MOLLUSCS COMMUNITY IN.BATANG KAYAN ESTUARY,

LUNDU, SARAWAK

Abang Azizil Fansuri Bin Abang Abdullah

QL 413 A1l7

Bachelor of Science with Honours1011 (Aquatic Resource Science and Management)

20 It

PUSlt KbidlDlt Maklumat Akademik UNIVERSm MALAYSIA SAKAWAK

Molluscs Community in Batang Kayan Estuary, Lundu, Sarawak

P.KHIDMAT MAKLUMAT AKADEMIK

11111 III 1IOimll 1111111 1000235669

Abang Azizil Fansuri Bin Abang Abdullah

This project is submitted in partial fulfillment of

The requirements for degree of Bachelor of Science with Honours

(Aquatic Resources Science and Management)

F ACUL TY OF RESOURCE SCIENCE AND TECHNOLOGY

UNIVERSITI MALAYSIA SARA W AK

2011

ACKNOWLEDGEMENT

Alhamdulillah, my appreciation to Allah for giving me a change to completed this project

on time. First of all, I would like to say my thanks to my parents which give me all the

support and love that I needed the most especially during the hard time. I am greatly

indebted to my supervisor, Prof. Dr. Shabdin Mohd Long for introducing me into the world

of Molluscs and also for his support and guidance until the end of my final project.

I am thankful to the FRST's lab assistant, Mr. Richard Toh and Mr. Zaidi Ibrahim for their

helping hand to help me during preparation of the equipment and the collection of my

samples and also value their professionalism during working together. Thank you also to

my friend, Harold Tinggang Ngau, Asmyrita Husna binti Ahmad, Siti Nur Sakinah binti

Zainuddin, as we have been working together under Prof. Dr. Shabdin Mohd Long.

Also not forgotten to our senior Cheng Chen Ann and Nur Atiqah binti Mohamad Yussof

as their guide me during laboratory work and in doing this thesis. I would like to thanks to

my third years course mate Aquatic Resources Science and Management for their support

to me during making this project. Lastly I would like to thanks to anyone who have helped

me during making this project until complete whether direct or indirect help .

...

II

DECLARATION

[ hereby declare no portion of the work referred to in dissertation has been submitted in

support of an appJ ication for another degree of qualification of this or any other university

or institution of higher learning.

I

ABANG AZIZIL F ANSURl BIN ABANG ABDULLAH

Aquatic Resource Science and Management

Faculty of Resource Stience and Technology

Universiti Malaysia Sarawak

III

Pusat Khidmat Maldumat Akademik UNtVERSm MALAYSIA SARAWAK

TABLE OF CONTENTS

Contain Page

Title & Front Cover ..................................... ... .................. ... ........ .

Acknowledgement ..... ........ ....... .............. ............. ..... ............. ....... II

Declaration ................................................................................. III

Table of Contents............................................................. .. .......... IV

List of Abbreviations ... .................. .. .................. ... ................. ..... ... VII

List ofTables .... .................. ........................................................ VIII

List of Figures .......................................................................... .... IX

Abstract ..................................................................................... X

1.0 Introduction ........................................................................... .

2.0 Literature Review.................................. ... ................... ..... ... ..... 4

2.1 Molluscs Habitat in The Mangrove Ecosystem............................ 4

2.2 Classification of MoBuscs ...............;.................................. ... 5

2.3 Feeding Habits........ .. ........................................................ 6

2.4 Molluscs as Pollution Indicators............................................. 6

2.5 Molluscs Distribution in Borneo............................................. 7

2.6 Diversity Indices ............................................................... 8

3.0 Materials and Methods....................... ........ ............ . ................... 9

3.1 Study Area...... .............................................................. ... 9

3.2 Species Distribution Along The Estuary..... .. ... .......................... I I

3.3 Species Zonation From High Tide Level to Low~r Tide Level.......... II

3.4 Molluscs Zonation on The Tree Trunk ...................................... II

3.5 Physico-chemical Parameter ofThe Water......... .. ................. ..... 13

3.6 Preservation ... ...................................... ... ......................... 13

3.7 Species Identification..... .......... ... . . .... . .................. ............... 13

3.8 Sediment Analysis.... ...... ............................... .. ...... .......... ... 13

3.9 Laboratory Work ................................................................ 14

IV

_.:

