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COMMUNITY STRUCTURE OF BRACHYURAN

CRAB IN SETIU LAGOON, TERENGGANU

ZAKIRAH BT MOHAMAD TAUFEK

Thesis Submitted in Fulfillment of the requirement for the Degree of

Master of Science in the Institute of Oceanography and Environment

Universiti Malaysia Terengganu

July 2013

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DEDICATION

The work in this thesis is dedicated to my late father

Mohamad Taufek Bin Shahran

&

My beloved mother

Mazenah Bt. Simpol

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ABSTRACT

Abstract of thesis presented to the Senate of Universiti Malaysia Terenggganu in fulfillment of the requirements of degree of Master of Science

COMMUNITY STRUCTURE OF BRACHYURAN CRAB IN SETIU LAGOON, TERENGGANU

ZAKIRAH BT. MOHAMAD TAUFEK

July 2013

Main Supervisor : Associate Prof. Zainudin B. Bachok, Ph.D.

Co- Supervisor : Associate Prof. Mhd. Ikhwanuddin Abdullah, Ph.D.

Institute : Institute of Oceanography and Environment (INOS)

A study on the diversity and community structure of Brachyuran crab was

conducted in the Setiu lagoon, Terengganu. The sampling has been done once

in every two months for a year starting from July 2011 until May 2012. The study

aims to investigate the abundance and community structure of Brachyuran crab

in the Setiu lagoon. In addition, this study also investigated the relationship

between Brachyuran crab community and selected physico-chemical

parameters of waters such as salinity, pH and Dissolved oxygen) and sediment

grain size and total organic matter.

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The Setiu lagoon is stretched from Benting Lintang at the Northern part

and Penarik to the South. Totally, eight stations were placed. At the Northern

region (ST1 and ST2) the surrounding area covered mainly by Rhizophora sp.,

Nypa fruticans (Nipah palm) and Casuarina forest. In the middle region of the

lagoon (ST3, ST4, ST5) the area received seawater input from the nearest river

mouth. Meanwhile, at the southern region (ST6, ST7, ST8) the area received

freshwater input mainly from Setiu and Chalok river.The crab was sampled by

conducting 100 m2 quadrate. Within the quadrate, the crabs were collected in

five 1 m x 1 m subplot (five replicates) for 15-20 minutes time-based collection.

The physical parameters were measured in situ. The additional qualitative

method by using fishing device (crab trap and gill net) was employed as an

attempt to investigate subtidal species in order to increase the number of

Brachyuran species occurred in Setiu lagoon. However, results for subtidal was

not included for statistical analysis.

Totally, forty-four Brachyuran species were identified and grouped into 13

Families (Sesarmidae, Varunidae, Grapsidae, Ocypodidae, Macropthalmidae,

Dotillidae, Camptandriidae, Pilumnidae, Portunidae, Eriphiidae, Oziidae,

Dorippidae and Leucosiidae). Most of the species contributed by Sesarmidae

(18 species). Meanwhile, Portunidae accounted for 76% of total crab caught in

subtidal. The species obtained were mostly contributed by mangrove species.

Parasesarma plicatum recorded highest total number of individual crab caught

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(359 Individual) and followed by Scopimera sp. (199 Individual), Uca lactea

annulipes (156 Individual), Metaplax elegans (152 Individual), and

Cleistocoeloma merguiense (124 Individual).

The Brachyuran abundance was significantly varied between the stations

(p<0.05). The highest abundance was recorded at ST6 and ST2 (12 Ind.m-2 and

10 Ind.m-2 ) at the exposed area of intertidal flat with undergrowth of young

mangrove vegetations. ST1 (beach) was accounted for the lowest abundance

(2.12 Ind.m-2). Parasesarma plicatum (3-4 Ind.m-2), Scopimera sp. (2-3 Ind.m-2)

and Dotilla sp.(3-2 Ind.m-2) were occurred in high density at ST2, and ST6. In

turn, contribute to high density of Brachyuran crab in these stations. Though the

highest density was recorded in ST2, ST6, but ST5 (mix mangrove forest)

recorded the highest number of species, (S) (12 Ind.m-2), species richness (D)

(2.68±0.72), species evenness; (J’) (0.90±0.06) and species diversity (H’)

(2.17±0.32) as compared to othes stations. In contrast to ST5, ST7 (Nypa

mangrove forest) showed decreasing the number of species (7±3.32 Ind.m-2)

and diversity indices (D=2.29±1.16, J’= 0.80±0.11, H’=1.73±0.60,) and

occurrence of M.elegans in high abundance (3 Ind.m-2). The presence of M.

elegans and low number of species might influence by high Total Organic

Matter recorded in this stations. Similarly to ST7, the stations with less

vegetation covered (ST1 and ST8) also showed the reduction in number of

species (2-6 ind.m-2), and this lead to decreasing of H’ (0.51±0.26). Suggesting

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that heterogeneity of habitat and environmetal variables are responsible in

influencing the distribution of Brachyuran in this lagoon.

