B NNG NGHIP V PHT TRIN NNG THN

CC KHAI THC V BO V NGUN LI THU SN

VIN NGHIN CU HI SN

----------O0O----------BO CO CHUYN

C IM KHU H V CU TRC THNH PHN LOI, TR LNG QUN X NG VT THN MM KHU BO TN BIN PH QUNgi thc hin: KS. Thanh An

KS. Hong nh ChiuVin Nghin cu Hi sn

D n:

Xy dng Quy hoch chi tit Khu bo tn Ph Qu - Bnh Thun

Ch d n:

Cc Khai thc v Bo v ngun li thu snC quan thc hin:

Vin Nghin cu Hi sn

HI PHNG, 12/2010MC LC

3DANH MC CC BNG

4DANH MC CC HNH

5I. M U

7II. TNG QUAN TI LIU

71. Tnh hnh nghin cu ng vt y Vit Nam

152. Tnh hnh nghin cu nhm ng vt y ti 19 khu bo bin nghin cu

152.1. Tnh hnh nghin cu ng vt y C T Qung Ninh

162.2. Tnh hnh nghin cu ng vt y Ba Mn Qung Ninh

232.3. Tnh hnh nghin cu ng vt y o Trn Qung Ninh

242.4. Tnh hnh nghin cu ng vt y Ct B Hi Phng

282.6. Tnh hnh nghin cu ng vt y Hn M Thanh Ha

332.7. Tnh hnh nghin cu ng vt y Hn Mt Ngh An

332.8. Tnh hnh nghin cu ng vt y Hn La Qung Bnh

342.9. Tnh hnh nghin cu ng vt y Cn C - Qung Tr

362.10. Tnh hnh nghin cu ng vt y Sn Tr Hi Vn

382.11. Tnh hnh nghin cu ng vt y C Lao Chm Qung Nam

392.12. Tnh hnh nghin cu ng vt y L Sn Qung Ngi

412.13. Tnh hnh nghin cu ng vt y khu vc vnh Nha Trang

472.14. Tnh hnh nghin cu ng vt y Nam Yt Khnh Ha

482.15. Tnh hnh nghin cu ng vt y Hn Cau - Bnh Thun

512.16. Tnh hnh nghin cu ng vt y Ph Qu - Bnh Thun

522.17. Tnh hnh nghin cu ng vt y Cn o B Ra Vng Tu

572.18. Tnh hnh nghin cu ng vt y Ph Quc Kin Giang

612.19. Tnh hnh nghin cu ng vt y Th Chu Kin Giang

623. Tng quan v mi quan h gia phn b sinh vt y v ngoi cnh

623.1. Quan h gia phn b sinh vt y vi nhit v mn

633.2. Quan h gia sinh vt y vi trm tch y bin

644. Tng quan v nhng tc ng ca ng vt y ti cc vng d kin thit lp bo tn bin

644.1. Tc ng ca ng vt y ti h sinh thi o

654.2. Gi tr ca ng vt y trong pht trin ngnh du lch sinh thi

665. Tc ng ca con ngi ln h sinh thi ng vt y

666. Mt s gii php nhm qun l ng vt y ti cc vng o nhm phc v cho cng tc thit lp qun l

666.1. Cc gii php trong vic khai thc ng vt y trn vng rn san h

676.2. Cc gii php trong bo v h sinh thi cho ng vt y

676.3. Cc gii php trong vic nng cao nhn thc cng ng ti vng nghin cu

68III. NHN XT CHUNG

69TI LIU THAM KHO

DANH MC CC BNG

9Bng 1: Tng hp thnh phn loi ca ngnh, lp ng vt y cng b

14Bng 2: Sinh vt lng bnh qun mt s vng ven bin

14Bng 3: Sinh vt lng bnh qun ca mt s nhm sinh vt y ch yu

18Bng 4: Cu trc thnh phn loi thn mm

19Bng 5. Sinh vt lng thn mm vng triu khu vc Ba Mn

22Bng 6: Cu trc thnh phn ng vt da gai o Ba Mn

34Bng 7: Thnh phn loi phn b ca lp sao bin, hi sm, cu gai trn vng rn san h Cn C

34Bng 8: Thnh phn phn b nhuyn th trn vng rn san h ti Cn C

38Bng 9: Sinh vt lng ng vt y khu vc o Sn Tr

42Bng 10: Thnh phn loi nhm ng vt da gai phn b ti Hn Mun-Nha Trang

45Bng 11: S bin i phong ph ca Cu gai Diadema qua cc nm 2002-2005 trong KBTB vnh Nha Trang theo phng php phn tch bin n yu t ( t do 1, gi tr ti hn 3.9)

46Bng 12: S lng c th ca mt s loi ng vt khng xng sng chn la ghi nhn c trong KBTB vnh Nha Trang ti 8 im gim st t 2002-2005

50Bng 13: Nhm ch th ng vt y c ln trong rn san h C Lao Cau

52Bng 14: Cu trc thnh phn loi ng vt Da gai khu bo tn bin Ph Qu

55Bng 15: Bng so snh thnh phn loi da gai ti Cn o

56Bng 16: Thnh phn loi phn b ca nhm da gai trn vng rn san h Cn o

56Bng 17: Thnh phn phn b nhuyn th trn vng rn san h Cn o

59Bng 18: Thnh phn loi phn b ca nhm da gai trn vng rn san h Ph Quc

60Bng 19: Thnh phn loi nhuyn th vng rn san h Ph Quc

DANH MC CC HNH

20Hnh 1: Phn b thnh phn loi thn mm khu vc o Ba Mn

22Hnh 2: T l phn trm thnh phn loi ca khu h Da gai

25Hnh 3: T l thnh phn loi ca cc nhm hi sn khai thc ch yu ti vng bin Ct B

35Hnh 4: Cu gai en Diadema setosum ti Ph Quc v Echinostrephus aciculatus ti Cn C

36Hnh 5: Biu bin ng mt nhm ng vt khng xng sng Cn C

45Hnh 6: phong ph trung bnh ca tt c cc ng vt khng xng sng chn la (ngoi tr sao bin gai), tt c cc loi Da gai v cu gai en trn 100m2 din tch mt ct, KBTB vnh Nha Trang, 2002-2005

46Hnh 7: phong ph trung bnh ca sao bin gai v hi sm bin trn 100m2 din tch mt ct, KBTB vnh Nha Trang, 2002-2005. Ghi ch: Mean abundace: phong ph trung bnh; COTS: sao bin gai; Sea cucumber: hi sm

47Hnh 8: phong ph trung bnh ca nhm thn mm bao gm cc nhm khai thc nh c n Trochus v trai tai tng Tridacna trn 100m2 din tch mt ct, KBTB vnh Nha Trang, 2002-2005. Ghi ch: mean abundance - phong ph trung bnh; Molluscs Thn mm; Trochus - c n; Clams - Trai

53Hnh 9: Biu bin ng mt nhm ng vt y Cn o

57Hnh 10: Biu bin ng mt nhm ng vt y Ph Quc

I. M URn san h l mt h sinh thi in hnh v quan trng nht trong cc h sinh thi bin o, rn san h c tm thy trn 100 quc gia v cc vng lnh th nm vng nhit i v cn nhit i (Hodgson, 2000). Rn san h trn ton th gii c khong 6 x 105 km2, v chim khong 0,1% din tch b mt tri t (Smith, 1978). Rn san h tham gia hnh thnh v bo v hng ngn hn o ln nh trn ton th gii v c ngha tht s quan trng i vi cng ng dn c nhiu o v vng ven bin, trong phng din bo tn t ai v phc v cuc sng con ngi (V S Tun, 2003). Vit Nam c khong 1.100km2, trong 45% din tch ph rn l san h sng. y l iu kin thun li cho qu trnh pht trin kinh t x hi, du lch ang v s l hng pht trin trng tm. H sinh thi rn san h l iu kin tt cho nhiu loi sinh trng v pht trin. Trong , nhm ng vt y c ln lun chim a s c v thnh phn loi, s lng cng nh sinh khi.

ng vt y (V) trong h sinh thi bin o l mt trong nhng ngun thc phm c chp lng cung cp trc tip cho con ngi, gi tr thng mi, du lch phc v cho ch bin thu, hi sn xut khu v c trong y hc nh cc loi hi sm, bo ng... Hin nay, nhng nghin cu v ng vt y c tin hnh nghin cu trn nhiu quy m khc nhau, trn nhiu i tng khc nhau. c bit l tin hnh nghin cu trn i tng c gi tr kinh t, c sn lng khai thc cao, trong ch yu l nhm ng vt y c ln vng ven b, nh mt s loi hi sm, mt vi loi gip xc, c, mt s ng vt hai mnh v c gi tr kinh t. Tuy nhin, cc cng trnh nghin cu ng vt y c ln ti cc h sinh thi vng bin o cn rt t hoc ang tp trung ti cc vin nghin cu trn c nc cha c cng b rng ri, cc nghin cu cn mang tnh khi qut, tng hp cha i vo tng nhm i tng. Cc thng tin khng theo h thng v nhiu thng tin cn thiu trong qu trnh thu thp, to lp c s d liu phc v cho mc ch quy hoch, bo v cc gi tr a dng loi phn b v gi tr kinh t vi mc tiu bo tn v khai thc ngun li lu di, bn vng.

Ngun li sinh vt bin ang b khai thc mi lc, mi ni ti cc vng ven b, ven o. Nhiu loi c gi tr cao nh tm hm, hi sm, bo ng l nhm loi tp trung nhng vng nc nng ven o c bit l trong cc rn san h ang b khai thc trit , vng rong c bin, vng triu. Kh nng khai thc v nh bt qu mc trong cc h sinh thi lm cho cc h sinh thi, c bit l h sinh thi san h ang c du hiu suy gim, nh hng nhiu n cc loi sinh sng ph thuc vo cc h sinh thi, l mi e do ln cho nhiu loi sinh vt bin.

Bo co ny da trn cc thng k ti liu lin quan n cc c trng c bn v thnh phn loi, c im phn b, mt v khi lng ca ng vt y trn rn san h v vng bin ven 19 o lm c s cho cng tc bo tn tnh a dng sinh hc rn san h phc v nghin cu, du lch cng nh cung cp c s d liu cho cc nghin cu v nhm ng vt y.

II. TNG QUAN TI LIU

1. Tnh hnh nghin cu ng vt y Vit Nam

Nguyn Vn Chung, o Tn H, 1978 thng k ton b cc cng trnh nghin cu h ng vt y bin Vit Nam, tc gi thng k c 74 cng trnh nghin cu trn ton lnh th v tiu biu trong cc cng trnh nghin cu l ca cc tc gi nc ngoi v chuyn tu kho st lin kt gia Vit Nam - Trung Quc. Cc cng trnh c th k n l: Cng trnh nghin cu ca R. Srne, C. Dawydoff t nm 1930 - 1952. E.F. Gurjanova v i iu tra Vit-Trung t nm 1959 -1962 c nhng ng gp ng k trong kt qu chung v thnh phn khu h ng vt y bin Vit Nam. Tc gi thng k c 6377 loi ng vt y bin Vit Nam trong c 1064 loi cha c cng b v 667 loi cha xc nh c. Trong s cc loi trn c 925 loi c cng b m t, s cn li 4388 loi c cng b danh mc. Trong s cc loi cng b c mt ging mi, 372 loi mi v mt dng mi. C th ca tng ngnh, lp c trnh by di y:

- Ngnh Hi min: c 160 loi, trong c 18 loi cha xc nh, 123 loi cng b danh mc, 28 loi cng b m t, 9 loi cha cng b v c 8 loi mi c tng hp t 5 cng trnh ca Dawydoff, Lvi, Gurjanova v Trn Ngc Li.

- Ngnh Rut khoang: c 714 loi, trong c 32 loi mi, mt dng mi, 33 loi cha xc nh, 547 loi cng b danh mc, 114 loi cng b m t v 23 loi cha cng b c tng hp trong tng s 15 cng trnh ca Dawydoff, Hickson, Leloup, Pax v Muller, Trn ngc li, Vin nghin cu bin nay l Vin nghin cu Hi Sn.

- Ngnh giun vi: c 10 loi cng b danh mc trong c mt loi cha xc nh c tng hp t 2 cng trnh ca Dawydoff v Gurjanova.

- Ngnh giun t: Lp giun nhiu t: c 743 loi trong c 1 ging mi v 45 loi mi, 135 loi cha xc nh, 488 loi cng b danh mc, 176 loi cng b m t v 79 loi cha cng b trong tng s 15 cng trnh nghin cu ca Dawydoff, Fauchald, Fauvel, Gallardo, Gurjanova, Srne, Strelzov, Uschakov, Trn Ngc Li, Nguyn Vn Chung, Vin nghin cu bin.

- Ngnh Sipunculida: c 32 loi, trong c 5 loi cha xc nh, 21 loi cng b danh mc, 11 loi cng b m t, trong tng cng 6 cng trnh ca Dawydoff, Gurjanova, Trn Ngc Li.

- Ngnh Uchiuria: c 6 loi cng b danh mc, 2 loi cha xc nh, c tng hp trong 3 cng trnh ca Dawydoff, Gurjanova, Trn Ngc Li.

- Ngnh ng vt hnh ru: c 100 loi c cng b danh mc, trong c 10 loi cha xc nh, c 4 loi mi, c tng hp trong 3 cng trnh ca Dawydoff, Gurjanova, Trn Ngc Li.

- Ngnh tay cun: c 6 loi cng b danh mc, c tng hp t 2 cng trnh ca Dawydoff v Srne.

- Ngnh thn mm: c 2523 loi trong c 154 loi cha xc nh, 1632 loi cng b danh mc, 308 loi cng b m t, 583 loi cha cng b, trong s loi cng b c 200 loi mi c tng hp t 19 cng trnh nghin cu ca Bavay, Dautzenberf & Fischer, Marche-Marchard, Risbec, Robson, Saurin, Srne Hayashi, Trn Ngc Li, Nguyn Vn Chung, nh nh Tin, Vin Nghin cu bin., Dawydoff.

- Ngnh chn khp, lp gip xc: c 1647 loi trong c 264 loi cha xc nh, 1044 loi cng b danh mc, 248 loi cng b m t, c 38 loi mi v 355 loi cha cng b, c tng hp t 46 cng trnh ca Boschma, Fize, Pize & Srne, Forest, Gravier, Dawydoff, Gurjanova, Monod, Starobogatov, Tiwari, Hayashi, Trn Ngc Li, Nguyn Vn Chung, nh nh Tin, Vin Nghin cu bin.

- Ngnh da gai: c 384 loi c 39 loi cha xc nh, 359 loi cng b danh mc, 10 loi cng b m t, 15 loi cha cng b c tng hp trong 8 cng trnh ca Srne, Hayashi, Trn Ngc Li, Nguyn Vn Chung, nh nh Tin, Vin Nghin cu bin, Dawydoff.

- Ngnh Hemichordata: c 6 loi cng b danh mc, c 2 loi cha xc nh, c tng hp t cng trnh ca Dawydoff.

- Ngnh Chordata: c 46 loi cng b danh mc, 1 loi cha xc nh, c tng hp t 4 cng trnh ca Srne, Trn Ngc Li, Nguyn Vn Chung, Gurjanova, Dawydoff.

