COMPOSITION AND DIVERSITY OF FREE LIVING MARINE NEMATODE ASSEMBLAGES IN THE WEST SEA, VIETNAM N»n Xuan Ouang ''^''',Ann Vanreusel^ Nic Smol^, Nguyen Ngoc Chau*, Nguyen Vu Thanh^ ;.. 18
Trang 1COMPOSITION AND DIVERSITY OF FREE LIVING MARINE NEMATODE ASSEMBLAGES IN THE WEST SEA, VIETNAM
N)»n Xuan Ouang ''^''',Ann Vanreusel^ Nic Smol^, Nguyen Ngoc Chau*, Nguyen Vu Thanh^
; Department of Environmental Management and Technology, Institute of Tropical Biology 85 Tran Quoc Toan, District 3, Ho Chi Minh city,
Vietnam (*) Corresponding author
E-mail: nxquang@scientist.com
2 Marine Biology Section, Biology Department, Ghent University, Krijgslaan 281
S8 B-9000 Ghent, Belgium
3 Postgraduate Inlemational Nematology Course, Vakgroep Biologie,
Ledeganckstraat 35, B-9000 Gent, Belgium
4 Department of Nematology, Inslitute of Ecology and Biological Resources,
Vietnamese Academy of science and Technology
18 Hoang Quoc Viet, Cau Giay, Hanoi, Vietnam
Abstract:
The structure of.free living marine nematode assemblages in the West Sea, Vietnam was firstly carried out in October 2007 The objectives of this research are originally lo find out the composition, densities and biodiversity of the nematode communities in The West Sea
The primitive results of research from 7 sampling stations showed that 93 genera of 22 families, 7 orders of phylum Nematoda were recorded lo present in this area In nematode communities of West Sea, order Monhysterida present as highest dominant in the number of genera (27 genera or 29% of total) Chromadorida are also high with 15 genera (or 16.1% of total), Triplonchida is lowest number of genus in the communities Genera Daplonema develop dominantly in two stations T2 and T5 In the other stations, this position was replaced by Thalassomonhystera in Tl, Terschellingia in T3, Vasostoma in T4, Gomphionema in T6 and Neochromadora in T7 Genera richness ranges from 11-44 genera and densities range 40 -180 inds/100 gram sediment In each sampling stations, number of genera and densities are not equal, they went high in some stations as T2, T3 and T6, T7 but fell lowest in station T4 The nematode assemblages seems increase densities from the East to the West The biodiversity indices as Margalef (d), Shcmon - Weiner (H) were calculated
lo show a scenario with high diversity in which d index ranging from 2.84 -4.81 and H'ranging from 2.71 - 8.26
I Introduction
Researches on nematode assemblages in the sea along the coast like Kenji Kito
(1982), Magda (1985, 1990), Magda et al (1990), and many publications of free
living marine nematode in Vietnam as Doan Canh and Nguyen (2000); Lai et al
Trang 2(2005); Nguyen & Nguyen (2004); Nguyen & Gagarin (2004a); Gagarin & Nguyen (2004b), Gagarin and Nguyen (2005), But there is no publication mentioning about nematode assemblages in the West Sea of Vietaam
The West Sea is the sea area in the South-West Vietnam, partly belonging to Gulf of Thailand, along the coast of 2 provinces Ca Mau and Kien Giang, Vietnam Recently, the catching, aquaculture, economic activities in coastal provinces as Ca Mau, Kien Giang have a number of the impacted to benthic marine environment This paper just aims to present an original general scenario of the Nematode community in sampling field from offshore of Ca Mau coast to near Phu Quoc Island
2 Material and Methods
Sampling field trip:
Nematode samples were collected in the October 2007 in the West Sea along the coast of 2 provinces Ca Mau and Kien Giang toward from the East to the West (The coordinates and sampling map in the Fig 1)
^
.«.«Sai.i
Tl
T2
T3
T4
T5
T6
T7
Coordinates ^ ^
X
104.376082
104.669925
104.765749
104.775999
104.494044
104.501178
104.455861
y
8.727778 8.834485 9.00032 9.336494 9.503449 9.99921 10.210765
Tab 1: The coordinates