Seven species (P.plicatum, P.eumolpe, C.merguiense, Haberma sp., U.

lactea annulipes, U. vocans vocans, and M. aloutos) were widely distributed in

the Setiu lagoon (ST2, ST3, ST4, ST5, ST6, and ST8). ST1 (beach) and ST7

(Nypa forest) discriminate from the others stations in this lagoon by species-

specific occurred in both stations and totally absent at others station where ST1

discriminate by Ocypode ceratopthalmus and O.coridamanus while Labuanium

politum is presence only in ST7. Multi-Dimension Scaling (MDS) ordination

performed was clearly distinguished the stations into five distinct group; Group 1

(ST1), Group 2 (ST7), Group 3 (ST4), Group 4 (ST8), and Group 5 (ST2, ST6,

ST3 and ST5).

Pearson-correlation and linear regression analysis showed that salinity

and pH strongly correlated with D (pH, r= -0.83,p=0.01; salinity, r= -0.75,

p=0.03), and H’ (pH, r=-0.89, p=0.003; salinity, r=-0.82, p= 0.013). The

environmental variables might responsible for the Brachyuran occurrence in this

lagoon.The data obtain from this study might contribute to current information on

the brachyuan crab at the Setiu lagoon in turn provide importance baseline data

for future work and comparison with other habitat elsewhere in Malaysia.

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Abstrak thesis yang dikemukakan kepada pihak Senat Universiti Malaysia

Terengganu sebagai memenuhi keperluan ijazah Master Sains

KEPELBAGAIAN DAN STRUKTUR KOMUNITI KETAM BRACHYURA DI

KAWASAN LAGUN, TANAH BENCAH SETIU, TERENGGANU

ZAKIRAH BT. MOHAMAD TAUFEK

Julai 2013

Penyelia Utama : Prof Madya Zainudin B. Bachok, Ph.D.

Penyelia Bersama : Prof Madya Mhd. Ikhwanuddin B. Abdullah, Ph.D.

Institut : Institut Oseanografi dan Sekitaran (INOS)

Kajian mengenai kepelbagaian dan struktur komuniti ketam Brachyura

telah dijalankan dilagun Setiu,Terengganu. Persampelan telah dilakukan sekali

dalam setiap dua bulan bermula dari bulan Julai 2011 sehingga Mei 2012.

Kajian ini bertujuan untuk menyiasat kelimpahan dan struktur komuniti ketam

Brachyura di lagun Setiu. Di samping itu, kajian ini juga bertujuan untuk

mengenalpasti sama ada komuniti ketam Brachyura mempunyai perkaitan

dengan parameter terpilih fiziko-kimia air dan sedimen seperti kemasinan, pH,

oksigen terlarut, saiz pasir dan jumlah bahan organik.

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Kawasan lagun meliputi Benting Lintang di bahagian utara sehingga ke

Penarik di bahagian selatan. Terdapat lapan stesen secara keseluruhan. Di

bahagian utara (ST1 dan ST2), kawasan persekitaran dilitupi oleh Rhizophora

sp., Nypa fruticans (Nipah) dan hutan Casuarina, sementara ST3, ST4 dan ST5

di bahagian tengah lagun pula menerima kemasukan air laut daripada muara

sungai yang berdekatan. Di kawasan selatan iaitu ST6, ST7 dan ST8 ianya

menerima kemasukan air tawar dari Setiu dan Sungai Chalok. Persampelan

ketam telah dijalankan dengan menggunakan 100 m2 kuadrat. Dalam setiap

kuadrat, ketam telah disampel di dalam 1 m x 1 m subplot (5 replikasi).

Parameter fizikal telah diukur secara in situ. Kaedah kualitatif tambahan dengan

menggunakan alat memancing (perangkap ketam dan pukat tiga lapis) telah

digunakan sebagai satu usaha untuk mengenal pasti spesies subtidal.

Secara keseluruhannya, 44 spesies ketam Brachyura telah berjaya

diidentifikasi dan dikelaskan kepada 13 Famili (Sesarmidae, Varunidae,

Grapsidae, Ocypodidae, Macropthalmidae, Dotillidae. Camptandriidae,

Pilumnidae, Portunidae, Eriphiidae, Oziidae, Leucosiidae and Dorippiidae).

Kebanyakan spesies adalah daripada Famili Sesarmidae (18 spesies).