,..... ,

3.9.1 Total Organic Matter ................................................ . 14

3.9.2 Chlorophyll a... .. . .................... .... ............... .. .... .. ............ . 14

3.9.2.1 Water Contain in Sediment (damp) ........................... . 15 d

3.10 Data Analysis ................................................................. . 15

3.10.1 Shannon-Weiner Index ....................... ...................... . 16

3.10.2 Pielou's Evenness Index ........................................... . 17

3.10.3 Richness ............................................................. .. 17

3.10.4 Density .............................................................. .. 17

3.10.5 Correlation ........................................................... . 18

4.0 Results ................................................................................. .. 19

4.1 Field Trip ....................................................................... .. 19

4.2 Survey of Molluscs Along Batang Kayan, Sarawak ...................... . 19

4.2.1 Physico-chemical Parameters ...................................... . 20

4.2.1.1 pH ............................................. .. ............ .. 20

4.2.1.2 Temperature ................................................. . 20

4.2.1.3 Dissolved Oxygen ......................................... .. 21

4.2.1.4 Turbidity ..................................................... . 21

4.2.1.5 Salinity .................... .. ......., .......................... . 21

4.2.2 Species Composition .........: ..................................... .. 25

4.2.3 The Distribution of Molluscs ...................................... .. 27

4.2.4 Species Diversity . . .................... . .................... . ........ .. 27

4.3 Horizontal Species Zonation Distribution From High Tide to Low

Tide Level. . ............................. . ..................... .. ............... . 30

4.3.} Line Transect 1 ....................................................... . 30

4.3.1.1 Chlorophyll a ...................... .. ...... '" ............ ... ..... .. 30

4.3.1.2 Total Organic Matter ...................................... .. 30

4.3.1.3 The Species Composition ofM911uscs ................... . 33

4.3.1.4 The Horizontal Distribution (zonation) of Molluscs .. .. 34

4.3.15 Species Diversity ...... :..................................... . 35

4.3.2 Line Transect 2 ................... . . . .................................. 38

4.3.2.1 Chlorophyll a ..................... .................... . ........... .. 38

4.3.2.2 Total Organic Matter ...................................... .. 38

4.3.2.3 Species Density .............................................. . 40

v

_ ,T"

I

4.3.2.4 The Horizontal Distribution (zonation) of MoIIuscs.. ... 42

4.3.25 Species Diversity......................................... .... 42

4.4 Vertical Zonation of Molluscs................................................ 45 ::.~

4.4.1 Zone I ....................... ..... ..................................... . 45

4.4.2 Zone 2 .................................................................. 45

4.4.3 Zone 3 .................................................................. 46

4.4.4 Zone 4 .................................................................. 46

4.5 Correlation Analysis.................................. ... ...................... 48

4.5.1 Along the Batang Kayan Estuary................................... 48

4.5.2 Line Transect 1.................................................... ..... 48

4.5.3 Line Transect 2 ............. .... ...................................... 48

4.6 Gastropod and Bivalve Molluscs in Batang Kayan ....................... 50

5.0 Discussion...................................................... .. ..................... 51

5.1 Molluscs Community in Batang kayan .................... ................. 51

5.1.1 Gastropod Communities in Batang Kayan ......................... 53

5.1 .2 Bivalve Communities in Batang Kayan ............................ 53

5.2 The Occurrence of the Molluscs along the Batang Kayan River........ 55

5.3 The Occurrence of molluscs for vertical zonation........................ 55

5.4 The physico-chemical parameters ........................................... 56

5.5 The relationship between molluscs and physico-chemical parameters.. 57

6.0 Conclusion.................................. ............ ................................ 59

7.0 References ............. ...................... ........ ............ ......... ....... ....... 60

8.0 Appendices .. ........... ............... ...... ....... ............. . ............ .... ...... 64 w'

VI

r I

I,

Abbreviation

%

DO

SPSS

TOM

rpm

Nm

GPS

N

E

mg/ I

NTU

PSU

Ind. / m 2

mg/m3

g

m

cm

LIST OF ABBREVIATIONS

Description

Percentage

Dissolved Oxygen

Statistical Package for Social Science

Total Organic Matter

Round per Million

Nanometer

Global Positioning System

North

East

Miligram per Liter

Nephelometric Turbidity Units

Practical Salinity Units

Individual per one meter square

MiIligram per Cube

Gram

Meter

Centimetre

VII

I

LIST OF TABLES

Number

Table 1: The classes, examples and defining characteristic of phylum Mollusca '"' 5

