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ASSESS~ENT OF HUMAN IMPACT ON GIANT CLAMS
(TKIDACNA MAXI~lA) NEAR JEDDAh, SAUDI ARABIA
ALAIN BODOY*
Faculty of ~Iarine Sciences, King Abdulaziz University,
• Jeddah, Saudi Arabia
AbSTRACT
A reprint from
PROCEEDINGS OF THE SYMPOSIUM ON COR1\.L REEF ENVIRONMENT OF
THE RED SE 1\.
Edited by
MASSOUD A. H. SAAD
1984
2/ -
1
1
1
ASSESS~ENT OF HUMAN IMPACT ON GIANT CLAMS
(TKIDACNA MAXIMA) NEAR JEDDAH, SAUDI ARABIA
ALAIN BODOY*
Faculty of ~Iarine Sciences, King Abdulaziz University,
• Jeddah, Saudi Arabia
AbSTRACT
A reprint from
PROCEEDINGS OF THE SYMPOSIUM ON CORllL REEF ENVIRONMENT OF
THE RED SEll
Edited by
MASSOUD A. H. SAAD
1984
z 1 -
Proc. Symp. Coral Reef Environ. Red Sea, Jeddah, Jan. 19H4:472-490.
ASSESS~ENT OF HUMAN IMPACT ON GIANT CLAMS
(TKIDACNA MAXIMA) NEAR JEDDAH, SAUDI ARABIA
ALAIN BODOY*
Faculty of ~Iarine Sciences, Kin9 Abdu1aziz University,
Jeddah, Saudi Arabia
AbSTRACT •
A quantitative, eco10gica1 study was carried out on severd1
populations of the bivalve Tridacna maxima, in order to assess
the chdnyes due to the collection of this species. Four
transects were made across fri ngi n9 reefs whi ch differed from
their accessibi1ity, but exhibiting the same orientation and wave
exposure.
In an undisturDea area, the number of inoividua1s found
a10ng a transect was 63, the average 1 ength, 134 lTIil and the
biomass, expressed in ary weight of tissues and re1ated to one
metre of shore, B8 g.m-1. In se1àorn uti 1ized area, those
parameters were 19 individua1s, 113 mm and 18.6 ~.1,,-1 respective1y, while, in an area subjecteà to intermediate
exploitation, 4U individua1s were found, with an average size of
b9 mm and a biomass of 5.7 g.m- 1. At a high1y utilized
beach, on1y 6 individua1s were found, with an average 1ength of
82 mm and a biomass for one metre of shore of 1.5 g.m-1
.
The effect of such human impact is aiscussed, accorainy to
. the eco10gy ana the bio10gy of this species.
(*) Permanent address: Laboratoi re Cultures l'iari nes IFKL~IEk
b.P. 19u,17 39U La Tremblade, FRANCE.
473
INTRODUCTION
Among the different species of invertebrates co10nizing
coral reefs in the Indo-Pacific area, the giant clams of the
genus Tridacna are a dominant feature of the sha110w waters were
they are living (Rosewater, 1965). They are probab1y the 1argest
bivalves which have ever existed, and the Pacific species,
1. giyas, can reach one metre in 1ength. From a bio10gica1 point
of view, their association with symbiotic a1gae, which was
studied by severa1 authors (Yonge, 1936; Jaffrey and Haxo, 1968;
Goreau et al. 1973 and others), enab1es us to consiaer species -- '. of the genus Tridacna as phototrophic, primary producers.
Indeed, the metabo1ism of the zooxanthe11ae contributes to their
nutrition (Ricara and Sa1vat, 1977).
They are a1so of an economic interest, since they are eaten
in many countries and the adductor musc1 e has a very high
commercial value in South-East Asia (~lunro and Gwyther, 1981).
Some atternpts were made to eva1uate their aquaculture feasibility
(Beckvar, 1981; Munro and Hes1inga, 1983), and the possibility of
rearing of tridacnid's 1arvae (La Barbera, 1975; Jameson, 1976;
Gwyther and Munro, 1981).
In spite of being essentially reef-top inhabitants,
re1ative1y few works have been carried out on their growth,
population size and biomass (Sa1vat, 1971; t1cMichae1, 1974;
Richard, 1977 and 1981; A1ca1a, 1981; Beckvar, 1981) .
