S ha bi Trung tm Hc liu - HTNhttp://www.lrc-tnu.edu.vn/ B GIO DC V O TO V CNG NGH VIT NAM I HC THI NGUYNVIN SINH THI V TI NGUYN SINH VT CAO VN LNG NGHIN CU C IM SINH HC LOI C XOAN Halophila ovalis (R.Br.) Hook. f. TRONG M NUI THY SN HUYN CT HI (HI PHNG) V KH NNG NY MM CA HT TRONG PHNG TH NGHIM LUN VN THC S KHOA HC SINH HC CHUYN NGNH: THC VT HC M S NGNH: 60420111 NGI HNG DN KHOA HC: TS. M C TIN H NI, NM 2013 S ha bi Trung tm Hc liu - HTNhttp://www.lrc-tnu.edu.vn/ LI CM N hon thnh chng trnh cao hc, ti nhn c s hng dn v gp nhit tnh ca qu thy c thuc Vin Sinh thi v Ti nguyn Sinh vt (thuc Vin Hn Lm Khoa hc v Cng ngh Vit Nam) v trng i hc Thi Nguyn.Ti xin gi li bit n su scn Tin s m c Tin dnh rt nhiu thi gian v tm huyt hng dn khoa hc v gip ti hon thnh lun vn tt nghip. ngthi,tixincmnquanh,chngnghipvbanlnho VinTinguynvMitrngbin(thucVinHnLmKhoahcv Cng ngh Vit Nam) ni ti cng tc, to iu kin thi gian v c s vt cht hon thnh nhng ni dung nghin cu. Xin gi li cm n n ti c s: Nghin cu kh nng trng bng htloicXoan(Halophilaovalis(R.Br.)Hooker,1858)phngth nghim; ti: Nghin cu hin trng mi trng, bin ng ngun li, a dng sinh hc h sinh thi vng triu ven bin min Bc Vit Nam (t Qung Bnhtrra), xutmhnhkhai thc, nuitrng, botnvqunlbn vng v d n:iu tra cc loi thc vt thy sinh bin c kh nng hp thCO2gimhiungnhknh,chngbinikhhutoiukin cng tc v ti tr kinh ph cho ti kho st c d liu vit lun vn. Mc d ti c nhiu c gng hon thin lun vn bng tt c s nhit tnh v nng lc ca mnh, tuy nhin khng th trnh khi nhng thiu st, rt mong nhn c nhng ng gp qu bu ca qu thy c v cc bn. H Ni, thng 12 nm 2013 Hc vin LI CAM KT S ha bi Trung tm Hc liu - HTNhttp://www.lrc-tnu.edu.vn/ Ti xin cam kt y l cng trnh nghin cu ca ring ti. Cc s liu, kt qu nu trong Lun vn l trung thc v cha c cc tc gi khc cng b trong bt k cng trnh no. TixincamktmisgipchovicthchinLunvnny c cm n v cc thng tin trch dn trong Lun vn c ch r ngun gc. Hc vin thc hin Lun vn S ha bi Trung tm Hc liu - HTNhttp://www.lrc-tnu.edu.vn/ MC LC trang Trang ph ba Li cm n Li cam kt Mc lc Danh mc cc bng Danh mc cc hnh M U1 Chng I TNG QUAN4 1.1. Tnh hnh nghin cu c bin trn th gii4 1.2. Tnh hnh nghin cu c bin Vit Nam13 1.3. Khi nim v c im hnh thi ca c bin16 1.4. Vai tr ca c bin18 1.5. Tng quan v iu kin t nhin, mi trng sng ca C bin18 1.5.1. Cht y18 1.5.2. mui20 1.5.3. Nhit 20 1.5.4. c20 1.5.5. nh sng21 1.6. Mt s c im t nhin vng nghin cu21 Chng II I TNG V PHNG PHP NGHIN CU23 2.1. i tng nghin cu23 2.2. a im v thi gian nghin cu24 2.3. Ti liu nghin cu25 2.4. Phng php nghin cu25 2.4.1. Nghin cu thc a25 S ha bi Trung tm Hc liu - HTNhttp://www.lrc-tnu.edu.vn/ 2.4.1.1. Thu mu sinh hc c bin25 2.4.1.2. Thu ht c bin26 2.4.2. Nghin cu trong phng th nghim27 2.4.2.1. Phng php nh loi27 2.4.2.2. m ht c bin27 2.4.2.3. Trng c bin28 2.4.2.4. Phn tch trm tch29 2.4.2.5. Quan trc mt s yu t mi trng 29 2.4.2.6. X l s liu29 Chng III KT QU NGHIN CU V THO LUN30 3.1. c im hnh thi ca loi c Xoan trong m nui thy sn30 3.1.1. Thn30 3.1.2. R30 3.1.3. L, phin l31 3.1.4. Vy l31 3.1.5. Hoa32 3.1.6. Qu v ht32 3.2. Mt s c im sinh thi ca loi c Xoan33 3.2.1. Mt s thng s mi trng trong m nui33 3.2.1.1. Nhit nc34 3.2.1.2. Cng nh sng34 3.2.1.3. Nng mui34 3.2.1.4. Nn y35 3.2.2. S bin ng theo ma ca c bin trong m nui36 3.2.2.1. Phn b v din tch36 3.2.2.2. Bin ng cc ch tiu sinh lng37 3.2.3. Ma ra hoa ca c Xoan42 S ha bi Trung tm Hc liu - HTNhttp://www.lrc-tnu.edu.vn/ 3.3. Kh nng ny mm ca ht c Xoan43 3.3.1 Kt qu thu ht 43 3.3.1.1. Thu trc tip trn cy43 3.3.1.2. Thu trong trm tch43 3.3.2. Kt qu m ht44 3.3.3. Kt qu gieo trng45 3.3.3.1. Hnh thi45 3.3.3.2. T l sng46 KT LUN V NGH47 DANH MC CNG TRNH CA TC GI49 TI LIU THAM KHO50 PH LC57 M U C bin (Seagrass) l nhm thc vt bc cao (ngnh Anthophyta, lp Monocotyledons, b Helobiae), sng trong mi trng nc mn v l. H sinh thi c bin (Seagrass ecosystem) l mt trong nhng h sinh thi in hnh ca vng bin nhit i (cng vi san h v rng ngp mn), c nng sut s cp cao, kh nng n nh nn y, tng hp cc cht hu c t v c, tham gia vo chui thc n, chu trnh dinh dng v l ni sng S ha bi Trung tm Hc liu - HTNhttp://www.lrc-tnu.edu.vn/ cho nhiu loi sinh vt c gi tr kinh t cao. Ngoi ra, trn cc thm c bin, con ngi thu c nhiu li ch trc tip v gin tip khc na [6]. Cho n nay, ti cc vng ven bin Vit Nam pht hin c khong 14loi c bin, trong c loi c Xoan - Halophila ovalis (R. Br) Hook. f. (thuc chi Halophila, h Hydrocharitaceae). V hnh thi, loi c Xoan tng igingrongbin(ccloithucchiCaulerpa)nhngthcchtlihon ton khc ch c bin l thc vt bc cao c thn, r, l, hoa v qu [8], [9], [11]. Chi Halophila l mt trong s t cc chi c lin quan ti ngun gc xut hinsmnhtcacbintrongqutrnhtinha[19].Halophilackh nngtntinhngvnglunbtcng,nhsngyuvccao. Halophilacvngphnbrngvgivaitrtinphongtrongkhnng mrngnhngvngbinsuhnviccloikhc[62].VitNam,chi Halophila c 4 loi, phn b tng i rng v c XoanHalophila ovalis l mt loi c bin nhit i phn b cc vng triu v c vng nc su [19], [38], [62] c sinh khi thp so vi cc loi khc [17], nhng li c chu k sinh trngnhanhhnccloiccbikchthcnhbcachng[22],[62]. Chu nhiu tc ng (ni c nhiu hot ng ca con ngi (nh thi, khai hoanglnbin,xydng,v.v)vcctcngbtlitthinnhin(nh sng, dng chy, ph sa, v.v) nn din tch phn b ngy cng b thu hp. Ti mt s vng trc kia c c Xoan th n nay hu nh khng cn na [9]. cc vng ven bin ng Nam , cc nghin cu cho thy cc thm c binangdnbinmt.Indonesiakhong30-40%ccthmcbinb mt trong khong 50 nm qua, trong ring Java b mt khong 60% [58]. Philippin cc thm c bin b mt khong 30 50%, cn Thi Lan, con s nykhong2030%.VitNamcngkhngnmngoitnhtrngtrnvi 50% tng din tch c bin bin mt trn khp cc vng ven bin c nc [6]. S ha bi Trung tm Hc liu - HTNhttp://www.lrc-tnu.edu.vn/ CtHilmthuynothucthnhphHiPhng.Trongnhng nm trc y (trc 1995), c th thu c mu c Xoan ti nhiu ni (trong v ngoi m nui trng hi sn) nhng n nay, c Xoan ch cn thy trong mt s m nui. Kt qu nghin cu v c bin (ni chung) v c Xoan (ni ring) nc ta cha nhiu v ti Ct Hi th hu nh cha c. Mt vi cng trnh v c bin ti Ct Hi ch yu nghin cuv thnh phn loi, phn b cha nghin cu v c im sinh hc, ma v, sinh sn,...[1], [10]. Vicphchicchsinhthitrncncnghincutluv ang cmt skt qu khtt,nhng phc hicch sinhthi dinc, nht l bin mi ch c bt u trong vi thp nin gn y. Phc hi h sinh thi c bin cn gp kh khn hn nhiu do c bin thng phn b ti ccvngnc nngvenb,nic nhiuhotngcaconngi(nh thi, khai hoang ln bin, xy dng, v.v) v cc tc ng bt li t thin nhin (nh sng, dng chy, ph sa, v.v). Mt kh khn na khi trng phc hi c bin bng chi l kinh ph rt tn km, kh thc hin trn din rng v khng ngungingcungcpvhiuqu thp.Hn na,phng php trncn lmnhhngkhngnhtibicbinhinc.Victrngbnghtcc loicbincrtnhiuuthvcthtrngctrndintchrng, nhng vic trng phc hi cc thm c bin bng ht cha cnghin cu nhiu hoc mi mc tng. Kt qu nghin cu v mt s c im sinh hc, sinh thi, bin ng theoma,khnngchonymmhtloicXoansgpphnquantrng khng nhng trong vic b sung nhng hiu bit chung v h sinh thi c bin m cn c ngha rt ln trong vic trng phc hi loi ny ngoi t nhin. Chnhvth,chngtichnti:cimsinhhcloicXoan- Halophilaovalis(R.Br.)Hook.f.trongmnuithysnhuynCtHi- HiPhngvkhnngnymmcahttrongphngthnghimlmbo co cho lun vn tt nghip cao hc S ha bi Trung tm Hc liu - HTNhttp://www.lrc-tnu.edu.vn/ Chng I - TNG QUAN 1.1. Tnh hnh nghin cu trn th gii Vo u th k 20, vi s pht trin ca cuc cch mng khoa hc sinh hc, ln u tin c bin c cc nh khoa hc nghin cu ti trm Sinh thi hc Copenhagen, an Mch. Ngay sau , t c nhng thnh tu ng k. Trong , Ostenfeld (1905) v Pertersen v Boyer - Jensen (1905) l nhng ngi bc u m rng vic nghin cu sinh thi trn c ln [52], [53]. Nhng c im sinh hc v sinh thi ca c bin s quan tm ca cc nh khoa hc ngay t khi i tng ny c bit n. n nay, cng vic iu tra ngun li bin ny c m rng trn phm vi ton th gii, s lng cc cng trnh nghin cu v ang tng ln mt cch nhanh chng. Cng vic nh loi ca c bin ch yu da vo c im hnh thi ca cc c quan trn cy, nht l c quan sinh sn bi ngay trong mt chi cc loi thngchoakhcnhau.lmciu,phiknDenHartog (1970), Phillips v Meez (1988) l nhng nh phn loi hc c bin. H cnhngnggptolntrongvicnghincuvsinhthihccbin. iu th hin haicun sch v hthngphn loi:Cbin thgii- The seagrass of the world ca DenHartog (1970) vC bin- Seagrass caPhillips vMeez(1988).Ccnh phnloihcaracnhng c im c bn phn loi c. H thng phn loi c bin ch yu da trn ccc im chung ging nh vi thc vt c hoa khc nh: cm hoa, hoa, qu, ht, h gn l, cht tanin, rng ca mp l v nh l... [15], [53].Xc nh h thng phn loi c bin l rt cn thit, n l tin cho cc hng nghin cu v c bin cc kha cnh khc nhau ca h thc vt bin ny. Do khng th ch da trn vic gii phu hnh thi m ngy nay ngi S ha bi Trung tm Hc liu - HTNhttp://www.lrc-tnu.edu.vn/ tacndatrnditruynhc,phntchphnt[29].lbctinmi trongkhoahcsinhhcnichungvtrongnghincucbinniring. Nhiu tc gi cng c nhng bt ng v s loi thuc ba chiHalophila, Zostera v Posidonia [29]. Qu tht, khi s dng phng php nh du phn tLesvcngs(1997)nhnthyskhcbitvditruyngia HeterozosteravZosteragingviccloithucchiZostera,iucho thy 2 chi ny nn xc nh trong cng 1 chi [36]. Nhng cho n nay, iu ny vn ang tip tc bn lun v cn tip tc nghin cu. Cng c th do s phn b ca c bin rng khp trn a cu, nn n chu tc ng rt ln ca iukinalvcthdoiukintnhintcngnhnhthi ngoicacbin.Vvy,nghincucimditruynbnhimscth cachngphnloilrtcnthit.Vcncskthpgia hnh thi hcvditruynhcgiiquytccvncntntitrongnhloic bin.Nm 1950, c s thay i trong hng nghin cu v c bin vi mt bo co hon thin v s phn b v sinh thi ca c bin bang Florida (M). Sau bi bo ny, nhiu nh nghin cu bc u tp trung nghin cu cc thnh phn trong h sinh thi c bin nhit i. T nm 1960 n nm 1970 nghin cu c bin rng hn v m t nh tnh v cc nghin cu v nh lng. Cc quan nim v h sinh thi c bin c hon chnh v y hn. Mt nghin cu s v c Ln Alaska c hon thin vo nm 1966 bi McRoy [53].Vi s pht trin nhanh chng ca khoa hc c bin, th cn phi c s phihp,traoikinhnghimvkinthcgiaccnhkhoahcnghin cu v c bin. Do vy, ln u tin mt cuc hi tho quc tc t chc vo nm 1973 ti Leiden, H Lan, do Vin Khoa hc Quc gia H Lan ti tr, bao gm 38 nh khoa hc t 11 nc trn th gii. Hi tho ny ch yu a S ha bi Trung tm Hc liu - HTNhttp://www.lrc-tnu.edu.vn/ ranhngktquvtholunvnhngnghincucthchinv nhngkinnggpvnhngvnslmtrongtnglai.Tsauhi thoquctny,slngcccngtrnhnghincucbintngln nhanh chng nhiu ni trn th gii c bit Nht, c, Php, H Lan, n , Canada, Papua New Guinea v Phillipine. V cho n nm 1978, cc nh khoa hc lit k c mt th mc sch tham kho v nghin cu sinh thi cbinbaogmhn1400bitrntonthgii[64].Vonm1982,mt phn tch v c bin NamFloridabaogmhn 550 tiliu thamkho [53]. iu chng t rng s lng cc nghin cu v c bin tng ln nhanh chng. V t cuc hi tho v h sinh thi c bin ln th I Leiden, H Lan cho n nay, th cc cuc hi tho quc t v c bin ln th II, III v th IV na ln lt c din ra. Vo nm 1998 - nm quc t i dng, hn 100 nh khoa hc tp trung ti cuc hi tho c bin ln th III c tchctiPhilippine.Hithovcbinvonmquctidng phnnhcstrngthnhcakhoahccbinvnhngtincho vic qun l h sinh thi quan trng nyv nhng viccn lm trong tng lai.Shptcchtchgiaccnhkhoahctrnthgii,stolpmt mng li nghin cu trn ton cu l mc tiu ca cuc hi tho quc t ln th IV vo nm 2000 ti o Corsica, Php. Nhng cuc hi tho nh vy thu ht c s quan tm ca cc nh khoa hc, nht l cc nh khoa hc tr mun i su nghin cu hn na.Kin thc v c bin ngy cng c m rng v nng cao th hin s lngccbibovcbinccngbngycngnhiutrncctptr ln trn th gii [20]. Trong nhng nm gn y, mi nm c khong 100 bibocxutbn,nhngchyutptrungmtstptrlnnh: Thusinhhc(AquaticBotany),SinhthihcBin(MarineEcology ProgressSeries)vTpchSinhhcvSinhthiBin(Journalof ExperimentalMarineBiologyandEcology).Tuyslngcccngtrnh S ha bi Trung tm Hc liu - HTNhttp://www.lrc-tnu.edu.vn/ nghin cu tng ln nhng cha ng u. Cc nghin cuch yu tp trung cc nc pht trin, nht l Chu u cn cc nc ang pht trin th c bin thc s l mt i tng mi m, cha c s quan tm ng n ca cctchcchnhphvphichnhph[20].Vvy,trongnhngnmgn y, c nhiu d n phi hp gia cc nc c nn khoa hc c bin pht trin vi nhng nc ang pht trin nhm o to cc nh nghin cu tr cho cc nc ny to kh nng bo v v qun l ngun li thc vt bin v c cmtmnglinghincuhsinh thi c bin honthinhn trn toncu.Trong,VitNamcnglmttrongnhngncngNam bc u c s trao i sinh vin trong o to v sinh thi c bin vi cc nc trong cng ng Chu u v cc nc trong vng c h sinh thi thc vt bin ny. Trong cc nghin cu v c bin, cc nh khoa hc nhn thy ngha sinhthicasbinngcutrcthn,r,tcsinhtrngvsphn nhnhca thncvcccquan khc. Vvy,c nhiu nghincu tp trungiu tratlsinh khi trnmtt (chi l vchi hoa)v sinhkhi dimtt(rvthn)cacbin.Trong,VerhagenvNienhuis (1983), m t s thay i c tnh ma v ca sinh khi trn mt t v sinh khi di mt t ca c ln bi k thut nh du trn l [62]. Xc nh sinh khi (sinh khi trn v di mt t) ca c bin v nh gi vai tr ca chng trong h sinh thi l rt quan trng [17], [51]. Trong h thn, r c l c quan gip cy sinh sn v tnh, mt thnh phn quan trng ca h sinh thi ny. Tuy nhin, Nelsson (1997) cho rng sinh khi trn v tng sinh khi c mi lin quan cht ch vi nhau, nhng sinh khi di th khng [48]. Kim tra sinh khi di c coi nh s nh gi kh nng m su vo trong nn y ca c binv iu cng c th c gii thch rng cc chi mi sinh ra cn nng lng t thn hn l nhng chi trng thnh [17], [64].Cc c quan bn di mt t gi vai tr quan trng trong dinh dng, c nh v S ha bi Trung tm Hc liu - HTNhttp://www.lrc-tnu.edu.vn/ pht trin ca c bin. S sinh trng v s phn nhnh ca thn nh hng n bin ng, sinh trng v tn ti ca qun th sinh sn v tnh [51]. iu rt cn thit trong mi trng bin, ni c nhiu tc ng n nhng bin ng ca h thc vt l v cng quan trng.Bncnhsduytrvphttrinqunthbngcchsinhsnvtnh bng thn chi, c bin cn sinh sn bng ht. Cch nh gi kh nng sinh sn ca c bin l s lng cc cy con c ny mm t ht vo ma ra hoa, hay s lng ht t cy m. Nhng ht trng thi ng di b chn vi trong nnyvckhnnghnhthnhngundtrmchophpnnymm trongiukinthchhpcgilngnhnght.Theonghincuca Hootsmans v cng s (1987), ht thng ny mm nhit cao v nng mui thp, v s ny mm s gim nhit thp v nng mui cao. V vy, c hin tng ng ng ca ht [30]. Vic th nghim di trng c bin trong phng th nghim c tin hnh t rt lu. Trc tin l nhng th nghim tm hiu kh nng pht trin ca c bin trong iu kin mi trng c kim sot v sau l trng c trong phng th nghim cho mc ch tm hiu kh nng ra hoa, to qu v ly ht. CthniSetchell(1924)[56]lngiutintrngcKim (Ruppia maritima)trong cc b sinh cnh. Sau , t thp nin 60 tr i, c nhiu cng trnh nui c bin nh Fuss v Kelley (1969) vKirkman (1989) nghin cu trng c Thalassia testudium c 12 thng trong b nui c nc bin chy lu thng [26], [32]. H lu rng thn ngm ca c bin pht trin chm v ngh ch dng phn nh cn non u ngn ca thn ngm (c thn ng) trng v h cng cho rng nui c ngoi tri, di nh sng t nhin thnh cng hn l nui trong iu kin nh sng n. Cc th nghim trngcbinquymtrongphngthnghimcthchinbi McMillan[39],[40],[41],[42],[43],[44],[45],[46]dngbnhadung tch 500 lt. Kt qu l h nui c bin c 2 nm, h nui th nghim S ha bi Trung tm Hc liu - HTNhttp://www.lrc-tnu.edu.vn/ cc loi c bin thng c hoa thuc 10 chi c bin khc nhau l: Thalassia, Thalassodendron,Syringodium,Halodule,Halophila,Enhalus,Zostera, Amphibolis,PosidoniavCymodocea.Ccthnghimnycnuingoi tri v c trong b sinh cnh (nh sng n in), nhm mc ch xem xt kh nngphttrinthnngm,thnng,ccsbinivhnhthivkh nng ra hoa, qu. Cc loi c ny c trng t c quan sinh sn sinh dng (thn ng, thn ngm) thu hi trong cc thm c ngoi t nhin. Yu t cht yrtquantrng.Ccthnghimdngnhiuloichtykhcnhau. Th nghimckt qu tt nhtivichtylctmncngun gc vi lc a ca bang Texas, cch vnh Mexico khong 300 km. S dng nc bin nhn to c mn 35 v nh sng nhn to c duy tr mc 8.000 40.000 lux. Nhit c iu chnh ging nh iu kin ni ly ging (18 - 300C). OrthvMoore(1983)kimtrasnymmcahtthngquas lng cy con thu c trong nm. Ti cng Thi Bnh Dng, s lng ht nymm cao nht trong thi im t thng 4 n thng 7, trong khi vng biniTyDngchaigiaionhtnymm.Giaionthnhtht ny mm vo cui thu, giai on hai c khong 66% ht ny mm t thng 12 n thng 3 nm sau. Cc cy con rt d b tn thng, t l sng l rt thp (xp x 2%) v c bin c t l sng dng c chai trong sut vng i ca n. Nghalckhong10%cytrngthnhrahoa,10%shoatrnshnh thnh qu, 1% - 10% s qu y c ht hnh thnh v 1% - 10% s ht trn s ny mm, 1% - 10% ht ny mm pht trin thnh cy con, cui cng ch c 10% s cy con trn pht trin trng thnh v ra hoa [49]. Ccyutvhnhdngngoivcccimsinhthi,sinhlca tng loi quyt nh phng php trng chng. C 5 mc tiu chnh c t ra cho vic nghin cu di trng v trng phc hi thm c bin l: - ph ca cc thm thc vt bin S ha bi Trung tm Hc liu - HTNhttp://www.lrc-tnu.edu.vn/ -Cn bng din tch bao ph ca cc thm thc vt v cc din tch phn b ca chng b suy gim hoc mt i -Gia tng din tch ca cc thm thc vt ny nu c th -Thaythngloichngtamongmunvocckhuvccbinb mt i -Sau cng l bo m s a dng sinh hc v pht trin cc qun x ng vt sng trong h sinh thi. C nhiu phng php di trng c bin nhng tng qut c th tp hp thnh 3 phng php chnh [16]:-o bng thn ng cng vi nguyn r v phn trm tch cn dnh vi r (phng php 1) -Dng ht (phng php 2) -Dng thn ng, thn ngm khng c r (phng php 3) phng php 1, c nhiu cch ly phn thn ng vi cng nguyn b r. i vi nhng loi c nh c th dng ng nha hoc ng kim loi cm xung bn ly, sau vn chuyn nguyn c khi ny t vo cc hc o sn ni nh di trng. Thun li ca phng php ny l mt lng ln thn ngm cn nguyn r v trm tch c di chuyn n ni trng mi lm cho c bin d thch nghi v pht trin, tuy nhin s bt li ca phng php ny l phi o h, lm c nc, xo trn ni c tr sinh vt, c th gy xi l, thm vo rt tn cng. Phngphp2,dnghtddnghnnhvicthuthpcccyc qu gn chnt ccbi c ngoi t nhin ri gi cc cy ny