KHOA HOC CbNG N G H £
AlVIH HUOIVIG CLJA IVIAT DO UOIMG V A CAU TRUC l\IEI\l D A Y DEI\I SIIVH TRUOiVlG V A TY LE SOIXIG CLIA ALJ TRUIMG IXIGHEU [Meretrix iyrata\ T U GIAI DOAIM
D O I T U DO (D - V e l i g e r ) DEIM GIAI DOAIM S A U DIEIM T H A I ( p a s t - m e t a m a r p h a s i s ]
Chu Chi Thidt\ Trdn Thi Kim Anh^
T6MT.\T
Au triing .ighdu Ben T r e (Meretrix lyrata) a giai doan boi tu do (D - Veliger), duoc ucmg den giai doan sau bien thai (post-metamon)hosis), xudt hidn chdn bo, phat bien thanh ngheu gidng spat. Co 2 thi nghidm duoc tien hanh la: 0 thi nghidm uong t'iu trung nghdu giai doan boi tu do a cac mat do 5, 10 va 15 con/ml, va iO thi nghiem uong au triing ngheu giai doan bidn thai d cac nen day: day biin, day cat, day vo nhuydn the va day tra. Cac thi nghidm duoc tien hanh trong bd hinh tru tron the tich 100 lit. Ket qua thi nghiem cho thay, tdc do sinh trudng cua du trung uong d niSt do 15 con/ml thap nhat so vdi uong d mat do 5 va 10 con/ml. Nhung d mAt do uong 5 va 10 con/ml, tdc do sinh t m d n g cOia au trimg sai khae khong co y nghia thdng k e (p>0,05). Ty le song ciia du triing boi tu do ty le nghich vdi mat do uong, d mat do uong 15 con/ml, au trung co ty Id sdng thap hon so vdi mSt do uong 5 con/ml va 10 con/ml. Cau tnic ndn day anh hudng den tdc do sinh trudng va ty Id sdng cCia au triing ngheu bien thai. Tdc do sinh trudng va ty le sdng cda au trung bidn thai sau 14 ngay cao nhat d nen day biin va thap nhat d nen day tra. Day cat cho ty le sdng ciia au trimg bien thai cao hon, co y nghla thong ke so vai day vo nhuydn the, nhung khong co y nghla thdng ke (p>0,05) ve tdc do sinh trudng.
Tir khoa: Meretrix lyrata, giai doan bien thai, au tning sau bien thai, day biin, mat dp uong, nen day
LDATVANBE ^ " ^ ^^^ ^^^^ gidng n g h e u B e n T r e trong trai sdn
^ , , , xuat, lam c a s d k h o a h o c d e hoan thidn quy trinh sdn Nghdu Bdn T r e (Meretrix lyrata) la ddi tuong ... .,' . . . u - + —*r-«^ M T
^ , ^ , , , Tr XT xuat giong o q u y m o e o n g nghiep tai Viet N a m la ddng vat than m d m d u o c nudi c h u luc tai Vidt N a m .» i ^ » * > u - u • - - .*•
• ^ • • • , • , , viec l a m d a n g d u g c n g a n h n o n g n g h i e p v a c a c dia trong nhirng ndm vira qua. Ndm 2009, san phdm , .. M u - - - i, -c - - -^
iig iiiiiuig iioiii H - , , , ' p h u o n g quan t a m . Nghien c u u a n h h u o n g c u a m a t nghdu nudi tai Viet N a m ducrc Hdi d d n g quan ly bidn j , - • - * „ - - . * , * - • u 4. -
S11V.U iiuwi icu T ly.. 1 6 M J ^Q u o n g nuoi va cau true n e n day d e n sinh truong va qudc td (MSC) edp Chung n h d n d a t tidu chi MSC, d u ^j^^^ ^^. .^ ^, ^ .^ ^ ^ ^ ^ ^^^^^ (Meretiix lyrata) tii didu kidn dd xudt khau. Theo Vasep (2009), tmh ddn ^.^. ^^^^ b ^ ^^ ^o (D - veliger) ddn giai doan xudng thdi didm 15/11/2009, xudt khdu nghdu tir Viet Nam ^,y (Metamorphosis) nhdm gdp phdn thuc hien muc sang cdc nudc EU, My, Canada, Trung Qudc dat ^X^AA
H. PHUONG PHAP NGHEN CUU
17.624 tan, tri gid trdn 37,2 ti-idu USD. Nhu vdy, nghe nudi ngheu dang dem lai hidu qua kinh te, gdp phan
xda giam ddi ngheo cho cdng ddng cu ddn vimg cua 1. Phuong phdp thidt kd thi nghidm
