Phân bố vi tảo độc hại tại một số vùng nuôi trồng hải sản tập trung ven biển Việt Nam

Tieu ban: CONG NGHE SINH HQC B | £ N V A MOI TRLfONG 491<br /> <br /> <br /> <br /> <br /> PHAN BO VI TAO DOC HAI TAI MOT SO VUNG NUOI TRONG<br /> HAI SAN TAP TRUNG VEN BIEN VIET NAM<br /> • •<br /> <br /> Chu Van Thuoc', Nguyen Thj Minh HuyenS Le Thanh Tii^g^<br /> Ton That P h a p ^ Nguyen Nggc L a m \ Do Thj Bich Loc*<br /> l-Vi?n Tdi nguyen vd Moi truomg bien, Vien Khoa hpc va Cong nghe Viet Nam<br /> 2- Vien Nghien ciru Hdi san, Bp Nong nghiep va Phat trien nong thon;<br /> 3-Tnrdng Dai hpc Khoa hpc, Dai hpc Hue;<br /> 4- Vien Hdi duang hpc, Vien Khoa hpc va Cong ngh4 Vi^t Nam;<br /> 5- Vien Sinh hpc Nhiet ddi, Vien Khoa hpc va Cong nghe Vi^t Nam<br /> <br /> <br /> I. M d DAU<br /> Vi tao frong cae hf sinh thai thiiy vyc, ngoai chiire nang la nhirng sinh vat san xuit tao ra<br /> nang suat so cap, chiing con la ngudn dinh dudng chii yeu eua nhieu loai dgng vat phu du, au<br /> trimg giap xac, mgt s6 dgng vat than mem an lgc, ca... Phan Idn cac loai vi tao la co lgi cho cac<br /> sinh vat khac. Tuy nhien, frong tdng s6 5000 loai tao phii du da dugc phat hien fren the gidi cd<br /> khoang 300 loai thugc tao silic (Bacillariophyceae), tao giap (Dinophyceae), tao lam hay vi<br /> khuan lam (Cyanophyceae) va mgt s6 vi tao co roi khac co the gay thuy trieu do (red tide), frong<br /> do khoang 60-80 loai co kha nang gay hai, mac dii chi khoang 40 loai co the san sinh dgc to, gay<br /> hai cho cae sinh vat khac tham chi nguy hiem den sue khoe con ngudi. Vifc dieu fra nghien cuu<br /> tao dgc hai va cac dgc t6 do chimg san sinh ra co tam quan frgng ca ve mat khoa hgc cung nhu<br /> frong thyc tien san xuat nhat la frong nghe nu6i thuy san. Dac bift d6i vdi van de an toan thyc<br /> pham hai san, sy hifn difn ciia tao dgc hai frong m6i trudng nude ciing nhu du lugng dgc t6 tao<br /> frong mo cua cae loai dgng vat than mem hai manh v6 (DVTMHMV) la nhirng chi tieu can phai<br /> kiem soat, quan trac djnh ky.<br /> Tir nhung ly do fren, nham gop phan dieu fra, phat hifn tao dgc hai d vimg ven bien Vift<br /> Nam, cung nhu tim hieu nhirng anh hudng ciia chiing tdi cac loai hai san, tir nam 2004 den 2005,<br /> de tai khoa bgc cap Nha nude "Dieu tra, nghien cuu tdo dpc, tdo gdy hpi a mpt so viing nuoi<br /> trong thuy san tap trung ven bien, de xuat gidi phap phong ngira, giam thieu nhung tdc hgi do<br /> chiing gdy ra " (ma sd KC-09-19) da dugc trien khai. Sau hai nam thyc hifn, budc dau de tai da<br /> dua ra dugc mgt s6 dan lifu nghien cim kha d6ng bg, co hf thong vf vi tao dpc hai d vimg ven<br /> bd Vift Nam noi chung va cac vimg nu6i frong hai san tap trung ven bien noi rieng. Day la<br /> nhung CO sd khoa hgc can thiet giiip cho vifc xay dyng hf th6ng quan frac, giam sat tao dgc hai<br /> d vimg ven bif n nude ta.<br /> Bai viet nay trinh bay cac ket qua nghien cim ve thanh phin loai va phan bd tao dgc hai tai mgt<br /> so vimg nu6i fr6ng hai san tap trung ven bien Vift Nam frong cac nam 2004,2005 cua de tai noi fren.<br /> <br /> n. DOI TtrgfNG vA PHUONG PHAP NGHIEN cutr<br /> 1. Doi tirong, thdi gian va dia diem nghien cihi<br /> D6i tugng nghien curu la cac loai tao dgc hai s6ng phii du va s6ng day thugc cae ldp tao<br /> Bacillariophyceae, Dinophyceae, Cyanophyceae va mgt s6 tao khac hifn difn frong m6i trudng<br />  Tuyln tap H$i nghj KHOA HOC T O A N Q U O C V £ SINH HOC BifeN vA P H A T T R | £ N B^N\fiiKr^<br /> 492<br /> <br /> nu6i fr6ng tiiuy san ven biln Vift Nam. Mgt s6 ylu to m6i frudng tiiuy vyc (nhu cac ylu t6 thuy<br /> ly, thuy hoa, cudng do birc xa v.v..) lien quan den qua tiinh phat sinh, phat tinen mat dp tao dpc<br /> hai cung da dugc do dac, khao sat djnh ky.