Table 2: Coordinate of the sampling station along the Batang Kayan, Sarawak 19

Table 3: The mean and standard deviation (SO) ofphysico-chemical parameters 22

Table 4: List of species name, total number, percentage abundance (%) and the 25

density (lnd.l m2) along the Batang Kayan Estuary

Table 5: List of number of individual, total number of individual, Shannon 28

Diversity Index (H'), Pielou's Evenness Index (J) and Margalef

Richness Index (Of) for along Batang Kayan estuary.

Table 6: Mean and standard deviation of chlorophyll a and total organic matter 31

for line transect 1

Table 7: List of species name, total number (Ind. / m2 ), abundance percentage 33

(%) and the density (Ind. / m2) for line transect 1

Table 8: List of number of individual, total number of individual, Shannon 36

Diversity Index (H'), Pielou's Evenness Index (J) and Margalef

Richness Index (Of) for line transect 1

Table 9: Mean and standard deviation for chlorophyll a and total organic matter 39

for line transect 2

Table 10: List of species name, total number (Ind. /0.25 m 2), abundance 41

percentage (%) and the density (Ind. / m2 ) for line transect 2

Table 11: List of number of individual, total number of individual, Shannon 43

Diversity Index (H'), Pielou's Evenness Index (J) and Margalef

Richness Index (Of) for line transect 2

Table 12: The occurrence of molluscs at each tree 46

Table 13: Correlation between physico-chemical with Shannon Index 49 ,;

Table 14: Correlation between chlorophyll a (ChI a) and total organic matter 49

(TOM) with Shannon Index, Evenness Index and Richness Index at

line transect 1 and 2

Table 15: Strength of correl'ation 49

Table 16: List of gastropod and bivalve in Batang Kayan Estuary 50

VIII

MOLLUSCS COMMUNITY IN BATANG KAYAN ESTUARY, LUNDU,

SARAWAK

Abang Azizil Fansuri Bin Abang Abdullab

Aquatic Resource Science and Management Faculty of Resource Science and Technology

Universiti Malaysia Sarawak

ABSTRACT

The study was designed to determine the molluscs community in mangrove area which included the composition, distribution, zonation and water quality parameters. The survey was conducted in mangrove area at Batang Kayan Estuary, Lundu, Sarawak on October 20 I O. The survey mainly used line transects and quadrate method. The main group of molluscs identified was Gastropods and Bivalve. There a total of eleven families which consist of twenty one species. Along the Batang Kayan there are seven families consist of fourteen species. The first line transect there are five families consist of seven species and the second line transect there are four families consist of 6 species. While for the vertical zonation there are 6 families consist of 6 species. There weak correlation of water quality parameter for Station along Batang Kayan. For line transect, there are strong correlation of chlorophyll a at transect two but weak correlation with total organic matter same with transect one. The might be other factors that dominant in influence the community of molluscs such as types of substrate.

Key words: Mangrove area, molluscs community, line transect, gastropod and bivalve

