PertanikaJ. Trop. Agric. Sci. 28(1): 1 -11 (2005) ISSN: 1511-3701© Universiti Putra Malaysia Press

Morphology of Halophila ovalis (R.Br.) Hook. f.from Peninsular and East Malaysia

lANNALETCHUMY, L., ljAPAR SIDIK, B., 2MUTA HARAH, Z. & IARSHAD, A.lDepartment of Biology, Faculty of Science

Universiti Putra Malaysia, 43400 UPM Serdang, Selangor Darul Ehsan, Malaysia2 Faculty of Agriculture and Food Sciences,

Universiti Putra Malaysia Bintulu Campus, lalan Nyabau,P. O. Box 396, 97008 Bintulu, Sarawak, Malaysia

Keywords: Halophila, distribution, habitat characteristics, morphology

ABSTRAK

Halophila ovalis telah disampelkan dari enam lokasi yang mempunyai ciri habitat berbez.a; Merambong, lohordari Semenanjung Malaysia (beting sub-tidal), Teluk Sepinong, Sabah (muara sub-tidal), Pulau Gaya, Sabah(kawasan terumbu karang yang musnah) dan Merchang, Terengganu (inter-tidal danau air masin), TelukKemang, Negeri Sembilan (inter-tidal terumbu karang) dan Punang, Sarawak (pantai pasang surut). Berdasarkanpada dimensi daun (panjang dan lebar) dan bilangan pasangan urat daun, tiga jenis variasi H. ovalis dapatdibez.akan iaitu H. ovalis daun besar, sederhana dan kecil. Halophila ovalis daun besar dijumpai di kawasansub-tidal contohnya Merambong, Teluk Sepinong manakala H. ovalis daun sederhana dan kecil didapati dikawasan pasang surut yang terdedah pada udara selama 3 hingga 4 jam semasa air surut contohnya diPunang, Merchang, Teluk Kemang dan Pulau Gaya. Saliniti dan kedalaman air yang berbez.a untuk setiaphabitat yang menyumbang kepada perbez.aan bentuk dan dimensi saiz daun. Daun H. ovalis menunjukkanberbagai jenis bentuk dari ovate, obovate, oblong ke spatulate. Di kawasan yang lebih dalam, air yang keruh dantanah berlumpur, daun H. ovahs berbentuk lebih memanjang dan petiolnya juga panjang. Halophila ovalisdi Malaysia mempamerkan kepelbagaian morfologi terutamanya pada daun sebagai gerak balas pada faktorpersekitaran yang berbez.a di pelbagai habitat.

ABSTRACT

Halophila ovalis plants were collected from six locations with different habitat characteristics; Merambong, lohoreofPeninsular Malaysia (sub-tidal shoal), Teluk Sepinong of Sabah (sub-tidal estuary), Pulau Gaya, Sabah (sub­tidal degraded coral), Merchang, Terengganu (inter-tidal lagoon), Teluk Kemang, Negeri Sembilan (inter-tidaldegraded coral platform) and Punang, Sarawak (inter-tidal beach front). Based on the leaf dimensions (lengthand width) and number of paired cross-veins, three Halophila ovalis variants can be distinguished; big,intermediate and small-leaved. The big-leaved H. ovalis are found at sub-tidal areas e.g. Merambong, TelukSepinong, while intermediate- and small-leaved variants are from inter-tidal areas that are exposed to air for 3to 4 hours during low tides e.g. Punang, Merchang, Teluk Kemang and Pulau Gaya. The salinity and depthin a particular habitat contribute to the variability in shapes and dimension of leaf sizes. Halophila ovahs leavesshowed diverse shapes from ovate, obovate, oblong to spathulate. At deeper depths, turbid water and muddysubstrate, leaves of H. ovalis are elongated in shape and with longer petiole length. Halophila ovalis inMalaysia exhibit morphological variability particularly in the leaves in response to the different environmentalfactors in the various habitats.