Along the coasts of the Red Sea, two species are usually
found, T. maxil,la and T. squamosa (Hughes, 1977; ~leryner and
Mastaller, 19BO), the first one being the most abundant. These
species are submitted to heavy exploitation in the vicinity of
Jeddah, Saudi Arabia, and they are often collected on the reef
li zi ng
f the
were
rgest
Cl es,
point
was
1968;
ecies
cers.
thei r
=aten
high
J81 ) •
il ity
:y of
976 ;
.nts,
wth,
974;
ally
and
he se
1 of
reef
-- .
flat, both for food and for decorative purposes .
The present study aims to assess on quantitative basis the
human impact on T. maxima. Therefore, abundance and biomass were
estimated for several populations of this species living in areas
differing for their accessibility. Similar studies, following the
same goal , have been carried out on corals (Antonius, 1984) and
on fishes (Oakley, 1984).
•
~IATERIALS AND I1ETHOD
The analysis of different populations of T. maxima has been
carried out using a transect technique . Four different transects
were studied in sites differing in the extent to which they are
affected by human impact (Fig. 1). The site located North of the
port of Tuwwal, because of its military importance, is strictly
protected by the coast-guard, and may be consi dered to be an
unai sturbed ar ea . The second site studied i s about 180 km South
of Jeddah. 80th the distance and the state of the road leading
to it make its access difficult. A third site was on the reef,
North of Sharm-el -Abhur, whi ch i s one of the favourite beach
spots for Jeadah people auring week-ends, and the last transect
was studi ea on Jeadah northern Corni che, 3 km North of the
desalination plant. The latter area, turned into an artificial
beach, is very popular, due ta its easy access. Since this work
was carried out, a development scheme on the reef flat has
destroyed the studied area.
I:.ach transect cons i stea of a band, 10 m wi de, across the
reef flat, from the shore-line to a depth of 2 m at the
beginniny of the outer slope. Along each transect, all the
indiviauals of T. maxima were counted and the maximum antero-
475
Tuwwal
•
•
20 Km
N
t Shoiba
RED SEA
Fi~re 1. Location of tIle four transects a10ng tI1e œasts of tIle kea Sed.
476
posterior length measured with a maryin of error of + 2 Iffi]. The
transect was divided into five metres wide sections, each of
50 m2 area.
Abuut 20 individuals, chosen as so to coyer the whole span
of length found in the field, · were also sampled in order to
establish the relationships between length and weight leading to
IIleasures of biomass. For that purpose, the specimens were
arained, to obtain a total weight accurate to 0. 01 g, and then • opened. The flesh was weighed to obtain the fresh weight and
then dried for 24 hours at 85°C and rewei ghed, to get the dry
weight. The logarithmic relationships between length and total
weight, fresh weight and dry weight were calculated using
regression techniques. The values of biomass were then
calcul ated for each unit area of 50 m2
. To improve on the
accuracy of these quantitative data, additional perpendicular
transects were carriea out in areas of high density, such as the
edye and the inner flat, near the algal crest.
Length-frequency distributions of the clams were calculated
by includir.g all the animals for each main transect.
RE5UL T5
The constants in l ength-wei ght rel ati onshi ps are shown in
Table 1. Using these coefficients, the dry weight of each animal
was calculated from its length. Fig. 2 shows the results for the
undisturbed area of Tuwwal, including the number of individuals
obtained for each unit area of 50 m2 along the transect, the
biomass (dry weight) of T. maxima corresponding to each unit area
(in 9.10-2), and the depth profile of the reef flat.
From a morpholoyical point of view, the reef flat
neighbouring the shoreline is composed of a sandstone tile,
477
Number 01 indiyidu.ls / 50 m 2
':t~~mL..l..LL..LJ.LLL~o m Biomass
3
2
Depth (m)
2
1 gure
50 100 150 300 m
----------~a 1 gal r id ge
Inn", reel liaI undance an lomass 0 rl acna
transect across the reef flat in the undisturbed area
(Tuwwa 1) .
Number of indiyiduals /50 m 2
': t,-------,-----L--L..LO --'..LU...LL-O 1 m ~O db --LL-.WJ..LjO JJ~ Biomass dry wei ght (g / m 2 )
3 -
2
lf-•
1 1
50 100 Deplh (m)
-------1 -
21--
1
150
1
algal
.+ n n-J1 1
200 250
, out er : reef
300 m
:id9~; 1
inn e r r eet fi at 'fiat Figure 3. Abundance and biomass of Tridacna maxima along a
transect across the reef flat in a slightly disturbed
area (Shoiba).