Bng 1: Tng hp thnh phn loi ca ngnh, lp ng vt y cng b

S

T

TNgnhTng s

loiS loi cha cng bS loi cng b danh mcS loi cng b m tS loi cha xc nhS

cng trnh nghin cu

Cc loi mi

Dng miGing miLoi mi

1Ngnh Hi min1609123281858

2Ngnh Rut khoang714235471143315132

3Ngnh Giun vi101012

4Ngnh Giun t, lp Giun nhiu t743794881767915145

5Ngnh Sipunculida32211156

6Ngnh Echiuria6623

7Ngnh ng vt hnh ru1001001034

8Ngnh tay cun662

9Ngnh chn khp, lp gip xc146735510442482644638

10Ngnh thn mm2523583163230815419200

11Ngnh da gai3841535910398

12Ngnh Hemichordata6621

13Ngnh Chordata464614

Ngun: (Nguyn Vn Chung v nnk, 1978)

Tm li c th thy 6377 loi c thng k t 77 cng trnh l mt con s ln so vi nhng iu kin nghin cu trc v n ch yu c tin hnh bi cc nh nghin cu nc ngoi trong tiu biu l cc tc gi Srne, Dawydoff, Gurjanova v mt s nh nghin cu trong nc tiu biu nh Nguyn Vn Chung, Trn Ngc Li. Tuy nhin, nhng nghin cu ny cn nhiu hn ch nh tp chung vng triu v vng ven b ca mt s a phng ring l, phm vi hp v ch c ba cuc iu tra trn quy m ln nh tu De lanessan (1929 - 1931), i iu tra Vit Trung (1959-1960, 1962) v Vit X (1960 1961). Mt khc, bn cnh nhng ngnh, lp c cc chuyn gia tp chung nghin cu nhiu nn s loi pht hin nhiu nh thm mm (2523 loi), gip xc (1647 loi), giun nhiu t (743 loi), cn nhiu ngnh, lp cha c nghin cu nhiu nh hi min, rut khoang, da gai v trong ch c hai vng bin c nghin cu nhiu l Vnh Nha Trang v Vnh Bc b. Hn na cc cng trnh trn c nghin cu tng hp nhiu i tng cho ton vng bin Vit Nam v ch yu s dng phng php thu mu im bng gu Petersen ch tnh c lng sinh vt y c nh, trong giun nhiu t chim s lng chnh v mt phn b ca sinh vt y.

Nguyn Vn Chung, 1994, tc gi li tng hp cc cng trnh nghin cu v ng vt y ti vng bin vit nam, nhng ch yu l v mt phn b ca cc loi. Tc gi tng hp t hn 100 bo co ca cc tc gi v cng trnh nh: Nhiu tc gi nh Dawydoff,C., Serene, R., Gurjanova E.F. v i iu tra Vit-Trung (hp tc Vit Trung iu tra vnh Bc B) c nhiu cng trnh nghin cu ng gp vo nghin cu thnh phn loi sinh vt y bin Vit Nam. V nghin cu sinh thi khu h V di triu, kt qu iu tra tng hp vnh Bc B do hp tc Vit Trung (1959 1960 v 1962) v Vit X (1960 -1961), gii thiu v thnh phn loi, phn b, sinh vt lng v cc c im khu h ng vt y vnh Bc B t su hn hn 20m. Nm 1962-1964, Tng cc Thu Sn tin hnh iu tra b sung sinh vt y vng gn b Ty vnh Bc B. Nm 1974, Nguyn Vn Chung, Nguyn Xun Dc iu tra sinh vt y ven b bin Qung Ninh-Hi Phng su khng qu 30m vi mc ch gp phn hon thin khu h sinh vt y vnh Bc B. Nguyn Vn Chung, o Tn H v ctv iu tra khu h sinh vt y vnh Bnh Giang-Nha Trang (1978) v vng bin Thun Hi-Minh Hi (1981). Nm 1981-1985, trong chng trnh hp tc Vit-X nghin cu h sinh thi ven bin nam Vit Nam, tc gi i su v qun x sinh vt y trn y mm. Trong chng trnh nghin cu bin 1986-1990, trn c s kt qa nghin cu bao gm s liu thu c v sinh vt y trn tu Bin ng (1979-1980) vng bin Nam Vit Nam, cng vi kt qu mi thu c, cc tc gi Nguyn Vn Chung, o Tn H v ctv tin hnh nghin cu tng hp, gp phn hon chnh khu h sinh vt y ton vng bin Vit Nam.

Tng s loi pht hin dc cho thy thnh phn loi phn b ca ng vt y trn vng bin Vit Nam nh sau:

- vnh Bc B (t v 170 tr ra) s loi chim khong 20%.

- bin min Trung v Nam B (t v 170 tr vo) s loi chim khong 50%.

- S loi pht hin c c 3 vng chim khong 30%.

- Thnh phn loi bin min Trung v pha Nam khng khc bit my v c xu th tng dn t Bc xung Nam. Thnh phn loi c ngun gc v c tnh phn b a l rng hu khp cc vng bin th gii, ngoi tr mt s t loi phn b ton cu (Cosmopolite), c kh nng thch nghi cao vi iu kin sng, cn li phn ln s loi ch phn b rng vng nhit i n - Ty Thi Bnh Dng.

c im phn b ca mt s nhm ng vt y chnh ti vng bin Vit Nam nh sau:

Phn b ca giun nhiu t (Polychaeta): Nhm giun nhiu t chim v tr kh quan trng trong khu h ng vt y bin Vit Nam, tuy thnh phn loi khng nhiu nh thn mn v gip xc, nhng pht hin c khong 700 loi. Trong mt s h c s loi tng i nhiu nh h Aphroditidae, Nereidae, Eunicidae, syllidae, Terebellidae, Capitellidae, Nephtyidae Phn ln giun nhiu t thch ng vi dng cht y l bn nhuyn, c bit c loi sng cht y l ct ln hoc ct c ln v sinh vt, nhiu loi sng trong cc tng san h cht. S phn b ca giun nhiu t khc hn vi thn mm, gip xc v da gai. Nhiu loi giun nhiu t phn b rt rng trong c mt s loi c phn b ton cu nh Terebellides stroemi, Sternaspis scutata, Nephtys dibranchishoc phn b rng khu bin nhit i n -Thi Bnh Dng nh Marphysa stragulum, Chloeia, Panthalis melanonotus. bin Vit Nam ngoi cc loi phn b rng nh ni trn, tng vng bin c thnh phn loi c trng khc nhau:- vnh Bc b pht hin khong 300 loi, cc loi c trng l Phyllidoce castanea, Eunice tubofex, Notomastus latericeus, Glycera riuxii

- ven bin min Trung pht hin gn 400 loi, cc loi c trng l Amphinome rostrata, Glycera alba, Glycera capitata, Prionospio malayensis, Sthenolepis japonica...- Vng bin min Nam pht hin c 200 loi, cc loi c trng l Micronephtys sphaerocirrata, Thalenessa trpica, Onuphis eremita, glaophmus orientalis...Phn b ca ng vt thn mm (Mollusca): ng vt thn mm c thnh phn loi nhiu nht trong cc nhm ng vt y, n nay pht hin c gn 2500 loi thuc 163 h, trong mt s h c s loi tng i nhiu nh: Pyramidellidae, Veneridae, Conidae, Muricidae, Cypraeidae, Nassidae, Pectinidae, Arcudae Thn mm phn b hu ht cc loi cht y, t tng ven bin n vng bn nhuyn c su vi chc mt. Phn b trn mt rng cng c s khc nhau tng vng bin:

- vnh Bc B pht hin c gn 1000 loi, cc loi thng gp l Distorsio reticulata, Bursa rana, Murex tiapa, Amussium pheuronectes, Drupa margariticola, Turricula tuberculata, Angulus vestalis

- Bin min Trung thnh phn loi thn mn rt phong ph, pht hin c gn 1500 loi, cc ging loi thng gp l: s (Arca), hu (Ostrea), Cardium pulcherum, Cerithium kochi, Natica chilensis, Surcula tuberculata, Tellina radiata, Terebellum terebellum, Pinna vexillum, P. nigra, Trai tai tng (Tridacna squamosa, T. crocea), c n (Trechus niloticus, Tectus pyramis)

- Vng bin pha Nam pht hin c khong 500 loi cc loi thng gp l Turbo bruneus, Nerita albicilla, Thais acleata, Arca antiquata, Chlampys nobilis, Strombus succinctus.

Phn b ca gip xc (Crustacea): ng vt gip xc c s loi v s lng c th tng i nhiu, c bit trong mu ko li ng vt y, y l mt c trng ca khu h sinh vt y vng bin nhit i. n nay xc nh c khong 1500 loi thuc 70 h, trong mt s h c s loi tng i nhiu nh: Xanthidae, Gonoplacidae, Leucosidae, Portunidae, Ocypodidae, Majidae, Penaeidae.

- vnh Bc B pht hin c hn 500 loi, ngoi cc loi trn, cc loi sau y cng thng gp vng bin ny: Parapenaeopsis tenella, Chasmocarcinops gelasimoides, Charybdis truncata, Scalopidia spinoisipes, Leucosia unidentata

- Vng bin min Trung pht hin c khong 700 loi trong cc loi in hnh nh Penaeus monodon, P. semisulcatus, P. latisulcatus, Macrophthalmus nudus, Panulirus ornatus, P.homarus, P. longipes, P. stimpsoni

- Vng bin pha Nam pht hin c gn 500 loi, ngoi mt s loi c gi tr kinh t trong h tm he, cua bi v tm hm, cn c cc loi thng gp khc nh: Actumnus spuamosus, Cryptosoma granulosa, Chasmocarcinops gelasimoides, Myra fugax, Myrodes eudactylus.Phn b ca Da gai (Echinoderm): ng vt da gai c s loi t nht trong s 4 nhm ng vt y, ch yu sng bin. n nay pht hin c khong 350 loi thuc 58 h, trong mt s h c s loi tng i nhiu nh: Comasteridae, Holothuriaidae, Cucumariidae, AmphiuridaeCc loi thng gp trn vng triu v di triu c nn y cng (ct v san h cht) l hi sm (h Holothuridae), sao bin v cu gai c ln. Trong san h cht thng c cc loi ui rn h Ophiothrichidae v Ophiactidae

- min trung pht hin hn 200 loi, cc loi thng gp l Laganum decagonale, Ophiura pteracantha, Leptopentacta tyica, Luidia prionota, Astropecten velitaris, Clypeaster reticulatus, Ophiothela danae

- Vng bin pha Nam t hn, khong gn 100 loi, thng gp c cc loi Ophiactis savignyi, Pentacta anceps, Holothuria spinifera, Echinodiscus auritus, Lobenia elongata, Peeinella lesueuri

Phn b sinh vt lng ca vng bin Vit Nam cho thy: Tng sinh vt lng bnh qun bin Vit Nam l 6,35 g/m2 v 9,4 c th/m2. Nu so snh vi khu vc thm lc a ca vng bin n i pha Bc, sinh vt lng sinh vt y bin Vit Nam kh thp. Do iu kin mi trng v cht y khc nhau nn s phn b sinh vt lng khng u, biu hin cc c im sau:

- vnh Bc B, sinh vt lng trung bnh l 8,51 g/m2 v 70,76 c th/m2, trong da gai v gip xc chim u th v khi lng, cn mt do gip xc v giun nhiu t. S phn b ca khi lng sinh vt trong vng bin rt khc nhau. Vng c khi lng bnh qun cao trn 15 g/m2 phn b pha Bc, ng Vnh, Pha Ty o Bch Long V v mt khu nh ven bin Bnh Tr Thin. Vng pha Ty o Bch Long V c cht y ct, cc loi c lng tim (Branchiostoma belcheri v Asymmetron cultellum) chim u th tuyt i. Vng ven b pha Ty Vnh, khi lng sinh vt cng tng i cao, gn 10 g/m2, trong Gip xc chim u th nh cc loi Chasmocarcinops gelasimoides, Typhlocarcinus nudeu, ngoi ra loi gip xc ui lch Upogobia sp v nhng loi cua nh khc cng c khi lng kh cao.

- Vng c mt cao (trn 100 c th/m2) c xu th trng vi vng c khi lng cao, bao gm vng pha Bc Vnh vng o Bch Long V v vng ven b Ngh Tnh, c bit vng Bch Long V c trm t ti 700 c th/m2. Nhiu kt qu iu tra vng st b Ty vnh Bc b su khng qu 20m u cho thy khi lng sinh vt tng i cao (trn 10g/m2).

- vng bin min Trung ( Nng - Phan Rang) do dc ln, cch b khng xa c su rt ln, nn sinh vt lng nhn chung thp. Vng c sinh vt lng di 1,00 g/m2 v 50 c th/m2 chim phn ln din tch. Tuy vy vng st b hoc vng vnh lng sinh vt cao hn nh vnh Bnh Giang - Nha Trang (5,19 g/m2 v 191,6 c th/m2) v vnh Vn Phong-Bn Gi (30,54 g/m2v 191,6 c th/m2).

- vng bin pha Nam (t Phan Rang tr vo) c sinh vt lng bnh qun l 4,05 g/m2 v 131,09 c th/m2. Khi lng thp hn, nhng mt li cao hn so vi vnh Bc b, bi l trong thnh phn nh lng hai nhm c kch thc nh l gip xc v giun nhiu t chim u th.Bng 2: Sinh vt lng bnh qun mt s vng ven binVng binThi gian iu traKhi lng bnh qun (g/m2)Mt bnh qun (c th/m2)

Vng khi trn 20 mVnh bc b1959 19748,5170,76

Bin min Trung1979 19860,244,79

Bin pha Nam1977 19854,05131,09

Vng st bVen bin Qung Ninh Hi Phng1971 197220,71139,20

Vnh Nha Trang Vn Phong1976 198517,90165,61

Bng 3: Sinh vt lng bnh qun ca mt s nhm sinh vt y ch yu

Vng bin

Nhm loiThun Hi Minh Hi

(1979 1980)Nha Trang Vn Phong

(1976 1985)Vnh Bc b

(1959 1962)Qung Ninh Hi Phng

(1971 1972)

g/m2C th/m2g/m2C th/m2g/m2C th/m2g/m2C th/m2

Giun nhiu t0,94159,900,8962,581,1330,601,2450,10

Thm mm2,8016,805,2929,531,254,6010,7020,90

Gip xc1,41199,301,8343,903,0046,502,6143,80

Da gai3,1314,309,1418,283,219,402,1412,50

Loi khc0,2310,600,7511,322,4412,403,9912,10

Tng s8,50401,2017,90165,6111,03103,2020,71139,40

2. Tnh hnh nghin cu nhm ng vt y ti 19 khu bo bin nghin cu

Nghin cu v ng vt y c nhiu tc gi trong v ngoi nc tin hnh rt nhiu trn phm vi c nc v trn ton lnh th Vit Nam. Tuy nhin cc nghin cu v nhm ng vt y trn vng rn san h ti cc o cn t c tin hnh nghin cu v nht l phng php nghin cu ln c kh ti th t c thc hin hn. Cc nghin cu v nhm ng vt y trn vng rn san h thi gian trc y ch mi c cc nh nghin cu Min Nam thc hin, m trong ch yu l do Vin hi dng hc Nha Trang thc hin. Trong cc nh nghin cu ca Vin hi dng hc Nha Trang c tc gi o Tn H l tc gi c nhiu cng trnh nghin cu v nhm ng vt y trn vng rn v tp trung l nhm ng vt da gai. Tuy nhin, tc gi mi ch thc hin ti cc o pha Nam nh Cn o v Ph Quc cn cc o Bch long V v Cn C th cha c tin hnh nghin cu. Mt s cng trnh nghin cu tiu biu c th k n l cng trnh nghin cu S b nghin cu ng vt da gai vn o Th Chu, Ph Quc, 1992; thnh phn loi ng vt da gai vng bin Cn o, 1996; tc gi v cng tc vin cho xut bn 2 tp danh mc ng vt da gai vng bin Vit Nam, 1994.2.1. Tnh hnh nghin cu ng vt y C T Qung Ninh

Kt qu phn tch mu thu trong t kho st ca ti v tham kho cc t liu c c t nm 1973 n nay (N.V. Chung, N.X. Dc, P.. Trng, 1973; 1947, 1948; .C. Thung, 2000, 2001), C T - Thanh Ln pht hin c 208 loi thuc 128 ging, 63 h. Trong ngnh Thn mm (Mollusca) c s loi phong ph nht vi 151 loi, chim 72,9% tng s loi, sau n Gip xc (Crustacea) 36 loi 17,4%, Giun t (Annelida) 15 loi, chim 7,2% v thp nht l ngnh Da gai (Echinodermata) ch c 5 loi chim 2,4%.