Samples collected from boat using a Ponar grab, which weighs 13.7 kg and cover a surface area of 230mm by 250mm The grab is 150mm high In each station one grab was collected subsample for nematode analysis The samples were taken at each station about 100 gram of sediment was collected, no replication took place since it was focused on the qualitatively characterization of the community composition All samples were fixed in hot formalin 4% at 60°C
Samples were sieved through a 38 pm mesh and extracted by flotation with Ludox-TM50 (specific gravity of 1.18) Each time, 200 nematodes were used for making slides and identification All nematodes were identified to genus level using a high magnification microscope Olympus BX41, BX5I and with the helps
of the taxonomy literatures for identification nematode of Wieser (1956, 1959);
Trang 3Plan and Warwick (1983); Piatt and Warwick (1988); Warwick, Piatt and Somerfield, (1998) and Lorenzen (1994)
Data analyses
Data were analyzed using univariate and multivariate techniques The abundance, composition, Margalef diversity, Shannon-Wiener diversity (logj) Hill's (1973) diversity numbers of the order 0, I, 2 and <o-i- were calculated
following the recommendation by Help et al (1988) N° is the number of taxa
present, N| =e" where H is Shannon-Wiener index, Nz is the reciprocal of Simpson's dominance index, and Noo-i- is the reciprocal of the relative abundance
of the most dominant species
Ranked lower triangular similarity matrices were constructed using the Bray-Curtis similarity measure on square root transformed data Ordination was done by non-metric multidimensional scaling (MDS) Datamining and processing were done by applying statistical software PRIMER v6
3 Results and discussion:
The ecological aspects of nematode communities in the West Sea, Vietnam
77/^ composition of nematode communities
The result shows that 92 genera were recorded in this area belonging to 21 families of 6 orders: Enoplia, Chromadorida, Desmodorida, Monhysterida, Areaolaimida, Plectida, and Triplonchida
Tab 2: Taxonomic overview of the nematode genera in the West Sea
Phylum NEMATODA Polls, 1932
Class ENOPLEA Inglis, 1983
Subclass ENOPLIA Pcarse, 1942
I Order ENOPLIDA Filipjev, 1929
Suborder Ironina Siddiqi 1983
Superfamily Ironoidea de Man, 1876
Family Ironidae de Man, 1876
1 Trissonchulus Cobb, 1920
2 Dolicholaimus de Man, 1888
3 Thalassironus de Man, 1890
Family Oxystominidae Chitwood, 1935
4 Halataimus de Man, 1888
5 Oxyslomina Filipjev, 1921
6 Wieserla Gcrlch, 1956
Suborder Oncholaimina De Coninck, 1965
Superfamily Oncholaimoidea Filipjev, 1916
Family Oncholaimidac Filipjev, 1916
7.1-'/scoj/a de Man, 1890
8 Oncholaimm Dujardin, 1845
9 Oncholaimellus de Man, 1890
10 Prooncholaimus Micoletzky, 1924
Class CHROMADOREA Inelis 1983
Trang 4Subclass C H R O M A D O R I A Pearse, 1942
li Order CHROMADORIDA Chitwood, 1933
Suborder Chromadorina Filipjev 1928
Superfamily Chromadoroidea Filipjev, 1917
Family Chromadoridae Filipjev, 1917
11 Neochromadora Micoletzky 1924
12 Ptycholaimellus Cobb, 1920
13 Spilophorella Filipjev, 1917
14 Chromadorella Filipjev, 1918
15 innocuonema IngMs, 1969
\ 6 Acanlholaimus AWgen, 1933
17 Acllnonema Cobb, 1920
18 Chromadora Micoletzky, 1924
Family Etlimolaimidae Filipjev \k Schuurmans Slekhoven, 1941
19 Gomphionema Wieser va Hopper, 1966
20 Gomphionchus Piatt 1982
Family Cyatholaimidae Filipjev, 1918
21 Maiylynia Hopper, 1977
22 Paralongicyatholaimus M\co\cizky, 1924
23 Minolaimiis Vitiello, 1970
24 Poracyatholaimus Micoletzky, 1924
25 Acanihonclms Cobb, 1920
26 Paracanihochus Micoletzky 1924
Family Selachinematidae Cobb 1915
ll.SvnonchiellaCobh 1933
III Order DtSMODORlUA De Conmck, 1965
Suborder Desmodorina De Coninck 1965
Superfamily Dcsmodoroidca Filipjev, 1922
Family Desmodoridae Filipjev 1922
28 Desmodora de Man 1889
29 Metachromadora Filipjev, 1918
30 Molgolaimus Ditlevsen, 1921
31.0m'.rCobb 1891
32 5/7//-m/t7 Gerlch 1963
33 Siginophoranenia Hope and Murpliy 1972
34 Zalonema Cobb, 1920
35.Cflto/j^o/flCobb, 1920
36 Polysigma Cohb 1920