<br /> Dja dilm nghien cuu bao g6m: Ven biln Bic Bg (3 vimg): D6 Son, Cat Ba (Hai Phong),<br /> Tiln Hai (Thai Binh); ven biln Trung Bg (2 viing): Dim Lang Co (Thira Thien - Hue), Dim Nha<br /> Phu (Khanh Hoa) va ven biln Nam Bg (2 vimg): Binh Dai (Ben Tre) va Can Gid (TP. HCM).<br /> Tai m6i vimg tiln hanh nghien cim, khao sat tai hai loai tiiiiy vyc: cac ao nu6i_t6m frong de va<br /> vung nude ngoai de hifn dang nuoi DVTMHMV. Qua tiinh khao sat, thu mau vat dugc tien<br /> hanh djnh ky hang thang vao cae ky frieu cudng, lien tyc frong 12 tiiang, tir thang 5/2004 den<br /> thang 4/2005. Rieng khu vyc D6 Son - Cat Ba moi tiiang tiiu mau 2 dgt<br /> <br /> 2. Phirong phap nghien ciru<br /> Nghien cuu tao dgc hai chu yeu dya tren co sd phuang phap nghien cuu ve thyc vat phii du<br /> dugc bien soan frong tai lifu "Phytoplankton manuaF [Soumia, 1978], va eac hudng dan nghien<br /> cuu tao dgc hai trong cac tai lifu "Manual on harmful marine microalgae" [Hallegraeff va ct-<br /> 2004] va "Design and implementation of some harmful algal monitoring system" [Andersen,<br /> 1996] do UNESCO in hanh.<br /> <br /> ra. KET QUA NGHIEN ClTU VA THAO LUAN<br /> <br /> \. Thanh phan loai tao dgc hai tai cac viing nuoi hai san tap trung ven bien Vift Nam<br /> Kit qua phan tich cac miu vat thu thap frong thdi gian tii thang 5/2004 din thang 4/2005 t?i<br /> cac vimg nu6i frong thuy san ven biln cac tinh Hai Phong, Thai Binh, Thira Thien Hue, Khanh<br /> Hoa, Bin Tre va TP. Ho Chi Minh cho thiy, budc diu da xac djnh dugc 61 loai va nhom loai tao<br /> dgc hai thugc 25 chi nim frong 4 ldp tao. Trong do da dang nhit thugc ve ldp tao gidp<br /> (Dinophyceae), gap 47 loai, 16 chi (chilm 77% t6ng s6 loai); tilp theo la cac ldp tao silic<br /> (Bacillariophyceae) co 8 loai va nhom loai, 5 chi (13,1%); ldp tao lam (Cyanophyceae) co 4 loai, 3<br /> chi (6,6%) va it nhit la ldp tao kim (Dictyochophyceae) gap 2 loai, 1 chi (3,3%). Trong so 25 chi<br /> tao da dugc phat hifn, chi Alexandrium co sd loai phong phii nhat (14 loai), tilp theo la hai chi<br /> Dinophysis.Prorocentrum, m6i chi gap 7 loai, cac chi con lai gap tir 1 den 3 loai (bang 1).<br /> <br /> Bang 1. Danh mi^c thanh phin loai tao dgc hai d cac vung nghien cii'u<br /> <br /> Dja dilm phan bd<br /> Ten loai / Nhom loai TP.<br /> TT Hai Thai TT- Khanh B§n<br /> Phong Binh Hul Hoa Tre HCM<br /> (1) (2) (3) (4) (5) (6) (7) (8)<br /> <br /> 1- Ldp Tao lam (Vi khu4n lam) -<br /> CYANOPHYCEAE<br /> 1 Trichodesmium erythraeum + + + + . + +<br /> <br /> 2 T. thiebautii + + +<br /> 3 M/croc/sfe spp. + + +<br /> 4 Anabaena circinalis +<br /> II- Ldp Tao Silic - BACILLARIOPHYCEAE<br /> 5 Pseudo-nitzschia sp.1 ( cf. pungens) + + +<br /> Ti^u ban: CONG NGHE SINH HOC BI^N v A MOI TRl/brNG 493<br /> <br /> <br /> (1) (2) (3) (4) (5) (6) (7) (8)<br /> <br /> 6 P. sp.2 ( cf. delicatlssima) + + +<br /> 7 P. pseudodelicatissima (= P. calliantha) +<br /> 8 Pseudo-nitzschia spp. + + +<br /> 9 Amphora coffeaeformis +<br /> 10 Thalassiosira spp. + + + + +<br /> 11 Skeletonema costatum + + + + + +<br /> 12 Chaetoceros spp. + + + + + +<br /> Ill- L d p Tao Giap - DINOPHYCEAE<br /> 13 Alexandrium acatenella + +<br /> 14 A. affine + + + +<br /> 15 A. foedum +<br /> <br /> 16 A. fraterculus + +<br /> <br /> 17 A. globosum +<br /> <br /> 18 A. insuetum + +<br /> <br /> 19 A. leei + + + +<br /> <br /> 20 A. minutum + +<br /> <br /> 21 A. ostenfeldii +<br /> <br /> 22 A. pseudogonyaulax + + + +<br /> <br /> 23 A. cf. tamarense + +<br /> <br /> 24 A. tamiyavanichii + +<br /> <br /> 25 A. tamutum +<br /> <br /> 26 A. sp. + + +<br /> <br /> 27 Dinaphysis cf. acuminata +<br /> <br /> 28 D. caudata + + + + + +<br /> <br /> 29 D. hastata +<br /> <br /> 30 D. miles + + +<br /> <br /> 31 D. mitra + +<br /> <br /> 32 D. cf. rotundata + + +<br /> <br /> 33 D. sp. + + +<br /> <br /> 34 Prorocentrum balticum +<br /> <br /> 35 P micans + + + + + +<br /> <br /> 36 P. cf. rhathymum + + +<br /> <br /> 37 P. emarginatum + +<br /> <br /> 38 P. lima + + +<br /> <br /> 39 P. maculosum +<br /> <br /> 40 P. minimum + + +<br /> "<br /> 494 Tuyen t§p H$i nghj KHOA HQC TOAN Q U 6 C V £ SINH HQC BI^N VA PHAT TRifeN B£N Vff>i>><br /> <br /> <br /> <br /> (1) (2) (3) (4) (5) (6) (7) (8)<br /> <br /> 41 P. sp. +<br /> <br /> 42 Gambierdlscus toxicus +<br /> <br /> 43 G. yasumotoi +<br /> <br /> 44 Ostreopsis ovata + +<br /> <br /> 45 Coolia monotis + +<br /> <br /> 46 Gonyaulax spinifera + + + + + +<br /> <br /> 47 G. poly gramma + + + + + +<br /> <br /> 48 G. verier + + + + +<br /> 49 Lingulodinium polyedricum + +<br /> <br /> 50 Protoceratium reticulatum +<br /> <br /> 51 Protoperidinium crassipes + +<br /> <br /> 52 Peridinium quinquecorne + + + +<br /> <br /> 53 Noctiluca scintillans + + + + + +<br /> <br /> 54 Ceratium furca + + + + + +<br /> 55 C. fusus + + + + +<br /> 56 C. trich oceros + + + +<br /> <br /> 57 Scrippsiella cf. trochoidea + + +<br /> <br /> 58 Polykrikos schwartzii + +<br /> <br /> 59 Amphidinlum klebsii +<br /> <br /> IV- Ldp tao Kim - Dictyochophyceae<br /> <br /> 60 Dictyocha speculum + + + + + +<br /> <br /> 61 D. fibula + + + + + +<br /> <br /> Tong s6 50 29 35 37 14 18<br /> <br /> Ghi chii: + Lodi co mat<br /> Trong danh sach thanh phan loai tao dgc hai dugc lift ke frong bang 1, ngoai nhimg loai da<br /> dugc ghi nhan la co kha nang sinh cac dgc t6, dya vao cac din lifu nghien curufrenthi gidi va a<br /> Vift Nam, chiing t6i da th6ng ke ca mgt s6 loai cd the bimg phat mat dg, gay thiiy trieu do frong<br /> m6i trudng ty nhien, tir do gay hai tdi cac loai sinh vat biln nhu eac nhdm tao Thalassiosira,<br /> Chaetoceros, Skeletonema costatum, Ceratium, Gonyaulax, Dictyocha v.v.<br /> Hau het cac loai tao dgc hai da phat hifn dugc d vimg nghien ciiu diu thugc nhom tao song<br /> phii du (53 loai), ngoai ra con gap ea mgt s6 loai tao song bam day dien hinh (8 loai)tiiugccac<br /> chi Prorocentrum (P. lima, P. maculosum, P. emarginatum) va cac loai Gambierdlscus toxicu<br /> G. yasumotoi, Ostreopsis ovata, Coolia monotis, Amphidinlum klebsii. Day la nhimg loai tao<br /> thudng s6ng bam tren cac vat till day nhu rong biln, san h6 chet, nIn day eat biin.<br /> Trong danh sach tao dgc hai fren day, chiing t6i da b6 sung 3 loai so vdi cac nghien cihi<br /> trudc day [Larsen et al., 2004] do la Alexandrium foedum (gap d dim Lang C6), A. tamutum (cr<br /> dam Nha Phu) va loai Prorocentrum maculosum (d Cat Ba), trong dd loai P. maculosum co kha<br /> nang sinh dgc to DSP [Faust va cs., 1999].<br /> Tieu ban: C 6 N 6 NGHE SINH HQC BI^N VA M 6 I TRLfONG 495<br /> <br /> <br /> Ngoai ra, mot s6 loai tao giap ed kha nang sinh cac dgc t6 nhu Protoceratium reticulatum<br /> sinh dgc to yessotoxin [Miles et a l , 2005], Gonyaulax spinifera [Rhodes et al., 2006],<br /> Protoperidinium crassipes sinh dgc to AZP [Andersen, 1996] ciing thudng gap d vimg ven bien<br /> nude ta. va cac loai tao lam phan b6 trong ao nude Ig, d6i khi nd hoa nhu Microcystis spp. (sinh<br /> dgc td mycrocystin) vk Anabaena circinalis (sinh cac dgc to anatoxin va PSP) [Hallegraeff et al.,<br /> 2004] ciing da dugc thong ke vao danh sach tao dgc hai d vung nghien ciiu.