Theo kt qu phn tch v thng k ca Vn Khng v cs (2008) v s phn b ca V vng bin C T - Thanh Ln trn cc mt ct kho st cho thy mt s phn b khng ng u gia cc mt ct. Hu ht cc bi ct s lng loi ch nm trong khong t 10 25 loi, cao nht thuc v bi Nam Hi v Hng Vn cng ch tm thy 18 25 loi. Trn cc bi triu rn , chim u th v thnh phn loi, hn 100 loi tm thy dng sinh cnh ny. Bi triu rng ngp mn, phn b ch yu pha ng Bc o C T Ln, do rng ngp mn mc trn ct, nn rng rt tha tht, nn y l ct, h sinh vt y tng i ngho. Tng s loi pht hin c 15 loi, cc loi in hnh gm Cerithidea cingulata, Littorinopsis scabra (c), cua ging Sesarma spp., Scopimera bitympana, S. tuberculata .v.v. Vng di triu: pht hin 90 loi phn b khu vc ny, trong s ny thn mm chim s loi nhiu hn c, trong :- Ngnh Thn mm (Mollusca) c 62 loi, chim 68,8%.

- Ngnh Giun t (Annelida) vi lp Giun nhiu t (Polychaeta) c 6 loi, chim 6,7%.

- Ngnh Chn t (Arthropoda) vi lp Gip xc (Crustacea) c 17 loi, chim 18,9%.

- Ngnh Da gai (Echinodermata) c 5 loi, chim 5,6%.

- Cc loi ng vt y in hnh v c gi tr cao nh Bo ng (Haliotis diversicolor), Trai ngc (Pinctada martensii), Bn mai (Pinna antenuata, Pinna atropurpurea), c Nn (Trochus maculatus, T. pyramis), h c S (Cypreidae), h Cua bi (Portunidae), h tm He (Peneidae), Sao bin (Astropecten polycanthus, A. monocanthus).

- Cc loi ng vt y qu him: Trai ngc (Pinctada margaritifera), Vm xanh, con St (Anomalodiscus squamosa), c n ci (Trochus niloticus), c n c (Trochus pyramis), Bo ng (Haliotis diversicolor) (cc loi ny l nhng loi c s lng t, hin ang b khai thc mnh c nguy c dit vong, cn phi c bin php bo v), con 3 kha (Gafrarium tumidum), mc Nang vn h (Sepia tigris).2.2. Tnh hnh nghin cu ng vt y Ba Mn Qung Ninh

- Giun t: Tp hp cc kt qu nghin cu c c, cho n nay ring v giun nhiu t thng k c 60 loi thuc ngnh giun t, trong lp Giun nhiu t c 58 loi v lp Su t c 2 loi. S loi trn thuc vo 48 ging v 25 h. Nhn chung, s loi trong cc ging hay h u thp, ch khong 3 - 5 loi. Rt nhiu ging hay h ch c 1 loi. Nhn chung, s loi Giun nhiu t trn th hin tnh thch nghi vi hai th nn y chnh l y mm vng ngp nc v y cng trong cc thn san h. S loi thu c trn vng triu t do cc bi triu trong khu vc l cui nn Giun t phn b.So snh vi cc vng bin khc trong khu vc thy rng, khu vc Ct B c iu tra y hn cc vng khc nn pht hin c 110 loi (KT0311), vng vnh H Long - 57 loi (KNCF-Vit Nam). Qua ta thy, thnh phn loi khu h giun nhiu t ca vng o Ba Mn kh phong ph. Nu c iu tra k hn, th s loi c th t khong 80 - 100 loi.S phn b ca Giun nhiu t ph thuc nhiu vo c im nn y. o Ba Mn c cu trc a cht kh a dng, bao gm cc o t c nn y l ct kt v cc o vi. Trong khi cc o t c nn y vng triu l cui, nn y khng n nh nh cc o vi nn cc loi giun nhiu t phn b quanh cc o c khc nhau. qua c th xem xt nh gi c im phn b ca chng. Cc sinh cnh phn b ca giun nhiu t bao gm:

- Phn b trn cc vng triu cui - si: Vng triu c nn y l cui si rt ph bin khu vc Ba Mn. Trn khu cao triu v trung triu l cc hn tng, cc bi ct. Trn cc bi triu ny, thnh phn loi ca Giun nhiu t kh ngho nn, ti mi im kho st ch pht hin thy 2 - 7 loi, sinh lng cng rt thp nn trong cc mu nh lng hu nh khng thu c, c bit l pha ng cc o. iu ny cng c khng nh t cc nghin cu trc y (1999). c bit trn vng cao v trung triu th hu nh khng c. Tuy nhin, trn cc tng nm trn vng triu c cc khm hu xp tng tng lp lp nhiu khe rnh, trong c tch t mn b hu c c pht hin nhi loi Giun nhiu t thuc cc ging khc nhau, mt t ti 15 - 20 con/m2 cn sinh khi ca chng thng thp, khong 2,0 g/m2.

- Phn b trn cc bi triu y mm: Cc bi ct phn b hn ch mt s khu vc. ng ch hn c l do pha bc o Cnh Cc v mt s ch lm khc. Ct c cp ht nh th dn t cao triu n thp triu. Thnh phn loi Giun nhiu t trn cc bi triu ct thng ngho nn do sau khi triu rt i ct b phi kh nn giun khng sng c do thiu m. Thng ch pht hin 1 -2 loi trn vng thp triu ca kiu cht y ny.

Cc bi triu ct - bn phn b thng nm trong nhng vng lm quanh cc o, vi i cao triu v phn trn ca i trung triu l mt do rng ngp mn hp v thp. Cc bi triu ct - bn thng gi c m cn thit Giun nhiu t sinh sng. Mt khc, nh c do rng ngp mn pha trn nn chng c lng mn b hu c cn thit lm thc n. V vy, thnh phn loi ca khu h Giun nhiu t trong kiu cht y ny phong ph hn. Trn vng triu chng thng phn b ph bin hn trn vng cao v trung triu do nn y ti xp hn, cn vng thp triu do nn y ch yu l bn nn thng b nn cht nn giun hu nh khng phn b. ng ch hn l trong vng rng ngp mn cn thu c 2 loi Giun t khc thuc lp Sipunculida l s sng v bng tha l nhng loi c gi tr kinh t cao.

- Phn b ca Giun nhiu t trn vng rn san h: Rn san h l mt h sinh thi c trng, vi c im l nhiu hang hc, khe rnh nn rn san h rt phong ph ni c tr v thc n cho cc loi sinh vt y, trong c Giun nhiu t. Chng c th bm vo cc cy san h sng, c l trong cc tng san h cht, chui rc trong cc khe rnh trn cc tng c rong, san h bao ph hay trong cc hm c ct san h tp trung li. Kt qu kho st cho thy, trn vng rn san h, giun nhiu t cn phn ra cc nhm sinh thi sau:

* Nhm loi ly thn san h lm gi th bm;

* Cc loi sng c trong cc thn san h cht;

* Cc loi sng trong cc khe rnh ca nn y trn rn.

- ng vt thn mm: Kt qu nghin cu cho thy thn mm l nhm V chim s lng ln vi tng s 197 loi. Trong nhm ny, lp Chn bng (Gastropoda) gm 97 loi, chim 49,2 %, lp Hai mnh v (Bivalvia) 96 loi - 48,8 %, lp Chn o (Scaphopoda) 2 loi - 1%, lp Nhiu tm (Song kinh) (Polyplacophora) 2 loi - 1 % (bng 4).

Bng 4: Cu trc thnh phn loi thn mmTaxonS hS gingS loiT l

Polyplacophora1221

Scaphopoda1221

Gastropoda28519749,2

Bivalvia27579648,8

Tng s57112197100

- Lp Chn bng: c 97 loi thuc 28 h, 51 ging, cc h c s loi nhiu bao gm h c n (Trochidae) vi 15 loi, Cerithiidae -11 loi, c xng (Muricidae) - 11 loi), c vng triu (Littorinidae) - 9 loi; cc h cn li c t 1 n 6 loi. Cc loi thng gp l Cerithidea cingulata, Littoraria intermedia, Nodilittorina pyramidalis, Planaxis sulcatus, Nerita albicilla, Clypemorus biscilatus, Chicoreus torefactus, Trochus pyramis...

- Lp hai mnh v: pht hin 96 loi thuc 27 h, 57 ging. H Veneridae c s loi nhiu nht, 26 loi. Ba h c s loi tng i nhiu gm h Tellinidae - 9 loi, Ostreidae - 8 loi, Arcidae - 8 loi; Cc h cn li c t 1 n 5 loi. Cc ging c s lng loi nhiu gm Tellina - 6 loi, Gafrarium - 5 loi, Arca - 4 loi, Isognomon - 4, Barbatia - 3 loi, Pinna - 3 loi, Pitar - 3 loi, Dosinia - 3 loi, Mactra - 3 loi. cc loi thng gp l Barbatia decussata, Brachydontes curvatus, Isognomon quadragularis, Nuculana taphria, Pinna attenuata, Pinna vexillum, Asaphis dichotoma, Gafrarium pectinatum, G. gibba, Chione squamosa, Ostrea mordax, Ostrea cristagalli, Ostrea glomerata, Chlamys pica, Anomalocardia flexuosa, Meretrix meretrix, Chione (Clausinella) tiara, Chione (Tomoclea) imbricata, Calista chinensis.

- Lp Song kinh v Chn o mi lp ch c 1 h, 2 ging v hai loi.

- Lp chn u l nhm sinh vt kinh t quan trng. Nhng theo kt qu nghin cu trc y ( Cng Thung v nnk, 2002) khu vc Bi T Long v ln cn c 14 loi thuc nhm ny v tp trung ch yu cc h mc nang (Sepiidae) - 6 loi, mc sim (Sepiolidae) - 3 loi, mc ng (Loliginidae) - 2 loi v bch tuc - 3 loi.Kt qu thng k cho thy trong s 197 loi c 149 loi phn b vng triu, bao gm 80 loi c, 59 loi trai bin; vng di triu c 96 loi, 45 loi c v 51 loi trai. C 48 loi phn b chung c vng triu v di triu (25 loi c, 23 loi trai).

Bng 5. Sinh vt lng thn mm vng triu khu vc Ba Mna imcon /m2mg/m2H

Trung bnh i cao triu218.3215291.41.63

Trung bnh i trung triu200.5288935.51.56

Trung bnh i thp triu259.23129600.97

Trung bnh ton vng2152509171.483

- Cc loi in hnh cho vng triu l: Planaxis sulcatus, Nodilittorina granulata, Littorinopsis undulata, Cerithidea cingulata, Cerithium sinensis, Clithon oualaniensis, Nerita allidicilla, N. costata, N. striata, N. yoldi, Monodonta labio, Pateloida spp., Gafrarium pectinatum, G. gibba, G. tumidum.v.v. c bit nhm hu Ostrea glomerata, O. cucullata, O. mordax, O. imbricata, O. echinata pht trin rt mnh, bm chng cht ln nhau, to thnh cc va sinh vt rt in hnh cho bi triu rn . Pht trin mnh trn cc dng bi triu ct v ct bn thuc v h Veneridae. Trong h ny c 27 loi, hay gp l cc loi: Dosinia japonica, D. laminata, Chone isabellina, Anomalodiscus squamosa, Gafrarium pectinatum, G. tumidum, G. divaricatum, Paphia amabilis, P. malabarica, Cyclina sinensis, Meretrix meretrix .v.v.

Hnh 1: Phn b thnh phn loi thn mm khu vc o Ba Mn- S loi phn b vng di triu tp trung chnh l cc loi thuc h c n (Trochidae), c nn (Conidae), c xng (Muricidae). Cc loi thng hay bt gp l: Trochus niloticus, T. maculatus, Turbo coronata, Thais trigona, Thais echinata, Chicoreus bruneus, Ch. torrefactus, Morula maginatra, Conus spp., v.v. Cc loi thuc hai mnh v gm cc nhm loi va sng vng triu v vng di triu, cn c nhng loi ch tm thy vng di triu nh: Amusium sp, Pinna attenuata, P. pectinata, P. muricata, Pteria penguin, Pinctada margaritifera, Pinctada martensii.v.v.

Tim nng ngun li: Thn mm l ngun sng ch yu ca mt b phn dn ngho ven bin. Hng ngy h khai thc c, trai, s mang bn kim tin sinh sng v chi tiu cho gia nh. Gii quyt tt vn s dng hp l ngun li ny s gp phn vo xo i gim ngho cho dn c ven bin.Cu trc ngun li: Trong s gn 200 loi ng vt thn mm pht hin thy Bi T Long th c ti 63 loi thng xuyn c khai thc lm thc phm, xut khu, m ngh v khong 21 loi l danh sch nhng i tng hi sn xut khu ra ngoi nc hoc xut khu ti ch. y l nhng loi sinh vt ng vai tr chnh trong cu thnh ngun li thu sn ngoi c ca nc ta.

- Gip xc: Kt qu phn tch, thng k xc nh c 22 loi thuc 17 ging 10 h phn ln s loi thuc lp ph Gip xc v mm Malacostraca, b Mi chn Decapoda. Trong thnh phn loi thu c, xt cp h, h c s loi nhiu nht l h cua mai vung Grapsidae c 7 loi, sau n h cua Xanthidae c 4 loi; cc h c 2 loi gm h tm he Penaeidae, h tm g m Alpheidae v h cua mt di Ocypodidae, cc h cn li ch c 1 loi. Xt mc ging, ging nhiu nht ch c 3 loi l ging cy lng Sesarma thuc h cua mai vung (Grapsidae). C 3 ging 2 loi l ging tm ro Metapenaeus (thuc h tm He Penaeidae), ging cy ma Metopograpsus (h cua mai vung) v ging cua cm cm Epixanthus (thuc h cua Xanthidae). Cc ging cn li ch c mt loi. Trong s 22 loi trong t kho st 2003-2004, c 5 loi mi c tm thy trong t kho st ny. l mt loi cua u Tritodynamia japonica, 2 loi cua Epixanthus japonicus v Pilumnus minutus, mt loi cua mt di Macrophthalmus japonicus v loi Petrolithes japonicus thuc h orcellanidae. Tuy nhin, trong danh sch ny rt t loi c gi tr kinh t, mc d VQG BTL nm trong vng bin ng Bc c ngun li tm he v cua bi kh ni ting.

Nu tng hp c 2 danh sch iu tra nm 1999 v 2003-04 th c danh mc tng s 40 loi. So vi khu h Gip xc vnh H Long iu tra nm 1998 (73 loi) th Bi T Long nhm ng vt ny th hin s ngho nn r rng, ch bng gn 55% tng s loi chung ca c 2 vng (89 loi). iu ny c th l do din tch vng nghin cu vnh H Long rng hn, c bit l cc kiu mi trng sng phong ph hn.