trong nc binchonkhihtcphngthch.Thunlicaphngphpnyl mt s lng ln ht thu c, kim sot c ngun ging, khng gy xo trnvvictrngcddng,nhanhchngtrnmtdintchln.Tuy nhinbtlicaphngphpnyltcngchccancbincth lm cho ht c b vi lp, di chuyn. S ha bi Trung tm Hc liu - HTNhttp://www.lrc-tnu.edu.vn/ Phng php 3, dng thn ng v phn thn ngm khng c r vi cc on ngn t 2 20 cm tu loi. Cc on thn ny c th c trng ring l hay ghp thnh nhm. C th dng mt on thp cm xung nn y nh l mt ci neo ci. Hoc 5 - 6 cy c th c buc chung ri neo cm xung y bng mt on thp. Lthcbccaotrongmitrngbin,khnngsinhsnbnghtl cch u vit trong vic bo tn ging cng nh vic pht tn v lan truyn cc thm c. S to hoa v qu ca cc loi c bin ph thuc vo nhiu iu kin mitrng,chyu lccyu tnhsng, nhit v mn.McMillan (1982),nghincuthcnghimTaxastrongcciukinchocc loi c bin phn b min Ty i Ty Dng v n - Thi Bnh Dng cthtohoavqu.CcchiHalodule,Thalassia,Syringodiumv Halophilaxuthincquansinhsntrongiukinchiusnglintcv nhitt20-260C.MtviloicachiHalophilachrahoanhit 260C [43]. C bin c tui th trung bnh t vi tun n hang chc nm, ph thuc vo kch thc ca tng loi. Nhng loi c c kch thc ln vi thn dy, l rng v r dy c th sng rt lu trong nhiu nm, nhng nhng loi c kch thc nh th thi gian sng ngn hn ch di mt thng. Do chu k sng ca chng rt ngn, nn nhng loi c c kch thc nh thng c kh nng ti sinh chi rt nhanh, v d kch thc c Halophila ovalis nh nhng chu k sng ca chng ch khong vi thng, cn Posidonia oceanica c th sng ti 11 nm [16].Cu trc ca c bin cn ph thuc vo c im vng phn b. Cc loi c kch thc nh thng mc trn cc vng triu, cn c c kch thc ln thng thy vng thp triu v di triu. Thm vo , c trn nn y nhiu ct c l hp hn c trn nn y nhiu bn. Hn na, vng nc nng l ni chu nh hng ca s thay i mi trng nhiu hn vng nc su. S ha bi Trung tm Hc liu - HTNhttp://www.lrc-tnu.edu.vn/ Thc vt sng vng nc nng thng b nh hng ca nh nng mt tri nhiu, trong khi thc vt vng nc su ch nhn c rt t [38]. Nhng kh nng chu tc ng v kh nng phc hi ca thm c bin vng nc su rt khc vi cc qun x c bin vng nc nng, chng c kh nng chng chu trc nhng cn bo nhng kh nng phc hi th chm chp. y l mt c trng rt in hnh i vi c bin vng nhit i [63]. C bin l thc vt ht kn sng hon ton trong mi trng bin. Nhng nhu cu v sinh trng cng ging vi thc vt ht kn trn cn. Tuy nhin, trong mi trng bin c bin vn c nhng khc bit v mt s c im i vi thc vt sng trn cn. Cc nh khoa hc u nht tr rng s phn b v s pht trin ca c bin b tc ng bi cc yu t mi trng. Tt c nhng bin i u rt quan trng i vi c bin. Cc yu t mi trng quan trng tc ng ln cc thm c bin nh nh sng, c, trm tch ... Trong , c bin b tc ng mnh bi hai nht t chnh l: nh sng v s lng ng trm tch. S sinh trng v pht trin ca c bin chu s chi phi ca nh sng, mt nhn t quan trng cho kh nng quang hp ca c bin. S phn b theo su ca c bin ch yu ph thuc vo thi gian chiu sng ngy. Vo thp k trc, cc nh nghin cu c bin tm hiu v kh nng quang hp ca c bin trong mi trng nc bin b hn ch nh sng. Cc tc gi i su nghin cu sn lng v sinh khi ca c v vai tr ca ch nh sng ln s sinh trng ca c [38]. Kh nng quang hp ca c bin c nghin cu trong phng th nghim i vi cc mc nh sng khc nhau [15]. nh sng khng ch b chi phi bi cao triu v c ca nc, m n cn chu nh hng bi mt thc vt biu sinh sng bm trn b mt ca phin l c. Hin tng ph dinh dng vng b bin H Lan ph hu cc thm c bin Z. marina v Z. noltii. Hin tng ph dinh dng kt hp vi s lng ng bn lm gim nh sng khuych tn ti cc thm c bin. Hn ch s pht trin ca c bin S ha bi Trung tm Hc liu - HTNhttp://www.lrc-tnu.edu.vn/ cng chnh lm gim cc yu t bo v cho nn y hay tng s xo trn nn y v vy gim nh sng l lm hn ch s pht trin ca cc thm c. Trong giai on t nm 1968 n 1981, hm lng chlorophyll tng ln gp i vng bin pha ty H Lan, v iu cng nh hng n thc vt biu sinh tng nhanh. Tt c nhng iu tc ng tiu cc n s quang hp v s sinh trng ca c bin gy ra s cnh tranh v cc-bon v ngun dinh dng lm gim st cht lng ngun li c bin [29].Cc loi c bin c kch thc nh thng rt d b tn thng di sc p ca nc v s lng ng trm tch. cng l mt trong nhng nguyn nhnlmgimkhnngphttrindintchmtcchnhanhchngcacc thm c bin vng bin ng nam Chu [24].S nhiu lon cc vng bin cng dn n cc thm c bin c h s a dng Shanon- Weaver thp hnsovicctchcthcvtbinkhc.Ccthmcbinthngln loi, vi h sadngthp nht l 0.Chs adngShanon-Weavercao (1,56) l thm c bin gm 7 loi vng bin Bolinao (Philippines), v ch s ln hn 1 l vng n - Thi Bnh Dng [29]. 1.2. Tnh hnh nghin cu Vit Nam VitNamlmtnccvngbbindihn3000kmthucvng binngNam,lnicsadngsinhhccaotrnthgii.Trong nhngnmgny,ngNamccoilvngckhnngphttrin nnkhoahcvcbinnhanhbisadngvthnhphnloi(nhtl Philippines, c ch s ang dng thuc loi cao 1,56) [9]. Cng nh cc vng bbinkhc,VitNamcngccchsinhthithcvtbinphongph, trongchsinhthicbin.Tuynhin,nhnghiu bit vh sinh thi ny vn cn hn ch v cha c s quan tm nhiu.S ha bi Trung tm Hc liu - HTNhttp://www.lrc-tnu.edu.vn/ Vicphthinvnghincucbintrcnm1960hontondo ngi nc ngoi thc hin. Nm 1885, Halophila ovalis c mt ngi nc ngoi tn l Balansa pht hin thy gn Qung Yn. Nm 1939, Tsang thu c mt loi c phin l di v mng H Ci- Qung Ninh, l phthinutinvloiZosterajaponicaVitNam;hailoiThalassia hemprichiivHalodulepinifoliactmthyCaB-KhnhHovo nm 1949 bi chuyn gia c bin tn l Deroux [9].Tnhngphthinbcuvscmtcamtsloicbin vng bin nc ta, nhng nh khoa hc trong nc cng bt u nghin cu c bin t nm 1960 tr v y. Phm Hong H ghi li nhng pht hin v c bin Qui Nhn (1960) v Ph Quc (1985) [9]. Tng s15 loi c bincphthinttrcnnay,nhngslngloithayigia3 min (min Bc 5 loi, min Trung 7 loi v nhiu nht l min Nam c 11 loi). Thnh phn loi gia ccmin cng khc nhau, c nhiu loi ch xut hin ti mt min m khng c ni khc. Vit Nam, cc hot ng gy mt hay suy gim cc thm c bin xy ra mnh khong hai thp nin gn y. Theo thng k, din tch cc thm c bin ca nc ta gim i 40 60% (ring vng bin Hi Phng, ni m cc hot ng nui thy sn, du lch v xy dng xy ra mnh m, cc thm c bin ny gn nh bin mt) [1], [2], [3], [6], [9], [10]. Cc loi c bin u c th sinh sn bng ht (sinh sn hu tnh) v bng chi(sinh snsinh dng).Cho nnay,tiVitNamc nghincu v trngphchicbin(trngbngchi)vktqubcutccn hn ch, v phn ln cc bi c bin c trng phc hi u b tn ph bi con ngi v t nhin [1], [8]. Vic di trng c bin ln u tin thc hin vi loi c l DaEnhalus acoroides. Loi ny c di trng trong t nhin vng m Gi, Hn Tre, vnhNhaTrangvkhuvcgncngCu,NhaTrang,trongkhunkh S ha bi Trung tm Hc liu - HTNhttp://www.lrc-tnu.edu.vn/ th nghim nh [1]. Khong 300 thn ng c L da c di trng (Phng php 2). Sau 2 nm chng pht trin gn nh t nhin vi mt tng gp 3 ln, c ni bao ph n 60%. Vic thu qu gi ca c l Da (140 ht) v c Vch (180 ht) Sng L (vnh Nha Trang) cho vo cc b th nghim, sau 2 4 ngy ht c gii phng.Shttrncgieotrongccbknhckchthc40x80x60 cm, y ph mt lp bn pha ct dy khong 20 cm c t l bn v ct l 1: 3 (bnnhuynbinvctmn).Ncbinclngtrongvchochy trn lin tc qua b t 8 gi sang n 4 gi chiu hng ngy vi kh nng c th thay c khong 200 lt/gi (100% nc trong b/ngy). Dng nh sng tnhin,cchelien,mnggimbtcngnhsngvnhtl bc x nhit. Kt qu sau 10 ngy, ht c Vch ny mm vi t l 98,4% v 97,2% vi c L Da, cc cy mm khi c 15 ngy tui u xut hin r v ctmtnbal.Saubathngmnuiiukinphngthnghim, mt cc cy mm c Vch l 927 cy/m2, c l Da l 708 cy/m2 [1]. Ti Phn vin Hi dng hc ti Hi Phng (nay l Vin Ti nguyn v Mi trng bin), Nguyn Vn Tin v cng s (1998) [7] c nhng nghin cu v cc loi c bin ven b bin Vit Nam v ng a ra c mt bc tranh tng qut v s phn b v thnh phn c bin nc ta, c bit l nghin cu c bin vng bin pha Bc Vit Nam. Nm 2002, Nguyn Vn Tin v cng s th nghim trong vic trng mt s loi c bin mang t min Nam ra trng ti min Bc, v thu c mt s kt qu nht nh. cng l nhng bc khi u cho cc nghin cu v h sinh thi quan trng ny vng bin Vit Nam. Tuy nhin, do cn c nhng hn ch nn mi ch mt s bi bo cng b. V vy, nhng hiu bit y y v c im sinh hc v sinh thi ca c bin Vit Nam, nht l nhng nghin cu v sinh sn phc hi vn cn nhng gii hn nht nh.S ha bi Trung tm Hc liu - HTNhttp://www.lrc-tnu.edu.vn/ 1.3. Khi nim v c im hnh thi ca c bin C bin l nhng thc vt bc cao, c thn, r, l, hoa, qu v phn b ch yu vng bin ven b. C bin bao gm khong 60 loi thuc ngnh Anthophyta, lp Monocotyledoneae, b Hydrocharitales, 2 h Potamogetonaceae v Hydrocharitaceae, chia thnh 12 chi sng hon ton trong mi trng nc bin vi nng mui trung bnh [60]. Cc loi c bin c kh nng chu c tc ng ca sng v thu triu bi kh nng bm chc vo nn y h thng r pht trin v kh nng th phn trong nc. Do c h r pht trin v bm cht trn nn y nn c bin c kh nng nng chu c nhng tc ng ca dng chy v sng bin. V sng vng nc nng ven b nn c bin thch nghi rng vi cc iu kin sinh hc, l ha hc v c vai tr quan trng i vi ngun li cng nh mi trng ven bin. L thc vt mt l mm c hai hnh thc sinh sn: v tnh v hu tnh. Ccqunthcduytrvphttrinchyunhsphttrincachi. cimhnhthicaccloicbincC.DenHartog[15]vC. PhillipsandG.Menez[53]mtvsosnh.Huhtcbinchnhthi