478
slight1y covered with si1t, and is popu1ated with Cau1erpa
racemosa, which first is scattered and then becomes more numerous
as one gets nearer the end of the sandstone ti1e (150 ml. Rocks,
uneven1y scattered and surrounded by sandy patches, were then
found, as were the first T. maxima. Further towards the open sea,
rock formations become denser whi1e C. racemosa disappears. The
highest densities of T. maxima were found in this zone, between • 200 to 240 m from the shore. Further on, a very dense belt of
seaweeds (Sargassum sp.) is located at the top of the a19a1 rioge
(Fig. 2), as defineo by Battistini et al. (1975), and no T. , --maxima were found there. However, at the ena of the outer reef
f1at (Fig. 2), individua1s were sett1ed. The externa1 slope, not
stud ied here, was sometimes inhabited by scattered , large
inaiviaua1s.
The total number of individua1s found a1on~ this transect
was 63, the majority of which were on the reef f1at. The 1ar gest
one measured 23 cm, and the smallest, 6 cm. The average size for
the who1e of the transect was 13 . 4 cm, whereas for inuividua1s
from the inner reef f1at (Fig. 2), betwen 195 and 25U m, it was
13 .6 cm.
11 CTiI.
The average size of those 1 iving beyond the rioge was
-2 The highest biomass was 3.U6 9.01
If une considers a band of one metre width, perpendicu1ar to
the shore, the biomass can be expressed in grams per 1 inear Tiletre
of shore, which allows a comparison between fringing reefs which
are not of the same extension. For the Tuwwa1 site, the biolilass
-1 of the population of 1. maxima was 88.12 g.m of shore .
The fringing reef located Sou th of Sho iba (South of the
aesa1ination plant for Hakkah city), is different in various
ways. Its width is greater (505 m) and for the first 2UO 01 from
N~:Lber 01 ,ind, ividuils
. 1 rD-O rill 0 0 rD-O ,~-L ______ -L ______ ~ ______ ~~~WU~U--LWUL
Biomass dry weight (g 1m2 ) 3-
2
lLr __ ~~I~I ______ LI ____ ~ ______ lu~n-~lli~hun~L~UiL , , 250 300 350 400 450 500 m
Depth Cm) ~--~ L(-r------,-------,-------.-------~------. ~ ~I __ ~__ 1 1 1
1- algal~idge j t .ou er 2 : reef ,
inner reef Ilat ,flat
Figure 4.Abundance and biomass of Tridacna maxima along a
transect across the reef flat in a visited area (Abhur).
Number or individuals 1 50 m2
':t DI 0 DO
Bicmass dry weight (g/m 2 ) 3 c-
2 -
1-
• 1 ' , , , ,
50 100 150 200 250 m Depth (m)
1 1'---, , -' .' ,
1
,,,./i~ 1 1-
"lgal
1 2 - 1 outer
: reef
1
in n e r r e e 1 lia t 'fla t
Figure 5. Abundance and biomass of Tridacna maxima along a tran-1 , sect across the reef flat in a heavily disturbed area
(Jeddah).
l
t
..
t
l -> l
t
(
2
> l
k
"
lm
a
Jr) •
In -
480
Table 1. Coefficients for the linear relations, (y = ax + b)
between the logarithm of the length (y) in ITITI and the logarithm
of the different weights (x) in g . Number of samples = 20. a =
slope of the straight line. b = intercept. r = correlation
coeffi ci ent .
a b r
• Total weight (live animal) 3.8043 - l .5834 O. 9914
Fresh weight (organic tissues) 3 .0739 - l .7238 0.9639
Ory weight (organic tissues) 3 .2237 -2.5890 0 . 9715
the shore, there is a zone of intense sedimentary accumulation,
with a large proportion of fine particles. This fine substratum
has not been coloni sed by seaweeds. At 300 m, a population of
green filamentous alyae (cf. Enteromorpha) appears. The alyal
belt of Saryassum is absent ana is replaced by a population of
Turbinaria cf. triquetra . The outer fringing reef consisted of
patches growing from a step 15 m deep, whereas, in the other
loc ations, the reef flat ended with a precipitous slope .