Trong s 40 loi Gip xc thng k c c mt s loi c gi tr kinh t cao. ng ch hn c c cua xanh, 7 loi gh v 2 loi tm l tm he v tm ro. Trong s ny th nhm gh c sn lng cao nht, thng vn c ng dn nh bt, gom li chuyn v t lin. Cc loi tm nh c khai thc lm thc n cho cc b c. Trong s gip xc pht hin c khng c loi no thuc nhm qu him c ghi vo Sch ca Vit Nam.

-ng vt Da gai: Kt qu thng k cc s liu thu thp c t trc n nay xc nh c 32 loi ca ngnh da gai (bng 6). Trong lp hu bin (Crinoidea) c 1 b, 3 h v 3 loi. Lp hi sm (Holothuroidea) c 3 b 4 h v 8 loi. Lp sao bin (Asteroidea) c 1 b, 2 h v 3 loi. Lp cu gai (Echinoidea) c 3 b, 4 h v 6 loi. Cui cng l lp ui rn (Ophiuroidea) c mt b, 7 h v 12 loi.Trong thnh phn khu h pht hin c, phong ph hn c l lp ui rn, 12 loi, chim 38,7% tng s loi. Tip n l lp hi sm: 8 loi - 25,8%; cu gai: 6 loi - 19,3%, hai h hu bin v sao bin u c 3 loi, cng chim 9,7%.Bng 6: Cu trc thnh phn ng vt da gai o Ba MnLpBHGingLoi

Hu bin (Crinoidea)1333

Hi sm (Holothuroidea)3468

Sao bin (Asteroidea)1334

Cu gai (Echinoidea)3466

ui rn (Ophiuroidea)17812

Cng9202532

So vi cc vng bin gn nh C T mi pht hin c 8 loi v vng H Long - Ct B cng mi ch pht hin c 20 loi, vi khu h Da gai bin Vit Nam ni chung, khong 300 loi (o Tn H, 1994) th ch chim khong 10%. Cn nu so snh vi ton vnh Bc B, khong 70 loi (tng hp cc bo co iu tra ca chng ti) th chng chim khong 45%. Tuy din tch iu tra hn ch nhng do c s a dng v habitat (vng triu , vng triu ct, rn san h v vng ngp nc y mm) nn thnh phn loi ca chng kh phong ph, phn nh ng bn cht ca khu h.

Hnh 2: T l phn trm thnh phn loi ca khu h Da gaiS phn b ca cc loi da gai, ni ring, v ca sinh vt y, ni chung, ph thuc vo nhiu yu t. Nu xt trong phm vi rng (ton cu hay Vit Nam) th cc yu t kh hu (a i) quan trng hn c. Cn trong mt phm vi hp th yu t v c im mi trng sng (habitat) m y l nn y vi cc c im c bn ca chng c vai tr quyt nh. V vy, trong thit k cc im kho st, chng ti quan tm n 3 mi trngchnh: Vng triu, cc rn san h, cc vng ngp nc y bn.

Kt qu nghin cu ngoi hin trng v phn tch trong phng th nghim, thy rng s sai khc v thnh phn loi ca cng mt kiu sinh cnh khng nhiu. S khc nhau v thnh phn loi trong cc sinh cnh khc nhau thng ln hn. Qua kt qu kho st trn thy rng, s phn b ca cc loi Da gai tng t nh cc vng khc, c bit l cc rn san h, trn th gii (Budin, 1980; Levin & o Tn H, 1989; Kalasnikov, 1989; o Tn H, 1991; Lng Vn Kn, 1995). Tng loi hay nhm loi thch ng vi tng loi cht y khc nhau hoc nhng su khc nhau. iu ny c th gii thch bng nhiu yu t nh: ni c tr, phng thc kim mi, cnh tranh ni , thc n... l gii cho mi loi hoc nhm loi cn c nhng nghin cu k hn v sinh thi c th hoc qun th, c bit l nhng loi qu him, c c s bo tn sau ny.

c im ngun li Da gai: Trong cc loi da gai pht hin c VQG Bi T Long, cc loi c gi tr kinh t tp trung vo nhm Hi sm l ch yu. Cc loi Hi sm pht hin c u c th s dng vo nhiu mc ch khc nhau nh lm thc phm, lm thuc. Ngay tn gi "Hi sm" ni ln iu . V vy cn c c bin php qun l thch hp duy tr c ngun li bin cho ny.

Ngoi cc loi hi sm, nhng nm gn y, nhn dn c khai thc trng ca mt s loi cu gai bin nh cu gai en (Diadema setosum) xut khu. y l mt mn thc phm rt b dng mi c quan tm n trong vi nm tr li y.

Mt s loi sao bin nh Archaster typicus cng c khai thc lm m ngh, i khi chng cn c em ngm ru lm thuc. Tuy nhin, gi tr y hc ca chng cn cha c nghin cu y . V vy cn cn thn khi s dng cc loi sinh vt bin trong y dc.

Hin trng ngun li: Tuy thnh phn loi da gai kh phong ph nhng sn lng khng nhiu. Chng ti khng thu thp c cc s liu v hin trng khai thc trong khu vc. Theo thng tin t ng dn a phng cho bit th s khai thc thng do ng dn cc vng khc n, c th do sn lng khng cao nn dn a phng khng t chc khai thc.

2.3. Tnh hnh nghin cu ng vt y o Trn Qung Ninh

o Trn c cc h sinh thi in hnh ca vng bin nhit i, l c thm thc vt kiu rng nhit i, c cc rn san h v c bin kh pht trin, y l ni sinh c quan trng cho khu h ng vt nhit i. Ngoi ra, o cn c cc rn to thnh ni , ni kim mi ca cc loi hi sn thuc tm, cua, c. L mt hn o nh, nhng c nhiu loi cn c bo v c ghi trong sch . V vy ni y s thu ht cc nh khoa hc n nghin cu v ngun gen qu him.

Khu h sinh vt bin s b pht hin c 485 loi thuc 325 ging v 181 h, trong s ny nhm c c s loi nhiu nht vi 157 loi, sau n TVPD c 105 loi, V 98 loi, t nht l rong, c bin mi pht hin 38 loi.

So snh thnh phn loi ca khu h ng vt o Trn vi cc khu h ca cc khu d tr thin nhin bin khc c cng s ln kho st cho thy o Trn c din tch nh hn Ba Mn khong 4 ln, nh hn Ct B 23 ln, nhng thnh phn loi khu h ch km hn Ba Mn 1,5 ln v Ct B 2,7 ln. Ring s loi ca khu h bin, o Trn ch phong ph hn Hn M (440 loi) nhng ngho hn cc o Cn C (493 loi), Ba Mn (561 loi), Thanh Ln (680 loi) v H Mai (756 loi). Chc chn rng s liu ny cha phn nh ht tim nng ngun li gen sinh vt ca o Trn, song nhn chung khu h sinh vt bin ca o Trn cng thuc loi ngho.

Cc rn san h, rn c ph rong m v thm c bin l ni quan trng ca cc loi sinh vt bin. y l ni , ni trng, ni sn mi ca cc loi c, tm v ng vt khng xng sng khc.

2.4. Tnh hnh nghin cu ng vt y Ct B Hi PhngCho n nay hin bit 532 loi ng vt khng xng sng y thuc 270 ging, 115 h, 11 lp ca 4 ngnh: Giun t (Annelida), Chn t (Arthropoda); Thn mm (Mollusca) v Da gai (Echinodermata) ti vng bin Ct B (.C. Thung, 2000, 2003). Trong s ny, Thn mm c s loi phong ph nht - 261 loi, chim 49,1% tng s loi, sau n Giun t - 145 loi- 27,3%, Gip xc - 113 loi, chim 21,2%, Da gai c s loi thp nht vi 13 loi - 2,4% ( Cng Thung, 2001). Cc kt qu nghin cu khu vc vnh Lan H v ln cn, trong hai nm 2003 - 2004 xc nh 311 loi, 210 ging v 105 h V ti y, bng khong 58,4% tng s loi tm thy ti Ct B.

Hnh 3: T l thnh phn loi ca cc nhm hi sn khai thc ch yu ti vng bin Ct B

ng vt y trong h sinh thi y mm v thy vc nc bao quanh: Hin bit 142 loi, 101 ging, 64 h thuc 4 ngnh (xp theo th t ca mc phong ph s loi) nh sau: Ngnh Thn mm (Mollusca) c 62 loi, chim 43,7%. Giun t (Annelida) vi lp Giun nhiu t (Polychaeta) c 33 loi, chim 23,2%. Ngnh Chn t (Arthropoda) vi lp Gip xc (Crustacea) c 37 loi, chim 26,1%. Ngnh da gai (Echinodermata) c 4 loi, chim 2,8%. Sponge: 6 loi, chim 4,2%. Cc loi ng vt y in hnh v c gi tr cao nh Trai ngc (Pinctada martensii), Bn mai (Pinna antenuata, Pinna atropurpurea), c Nn (Trochus maculatus, T. pyramis), h c S (Cypreidae), h Cua bi (Portunidae), h Tm he (Peneidae), Sao bin (Astropecten polycanthus, A. monocanthus), Bt bin (Tethya seychellensis, Biemna cf. Megalosigma,Haliclona subarmigera, Xestospongia cf. estudinaria, Dysidea cinerea).

ng vt y trong h sinh thi san h: 309 loi v bao gm hu ht cc loi qu him trong khu vc nh Tu hi (Lutraria rhychaena), Bn mai qut (Atrina vexillum), c n c, c n ci (Trochus sp) v.v. Mt trung bnh ca V cc sinh cnh khc nhau u cao, trong rn san h t 16,8 con/kg, y mm 271,5 con/m2, vng triu 360 con/m2. Tng t nh vy, khi lng V trong rn 33070 mg/kg, trong y mm 29748 mg/m2 v vng triu 380261 mg/m2. Ch s a dng t 2,2 - 3,6, th hin mt khu vc c mc a dng V cao v s nh hng ca con ngi cha lm suy gim cu trc qun x V. c bit y tp trung nhiu bi c sn v cc bi tp trung mt s loi cha dc liu nh bi Tu Hi (Hang Ti, Ba Tri o, Vn Bi v u B); Bi sao bin (Astropecten polycanthus, A. monocanthus) tp trung Vn Bi - Vn H, Hang C, Hang Sng, Hang Ti; cc bi bt bin cnh xanh (Haliclona spp) ti Ba Tri o, Vn H, Hang Trai v u B.2.5. Tnh hnh nghin cu ng vt y ti Bch Long V Hi Phng

Vn Khng v ctv, 2008 thng k v phn tch v s phn b thnh phn loi ng vt khng sng sng trn h sinh thi o Bch Long V cho chng ta thy thnh phn loi 2 mnh v (Bivalvia) ti y li t hn thnh phn loi lp chn bng (Gatropoda). Lp 2 mnh v c 5 b, 11 h v 15 loi, lp chn bng c 7 b, 12 h v 22 loi. Mt khc, nhm da gai phn b ti y cng c s loi phn b t, ch c 5 b, 7 h v 10 loi. Thnh phn loi phn b ti cc o c th hin trn bng 4.9.

Bng 4.8. Thnh phn loi phn b trn vng rn san h Bch Long V

LpBHLoi

BivalviaPterioidaPteriidaePinctada martensii

Pinctada albina

PinnidaePinna bicolor

Atrina vexillum

ArcoidaArciddaeBarbatia foliata

MytiloidaSeptariidaeSeptifer bilocularis

MytilidaeHormomya mutabilis

OstreoidaOstreidaeSaccostrea cucullata

SponyliaeSpondylus spp

VeneroidaVeneridaeCirce scripta

Grafrarium dispar

Gafrarium pectinatum

CardiidaeCardita lear

ChamidaeChama iostoma

PsammobiidaeAsaphis violascens

GatropodaPatellogastropoda LottidaeNipponacmea fuscoviridis

Nipponacmea gloriosa

NacellidaeCellana enneagona

Cellana toreuma

Cellana testudinaria

VetigastropodaTrochidaeTectus pyramis

Trochus histria

Turbo (lunella) coronoatus coronatus

Turbo (lunella) cornatus coreensis

Turbo stenogyrus

HaliotidaeHaliotis ovina

Haliotis diversicolor

NeritimorphaNeritidaeNerita (Theliostyla) albicilla

Neritina (Dostia) cornucopia

DiscopodaCypraeidaeCypraea (Mauritia) maculifera

Cypraea (Mauritia) arabica asiatica

Cpraea (Erronea) errones errones

Cpraea (Lyncina) vitellus

Cpraea (Erosaria) annulus

Cyraea (Erosaria) moneta

CerithiidaeClypeomorus bifasciata

Cerithium echinatum

NaticidaeNeverita josephinia

NeogastropodaConidaeConus (Darioconus) textile

MuricidaeMancinella echinata

PtenoglossaJanthinidaeRecluzia lutea

BasommatophoraSiphonariidaeSiphonaria (Mestosiphon) atra

Sao binSpinulosidaAcanthasteridaeAcanthaster planci

EchinasteridaeEchinaster luzonicus

ValvatidaOreasteridaeCulcita novaeguineae

Hai SmAspidochirotidaHolothuridaeHolothuria atra

Holothuria leucospilota

StichopodidaeStichopus horrens

Cu GaiAulodontaDiaematidaeEchinothrix calamaris

Echinothrix diadema

Diadema setosum

CamarodontaEchinometridaeEchinostrephus aciculatus

Loi cu gai ch yu ti y l loi cu gai Echinostrephus aciculatus phn b vi mt dy, tuy nhin th phn b mt ca cu gai ti y khng bng mt phn b ti Cn C (124,8-138,5 (nm 2007)) so vi (252,0-547,0 (nm 2008) c th/500m2). Nhn vo gi tr bin thin ca cc ch s nghin cu trn hnh 4.5 chng ta u thy cc gi tr mt ny u tng so vi nm trc, tuy nhin s tng ny ch c tnh cht v s lng m khng mang nhiu v gi tr kinh t, s tng v mt l do tng v s lng cu gai v c n, m gi tr hai loi ny rt thp v c th ni bng khng. Do gi tr kinh t ca loi khng c nn s lng loi khng b nh hng nhiu ca p lc khai thc, m ch yu l do nh hng gin tip t vic khai thc cc loi hi sn khc nh s ph hoi mi trng v sinh thi loi. Theo nhng nh gi bc u trong cng cuc khai thc bn vng v bo v loi bo ng chn l (Haliotis diversicolor) l 1 loi ng vt y c gi tr kinh t cao ti o Bch Long V ang c nhng du hiu kh quan v mt v cht lng phn b ca loi bo ng ti y. Nhng du hiu kh quan trong vic bo v loi t vic tin hnh ph bin cc chnh sch, php lut, gio dc ngi dn hiu v thc hin tt cc ch trng v bo v v khai thc bn vng ngun li hi sn l c s quan trng trong vic thit lp cc khu vc cn bo v nng cao cht lng cc loi ng vt y c gi tr kinh t cao ni ring v ngun li hi sn ni chung

2.6. Tnh hnh nghin cu ng vt y Hn M Thanh Ha

Vng bin qun o Hn M thuc huyn Tnh Gia, nm pha nam ca tnh Thanh Ha, gip vi huyn Qunh Lu ca tnh Ngh An. y l mt qun o ln ca vng bin ven b Bc Trung B, ng vai tr rt quan trng v an ninh, quc phng, kinh t v sinh thi khu vc. Vng bin quanh o Hn M t xa ni ting l mt ng trng tt vo bc nht ca vnh bc b xt v sn lng nh bt, phm cht c v thi gian khai thc trong nm. Ng trng ny chc chn c lin quan cht ch vi s c mt ca qun o hn M v chnh a th qun o vi s c mt ca h sinh thi san h ng vai tr gi ging, bo v ngun gen cho khu vc.