ngoi kh ging nhau, bao gm thn b phn t, thn ng, r, chi mang l, hoa v qu ty thuc vo tng thi im sinh trng (hnh 1.1). V cu trc, c bin gm cc phn chnh nh sau: S ha bi Trung tm Hc liu - HTNhttp://www.lrc-tnu.edu.vn/ Hnh 1.1. Hnh thi chung ca c bin Thn:Thn gm c phn thn b (thn ngm) v chi ng (thn ng). Thn thngcdnghnhtrtrnhocdp;chianhnhtheokiuntrchoc khngcquilut.Trnthnbcnhiut,khongcchgiacctl lng (ging). Ty loi m thn b mc ngm di lp bn (ct) y hoc b lan trn mt nn y. T t mc ln mt hay nhiu chi ng, mang cc l. R: R thng mc ra t phn di ca thn b, r ca mi loi u c c im ring (r n, phn nhnh) v mang lng ht. L - phin l: L hnh thnh t m sinh trng cc mu thn; c hnh di di, van haytr trn.Phinlhu htumng, bmtphng, dintch ln,tr c Nn bin (Syringodium isetifolium) c l tr trn, tt c cc loi khc u c ldp.Ngoichcnngquanghp,phinlcnckhnnghpthdinh dng v trao i kh. L c bin cn l ni sng bm ca nhiu loi rong v ng vt khng xng sng. B l: S ha bi Trung tm Hc liu - HTNhttp://www.lrc-tnu.edu.vn/ B l l phn cung l phnh ra m ly chi ng (thn ng) v bc ly nhng l non ang pht trin. B l c dng li nh, mu trng do khng c lc lp nn khng c chc nng quang hp. Hoa, qu v ht: Hoa, qu v ht l c quan sinh sn hu tnh ca c bin. c bin, mt s c hoa c v hoa ci trn cng mt cy (lng tnh), s khc c hoa c v hoa ci ring bit trn mi cy (n tnh). Qu c hnh thnh t s pht trincabusauthtinh(giaophn)vmangcchtbntrong.Htc hnhthnhtsphttrincanon.Hoa,quvhtcamiloityvo iu kin sng m chng c cu trc v hnh dng khc nhau. 1.4. Vai tr ca c bin Cbincvaitrrtquantrngvlmthsinhthibininhnh ca vng bin Nhit i [4] v c nhng vai tr chnh nh sau:Vai tr iu chnh: nhng thm c bin c th lm thay i cc qu trnh sinhthithyvc,ngvaitrquantrngtrongvicnnhvngib, gp phn chng xi lvng b bin. Chng cn l ch th sinh hc v tham gia lm sch nc thi cng nghip v sinh hot. Vai tr cung cp: ni nui trng, khai thc, ni c tr, bi , bi ng ging, ngun thc n ca nhiu loi sinh vt thy sinh. Vaitrsnxut:vtchthuc,ngungen,thcphm,nguynliu cng nghip v nng lng. Vai tr thng tin: nghin cu hc tp, du lch v gii tr. 1.5. Tng quan v iu kin t nhin, mi trng sng ca C bin 1.5.1. Cht y Cc loi c bin khc nhau c th phn bit bi s thch nghi ca chng viccloichty(bng1.1).Zosterajaponicathngxuthinvng triu kn, ca sng hay m ph nc l trn nn y bn st bt v bn nho. Halophila ovalis, H. beccarii v Ruppia maritima ph bin vng triu ven S ha bi Trung tm Hc liu - HTNhttp://www.lrc-tnu.edu.vn/ sng, m nui thy sn vi trm tch bn st v vng c nn y l ct nh. Mt s loi c th sng trn nn , v d loiPhyllospadix spp. c th mc trnnnvngbbinThiBnhDng[29]vmtsloikhcnh PosidoniaoceanicavThalassodendronspp.[35].Ttcnhngloisinh trng trn cn c b r cng cp, chng c th xm nhp v bm chc vo cc k h trn . Tuy nhin, hu ht cc loi c bin u sinh trng trn nn y ct, bn ni b r ca chng rt d dng bm gi vo nn y v to iu kinchohtcnymm.nhngvngcdngchyvsnghotng mnh lm xo trn nn y, gy ra s xi mn lm tn thng c bin. Bng 1.1. Phn b c bin vi c im cht y Loi nn y Dng nn y Loi c bin c trng a im Bn Bn bt nhZostera japonica m Bun (Qung Ninh) Bn st btHalophila ovalisCt B (Hi Phng) Bn Ruppia maritime, Halophila beccarii Xun Lc (Thanh Ha), Kim Trung (Ninh Bnh) Bn ct Bt lnHalodule pinifoliaHn Nm (Qung Bnh) Ct nhHalodule pinifolia Tam Giang Cu Hai, Lng C (Tha Thin Hu), Cn o (B Ra Vng Tu) Bn ctEnhalus acoroides Cam Ranh (Khnh Ha), Ph Quc (Kin Giang) San h - ct Ct san h Cymodocea serrtulata, Cn o (B Ra Vng Tu) S ha bi Trung tm Hc liu - HTNhttp://www.lrc-tnu.edu.vn/ Thalassia hemprichii Ct Syringodium isoetifolium Ph Quc (Kin Giang) (Ngun: Nguyn Vn Tin, 2002, 2004, 2008 [8], [9], [11]) 1.5.2. mui Vit Nam l ni c thnh phn c bin nhit i a dng vi ngng muidaongt5-32(Zosterajaponica,Halodulepinifolia, Halophilaovalis),di25(Halophilabeccarii,Ruppiamaritima)vtrn 25(Enhalusacroides,Thalassiahemprichii,Cymodoceaserrulata,C. rotundata,Thalassodendronciliatum,Haloduleuninervis,Halophila decipiends, H. minor). a s cc loi u sinh trng mui cao. Khi mui h thp v ko di ko theo s tn li ca c bin [8].1.5.3. Nhit Ccloicbinsinhtrngvphttrinvngbinvenbdo chng thch nghi vi ch nhit ca vng ven b min bc nc ta. Nhit nc bin c gi tr cc tiu vo thng 1, cc i vo thng 7 hng nm. Kt qu o ngy 09/01/1997 ti thm c Ruppia maritima nh V (Hi Phng nhit nc t 160C. Cc t kho st c bin ch yu thc hin vo thng 5 v thng 8, nhit nc thay i t 24 340C. C bit ca sng Hn ( Nng)lctriuxung,thmcphibi,nhitnctrongccvngln n 370C [8].1.5.4. c c tc ng mnh n cc hot ng quang hp ca c bin. Chng skhngnhncnnglngtnhsngcnthitchoquanghpnn khng pht trin. Ngoi ra c gia tng c ngha l c nhiu trm tch bn nhuyn bm ln b mt ca l lm gim quang hp [8]. 1.5.5. nh sng S ha bi Trung tm Hc liu - HTNhttp://www.lrc-tnu.edu.vn/ Ssinhtrngvphttrincathcvtnichng,cacbinni ringchuschiphicanhsng,nhntcvaitrquantrngnkh nng quang hp ca c bin. S phn b theo su ca c bin ch yu ph thucvothigianchiusng[20],[25].Cngquanghpcacbin c nh gi thng qua tc gii phng oxy vo mi trng v kh nng quang hp gia cc loi cng khc nhau [48]. Ngoi nhng iu kin sinh thi, mi trng nu trn, cn c pH, cng sng, ch thy triu, cc yu t v sinh v hu sinh khc u nh hng ti s sinh trng v pht trin ca c bin. S phi bi do thy triu vo ban ngy ma h, tri nng v nhit cao lm cht c. y cng l yu t chnh gy ra s bin ng sinh khi ca c vng triu [8]. 1.6. Mt s c im t nhin vng nghin cu Ct Hi bao gm qun o Ct B cch Hi Phng 45 km v pha ng, cch thnh ph H Long 25 km v pha Nam v cch H Ni khong 150 km v pha ng Nam. Pha Bc gip Vnh H Long, tnh Qung Ninh, pha Ty gip o Ct B, huyn Ct Hi, thnh ph Hi Phng, pha ng v Nam l bin ng trong khong ta : v : 2004240 2005245N; 10605411 - 10700705E. Ta trung tm l: 2004742N - 10700038E. Tng din tch t t nhin ca khu d tr sinh quyn qun o Ct B l 26.240 ha, trong din tch mt t 17.040 ha v 9.200 ha mt nc bin. Khu vc Ct Hi c gi ng chim u th t thng 12 n thng 4 nm sau, tc trung bnh t 5,4- 5,9 m/s.Gi ng- Nam v Nam chimu th t thng 5 n thng 8, tc gi trung bnh 5,5 - 6 m/s. Gi Bc v ng - Bc chim u th vo thng 9 n thng 11, tc trung bnh 5,6 - 6,3 m/s. Trongmang,nhitncgimthp,daongtrongkhongt15- 200C. Thng c nhit thp nht trong nm l thng 1 v thng 2, trong cc thng ny, c thi im nhit gim thp di 150C. Trong ma h, nhit nc tng cao, dao ng trong khong t 25 - 320C. Trong cc thng 6 - 8 S ha bi Trung tm Hc liu - HTNhttp://www.lrc-tnu.edu.vn/ nhit cao nht, c th vt 300C. mui ca khu vc ny bin i mnh theohngtbrakhitrongkhnggiankhuvcnghincu,trungbnh dao ng trong khongt 10-32v bin ngrrt theo haimachnh trongnm.Trongccthngmakh,muikhcao,tbinng,dao ng trong khong t 15 32. Ma ma, mui ca nc gim thp hn, dao ng t 10 n 28 [5]. S ha bi Trung tm Hc liu - HTNhttp://www.lrc-tnu.edu.vn/ Chng II - I TNG V PHNG PHP NGHIN CU 2.1. i tng nghin cu i tng nghinculloicXoan(cCnhgin,cngtin)c tn khoa hc l Halophila ovalis (R. Br.) Hooker, 1858 (hnh 2.1). =CauliniaovalisR.Br.,1810;Halophilaovataauct.nonGaud.1858; KerneraovalisSchult.1829;HalophilamadagascariensisSteud.1840; DiplantheraindicaSteud.1840;LemnopsismajorZolingger,1854; Halophilamajor(Zoll.)Miq.1855;HalophilaeuphlebiaMakino,1912; HalophilalinearisdenHartog,1957;HalophilahawaiianaDoty&Stone, 1966; Halophila australis Doty & Stone, 1966. C Xoan c v tr phn loi nh sau [8]: GiiPlanteae Ngnh Anthophyta LpMonocotyledons BHydrocharitales HHydrocharitaceae ChiHalophila LoiHalophila ovalis (R. Br.) Hooker, 1858 Hnh 2.1. Hnh thi c Halophila ovalis (R. Br.) Hooker, 1858 S ha bi Trung tm Hc liu - HTNhttp://www.lrc-tnu.edu.vn/ C XoanHalophila ovalis l mt loi c nhit i c sinh khi thp so vi cc loi c khc [8], nhng li c chu k sinh trng nhanh hn cc loi khc bi kch thc nh b ca chng [22], [62]. Chi Halophila c kh nng tn ti nhng vng lun b tc ng hay ni c nh sng yu v c cao, nhng yu t lm hn ch kh nng pht trin ca c. Halophila c vng phn b rng v gi vai tr tin phong trong kh nng m rng ti nhng vng bin su hncc loikhc(nimccloic khc khngthtn ti)[15]. Chnhmtscimhnhthi,sinhhcvsinhthicacXoanrtc trng nn chng c cc nh khoa hc trn th gii chn lm i tng nghin cu t nhiu nm nay. 2.2. a im v thi gian nghin cuim nghin cu l cc m nui thy sn thuc huyn Ct Hi c ta t 2004811 N 10605314 E. Hnh 2.2. S vng nghin cu Vic thu mu c thc hin thnh 6 t (3 t ma kh v 3 t ma ma)tthng 4 nm2011n thng 8nm2013, vo chn triu,connc ln.ThnghimchohtnymmcthchintiPhngthnghim, PhngSinhthivTinguynThcvtBin(VinTinguynvMi trng Bin) trong nm 2011. 