Ghép và trồng từng phần của cụm san hô thuộc các loài scleractinian khác nhau trên rạn san hô ở việt nam

TRANSPLANTATION AND CULTIVATION OF FRAGMENTS OF CORAL COLONIES OF VARIOUS SCLERACTINIAN SPECIES ON A REEF IN VIETNAIM Yu.. Many publications are available on transplantation and cuUiva

TRANSPLANTATION AND CULTIVATION OF FRAGMENTS OF

CORAL COLONIES OF VARIOUS SCLERACTINIAN SPECIES ON A

REEF IN VIETNAIM

Yu Ya LatvDov' N.I Selin', IM.L Bui^ L.Q.Pham'

1 A.V Zhirmunsky Institute of Marine Biology, Far East Division, Russian

Academy of Sciences, Vladivostok, 690059 Russia

2 Nha Trang Institute of Technology Research and Application, Vietnam Academy

of Science and Technology

3 Institute of Natural Products Chemistry - Hanoi, Vietnam Academy of Science

and Technology

The economy of Vietnam is developing rapidly The coastline of Vietnam has

become a site of intense house- and road-building; dozens of new hotels and diving

centers have recently appeared here, and sea farming is developing extensively

This intensification has become a cause of increased terrigenous effluent into

waters of local bays Local coral reefs are subjected to deposition of 70-100 g/m2 a

day, and this estimate grows one order higher during typhoons (Vo, Hodgson,

1997; JlaTbinOB, 2003)

Erosion processes along the coastal line at the city and port of Nha Trang, as

well as developing sea farming in coastal waters of neighboring islands, aggravate

the sedimentation and eutrophication impact in Nha Trang Bay (An et al., 2000;

riaBJioB H flp., 2004) An increased amount of microparticles of different origins

increases water turbidity caused by deposition, leads to impairment of

photosynthetic abilities of reef building corals and other benthic organisms, and

reduces physical and biological processes in the sea (Soong, Chen, 2003) As a

result, coral cover of the substrate reduces to 20-40%, while the portion of

substrate cover by macrophytes Chnoospora and Halimeda grows to 60-80%

General reduction of the area of coral reefs has recently been documented

(Latypov, 2006)

Many publications are available on transplantation and cuUivation of coral

fragments; they cover various methodical, physical and biological problems

connected whh coral cultivation A majority of researchers believe that the

attention of those engaged in the matter should be focused on the size of coral

fragments, the season of their transplantation, orientation in the place of

transplanting, and selection of substrate These factors are most important for

restoration of reproductive abilities of new coral colonies reared from fragments

(Okubo, 2005) Based on our positive experience in cultivation of corals, we

analyzed presumably species-specific peculiarities of regeneration of fragments

and growth of new coral colonies of the genera Acrbpora and Porites, belonging to

the families Acroporidae and Poritidae

Workshop: 'international Cooperation on Investigation and Research of Marine Natural Resource and Envimnnv.wi.'^

More 20 species of genera Acropora, Isopora, Pocillopora, Porites common

scleractinian were studied; which predominate in reef communities of the Indian and Pacific oceans, including also the area of Viemamese waters Experimental facilities were placed on the reef slopes of Mun Island in Nha Trang and Cam Ranh Bay, beyond the activity of open seawaters Judging from the presence of a natural reef in this locality at a depth below 12 m, the experimental installation was illuminated by sufficient light, which is crhically important for viability of hermatypic corals As compared to other localities, water turbidity and intensity of sedimentation were relatively low during our experiment The water transparence and intensity of water exchange in coral settlements were 1.48 times higher at the island than at other islands along the coast (An et al., 2000)

Altogether, about 150 fragments were selected from 30 donor colonies tliat were 1-1.5 m high and 2.5-4 m in diameter All but one donor colony grew at a depth of 2-3 m Peripheral parts of coral colonies with 2 to 17 branches were used for the experiment The length of fragments was measured with a slide gage anii three size groups were distinguished: small (40±.05 and 7±0.06 cm), medium'fll 12±0.09 cm), and large (20-21±0.41 cm) Survival and growth rates of transplanted

c o r a l f t a g n e n ^ v e r ^ n v e s % with respect to (I) species, (2) orientation at

• " • " • ^ • • ' • ' • • • • • ^ attachment, (3) transplantation season, and (4) size

of transplants Transplanted fiagments were fixed

to the frame of the facility either vertically, horizontally, or with a growing distal tip downwards The frames were installed on vertical supports, 30-40 cm above the bottom, in order to prevent covering of the fragments with sediments, Fig 1 Plastic installation Coral fragments were fixed to horizontal rods of witii transplanted coral the facility with „ plastic-covered copper wire fragments on the reef slope of (Fig 1) In order to avoid attacks of crawling

Mun Island predators, e.g., Drupella rugosa

Results

Survival of transplants

All fragments that survived after transplantation recovered and formed new

finl" f ' „ " ? ' " ' T * ' " * ' ' "^^'^ intemionally injured also recovered About

du/o ot all fragments fused over 6-8 months with their bases onto horizontal rods

unrecovTrTd"' " " " ^ ^ ' " '"'"''^*^- '^'^^ fragments sized lOO-l 10 mm died Formation of new branches

t e s t l m i i " ™ ' " " " I ' ' ' ^^^^ •'^"splantetion, new branches and their buds in all

o w e r n n ! 7 " " ' , , " ' " ° " * ' '"''^''^^ of surviving fragments, including the

