ĐA DẠNG DI TRUYỀN QUẦN THỂ CÁ CHÌNH HOA (Anguilla marmorata) TẠI QUẢNG TRỊ

This study was conducted to evaluate the population genetic diversity of the wild Anguilla marmorata in Quang Tri province by comparing the DNA sequences of the mitochondrial control region (CR) gene with those of other giant mottled eel populations in the world. The results indicate that the genetic distance between individuals in the Quang Tri population ranged from 0 to 0.261, with an average of 0.024. Among 31 individuals, there were 203 distinct polymorphism sites (S), which led to 209 mutation sites (Eta) and 31 different haplotypes. The average number of distinct nucleotides (k) was 29,299. The nucleotide diversity factor (Pi) accounted for 26.09 × 10–3, and the minimum number of recombination processes (Rm) in the population was 51 events. The majority of eel samples collected at the site had close genetic relationships with those of the North Pacific population (27/31 individuals), and four eel samples had close genetic relationships with those of the South Pacific population. The finding of the four giant mottled eels in Quang Tri belonging to the South Pacific population is considered a significant result of this study.Nghiên cứu này được thực hiện nhằm đánh giá đa dạng di truyền của quần thể cá Chình hoa (Anguilla marmorata) tự nhiên tại tỉnh Quảng Trị dựa trên việc so sánh trình tự DNA của vùng gene điều khiển CR (control region) ty thể với các quần thể cá Chình hoa trên thế giới. Kết quả cho thấy khoảng cách di truyền giữa các cá thể trong quần thể dao động từ 0 đến 0,261, đạt trung bình 0,024. Trong 31 cá thể, 203 vị trí đa hình tách biệt (S) đã tạo ra 209 vị trí đột biến (Eta) với 31 kiểu haplotype khác nhau. Số lượng các nucleotide khác biệt trung bình là 29.299 (k); hệ số đa dạng nucleotide chiếm 26,09 × 10–3 (Pi); số lượng tối thiểu để xẩy ra quá trình tái tổ hợp (Rm) trong quần thể tương ứng với 51 sự kiện. Phần lớn cá thể thu được tại Quảng Trị có quan hệ di truyền gần gũi với quần thể cá Chình hoa Bắc Thái Bình Dương (27/31 cá thể) và 4 cá thể có mối quan hệ di truyền gần gũi với quần thể Nam Thái Bình Dương. Việc phát hiện các cá thể Chình hoa tại Quảng Trị có di truyền gần gũi với các cá thể thuộc Nam Thái Bình Dương được xem như một điểm đáng chú ý trong nghiên cứu này

Recruitment and genetic population genetics of spiny lobsters, Panulirus ornatus and P. homarus in the south-east Asian archipelago