INTRODUCTION

Malaysia has a total of 14 species seagrassesbelonging to 8 genera: Enhalus acoroides, Halophilabeccarii, H. decipiens, H. ovalis, H. minor, H.spinulosa, Thalassia hemprichii, Cymodocea rotundata,

C. serrulata, Halodule uninervis, H. pinifolia,Syringodium isoetifolium, Thalassodendron ciliatumand Ruppia maritima Uapar Sidik et al. 2001;Japar Sidik and Muta Harah 2003). Amongstthese species. H. ovalis exhibits morphology

ANNALETCHUMY, 1., JAPAR SIDIK, B., MUTA HARAH, Z. & ARSHAD A.

variability in response to different environmentalfactors at various habitats (den Hartog 1970;McMillan et al. 1983; Japar Sidik et aL 2001).According to den Hartog (1970), H. ovalis is a'collective species' consisting of a large array ofuncertain taxa. Examples of this are subspeciesaustralis (Doty and Stone 1966) den Hartog ofSouth Australia, subspecies lntllosa (Setchell) denHartog of Samoa, Tonga and Fiji, subspecieshawaiiana (Doty and Stone 1966) den Hartog ofHawaii and subspecies linearis (den Hartog) denHartog of Mozambique. Den Hartog (1970)categorised H. ovalis into subspecies based onthe leaf sizes and pairs of cross veins. Halophilaovalis has 12-25 pairs of cross veins, while H.minor has 4-12 pairs of cross veins. Observationson H. ovalis indicate that they have a wide rangeof leaf shapes and sizes, pairs of cross veins andpigmentation (Japar Sidik et aL 2001; Muta Harahet aL 2003). In addition, it was also reported thatH. ovalis has long petioles due to heavysedimentation and large shifts of sand by watermovements to obtain maximum sunlight andbig leaf blade due to less surface irradiancereaching the bottom of deeper depth, shadingor water turbidity reported at Merambong,Johore (Japar Sidik et al. 1999; Japar Sidik et aL2001). These are some responses of H. ovalistowards the ever changing and unstableenvironment. Other morphological variabilitiesrelated to environmental factors are also reportedby various researchers. Halophila ovalis with bigleaf blades are found under shaded environment(Duarte 1991), in brackish water (low salinitycompared to high salinity in marine waters)(Benjamin et aL 1999), low light due to depth(Beer and Waisel 1982; Longstaff and Dennison1999; Short et al. 2001; Ralph 1999) and muddysubstrate (Young and Kirkman 1975). Halophilaovalis with small leaves and short petioles arefound in habitats with hard carbonate substrate(coralline sand less in free nutrient, Short 1987).Changes in plant morphology and natural habitsin H. ovalis that is locally common certainlywarrant investigation. This paper reports on thedistribution, habitat characteristics andmorphology of H. ovalis.

MATERIALS AND METHODS

Halophila ovaliswere collected from six locations,comprising Merambong,Johore (01 0 19' 00"1030 36' 45" E), Merchang, Terengganu (050 02'15.0" , 1030 17' 53.0" E), Teluk Kemang, egeri

Sembilan (020 31' 00" , lOP 47' 00" E), TelukSepinong, Sabah (050 49' 3.42" N, 1180 09'14.28" E), Punang, Sarawak (1040 54' 23.6" N,1150 22' 36.3" E) and Pulau Gaya, Sabah (060

00' 11.0" , 1160 02' 30.4" E) (Fig. 1). At eachlocation, the environmental parameters wererecorded, e.g. substrate type, salinity, watertemperature and depth. In the laboratory, thecollected plants were cleaned of debris andsorted, e.g. vegetative structures comprising thelength and diameter of rhizome internode,length and width of leaf blades and petiolelength were measured using Mitotoyo DigitalVernier Caliper. Reproductive structures wererecorded digitally and measured: male flower­pedicel length, tepal length and width, andanther length and width; female flower-stylelength, ovary length and width and hypanthiumlength and length and width of fruit weremeasured using UTHSCSA Image Tool forWindows software (Wilcox et aL 1996). The wholestrand of the plants was recorded as digitalimages by using ikon CoolPix. The matureleaves were recorded as digital images and pairsof cross veins were counted from the recordedimages. The existing plant materials wereprocessed for herbarium specimens as describedby Menez et al. (1983) and some were preservedas wet specimens in 4% formalin in saline water.Leaf dimension data were analysed for varioushabitats and compared for differences orsimilarities by using Cluster Analysis using SPSSProgram version 12.0.