Sementara itu, Portunidae menyumbang sebanyak 76% daripada jumlah

keseluruhan ketam yang ditangkap di subtidal. Parasesarma plicatum

mencatatkan rekod bilangan individu tertinggi dalam 100 m2 kuadrat (359

Individu) diikuti oleh Scopimera sp. (199 Individu), Uca lactea annulipes (156

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Individu), Metaplax elegans (152 Individu) dan Cleistocoeloma merguiense (124

Individu).

Kelimpahan ketam Brachyura adalah lebih tinggi di kawasan terbuka

yang mempunyai tumbuh-tumbuhan bakau muda seperti di ST6 (12.43 Ind.m-2)

dan ST2 (10.33 Ind.m-2). Kepadatan terendah (2.12 Ind.m-2) direkodkan di ST1

(kawasan pantai). Terdapat perbezaan struktur komuniti yang signifikan pada

stesen-stesen ini (p<0.05). Kepadatan spesies Parasesarma plicatum (3-4

Ind.m-2), Scopimera sp. (3-4 Ind.m-2) dan Dotilla sp. (2-3 Ind.m-2) adalah tinggi di

stesen ST2 dan ST6. Walaupun kepadatan tertinggi direkodkan di ST2 dan

ST6, namun ST5 (hutan bakau) mencatatkan struktur komuniti yang tertinggi

berbanding stesen-stesen lain dari segi bilangan spesies (S)(12 Ind.m-2),

kekayaan spesies (D)(2.68±0,72), kesamarataan spesies (J')(0.90 ± 0.06) dan

kepelbagaian spesis (H')(2.17 ±0.32). Berbanding ST5, ST7 (hutan bakau

nipah) menunjukkan penurunan bilangan spesis (7±3,32Ind.m-2) dan indeks

kepelbagaian (D = 2,29±1,16, J '= 0.80± 0.11, H' = 1,73± 0.60) serta kehadiran

M. Elegans dalam kepadatan yang tinggi (3 Ind.m-2).

Kehadiran kepadatan yang tingggi untuk spesies M.elegans di ST7

mungkin antara faktor pengurangan bilangan spesies ketam Brachyura dan ini

mungkin dipengaruhi oleh jumlah bahan organik yang tinggi direkodkan di

stesen ini. Seperti ST7, stesen yang mempunyai kurang kepadatan tumbuh-

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tumbuhan (ST1 dan ST8) juga menunjukkan pengurangan bilangan spesies (2-

6 ind.m-2), dan seterusnya membawa kepada kepelbagaian spesies yang

rendah (0.51 ± 0.26). Stesen ini mempunyai peratusan jumlah bahan organik

yang tinggi dan sedimen bercirikan pasir halus, kelodak dan sedimen tanah liat.

.

Kajian menunjukkan bahawa ciri-ciri sedimen dan bahan organik

mungkin juga menyumbang kepada taburan Brachyura. Sebaliknya, ST1

(pantai) dan ST7 (hutan nipah) berbeza dari stesen-stesen lain di lagun ini

kerana kewujudan spesies yang spesifik dikedua-dua stesen ini dan tiada

terdapat di stesen lain di mana ST1 didiami oleh Ocypode ceratopthalmus dan

O. coridamanus manakala Labuanium politum hanya dijumpai di ST7 sahaja.

Ini menunjukkan bahawa kepelbagaian habitat dan pembolehubah persekitaran

bertanggungjawab dalam mempengaruhi taburan ketam Brachyura di lagun ini.

Tujuh spesies (P.plicatum, P.eumolpe, C.merguiense, Haberma sp., U.

lactea annulipes, U.vocans vocans dan M.aloutos) tertabur secara meluas di

lagun Setiu (ST2, ST3, ST4, ST5, ST6, and ST8). MDS ordinasi telah jelas

membezakan kesemua stesen kepada lima kumpulan yang berbeza; Kumpulan

1 (ST1), kumpulan 2 (ST7), kumpulan 3 (ST4), kumpulan 4 (ST8) dan kumpulan

5 (ST2, ST3, ST5, ST6).

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Pembolehubah persekitaran mungkin bertanggungjawab untuk taburan

dan kewujudan Brachyura di dalam lagun ini. Data yang diperolehi daripada

kajian ini dapat menyumbang kepada maklumat semasa mengenai ketam

Brachyura di lagun Setiu seterusnya menyediakan data asas yang penting

untuk kajian pada masa depan dan perbandingan dengan habitat di tempat

yang lain di Malaysia.

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ACKNOWLEDGEMENT

The most gracious and merciful of Allah to give the oppurtunity for me to

complete this thesis to finish my study within the time frame given. First of all, I

wish to express my greatest appreciation to my supervisor, Associate Prof. Dr.