sdng ven bien Viet Nam. Tuy nhidn, hau hdt nghdu +) Thi nghiem 1: xdc dinh mat do uong du tiling gidng phuc vu nudi thuong pham d nudc ta hidn nay nghdu phii hc^p d giai doan boi ti; do. Mat do thi vdn chu yeu phu thude vdo ngudn gidng khai thdc bj nghidm lan lugt Id 5 con/ml, 10 con/ml vd 15 til nhidn. Trong khi dd, vide khai thdc gidng tir nhidn con/ml, trong 9 be 100 lit, mdi nghidm thuc lap lai 3 mdt cdch d at, khdng cd kd hgach dang Id trd ngai 1 ^ Y{e tiidng nudc chay trdn lidn tiic, vdi nhidt do ldn ddn tinh ben vimg cua nghe nudi nghdu hidn nay. j ^ o ddng tir 23 27^C; do man duy ti-i 25Voo, sue khi Vi vdy, nghien cuu nham gdp phan hoan thidn quy thudng xuydn trong qud trinh uong. Thuc an cho du .,b trung la hdn hgp 3 Igai tao: Isochrysis galbana, ' Phan vien Nghien cuu Nudi trdng Thuy san Bde Trung Nanochloropsis oeulata va Chaetoceros mullerii vdi bp, Vien Nghien ciru Nudi trong Thiiy san I ty Id 1:1:1, tan suat c h o dn 4 lan/ngdy.
^ Khoa Nong Lam Ngu, Dai hoc Vinh
U O N G NGHIEP V A PHAT TRIEN N O N G
THON KY 2 - THANG 1/2012 71
KHOA HOC C b N G N G H l
Thi nghidm dugc tien hanh tir khi au triing d giai doan chii D-veliger, boi ti; do, den giai doan xuat hien chan bd, chuyen xudng sdng day.
•h) Thi nghiem 2. xac dinh cau true ndn day phd hcip eho au triing ngheu d giai doan xudng day. Au triing nghdu dgiai doan bien thai, xuat hien chan bd, bdt dau ehuyen sang giai domi sdng day, ducrc ucmg trong be 100 lit. Thi nghidm ducrc tidn hanh vcri 4 loai nen day khae nhau: day bun, day cat, day bdt vd sd va day trcr. Mdi nghic^m thuc thi nghidm duc.rc bd tri lair lai 3 lan. Au triing ducre ucmg iV mat do 500 eon/em' Ti-ong qua trinh ucmg, nhic't dd nircVc din.rc duy tri trong khoang 25 - 29"C; do man 24"/,K,. sue khi lien tue. Thue dn cho au trung la hdn hc.rir 3 loai tao;
L'^oc^hiysis galixina, Nanochloropsis oeulata va Chaetoceros niulAri voi ty le 1:1:1, ducrc eho .In 4 lan/ngay, mat dd tao ducrc duy tri 200.0(X) te bao/ml nucri.\
2. Phuang phdp thu vd xu ly sd hdu
Xac dinh tang trucmg va ty Id sdng ciia au trung ndi 2 ngay/lan, vcri sd mau do kich thucre ngau nhidn 30 au triing/bd, xdc dinh ty Id sdng bdng phuong phdp dinh lugng. Au triing day duoc do kich thude 3 ngay/lan va xdc djnh ty Id sdng 7 ngay/lan bdng vide thu 1 ml hodc 1 cm^ mau tir mdi be thi nghidm. Cac ydu td mdi trudng be nudi ducrc theo ddi 2 lan/ngdy nhdm didu chinh cho au trung sdng trong dieu kidn tdt nhdt. Sd lieu thi nghidm dug-c phdn tich theo phuong phdp ANOVA, bdng phan mem Graph-Pad Prism 4.
IH. KET QUA NGHEN CUU VA THAO LUAN
1. Mat do uong au triing nghdu phii hgp d giai doan boi tu do
Tdc do sinh trudng
Bang 1. Kich thude trung binh dim) cua du triing nghdu d cdc mat do uong khdc nhau
tdc do sinh trudng binh qudn dao ddng tir 11,60 den 12,37 pm/ngay. 6 mat do 15 con/ml, au triing co kich thuc'rc nhd nhdt, cd y nghia thdng kd (p<0,05), xudt hien tir ngay uong thir 2 so vdi cac mat dd 5 va
10 con/ml vd sir khdc bi^t nay duy ti-i tir ngdy thu 2 ddn ngay thu 8 (^u triing bdt dau xuat hien chan bo, chuydn sang giai doan sdng d day) (bang 1).