ABSTRAK

Kajian ini dijalankan untuk menententukan komuniti molluska di kawasan paya bakau yang meliputi komposisi, taburan, zonasi dan parameter kualiti air. Kajian ini dijalankan di kawasan paya bakau yang terletak di Muara Batang Kayan, Lundu, Sarawak pada bulan Oktober 2010. Kajian ini mengunakan kaedah transek and kuadrat. Kumpulan utama yang dikenal pasti adalah Gastropoda and Bivalvia. Terdapat dua puluh satu spesies mollusks yang terletak di dalam sebelas Jamili. Di sepanjang Sungai Batang Kayan dapat dijumpai empat belas species terletak dalam tujuh Jamili. Manakala untuk transek satu terdapat tujuh species berasal dari lima spesies dan transek dua pula ada enam spesies berasat dari empat Jamili. Selain itu, untuk zonasi menegak dapt dijumpai enam Jamili yang mengandungi enam species. Terdap~t bacaan korelasi yang lemah di antara parameter kualiti air di sepanjang Sungai Batang Kayan tetapi terdapat korelasi yang kuat di transek dua. Daripada bacaan korelasi dapat dinyatakan bahawa kemungkinan terdapat Jaktor lain yang lebih mempengaruhi komuniti molluska sperti jenis substrat.

Kala kunci: Kawansan paya bakau, komuniti molluska, transek, gastropoda dan bivalvia.

x

1.0 INTRODUCTION

1.1 Overview

Linnaeus was the first person to use 'Mollusca' in 1757. According to Pechenik (2005),

phylum molluscs has three defining which are dorsal epithelium forming mantle,

cuticular band if teeth (radula) and ventral body wall muscles develop into a

locomotory or clinging foot. The phylum of Mollusca can be divided into seven

classes, which are Polyplacophora, Aplacophora, Monoplacophora, Gastropoda,

Bivalvia, Cephalopoda and Scaphopoda (Pechenick, 2005). Gastropods and bivalves

constitute 98 % of the total population of mollusca and inhabit land, freshwater and

marine environments (Ruppert et aI., 2004).

Sarawak is located in Southeast Asia. Sarawak is the largest state in Malaysia which it

consist of large diversity of tropical rainforest. Sarawak covers 26 % of the total

mangrove area in Malaysia where in 2000 it is estimated about 570,000 ha (Giesen et

al., 2007). The mangrove forests in Sarawak cover above 173,790 ha (1.4 %) of the

total Sarawak land area and Batang Kayan Estuary was included in the mangrove area

(Wan, 2010). The Batang Kayan was estimate about 1711 km2 for the total areas.

While for the total length of Batang Kayan was 125 km. The Batang Kayan water can

be considered polluted recorded in the annual report by the Natural Resource and

Environmental Board report Batang Kayan fall in clas~ lIB (NREB, 2004).

Mangroves represent the dominant soft bottom plant communities of the marine

terrestrial transition in tropical and subtropical regions. The plant species can be

consider as one of the members of the terrestrial families which have ability to survive

under the hazard conditions such as of high salinity, low oxygen and nutrient

availability in the soil, wind and wave action, and substrate instability (Perreta, 1993).

Estuaries are unique and important ecosystem with significant economic values. The

brackish water and the tidal range create an environment that are div1ing the freshwater

from the ocean and the organisms that live in these habitats are permanendy exposed to

stressful condition. The macro invertebrates is one of the communities that live in the

harsh condition of estuarine. Some of this community distribution and abundance

mostly related to the factors that influence the diversity such the abiotic and change

with the physical surroundings (Menke et al., 2007).

The animals also like the plants where it representatives of largely terrestrial groups. In

contrast the aquatic animal community is dominated by members of essentially marine

families which are adapted to variable salinity, turbid conditions and to feeding directly

or indirectly on materials from the dominant primary products (Perreta, 1993).

From the previous study, the molluscs community are focused on Bako National Park

which studied by Johari (1997) and Shahidatul (2007). Recent study on molluscs

community also been carried out in Asajaya mangrove forest by Wan (2010). However

there are still less information on molluscs community at Batang Kayan Estuary.

Therefore this research aimed to collect, examine and identify the existing molluscs

fauna and also to determine the distribution and density of each of molluscs as well the

influence of physico-chemical parameters in the areas on the molluscs community. The

hypothesis for this study is the diversity of the molluscs species may be influence by

the source of food and the condition of the water in Batang Kayan.

2

1.2 Objectives

The objectives of this study are i) to study the species composition of gastropod and

bivalves in the estuary, ii) to determine the gastropod and bivalves distribution in

Batang Kayan River Estuary iii) to determine the species diversity of gastropods and

bivalves in the estuary and iv) to determine the influence of the physico-chemical

parameters of the water on molluscs community .