2.3. Ti liu nghin cu S ha bi Trung tm Hc liu - HTNhttp://www.lrc-tnu.edu.vn/ Ti liu phc v lun vn, bao gm: D liu kho st l 54 mu cng cc s liukhc c ghi trong 3 nm (thng4/2011 nthng8/2013)trongccmnuithysnthucthtrn Ct Hi Ct Hi (Hi Phng). Ngoi ra cn tham kho kt qu nghin cu ca cc ti: ticsnm2011:Nghincukhnngtrngbnghtloic Xoan (Halophila ovalis (R. Br.)Hooker, 1858) quy m phng th nghim D n cp Lin hip cc Hi Khoa hc v K thut Vit Nam: iu tra cc loi thc vt thy sinh bin c kh nng hp th CO2 gim hiu ng nh knh, chng bin i kh hu, 2012 - 2013. ti: KC.09.07/11-15: Nghin cu hin trng mi trng, bin ng ngunli,adngsinhhchsinhthivngtriuvenbinminBcVit Nam (t Qung Bnh tr ra), xut m hnh khai thc, nui trng, bo tn vqun l bn vng, 2011 - 2015. 2.4. Phng php nghin cu 2.4.1. Nghin cu thc a 2.4.1.1. Thu mu sinh hc c bin Vic thu mu da vo phng php ca cc tc gi trong v ngoi nc: Phngphpnghincucbin;Surveymanualfortropicalmarine resources;SeagrassResearchMethods;SeagrassNetManualforScientific Monitoring of seagrass habitat [11], [21], [54], [59]. V tr cc trm kho st ti 3 trm thu mu tng ng vi 3 m nui cXoanphnb,cxcnhbngthitbnhvvtinh(GPS).Mu di triu c thu bi thit b ln chuyn dng SCUBA, my quay phim v mynhdinc.Ccmtctvkhungnhlng(0,04m2)ct ngu nhin. Xc nh ph bng khung nh lng (50 cmx 50 cm) c chialm25sauquyvdintch1m2.Tnhdintchbicbinbng thc dy o trc tip kt hp nh vin thm. mui ca nc bin o bng S ha bi Trung tm Hc liu - HTNhttp://www.lrc-tnu.edu.vn/ khc x k cm tay.Nn y cnh gi theo phng php trc quan v phn tch phng th nghim. 2.4.1.2. Thu ht c bin Ht c Xoan c thu bng 2 phng php l trc tip trn cy v lng ng trn nn y [1]. Thu mu trc tip trn cy Qu v ht c thu trc tip t cc chm qu trn thn cy bng cch r cctnc qua sng (0,4 1,0mm).Loib nhnght non, khngt kch thctiuchun(bngkthut tchv ssaikhcvkhi lngring) v quan st di knh lp, phng i 10 ln.Thu mu ht ging c thc hin ti 6 trm bng khung nh lng (20 x 20 cm). S lng ht ging trung bnh cho mi mt vung c tnh bng cng thc: Sd = sd x 25; trong : - Sd l s ht/1 m2 - sd l s ht trn 1 khung nh lng (0,04 m2) Thu mu trong trm tch Phn ln cc ht ging sau khi c gii phng khi thn cy s tri theo dngncvchmtrnnnyxungquanhbic.Htthngphnb khng u trn nn y do tc ng ca dng chy [20], [23], [30], [31]. Vic thu mu ht trong trm tch c tin hnh ti ba im (gia bi c bin) cho mi a im nghin cu.Htgingtrongtrmtchcthuthpbngcchsdngngnha (din tch y khong 0,04 m2). ng nha c cm vung gc trn nn y, su khong 10 cm. Sau khi thu, mu trm tch ny c bo qun trong ti nilon, gimt 250C sau c lc qua sng cmt li (0,5mm) tch ht ra khi trm tch [11]. S ha bi Trung tm Hc liu - HTNhttp://www.lrc-tnu.edu.vn/ S lng ht ging c m trn bng bung m ng vt ph du 10 ml, di knh lp LEICA (sn xut ti Nht Bn), phng i 10 ln. 2.4.2. Nghin cu trong phng th nghim 2.4.2.1. Phng php nh loi Ccmucbin cnhloi bngphngphp hnh thi da trn tiliunhloicbincaNguynVnTinvngnghip(2002),den Hartog C., (1970), Phillips R.C. and Meez E.G. (1988) [8], [15], [53]. Hnh 2.3: Cch o kch thc chi c (a): b l, (b): chiu di l; (c) chiu rng l; (d) chiu di t thn Mu c Xoan sau khi thu, cra sch trong phng th nghim v o kch thc l, kch thc thn lng, m mt chi,... Mu c tch thnh phn trn nn y (chi l v chi hoa) v phn ngm (thn, r) sau c sy kh bng t sy (hng: MEMMERT, k kiu: ULE 400), 64oC trong 24 gi.Xcnh trnglng bngcnintsais0,1g(hng:EXCELL,k kiu: KP) 2.4.2.2. m ht c bin Ht c m trn a Petri, ng knh 10cm, y l bn-ct (ly ngay ti im thu ht) v nc bin (ly ti ni thu ht), pha long (bng nc thu ti ca sng v nc t) cho cc mui l 0 (bng nc ct), 5, 10, 15,20,25v30xcnhgiihnnymmtheomui.S S ha bi Trung tm Hc liu - HTNhttp://www.lrc-tnu.edu.vn/ dng phn bn thng mi v hormon thc vt [12] nhm kch thch s ny mm ng u. Nhit (250C) v cng nh sng (95 112 lux) khi m httngngmitrngtnhindinnyngoimnuivcc nghin cu cho thy rng ht ging Halophila ny mm d dng khi tip xc vi nh sng [46].Mi l th nghim gm 3 a, mi a m 10 ht v th nghim c lp li 3 ln (hnh 2.4). Hnh 2.4. B tr th nghim m ht Kim tra s ny mm ca ht sau 5, 10 v 20 ngy. Hin tng ny mm ca ht ging xy ra, khi trng thi ng b ph v (du hiu ca khe nt trn ht v xut hin ca trc l mm [12]. Sau khi xc nh c mui thch hp cho ht nymm,s ht cn liscemmhtvchncygingchovictrngcbinmi trng c mui thch hp ny. 2.4.2.3. Trng c bin Saukhicchtnymm,ccmmcchuynvoccbth nghim c kch thc 40 cm x 60 cm x 40 cm (rng x di x cao). Mc nc trong b th nghiml 10 cm, 20 cm v 30 cm nhm theo di nh hng ca mc nc ti s pht trin ca c bin.Mttrngl48htmmtrongmtb(200htmm/m2),khong cchgiacchtmml5cm.Chtyvnctrongccbthnghim c ly t ni c c Xoan ang pht trin tt nht ngoi t nhin. mui S ha bi Trung tm Hc liu - HTNhttp://www.lrc-tnu.edu.vn/ c nh 15 v nc trong b c lu thng tun hon bng my sc kh. Thay nc nh k 3 ngy/ln. Cc b th nghim c t trong phng th nghim, cng nh sng nhn to gi n nh t 13.000 15.000 lux (tng ng vi cng nh sng chiu ln mt bi c bin ngoi t nhin), ch chiu sng 12 gi sng 12 gi ti. Th nghim c thc hin lp li 3 ln. 2.4.2.4. Phn tch trm tch Phng php phn tch thnh phn ht: trm tch sau khi c loi bmuivvtchthuccphntchbngrychotrmtchlnhn 0,063mm v s dng pipt phn tch cc cp ht nh hn 0,063 mm, phn loi trm tch theo Lisitzin A.P, 1986 [37]. 2.4.2.5. Quan trc mt s yu t mi trng Thng s nhit , nh sng o lin tc hng ny i in cho ma ma vmakhtthng2nthng10nm2012bngmycmbintng HOBO Pendant Temp/Light, 64k. mui o bng my khc x k Ti-SAT 100A. 2.4.2.6. X l s liu nhhngcasthayimitrngtheomatcngnsinh trng, sinh khi v sinh sn ca c bin ckim trabi phn tch thng k (ANOVA). Mi tng quan gia t l sinh khi trn mt t v sinh khi di mt t vi mt chi c kim tra bi phng trnh hi quy tuyn tnh: y = ax + b trong : y l sinh khi trn mt t; x l mt chi S ha bi Trung tm Hc liu - HTNhttp://www.lrc-tnu.edu.vn/ Chng III - KT QU NGHIN CU V THO LUN 3.1. c im hnh thi ca loi c Xoan trong m nui thy sn Tytheotngiukincth,hnhthingoicacXoancnhiu thayicho ph hp.LoicXoancs dngnghin cucho lunvn ny c thu trong m nui, c nhng c im c th nh sau:3.1.1. Thn Thn gm c phn thn ngm v thn ng, b di nn y hoc b lan trnmtnny,phnngnvnlngingnhcyduty.Thntho, dn, c dng hnh tr, ng knh trung bnh 1,3 0,1 mm, di n 100 mm. Trn thn c nhiu mu t ni mc ln cc phn nhnh, gia cc mu t l lngthn di trung bnh t 26,7 1,3mm(hnh3.1).Phn nhnh n trc mt bn v thng ch n bc 3. Hnh 3.1. Hnh thi chung ca thn c Xoan v lt ct ngang thn 3.1.2. R R ca c Xoan ch c mt, khng phn nhnh, mc t cc mu t thn phn di thn b, trn r c nhiu lng ht. ng knh trung bnh ca r l 0,5 0,1 mm (hnh 3.2). S ha bi Trung tm Hc liu - HTNhttp://www.lrc-tnu.edu.vn/ Hnh 3.2. Hnh thi r 3.1.3. L, phin l CXoancphin lhnh oval di13,90,4mm,rng8,00,3mm. Mp l nguyn vn, chp t, gc l nhn. Cung l di t 23,7 1,0 mm. Gn hnhlngchimgmcmtgnchnhv913ignphhaibnsong song, i xng hoc so le nhau, i ln to gc 45 600. Tn cng cc gn ph tkhiphnnhnhnilinvignmpl,gnmplchyxungquanhv cch mp l trung bnh l 0,3 mm. S lng gn ph l c im quan trng phn bit vi cc loi cng chi Halophila (hnh 3.3). Hnh 3.3. Hnh thi l. a. hnh thi phin l.b. u l v cc gn nhum thuc tm. c. u l v cc gn vi mu tht. 3.1.4. Vy l Vy l ca c Xoan l2 vymng, trong sut, khngc cung, nmmi gc cung l, mt vy bao ly chi non v hoa sau ny, mt vy bao ly thn b (hnh 3.4). Vy l tn ti cng vi s pht trin ca l v hoa qu. S ha bi Trung tm Hc liu - HTNhttp://www.lrc-tnu.edu.vn/ Hnh 3.4. Hnh thi vy l 3.1.5. Hoa HoacXoanllointnhkhcgc(ntnhbitchu).Hoa c c unhn,bacnhhoahnhchnht, di6 - 8 mm; baophnthundi. Hoa ci cng c bc b hoa, trong sut, xp lp ln nhau nh mi ngi, di 5 -7 mm; non sokhngcung hoccung ngn, di 1 - 2 mm, ng knh 0,5 - 1mm; hoa di1 - 6 mm, chianh phatrn thnh 3 si vi,di 6 -20 mm (hnh 3.5). Hnh 3.5. Hnh thi hoa 3.1.6. Qu v ht Qu cXoanchnhcuhochnhtrng.muxanhnhtnvng nht, ng knh 2,5 - 3 mm; cc ht c ph bi v dng li, c 5 13 ht hnh cu mu trng hoc vng nu, vi ng knh htt 0,3 0,5 mm (hnh 3.6). Theo m t ca den Hartog (1970) [15] th s lng ht c Xoan ln n S ha bi Trung tm Hc liu - HTNhttp://www.lrc-tnu.edu.vn/ 30ht/qu,nhiuhn23lnsovinghincuny.CntheoKuoand Kirkman, (1992) [34] l 16 ht v trung bnh l 7 ht trn mi qu. Hnh 3.6. Hnh thi qu v ht c Xoan. a. qu non trn thn;b. qu trng thnh; c. tch qu v ht. Nhn chung, kch thc ca c Xoan cc m nui ti Ct Hi rt nh. di trung bnh l c Xoan theo m t ca N. V. Tin v cng s (2002) [8] cao gp 2 ln (27,1 mm) so vi kt qu ca nghin cu ny. Theo nghin cu caDuarte(1999b,1999)[19],[20]vkchthccbinthucchi Halophila cho thy rng cc loi thuc chi ny u c kch thc nh, khong 1,1-1,3mm.Tuynhin,chiudilngthncXoancanghincuny (26,7 mm) li cao hn ( 12 - 17 mm) (bng 3.1). Bng 3.1. Mt s so snh v kch thc thn c Xoan NgunChiu di l c (mm) ng knh thn (mm) Chiu di l lng (mm) Nghin cu ny13,91,326,7 Duarte, 1991b [19]-1,317 Duarte, 1999 [20]-1,112 13 N.V. Tin v cs, 2002 [8] 27,1-- 3.2. Mt s c im sinh thi ca loi c Xoan 3.2.1. Mt s thng s mi trng trong m nui 3.2.1.1. Nhit nc S ha bi Trung tm Hc liu - HTNhttp://www.lrc-tnu.edu.vn/ Kt qu o lin tc t ngy 10/02/2012 n ngy 15/10/2012 ti thm c m nui c nhit nc t trung bnh 280C, thp nht vo thng 2 vi 180C, nhit nc tng dn v t mc cao nht vo thng 5 vi 320C. Khi nhittmccaonhtcnglthiimrahoa,qucacXoan(hnh 3.7). 