RESULTS AND DISCUSSION

Distrilnttions and Habitat Characteristics ofH. ovalis

The distribution of H. ovalis is shown in Fig. 1.Details of the habitat characteristics of H. ovalisare illustrated in Fig. 2 a - g showing; (i) inter­tidal degraded coral reef platform, e.g. TelukKemang (Japar Sidik and Muta Harah 2003;(ii) sub-tidal shoal e.g. Merambong; (iii) inter­tidal lagoon, e.g. Merchang; (iv) inter-tidal beachfront, e.g. Punang; (v) sub-tidal degraded coralreef flat, e.g. Pulau Gaya; and (vi) sub-tidalestuary, e.g. Teluk Sepinong. In the abovehabitats the waters depth varied from -1.0 to -5.0m MSL, temperatures between 25-34 QC andsalinity ranging between 29-31 psu (practicalsalinity unit). However, at the inter-tidal lagoonof Merchang, salinity fluctuated widely between9.41-34.41 psu. In addition, H. ovalis plants inMerchang can tolerate a wide fluctuation in

2 PERTANIKAJ. TRap. ACRIC. SCI. VOL. 28 NO.1, 2005

MORPHOLOGY OF H. OVALlS (R.BR.) HOOK. F. FROM PENINSULAR AND EAST MAlAYSIA

'"

"N

'ON

lOll Okm

111-X 103"1:

'"N

Habitat of H. ovalis at six locations in Malaysia:1. Lagoon, 2. Coral reef platform, 3. Sub-tidal shoal, 4.Inter-tidal, 5. Sub-tidal degraded coral and 6. Mangroveassociated

Fig.1: Distribution and six study locations: Peninsular Malaysia - Merchang, Terengganu;Teluk Kemang, Negeri Sembilan; Merambong shoal, Johore; Sarawak-

Punang and Sabah - PUlau Gaya; Teluk Sepinong

salinity resulting from freshwater input duringmonsoon and dry season respectively (Japar Sidiket aL 1999). Halophila ovalis were found to growand adapt themselves in various substrates fromcoralline sand, e.g. Pulau Gaya, sand coveredcoral, e.g. Teluk Kemang; calcareous sandy mud,e.g. Merambong; muddy loam, e.g. TelukSepinong to muddy sand, e.g. Merchang andPunang (Table 1). It was also noted that H.ovalis in certain locations e.g. at Merchang,Punang and Teluk Kemang could withstand 3-4hours exposure to air (den Hartog 1970).Halophila ovalis is a eurybiontic species that iscapable of surviving in very turbid and pollutedwaters. It was found in different places withdifferent ecological parameters. In clear water,H. ovalis distribution exceeded mid-tidal level to

nearly 60 m in depth on substrates ranging fromsoft mud to coarse rubble (den Hartog 1970;Hillman et al. 1995).

Fig. 2: The habitat of H. ovalis andenvironmental characteristics around coastalwaters of Malaysia; (a) Teluk Kemang (inter­tidal, degraded coral reef flat), (b) Merambong(sub-tidal, unexposed), (c) Merambong (sub­tidal, exposed), (d) Merchang (inter-tidallagoon), (e) Punang (inter-tidal beach front),

(f) Pulau Gaya (sub-tidal, degraded coral reef)and (g) Teluk Sepinong (sub-tidal estuary).