<br /> Trong cac nam 2004-2005, thanh phin loai tao dgc hai thay d6i tiiy theo tiing vimg khao<br /> sat, trong dd khu vyc Do Son - Cat Ba gap 50 loai; tilp theo la dam Nha Phu (37 loai); dim<br /> Lang C6 (35 loai); Tiln Hai (29 loai); Binh Dai va Cin Gid cd so loai tuong ung la 14 va 18<br /> loai. Sy sai khac tren day cd the dugc giai thich nhu sau: ven biln Do Son - Cat Ba co cac loai<br /> binh thiiy vyc da dang, bao g6m ca viing cira s6ng (khu vyc D6 Son) co cac yeu t6 m6i trudng<br /> bien dgng manh va khu vyc Cat Ba cd dg man cao va 6n djnh ban. Mat khac dilm khao sat tai<br /> Cat Ba kha gan vdi cac ran san hd nen da bat gap ea cae loai tao dgc hai thudng s6ng tren loai<br /> hinh sinh thai nay, tuong ty nhu vay d6i vdi khu vyc Nha Phu. Trong khi do cac khu vyc Tien<br /> Hai, Binh Dai va Can Gid la nhimg viing cira s6ng dien hinh, nam rat xa vdi cac vimg ran san ho<br /> nen chi cd nhirng loai thich nghi dugc m6i trudng cira s6ng mdi cd mat. Trai lai, khu vyc dam<br /> Lang C6 kh6ng cd eac s6ng Idn vi the chi co nhimg loai ua dg man cao mdi phan b6 d khu vyc<br /> nay. Mgt ly do khac nira co the la tan xuat khao sat tai khu vyc Do Son - Cat Ba cao hon (2<br /> lan/thang) trong khi cae vimg eon lai chi tien hanh 1 thang/1 lan.<br /> Nhom lodi phdn bo rpng: bao g6m cac loai phan b6 rgng ve mat dja ly, hifn difn d hau het<br /> cac khu vyc thu mau tir Bac den Nam, dd la Dinaphysis caudata, D. miles, Prorocentrum<br /> micans, Pseudo-nitzschia spp., Gonyaulax spinifera, G. polygramma, G. verior, Noctiluca<br /> scintillans, Dictyocha spp., Ceratium fusus, C. furca, Trichodesmium erythraeum, Skeletonema<br /> costatum, Thalassiosira, Chaetoceros, Alexandrium affine, A. leei, A. pseudogonyaulax va mgt<br /> so loai khac.<br /> Nhom lodi phdn bo h^p: gdm nhirng loai mdi chi bat gap d mgt khu vyc nhat djnh hoac<br /> frong mgt so loai vyc nude nhat dinh, do la Gambierdlscus toxicus, G. yasumotoi, Coolia<br /> monotis, Prorocentrum maculosum, Ostreopsis ovata thudng phan bd tren ran san h6;<br /> Microcystis spp., Anabaena circinalis phan b6 d cac vyc nude co dg man thap (nhu ao nu6i hai<br /> san) va mgt so loai mdi chi gap tai mgt s6 viing nhM Alexandrium foedum, A. tamutum.<br /> Cac kit qua nghien cuu da cho thay, tai mgt khu vyc nghien cuu s6 loai tao dgc hai bien<br /> dgng tiiy theo vyc nude, frong do cac viing nude ngoai de bien noi nude bien dugc trao d6i hang<br /> ngay thudng cd thanh phan loai da dang hon cae khu vyc nude tinh hoac it cd sy trao d6i nude<br /> nhu cae ao nuoi fr6ng hai san frong de, tham chi thanh phan tao dgc hai trong cac loai ao nu6i<br /> cung cd nhimg sai khac dang ke, cu the la ao nudi tham canh cd thanh phan loai ngheo nan,<br /> frong khi s6 loai tai ao nu6i quang canh va viing nude ngoai de gan giong nhau. S6 loai tao dgc<br /> hai hifn difn tai timg khu vyc nghien ciiu bien dgng kha manh theo thcri gian frong nam. 0 ven<br /> biln mien Bic, cac thing miia mua va dau miia kh6 (tir thang 5 din thang 10) co so loai tao dgc<br /> da dang hon, trong khi d6 tai khu vyc mien Trung s6 loai dugc tim thay cao nhat vao cac thang<br /> miia khd cua thdi ky gio miia Tay Nam va giam vao thdi ky chuyen tiep gid miia. Tuy vay, ciing<br /> CO thi thiy sy phong phu ve thanh phan tao dgc hai trong thdi ky manh cua gid miia D6ng Bac<br /> (thang 1). Rieng khu vyc Nam Bg, vao cac thang tir thang 3 den thang 6 co s6 loai phong phii<br /> ban thdi gian con lai.<br /> 496 Tuyln t&p HQi nghj KHOA HQC T O A N Q U 6 C V £ SINH HQC BI^N VA P H A T TRifeN BfeNVfni/,<br /> <br /> <br /> <br /> 2. Phan bo tao doc hai d cac viing nuoi trong thuy san tap trung ven bien Vift Nam<br /> <br /> 2.1. Nhom lodi tdo sinh dgc to PSP !