Spiny lobsters are one of the world's most valuable seafood with high market value and where demand far exceeds supply. Accordingly, tropical spiny lobsters are a very valuable resource for most Southeast Asian countries, although populations of spiny lobsters in the region are currently subject to severe fishing pressure, primarily through the harvest of pueruli for aquaculture grow-out, which is considered a serious threat to the long-term sustainability of stocks. In 2004, a workshop was held at the Institute of Oceanography, Nha Trang, Vietnam, to discuss what was known about the ecology and exploitation of tropical spiny lobsters. This workshop identified several knowledge gaps that, at the time, were affecting the development of sustainable management policy for tropical spiny lobsters, including lack of information on genetic stock structure, where sink or source populations for recruiting larvae were located, and the comparative value of seed as stock recruits. With these knowledge gaps in mind, the overarching aim of the current thesis was designed to gain an increased understanding of recruitment patterns in two commercially important spiny lobsters, Panulirus ornatus and P. homarus, along with how populations of these two species were genetically structured across a wide range of their distribution. Particular focus was centered on Vietnamese stocks which were observed to exhibit large variations in recruitment prior to 2004. Chapter 2 first examined patterns in recruitment of the spiny lobster species Panulirus ornatus and P. homarus. Here long-term data that had been collected over six fishing seasons (2005 to 2011) on the abundance of juvenile seed (pueruli) caught by fishers along the central coast of Vietnam was coalesced.Recruitment data indicated large fluctuations in the monthly and annual pueruli catch of the two species of Panulirus, especially for P. ornatus. There was a similar pattern of spatial and temporal variation of total monthly catch in both species during the study period, with catch peaks occurring from November to the following February. The increase of total seed catch of P. ornatus was found to be highly correlated with that of southward wind stress(Exponential trendline; R² = 0.885, p-value < 0.05), suggesting that recruitment of P. ornatus could be predicted for the following season in Vietnam using wind stress as an indicator. This information would be useful to fishery managers, as it will allow them to predict the next season's likely scale of recruitment and the number of wild pueruli that could be sustainably harvested as aquaculture seed. To understand if spiny lobster recruits throughout the Indo-West Pacific originate from local stocks, or from a common widespread source, Chapters 3, 4 and 5 applied a population genetic approach to determine stock structure of P.ornatus and P. homarus. Genetic resources (mtDNA control region and nuclear microsatellite markers) were firstly developed in Chapter 3 and subsequently used to reveal the genetic structure of both species. Genetic analyses forP. ornatus (Chapter 4) showed no evidence for genetic differentiation among populations over thebroad and oceanographically complex region spanning Australia, Papua New Guinea, Indonesia and Vietnam (mtDNA control region sequences Φ(ST) = -0.008; microsatellite loci F(ST)= 0.003). A lack of evidence for regional or localized mtDNA haplotype clusters, or geographic clusters of microsatellite genotypes, reveals a pattern of high gene flow leading to panmixia in P. ornatus throughout the Indo-West Pacific. Based on biological and oceanographic data, a dispersal pathway of this species was developed to explain the genetic findings. Simulations incorporating known P. ornatus spawning areas, larval pelagic duration, and oceanographic data show that genetic homogeneity of P. ornatus can be explained by the oceanography-driven dispersal of the pelagic lobster larvae, which occurs from known spawning grounds in Papua New Guinea, the Philippines and, possibly, Indonesia. Results suggest the existence of a single panmictic population of P. ornatus in the Indo-West Pacific for conservation and fisheries management. In terms of P. homarus, the mtDNA control region analyses (Chapter 5) revealed moderate levels of genetic structure among populations(Φ(ST) = 5.31%; P < 0.05), whilst analyses atsix microsatellites detected significant genetic divergence between populations from Masirah, Oman, and several Southeast Asian Archipelago populations (Φ(ST) = 7.5% - 19.8%). Low levels of genetic structure were also observed within the Southeast Asian Archipelago. Bayesian individual assignment analysis based on microsatellites showed that lobsters from Masirah, Oman were more homogeneous to a single genetic cluster, which was not revealed by the mtDNA, suggesting the possibility of a one-way migration pattern by females. The findings of the present study suggest regional genetic structuring of P. homarus across the Indo-West Pacific, and consequently the assignment of different genetic stocks, or management units, for this lobster species. Finally, the strength of microsatellite markers as a useful resource for parentage assignment in simulated P. ornatus breeding programs was examined (Chapter 6). Results indicated that a marker suite of the five loci with the highest PIC could be used to correctly assign parentage with high confidence. Overall, the work in this thesis has significantly advanced our knowledge on recruitment patterns and processes, along with genetic population structure, of two of the most important and heavily exploited tropical spiny lobsters in the Indo-Pacific. Data provided by this thesis will have application in the formulation of new management policies for these species, leading to more sustainable harvest of wild pueruli for fisheries and aquaculture purposes

Species Composition and Diversity of Xanthoid Crabs (Decapoda: Xanthoidea) Among Dead Corals in Nhatrang Bay, South Central Vietnam