Qun o Hn M c v tr to 1922' - 1923' N, 10555' - 10556' E, thuc huyn Tnh Gia, nm pha nam tnh Thanh Ha v cch t lin 11km. Tng din tch ca qun o (phn o) ny vo khong 450ha, trong o Hn M c din tch ln nht (420ha) v hn 10 o nh (din tch khong 30ha). Khu vc ny c kh hu nhit i gi ma v chu nh hng ca 2 ma gi trong nm l gi ma ng bc v gi ma ng nam. Trn o hin nay cha c dn nh c, ch c n v b i ng qun. Tuy nhin, do nm kh gn t lin nn hot ng khai thc hi sn y rt nhn nhp, nht l vo ma khai thc.

Qun o Hn M l khu vc nh bt c quan trng Vnh Bc B, l ni kim sng ca cc cng ng dn c huyn Tnh Gia v cc tnh ln cn. Trong khu vc c mt s lng cc loi c c gi tr kinh t cao nh tm hm, bo ng, trai ngc, hi sm v mt s loi rong bin. Theo kt qu iu tra trc y ca Vin Ti nguyn v Mi trng bin, khu vc quanh o Hn M c khong 440 loi sinh vt bin thuc 165 ging bao gm 133 loi thc vt ph du, 46 loi ng vt ph du, 8 loi rong bin, 56 loi san h, 141 loi ng vt y v 55 loi c san h. Tuy san h c s loi khng cao song chng c coi l ci ni ca cho cc loi sinh vt bin c tr, c bit l cc loi c, trai, c (l cc i tng khai thc chnh ca ng dn). Do cc hot ng khai thc hu dit cng vi s nhim mi trng t cc hot ng ven b gy ra, cc rn san h y ang b suy thoi nghim trng, nhiu ni ch cn li nhm san h dng khi v c ph khng cao, bnh qun di 30%.

H sinh thi vng triu rn : y l loi h sinh thi rt quan trng qun o Hn M. Vng triu chim hu ht din tch ven o, l ni c tr ca rt nhiu loi sinh vt ven b, c bit nhm c, hu, gip xc nh v rong bin, vng cn triu thng c bo ng tm hm trong hang hc. Vo thng 4 5 khi rong bin pht trin cc thnh, cc thm rong m ph kn vng triu v cn triu. Xt v tnh a dng sinh hc th vng triu l mt trong nhng sinh cnh c s a dng cao nht, c bit l vng triu rn .

H sinh thi cc bi ct ct bn: ven bn o Nghi Sn l cc bi ct mn p v cc bi ct bn rng hng trm ha. Cc bi ct mn p c gi tr du lch sinh thi cao. Cc bi bn, ct ven bn o c nhiu loi sinh vt sinh sng, to thnh cc bi c sn nh bi s huyt (Anadara granosa), bi s lng (Anadara antiquata), bi ngao du (Meretrix meretrix) .v.v. y l khu vc gip cho ngi dn ngho, t vn hng ngy khai thc khi triu rt, m bo cuc sng hng ngy ca gia nh h.

H sinh thi san h: L loi h sinh thi quan trng nht ca bin nhit i. H sinh thi rn san h c nng sut sinh hc v tnh a dng thuc loi cao nht hnh tinh, c v p quyn r nn c tim nng to ln cho kinh t du lch. Rn san h chng nhng cung cp cho ngi dn ven b nhiu sn phm c gi tr kinh t cao m cn c gi tr ln trong vic bo tn ngun ging ven b, to ra ngun vt cht hu c giu c cung cp cho chui thc n ca vng bin ven b. Vng qun o Hn M c 36 loi san h to rn phn b, nhiu ch chng pht trin tp trung thnh rn kiu patch reef. Trc nm 1993 san h o Hn M pht trin kh tt, k c nhm san h dng cnh l Acropora. Sau 4 nm kho st lp li thy rn san h y ang b suy thoi nghim trng. Nguyn nhn ca qu trnh suy thoi ny c th c nhiu, song r nht l hot ng n mn. Ngoi ra c th l do hot ng khai thc ca ngh cu c rn.

a dng sinh hc bin c kho st kh chi tit 1 t vo thng 10/1997 do Vin Ti nguyn v Mi trng bin thc hin vi chuyn mn l thc vt ph du, ng vt ph du, rong bin, san h, ng vt y (thn mm, gip xc, giun t v da gai), c san h. Trong s cc nhm sinh vt kho st th ng vt y c s loi nhiu nht (141 loi, chim 32,3%); sau ln lt ti thc vt ph du (133 loi, 20%); san h (56 loi, 12,7%); c san h nhm sng khng ri cc rn (55 loi, 12,5%); ng vt ph du (46 loi, 10,5%); t nht l rong bin ch c 8 loi (1,8%) do kho st vo thng rong b tn li.

Trong s 141 loi ng vt y thuc 102 ging, 66 h ca 4 nhm ng vt y chnh, bao gm:

- Ngnh giun t (Annelida) c lp giun nhiu t (polychaeta) c 19 loi, 14 ging, 11 h.

- Ngnh chn t (Arthropoda) c lp gip xc (crustacea), c 19 loi, 18 ging, 11 h.

- Ngnh thn mm (Mollusca) c 95 loi, 61 ging, 36 h.

- Ngnh da gai (Echinodermata) c 8 loi, 8 ging, 7 h.

Ngoi s phong ph v a dng ngun gen, khu h sinh vt y y cn c nhiu loi sinh vt qu him c nguy c b tuyt chng cn c quan tm nghin cu bo v. Qua kt qu phn tch, thng k c 5 loi thn mm c trong Sch Vit Nam, l:

- Bo ng hnh bu dc Haliotis ovina.

- c n c Tectus pyramis.

- c x c Turbo marmoratus.

- Trai ngc mi vng Pinctada margaritifera.

- St Anomalocardia squamosa.

Ngoi 5 loi thng k trn, nhiu loi qu him khc cng c kh nng phn b vng bin ny nh c hng babylonia, c nhy li Strombus luhuanus, tm hm Panulirus, theo ng dn a phng l c mt quanh o nhng do chng ti khng thu c mu nn khng a vo danh mc.

Trong t kho st thng thng 4/2009 cc loi thn mm qu him ch cn pht hin c hai loi gm:

- Loi bn mai qut Pinna atrina

- Loi trai ngc mi vng Pinctada margaritifera

Hai loi c n c v c x c khng cn thy trn cc rn san h. Tuy vy cng lu l ti y c bi c mc ln phn b xung quanh o Hn M v cc bi hu phn b ven chn cc o. y l dng ngun li quan trng, gip nhng ngi dn a phng kim sng hng ngy. Ti y, chng ti cn pht hin mt s loi ng vt y c gi tr dc liu nh loi nhm bin (Diaderma setosum) hoc mt s loi san h mm thuc nhm Lobophytum v Sarcophyton

Nh vy, cc kt qu nghin cu trong t ny v ng vt y, xc nh cc loi qu him trc y, hin nay cn li rt t. c bit mt s loi c gi tr kinh t nh bo ng th gn nh khng thy xut hin. Xt cu trc thnh phn loi V ca vng bin xung quanh o Hn M cho thy: thn mm c thnh phn loi phong ph nht, chim 67,3% tng s loi, giun nhiu t v gip xc c s loi tng ng ng th 2, chim 13,5% tng s loi, da gai chim t l s loi thp nht, ch c 5,7%.

Xt n taxon bc ging cho thy, trong giun nhiu t c 1 ging t s loi cao nht, 3 loi, 3 ging khc, mi ging c 2 loi, s cn li mi ging c 1 loi.

Cn c vo s hin din ca cc loi, vo phng thc sng ca chng vng bin xung quanh qun o Hn M cho thy: V ti y bao gm cc i din ca 2 qun x c bn: qun x y cng (hard bottom) sng trn nn y , phn b t vng triu xung vng di triu v qun x y mm (soft bottom) thuc nn y ct t bn vng di triu.

Ngoi ra, cng d dng nhn thy tuyt i a s cc loi u l cc i din sng bin c mui cao v n nh. iu ny hon ton ph hp vi v th ca o, nm tng i xa t lin (khong 15km), xa cc ca sng.

c im sinh vt lng: vng bin xung quanh qun o Hn M cc nhm V chim cc th hng khc nhau trong thnh phn sinh vt lng. vng di triu (y mm), giun nhiu t, t sinh vt lng bnh qun cao nht (46 con, 1,24g/m2), sau n gip xc (17 con, 0,65g/m2) v thn mm (18 con, 0,52 g/m2). Da gai c sinh vt lng bnh qun thp nht, ch t 3 con, 0,14g/m2. Tri li trn vng triu y cng, thn mm li c sinh vt lng bnh qun cao nht, t 213 con, 13,8 g/m2 sau n giun nhiu t (150 con, 2,54 g/m2) v gip xc thp nht (88 con, 2,6 g/m2).

Phn b ca V: Hn M v cc o ln cn nh Hn t, Hn Vng, Hn Ming, Hn Bng v c bn u l cc o . Do s xm thc mnh ca sng bin nn xung quanh o u c cc bi tng ln vi vch dc t 40 50o (Vng Nh n, Hn Ming). Ch gp bi tng, cc c va xen ln si sn vi dc thoai thoi Hn Bng v bn o Nghi Sn. Ngoi ra cng ch thy mt bi triu ct khng ln bn cnh cu cng ca n v b i bo v o Hn M.

- Khu cao triu: Khu ny dng nh dnh cho cc loi c kh nng chu hn tt nh c ch gi nc ca c th. Thuc v nhm ny c cc loi Chthamalus sp. Mitella mitella sng bm c nh trn cc tng hoc cc khe . ng ch , cc loi c nh thuc h Littorinidae li c kh nng chu hn cao hn. Chng c th b qua khi vng triu ln ti vng trn triu ca cc vch . Ngoi ra, khu cao triu cn c nhng loi hu (Ostrea spp) c kh nng phn b ti na trn ca khu trung triu, hoc cc loi cua Grapsus trnuicrustatus, Metopograpsus quadridentatus, c kh nng vn ng nhanh kim mi trn c khu cao v trung triu. Mt s loi khc phn b hp hn, ch khu cao triu (Sesarma bidens) hoc ranh gii khu cao-trung triu (Nerita albicilla).

- Khu trung triu: Bao gm cc loi c kh nng phn b rng trn c hai khu trung cao triu hoc trung thp triu.

- Khu thp triu: Bao gm cc loi chu s ngp nc thng xuyn hn. Hu ht cc loi sng bm c nh vo cc khe nh cc chn t to thnh cc qun th hoc cc m nh. Cc i din in hnh: Mytilus edulis, Pinctada margaritifera, Isognomum legumen, Pinna spp.

Tim nng ngun li ng vt y:

- Tim nng ngun gen: Vi 141 loi ng vt y pht hin c, ta thy tim nng ngun gen ca sinh vt y ca vng bin quanh cc o ca qun o Hn M rt phong ph, a dng, c bit l thn mm vi 95 loi. Tuy nhin, kt qu cn nhiu hn ch do khng c kh nng t chc kho st bng li vt cc vng bin xa b xung quanh qun o ny, v vy trong danh mc cn vng mt nhiu loi gip xc v thn mm c gi tr (v d c hng Babylonia).

- Cc loi c gi tr kinh t: Xt v mt kinh t, ng vt y c th chia ra cc nhm khc nhau, ng ch hn c l gi tr thc phm, gi tr thng mi nh lm m ngh hay nui ly ngc...

- V gi tr thc phm: ng ch hn c l cc loi thuc b gip xc mi chn (Decapoda), cc loi c nh bo ng Haliotis ovina, c n Tectus pyramis, Trochus maculatus, c a Nerita albicilla, c hng Babylonia areolata, cc loi trai nh s Anadara antiquata, vm xanh Myrilus viridis, bn mai Pinna spp., hu Ostrea spp., mt s loi thuc lp bin mang (Eulamellibranchia). Chng l nhng i tng thng c ng dn khai thc b xung cho ba n hng ngy thay cho cc loi thc phm giu cht m khc nh tht, trng...

- V gi tr thng mi: ngoi gi tr thc phm thng thng, mt s loi c coi l c sn do c gi tr thc phm cao nh bo ng (Haliotis ovina), tm hm (Palinurus), s (Anadara antiquata), c hng (Babylonia areolata) nn chng v l nhng i tng c khai thc, nui v xut khu. Nhiu loi cn c gi tr lm m ngh nh khm x c nh bo ng, vm, trai ngc, c n... V vy chng l nhng i tng khai thc, thu mua ca cc c s lm m ngh. Mt s loi khc cn c gi tr m ngh trc tip nh hnh th k d, c o nh c n Trochus, c x c Turbo, c bng Cypraea, c gai Muricidae, c t v Hemifusus tuba... bn cho khch du lch trong nc v quc t.

2.7. Tnh hnh nghin cu ng vt y Hn Mt Ngh An

Cho n nay cha c cng trnh nghin cu tng hp v ng vt y ti khu vc o Hn Mt Ngh An.2.8. Tnh hnh nghin cu ng vt y Hn La Qung Bnh

Tnh c b bin di 116,04 km pha ng vi 5 ca sng, trong c hai ca sng ln, c cng Nht L, cng Gianh, cng Hn La, Vnh Hn La c din tch mt nc 4 km2, c su trn 15 mt v xung quanh c cc o che chn: Hn La, Hn C, Hn Cha c th cho php tu 3-5 vn tn vo cng m khng cn no vt. Trn t lin c din tch kh rng (trn 400 ha) thun li cho vic xy dng khu cng nghip gn vi cng bin nc su

Qung Bnh c vng thm lc a v vng c quyn kinh t rng trn 2 vn km. Ngoi khi li c cc o Hn La, Hn Gi, Hn Nm, Hn C, Hn Cha nn hnh thnh cc ng trng vi tr lng 10 vn tn hi sn cc loi.

Cho n nay cha c cng trnh nghin cu cp n ngun li cng nh c trng v sinh vt y vng bin quanh o Hn La.2.9. Tnh hnh nghin cu ng vt y Cn C - Qung Tr Vn Khng v ctv, 2008 xc nh c thnh phn loi phn b ca lp cu gai, hi sm, sao bin ca nhm da gai ti Cn C gm c 5 b, 8 h v 14 loi (bng 7).