<br /> Thanh phin loai va bien dgng mat do tl bao tao Alexandrium thay ddi tiiy tiieo thdi gjan<br /> va khu vyc nghien ciiru, cy thi nhu sau: Tao Alexandrium la nhdm loai phan b6 rgng, co the g$n<br /> chiing frong cac thuy vyc ven bd tir Bac den Nam, tir cac vyc nude nuoi hai sanfrongde (cdc ao<br /> dim nu6i t6m) tdi vimg nu6i hai san ngoai de (cac bai nu6i DVTMHMV, khu nu6i ca long...).<br /> Thdi gian ma tao Alexandrium gap ph6 biln dien ra kha rai rac tiiy theo timg khu vyc va tiing<br /> loai cu thi. Tuy nhien, ciing cd the thay co mgt s6 thdi diem thudng gap tao nay, do la vao<br /> khoang thing 2 va 3, cac vimg nudi ven bien tir Bac den Nam deu cd tao Alexandrium ^phaa bo.<br /> Dinh cao mat dg tao nay xuit hifn vao eac thing 7, 8 tai mgt so ao nudi tdm thugc Do San, LSng<br /> C6 va Nha Phu, trir Tiln Hai mdi chi gap chiing d viing nude ngoai de. Trong qua trinh khao sit<br /> da phit hifn loai A. pseudogonyaulax nd hoa tai ao nu6i tom d Nha Phu vdi mat dg cao nhat d?t<br /> tdi 2,36.10' TB/L vao thing 8/2004. Chua phit hifn thay anh hudng cd b^i nao ciia sy bimg pMt<br /> tao A. pseudogonyaulax tdi t6m nu6i frong thdi gian nd hoa, mac dii cd sy gia tang ham lirgng<br /> ammonia va nitnc frong nude cua ao nudi.<br /> <br /> 2.2. Nhom loai tdo sinh dgc to DSP<br /> Nhin chung, tio D. caudata hifn difn gan nhu quanh nam d vimg nghien ciru, tuy nhien s\r<br /> phan bd mat do cua tao nay kb6ng d6ng deu va bien dgng khi manh theo vimg dja ly va thfiri<br /> gian frong nam. Xu the phan b6 cua tio D. caudata tai hai khu vyc D6 Son va Tien Hai gan<br /> tuong ty nhau, chiing thudng pho hifn tir thing 8 den thing 4 va deu xuit hifn dinh cao vl m(it<br /> dg frong cudi miia kh6 (thing 3 va 4), frong khi do tai khu vyc Cit Ba lai thudng gap vao mua<br /> mua (tir thing 5 den thing 8) va cd mit do cao hon frong cic thing 6 df n thing 8. Tai khu vyc<br /> Nam Trung Bg va D6ng Nam Bg, trong khi d Dam Nha Phu tao niy ph6 bien vao thing 9 vi<br /> thing 10 thi tai Can Gid chiing lai thuong gap tir thing 7 den thing 11. Rieng hai khu vyc Dam<br /> Lang C6 va Binh Dai, tio niy co mat dg rat thap. Ding chii y la tai cic ao nu6i hii sin thupc 7<br /> vimg nghien cuu, tio D. caudata cd mat do rat thip, tham chi kh6ng gap. Trong thdi gian nghien<br /> ciiu, phan Idn tio nay diu co mat dg dudi 500 TB/L, ngoai trir tai Tien Hii (thing 3/2005) va<br /> Dim Nha Phu (thing 10/2004) chiing co mat do dat tdi 600 TB/L.<br /> <br /> 2.3. Nhom lodi tao sinh dgc to ASP<br /> Tir cic ket qui khio sit trong cic nam 2004, 2005, ket hgp vdi vifc phan tich, so sinh vdi<br /> cic nghien cuu gin day ve tao Pseudo-nitzschia tai mgt s6 vimg ven biln Vift Nam, e6 the dua<br /> ra nhan xet chung ve phan b6 cua tio nay nhu sau:<br /> O vimg ven bd phia Bac, tao Pseudo-nitzschia thudng chiem uu the va dat mat dg cao nhat<br /> frong khoing thdi gian tir tiling 1 din thing 3 hing nam. Ngoai ra, tuy theo timg nam ma tio<br /> Pseudo-nitzschia cung cd the hinh thanh cic dinh cao vio thing 8 va thing 10,tiiynhien m^t dp<br /> thudng thap hon thdi dilm diu nam.<br /> 0 vimg ven bien Trung Bg, tao nay thudng xuit hifn vdi mat dg kha cao vao cactiiangH,<br /> 12. Thdi gian con lai chiing co mat dg khdng ding kl.<br /> Vimg ven bien D6ng Nam Bg, tio Pseudo-nitzschia chii ylu phan bo frong cictiiangtir<br /> thing 2 den thing 5/2005,friynhien mat do cao nhit chi dat khoing vai nghin tl baofrenlit, cac<br /> thing khic tao nay co mat do rit thip.