Halophila ovalis Variants

Cluster analysis interpretation (Fig. 3) based onthe leaf size dimension (leaf length and width)and pairs of cross veins distinguished H. ovalisinto three categories: big-leaved, intermediate­leaved and small-leaved variants (Plate 1). TelukKemang (exposed), Pulau Gaya and Merambong(exposed) exhibit the small-leaved variants whilethe intermediate-leaved variants are fromMerchang and Punang. The big-leaved variantsare from Merambong (sub-tidal shoal, unexposed)and Teluk Sepinong (sub-tidal estuary)respectively. The details of vegetative structuressuch as leaf length and width, petiole length,rhizome internode length and diameter, pairs ofcross veins are given in Table 1. Big-leaved H.ovalis plants were found mostly in a shadedenvironment, e.g. Merambong or in areas withlight limitations, e.g. Teluk Sepinong. The big­leaved variants of Merambong were foundgrowing under the shade of tall Enhalus acoroidescanopy and found fully submerged even duringthe lowest tide level (Fig. 2b). The big-leavedvariants from Teluk Sepinong are adapted to

PERTANIKAJ. TROP. AGRIC. SCI. VOL. 28 NO.1, 2005 3

"'" TABLE 1Habitat characteristics and vegetative structure characteristics (measurement given as mean ± standard error and range) of big-leaved,

intermediate-leaved and small-leaved H. ovalis from the six locations. Number in parenthesis is the number of samples

Habitat characteristics Dimensions of vegetative structures

Associated Substrate Salinity Water Depth Leaf length Leaf width Petiole Rhizome Diameter Pairs of

~habitat type psu temperature (m MSL) (mm) (mm) length internode of rhizome cross-vein(0C) (mm) length (mm) internode counts

~(mm) tT1>-l

'"I:l (")tT1 Big-leaved :r:Ej c:

~Merambong, Sub-tidal Calcareous 29.6-30.7 29.0-31.0 2.0-2.7 23.7±O.18 13.7±O.11 20.8±O.30 23.86±O.40 0.98±O.03 14.24±O.06

-~johore shoal, muddy sand 10.29-36.46 5.66-32.18 12.38-46.91 4.72-55.21 0.54-1.67 10-21~ unexposed (761) (763) (753) (656) (179) (1467) .r

':- l>-l Teluk Sepinong, Sub-tidal Muddy loam 28.0-31.0 28.0-29.0 2.0-2.7 20.8±O.56 12.81±O.29 27.8±O.80 24.27±O.96 1.07±O.04 16±O.23~ Sabah estuary 5.52-35.83 5.09-20.89 12.41-66.94 1.58-54.02 0.54-1.58 11-22'"I:l en

~(129) (126) (129) (127) (40) (208) S

71~ Intermediate-leaved p'(")

Punang, Sarawak Inter-tidal- Muddy sand 20.0-31.0 25.0-34.0 1.5-2.7 19.7±O.18 8.98±O.09 29.03±O.42 24.56±1.50 0.89±O.05 14.48±O.20en~p beach front 16.29-23.10 7.09-10.57 21.57-41.21 7.18-43.26 0.60-1.25 12-18 C-< (76) (132) (129) (138) (88) (144) ~0

r

-~N> Merchang, Inter-tidal Muddy sand 9.41-34.41 29.0-30.1 1.0-2.0 17.24±O.18 7.82±O.09 25.1±O.42 12.15±O.38 0.87±O.02 12.64±O.0700

Z Terengganu lagoon 10.2-24.70 4.62-13.35 10.73-51.98 3.24-26.96 0.43-1.25 8-189 (255) (260) (293) (199) (73) (460).:-- ~N> Small-leaved R"00

Merambong, Sub-tidal Calcareous 29.6-30.7 29.0-31.0 2.0 11.36±O.09 6.54±O.05 13.79±O.23~

(J1 11.28±O.14 0.60±0.019 9.78±O.06johore shoal, sandy mud 6.68-15.89 3.56-9.65 2.31-23.44 2.6-27.00 0.16-1.47 7-15

exposed (553) (581) (616) (554) (117) (1150) ~Pulau Gaya, Sabah Sub-tidal Coralline 29.0-31.0 30.0-32.0 1.5-2.5 8.19±O.12 5.47±O.07 10.6±O.23 11.76±O.26 0.8±O.02 9.66±O.07 ?>

degraded sand 2.08-14.03 2.21-9.31 8.41-26.95 1.12-36.11 0.33-1.44 6-16coral (474) (475) (505) (803) (113) (1033)