The distribution of the number of inoividuals and the
biomass along the transect are shown in Fig. 3. The population
of T. r,laxima was concentrated over the l ast 100 m of the
transect, and only 19 inaividuals were found. The Enteromorpha
zone had particularly few clams. The average length of this was
population was 11 .3 cm, but some individuals were up to 25 cm
long. The average biomass per linear metre of shore was 18.6 -1 -2 g .I,\ , and the highest biomass (2 y.m ) was found on
the outer fl at of the fringins reef.
The thiro transect was carried out on a popular beach, a few
kilorlleters North of Abhur creek. The width of the fringing reef
Wd S 275 \.. After a zone of back reef, composed of a seaiment of
481
a fine sand covering a flagstone, there were populations of thE
algae Padini. pavona and C. racemosa (Fig. 4).
The first individuals of T. maxima were found at 120 m from
the shore. On the top of the al ga 1 ri dge, where a very dense
belt of Sargassun, sp. was located, only one individual was found.
The total number of individuals was 46 over the whole transect,
while the biomass, expressed in grams per linear metre, was 5.7
g.m- 1 Ali the i ndividua ls however, were very small, with
dn averaye 1 ength of only 6.9 CIl1. The largest individual
"~asured 14 cm. Apparent ly, the distribution of the anima I s along
the transect was not size-related. The highest densities were
fuund on the outer edge, and Just after the
Du tar reef fIat. The highest biomass was 0.16
al gal ridge -2 g.m .
on the
The last transect, carried out on the North Corniche in
Jedddh, was 2H5 ,. long (Fig. 5). For the first 50 m, the bottom
was IIIade of a fi agstone covered wi th a very fi ne coat of sil t and
blue-green al~ae. Further on, the algal cover cunsisted in the
",ain of P. pavona, T. cf. triquetra and C. racemosa. The belt of
Sargassum sp. was weIl developed. The coral populations were
recoveriny slowly after having been heavily choked up with mud,
when the Corniche Road was built two years ago (Antonius, pers .
comn,.) .
The population of T. ["axima was very scattered. The absence
of valves fro~ dead individuals l eads one to think that the small
size of the popul .. tion was not due to d r"ortality resulting from
the ,~uu. On l y 6 individuals were fuuno, averaging ~.2 cm in
lell~th, the lar~est one ,nedsuring 11 c,,;. The biomass per linear
",etre of shore was the lowest of the four trdnsects: 1.5 9.01-1
The hi,jhest biornass was u.14 g.nr- 2 .
Fi~ure 6 shows the quantitative uata for the population of
the fuur stuoied areas. The average biùnrass indicates that these
four dreas can be c la ssified in the sa,lle way. The low number of
indiviouals fou na in Shoiba can be relateo to the presence of
.he
om
se
d.
t, ,
.7
th
al
ng
re
he
in
Jm
ld
)f
J,
:e
n
r
1
f
e
f
f
- - -482
Enteromorpha sp., which usually indicates either natural or
man-induced alterations in the quality of the marine environment.
The average size of the populations from Abhur and Jeddah varies
only within 5%.
The analysis of those different pop ul ations carried out 2 using criteria of density (number of individuals per 50 iii ),
of longevity (average size of the population), and of standing •
stock (dry weight) enables a classification of these populations
to be obta i ned, correspond i ng to the order es tab 1 i shed in terln 0 f
their accessibility. Since T. maxima is a sessile species, it is
likely that its scarcity in the most visited areas is mainly due
to excessive collection.
The analysis of length-frequency distributions for the four
transects (Fig. 7) leads to confirm these results. big
individuals, larger than 15 cm, were found on the undisturbed
reefs of Tuwwal and to a smaller degre2, of Shoiba. In botll
sites, the distributions are polymodal. In the two other areas,
only individuals smaller than 15 cm were founo, ano the shape of
the distribution is much sil11pler. In Jeddah, the number of T.
maxima found along the transect is too low ta allow any cOIl."ents
on a preferential exploitation size, but the large nurilber of
young individuals founo in Abhur transect clearly indicates a
size-dependant collection upon the largest animal s.