<br /> Ti^u ban: CONG NGHE SINH HOC Bl^N vA MOI TRLf6rNG 497<br /> <br /> <br /> <br /> Nhin chung, tio Pseudo-nitzschia thudng phat friln vdi mat dg cao d vung ven bd phia Bac<br /> vdi mat do dat tdi hang trifu te bao frong mgt lit nude biln, trong khi do cic vung khac co mat<br /> do thap ban, cao nhit cung chi dat khoing 10''-10^ TB/L.<br /> Sy phan bo cua tio Pseudo-nitzschia theo cac loai hinh thiiy vyc tuong doi rd ring, chiing<br /> chu yeu phan b6 vdi mat do cao trong cic loai hinh thuy vyc ty nhien (vimg bai trieu, ciia s6ng,<br /> ven bien) hon la trong cic ao nu6i trong hai sin, noi chiing xuat hifn vdi mat do thap.<br /> <br /> 2.4. Nhom lodi tdo sinh dgc to khac<br /> Mgt sd loai tio khac cung cd khi nang sin sinh cic dgc td microeystin, CTP, AZP,<br /> yessotoxin, ciguatera toxins v.v. nhu vi khuan lam Microcystis spp., Trichodesmium spp., cic<br /> loai tao giap Prorocentrum minimum, Gonyaulax spinifera, Protoperidinium crassipes, Lingulo-<br /> dinium polyedrum, Gambierdlscus yasumotoi, Coolia monotis, Ostreopsis ovata, Amphidinlum<br /> klebsii, Prorocentrum lima... cung da dugc phit hifn d vung nghien cihi.<br /> Chi Prorocentrum: Day la nhom loai phan b6 rgng, gap hau bet d cic vimg ven bien tir Bac<br /> den Nam, trong dd cic loii thudng gap nhat phii ke den li P. micans, P. cf. rhathymum va P.<br /> minimum. Mgt sd loii tao sdng bim diy (P. lima, P. emarginatum) cung da dugc phit hifn tai<br /> vimg ven bien mien Bac vi mien Trung. Cic loai niy thudng gap tren cic ran san h6, co bien vi<br /> rat it gap trong cic ao nuoi trong hii sin. Trong chi tio Prorocentrum ding chii y la loai P.<br /> minimum vi frong qui trinh khio sit da bat gap hifn tugng bimg phit mat do ciia chiing tai mgt<br /> s6 ao nu6i t6m ven bien phia Bac (D6 Son, Lang C6) vio cic thing 12 v i 1 trong nam. Ngoai ra,<br /> loai P. cf. lima phan b6 vdi mat dg khi cao (tir 5.10^ den 5.10''TB/L) vao cic thing 5, 6, 7/2004<br /> ciing da dugc ghi nhan tai ao nudi t6m Lang C6. Vi cic loai tio tren co the bimg phit mat dg<br /> frong ao nu6i nen chiing cd the li tic nhan gay nii ro tdi cic d6i tugng hii sin nu6i frong thiiy<br /> vyc nay.<br /> Tao lam hay Vi khuin lam (Cyanobacteria): Tio Trichodesmium spp. li nhdm loai phan b6<br /> rgng, gap c i trong moi trudng nude Ig den nude man khap ven bien nude ta. Trong nam chiing<br /> thudng phit triln vdi mat dg cao, tham chi gay hifn tugng thuy trieu dd khi pho bien d vimg bien<br /> miln Trung va nam Trung Bg trong thdi gian tir thing 3 den thing 9. Ngoii ra, frong ldp vi khuin<br /> lam edn cd mgt sd nhdm loai rat ding quan tam nhu cic loii Microcystis spp., Anabaena spp. va<br /> Oscillatoria spp. ciing thuong gap tai mgt so vimg nghien ciru vao nhiing thdi diem nhat djnh.<br /> Day la nhdm loai thuong phin b6 trong cic thuy vyc nude nggt hoac nude Ig. Vi the cic ao nudi<br /> nude Ig la mdi trudng khi thich hgp doi vdi cic loai tio tren. Tio Microcystis spp. da bimg phat<br /> so lugng vdi mat dg khoing 6.10" tap doin frong 1 lit, ude tinh dat tdi hang chyc trifu te bio fren<br /> lit vao thing 9/2004 tai ao nudi l6m D6 Son, tuy nhien chua phit hifn thay t6m, c i chet frong ao<br /> niy. Loai vi khuin lam Oscillatoria lemmermannii co mat hau bet cac thing frong nam tai khu<br /> vyc Binh Dai. Loai niy dat s6 Unrng cao nhat frong miia mua (cic thing 7, 8, 9) tai cic diem<br /> frong ao nudi tdm va kenh dan nude, trong do mat dg cao nhat (khoing 2.10^ TB/L) bat gap vao<br /> thing 8 v a t h i n g 11/2004.<br /> <br /> 2.5. Bien dgng so luang cua cdc nhom tdo co khd nang gdy Itgi<br /> Trong so 61 loii tio dgc hai dugc phit hifn d vimp nghien ciru co khoang 20 loai thugc<br /> nhdm tao gay hai. Day li nhom icii khonp co khii n.