Bng 7: Thnh phn loi phn b ca lp sao bin, hi sm, cu gai trn vng rn san h Cn C

LpBHLoi

Sao binSpinulosidaAcanthasteridaeAcanthaster planci

EchinasteridaeEchinaster luzonicus

ValvatidaOreasteridaeCulcita novaeguineae

OphidiasteridaeLinckia laevigata

Linckia multifora

Hai SmAspidochirotidaHolothuridaeHolothuroidea

Holothuria atra

Holothuria edulis

Holothuria hilla

Holothuria impatiens

StichopodidaeStichopus chloronotus

Cu GaiAulodontaDiaematidaeEchinothrix calamaris

Echinothrix diadema

CamarodontaEchinometridae

Phn b thnh phn loi ca nhm nhuyn th c th hin trn bng 8. Thnh phn ca nhm nhuyn th bao gm 2 lp, 5 b, 9 h v 17 loi.Bng 8: Thnh phn phn b nhuyn th trn vng rn san h ti Cn C

LpBHLoi

BivalviaOstreoidaGryphaeidaeHyotissa imbricata

OstreidaeOstrea circumpicta

PterioidaIsognomonidaeIsognomom isognomum

PinnidaePinna bicolor

Atrina vexillum

Pinna albina

PteriidaePinctada margaritifera

Pinctada sp

Pinctada fucata martensii

Peria breviata

GastropodaVetigastropodaTrochidaeTectus pyramis

Trochus maculatus form vevoucocus

Trochus maculatus

NeogastropodaTurbinellidaeAstralium okamotoi

Turbo chrysostomus

MuricidaeChicoreus (Triplix) brumeus

DiscopodaCypraeidaeCypraea sp

Cn C c v tr quan trng, l ni tip gip gia hai vng bin Vnh Bc b v vng bin min Trung. Cng nh mt nhm ng vt y khng xng sng vng rn ti Ph Quc, mt ng vt y ti cng ph thuc ch yu vo mt cu gai en. Tuy nhin th mt cu gai en ti hai o ny c s khc bit, Cu gai en ti Ph quc l loi cu gai Diadema setosum l loi c kch thc to, gai di, c kh nng lm thc n cho con ngi (trng trong ma sinh sn ca loi ny c gi tr dinh dng rt cao v c mt s thc khch rt u chung). Cn ti Cn C l loi cu gai Echinostrephus aciculatus, y l loi cu gai en nh, gai ngn v thng sng trong l v cha c khai thc do khng c gi tr kinh t. Hnh nh hai loi cu gai ny c chng ti th hin trn hnh 4.

Hnh 4: Cu gai en Diadema setosum ti Ph Quc v Echinostrephus aciculatus ti Cn C

Gi tr bin thin ca nhm ng vt y ti h sinh thi rn san h Cn C vi cc ch tiu nghin cu c nhm nghin cu chng ti th hin trn hnh 5.

Hnh 5: Biu bin ng mt nhm ng vt khng xng sng Cn C

Qua biu bin ng mt ng vt y ti Cn C v gi tr trung bnh nm cho thy, cc ch s ca cc nhm loi u gim so vi nm trc. Trong cc ch tiu nghin cu trn th gi tr hi sm ti y cho thy nhng iu bi quan nht, bi hi sm phn b ti y c nhng loi gi tr kinh t cao v phn b vi mt nhiu nh loi hi sm Stichopus chloronotus cn xut hin trn mt ct kho st. Sau 2 nm nghin cu mt phn b hi sm dao ng t 7,727 xung cn 0,5 con/500m2, ti y c loi hi sm Stichopus chloronotus c gi tr trn th trng v c ng dn khai thc nhiu v nht l ng dn khai thc bng ngh ln. Ti Cn C khng ch c ng dn trong tnh Qung Tr khai thc m cn c cc ng dn ti cc vng ln cn nh Qung Bnh, Qung Ngi... cng tham gia khai thc, sau khi khai thc phn ln chng c bn cho cc thuyn thu mua trn bin, mt phn c mang ln o phi kh. T nhng s liu thc t cho chng ta thy rng s suy gim ngun li ng vt y ti y ang mc bo ng nu nh chng ta khng c nhng quy hoch trong vic bo v loi v h sinh thi loi ti ni y.

2.10. Tnh hnh nghin cu ng vt y Sn Tr Hi Vn

Vng bin ca o Sn Tr v ni o Hi Vn nm pha nam ca tnh Tha Thin Hu, ni c coi l vng ca ca vnh Bc B, c iu kin t nhin v hi dng sinh vt c o, chu nh hng chi phi ca c vnh Bc B v bin ngoi. Cc cuc iu tra kho st v a dng sinh hc bin cho ti nay vng ny tuy cn rt t, song u nh gi rng vng ny c a dng sinh hc kh cao, c bit c h sinh thi san h pht trin kh tt ngay b lc a l o Hi Vn. Cng vi cc h sinh thi giu tim nng trn t liu l Vn Quc Gia Bch M, cc h sinh thi bin c th Hi Vn-Sn Tr ng vai tr rt quan trng v sinh thi v ti nguyn cho vng trung b ca nc ta.

pht hin c 110 loi ng vt y c ln trong :

- Ngnh giun t Annelida c 9 loi chim 8,18%.

- Ngnh chn t Arthropoda c 20 loi chim 18,18%

- Ngnh thn mm nhiu loi nht c 65 loi chim 59,09%.

- Ngnh da gai Echinodermata c 15 loi chim 13,64%.

- Ngnh hi min Spongia c 1 loi chim 0,91%.

Nhn chung thnh phn loi ng vt y pht hin cha nhiu do iu tra cn t, nhng li c nhiu loi c gi tr kinh t cao nh tm hm Panulirus spp. (c 2 loi), bo ng haliotis ovina, c n Trochus niloticus, Tectus pyramis, trai ngc mi en Pinctada margaritifera, c bn tay Lambis lambis, c bng Cypraea spp., c t v Cymatium, c ci conus, bn mai pinna, cc loi hi sm holothuria (4 loi).

S phn b ca ng vt y trn cc sinh cnh theo su th hin s phn i r:

- Vng triu khu vc kho st tng i nh hp do tnh cht thy triu bn nht triu c bin nh. C 2 loi sinh cnh bi l bi v bi ct. Sinh vt y phn b tp trung ng c trn bi triu , mt ti 100 500 con/m3. Trong thnh phn nh lng u th thuc v thn mm. vng triu ct c sinh vt ngho nn hn nhiu, nhm u th l cua v hai mnh v.

- Sinh vt y vng di triu phong ph hn v thnh phn loi do c sinh cnh a dng, mi trng sng thun li nh c rn san h, thm c bin v cc rn c nhiu thc n v ni tr n. Cc nghin cu sinh vt lng ng vt y sng trong rn san h cht cho cc gi tr ln rt ng ch , y l ngun thc n phong ph cho c v cc loi gip xc ln sng trong rn v ln cn.

Bng 9: Sinh vt lng ng vt y khu vc o Sn TrSinh vt lngT l %

Con/kg ymg/kg yMt Khi lng

Giun t1,7166,516,253,81

Gip xc1,366,712,501,41

Hi min-402,7-8,49

Thn mm7,14098,668,2786,45

Da gai0,36,52,880,14

Tng cng10,44741,0100100

Cng nh nhiu vng khc ven b bin nc ta, sinh vt y lun lun l i tng c khai thc thng xuyn, lin tc ca cc cng ng c dn ven bin. Cc loi ng vt y kinh t vng bin ny cng ang c khai thc rt mnh tiu dng v xut khu, tp trung nht vo tm hm v trai c, sau l hi sm. Tm hm nh cn c nui gi trong lng ti khi t kch thc xut khu. V vy, ngun li t nhin trong vng cng b suy kit do khai thc qu mc, nhiu loi ang trong tnh trng tuyt ging nu khng c bin php bo v kp thi.2.11. Tnh hnh nghin cu ng vt y C Lao Chm Qung Nam

- Gip xc: T trc n nay cc nghin cu khng ch trng my ti nhm ng vt ny. C 4 loi tm hm: Panulirus longipes, P. omatus, P. stimpsoni v P. versicolor v 1 loi cua Charybdis feriata c tm thy trn cc rn san h thuc C Lao Chm. y l nhng loi kinh t quan trng i vi ng dn a phng. Trong tm hm ornate c xem l loi quan trng v nhu cu lm thc phm v nui trng thy sn.

- ng vt da gai: Khong 16 loi thuc 9 ging v 8 h da gai c ghi nhn ti C Lao Chm. Diadema setosum, Acanthaster planci, Holothuria edulis v Holothuria atra l nhng loi ph bin ti hu ht cc rn sa h. Sao bin gai Acanthaster planci v nhm bin Diadema c ghi nhn l c s lng ln trn mt s rn.

- Mt ca cc loi chim u th xt theo tm quan trng v ti nguyn v sinh thi nhn chung c ghi nhn l tng i thp. Pinctada margaritifera l loi ng c nht ti tt c cc rn, vi mt trung bnh l 4,4 (s.e = 0,7) c th 400m2 (t 1,0 - 10), Pinana bicolor c t 1-16 c th 400m2, ch gi trung bnh l 4,3. Mt loi Atrina vexillum c t 0,5-6 c th 400m-2. Tridacna squamosa c tm thy hu ht cc im kho st, vi mt trung bnh l 1,3 c th 400m-2 v con s ny cao hn so vi s lng loi ny hu ht cc vng duyn hi khc Vit Nam. Bo ng haliotis spp. v top shell vng bng hoc rt him tt c cc im kho st. Mt trung bnh ca Testus pyramis di 1 c th 400m-2 trong khi haliotis spp. ch c ghi nhn nh mt loi ti mt vi im. Cc cuc kho st v cht lng ti nguyn ti Bi Da Ban v Vng Cay Chanh (ng C Lao Chm) ghi nhn c mt s c th loi Haliotis ovina v Haliotis varia trong khi Testus pyramis c tm thy vi s lng nhiu, hu ht l kch nh.

- Tm hm, gm c Parulirus longipes, P. ornatus, P. stimpsoni v P. versicolor tr ln ph bin vng bin C Lao Chm. Cc d liu thu thp c ti 15 im kho st cho thy mt tm hm thp, trung bnh l 1,1 c th 400m-2 c tm thy ti mt s kho st (Hn Co, Vung Ran, Hn Gii, Bi Bc, Hn Tai). Tm san h Stenopus hispidus vng bng tt c cc a im. Cc tm hm trng thnh v post settled c khai thc lm thc n v nui v v vy nn ang tin hnh mc b khai thc cn kit trong khu vc.

- Mt ca cc loi ng vt da gai ch th, bao gm sao bin gai, nhm bin v hi sm c ghi nhn tng i thp. Acanthaster planci c tm thy tt c cc im kho st. Mt trung bnh l 2,4 c th 400m-2 vi s lng nhiu nht tm thy vng Da Den Bc Hn Tai v Vng Rang Bc Hn L. Nhm bin Diadema setosum xut hin vi s lng kh thp, t 3,5 79 c th 400m-2, trong Sung Ben Ty bc Hn Gii, Vng Rang Bc Hn L, Vng Nhan ng C Lao Chm, Vng Cay Chanh Ty Hn M v nam Hn Co cung cp s lng nhiu nht, t nht l 44 c th. Loi hi sm n c vng bng hu ht cc rn trong khi cc loi khng n c Holothuria edulis v Holothuria atra xut hin vi s lng kh nhiu nam Hn Co, Vng Ben Lang, ng Bc Hn Gii v Vng Cay Chanh Ty Hn M.

- Ni chung, cc a im c nhiu loi v mt cao cc sinh vt ln tng y, t s lng ca Acanthaster planci l ch yu xung quanh hn M, Hn Gii, Bi Du Tai v Bi Bc hn l cc khu vc khc. Nhng khu vc ny cung cp s lng nhiu cc ngun ti nguyn chim u th hn nh l ng vt thn mm, tm hm v hi sm hn cc khu vc khc.

2.12. Tnh hnh nghin cu ng vt y L Sn Qung Ngi

Hi tho nhm iu tra nh gi hin trng cc h sinh thi, xy dng cc lun c khoa hc xut d n khu bo tn bin o L Sn. Theo PGS- TS V Thanh Ca - Ph vin trng Vin Nghin cu qun l bin v hi o (Tng cc Bin v Hi o VN), nc ta cc h sinh thi v a dng sinh hc bin ng gp rt ln vo vic pht trin kinh t - x hi thng qua bo m an ninh lng thc, duy tr ngun gen v cung cp nguyn liu sn xut nhiu loi thuc. Ring ti vng bin o L Sn, rn san h v c bin l hai kiu h sinh thi c trng vi rt nhiu loi hi sn c gi tr kinh t cao v mt s loi qu him nh san h xanh, san h en, bo ng, trai tai tng. Tuy nhin, qua 2 t kho st ca Vin Nghin cu qun l bin v hi o cho thy h sinh thi bin o L Sn b suy gim nghim trng.

S a dng ca h sinh thi vng bin v h sinh thi o L Sn l ngun ti nguyn thin nhin v cng qu gi, nhng rt nhy cm, d b bin ng v suy thoi. Do vy, khai thc hiu qu nhng tim nng y phc v pht trin du lch trn o L Sn i hi phi da trn nhng cn c khoa hc, pht trin du lch phi gn vi bo tn, nng cao i sng v nhn thc ca nhn dn. c bit, vic tuyn truyn, nng cao nhn thc ca ngi dn trong bo v h sinh thi bin, chng cc hnh thc nh bt cn kit, mang tnh hy dit song hnh vi quy hoch pht trin kinh t, x hi hp l, o to, chuyn i ngh nghip, xa i gim ngho, nng cao mc sng ngi dn c tm quan trng c bit.

H sinh thi rn san h bin L Sn c tng s 107 loi san h cng phn b (Latypov, 1995 v V S Tun 2003) v c nh gi l c din tch ln nht (1.704 ha) so vi din tch cc vng rn trn 10 vng bin khc (vng bin C T 369,8 ha; Bch Long V 1.578 ha; Cn C 274 ha; C Lao Chm 116 ha; Vnh Nha Trang 731 ha; Ph Qu 1488 ha; Nam Yt 250 ha; Cn o 903 ha v Ph Quc 220 ha) ( Vn Khng v ctv, 2008). Nhng nhm loi sinh vt phn b trong h sinh thi rn vng bin ny rt a dng; nh c rn 98 loi (Li Duy Phng v ctv, 2008), thn mm 47 loi (Nguyn Huy Yt v ctv, 2001), da gai 27 loi, gip xc 39 loi ( Cng Thung, 2001), thc vt ph du 168 loi, 79 loi/nhm loi ng vt ph du (Nguyn Dng Tho, 2001). . Trong c nhiu loi hi sn qu him, c gi tr kinh t cao nh tm hm, gh, hi sm, vm xanh, ip, c thu, c m, cua bin, mc... Thm rong - c bin trong vng bin ny c nh gi l c din tch v tr lng tng i ln. Cc kt qu nghin cu ca Nguyn Hu i & Phm Hu Tr (2006) xc nh c 161 loi rong - c bin phn b vng bin L Sn. Trong thnh phn rong bin o L Sn, c khong 20 loi c gi tr kinh t c tr lng c tnh gn 1.000 tn ti/nm. H sinh thi rong - c bin L Sn c vai tr quan trng trong hot ng iu chnh, n nh mi trng sng, to ngun thc n, ni c tr l tng cho nhiu loi sinh vt bin c gi tr kinh t, khoa hc (nh ra bin, c nga, hi sm, tm , cua, c, ng vt y, thn mm...).

Tuy nhin, theo kt qu nghin cu ca Vin Nghin cu Hi sn (2005-2007), do nh hng ca cc hot ng pht trin kinh t - x hi, khai thc qu mc ngun li, cc tc ng tiu cc ln mi trng vng gn b dn n cc h sinh thi in hnh nh san h, vng triu ti L Sn ang c xu hng b thu hp din tch, ph v cht lng ca cc h sinh thi cng ang c chiu hng suy thoi, a dng sinh hc b gim st trong nhng nm gn y. Nhiu loi qu him, c hu hoc c gi tr kinh t cao ang dn b suy gim. Vi mc ch bo tn, pht trin v s dng hp l ngun ti nguyn bin, vic thnh lp Khu bo tn bin o L Sn l rt cn thit, c ngha thc tin v khoa hc cao.