05101520253035T2 T4 T6 T8 T10Nhit ( C) v mui (S)05000100001500020000250003000035000C-ng nh sng (Lux)Nhit ( C)Nng mui (S)Cng nh sng (Lux) Hnh 3.7. Din bin ca mt s thng s mi trng. 3.2.1.2. Cng nh sng Dliuv cng nhsngthucng thi vikt qu nhit nc. Cng nh sng trung bnh t 14.200 lux. Cao nht vo thng 2 vi 32.067 lux v thp nht vo thng 9, thng 10 vi 3.170 lux (hnh 3.7). Ma ma pha Bc Vit Nam bt u vo thng 5 n thng 9. Lng ma thay i hng thng, trong ma malng ma t gi tr rt cao khin c tng nhanh, ng thi nhit tng to iu kin thun li cho cc loi to lam pht trin th hin s suy gim cng nh sng.3.2.1.3. Nng mui Ti liu v nng mui c quan trc nh k t thng 2 n thng 10 nm 2012 cho thy gi tr trung bnh l 24,5, cao nht vo ma kh vi 32,8 thng 3, gim dn vo ma ma vi 18,5 v thp nht l S ha bi Trung tm Hc liu - HTNhttp://www.lrc-tnu.edu.vn/ 15,3 vo thng 6 (hnh 3.7). Nh vy, ng thi vi hin tng c ho v gim nhit nc l hin tng ngt ho vng nc trong m nui gy ra nhng bin i ln ca mt s nhn t mi trng. Cng vi hin tng gim nh sng v mui th nhit khng kh cng thay i r rt trong ma ma. iu ny nh hng n nhit nc bin. 3.2.1.4. Nn y Nnylmttrongnhngyutquantrngtrongisngcacc loicbin.Tuyvymiloicbinaphttrintrnloinnykhc nhau.Vd,cRuppiamaritimathngmctrnnnylbn,c Thalassia hemprichii a mc trn ct v c XoanHalophila ovalis thng phttrin trn bnct, bnst bt[1],[8].Tuyvy,quathng s phntch cp htchtyt6trmti khu vc nghincuchothycXoanckh nngphttrinnhngloihnhchtykhphongph.Tloinny bn bt nh n ct nh v ct trung (bng 3.2). Bng 3.2. Kt qu phn tch cht y K hiu mu Thng s trm tch Loi trm tch Md (mm)Sk CH10,0340,502Bn bt nh CH20,3011,094Ct trung CH30,1411,157Ct nh CH40,0380,411Bn bt nh CH50,2410,712Ct nh CH60,0450,308Bn bt trung (Ngun: Phng a mi trng phn tch; Md ng knh ht; Sk lch, nu ln hn 1 th phn ln cc cp ht nghing v pha ht th, nu nh hn 1 th tp hp cc cp ht nghing v cc cp ht mn) Qua bng s liu trn cho thy c nhiu la chn cht y phc v cho th nghim kh nng ny mm ca ht c Xoan, tuy nhin phi m bo cht S ha bi Trung tm Hc liu - HTNhttp://www.lrc-tnu.edu.vn/ y l t bn bt nh vi ng knh ht (Md) l 0,034 mm n ct trung vi Md l 0,301 mm. 3.2.2. S bin ng theo ma ca c bin trong m nui 3.2.2.1. Phn b v din tch + Phn b rng C Xoan phn b u ht cc m nui qung canh, nhng m nui t c s can thip ca con ngi, cc m h tr nc v ven cc con mng xung quanh m. Qua o c v thng k ton vng v din tch phn b ca Cxoanlnti50havomakhvcnli35havomama.Chim 30% tng din tch mt nc, trong gm c cc m nui ang canh tc v b hoang (hnh 3.8). Hnh 3.8. Phn b ca c Xoan + Phn b su S phn b theo su ca c bin ti cc m nui huyn Ct Hi kh phong ph. Chng phn b v pht trin t vng ven m vi mc nc S ha bi Trung tm Hc liu - HTNhttp://www.lrc-tnu.edu.vn/ nhng khi l bi 0 m n su tm m l 1,5 m. Tuy vy, ph v sinh lng cao nht ca c Xoan thu c trong m nui thng l nhng thm c phn b su 0,5 m. 3.2.2.2. Bin ng cc ch tiu sinh lng Qua phn tch thc a v phn tch phng th nghim, thu c mt s ch tiu sinh lng v th hin nh sau (bng 3.3): Bng 3.3. Cc thng s in hnh v sinh lng c Xoan Ch tiu Ma (thng, nm) Ma khMa ma 4/20112/20123/20137/20115/20128/2013 SL (mm2)88,672,883,3104,084,9121,1 Trung bnh81,6103,3 ph (%)878097656355 Trung bnh8861 Csh (chi/m2) 4923 672 4406 780 5327 750 2452 141 2200 98 2259 137 Trung bnh4885 4022303 69 Ww (g ti/m2) 386,1 17,5 343,6 13,9 354,1 13,4 257,7 31,1 294,1 20,8 255,1 22,6 Trung bnh361,3 7,8269,0 15,2 (skt/skd)*1,051,361,290,720,40,47 Trung bnh1,230,53 FL 478 12 504 11 395 15 56 511 20 Trung bnh459 1622 4 Vi: (*) T l sinh khi trn mt t v sinh khi di mt t; (SL) din tch phin l; (Csh ) mt chi; (Ww) tng sinh khi ti; (FL) Mt hoa R rng, cc gi tr ph, mt chi v tng sinh lng rt cao vo ma kh khi cng nh sng chiu ti nn y cao v lng ma thp gip cho mui n nh ngng thch hp i vi c Xoan, nhng li rt thp vo ma ma khi lng ma v nh sng chiu ti y gim. S ha bi Trung tm Hc liu - HTNhttp://www.lrc-tnu.edu.vn/ Ma kh khi m s lng chi c ln nht th sinh khi c bin cng t gi tr cao nht nhng din tch phin l th khng phi l ln nht. Sinh khi trn mt t c xu hng tng ln cng vi s lng chi tng. Mt chi c cc m nui Ct Hi rt ln do din tch phin l nh. Cc phin l c c th ph chng nn nhau to nn nhiu lp l trn mt n v din tch. Chnhiunynhhngnsinhkhitrnmttcalc.iuny ng vi nhng quan st v mi tng quan cht ch gia mt chi v sinh khi ca c cc vng bin khc nh: Bolinao, Philippines [55] v vng m ph Venice, Italy [57].+ ph v din tch phin l phvdintchphinlcacccXoantrongmnuics thayitheomarrt.Vidintchphinlvomakhl81,6mm2, ma ma l 103,3 mm2, tng 26,7%. Tuy nhin, vi ph kh cao vo ma khl88%vmamal61%,gim30,7%vphgia2ma(bng 3.3). Khi phn tch v so snh s bin ng ca hai yu t nu trn gia hai malintctrong3nmchothyrng,trongmakhkhiphtngth din tch phin l gim v ngc li, vo ma ma khi ph gim th din tch phin l tng (hnh 3.8).S ha bi Trung tm Hc liu - HTNhttp://www.lrc-tnu.edu.vn/ 0204060801001201402011 2012 2013 2011 2012 2013Ma kh Ma m-a ph (%)Din tch phin l (mm2) Hnh 3.8.Biu din bin gia ph v din tch phin l + Mt chi v sinh khi Mt chi trung bnh trong 3 nm vo ma kh l 4885 402 chi/m2 v vo ma ma l 2303 69 chi/m2 (bng 3.3), gim 52% v cho thy rng c s bin ng kh cao v mt chi gia cc ma trong nm. Tngsinhkhitrungbnhtrong3nmvomakhl361,37,8g ti/m2vvomamal269,015,2gti/m2,gim25%vtngsinh khi gia hai ma trong nm (bng 3.3). Khi phn tch mi quan h gia hai ch tiu trn cho thy chng c s tngquantuyntnhvktquchorahmtngquany=0,0344x+ 191,38 vi h s r = 0,91 (hnh 3.9). iu th hin mi tng quan rt cao gia mt chi v tng sinh lng ca c Xoan trong m nui. S ha bi Trung tm Hc liu - HTNhttp://www.lrc-tnu.edu.vn/ Hnh 3.9. Mi tng quan gia mt chi v sinh lng c Xoan + T l sinh khi trn v sinh khi di T l sinh khi trn v di mt t ca c Xoan cng cho thy s sai khc gia hai ma trong nm. T l sinh khi trn v di mt t cho thy rng ma kh c pht trin tt hn ma ma, vo ma kh t l trung bnh l 1,23 (tc l c 1 kg thn r th c 1,23 kg thn chi, l v chi hoa), vo ma ma t l trn cn li l 0,53 (1 kg thn r th ch c 0,52 kg thn chi, l v chi hoa) (hnh 3.10). Qua y, phn no gii thch kh nng tn ti ca cc loicbinnichungkhichngchthngthnngmvrbmgivo nny,gipchngcthtntiquanhngthiimkhngthunliv iu kin t nhin. S ha bi Trung tm Hc liu - HTNhttp://www.lrc-tnu.edu.vn/ 00,20,40,60,811,21,41,62011 2012 2013 2011 2012 2013Ma kh Ma m-aT l sinh khi trn v sinh khi d-i (skt/skd) Hnh 3.10.Bin ng t l sinh khi trn v sinh khi di S dng hm tng quan tuyn tnh phn tch mi gia t l sinh khi trn mt t v sinh khi di mt t vi mt chi c Xoan, kt qu thu chmy=0,0002x+0,3152vihsr=0,86vktlunlchngc mi tng quan rt cht ch (hnh 3.11). Hnh 3.11. Mi tng quan gia t l skt/skd mt t vi mt chi Kt qu trn kh ph hp vi c im sinh thi ni chung ca c bin vng nhit i, ngha l c bin thng pht trin tt vo ma kh khi lng mathp, muicao vn nh, thockhng cbovsng ln.ng S ha bi Trung tm Hc liu - HTNhttp://www.lrc-tnu.edu.vn/ thi,cbincngthngbtilivomamadoccao,mui gim v khng n nh. Kt qu ny cng ging vi kt qu khi nghin cu loicXoanTamGiangCuHai(ThaThinHu)vtiliuca Terrados et al (1998) [61] khi nghin cu c bin Philipin [8], [10]. So snh c Xoan trong m nui ti huyn Ct Hi vi nghin cu ca Ertemejervcngs(1999)[22]chothymtchicacXoantrong nghin cu ny cao hn. Din tch phin l c Xoan m Ertemejer nghin cu lnhngp2lnsovinghincuny.Tuynhin,tlsinhkhitrnv sinhkhidinghincunycphnlnhn(bng3).iucng chng t ti sao ph trung bnh cao ca c Xoan c Xoan Ct Hi (xp x 75%). RtcthvisphttrincacXoantrongiukinsinhthib hptrongmtkhongkhnggiangiihnlccm,bbaoquanhkhin cho chng mun tng trng v mt v ph th phi thu gim v kch thc. Ni cch khc, l s thay i kiu hnh thch nghi vi iu kin sng. 3.2.3. Ma ra hoa ca c Xoan Hoa ca c Xoan xut hin vo khong thng 2 n thng 4 hng nm, i khi qu cn xut hin ko di n thng 7. Nh vy hoa ca Xoan ch yu ch xut hin vo ma kh, khi m mui v cng nh sng chiu ti y cn cao v n nh. C Xoan c s lng hoa trung bnh l 459 16 chi hoa/m2, trung bnh c c 10 chi c th c 1 chi hoa (hnh 3.12).em kt qu trn so snh vi Nguyn Vn Tin v ng nghip (2002) thy rng ma ra hoa v qu ca c Xoan ti cc m nui huyn Ct Hi c thi gian di hn t thng 2 n thng 7 so vi t thng 3 n thng 5 [8]. S ha bi Trung tm Hc liu - HTNhttp://www.lrc-tnu.edu.vn/ 01002003004005006002011 2012 2013 2011 2012 2013Ma kh Ma m-aS l-ng chi hoa (chi hoa/m2) Hnh 3.12. Bin ng s lng chi hoa 3.3. Kh nng ny mm ca ht c Xoan 3.3.1 Kt qu thu ht3.3.1.1. Thu trc tip trn cy S ht thu trc tip ti Ct Hi dao ng t 1750- 2175 ht/m2, trung bnh l 1925 128 ht/m2. Tng s ht c thu c bng phng php thu ht trc tip l 375 ht (bng 3.4).Bng 3.4. Kt qu thu ht trc tip Thng s Trm D1D2D3D4D5D6 S ht/0,04 m2 745487704149 S ht/m2 185013502175175010251225 Trung bnh 1562 177ht/m2 