Ty le .sdng ciia i'u tning ndi
Bang 2. Ty Id sdng (%) cua du triing nghdu dcdc mdt dp khdc nhau
Ngay nuc'ii Ng.iy 0 N'K.-iy 2 Ngay 4 Ngay 6 Ng;iy 8
Ty le sdng eua au triing (%) 5 eon/ml
100 86,00 ± 2,72"
74,71 1 3,91"
68,251 4,32"
62,18t4,50"
10 eon/ml 100 85,75 i 4.71"
71,36 ±5,10"
65,03i 5,21"
60,1.5± 6,32"
15 con/ml 100 82,85 ±3,12^
65,43 ± 5,2r 61,34±4,9r 55.27i: 5.41'
Ngay nuoi NgayO Ngay 2 Ngay 4 Ngay 6 Ngay 8 ADO (nm/ngay)
Kich thucre cda au triing (jim) 5 con/ml
75,4± 3,8 113,7 ±2,3"
142,9 ±.2,4"
162,3± 2,6"
174,4 ±3,1"
12,37
10 con/ml 75,4± 3,8 111,9 ±2,2"
141,6 ±2,7"
160,4± 2,7"
173,7 ±1,9"
12,28
15 con/ml 75,4± 3.8 103,7 ± 2,9"
138,8 ± 2,2' 156,7± 2,8' 168,2 ± 2,6"
11,60
Ket qua bang 1 cho thay, du triing nghdu M.
lyrata b giai doan chii D-veliger sinh trudng nhanh.
Phan km au triing uong d cdc mat dd ddu bdt ddu bidn tiiai d ngay thir 8. Ty Id sdng dao ddng tir 55,27 den 62,18% (bang 2). Trong dd, ty Id sdng cua aiu triing dat cao nhat d mat dd uong 5 con/ml (62,18%) vd thap nhdt la d 15 con/ml (55,27%). Sir khdc nhau giira ty Id sdng cua au triing ucmg d mat do 5 con/ml va 10 con/ml la khdng cd y nghia (p>0,05), tuy nhidn, sai khdc cd y nghia khi so sdnh vdi mat do 15 con/ml (p<0.05).
Mat dd cd anh hucmg ddn tdng trudng vd ty Id sdng cua au trung ddng vat than mem. Au triing ndi cua chung sir dung vanh Uem mao de van ddng va lge thirc dn, d mat do cao au trung phai canh tranh ve khdng gian sdng vd thuc dn ndn eo tlie gdy ndn sir eg xdt. Sir eg xdt cd tlie lam cho vdnh tidm mao co lai va dan ddn vide ddng kin vd, lam can trd boat ddng bdt mdi va tdng tieu thu ndng lugng (Loosanoff vd Davis, 1963; Sprung, 1984; MacDonald, 1988; Avila va ctv, 1997). Do vay, lira chgn mat do uong rat quan trgng trong trai san xudt gidng. Mdt mat do uong tdi uu ma tai dd hidu qua san xuat cao nhat ma khdng anh hudng ddn tdng trudng va ty le sdng ciia du triing ludn la van de cdn thidt ducrc xdc dinh. Tir kdt qua nghidn ciru nay de nghi mat do 10 con/ml la phii hgp dd uong au triing giai doan trdi ndi, dieu nay cung phii hgp vdi Liu va ctv (2006), Yan vd ctv (2006) khi nghidn ciru trdn ngao Ruditapes philippinarum va Meretrix meretrix.