OI5L USSlUN
~Iuch attention has been paid to the symbiotic relation-
ships between the zooxanthellae and tridacnids. But fe w studies
have been carried out on the ecology of related species. The
density of T. maxilila can reach up to 224 individuals per square
metre, in
be scarce
the atoll of Reao (Salvat, 1972), but this species iOay
in other atolls (Salvat, 1971). t'Icl-iichael (1974) found
0 <.D
0 ~
0 N
Number of individuals
0 N
0
Average size mm
483
N
0
ci
0 0
0 111
Avera 9 e biomass glm2
'" ~ ~ ::J
1--
'" .0 L :6 ::J
.r: .r: .r: tf) .0 '" ~ u
U <l>
Biomass g lm c4 shore
Figure 6. Abundance of Tridacna maxima, average size, average
biomass in g.m-2, and average biomass for one metre
shore in g.m- 1 for the four sites.
-~ .
:r: <{
0 0 w ..
-a: ::J r m <{
<{ m .-0 r Vl
...J <{
3: 3:
- ::J f-
484
l 1 rdb p 1 1 ,
20r-r-~
-•
15 f-
r ~
10 f-
5 1- - -
-
1 -r n 0'-- ~ 1
5-
riln ri 1111 n p q 0- 1 1
10 -
-5 - -- - -- ~
-- - - -
~ - m . - -
0-5 10 25 20
r i oUl'e 7. L en " th -fr~ q u ~ "cy Gi s tri iJ ut io li of Triuac "d L,ax i 'dd fo r
til e f our s t uu i eo s ites .
25 cm
an dverage density of 0.8 T. maxin,a per square metre, at a site
on the Great barrier Reef.
These oensities are higher than in our study, since the
hi~hest densi ty recoraed was 0.22 i ndivi dua 1 s per square metre,
in Tuwwa1. In the Pacific Ocean, 1. maxima often sett1es in the
shallow wdters of 1ayoons, e.g. in the atoll of Takapoto
(kichard, 1~77). In the Rea sea,sett1ement in she1tered, shallow
waters close to the shore1ine was not recordea in any of the
fuur transects. This ana the 10w average density can be
exp1ainea by the pecu1iarities of the Red Sea coasts. During the
winter, co1d winds can 10wer the water temperature on the
sha110w, inner reef, sometirues down ta Il'C (Hughes, 1977), which
cou1d be a 1eta1 temperdture for many tropical species. On the
other hana, 100se sediments, acteo Dy waves, might 1imit
sett1e"~nt uf Red Sea populations.
The exposure can dffect the quantitative nistriDution of
T. n~xi ••. ~a1vat (1~70) encountereo this species on the windwaru
sioe of the barrier reef of Gambier Islands, but not on the
other, she lterea, 1 eeward si de. In our case, for all the
trdnsects, the reefs showea sÎlnilar, North-,outll orientation, ana
receiveo the prevdi1ill~ winds From the saine direction.
Therefùre, these ecu1o~icd1 fdctors shou1d not affect the
results.
Un1y very few e',ipty shell s were founn, ana since these were
a1ways 1ar~e, one Cdn dssun,e that lIiOSt of the ':Jorta1ity is
nldin1y nue to collectin~. This collecting rate seems ta vary ,
with the difficulty of access. Severa1 authors have estilllatea
the asy"ptotic 1enyth (1",,), corresponding to the averaye nlaxima1
size in the growth equation of Von ~erta1anffy, for different
areas. Tnese oata dre sUlillilarized by 11unro and Hes1 ing (1983).
Trie values are rankea frolil 12.4 CIII froll: a population coming frolli
an dtoll of French Po1ynesia (kichara, 1977 and 1%1), to 30.~ CIII
in New Gu i nea (['Iunro dno Gwyther, h. ~) . Uther values of this
estÎlllatea asyrdptotic 1ength are 24.3 Clil ( ~,unro and Gwyther,19ts1),
- ---.-- ~
486
27.5 cm (~ICr'lichae1, in Munro and Hes1inga, 1983) and 3U.5 cm
(l'ICKOy, 1980, in op.cit.) For all these populations, the
10ngevity was more than 20 years. Assessments on such 1 ongevity ,
based on she11s rings counts, agr~e with such resu1ts for Red Sea
populations (unpub1. aata). In these 10ca1ities, the asymptotic
1ength was ca1cu1 ated to be within 20.23 cm, if the transect of
Shoiba was excl uded, were individua1 s up to 25 Cln were observed.