3.3.1.2. Thu trong trm tch S ht thu trong trm tch ti Ct Hi dao ng t 1225- 1375 ht/m2, trung bnh l 1316 ht/m2. Tng s ht c thu c bng phng php thu ht trong trm tch l 220 ht (bng 3.5). Bng 3.5. Kt qu thu ht trong trm tch S ha bi Trung tm Hc liu - HTNhttp://www.lrc-tnu.edu.vn/ Thng s Trm D1D2D3D4D5D6 S ht/0,04 m2 491955232054 S ht/m2 122547513755755001350 Trung bnh 916 180 ht/m2 T bng 3.4 v bng 3.5 c th thy rng, phng php thu ht trc tip chohiuquhn.Tngshtgingthucsauhaiphngphpl595 ht. SlnghtcXoantngngviktluncaktqu HammerstromvKenworthy(2003)[28]mts lng ht thu cbi c Halophila decipiens vnh Mexico t 130 n 3.400 ht m2. Nhng thp hnrtnhiusovinghincuMcMillanvSoong1989Panamavi 13.500 ht m2 [47]. Hay 70.000 ht/m2 c ghi nhn t quan st thc a ca Kuo v cng s, (1993) [34] loi Halophila tricostata, v cng loi Halophila decipiens l 176.880 ht/m2. Nhng iu nu trn ngoi yu t v kh hu v sinh thi vng min m cn ph thuc rt ln vo k thut, phng php thu ht p dng. 3.3.2. Kt qu m ht Sau4n5ngy,htntv.ccmui5,10,15,20, 25, sau 9 n 10 ngy r mm bt u ln lt xut hin (theo mn tng dn). mui 30, sau 12 ngy r mm mi xut hin. Sau khi xut hin l mm, tt c cc l u hng ln pha trn (tnh hng sng). Sau 20 ngy thnghim,tlnymmcahtcbincssaikhcrtln,daong trong khong 0% ( mui 0,) ti 80% ( mui 15) v trung bnh t 41,9% (hnh 3.13). S ha bi Trung tm Hc liu - HTNhttp://www.lrc-tnu.edu.vn/ 0%63,30%56,60%80,00%46,60%30%16,60%0%10%20%30%40%50%60%70%80%90%0 5 10 15 20 25 30 muiT l ny mm Hnh 3.13. Biu t l ny mm cc mui Nh vy, mui 15, t l ny mm ca ht c Xoan t gi tr cao nht (80%). Kt qu ny hon ton ph hp vi nghin cu ca Orth v cng s(2000),khiphthintlhtgingcbinnymmtcaonht mui 15 [43]. y l c s cho vic la chn mi trng c mui thch hp thit k th nghim gieo trng. Sauccthnghimtrnvmnymmshtcnlimui thch hp 15. Kt qu, tng s ht ny mm thu c 491 ht ny mm.3.3.3. Kt qu gieo trng 3.3.3.1. Hnh thi V hnh thi, sau 2 n 3 ngy, lp v bn ngoi ht c loi b t vt nt ca ht. Cc r nh pht trin t ca tr di l mm, v c pht trin ca ti l mm. L tht u tin, vi duy nht mt gn n, ni ln t ti l mm. giai on ny, si lng di n bo thng pht trin t b mt ca tr di l mm.L th hai xut hin tip t mng bc ca l trc, v mt gc bn pht trin ti ca l u tin trn ti l mm (hnh 3.14). S ha bi Trung tm Hc liu - HTNhttp://www.lrc-tnu.edu.vn/ Hnh 3.14. Giai on pht trin khc nhau ca ht mm. a. giai on mt l mm vi (C) l mm, (CP) ti l mm v (H) tr di l mm. b. giai on hai l mm vi (R) r v (SH) cc lng ht 3.3.3.2. T l sng Sau 12 ngy gieo ht ( ny mm), cc ht mm pht trin thnh cy ging cc giai on khc nhau vi t l sng gia 3 l th nghim mc nc 10 cm v 20 cm l 67%, mc nc 30 cm l 56%. T l sng trung bnh cc mc nc l 63% (bng 6). Nhvy,ccsukhcnhau,tlsngcahtcbin(saukhi ny mm) c s sai khc khng ln (t 56% n 67%).Sau 15 ngy, t l sng dao ng trong khong 4% (30 cm) n 8% (20 cm) v trung bnh l 6%. Sau 20 ngy, ti cc su th nghim 10 cm v 20 cmcbinchtht,chcnlitlsngrtnh(1%)su30cmv trung bnh t 0,5% (bng 3.6). Bng 3.6. T l sng ca ht mm cc giai on S ngy th nghim L th nghim T l sng cc mc nc (%) 10 cm20 cm30 cm 12 ngy L 1466065 L 2776954 L 3797150 S ha bi Trung tm Hc liu - HTNhttp://www.lrc-tnu.edu.vn/ Trung bnh*676756 15 ngy L 14102 L 2866 L 3884 Trung bnh* 784 20 ngy L 1000 L 2002 L 3002 Trung bnh* 001 * T l c lm trn s Kt qu trn tng ng vi kt qu nghin cu ca J. Kuo v cng s (1993) khi th nghim loi Halophila tricostata cng nhn thy c ch t c n giai on 3 l mm. Theo cc tc gi trn, trong iu kin phng th nghim bnh thng, vic m ht v trng c bin trong giai on u tng i d nhng sau giai on c c 3 l th l vic rt kh (cha r nguyn nhn) [33]. S ha bi Trung tm Hc liu - HTNhttp://www.lrc-tnu.edu.vn/ Phn 4. KT LUN V NGH 4.1. Kt lun *CXoanHalophilaovalistrongccmnuithysnhuynCtHic kchthcnhsovicXoanccsinhcnhkhc,vingknhthn trung bnh 1,3 0,1 mm, chiu di lng 26,7 1,3 mm, l di 13,9 0,4 mm, rng 8,0 0,3 mm vi 9 13 i gn ph hai bn.Ma ra hoa ca c Xoan l vo cui Xun, c khi ko di ti thng 7.* Sinh khi ti trung bnh nm l 315 g ti/m2, ph trung bnh l 78%, mt chi trung bnh 3594 chi/m2 v tng din tch phn b trn 50 ha vo ma kh v cn li 35 ha vo ma ma. Sinh khi, ph, phn b v mt chi ca c Xoan thay i theo ma, gim mnh trong ma ma (thng 5 n thng8)khilngnclnmangtheolngphsacao,khinmui gim, hn ch nh sng chiu ti nn y. * Sau 4 n 5 ngy, ht ny mm. T l ht ny mm cao nht khi m mui 15, t 80%. Giai on gieo trng, t l sng trung bnh ca c Xoan sau 12 ngy l 63%, sau 15 ngy l 6% v sau 20 ngy l 0,5%. Hu ht c khng sng c qua giai on c ba l. 4.2. ngh * Cn c cc nghin cu lp li nhiu ln c nhng so snh v phng php v kt qu nghin cu, c bit l sinh trng, sinh sn v phn b.* gii quytnhng vncntnti nghchotip tc thc hincc nidungclinquannvicsinhsnbnghtcacbin(Khnggian phn b v thi gian bo qun ht t nhin trong trm tch, mi quan h gia thnhphnloivhtgingtibicaloi,nguynnhnckhngsng c qua giai on 3 l mm trong iu kin th nghim) S ha bi Trung tm Hc liu - HTNhttp://www.lrc-tnu.edu.vn/ DANH MC CC CNG TRNH KHOA HC STTTN CNG TRNH 1 Cao Vn Lng, 2011. Hin trng thm c bin m ph Tam Giang CuHai(ThaThinHu).TuyntpbocoHinghKhoa hcbintonquclnthV.NhxutbnKhoahcTnhinv Cng ngh, Q.4, tr.312 318. 2 Nguyn Th Thu, Cao Vn Lng, Trn Mnh H, inh Vn Nhn, 2011. nh gi mc suy thoi cc thm c bin ven b Vit Nam. Tuyn tp bo co Hi nghi Khoa hc bin ton quc ln th V. Nh xut bn Khoa hc T nhin v Cng ngh, Q.4, tr.295-301. 3 CaoVnLng,2011.HintrngccthmcbinCai(Hi AnQungNam).TuyntpTinguynvMitrngbin.Nh xut bn Khoa hc T nhin v Cng ngh, tp XVI, tr.144-150. 4 Cao Van Luong, Nguyen Van Thao, Teruhisa Komatsu, Nguyen Dac VeandDamDucTien,2012.Statusandthreatsonseagrassbeds usingGISinVietnam.Proc.SPIE B525,RemoteSensingofthe Marine Environment II, pp.852512. 5 Cao Vn Lng, m c Tin, V Mnh Hng, 2013. Nghin cu khnngtrngbnghtloicXoan(Halophilaovalis(R.Br) Hooker, 1958) quy m phng th nghim. Bo co Khoa hc v Sinh thivTinguynsinhvt,HinghKhoahctonQuclnth Nm. Nh Xut bn Nng nghip, tr.1458 1462. S ha bi Trung tm Hc liu - HTNhttp://www.lrc-tnu.edu.vn/ TI LIU THAM KHO 1.NguynHui,PhmHuTr,NguynThLnh,NguynXunV, 2006. Chng VIII. Cc gii php bo v v phc hi h sinh thi c bin. TmttBoco ti:Nghincu gii phpbov,phc hicch sinhthirnsanh,cbinvkhcphcnhimmitrngbint sinh. Tuyn tp cc kt qu ch yu ca chng trnh iu tra c bn v nghin cu ng dng cng ngh Bin. Quyn II. M s KC.09.07. 2.NguynXunHa,NguynHui,PhmHuTr,NguynThLnh, 1999. Cc thm c bin pha nam Vit Nam. Tuyn tp Bo co Khoa hc, Hi ngh Khoa hc Cng ngh Bin ton quc lnth IV, tp II. Nh xut bn Thng k, tr.967-974. 3.NguynXunHa,NguynHui,PhmHuTr,NguynThLnh, 2000. Nghin cu s bin ng cc thm c bin Enhalus acoroides (L.f.) Royle,Thalassiahemprichii(Ehrenb.)Asch.,Cymodoceaserrulata (R.Brown) Asch. And Magn. vng bin ven b tnh Khnh Ha. Tuyn tp Bo co Khoa hc Hi ngh Khoa hc Bin ng 2000, tr.179-180. 4.TThLanHng,2005.SeagrassNet:mtsktqugimstcbin o Th Vng, tnh Qung Ninh. Tp ch Ti nguyn v Mi trng Bin. Nh xut bn Khoa hc v K thut. Tp IX, tr.189-195 5.TrnnhLn,NguynVnTho,NguynT.T.H(2010).nhgi hin trng mi trng v xc nh cc vn u tin phc v qun l tng hpvngbbinHiPhng.BocoTnghpticpthnhphHi Phng. M s: T.MT.2008.498. 6.Nguyn Th Thu, Cao Vn Lng, Trn Mnh H, inh Vn Nhn v nnk, 2011.nhgimcsuythoiccthmcbinvenbVitNam. TuyntpbocoHinghKhoahcBinTonquclnthV-2011, tr.295-301 S ha bi Trung tm Hc liu - HTNhttp://www.lrc-tnu.edu.vn/ 7.Tien N.V., Thung D. C., Thanh L.T., 1998.Composition and distribution of seagrass in Quang Ninh, Viet Nam. Resources and Marine Environment 5, tr.36-42. 8.Nguyn Vn Tin, ng Ngc Thanh v Nguyn Hu i, 2002. C bin VitNam;Thnhphnloi,phnb,sinhthisinhhc.Nhxutbn Khoa hc v K thut, H Ni. 164tr. 9.Nguyn Vn Tin (Ch bin), 2004.Tin ti qun l h sinh thi c bin Vit Nam (Approaches to management of seagrass ecosystem in Vietnam). Nh xut bn Khoa hc v K thut; 132tr. 10. NguynVnTin,ChuThCng,TThLanHng,2006.nhgi ngun li c bin vng ven bin Trung b, Ty Nam b v xut cc gii php s dng bn vng ngun li. Bo co tng kt ti lu gi ti Vin Ti nguyn v Mi trng Bin, 182tr. 11. Nguyn Vn Tin v T Th Lan Hng, 2008.Phng php nghin cu C bin (Seagrass research methods). Hi Phng, 103tr. 12.Bewley, JD, M Black. 1994. Seeds: Physiology of Development and Germination. Plenum Press, New York, pp.303-311. 13. CatharinaJ.M.Philippart,1995.Effectsofshadingongrowth,biomass andpopulationmaintenanceoftheintertidalseagrassZosteranoltii Hornem.intheDutchWaddenSea.JournalofExperimentalMarine Biology and Ecology Volume 188, Issue 2, 26 May 1995, pp.199-213. 14. Davis,R.C.,andShort,F.T.,(1997).Restoringeelgrass,Zosteramarina L.,habitatusinganewtransplantingtechnique:Thehorizontalrhizome method. Aquatic Botany, 59: pp.12. 