Teluk Kemang, Inter-tidal; Sand 29.0-31.0 28.0-31.2 1.0-2.0 13.1±O.17 7.14±O.07 11.03±O.25 16.2±O.31 0.85±O.01 1O.91±O.06Negeri Sembilan degraded covered coral 5.11-21.01 3.10-11.89 5.01-27.31 3.18-39.92 0.48-1.39 8-15

reef flat (473) (473) (425) (541) (136) (806)

MORPHOLOGY OF H. aVAilS (R.BR.) HOOK F. FROM PENINSULAR AND EAST MALAYSIA

SargassumReef platform

~--­;::.'\\

Padina sp. H. ova/is"Sand covered coral

(a)

2.0 - 2.7 mMSL

(b)

!2.0 - 2.7 mMSL

(c)

Muddy sand

(d)

PERTANIKAJ. TROP. AGRIC. SCI. VOL. 28 NO.1, 2005 5

ANNALETCHUMY, L., JAPAR SIDIK, B., MUTA HARAH, Z. & ARSHAD A.

Wet monsoon season

sandy mud

(e)

2.0 mMSL

2.0 mMSL

(f)

120 mMSL

(9)

Fig. 2: The hamtat ofH. ovalis and environmental characteristics around coastal waters of Malaysia:(a) Teluk Kemang (inter-ticlal, degraded coral reef flat); (b) Merambong (sulrtida~ unexposed);

(c) Merambong (sulrtidal, exposed); (d) Merchang (inter-tidal lagoon); (e) Punang(inter-tidal beach front); (j) Pulau Gaya (sulrtidal, degraded coral reef);

and (g) Teluk Sepinong (sulrtidal estuary)

living in a dark water environment which limitslight penetration. Halophila ovalis plants thatgrow in degraded corals or in areas exposed toair have intermediate and small-leaved variants.The intermediate-leaved variants from Punang(inter-tidal beach front) and Merchang (inter­tidal lagoon) were observed to be under a widerange of salinity fluctuations. The small-leavedvariants are found in degraded coral substrate,e.g. Pulau Gaya, in exposed areas e.g.Merambong or exposed degraded coral substrate,e.g. Teluk Kemang. McMillan (1983) reportedthat in Halophila, substrate types also correlatedwith leaf size dimension; small-leaved plants came

from firm silty substrate while the large-leavedplants are from muddy calcareous sand which isalways covered with water. In this study, big­leaved variants were found to be growing on thecalcareous sandy mud substrate, e.g. atMerambong. Though small-leaved variants growon the same substrate type, these plants havesmall leaves in response to the unfavorableenvironmental condition, i.e. they are exposedto air for a period of 3-4 hours during the lowtide Qapar Sidik et at. 2001). The intermediate­leaved variants from Merchang and Punangexhibit purplish blotches or dots on the leaves(Plate 2d) and the Teluk Kemang small-leaved

6 PERTANIKAJ. TROP. AGRIC. SCI. VOL. 28 O. 1,2005

MORPHOLOGY OF H. OVAllS (R.BR.) HOOK. F. FROM PENINSUlAR AND EAST MALAYSIA

Euclidean Distance

Num +---------+---------+---------+---------+---------+T,Mannnso 5 10 15 20 25

Merambong, exposed 5

Teluk Kemang 7

Pulau Gaya 4

Punang 3

Merchang 6

Merarnbong, unexposed 1

Teluk Sepinong 2

Small-leaved variant<;

Intermediate-leaved variants

Big-leaved variants

Fig. 3: Hierarchical Cluster Analysis using leaf size dimensions (leaf length,leaf width) and cross veins ofH. ovalis from six locations. The similar size

leaf blades and cross veins were grouped by Euclidean Distance

variants have pinkish pigment on the petiolenear the base of the leaf (Plate Ie). These areresponses to the high light conditions duringexposure to air (Japar Sidik et aL 2001) and arebelieved to be UV-blocking pigments (Hemmingaand Duarte 2000).