Superfamily Microlaimoidea Micoletzky, 1922
Family Microiaimidae Micoletzky, 1922
37 Calomicrolaimus Lorenzen, 1971
3Z Bolbolaims Cohb, 1920
Family Moiiopsthiidae Filipjev
39 Rhinema Cobh, 1920
IV Order MONHYSTERIDA Filipjev, 1929
Suborder Monhysterina De Coninck and Schuurmans Stekhoven, 1933
Superfamily Monhysteroidea de Man, 1876
Family Monhysteridae de Man, 1876
40 Thalassomonhysterera Jacobs, 1987
41 Diplolaimelloides Meyl, 1954
Superfamily Sphaerolaimoidca Filipjev 1918
Family Sphaerolaimidae Filipjev 1918
42 Parasphaerolaimus Gourbauil and Boucher, 1981
Trang 543 Sphaerolaimus Bastian 1978
44 Subsphaerolaimus Lorenzen 1978
Family Xyalidae Chitwood, 1951
45 Daplonema Cobb, 1920
46 Theristus Bastian, 1865
47 Co66/adeMan, 1907
48 Linhystera Juario, 1974
49 Metadesmolaimus Stekhoven 1935
50 Paramonhystera Wieser, 1956
5i Pseudosiineria V^ieser, 1956
52.5'/e//7er/(7 Micoletzky, 1922
53 Ammoihehsius Lorenzen 1977
54 .imphimonhystrella Timm, 1961
55 £/ra/w Gerlach, 1957
56 Promonhystera Wieser, 1956
51 Stylotheristus Lorenzen, 1977
58 rfl/vffe/fl/'maj Lorenzen, 1977
Suborder Linhomoeina Andrassy, 1974
Superfamily Siphonolaimoidea Filipjev 1918
Family Siphonolaimidae Filipjev 1918
59 Siphonolaimus de Man, 1918
Family Linhomoeidae Filipjev, 1922
60 Desmolaimus de Man, 1880
61 Terschellingia de Man, 1888
62 Anticyalhus Cobh, 1920
63 Eumorpholaimus Schulz, 1932
64 Megadesmolaimus Wieser, 1954
65 Paralinhomoeus de Man, 1907
V Order ARAEOLAIMIDA De Coninck and Schuurmans Stekhoven, 1933
Superfamily Axonolaimojdea Filipjev, 1918
Family Axonolaimidae Filipjev, 1918
66 Parodontophora Timm, 1963
67 Pseudolella Cobb, 1920
68 Axonolaimus de Man 1889
69 ,-fjco/o/w«j Ditlevsen 1918
IQ.Synodontiimt Cobh, 1920
Family Comesomatidae Filipjev, 1918
71 Actarjonia Hopper, 1967
72 Cervonema Wieser, 1954
73 Dorylaimopsis Ditlevsen, 1918
74 //o/j/jer/fl Vitiello 1969
75 Paracomesoma Hope and Murphy, 1972
76 Paramesonchium Hopper, 1967
77 Pierrickia Vitiello 1970
78 Sabalieria Rouviffe, 1905
79 (asosioa Wieser, 1954
80 Comesomoides Gourbauil, 1980
81 Seiosabatieria Plall 1985
82 Comesoma Bastian 1865
Family Diplopeltidae Gerlach, 1950
83 Araeotaimus de Man, 1888
84 Cainpylaimus Cohh 1920
85 Diplopeliula Gerlach, 1950
396
Trang 6B6 Southerniella AWgen, 1932
VI Order PLECTIDA Malakhov, 1982
Superfamily Haliplectoidea Chitwood, 1951
Family Haliplectidae Chitwood, 1951
87 Haltplectus Cobb, 1913
Superfamily Leptolaimoidea Orley 1880
Family Aegialoalaimidae Lorenzen, 1981
88 Aegialoalaimus de Man, 1907
89 Cyarionema Cobb, 1920
90 Southernia A\\%en, 1929
Superfamily Ceramonematoidea Cobb 1933
Family Ceramonematidae Cobb, 1933
91 Metadasynemella De Coninck, 1942
^2 Pselionema Cobb, 1933
Comesomalidae
Xyalidae
^onoiaimiOae
ChromadonddS
Oxystomindae
Desmodoridae
Ethmalalmldae
Linhomoeidae
Oncholaimodae
Sphaerolaimidae
Honhysleridae
Cyatnolalmldae
Ceramanematida
OlplopeKidae
siphonolaimidae
Aegialoalaimidae
Ironidae
Miaolaimidae
Rh a bdo dem anil d
Halipiedidae
Monoposthlidae
Seiadinematidae
Fig 2: The family composition of
nematode communities in the West Sea
itematode assemblages
T4 T5 TB 17
Stalon Fig, 3: The age structure of nematode
communities
In this area, 2 families Comesomatidae and Xyalidae develop quite high with 33,7% of total nematode assemblage, meanwhile Monoposthlidae and Selachnematidae present only 0,1% oftotal(Fig 2)
Some genera develop quite high densities to dominate in each sampling stations like
Thalassomonhystera, Daptonema, Terschellingia Vasostoma, Daptonema, Gomphionema, Neochromadora from station Tl to
T7
The densities and age structure of
Densities of nematode assemblages in this area were found quite low It ranges from 40
-180 inds/100 grams The value tends to increase from T l - t d T7, decreasing lowest at T4 but having highest value at T7 In the structure
of nematode communities, number
of female individual is much higher than male and juvenile in almost sampling stations!