15. Den Hartog C., 1970. The seagrass of the world, North Holland. Publ. Co., Amsterdam, 265p.16. Duarte C.M., Marb N., Agawin N., Cebrin J., Enrquez S., Fortes M.D., Gallegos M.E., Merino M., Olesen B., Sand-Jensen K., Uri J., Vermaat J., S ha bi Trung tm Hc liu - HTNhttp://www.lrc-tnu.edu.vn/ 1994.Recontructionofseagrassdynamic:agedeterminationsand associatedtoolsfortheseagrassecologist.Mar.Eco.Prog.Ser.107, pp.195-209. 17. DuarteC.M.,MerinoM.,AgawinN.S.R.,UriJ.,FortesM.D.,Gallegos M.E.,MarbN.,HemmingaM.A.,1998.Rootproductionandbelow-ground seagrass biomass. Mar. Eco. Prog. Ser. 171, pp.97-108. 18. Duarte C.M., 1991a. Seagrass depth limits. Aquat. Bot. 40, pp.363-377. 19. Duarte C.M.,1991b. Allometric scaling of seagrass form and productivity. Mar. Ecol. Prog. Ser. 77, pp.289-300. 20. Duarte C.M. and Chiscano C.L., 1999. Seagrass biomass and production: a reassessment. Aquat. Bot. 65, pp.159-174. 21. English, S., C. Wilkinson and V. Baker, 1997. Survey Manual for Tropical MarineResources.2nded,ASEAN-AustraliaMarineScienceProject: LivingCoastalResources,AustralianInstituteofMarineScience,PMB No. 3, Townsville Mail Centre, Australia 4810, 390p. 22. ErtemejerP.L.AandStapelJ.,1999.Primaryproductionofdeep-water Halophila ovalismeadows. Aquat. Bot. 65, pp.71-82. 23. Fenner,M.,1995.Ecologyofseed-banks.In:Kigel,J.,Galili,G.(Eds.), Seed Development and Germination. Marcel Dekker, New York, pp.507528. 24. FortesM.D.,1988.MangroveandsegrassbedsofEastAsia;habitat under stress. Ambio 17, pp.207-213. 25. Fortes,M.D.1995.SeagrassesofEastAsia:Environmentaland ManagementPerspectives.RCU/EASTechnicalReportSeriesNo.6. United Nations Environment Programme, Bangkok. 26. Fuss,C.M.andKelly,J.A.,1969.Survivalandgrowthofseagrasses transplanted under artificial conditions. Bull. Mar. Sci., 19, pp.351-365. S ha bi Trung tm Hc liu - HTNhttp://www.lrc-tnu.edu.vn/ 27. Graeme J. Inglis, Michelle Waycott, 2001. Methods for assessing seagrass seed ecology and population genetics. Global Seagrass Research Methods. F.T. Short and R.G. Coles (editors). Elsevier Science B.V., pp.123-140. 28. HammerstromKKandWJKenworthy.2003.Anewmethodfor estimationofHalophiladecipiensOstenfeldseedbanksusingdensity separation.In press, Aquatic Botany. 29. HemmingaM.A.andDuarteC.M.,2000.Seagrassecology.Inpress, Cambridge University Press. 30. HootsmansM.J.M.,VermaatJ.E.andVanVierssenW.,1987.Seed-bank development,germinationandearlyseedlingsurvivaloftwoseagrass speciesfromtheNetherlans:ZosteramarinaL.andZosteranoltii Hornem. Aquat. Bot 28, pp.275-285. 31. Inglis,G.J., 2000a. Disturbance-related heterogeneity in the seed banks of amarine angiosperm. J. Ecol. 88, pp.8899. 32. KirkmanH.,1989.Restorationandcreationofseagrassmeadowswith specialemphasisonWesternAustralia.TechnicalSeries30. Environmental Protection Authority, Perth, Western Australia. 33. KuoandKirkman,1992.Fruits,seedsandgerminationinHalophila ovalis. Botanica Marina. Volume 35, Issue 3, pp.197204 34. Kuo and Kirkman, H. 1995. Halophila decipiens Ostenfeld in estuaries of southwestern Australia. Aquat. Bot. 51, pp.335340 35. Lee S.Y., 1997. Annual cycle of biomass of a threatened population of the intertidalseagrassZosterajaponicainHongKong.Mar.Biol129, pp.183-193. 36. Les D.H., Cleland M.A. and Waycott M.A., 1997. Phylogenetic studies in Alismatidae.II.Evolutionofmarineangiosperms(seagrasses)and hydrophily. Systematic Botany, 22: 443-63. S ha bi Trung tm Hc liu - HTNhttp://www.lrc-tnu.edu.vn/ 37. Lisitzin,A.P. (1986).Principelsofgeologicalmappingofmarine sediments(withspecialreferencetotheAfricancontinental margin). UNESCO Reports in Marine Science = Rapports de l'Unesco sur les sciences de la mer, 37. UNESCO: Paris, 101 pp. 38. Longstaff B.J. and Dennison W.C., 1999. Seagrass survival during pulsed turbidity events: the effects of light deprivation on the seagrasses Halodule pinifolia and Halophila ovalis. Aquat. Bot. 65, pp.105-121. 39. McMillan,C.,1976.Experimentalstudiesonoweringandreproduction in seagrasses. Aquat. Bot. 2, pp.8792. 40. McMillan,C.,1979a.Floweringundercontrolledconditionsby Cymodocea rotundata from the Palau Islands, Micronesia. Aquat. Bot. 6, pp.397401. 41. McMillan,C.,1979b.Floweringundercontrolledconditionsby Cymodoceaserrulata,Halophilastipulacea,Syringodiumisoetifolium, ZosteracapensisandThalassiahemprichiifromKenya.Aquat.Bot.8, pp.323336. 42. McMillan,C.,1982.Reproductivephysiologyoftropicalseagrasses. Aquat. Bot. 14, pp.245258. 43. McMillan,C.,1986.FruitsandseedsofHalophilaengelmannii (Hydrocharitaceae) in Texas. Contributions in Mar. Sci. 19, pp.18.44. McMillan,C.,1987.RecurrenceoffruitingofHalophilaengelmannii (Hydrocharitaceae)inRedshBay,Texas.ContributionsinMarine Science 30, pp.105108.45. McMillan,C.,1988a.TheseedreserveofHalophilaengelmannii (Hydrocharitaceae) inRedshBay, Texas.Aquat. Bot. 30, pp.253259. 46. McMillan,C.,1988b.TheseedreserveofHalophiladecipiensOstenfeld (Hydrocharitaceae) in Panama. Aquat. Bot. 31, pp.177182. S ha bi Trung tm Hc liu - HTNhttp://www.lrc-tnu.edu.vn/ 47. McMillanCandKSoong.1989.Anannualcycleofflowering,fruiting andseedreserveforHalophiladecipiensOstenfeld(Hydrocharitaceae) in Panama.Aquatic Botany 34, pp.375- 379 48. NelsonT.A.andWaalandJ.R.,1997.Seasonalityofeelgrass,epiphyte andgrazerbiomassandproductivityinsubtidaleelgrassmeadows subjected to moderate tidal amplitude. Aquat. Bot. 56, pp.51 - 74. 49. Orth R.J and Moore K.A., 1983. Seed germination and seedling growth of Zostera japonica L. in the Chesapeake Bay. Aqua. Bot. 56, pp.51 74. 50.Orth, R. J., M. C. Harwell, E. M. Bailey, A. Bartholomew, J. T. Jawad, A. V.Lombana,K.A.Moore,J.M.Rhode,andH.E.Woods.,2000.A review of issues in seagrass seed dormancy and germination: Implications forconservationandrestoration.MarineEcologyProgressSeries,200, pp.277-288. 51. PangalloR.A.andBellS.S.,1988.Dynamicoftheabove-groundand below-ground structure of the seagrass Halodule wrightii. Mar. Eco. Pro. Ser. 43, pp.297-301. 52. PetersenC.G.J.andBoysen-JensenP.,1911.ValuationoftheSea,I: Animal life of the Sea Bottom. Its Food and Quatity. Rerport of the Danish Biological Station, 20, pp.1- 81. 53. PhillipsR.C.andMeezE.G.,1988.Seagrasses.Publicationsofthe Smithsonan Institution. No 34. Washington D.C., 105 pages 54. Phillips C, C. P. McRoy, 1990.Seagrass Research Methods. Monographs on oceanographic methodology 9. UNESCO, prined in France. 210 p. 55. RollonR.N.andFortesM.D.,1991.Structuralaffinitiesofseagrass communitiesinthePhilippines.Livingresourcesinthecoastalareas, pp.333-346. 56. Setchell,W.A.,1924.Ruppiaanditsenvironmentalfactor.Proc.natn. Acad. Sci., 10, pp.286-288 S ha bi Trung tm Hc liu - HTNhttp://www.lrc-tnu.edu.vn/ 57. SfrisoA.andGhettiP.F.,1998.Seasonalvariationinbiomass, morphometricparametersandproductionofseagrassesinthelagoonof Venice. Aquat. Bot. 61, pp.207-223. 58. ShortF.T.,1987.Effectsofsedimentnutrientsonseagrasses:lit-erature review and mesocosm experiment. Aquat. Bot., 27, pp.41-57. 59. Short,F.T.,McKenzie,L.J.,Coles,R.G.andVidler,K.P,2002. SeagrassNet.ManualforScientificMonitoringofSeagrassHabitat. (QDPI, QFS, Cairns), 56p.60. F.Shortetal.,2007.Globalseagrassdistributionanddiversity:A bioregionalmodel.JournalofExperimentalMarineBiologyandEcology 350, pp.3-20. 61. Terrados,J.,Duarte,C.M.,Fortes,M.D.,Borum,J.,Agawin,N.S.R., Bach,S.,Thampanya,U.,Kamp-Nielsen,L.,Kenworthy,W.L.,Geertz-Hansen,O.,Vermaat,J.,1998.Changesincommunitystructureand biomassofseagrasscommunitiesalonggradientsofsiltationinSEAsia. Estuarine, Coastal and self Science. 46, pp.757-768.62. Verhagen J.H.G., Nienhuis P.H., 1983. A Simulation Model of production, seasonal changes in biomass and distribution of eelgrass (Zostera marina) in Lake Grevelinge. Mar. Eco. Pro. Ser. 10, pp.187-195. 63. Williams,S.L.1988.DisturbanceandrecoveryofdeepwaterCaribbean seagrass bed. Mar. Eco. Prog. Ser. 42, pp.63-71. 64.ZiemanJ.C.,BridgesK.W.andMcRoyC.P.,1978.Seagrassliterature Survey. In Dredged material Research Program, Technical Report, D 78 4, 213 pages. S ha bi Trung tm Hc liu - HTNhttp://www.lrc-tnu.edu.vn/ PH LC MT S HNH NH THC A V PHNG TH NGHIM Quang cnh khu vc nghin cu Thu mu S ha bi Trung tm Hc liu - HTNhttp://www.lrc-tnu.edu.vn/ ng gi mu Thu mu ht ging S ha bi Trung tm Hc liu - HTNhttp://www.lrc-tnu.edu.vn/ B tr th nghim Tng quan v o thng s mi trng S ha bi Trung tm Hc liu - HTNhttp://www.lrc-tnu.edu.vn/ Ma maSau ma ma ang phc hiMa kh Din bin theo thi gian (ma) ca c Xoan trong m nui thy sn S ha bi Trung tm Hc liu - HTNhttp://www.lrc-tnu.edu.vn/