.'

3

,....

2.0 LITERATURE REVIEW

2.1 Molluscs Habitat in Mangrove

The habitat can play an important role in determining the distribution of molluscs

(Ahmad, 1991). Molluscs can be found in the mangrove, rocky or sandy beach.

According to Ahmad (1991), the tidal area is the place where the most suitable place to

show various species of molluscs in the area. For example the Patella and Pho/as more

prefer sandy beach as it habitat to live while Natica and Donax prefer rocky area.

Animal in the class of bivalve usually can be found in the mangrove area. This is due

the mangrove area consist of organic material which support invertebrate and flora

which be used by the molluscs as its food. The mangrove area usually consist of

molluscs in the class of gastropod and bivalve such Ba/ananus, Amphitrite, Saccostrea

and Murex capucinus which found stick to the tree trunks (Ahmad, 1991). According

to Wan (2010), the abundance of molluscs in certain area is influenced by the amount

of dissolved calcium in the water. This is due to the presence of the calcium which an

essential constituent of the shell. Mangroves are known to provide important nursery,

breeding and foraging grounds and structural habitat for shelter from predators for

mollusc community (Clarke & Johns, 2002). According to Pechenik (2005), the

gastropoda is the largest molluscan class whereby half of all the living mollusc species

fall in this class. The gastropod that represent in this class is snaits, whelks, limpets,

slug and many more which can be call as epifaunal species. For the bivalves, outer

.' shell consists of two pieces or valves (Kenneth,. 2007). The bivalves prefer in the

habitat where the waters with gravely, sandy or muddy bottom where it can partly

buried. The bivalve can be found at the fast flowing scours the stream beds (Wan,

2010).

4

Pusat Khidmat Makl mat Akademik UNIVERSm MALAYSIA SARAWAK

2.2 Classification of Molluscs

The shell and the radula is the main structure to characterize a species and make it as a

main structure in the classification of phylum molluscs (Shabdin & Rosl'liza, 2010).

According to Pechenik (2005), the seven classes of molluscs are recognized based on

morphology of the food and the presence or absence and type of shell. All seven

classes of molluscs are present in the sea but some bivalve and gastropod are found in

freshwater habitats too (Ruppert et al., 2004). Only the gastropods are present on the

land. Table 1 shows the classes, examples and defining characteristic of phylum

Mollusca.

Table 1: The classes, examples and defining characteristic of phylum Mollusca (Pechenik, 2005)

Classes and Examples Defining Characteristics

Polyplacophora (Chiton) Shell fonns as a series of 7 to 8 separate plates

Aplacophora Cyrindrical, venniform body with the foot fonning a

(Solengasstres) narrow keel

Monoplacophora (Limpet) 3 to 6 pairs of ctenidia, 6 to 7 pairs of nephridia

Multipl~ pairs of foot retractor muscles.

Gastropoda (Snail) Visceral mass and nervous systems become twisted

90-180° during embroyonic development

Proteinaceous shield on the foot

Bivalvia ( Clam) Two-valved shell

Body flattened laterally

Scaphopoda Tusk-shaped, conical shell, open both ends

Development of anterior, threadlike, adhesive feeding

tentacles.

Cephalopoda (squid) Shell divided by 'septa, with chambers connected by

the siphuncle

Closed circulatory system

Foot modified to fonn flexible arms and siphon

Ganglia fused to fonn a large brain encased in

cartiginous cranium.

5

2.3 Feeding Habit

Food is one of the factors that influence the structure of the shell of phylum Mollusca

(Shabdin & Rosniza, 2010). The environment which full with the source of food for the

phylum molluscs will help the growing of the shell and also make it become thick, full

with color and column with the mollusca less food source. The molluscs need nutrient

such as calcium carbonate for the growing of the shell. According to Ruppert et al.

(2004), most molluscs have muscular mouth with radula, 'tongues' bearing many rows

of chitinous teeth which are replaces from the rear as they wear out and this is

primarily designed to scrape bacteria and algae from the rocks. In most gastropods it

has radula which developed feeding organ that function as a grater, rasp, brush cutter,

gasper, harpoon or conveyor. The gastropod mouth consists of glands that secrete slimy

mucus and make the food become sticky and easy to drive towards the stomach. Some

mollusca are filter feeders on small particles of organic matter (Bhamrah, 1991).

