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

Thesis 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.

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: 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: Reviewer 2: Reviewer 3: 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 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 OBJECTIVES To have the knowleadge of the nematode fauna from Perciformes fishes in the sea off Vietnam 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 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 THE THESIS STRUCTURE The thesis consists of 150 pages, in which: Introduction pages; Literature review 20 pages; Materials and research methods 13 pages; Results and Discussions 104 pages; Conclusion and Suggestions page The published works, which are related to the thesis page; References 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 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 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, supperfamilies, orders and 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) 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 nematoda species Akhtar et al (2006) recorded families, 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 nematode species of 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 have discovered and described 42 new species, including one species of Nematoda Le Van Hoa et al (1972), the first Vietnamese parasitologists, described new Bulbocephalus species from Thread finfish Hà Duy Ngọ et al (2009) found 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, nematode species were listed Nguyen Van Ha (2011) described a new species Ascarophis moraveci from 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 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 Time of the study: from 10/2014 to 12/2017 2.1.3 Places of study: Nine provinces of coastal regions in Vietnam (Figure 1) 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 studied by using phestin 6,67 Intestin 3,03 7-12 Intestin 1,27 1;3 Sargocentron melanospilos ** Stom 2/8 5;9 x Epinephelus retouti ** Stom 7,14 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 1-7 Pennahia argentata Intestin 10,34 1-5 x Priacanthus hamrur ** Intestin 15,25 1-28 x Intestin 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 2-5 x 15 3.2 The Classification of nematodes from Perciformes fishes in the off Vietnam - General characters of classes, orders, 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 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 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 nematode species Similarly, the number of fish species infecting by 2, 3, nematode species were 26 (29,21%), (10,11%), and (3,38%), respectively 23 CONCLUSIONS AND RECOMMENDATIONS CONCLUSIONS The study 3735 individuals of 129 fish species, 38 families of Perciformes has identified Thirdty seven nematode species belonging to classes, orders, 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 The specialization of nematodes in their hosts (Perciformes) is quite high, e.g 19 (51.35%) nematode species were foundfrom fish species, 18 (48,65%) remained species have or more hosts species The proportion of nematode species in their order, family, genus (18.5 species / order; 4.11 species / family; 1.76 species / genus) The highest proportion is found in Rhabditida (97.30%, 36 species) Contrarily, the lowest proportion is found in Trichinellida (2.70%, species) 37 (100%) nematode species were found from bottomdwelling fishes while only (18.92%) were found from fish living in surface of the water The prevalence of common nematode is 22.09%, the intensity of infection is - 148 worms/fish with a total of 7951 nematodes, including 2717 adult nematodes and 5234 larvae nematodes RECOMMENDATIONS Thirteen unidentified nematode species should be collected more samples for comparing morphological characters and molecular analyzing 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 24 LIST OF PUBLICATIONS 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 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 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 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 ... 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... 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