Leaves of H. ovalis at each habitat showeddiverse shapes from ovate, obovate, oblong tospathulate. At deeper depths, turbid water andmuddy substrates, e.g. Merambong (sub-tidalshoal, unexposed), Teluk Sepinong (sub-tidalestuary) the leaves of H. ovalis were elongated inshape and with longer petiole length (Plate 1a &1b, Plate 2a & 2b). At shallower depths, clearwater and coral sand, e.g. Pulau Gaya, TelukKemang, and Merambong (exposed) theHalophila leaves were more ovate to obovate inshape and with a short petiole length (Plate Ie,1f & 19, Plate 2e, 2f & 2g). However, in exposedareas and muddy sand, the leaves of H. ovaliswere oblong and spathulated with pointed apexand with long petiole length in response tolarge shifts of sand from the rivers (Plate 1b &Ie, Plate 2c & 2d).

The least number of pairs of cross veins (6-16) were in small-leaved variants for TelukKemang, Merambong and Pulau Gaya, 8-18 forPunang and Merchang, while the Merambongbig-leaved plants had 10-22 pairs of cross veins.In the previous studies, the number of pairs ofcross veins of H. ovalis big-leaved was in therange ofl0-25 as reported by den Hartog (1970);12-25, (Sachet and Fosberg 1973) and 10-25(Kuo 2000). The range in number of pairedcross veins counts for the small-leaved Halophila

populations were found to overlap with those ofH. ovalis and H. minor. Based on Kuo (2000), H.minor posses 7-12 pairs of cross veins and H.ovata 4-12 pairs of cross veins, while according toden Hartog (1970) H. minor (Zoll) has 5-9 pairsof cross veins. In the present study, the small­leaved Halophila could be placed in the categoryof either H. ovalis or H. minor. To confirm thetaxonomic uncertainty, a study on both variantsshould be conducted in culture conditions.

Reproductive Structures

Reproductive structures, male and female flowersand fruits were observed at a coastal lagoonarea, Merchang; in exposed sub-tidal area,Merambong; and in an inter-tidal area, Punang.However, at Punang only opened male flowerswere observed. Comparatively, the male flowerof Punang had longer pedicel and anther lengthcompared to those from Merchang andMerambong (Table 2). Den Hartog (1970)reported that female flowers had three styles, 10­20 mm long, ovary ovoid, 1-1.5(-2.5) mm long,and a hypantium of 3-5 mm length. Male flowershad tepals 3 which were mm long and 2 mmwide and a 10-20 mm long pedicel. For H. minor(Kuo 2000), the male and female flowers weresmaller than Halophila ovalis in Merchang,Merambong and Punang, while the styles andhypantium were long, 4.99-21.79 mm and 1.17­6.61 mm.

CONCLUSION

1. Halophila ovalis in Malaysia exhibitsmorphological variability in response to the

PERTANIKAJ. TROP. AGRIC. SCI. VOL. 28 NO.1, 2005 7

ANNALETCHUMY, L., JAPAR SIDIK, B., MUTA HARAH, Z. & ARSHAD A.

TABLE 2Measurement (as ranges in mm) of the reproductive Structures of H. ovalis from Merambong, lahore,

Merchang, Terengganu and Punang, Sarawak. is the number of samples, nd = not observed

Reproductive structure

Male flowerPedicel lengthTepal lengthTepal widthAnther lengthAnther width

Female flowerStyle lengthOvary lengthOvary widthHypanthium length

FruitFruit lengthFruit width

Merchang, Terengganu.