A total of 847 xanthoid crabs were obtained from 82 dead coral samples collected in coral reefs of Nhatrang Bay during a biodiversity survey from 22 August to 22 September 2003. Areas sampled included southern and northern Mun Island, Mieu Island, Bai Bang Island, Cau Island and Tam Islan. The material consisted of 72 species among 4 families and 32 genera. Xanthidae was the most diverse and abundant family, representing 71% of all species and 92.1% of all specimens, with Chlorodiella the most dominant taxon. While the two most dominant species, Chlorodiella corallicola and C laevissima, made up only 3% of all species, they represented 54% of the total number of individuals. The Shannon index of species diversity for xanthoid crabs ranged from 2.29 to 4.21. Other indices confirm that Cau Island is the most favorable and the northern site of Mun Island the least favorable in terms of overall xanthoid diversity. The similarity of species composition among all coral reefs was about 40%. The xanthoid community structure of reef-flats among different reefs was more similar than when comparing each reef-flat with the reefslope of the same coral reefs

Periclimenaeus Nufu, A New Species Of Shrimp (Crustacea: Decapoda: Pontoniinae) From Vietnam

Ďuriš, Zdeněk, Horká, Ivona, Hoc, Dao Tan (2009): Periclimenaeus Nufu, A New Species Of Shrimp (Crustacea: Decapoda: Pontoniinae) From Vietnam. Raffles Bulletin of Zoology 57 (2): 453-464, DOI: 10.5281/zenodo.534221

Characterization of polymorphic microsatellite loci for the spiny lobster Panulirus spp. and their utility to be applied to other Panulirus lobsters

The ornate spiny lobster Panulirus ornatus is a commercially important fishery and aquaculture species throughout south-east Asia and Australia. Thirty microsatellite markers were developed for P. ornatus of which 15 loci were consistently amplified and exhibited adequate levels of polymorphism for parentage and population genetic applications. Number of alleles observed per locus ranged from 2 to 23 (mean NA = 9.1 ± 1.4). Observed and expected heterozygosities ranged from 0.03–0.98 (HO mean = 0.61 ± 0.06) to 0.03–0.94 (HE mean = 0.66 ± 0.06), respectively. Microsatellite markers were also tested in three related Panulirus species, P. homarus, P. versicolor, and P. argus, with varying levels of amplification success and polymorphism exhibited

Exploitation of puerulus settlement for the development of tropical rock lobster aquaculture in the Indo-West Pacific

Development of tropical spiny lobster aquaculture has occurred in Vietnam and more recently in Indonesia based on the collection of naturally settling puerulus. Strong market demand for spiny lobsters and static fishery production has driven such development. High availability of lobster seed has been identified for exploitation particularly in some locations and fishing methods have been developed which make capture of these post-larval lobsters quite straightforward. Such pueruli availability may exist throughout the South East Asian region providing opportunity of industry expansion. A research project is supporting assessment of pueruli resources in Indonesia and providing baseline data on puerulus catch. Capture data over several years is now available which provide a comprehensive picture of spatial distribution, species composition, seasonability, inter-annual variability, catch per unit effort, pricing and total production. Methods of puerulus capture, their innovation and evolution are described. The delicate nature of pueruli has resulted in high mortality through the production chain and the processes involved in their handling and improvements recommended are discussed. In particular, a nursery phase close to the point of capture is advisable to produce robust juveniles suitable for transport to grow out locations. Management of the puerulus resources of Vietnam and Indonesia is advisable, but difficult given lack of information about the source breeding populations and effectiveness of the catching methods. Sustainability of the wild catch is of concern but may be offset by development of a hatchery supply. The lobster aquaculture industry of Vietnam has provided demonstrable benefit to coastal fishing communities and is likely to provide equivalent bene fit in Indonesia. Such benefits may be expanded to other parts of South East Asia and hopefully can be achieved on a sustainable basis

Genetic Diversity and Population Structure of the Giant Mottled Eel, <i>Anguilla marmorata</i> Quoy & Gaimard, 1824 in Central Vietnam