2. Cdu tnic ndn ddy phii hgp cho au trimg nghdu a giai doan xudng ddy
72 NONG NGHIEP VA PHAT TRIEN NONG THON - KY 2 - THANG 1/2012
JKHOA HOC C 6 N G NGHE
Tdc do tang tnrimg
Bang 3. Kich thude trung binh (pm) ciia du trimg d cdc ndn ddy khdc nhau
Ngay nuoi Ngay-1
(9) Ngay-3
(12) Ngay-6
(15) Ngay-9
(18) Ngay- 12 (21)
Ngay- 15 (24)
Cau tnic nen day Bun
173,3±5,1 204,5±2,6' 371,8:^2,a•' 510,0±.>,7»
680,2±2,5' 763,9±2,3"
Cat 173,4±5,3 204,0±3,1"
371,9±1,9' 507,6±4,P 511,4±3,3"
678,7±3,5"
Vo nhuydn th^
173,6±5,1 204,4±3,3"
371,4±1,4"
467,6±4,0"
511,8±2,5"
680,atl,9"
Tra 173,4±5,2 204.5±2,6"
301,5±5,8"
421,3±3,4'- 474,1±4,5^
535,9±3,e"
Kdt qua d bang 3 cho thay sau 3 ngdy uong cho thay, kich thuck: du triing khd ddng deu d cac ndn ddy khdc nhau. Su khdc nhau ve kich thude cua au triing xudt hidn tir ngay thu 6, d be cd nen day tro, kich thude au triing la 301,5±5,8 pm, thap nhdt, cd y nghla thdng kd (p<0,01) so vdi du triing d cdc nen ddy cdn lai. Su khdc nhau khdng cd y nghia thdng kd (p>0,05) ve tdc do smh trudng ciia du triing trong cdc be thi nghidm cd ndn day Id biin, cdt vd vd nhuydn the d ngdy thu 6. Den ngdy thu 9, su khdc bidt ve tdc do sinh trudng d cdc nen ddy khd rd rdng hon, cu the la au trung d nen ddy tra cd kich thucre nhd nhat
(421,3±3,4 pm), tidp den la day vd nhuydn the (467,6±4,0 pm), khdc nhau cd y nghla thdng kd.
Khdng cd su khdc bidt giira 2 nen day bun vd cdt ddi vdi tdc do sinh trudng cua du triing d ngdy thu 9.
Didn bidn vd sinh trudng cua du triing nghdu d nhirng ngdy cudi ciia thi nghidm (ngdy thii 12 vd 15) tirong ddi gidng nhau, cu the, kich thude ciia du tiling d nen ddy biin la ldn nhat (763,a±2,3 pm), khdc nhau cd y nghla thdng kd (p<0,05), tidp theo Id d nen ddy cdt (678,7±3,5 pm), vd nhuydn tiie (680,0^1,9 pm) vd cudi ciing Id day tro (535,a±3,6 pm). Giira nen ddy cat va ddy vd nhuydn thd, tdc do sinh trudng ciia du triing nghdu d thdi diem kdt thiic thi nghidm Id khdc nhau khdng cd y nghia tiidng kd (p>0,05). Nhu vdy, cd the su dung bdt vd nhuydn the trong vide lam vdt lieu dd thu du triing nghdu xudng ddy.
Tyle sdng
Kdt qua d bang 4 cho thay, sau 7 ngdy uong nudi, ty Id sdng cua hdu au triing xudng ddy khdc nhau cd
y nghla thdng ke (p<0,05) d cac nen day khdc nhau.
Didn bidn ty Id sdng ducre duy tri den ngay ket thile thi nghidm. Ket qua thi nghiem chi ra rdng, day bun phu hcrp nhat (10,44±0,02%) ddi vcri au trung nghdu d giai doan bien thai, chuyen tir ddi sdng boi tu do sang sdng viii d day, tiep dd'n la day cat (6,11±0,19%), day vd nhuydn the (5,44±0,19%) va clay tro (2,89±0,19%).
Nhu vay, nen day biin phii hgp vdi au triing ngheu d giai doan bidn thai, chuyen tir ddi sdng bcri ldi tu do xudng day. Tuy nhien, vcri ty Id sdng 5,44±0,19%, bdt vd nhuyen the cd the xem xet de lam gid the cho du triing ngheu d giai doan xudng day.
Bang 4. Ty Id sdng ciia au triing nghdu d cdc ndn ddy khdc nhau
Ngay nuoi Ngay- 7 Ngay-
14
Cau tnic nen clay Bun
44,56±0,5P 10,44±0,02'
Cat 28,78±0,19"
6,11±0,19"
Vo nhuyen the 25,22±0,5r
5,44±0,19'"
Day tra 14,00±0,33'' 2,89*0,19^
Au triing nghdu phat trien binh thudng; vd cau tnic nen day anh hudng dang ke den bien thai cua du trung ngheu. Tuy nhidn, hinh dang vd kich thude hat cdt ldm gia the khdng dnh hudng den ty Id bidn thdi cda chung.
IV. KET LUAN
Mat do au triing nghdu M. lyrata phu hgp cho uong nudi trong trai san xuat gidng, nhu dieu kidn thi nghidm, phu hgp nhat la 10 con/ml.