Th e diversity of n ematode
Trang 7communities
Even densities of nematode assemblage in this area is not so high but the diversity was measured for Margalef diversity index ranging from 2,7 - 8,5 and Shannon -wiener index ranging from 2,8 - 4,8 Those stations in coast of Ca Mau province seem higher diversity than those in coast of Kien Giang province Hill indices also perform a scenario that diversity in the coast of Ca Mau and Kien Giang province are divided at station T4
T2 T3 T4 T5 Te T7
Fig 4: The Margalef index (d) and
Shannon-wiener index (H') Fig 5: The Hill indices of nematode communities
Multt dimension scaling (MDS) of nematode distribution
• « " ;
Analyze on ordination by non-metric multidimensional scaling to perform as figure 6 The graph shows that almost sampling stations in Kien Giang province area are close relationship in ecological aspect of nematode assemblage with similarity more than 40% Meanwhile, in those sampling stations in Ca Mau province, nematode distribute rather desultorily
4 Discussion Due to the aim of this research is just to provide pritiitive data of nematode assemblage in the West Sea, Southern Vietnam This place belongs to tropica climate so the authors would like to compare with the nematode assemblages m Ha Long Bay (semi-tropical climate region) and with North Sea (temperature climate) It is quite difficult to compare the composition, densities and biodiversity of nematode assemblage among the results in the world because of Fig 6: Multi dimension scaling (MDS) of
nematode distribution
Trang 8different authors, methods and the way to perform data However, the comparison
can make clearly the ecological characteristic of nematode assemblage in the study
sea area
The composition and biodiversity in each sampling stations are not eqiiitable
Number of genus and the composition of nematode assemblages alter in almost
stations Genera richness is quite high with 93 genera in this sea area to compare
with some other area in Vietnam like Ha Long Bay about 68 genera (Nguyen,
2004), lower than in the North Sea about 159 genera (Vincx, 1990) In the
nematode assemblages, only genus Daptonema appears dominantly in both stations
T2 and T5 The other dominant genera are Thalassomonhystera, Terschellingia,
Vasostoma, Gomphionema, Neochromadora distribute develop high densities in
Tl, T3, T4, T6 and T7 Similar to nematode assemblage in Ha Long bay of
Nguyen, (2004), Comesomatidae develop most dominantly about 17,2% of total
individual but family Xyalidae are also found as a high densities in this area around
16,5% (this family is only 7% in Ha Long Bay) Those families ComesornftiSae,
Xyalidae, also develop dominantly in the North Sea (Vincx, 1990)
The similarity among sampling stations are only about more than 20%,
especially this three stations T5, T6, T7 are close relationship (similarity of
Bray-Curtis more than 40%) However, this value is much lower than in Ha Long Bay in
the North (about more than 40% percentage of similarity) (Nguyen, 2004)
Diversity is determined at different levels of the nematode communities (Vincx,
1989) Diversity in this place of nematode assemblage rather high variant
(Margalef index=2,7-8,5 and Shanon-Wiener index H'=2,8-4,8) comparing to
nematode communities in the North Sea of Vincx (1990) (about H' = 4 - 4,5 in the
open sea) Meanwhile, diversity of nematode assemblage in Ha Long Bay about
Margalef d = 2,35-6,01 and Shanon-weiner indexH'=l,59-3,07
S Conclusion
The primitive result expresses that nematode assemblage in the West Sea, South
Vietnam is quite diversity and high genera richness 92 genera of 21 families were
recorded to present in this tropical sea area Some dominant genera Daptonema,
Thalassomonhystera, Terschellingia, Vasostoma, Gomphionema, Neochromadora
develop trongly in 7 stations Comesomatidae and Xyalidae appear as a high
distribution in this sea area The diversity of nematode assemblages in this area was
measured quite high with Margalef diversity index ranging from 2,7 8,5 and
Shannon -wiener index ranging from 2,8 - 4,8
Acknowledgment: The authors are grateful to Dr Nguyen Xuan Thuyen, Faculty
of Biology, Ho Chi Minh National University of Natural Science due to supporting
for sampling field trip We also would like to thank to Mr Nguyen Van Sinh, and
Ms Doan Thi Dung in Inslitute of Tropical Biology for technical assissance
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