Tim nng bo tn bin: Qua tm hiu v tng hp s lc cc kt qu nghin cu t trc ti nay cho thy khu vc bin o L Sn l khu vc c c nhiu tim nng bo tn nh: cc iu kin t nhin ca vng bn thun li cho sinh vt pht trin ( mui tng i cao, cht lng nc cha b nhim, cht y ch yu l gc, ct thun li cho rn san h v thm rong - c bin pht trin). Tnh a dng sinh hc cao, c gi tr kinh t, khoa. L khu vc cung cp ngun ging cho vng bin ln cn, m bo nng sut sinh hc cho vng nc quanh o. Nhng do nhiu l do khc nhau, a dng sinh hc, ngun li sinh vt ang ngy cng c xu hng b suy gim. V vy, yu cu v bo tn, hay ni cch khc l tim nng bo tn khu vc l rt cao. Vic quy hoch vng ny thnh khu bo tn bin vi cc chc nng nhim v r rng cn phi nhanh chng c hon thin. 2.13. Tnh hnh nghin cu ng vt y khu vc vnh Nha Trang

Oyvind Fjukmoen, 2006, nghin cu v khu h ng vt y khu bo tn Hn Mum, y l cng trnh nghin cu mi nht v ng vt y c ln ti khu bo tn bin Vit Nam. Mt nghin cu m c phng php nghin cu ging vi chng ta nht tuy nhin th nghin cu ny li khng nm trong cc vng m chng ta tp trung nghin cu. Nghin cu a ra kt qu v khu h ng vt y ti khu bo tn bin Hn Mun c trnh by di bng 10.Bng 10: Thnh phn loi nhm ng vt da gai phn b ti Hn Mun-Nha Trang Hu bin (Crinoidea)12345678910

Himerometridae

Himerometra robustipinna (Carpenter, 1881)+++++++.+..+.

Mariametridae

Stephanometra sp. x.........

Colobometridae

Cenometra bella ( Hartlaub, 1890)+++x....x.

Comasteridae

Comanthus parvicirrus (Muller, 1841)+++.x...+.

Comaster sp.+.........

Phanogenia sp. +.........

Oxycomanthus bennetti (Muller, 1841)+++++..++..+.

Sao bin (Asteroidea)

Acanthasteridae

Acanthaster planci (Linnaeus, 1758)+++++x++x..x.

Ophidiasteridae

Linckia laevigata (Linnaeus, 1758)+++++x++x.x+.

Nardoa frianti Koehler, 1910.x........

Pterasteridae

Euretaster insignis (Slade, 1882)x.........

Oreasteridae

Choriaster granulatus Lutken, 1869x...+.....

Culcita novaeguineae Muller & Troschel, 1842+++..++....

Protoreaster nodosus (Linnaeus, 1758)........x.

Astropectinidae

Astropecten monacanthus Sladen, 1883x..+......

Astropecten sp.x.....x...

i rn (Ophiuroidea)

Ophiotrichidae

Macrophiothrix sp.xx........

Ophiocomidae

Ophiocoma scolopendrina (Lamarck, 1816).......x.x

Ophiomastix annulosa (Lamarck, 1816)xx........

Cu gai (ECHINOIDEA)

Diadematidae

Diadema savignyi Michelin, 1845+++x++..+.

Diadema setosum (Leske, 1778)+++++++++++++++.x++.

Echinothrix calamaris (Pallas, 1774)+++++x..x.

Echinohtrix diadema (Linnaeus, 1758)x.x.xx....

Toxopneustidae

Toxopneustes pileolus (Lamarck, 1816)+...+++..+.

Tripneustes gratilla (Linnaeus, 1758).........

Clypeasteridae

Clypeaster sp........x..

Loveniidae

Lovenia elongata (Gray, 1845)x.........

Hi Sm (HOLOTHUROIDEA)

Actinopyga sp.x........

Holothuria (Mertensiothuria) leucospilota (Brandt, 1835).....x...

Pearsonothuria graeffei (Semper, 1868)+xx..x....

Stichopodidae

Stichopus chloronotus Brandt, 1835+x.....x..

Thelenota ananas (Jaeger, 1833).....x...

Synaptidae

Synapta maculata (Chamisso & Eysenhardt, 1821)+.++++......

Synaptidae indet.+.++......

Dendrochirotida sp...+++...x

Ngun: (Oyvind Fjukmoen, 2006)Ghi ch: X: Quan st mt ln:

++: 6-30 c th/400m2

+++: Trn 30 c th/400m2

phong ph ca c, ng vt khng xng sng, cc loi c kinh t, cc ng vt thn mm v gip xc trn phm vi ton KBTB v ti hu ht cc im gim st mc d gim mc khng ngha ngoi tr im Hn Vung. S lng cc loi c n (Trochus), da gai (hi sm) v cc loi gip xc (tm hm Panulirus) tn ti mc him tt c cc im. Nguyn nhn c kh nng xut pht t p lc ca hot ng nh bt lin tc v c l ngun b sung t. Tuy nhin, phong ph ca c n tng t 2002-2005 trong khi sao bin gai n san h li gim. Nguyn nhn c th xut pht t chng trnh iu chnh c t chc bi ban qun l KBTB. S bin mt ca loi trai ln Tridacna maxima v phong ph ca loi tm bc s c th phn nh p lc khai thc lin tc v mc ch thc phm v bun c cnh. V d, cc ng dn ln ng khai thc cc loi ng vt khng xng sng trong c cc loi trai, c ti bi Ngho ngay trc khi cc cn b khoa hc tin hnh chuyn kho st nm 2005. Loi c t v c s dng nhiu lm hng lu nim cng Cu . Ngun sn phm ny c th c khai thc ti a phng khc hoc c kh nng nhp khu t Philippine hoc cc ni khc v.

Phn b ca ng vt khng xng sng:

Nm 2002: So snh gia cc im gim st, mt cc loi ch th ph thuc nhm ng vt khng xng sng theo phng php reefcheck bin i ln. Mt Hn Tm cao nht (77,6 c th/m2) v Bi Bng t thp nht (7 c th/m2). Ti tt c cc im, Cu gai en (Diadema spp.) chim a s so vi cc loi ng vt khng xng sng khc. Tri li, cc loi c gi tr kinh t chnh (cc loi hi sm bin n c, tm hm panulirus spp., trai tai tng Tridacna spp.) rt him hoc khng pht hin thy ti cc im gim st l du hiu r rng chng t hot ng khai thc qu mc din ra rt thng cc vng nc ca KBTB. Sao bin gai (Acanthaster planci) l loi Sao bin ph bin nht vn pht hin mt s im vi mt dao ng t 1 3 c th/m2, mc d tin hnh cc t tiu dit trc cc tuyn kho st nm 2002.Giai on: 2002-2005: phong ph ca mt s ng vt khng xng sng suy gim trn phm vi KBTB t nm 2002-2005, trong suy gim r rt nht t 2002-2004 v tng ln t 2004-2005 (hnh 6). Xu hng ny xut pht t s thay i phong ph ca Cu gai en Diadema, v rng hu nh tt c ng vt khng xng sng hin din y u l cc loi da gai (hnh 6) v hu nh tt c l cc loi cu gai en (hnh 6). phong ph ca ging Diadema gim mc c ngha t nm 2002-2004, nhng cc nm khc th khng (bng 11).

Hnh 6: phong ph trung bnh ca tt c cc ng vt khng xng sng chn la (ngoi tr sao bin gai), tt c cc loi Da gai v cu gai en trn 100m2 din tch mt ct, KBTB vnh Nha Trang, 2002-2005Bng 11: S bin i phong ph ca Cu gai Diadema qua cc nm 2002-2005 trong KBTB vnh Nha Trang theo phng php phn tch bin n yu t ( t do 1, gi tr ti hn 3.9)NmMSFGi tr P

2002-030.2911380.7795150.378971

2002-045.99673117.76879< 0.0005

2002-050.000010.0000050.998256

S khc nhau v phong ph ca cc nhm cc him theo thi gian, c bn trong v bn ngoi vng li u mc khng c ngha (hnh 15-17) Cc loi b khai thc nh c n (Trochus), Hi sm v tm hm rn Panulirus rt him gp tt c cc mt ct (Bng 12, Hnh 7-9). Tng s lng tm hm m c dao ng t 0-3 c th, hi sm bin t 1 11 c th, chng t phong ph ca chng trong KBTB l cc thp. Tuy nhin, hin tng s lng c n Trochus tng nh trong ton b chuyn kho st (tng s t 3 16 c th) v s lng Sao bin gai gim c th l kt qu ca cc chng trnh kim sot c t chc bi Ban qun l KBTB.

c t v Charonia tritonis dng lm hng m ngh, trai tai tng Tridacna maxima v cc loi cu gai bt ch Heterocentrotus mammilatus v Eucidaris spp. khng pht hin thy qua tt c cc chuyn kho st trong 4 nm (bng 11). S lng loi tm bc s Stenopus hispidus, loi rt c gi tr trong ngnh bun c cnh, v cm nh bt vn tip tc gim, v trong chuyn kho st nm 2005 khng tm thy bt k c th no.Bng 12: S lng c th ca mt s loi ng vt khng xng sng chn la ghi nhn c trong KBTB vnh Nha Trang ti 8 im gim st t 2002-2005

Hnh 7: phong ph trung bnh ca sao bin gai v hi sm bin trn 100m2 din tch mt ct, KBTB vnh Nha Trang, 2002-2005. Ghi ch: Mean abundace: phong ph trung bnh; COTS: sao bin gai; Sea cucumber: hi sm

Hnh 8: phong ph trung bnh ca nhm thn mm bao gm cc nhm khai thc nh c n Trochus v trai tai tng Tridacna trn 100m2 din tch mt ct, KBTB vnh Nha Trang, 2002-2005. Ghi ch: mean abundance - phong ph trung bnh; Molluscs Thn mm; Trochus - c n; Clams - Trai

Hnh 9: phong ph trung bnh ca nhm gip xc bao gm c nhm tm hm rn b khai thc Panulirus trn 100m2 din tch mt ct, KBTB vnh Nha Trang, 2002-2005. Ghi ch: Mean abundance phong ph trung bnh; Crustaceans Gip xc; Lobsters Tm hm2.14. Tnh hnh nghin cu ng vt y Nam Yt Khnh Ha

Trong thnh phn loi ca khu h sinh vt bin ca qun o trng sa c th tch thnh 2 nhm c c im phn b khc nhau: nhm loi di ng xa, c s phn b rng theo khng gian v thi gian ph thuc vo cc yu t mi trng nh nhit , dng chy... v cc loi thuc nhm sinh vt t di chuyn, gn vi mt o, mt khu vc no o nh cc loi sinh vt y, rong bin, c san h, ng, thc vt trn cn.

- Giun t: Cho n nay mi pht hin c 23 loi thuc 16 ging, 11 h ca 2 lp giun nhiu t v tay cun. Cc loi giun ny u phn b trn rn san h, trong cc tng san h cht trn rn (Phm nh Trng, 1995).

- Thn mm: Thn mm l nhm sinh vt y c s loi phong ph nht. Tng s pht hin c 271 loi thuc 97 ging, 51 h, 8 b ca lp thn mm. Phong ph hn c l lp Gastropoda vi 220 loi, tip n l lp hai mnh v Bivalvia 50 loi, lp chn u Cephalopoda 2 loi v lp song kinh Amphineuura 1 loi (Lng Vn Kng, 1995).

- Gip xc: L nhm sinh vt y c s loi phong ph th hai sau thn mm. Cho n nay pht hin c 122 loi thuc 71 ging, 14 h. Trong phong ph hn c l h cua qut (Xanthidae) vi 75 loi, 56 ging, chim ti 61% s loi gip xc. Cc h khc c s loi t hn nhiu, 1-10%. Nhiu hn c l h cua bi (Portunidae) cng ch c 6 ging (8%), 13 loi (10%) (CaiYixiong at al. 1994, Phm nh Trng, 1995).

- Da gai: l nhm sinh vt y c s loi c pht hin ngho nn hn c, mc d sinh vt lng ca chng cao nh vo kch thc ln. Cho n nay mi pht hin v thng k c 20 loi thuc 20 ging, 13 h, 8 b, 5 lp. Phong ph hn c l lp sao bin: 9 loi, 9 ging, 5 h, tip n l lp hi sm: 5 loi, nhm bin 4 loi, ui rn 2 loi v hu bin 1 loi. Nhn chung cc con s ny cha phn nh y thnh phn loi v s a dng ca chng trn rn san h (o Tn H, 1991, Lng Vn Kng, 1995).

2.15. Tnh hnh nghin cu ng vt y Hn Cau - Bnh Thun

- Thn mm: Tng s c 119 loi thuc 71 ging v 42 h thn mm thuc lp chn bng (Gastropoda) v hai mnh v (Bivalvia) c xc nh trn rn san h trong vng bin xung quanh C Lao Cau. Cc h c s lng loi phong ph gm h Muricidae (13 loi), Conidae (11 loi), Cypraeidae (8 loi), Trochidae (7 loi), Arcidae (6 loi), Cymatidae v Strombidae mi h 5 loi. Cc loi c phn b rng v thng gp trn phn ln cc rn san h trong khu vc ny gm Pinna bicolor, Drupella conus, Trochus conus, Trochus histrio v Tridacna squamosa.

S lng loi ghi nhn c ti cc im kho st tng i thp, dao ng t 4 18 loi, trong cc im rn khu vc pha ng bc v ng C Lao Cau c s loi phong ph hn cc khu vc khc. Nhn chung, tnh cht thnh phn loi qun x thn mm c s khc nhau ng k gia cc khu vc.

- Da gai: C trn 32 loi thuc 27 ging v 20 h da gai kch thc ln c ghi nhn. Nhn chung, s lng loi ca mi h l khng nhiu (1-2 loi), ngoi tr h Hi sm (5 loi) v h cu gai (Diadematidae 3 loi). Mt s loi ph bin v thng gp gm Echinothrix calamaris v Diadema setosum (h Diadematidae), Tripnuestes gratilla (h Toxopneustidae) v Acanthaster planci (h Acanthasteridae). S loi ghi nhn c ti cc im kho st cng khng nhiu (t 3-10 loi/im), trong khu vc pha ng v ng bc C Lao Cau c s lng loi cao hn (t 7 10 loi) so vi pha ng bc v ty nam.

- Gip xc: ghi nhn c 46 loi gip xc, trong c nhiu loi quan trng v c gi tr kinh t cao. Vng bin xung quanh C Lao Cau cng c xem l ni phn b ca tm hm bng Panulirus ornatus v tm hm Panulirus versicolor.

Phn b mt ng vt khng xng sng kch thc ln: Mt tng s ca cc nhm ng vt khng xng sng (VKXS) kch thc ln theo Reefcheck ti 10 im kho st vo nm 2006 dao ng t 1,3 110,0 con/100m2, trung bnh 26,4 con/100m2. Khu vc rn pha bc v ng o C Lao Cau c mt VKXS dao ng t 1,3 110,0 con/100m2, cao hn nhiu so vi khu vc bi cn Breda (t 1,3 1,8 con/100m2) v vng ven b (t 1,4 14,5 con/100m2). Trong thnh phn ca VKXS, cu gai en Diadema spp. chim u th vi mt trung bnh 24,4 con/100m2 (dao ng t 0,0 108,4 con/100m2).

c n Trochus spp. v hi sm Holothuria spp. cng c mt rt thp trn hu ht cc rn, vi mt trung bnh tng ng 1,7 con/100m2 v 0,2 con/100m2. Trai tai tng Tridacna spp. ch ghi nhn c ti 2 trong s 10 im rn kho st vi mt ti a < 1,5 con/100m2, trong ch yu l 2 loi Tridacna squamosa v Tridacna crocea. Tm hm c xem l ngun li quan trng nhng cng ch ghi nhn c ti cc im rn khu vc pha bc C Lao Cau vi mt trung bnh < 0,5 con/100m2. Cc nhm ch tiu khc gm c t v (Charonia triton), tm bc s (Stenopus hispidus), cu gai bt ch (Heterocentrotus mammillatus) v sao bin gai (Acanthaster planci) khng c ghi nhn hu ht cc im rn kho st. S vng mt hoc hin din vi mt rt thp ca sao bin gai l du hiu tch cc v y l loi sinh vt ch hi i vi san h. Khi c hin tng bng n hoc hin din vi mt cao, chng s tiu dit hng lot san h v gp phn lm suy thoi rn san h nhiu khu vc trn th gii.