Accordin~ to Rosewater (1965), the maximal recorded 1ength is 35
The growth ~quations given by McMichae1 (1974), Mu nro ana
Gwyther (l9U1) ana Ricllard (19é!1), indicate thât T. maxitlla wou1a
reach a 1ength of 12 c,,, in 6-13 years. Therefore, to regenerate
an overco ll ected popu1atioll to a norlola1 1eve1 (e.g. in Tuwwa1),
will take Iolany years, once collectin~ stops .
Mother prou1elll, re1atea ta th~ reproduction, Ilas to b~
men tionea. T. illax ima is il protanoric her;ilaphrodite. Richard
(1982) gave the following scherlle for a Po1ynesian population:
sexua1 IIlaturity is reach ed for ct size of 0 cm; after a ",ale
phase , up to 7 Clll, sitnultaneous hermaphruaites fon,l th e
population between 7 and 15 Clil. The 1arger inaividua1s wûu1d
have on1y feilla1e ~onads. ~ut, for Illost of the other populations,
those l ar~e animal s relnain s imu1taneous hermaphrodites.
According to Jaubert (lY77), T. maxima can reach a depth of 10 m,
after whicn tnere is not enouyh 1ight for the zooxanthe11.e to
photosynthesize. These specimens have often a 1 ar~e size, and
such big inaividua1s were Observed in the four 10ca1it ies, after
the end of the transects, dee~er than 2 r,i . It seelils that very few
bivalves are collected deeper then the ed~e of the outer reef
f1at, were they are on1y accessibl e by divilty.
Thi s preserved stock of 1 arye tri dacni ds shou1 d a110w tû
--------- -
487
avoid any long-term disappearance of the species by over
collectiny, as long as it remdins untouched.
ACKNOWLEDGE~IENTS
1 would like to thank Dr. J.L. l'iunro, both for his
scientific conments and for suyyesting ililprovements of the
English lanyuage.
REFŒlNCES
Alcala A.C., 1981 . Standing stock anu yrowth of four species of
mo11uscs (family Triaacnidae) in Sumilon Island, central
Visayas, Philippines. Proc . Fourth int. Coral Reef Synlp.
l'Ianilla, lYB1, 2: 757.
Antonius A.,1984. Hunlan impact on Corals in fringiny reefs near
Jeddah, Rea Sea. Proc. Symp. Cordl Reef Environ. Rea Sea.
Jeddah, January 19ti4:
~attistini R., BourrouiHI F., Chevalier J .-P ., Coudray J.,
Denizot ~I., Faure G., Fisher J.-C., Guilcher A.,
Harrllelin-Vivien ~1 ., Jaubert J., Lanorel J., hontagyioni L.,
l'iasse J.-P., ~Iauge L.-A., Peyrot-Clausade ~I ., Pichon 1'1.,
Plante R., Pla7"iat J.-C., Plessis Lb., Richaru G., Salvat
~ ., Thoillass in B., Vasseur P., "eydert P., 1975. El éments de
terminologie récifale . Téthys, 7 (1): 1-111, 77 Fig.
Beckvar N., 1981. Cultivation, spawniny and growth of the giant
cla~s, Tridacna yigas, Tridacna aerdsa, ana Triaacna
squamosa in Paldu, Caroline Islanas. Aquaculture, 24: 1-2.
Goreau T.F., Goreau N.I., Yonye C.h., 1973. On the utilization
of photosyntheti c prooucts frohl zooxanthe11 ae and of cl
488
dissolved amino-acid on Tridacna maxima f. elongata
(Mollusca, ~ivalvia). J. Zool. (London), 169 : 417-454.
Gwyther J. and ~Iunro J. L., 1981. Spawni ny i nducti on and reari ny
of larvae of tridacnid clams (~ivalvia, Tridacnidae).
Aquaculture, ~4: 197-217.
Hughes R.N. ,1977. The biota of reef flats and linlestone cliffs
near Jeddah, Saudi Arabia. J. nat. Hist., 2: 77-96.
Jameson S.C. ,1976. Early life history of the giant clams,
Tridacna crocea (Laillarck), T. maxima (Roding) ano Hippopus
hippopus (Linnaeus). Pacif. Sci., 30: 219-233 .
