15, 26, and 11,
respectively (Figure 3.44). The diversity of nematode fauna in
the Central coastal region is highest, and lowest in the Southern
coastal region.

21


Figure 3.44: The number of nematode species collected in the seas

Figure 3.45 : Characteristics of nematode distribution in Vietnamese waters

22


Figure 3.46: The number of host of nematodes
Regarding to host-parasite relationship, 19 out of 37
(51,35%) nematode species parasitize in only one host species;
18 (48,65%) remained species have 2 or more hosts species
(Figure 3.46).

Figure 3.47: The number of nematode species in their host(s)

Among 89 infected fish species, 51 (57,30%) species were
infected by only 1 nematode species. Similarly, the number of
fish species infecting by 2, 3, 4 nematode species were 26
(29,21%), 9 (10,11%), and 3 (3,38%), respectively.

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CONCLUSIONS AND RECOMMENDATIONS
CONCLUSIONS
1. The study 3735 individuals of 129 fish species, 38
families of Perciformes has identified Thirdty seven
nematode species belonging to 2 classes, 2 orders, 9 familly
and 21 genera were identified, including 24 species have
been identified at species level, 13 species have been
identified at genus level . Especially, 19 species were the
first time found in Vietnam, 26 fish species are recorded as
new hosts for the nematode fauna.
2. The specialization of nematodes in their hosts
(Perciformes) is quite high, e.g. 19 (51.35%) nematode
species were foundfrom 1 fish species, 18 (48,65%)
remained species have 2 or more hosts species.
3. The proportion of nematode species in their order,
family, genus (18.5 species / 1 order; 4.11 species / 1 family;
1.76 species / 1 genus). The highest proportion is found in
Rhabditida (97.30%, 36 species). Contrarily, the lowest
proportion is found in Trichinellida (2.70%, 1 species).
4. 37 (100%) nematode species were found from bottomdwelling fishes while only 7 (18.92%) were found from fish
living in surface of the water.
5. The prevalence of common nematode is 22.09%, the

intensity of infection is 1 - 148 worms/fish with a total of
7951 nematodes, including 2717 adult nematodes and 5234
larvae nematodes.
RECOMMENDATIONS
1. Thirteen unidentified nematode species should be
collected more samples for comparing morphological
characters and molecular analyzing.
2. This study should be expanded to provide more data of
nematodes in different fish orders and updating the
knowleadge of nematode fauna from marine fishes in the off
Vietnam.

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LIST OF PUBLICATIONS
1. Hoang Van Hien, Nguyen Van Ha, Ha Duy Ngo, Nguyen
Van Duc, Primary research on parasitic nematodes in some
coastal marine fish of Quang Binh province, Vietnam Journal of
Agricultural Sciences, 2017, 15 (11), 1529-1538.
2. Hoang Van Hien, Ha Duy Ngo, Nguyen Van Ha, Nguyen
Van Duc, Research on parasitic nematodes in some coastal
marine fish of Khanh Hoa province, Science and Technology
Journal of Agriculture & Rural Development, 2018, 14, 70-77.
3. Hoang Van Hien, Ha Duy Ngo, Nguyen Van Ha, Nguyen
Van Duc, Bui Thi Dung, Investigation on nematode species
composition of perciformes in coastal reigion Hai Phong
province, Publishing House for Science and Technology, 2017,
170-175.
4. Hoang Van Hien, Bui Thi Dung, Ha Duy Ngo, Nguyen Van

Ha, Nguyen Van Duc, A Preliminary investigation on nematode
species composition of the snake eels (Ophichthidae:
Pisodonophis) in coastal reigion Nam Dinh province,
Publishing House for Science and Technology, 2015, 126-132.