Bng 13: Nhm ch th ng vt y c ln trong rn san h C Lao CauCc nhm ch tiuKhong dao ngTrung bnh

c t v0,0 0,00,0 0,0

c n0,0 8,31,7 0,8

Trai tai tng0,0 1,30,1 0,1

Tm bc s0,0 0,30,03 0,03

Tm hm0,0 0,40,1 0,04

Cu gai en0,1 108,424,4 12,5

Sao bin gai0,0 0,10,01 0,01

Cu gai bt ch0,0 0,00,0 0,0

Hi sm0,0 0,50,2 0,1

Tng cng1,4 110,126,6 12,5

Ngun: Nguyn Vn Long v cc cng s, 2006

Ngun li ng vt khng xng sng sung quanh C Lao Cau bao gm mc (ch yu l mc ng Loligo spp. v mc nang Sepia spp.). ip qut (Chlamys nobilis), Dm (Modiolus philippinus) c sn lng kh ln (chim khong 5 6%) vi sn lng khai thc bin thin t 1 620 tn/nm (V S Tun, 1996). Ngoi ra, trai ngc Pinctada spp., bo ng Haliotis spp., c n Trochus spp., cu gai s da Tripneutes gratilla, hi sm Actynopyga spp., tm he, tm ro, tm t v tm hm (Panulirus spp.) cng l nhng ngun li c gi tr, nhng sn lng khng nhiu.

Ngun li tm hm c xem l quan trng nht trong nhm ngun li ng vt khng xng sng rn san h. Theo thng tin t ng dn a phng th khu vc pha ng v ng bc ca C Lao Cau c cc rn ngm l bi ca 3 loi tm hm bng (Panulirus ornatus), tm hm (Panulirus longipes) v tm hm xanh (Panulirus homarus). Sn lng khai thc c th ln n 8 10 tn/nm. Tuy nhin, ngun li ny b suy gim mnh do b khai thc cn kit.

Gi tr sinh thi kinh t ca a dng sinh hc: Vi s phn b rng, ph v tnh a dng ca thnh phn loi sinh vt rn kh cao, cc rn san h trong khu vc ny to nn s a dng cnh quan di nc. y c th c xem l iu kin thun li trong vic pht trin cc loi hnh du lch bin trong tng lai (bi ngm hoc ln c kh ti khm ph th gii sinh vt rn). Bn cnh , do nm trong vng nc tri c nhit nc bin tng mt thng thp hn nhng ni khc nn cc rn san h trong khu vc ny c tnh thch ng cao hn v t chu nh hng ca s gia tng nhit nc bin. Nh , chng c tn ti v pht trin v c xem nh l nhng rn ngun trong vic duy tr kh nng cung cp ngun ging cho nhng khu vc ln cn Vit Nam v Bin ng trong tng lai do s bin i kh hu.2.16. Tnh hnh nghin cu ng vt y Ph Qu - Bnh Thun - Lp mt mnh v (Gastropoda): c 40 loi thuc 13 h, 3 b, cc h c s loi nhiu bao gm h c n (Trochidae) vi 8 loi, c xng (Muricidae) - 8 loi); cc h cn li c t 1 n 6 loi. Trong tng s 40 loi thu c, cc loi ph bin nh Drupella cornus, Coralliophila neritoides, Trochus maculates, Trochus conus. Cc loi ny bt gp tt c cc im rn san h. Trong s ny, loi Drupella conus thng bt gp trn san h cnh, trong khi loi Coralliophila neritoides ch bt gp trn san h sng dng khi vi mt cao. Cc loi khng ph bin nh: Corallliophila radula, Fusinus nicobaricus, Hemifusus colosseus

- Lp hai mnh v (Bivalvia): pht hin 23 loi thuc 11 h, 5 b. S phn b thnh phn loi gia cc h khng c s chnh lch nhiu. Mi h c t 1 n 5 loi. Cc loi thng gp l Tridacna squamosa, Tridacna maxima, Isognomon quadragularis, Pinna attenuata, Pinna vexillum, Pinna bicolor, Pinctada margaritifera, Ostrea glomerata, Chlamys pica, Chlamys nobilis, Anomalocardia flexuosa, Meretrix meretrix, Arca antiquata, A. navicularis, Pinctada martensii.

- Lp chn u (Cephalopoda) l nhm sinh vt kinh t quan trng. bin Ph Qu- Bnh Thun c kh nhiu loi mc trong c mt s loi c gi tr kinh t nh Sepioteuthis lessoniana, Loligo chinensis, L. edulis, L. singhalensis, Sepia latimanus, Octopus vulgaris Cc loi mc ng (Loliginidae) thng trng vo ma h t thng 4 n thng 9 cn mc nang (Sepiidae) thng trng vo thng 12 n thng 3. Phn b ca mc thng tp trung su t 30 - 50m. y l ng trng mc quan trng ca pha nam min trung v c nhng vng l bi chnh ca mc v vy vo cc ma trn ng dn thng nh bt c nhiu mc mang trng. Cc ngh khai thc chnh l cu mc, chp, vy v li ko.

- Giun nhiu t: Tp hp cc kt qu nghin cu c c trong 2 t kho st v sinh vt bin khu bo tn bin Ph Qu, cho n nay ring v giun nhiu t thng k c 60 loi thuc ngnh giun t, trong lp Giun nhiu t c 23 loi. S loi trn thuc vo 18 ging v 12 h. Nhn chung, s loi trong cc ging hay h u thp, ch khong 2 - 4 loi. Rt nhiu ging hay h ch c 1 loi. Nhn chung, s loi Giun nhiu t trn th hin tnh thch nghi vi th nn y cng trong cc thn san h.

- Da gai: Kt qu phn tch mu vt, x l cc s liu thu thp c t chuyn kho st thng k c 38 loi ca ngnh Da gai. Trong lp Hu bin (Crinoidea) c 1 b, 3 h v 5 loi. Lp Hi sm (Holothuroidea) c 3 b 4 h v 9 loi. Lp Sao bin (Asteroidea) c 1 b, 2 h v 5 loi. Lp Cu gai (Echinoidea) c 3 b, 4 h v 7 loi. Cui cng l lp ui rn (Ophiuroidea) c 1 b, 7 h v 12 loi. Cu trc khu h Da gai khu bo tn bin Ph Qu c th hin trn bng 14.

Bng 14: Cu trc thnh phn loi ng vt Da gai khu bo tn bin Ph Qu

LpBHGingLoi

Hu bin (Crinoidea)1335

Hi sm (Holothuroidea)3469

Sao bin (Asteroidea)1345

Cu gai (Echinoidea)3467

ui rn (Ophiuroidea)17812

Cng9202738

2.17. Tnh hnh nghin cu ng vt y Cn o B Ra Vng TuCn o khng ch l mt trong nhng a im pht sinh loi ca vng bin Vit Nam m cn l ni pht sinh loi trong vng bin ng Nam , vng bin c nhng c im c lp vi cc h sinh thi t lin, t ch nh hng ca cc hot ng kinh t t t lin. Chnh v vy, Cn o to ra nhng h sinh thi c trng, nhng h sinh thi ch ni y mi cn c lu gi cho n ngy nay.Tuy nhin vn tim n nhng nguy c suy thoi t vic pht trin ngnh cng nghip trn bin, trong c bit nht l ngnh khai thc du m v vn ti bin ang din ra vi quy m ngy cng ln v l hng pht trin vn ti quan trng ca cc ngnh kinh t khc, p lc ln h sinh thi bin ngy cng tng v tin nng pht trin kinh t trn o cng ang l nhng nhn t lm thay i cc gi tr sinh thi ti ni y. Nhng nghin cu, pht hin ra nhng hin trng v xu th bin i ca cc h ng vt ti y l nhng c s khao hc cho vic iu chnh cc quy hoch mt cch hiu qu mang li nhng gi tr thit thc cho cc ngnh kinh t c lin quan v thc hin cc cng c bo tn cc loi ng vt hoang d m chnh ph Vit Nam k kt vi cc t chc Chnh ph v Phi chnh ph trn th gii.

Qua nhng nghin cu bc u t cc h sinh thi m ch trng nht ti h sinh thi san h, h sinh thi c v tr quan trng nht trong vic duy tr v pht trin cc h sinh thi khc ti Cn o v cng nh cc h sinh thi san h ti cc o khc ti vng bin Vit Nam. Biu bin ng vt khng xng sng ti vng rn Cn o c chng ti th hin trn hnh 9.

Hnh 9: Biu bin ng mt nhm ng vt y Cn oQua biu phn tch cc gi tr ng vt y ti Cn o cho thy, mt ng vt y ti y khng ch ph thuc vo gi tr phn b ca Cu gai en m cn ph thuc vo gi tr phn b ca Trai tai tng. Thnh phn 2 nhm loi ny quyt nh n gi tr phn b ca mt ng vt y khng xng sng ti Cn o. Mt khc, nhn vo gi tr bin thin ca tng nhm loi qua hai nm kho st cho chng ta thy cc gi tr c tin hnh kho st nm sau cao hn nm trc, iu ny cng c th hin trn gi tr trung bnh ca 2 nm 2007 l: 158, 250 v nm 2008 l 210,667 con/500m2. Trong , mt trai ti tng ti y c bin ng ln gia 2 nm, nhng nm 2008 chng ti tp chung nghin cu trn nhng vng c phn b trai tai tng ln ti Cn o (trong khu vc ng Bc o l khu vc phn b chnh ca loi trai tai tng) nn tnh trung bnh mt 2 nm c s bin ng. Theo tc gi Nguyn Long v V S Tun, 2003 loi trai tai tng phn b vi mt 20 c th/100m2 (tng ng 100 c th/500m2) cho thy mt trai tai tng ti y khng c bin ng so vi kt qu m chng ti thu thp, kho st. Tuy nhin, trong nhm trai tai tng phn b ti Cn o th ch c hai loi phn b chnh l loi Tridana crocea v loi Tridana maxima y l 2 loi trai tai tng c kch thc nh v vy gi tr kinh t cng rt thp. Loi c kch thc ln nh loi Tridana Squamosa c kch thc ln c mt phn b rt thp. Trong qu trnh kho st, iu tra thu mu, cc loi Tm bc s cng c nhm nghin cu chng ti ghi nhn c xut hin ti khu h sinh thi san h Cn o, tuy nhin th tn xut xut hin loi ny khng nhiu, cc nhm loi khc nh Tm hm, c t v cng bt gp trong qu trnh tin hnh thu mu nh tnh, tuy nhin tn xut bt gp rt t. Theo tc gi o Tn H, 1996 mt ca loi Hi sm c nhng trm kho st ln ti 375 c th/m2 (loi hi sm en bng mng Holothuria leucospilota). Trong khi , theo Vn Khng v ctv, 2008 ch ghi nhn c nhng mt ct c s loi hi sm ln ti 4 c th v trung bnh ton o ch t 0,75 c th/500m2, iu cho thy cc gi tr v s lng lun c nhng bin i nghch so vi thi gian, y khng phi l tnh trng ca ring o Cn o m l tnh trng chung ca ton vng bin Vit Nam. T nhng s liu tch cc qua 2 nm kho st (2007-2008) v so vi cc o nghin cu khc tc gi thy rng gi tr a dng sinh hc ti Cn o l rt cao, cc h sinh thi ti y ang trng thi tt hn cc o tin hnh kho st khc cho cc sinh vt sinh sng v pht trin. Cn o cha c thnh lp Khu bo tn bin nhng c Vn quc gia Cn o, chnh c s qun l cht ch ca ban qun l vn m cc h sinh thi ti y c bo v an ton trong mt phm vi nht nh so vi cc o khc. y c th thy l mt minh chng c th nht cho vic thit lp khu bo tn bin, nu nh chng ta c nhng quy nh c th cho tng ngi trong cng cc qun l, nh vy cc gi tr sinh hc khng ch c duy tr bn vng m cn gip cho chng pht trin ngy mt tt hn.

Nhm ng vt da gai ti Cn o c 8 b, 11 h v 19 loi. Thnh phn phn b ca chng c chng ti th hin trn bng 15. Theo nhng nghin cu trc y m tc gi o Tn H, 1996 l ngi c cng trnh nghin cu y nht v nhm ng vt da gai, trong thnh phn loi phn b ti Cn o so vi nhng nghin cu trc y, mt s loi khng cn thy xut hin trn cc h sinh thi nh loi hi sm Stichopus choloronotus, Pentacta anceps, Actinopyga echinites, A. mauritiana, Microthele nobilis.. v loi sao bin Stellaster equestris, Leiaster leachi, L. speciosus, Asterina cepheus V s lng thnh phn loi chng ti iu tra c so vi tc gi o Tn H cho thy s lng cng gim nhiu. Bng so snh s lng thnh phn loi ca Hi sm, Cu gai, Sao bin so vi tc gi o Tn H, 1996 c chng ti th hin trn bng 16. S suy gim s lng v thnh phn loi l vn chung trn ton vng bin Vit Nam, nhng ti Cn o vn cn nhng loi m hu ht cc h sinh thi ti cc ni khc khng cn xut hin nh loi tm Bc s (Stenopus hispidus) v loi c T v (Charonia tritonis). Nhmg s liu trn cho chng ta thy gi tr a dng loi ca Cn o vn rt cao, cc h sinh thi ti y vn p ng c cho cc loi sinh sng v cn c bo v pht trin v duy tr cho cc vng khc.

Bng 15: Bng so snh thnh phn loi da gai ti Cn o

STTLpo Tn H,

1996Kt qu nghin cu 2008S loi tng, gim

1Cu gai106-4

2Hi sm125-7

3Sao bin781

Ngun: Vn Khng v ctv, 2008Bng 15 cho thy, s loi da gai ti y u gim i so vi nghin cu trc y, c bt l loi hi sm gim i qu na t 12 loi xung cn 5 loi. Do c im loi ny c kh nng di chuyn chm chp v c gi tr kinh t nn ngi dn d khai thc dn n mt s loi c nguy c tuyt chng. Trong mt s loi khng cn thy xut hin trong qu trnh iu tra nghin cu. Bng 16: Thnh phn loi phn b ca nhm da gai trn vng rn san h Cn o

LpBHLoi

Sao binPaxillosida AtropectinidaeAstropecten spp

SpinulosidaAcanthasteridaeAcanthaster planci

EchinasteridaeEchinaster luzonicus

ValvatidaOreasteridaeGymnanthenea laevis

Culcita novaeguineae

OphidiasteridaeLinckia multifora

Fromia milleporella

Ophidiaster sp.

Hai SmAspidochirotidaHolothuridaeActinopyga lecanora

Holothuria atra

Holothuria leucospilota

Holothuria hilla

StichopodidaeStichopus ocellatus

Cu GaiAulodontaDiaematidaeEchinothrix calamaris

Diadema setosum

Echinothrix diadema

Cama