\ng smh cic dgc to nhung khi biing phit co<br /> thi gay nen hifn tugng thiiii iM>^<br /> <br /> <br /> <br /> spp., Chaetoceros spp. Do vay, cin phii dua chiing vio danh sach cic loai tio can phai quan<br /> frac, giim sit.<br /> Skeletonema costatum: Day la loai tao phan b6 rgng khip vimg ven biln nude ta va co the<br /> gap chiing trong cic vyc nude nuoi t6m cung nhu ngoai bien. Trong nam chiing thudng phit<br /> tiiln tao thinh hai dinh cao vl mat df do la vao khoing thing 2-3 va cic thing 7 din 10. Do tao<br /> S. costatum co thi bimg phat vdi mat dp cao trong m6i trudng ven bien nen day la d6i tugng can<br /> phii dugc kiem soat.<br /> Thalassiosira spp.: Tao Thalassiosira phan b6 khi pho bien d vimg ven bien nude ta. Tji<br /> vimg nu6i fr6ng hii san Do Son-Cit Bi chiing phan bo quanh nam. Nhin chung, xu the phan bo<br /> ciia tao nay tai viing nghien ciru la phit trien tao thinh dinh cao ve mat do vao cic thing miia<br /> mua, frong do khu vyc D6 Son co mat dg thap hon khu vyc Cit Ba. Tuy vay, mat dg ciia chiing<br /> mdi chi dat fren dudi lO" TB/L. Tai cac vimg nudi hai sin Can Gid va Binh Dai mdi chi bit g$p<br /> tio Thalassiosira spp. phan b6 vdi mat do khi cao (3.10^ TB/L) frong ao nu6i t6m khu vyc Can<br /> Gid vao thing 7/2004. Cic khu vyc khac chiing cd mat do khong ding ke.<br /> Chaetoceros spp.: Nhom tao nay phan b6 rgng khap d viing nghien cuu. Sy phan bo m^t dp<br /> tio nay tai cic thuy vyc ciing co nhieu sai khic. Trong cic ao nudi, tio Chaetoceros co m^t dp<br /> kh6ng cao. Day la nhom loai co the gay chet c i va dgng vat an lgc do cau tao te bio tao c6 nhieu<br /> 16ng gai nen de gay tic mang cic dgng vat nay.<br /> Ceratium spp.: Ci viing ven bien Vift Nam, loai tio Ceratium furca phan b6 khi pho bien<br /> frong hau het cic thing trong nam. Tiiy timg khu vyc nhat djnh ma tio niy c6 mat dp phan bo<br /> khic nhau. Trong cic nam 2004, 2005, khu vyc D6 Son - Cit B i cd mat do tio C. furca khong<br /> qui lO" TB/L, frong khi do tai vimg nu6i ngao Thii Binh, mat dg cao nhit cua chiing d?t tdi<br /> 1,52.10^ TB/L (thing 4/2005). Trong ao nu6i t6m, tio nay cd mat dg lch6ng ding kl. Sy phan bo<br /> mat do tao C. furca thay doi tiiy theo timg khu vyc v i thdi diem cy thi. Cic ket qui nghien curu<br /> cho thiy, day li loai co khi nang bimg phit mat do gay nd boa d vimg ven biln Vift Nam. Do<br /> vay, can phii dua chiing vio danh sich cac loii quan frac, giim sit.<br /> Ngoai ra, tai mgt s6 dja diem nghien ciiu, tuy timg thdi dilm nhat djnh eon co die gap mpt<br /> so loai tao khac cung xuat hifn vdi mat do khi cao, cu the nhu trong ao nu6i D6 Son tao<br /> Nitzschia sigma co mat dg xip xi 3.10^ TB/L (7/2004), Melosira sp. dat 10^ TB/L (9/2004), tao<br /> giip Proto-peridinium spp. Dat 1 0 ' ' T B / L (cac thing 6, 8 v i 10/2004), Peridinium quinquecorne<br /> dat 2,9.10''TB/L (thing 10). Tai Cit Ba, vao cic thing 5, 8, 9 va 12/2004, loai Thalassionema<br /> spp. CO mat dg dao dpng tir lO" din 3.10"TB/L.<br /> <br /> IV. KET LUAN<br /> <br /> Ve thanh phan loai va phan bo tio dgc hai tai cic viing nuoi frong hii sin tap trung ven bien<br /> Vift Nam, budc diu da xic djnh dugc loii 61 loai va nhdm loii thugc 25 chi, 4 ldp tio. Trong<br /> do ldp tio giip (Dinophyceae) gap 47 loai, 16 chi (chiem 77% tong s6 loai); ldp tao silic<br /> (Bacillariphyceae) co 8 loai vi nhom loai, 5 chi (13,1%); ldp t i o lam (Cyanophyceae) co 4 loai,<br /> 3_chi (6,6%) va ldp tao Kim (Dictyochophyceae) gap 2 loai, 1 chi (3,3%). Chi Alexandrium c6<br /> s6 loai phong phu nhit (14 loii), hai chi Dinaphysis va Prorocentrum, 'm6i chi gap 7 loai, cac chi<br /> con lai gap tir 1 din 3 loai. Da phit hifn b6 sung 3 loai mdi (Alexandrium foedum. A. tamutum<br /> va Prorocentrum maculosum) cho khu hf vi tio biln Vift Nam.