=60.78-14.58

3.46-4.71.38-2.312.67-3.821.29-1.69

=65.23-21.790.83-1.421.65-5.971.07-5.97

=31.25-3.340.82-2.58

Merambong, Johore.Inter-tidal, lagoon

Muddy sand

N=40.73.161.843.031.6

N=64.99-18.510.99-1.770.67-1.221.17-6.61

=4(1.93-3.82)(1.28-2.5)

Punang, Sarawak.Sub-tidal Inter-tidal,

Calcareous sandy mudMuddy sand

N=51.11-14.983.7-3.91

1.79-2.223.4-4.451.38-1.66

ndndndndnd

ndndnd

different environmental factors in the varioushabitats. Such responses are reflected in the leafsizes and shapes. Halophila ovalis can bedistinguished into three categories; big-leaved,intermediate-leaved and small-leaved variants.The big-leaved variants, e.g. at Merambong(unexposed sub-tidal) and Teluk Sepinong (sub­tidal estuary) in response to shaded conditionsand light limitations have longer leaf length,petiole length, higher number of paired crossveins and are elongated in shape. Theintermediate-leaved H ovalis, e.g. from Merchang(inter-tidal lagoon) and Punang (inter-tidal beachfront) were under exposure to air during lowtide and in an environment of wide salinityfluctuation. Small-leaved H ovalis from PulauGaya (sub-tidal degraded coral), Merambong(exposed sub-tidal) and Teluk Kemang (inter­tidal degraded coral reef flat) have relativelysmall leaves compared to the intermediate-leavedand big-leaved variants. They are observed eitherfrom shallow areas or exposed to air for a periodof 3-4 hours during low tide.

2. The paired cross veins counts for thesmall-leaved Halophila populations show rangesthat overlap with those of H ovalis and H minor.The small-leaved Halophila plants can be placedin either the category of H ovalis or H minor.To confirm the taxonomic uncertainty, a study

on both variants should be conducted in cultureconditions.

REFERENCES

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BENJAMIN, K]., D.1. WALKER, AJ. MCCOMB and].Kuo. 1999. Structural responses of marineand estuarine plants of Halophila ovalis (R.Br.) Hook. j to long term hyposalinity.Aquatic Botany 64: 1-17.

DEN HARTOG, C. 1970. The Sea Grasses of the World.Tweede Reeks, Deel 59, No. 1. Amsterdam,London: orth-Holland PublishingCompany.

DoTY, M.S. and B.C. STONE. 1966. Two new speciesHalophila (Hydrocharitaceae). Brittonia 18:303-306.

DUARTE, C.M. 1991. Seagrass depth limits. AquaticBotany 40: 363-377.

HEMMINGA, M.A. and C.M. DUARTE. 2000. SeagrassEcology. Cambridge: Cambridge UniversityPress.

HILLMAN, K, AJ. McCOMB and D.1. WALKER. 1995.The distribution, biomass and primary

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MORPHOLOGY OF H. aVAilS (R.BR.) HOOK F. FROM PENINSULAR AND EAST MAlAYSIA

(a)(b)

11 em

(c)

11 em

(e) (f) (g)

Pwte1: Cluster Analysis; a- lJig-leaved H. ovalis from Merambong, unexposed sub-tidal shoal; b- lJig-leaved H. ovalisfrom Teluk Sepinong sub-tidal estuary; c- Intermediate-leaved H. ovalis from Punang, inter-tidal beach front; d­

Intermediate-leaved H. ovalis from Merchang, inter-tidal wgoon; e, f, g- smaU-leaved H. ovalis from Teluk Kemang,inter-tidal coral reef flat, Merambong, sub-tidal exposed and Puwu Gaya, sub-tidal degraded coral reef respectively

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ANNALETCHUMY, L., JAPAR SIDIK, B., MUTA HARAH, Z. & ARSHAD A.

(a) (b)

1 em

(c) (d)

(e) (f) (g)

10

Plate 2: Category ofH. ovalis based on leaf sizes and shapes; a, b - big-leavedH. ovalis-ovate, oblong to spathulate; c, d - intennediate-leaved H. ovalis-ovate,

oblong with pointed apex and e, f, g - small-leavedH. ovalis-round, ovate to obovate

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(Received: 25 February 2005)(Accepted: 8 September 2005)

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