According to Wan (2010), large gill where particles are trapped in mucus film then

passed a sticky cord along a ciliated groove' on the head and direct into the right side of

the mouth.

2.4 Molluscs as Pollution Indicators

Previous studies show that macrobenthic invertebrates are useful bio-indicators

providing a more accurate understanding of changing aquatic conditions than chemical

.'and microbiological data (George et aI. , 2009; Ravera, 1998, Ikomi et al., 2005).

Molluscs often used as the biological indicators of water pollution in certain places

(Shabdin & Rosniza, 2010). This is due to the mollusc characteristic which has the

potential to accumulate heavy metals in its body. According to Arthur (t 981), molluscs

community are affected three kinds of water pollution which are thermal, inorganic and

6

organic. Thermal pollution occurs when the river is used for industrial cooling. This

may heat the water enough to kill molluscs and also affect the reproduction cycle.

Inorganic pollution source is industrial. Industrial may contaminate the water to extent

of killing molluscs. Inorganic pollution maybe kills half the molluscs but some

molluscs can tolerance with the pollution. Organic pollution is caused by the sewage

and insecticides. Chemical analysis of the soft-parts of molluscs can reveal recent

pollution by insecticides. Macro-invertebrates are the common used in biological

method assessment of freshwater bodies receiving domestic and industrial wastewater

(Odiete, 1999). Their composition, abundance and distribution can be influenced by

water quality (Imevbore, 1967; Haslam, 1990; Odiete, 1999). They all stated that

variations in the distribution of macrobenthic organisms could be as a resuU of

differences in the local environmental conditions.

2.5 Molluscs Distribution in Borneo .

The study of gastropod and bivalve in Borneo had been done by Lim (1992) at Teluk

Mengkabong and Teluk Darvel. At Teluk Mengkabong terdapat 27 families and 80

species of gastropod with 17 families and 40 species of bivalve had been identified.

While at Teluk Darvel 28 families and 109 species Gastropod with 17 families and 37

species Bivalve was found. Beside that recent study by Wan (2010) at Asajaya

Mangrove Forest had success to identified 7 families and 14 species of gastropod with

4 families and 5 species of bivalve. There are 37' species gastropod and 26 species

bivalve had been recorded at the east coast of Malaysia (Shabdin & Rosniza, 2010).

However, only 27 species gastropod and 8 species bivalve are recorded found in Sabah

and Sarawak. From this record its can reflect that at east coast of Malaysia still rich

with molluscs species.

I

7

2.6 Diversity Indices

Species diversity is an appropriate term for ecologies who are interested in

understanding the mechanism and effects of certain ecological phenomena, such as

pollution and environmental disturbances (Bhatt, 2005). Species diversity usually

calculated using the Shannon Diversity Index (Poole, 1974). Besides that, species

richness and evenness also been measured whereas species richness is a total number

species in a given area and evenness which basically give the relative abundance of

distribution among the species (Magurran, 2004). Margalef Index (Margalef, 1985)

usually is used to find the species richness in certain area while Pielou's Evenness

Index (Poole, 1974) is used to determine the evenness between the species in the

community. Ecologists have invented a number of indices over years, each of which

has its own limitation (Magurran, 2004).

~.

8

3.0 MATERIALS AND METHODS

3.1 Study Area

19thFieldtrip was carried out from 15 th to October 2010 at Batang Kayan, Lundu

during low tide. The sampling was carried out in Batang Kayan River Estuary (Figure

1). From the observation of the water bodies during the fieldwork Batang Kayan, it can

be stated as turbid due to the high siltation which occur in the water. The silt sources

come from the erosion along the river bank. The effiuence source of turbid water

possibly from the domestic waste effiuents produce by the resident along the river.