The giant mottled eel, Anguilla marmorata, is at high risk of extinction due to overfishing of glass eels and elvers to provide stock for eel farming. In Vietnam, information on the genetic diversity and population structure of this species, which is necessary for resource management, is limited. In order to address this paucity of information, sequencing of the entire mitochondrial control region (mtDNA) was carried out for 176 individuals collected from central Vietnam. The sequences were investigated using various genetic, phylogenetic and population analyses. A total of 165 distinct haplotypes were identified. The percentage of variation within and among populations was 99.26% and 0.74%, respectively. The fixation index was low (0.007) and not significant (p = 0.096). Therefore, panmixia and a lack of significant population genetic structuring seem likely for A. marmorata in central Vietnam. Most sampled eels were genetically similar to eels found in North Pacific populations (Japan, Taiwan and the Philippines), except for one sample from Quang Tri and two samples from Binh Dinh, which had high values of genetic identity (97% to 99%) with South Pacific populations (Tahiti, Fiji, New Caledonia and Papua New Guinea). Taken together, we suggest that A. marmorata from the North and South Pacific populations co-exist in central Vietnam

Data from: Oceanographic currents and local ecological knowledge indicate, and genetics does not refute, a contemporary pattern of larval dispersal for the ornate spiny lobster, Panulirus ornatus in the South-East Asian archipelago

Here we utilize a combination of genetic data, oceanographic data, and local ecological knowledge to assess connectivity patterns of the ornate spiny lobster Panulirus ornatus (Fabricius, 1798) in the South-East Asian archipelago from Vietnam to Australia. Partial mitochondrial DNA control region and 10 polymorphic microsatellites did not detect genetic structure of 216 wild P. ornatus samples from Australia, Indonesia and Vietnam. Analyses show no evidence for genetic differentiation among populations (mtDNA control region sequences ΦST = -0.008; microsatellite loci FST = 0.003). A lack of evidence for regional or localized mtDNA haplotype clusters, or geographic clusters of microsatellite genotypes, reveals a pattern of high gene flow in P. ornatus throughout the South-East Asian Archipelago. This lack of genetic structure may be due to the oceanography-driven connectivity of the pelagic lobster larvae between spawning grounds in Papua New Guinea, the Philippines and, possibly, Indonesia. The connectivity cycle necessitates three generations. The lack of genetic structure of P. ornatus population in the South-East Asian archipelago has important implications for the sustainable management of this lobster in that the species within the region needs to be managed as one genetic stock

Oceanographic currents and local ecological knowledge indicate, and genetics does not refute, a contemporary pattern of larval dispersal for the ornate spiny lobster, Panulirus ornatus in the south-east Asian archipelago

Here we utilize a combination of genetic data, oceanographic data, and local ecological knowledge to assess connectivity patterns of the ornate spiny lobster Panulirus ornatus (Fabricius, 1798) in the South-East Asian archipelago from Vietnam to Australia. Partial mitochondrial DNA control region and 10 polymorphic microsatellites did not detect genetic structure of 216 wild P. ornatus samples from Australia, Indonesia and Vietnam. Analyses show no evidence for genetic differentiation among populations (mtDNA control region sequences ΦST = -0.008; microsatellite loci FST = 0.003). A lack of evidence for regional or localized mtDNA haplotype clusters, or geographic clusters of microsatellite genotypes, reveals a pattern of high gene flow in P. ornatus throughout the South-East Asian Archipelago. This lack of genetic structure may be due to the oceanography-driven connectivity of the pelagic lobster larvae between spawning grounds in Papua New Guinea, the Philippines and, possibly, Indonesia. The connectivity cycle necessitates three generations. The lack of genetic structure of P. ornatus population in the South-East Asian archipelago has important implications for the sustainable management of this lobster in that the species within the region needs to be managed as one genetic stock

GenotypingMicrosatellite_OR_CorrectedNullAllele

Genotyping Data and Diversity Indices of ten microsatellites after correcting null allele