0 60 new b t , " ' ' ' ^ ' ' ' ' ' ^ " ' ' " ' ' * " ^ P^'^^" from the donor colony Fron,3

60 new branches grew on fragments of different coral species over 12-18 ,

342

months Very branchy fragments of ^ elseyi and A valida of different size groups

with numerous ranches formed the highest number of new branches and

subbranches Every transplanted fragment this species developed five to nine new

basic branches and about 24-32 subbranches of different levels It is worth noting

that the average monthly accretion of medium- and large-sized fragments and the

number of new branches was of fragments 1.20- to 1.37-fold higher at spring

transplantation than at autumn transplantation This was especially characteristic of

P cylindrica and A valida fragments

Linear accretion

Linear accretion of coral fragments was 70-160 mm during the period of the

experiment The grovrth rate depended on the species, fragment size, and season of

transplantation Morphologically different fragments of A palifera, P cylindrical,

Pocillopora verrucosa, A valida and A valenciennesi had different grovrth rates

Among these species, higher linear accretion was found in fragments of more

branchy A valenciennesi (Fig.2) Within the same species, fragments of larger

sizes grew 1.3- to 1.5-fold longer than medium-sized fragments Prolongation of

the period of cultivation from one to one-and a-half years enhanced the linear

accretion 1.2- to 1.4-fold

The study showed the efficiency of transplantation of fragments of branchy

corals onto an artificial construction installed in the natural environment on a reef slope and elevated over the bottom Fragments with numerous branches formed more new branches of the

X xii 11 IV in vu IX X xii u in j ^ ^ g arrangement as in the

- O - A palifcia —a-P cyliltdrica -*—A valenciennesi

donor colony; they had a Fig 2 Growth rates of transplanted fragments of greater surface area of live

different coral species polyp (jsjue per unit of the

total fragment length Their ability to obtain energy at the expense of photosynthesis or captured food particles

is appreciably higher than in small fragments with smaller surfaces (Soong, Chen,

2003) The relatively high grovrth rates of fragments of all species niight be

explained by their displacement to a new well-illuminated location which is less

populated by other benthic organisms It is also important that the installation was

elevated 30-40 cm over the silty bottom, since silty deposits often limit coral

grovrth and are sometimes even the cause of their death The location of fragments

over the bottom reduces the probability of their covering with silt (Ocubo et al.,

2005)

Large-sized fragments of all coral species survived better and had higher growth

rates They formed agreater number of new branches and then- buds and formed new large-sized colonies This agrees well with the opinion of many researchers who correlate the size of recovered colonies with the size of original iragmenfs (Soong, Chen, 2003) Large-sized coral colonies reared from fiagments had the best fecundity It was documented that the percent of spawning colonies obtained fi-om transplanted fiagments depended on the size of the transplants (Ocubo et aL 2005)

Growth of corals from fiagments is an important natural process, at least, in corals with branchy forms of colonies Colony fiagments first anchor somehow occasionally on the bottom, then adhere to the substrate through regeneration and outgrowth of soft tissues and skeleton (IIpeoSpaKeHCKHH, JlaxtinoB, 1980' Heyward, Collins, 1985) Our results do not contradict the conclusion of Okubo et

al (Ocubo et aL, 2005) who concluded that attachment to the substrate is a precondition of a successful long-term process of transplantation All fragments of

Acropora and Porites that survived in our experiment fused to the wire that fixed

them onto the experimental installation Two-thirds of fiagments adhered to horizontal rods of the installation and blended to them with the basal part of their colony body A high rate of blending to an artificial substrate can testify to a good state

of the colonies formed from recovered fragments

Inltiiil dimensions and accreticnof frasments.mm

40tlr

xn n IV V.05

Fig 3 Growth rates of coral fragments of

the genus Acropora in different size groups

-*-i.fimatg -B-A.«l»}t'

The results of the experiment revealed a certain relationship between growth of transplants and their species The row of coral

species A palifera, A formosa, A valida, A valenciennesi, and P cylindrica

distinctly represent a growing complication of colonial stmcture The presence of numerous branches of different levels and axial and radial corallites makes for a more rapid and more successfiil growth of new colonies fi'om the fragments (Figs

2,3)

Thus, our study showed that survival of coral fiagments in ambient conditions of a natural coral reef depends on various factors; the main factors are coral species and size of fragments The relatively high growth rates of fragments of all species can probably be explamed by their ttansplanting to a well-illuminated medium less populated with other benthic organisms The obtained data can be used for successfiil recovery of natural settlements of corals or

\Wm

\

Artificial growled

six-month colonies of A.valida

for cultivation of corals to satisfy the requirements of coral-hunters; effective coral

cultivation could relieve the present pressure on natural coral reefs

Acknowledgment:

The author extends his sincere thanks to Khanh Hoa Salanganest Nest Company

(Sanest group) and Open Russian-Vietnamese Laboratory of Biochemistry of A.V

Zhirmunsky Institute of Marine Biology Far East Division Russian Academy of

Sciences (IBM, Vladivostok) and Nha Trang Institute of Technology Research and

Application Viemam (NITRA, VAST Nha Trang) and Institute of natural Products

Chemistry -Hanoi (INPC-VAST), for financial support of this research, as well as

to p.T Luong, H.D Lu, L.N Hau, N.B Khoa and V.T Trung employees of these

Institutions, for their help during field survey

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