Nen day phu hgp cho au trung giai doan bidn thdi, chuyen tu ddi sdng boi tu do xudng sdng ddy Id ddy biin (ty Id sdng 10,44±0,02%). Tuy nhidn, ndn ddy cat cho ty Id sdng 6,11±0,19% vd day vd nhuydn tiie cd ty Id sdng 5,44±0,19% cd the dugc xem xdt de lam gid the thu du triing nghdu xudng ddy b-ong trai san xudt.
TAI UEU THAM KHAO
1. Avila, C, Grenier, S., Tamse, C. T., Kuzirian, A.
M., 1997. Biological factors affecting larval growth in the nudibranch mollusc Hermissenda crassicornis (Eschscholtz, 1831). J. Exp. Mar. Biol. Ecol. 218, 243-262.
2. Helm, M. M. and Bourne, N., 2004. Hatchery culture of bivalves, a practical manual. FAO fisheries technical paper 471.
NONG NGHIEP VA PHAT TRIEN NONG THON KY 2 - THANG 1/2012 73
KHOA HOC CbNG N G H l
3. Holliday, J. E., Maguire, G. B., Nc>ll, J. A., 1991.
Oplinium stocking density for nui-seiy eultnre of Sydney rock oysters (Saeeostrea eomniercialis).
Aquaculture 96, 7-16.
4. Ixrosanoff, V. L, Davis, II. C , 1963. Rearing of bivalve molluscs. In: Russell, F.S. (Ed.), Advances in Marine Biolcrgy, vol. 1. AeadcMiiie Prc-ss, b)ndon, p]r.
1-136.
5. Liu B., Dong, B., Tang, V>., Zliang, T., Xiang, J., 2006. Effect of stocking density on grcrwth, settlement and survival erf clam larvae, MereULx /7;e/-e/!7-ZvLinnaeus. Aciuacullurc 258: 344-349.
(). MacDonald, B. A., 1988. Physiological energetics of Japanese scallop Patinopecten yessocnsis larvae. J. Exp. Mar. Biol, E(:ol. 120, 155- 170.
7. Sprung, M., 1984. Physiological energetics of mussel larvae (Mytilus edulis). I. Shell growth and biomass. Mar. Ecol., Prog. Ser. 17, 283-293.
8. Yan, X. W., Zhang, G. F., Yang, F., Yan, X., Zhang, G., 2006. Effect of diet, stocking density and environmental factors on growth, survival, and metamorirhosis of Manila clam Ruditapes philippinarum h\rvac. Aquaculture 253 (1-4): 350-358.
THE INFLUENCES OF ITIE BFEEDING DENSHY AND THE STRUCTURE OF THE WATER BODYS BED ON THE GROWTH AND SURVIVAL RATE OF MERETRYX (Meretiyx byrata) FROM D- VEUGER
STAGE TO POST LARVAE STAGE
Chu Chi Thiet, Tran Thi Kim Anh Summary
Tlie larvae of clam .Meretrix lyrata at swimming sL'ige (D-veliger) were reared unUl post-metamorphosis larvae stage; called crawl larvae that ready to become spat. Two experiments were conducted such as: i) the experiment on rearing clam larvae at different stocking densities such as 5, 10 and 15 larvae per ml, and ii) the experiment on rearing crawled larvae of clam in different substrata such as clay, sandy, scallop powder and tank bottom (bare substrate). The experiments were conducted in 100 litter cylinders in the hatchery in June 2010. Tlie results of experiments indicated that the growth rate of larvae at density of 15 units per ml was the lowest, significant difference compared to their growth at the density 5 and 10 units per ml, but no significant difference between density of 5 and 10 units per ml. The survival rate of swimming larvae was inversely proporbon to the experimental densities, the lowest rate at 15 con/ml and there was a significant difference (p<0.05) compared to 5 larvae/ml and 10 larvae/ml. The constmction of substrate also affected to growth rate and survival rate of post-metamorphosis larvae. Growth rate and survival rate of post metamorphosis larvae at day-14 reared in clay of substrate was highest, significant difference compared to its in sandy, scallop powder, and bare substrata. The post-metamorphosis larvae were lowest growth rate and survival rate in the bare substrate, significant difference compared to other substratas under this experimental condition.
Key words: Meretrix lyrata, metamorphosis stage, post-mctaniorphosis larvae, clay substrate, stocking density.
Ngudi phan bidn: TS. Nguydn Quang Himg
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