<br /> Ve phan bo s6 loai tio dpc hai d vimg nghien ciru: d ven biln D6 Son - Cit Ba da gap 50<br /> loai, Dam Nha Phu (37 loai); Dim Lang Co (35 loii); Tiln Hii (29 loai); Binh Dai va Can Gia<br /> CO so loai tuong ung la 14 va 18 loai. Phin Ion cic loai tao da phit hifn thugc nhom tao song<br /> phu du (53 loai), nhom tao song bam day chi gap 8 loai.<br /> Tieu ban: CONG NGHE SINH HOC BI^N VA MOI TRLTONG ^ ^22.<br /> <br /> <br /> <br /> Tao Alexandrium (sinh dgc to PSP) la nhom loai phan bo rgng d ven bien tir Bac den Nam,<br /> vdi dinh cao mat do bit gap vao cic thing 7, 8 tai ao nuoi t6m D6 Son, Lang C6 va Nha Phu,<br /> mat do cao nhat ciia loai A. pseudogonyaulax dat 2.1 O^TB/L (d Nha Phu vao thing 8/2004).<br /> T i o Dinaphysis caudata (sinh dgc t6 DSP) li loii ph6 biln nhit, hifn difn gan nhu quanh<br /> nam d vimg nghien ciru, tuy nhien sy phan b6 mat do cua tao nay kh6ng d6ng deu v i bien dgng<br /> khi manh theo viing dia ly v i thdi gian frong nam.<br /> Tao Pseudo-nitzschia (sinh dgc to ASP) thudng chiem uu the trong cic thuy vyc ty nhien<br /> v i dat mat dg cao nhat tir thing 1 den thing 3 hang nam hoac vao thing 8 va thing 10 d vimg<br /> ven bien phia Bac, vao cac thing 11, 12 d ven bien Trung Bg va tir thing 2 den thing 5 d ven<br /> bien Dong Nam Bg.<br /> Mgt so loai tio khac ciing co khi nang sin sinh cic dgc t6 microeystin, CTP, AZP,<br /> yessotoxin, ciguatera toxins v.v. nhu cic loai Microcystis spp., Trichodesmium spp., mgt sd loii<br /> thugc cac chi Prorocentrum, Gonyaulax, Protoperidinium, Lingulodinium, Gambierdlscus,<br /> Coolia, Ostreopsis, Amphidinlum... va mot so loai tao gay hai nhu Skeletonema costatum,<br /> Thalassiosira spp., Chaetoceros spp. cung da dugc phit hifn d vimg nghien cim, trong do ding<br /> chii y la cac loai Microcystis spp., Prorocentrum minimum. P. cf. lima, Oscillatoria lemmer-<br /> mannii thudng bimg phit mat do frong mgt so ao nuoi d Do Son, Lang C6 va Binh Dai vao cic<br /> thdi diem khic nhau frong nam.<br /> <br /> V. TAI LIEU THAM KHAO<br /> 1. Andersen P., 1996. Design and implementation of some harmful algal monitoring system.<br /> IOC Technical Series No. 44. UNESCO, 102 pages.<br /> 2. Faust M. A., Larsen J. and Moestrup 0 . , 1999. Potentially toxic phytoplankton, 3. Genus<br /> Prorocentrum (Dinophyceae). Intemational Council for the Exploitation of the Sea. ICES<br /> identification leaflets for plankton. Leaflet No. 184-ICES: 1-23.<br /> 3. Hallegraeff G. M., Anderson D. M., Cembella A. D., 2004. Manual on Harmflil Marine<br /> Microalgae. Monographs on oceanographic methodology 11. UNESCO, 793 pages.<br /> 4. Larsen J. and Nguyen N. L. (Eds.), 2004. Potentially toxic microalgae of Vietnamese<br /> waters. Opera Botanica 140, Copenhagen, 216 pages.<br /> 5. Miles C , Samdal A. I., Aasen J. A. G., et al. 2005. Evidence for numerous analogs of<br /> yessotoxin in Protoceratium reticulatum. Harmful Algae (in press).<br /> 6. Rhodes L., McNabb P., de Salas M., et al. 2006. Yessotoxin production by Gonyaulax<br /> spinifera. Harmful Algae 5(2): 148-155.<br /> 7. Soumia A. (Eds), 1978. Phytoplankton manual. UNESCO, 337 pages.<br /> <br /> D I S T R I B U T I O N OF H A R M F U L POTENTIAL M I C R O A L G A E IN S O M E<br /> F I S H E R Y C U L T U R E AREAS IN C O A S T A L W A T E R S OF V I E T N A M<br /> <br /> Chu Van Thuoc et al<br /> <br /> SUMMARY<br /> <br /> During the survey in 2004-2005, a total of 61 species of harmful potential marine microalga<br /> belon