Besides that there was oil plantation mill and erosion due to land clearing activities

near the Batang Kayan upper stream. The Batang Kayan Estuary vegetation is

dominated with few floras such as Sonneratia spp., Rhizophora spp. and Nypa sp. The

Nypa sp. was found at station 1 until station 3 while station 4 and 5 was dominated by

Sonneratia spp. and Rhizophora spp. Batang Kayan River is influenced by the tide

which occurs twice a day. This study. focused on two major classes of molluscs

(Gastropod and Bivalves) .

.'

9

Figure I: Location of sampling stations along the Batang Kayan River (Adapt from Google Earth)

10

3.2 Species Distribution Along The Estuary

Five stations had been chosen along the estuary (Figure I). Twenty five square meters

(5 m x 5 m) quadrate was located in each station randomly. All the species that were

found within the station were collected, labelled and brought back to the laboratory for

further analysis.

3.3 Species Zonation From The High Tide Level to Low Tide Level

The 5th station which located at the mouth of the estuary, line transect method had been

conducted. Two line transect were stretched from the high tide to low tide level. The

distance between each line transect was 100 m. The length of the line transect for first

line was 150 m while the second line was 300 m. There was 10 quadrates in the first

line transect with the distance between quadrate was 15 m. Meanwhile there were 6

quadrates in the second line transect with the distance between quadrate was 50 m.

Two replicates for each quadrate was carried out. The quadrate size was 0.25 m2 (0.5 m

x 0.5 m). All the molluscs found in the quadrate had been counted, identified and

recorded. Distance between each quadrate was fixed using the range finder (Model

ELITE 1500).

3.4 Vertical Zonation of Molluscs on The Tree Trunk

Six trees were sel.ected and the molluscs that had been found on the tree trunks were

collected. The height of the molluscs species on the tree trunks was measured using

measuring tape. The tree trunks had been divided into four zones (Figure 2). The

distance between each zone was around 30 cm.

11

-

Zone 4 ., 1 )

Zone 3 ~ 1

Zone2 lilt ~ 1

Zone 1

Figure 2: Vertical zonation of Molluscs on tree trunk ."

12

I

3.5 Pbysico-cbemical Parameters

Physico-chemical parameters such as dissolved oxygen (DO), temperature, pH,

turbidity and salinity were recorded. Physico-chemical parameters of the water were

measured at every station using Eutech measurement (Model PCD 650),

turbidity meter (Model TN-I 00) and refractometer (Model Atago S-I 0).

Eutech

3.6 Preservation

The collected sample of gastropod and bivalves species was preserved in 10 - 15 %

buffered fonnalin, labelled and brought back to the laboratory for further analysis.

3.7 Species Identification

The identification of the gastropod and bivalves species was based on the specimen

collection at Universiti Malaysia Sarawak Zoological Museum and other references

such as Arnold (1989), Arthur (1981), ~bdul (1991), Lim (1992), Leal (1996), Poutier

(1998) and Shabdin & Rosniza (2010).

3.8 Sediment Analysis

A total of five samples for each quadrates were taken at the line transect 1 and line

transect 2. Three samples were used for the chlorophyll a (ChI a) analysis and another ."

two samples were two samples were used for 'total organic matter (TOM) analysis

(Lorenzen, 1967)

13

3.9 Laboratory Works

3.9.1 Total Organic Matter

The total organic matter (TOM) analysis was done by heating the sediment

which collected from the line transect in the oven at 60°C to removed the water

contain in the sediment. The sediments were left in the oven for a day. After the

water completely removed, the sediments were weight as initial weight before

the sediments were put inside the furnace with the temperature 500 °C for 8 to

12 hours. Then the sediments were weighted as final weight to detennine the

weight loss.

The equations involved were as follows:

F = (E-D)/E

Where:

F = Total organic content

E = Crucible + Soil (60 °C, for 24 hours)

D = Crucible + Soil (400 °C, for 24 hours)

3.9.2 Cbloropbyll a

The chlorophyll a (Wasmund, 1984) was done by grinding the sediments inside

.' the mortar with 90 % of acetone. Then the sediments are transferred into

centrifuge tube about 12 ml of the sediment liquid. Then the solution were left

over for a night before centrifuge for 30 minutes at 4000 rpm then the reading of

chlorophyll at wavelength 665 nm were recorded. The recorded data was used in

calculation.

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