Jaubert J./ 1977. Light, nletabo lism and the distribution of
Tridacna maxirlla in a South Pacifie atoll: Takapoto (French
Polynesia). Proc. Third int. Coral Reef Syolp. l'dami, 1977:
489-494.
Jeffrey S.w. and Haxo F.l., 1968. Photosynthetic pigments of
symbiotic ainoflagellates (zooxanthellae) from corals and
clams. biol. bull., 135: 149-165.
La ~arbera M., 1975. Larval and post-larval developœent of the
giant clams, Trictacna maxirora ana Tridacna squamosa
(Bivalvia, Tridacnidae). l'iar . Hiol., ~: 233-23H.
",cKoy J.L., 1980 . ~iology, exploitation ana nranagerrlent of giant
cl ams (Tri aacni dae) in the k i ngdom of Tonga. Fi sh. Di v.
Tonga, Fish. Hull., 1: l-lb.
",cl'Iichael D.F., 1974. Growth rate, population size and mant le
coloration in the small giant clam, Tridacna maxima
(Roding) at One Tree Island, Capri corn Group, Queensland.
Proc. Second int. Coral Reef Symp. Brisbane, 1974, 1:
241-254.
489
f'lergner H., '1astaller ~,., 19bU. Ecol09Y of a reef lagoon are,
near Aqaba (Red Seal. Proc. Symp. coastl. mar. Environ.
ked Sea, Gulf Aden trop. west. Ind. Ocean.
J anuary 19HO, 2.: 39-70 .
Khartoum,
• ,unro J.L., Heslinga G.A., 19H3. Prospects for the cOlll"ercial
cultivation of giant clams (Uivalvia, Tridacnidael. Proc.
Gulf Carrib. Fish. Inst., 35: 122-133.
~,unro J. L., Gwyther J., 19!11. Growth rate ana maricultural
potential of tridacnid clams. Proc. Fourth int. Coral Reef
Symp. 'Manila, 1%1, 2: 633-636.
Munro J.L., Gwyther J.,(~,Sl. Growth of giant clams (Uivalvia,
Tri dacni dae l.
Oak ley S., 1984. The effects of fi shi n~ pressure on grouper
(Serran i aae l po pu 1 a t i ons in Eastern Rea Sea. Proc. SYII'p.
Coral keef lnviron. Rea Sea. Jeadah, 19H4:
Ricard ri., Salvat e., 1977. Faeces of Tridacna maxima (l',ollusca,
bivalvial, composition ana coral reef importance.
Third int. Coral Reef Syllip. ~lÎami, 1977: 495-5Ul.
Proc.
Richard G., 1977. ~uantitative balance and production of
Triaacna maxima in the Takapoto layoon (French Polynesial.
Proc. Thiro int. Cora l Reef Symp. Miami, 1977: 599-605.
Richard G., 1981" A first eva luati on of the findinys on the
growth and production of lagoon ana reef Mol l uscs in French
Polynesia. Proc. Fourth int. Co ral Reef SY'lip. Hanila,
1981, 3,: 637-641.
Nichara G., 19H2. Mo llusques lagunaires et rêcifaux ae Polyn~sie
fran~aise. Inventaire faunistique, biol1omie, bilan
quantitatif, croissance, pro~uction. Thesis (State
doctoratel,university of Paris VI, 313 p.
490
Kosewater J., 1965. The falllily Tridacnidae in the Indo-Pacific.
Indo-Pacific Mo llusca, 1 : 347 -396.
Salvat B., 1970. Les mo llusques des "récifs d'ilots" du récif
barrière des Iles Gambier (Polynés i e) . Hi onomie et densites
de peuplement. Bull. Nus. natnl. Hi s t . Nat., sir ie 2 ,
42(3): 525-542.
Salvat B. , 1971. Evaluation quantitative totale de l a faune
benthique de la bordure lagunaire d'un atoll de Polynésie
française. C.l(. Acad. Sc i . (Paris), sér ie D, 272: 211-214.
Salvat B., 1972. La faune benthique du l ago n de l'atoll de Reao
(Tuamotu,Polynesie) . Cah. Pac., ~: 30-1UH.
Yonge C.~I., 1936 . Mode of life, feea ing, digestion ana
symbionsis with zooxanthellae in the Tridacnidae. Scient.
l(ep. Grea t ba rri er Ree f Exped . 1928-1929, 1: 283-321.
Recommended