Zainudin Bachok and Associate Prof Dr. Mhd Ikhwanudin Abdullah for their

patience and undying support. This thesis would not have been completed

without his expert advice and unfailing patience.

I would also like to express a special word of thanks to my family, and

Ahmad Syafiq. This thesis would not be accomplished without their endless

support, love and prayers. A special thanks to my labmates Nurul Zalizahana

Zakaria and Fatimah A’tirah which always on my side through the hard time,

tirelessly listen to my ideas and offered encouragement when it was most

needed. I am also most grateful for their faith in my study especially in the

sometimes difficult circumstances in which it was written.

I am very thankful for INOS staff for their friendliness and encouragement

during my hard times especially Mr. Joseph Bidai, Mr. Asmadi and Madam Siti

Tafzil Maryam, which assist me a lot in sampling from the beginning till the end.

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APPROVAL

I certify that an Examination Committee has met on 19th May 2013 to conduct the final examination of Zakirah Bt. Mohamad Taufek on her Master in Science thesis entitled “Community Structure of Brachyuran Crab in Setiu Lagoon, Terengganu” in accordance with the regulations approved by the Senate of Universiti Malaysia Terengganu. The Committee recommends that the candidate be awarded the relevant degree. The members of the Examination committee are as follows: Saifullah Ariffin B. Jaaman @ Sharman, Ph.D Associate Professor Institute of Oceanography and Environment (INOS) Universiti Malaysia Terengganu (Chaiperson)

Sulong B. Ibrahim Associate Professor South China Sea and Respirotory Centre Institute of Oceanography and Environment (INOS) (Internal Examiner)

Shabdin Mohd. Long, Ph.D. Professor Faculty of Resource Science & Technology Department of Aquatic Science Universiti Malaysia Sarawak (External Examiner)

______________________________

MOHD LOKMAN BIN HUSAIN, Ph.D Professor/Director of Institute of Oceanography and Environment Universiti Malaysia Terengganu

Date:

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APPROVAL

This thesis has been accepted by the Senate of University Malaysia Terengganu as fulfilment of the requirements for the degree of Master of Science.

______________________________ MOHD LOKMAN BIN HUSAIN, Ph.D Professor/Director of Institute of Oceanography and Environment Universiti Malaysia Terengganu

Date:

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DECLARATION

I hereby declare that the thesis is based on my original work except for

quotations and citations which have been duly acknowledge. I also declare that

it has been previously or concurrently submitted for any other degree at UMT or

other instituitions.

___________________________

ZAKIRAH BT MOHAMAD TAUFEK

Date:

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TABLE OF CONTENT

DEDICATION ii

ABSTRACT iii

ACKNOWLEDGEMENT xii

LIST OF TABLES xix

LIST OF FIGURES xxi

LIST OF PLATES xxiv

LIST OF ABBREVIATIONS xxviii

CHAPTER 1 1

INTRODUCTION 1

1.1 Background 1

1.2 Problem statement 5

1.3 Objective 7

CHAPTER II 8

LITERATURE REVIEW 8

2.1 Coastal wetlands 8

2.2 Coastal lagoon and associated ecosystem 10

2.2.1 Estuaries 10

2.2.2 Mangroves 11

2.3 Brachyuran crab 13

2.3.1 Scientific classification 13

2.3.2 Morphological terminology 15

2.4 Community ecology 19

2.4.1 Environmental factors 22

2.4.2 Distribution of Brachyuran crab 23

2.4.2.1 Mangrove ecosystem 23

2.4.4.2 Freshwater 25

2.5 Ecology and economic values 26

2.5.1 Brachyuran as ecosystem engineer 26

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2.5.2 Economic value 30

2.6 Brachyuran crab as bioindicator 31

2.7 Population estimation of Brachyuran crab 34

CHAPTER III 35

METHODOLOGY 35

3.1 Study Site 35

3.2 Field sampling 41

3.2.1 Brachyuran crab collection 41

3.2.2 in situ parameters 44

3.2.3 Sediment collection 44

3.3 Laboratory analyses 45

3.3.1 Brachyuran crab analyses 45

3.3.2 Sediment analysis 47

3.3.2.1 Grain size analysis 47

3.3.2.2 Organic matter analysis 49

3.4 Data analysis 50

3.4.1 Species composition and community structure 50

3.4.2 Correlation and ordination 51

CHAPTER IV 52

RESULTS 52

4.1 Environmental factors 52

4.1.1 in situ physico-chemical parameters 52

4.1.2 Sediment 57

4.1.2.1 Grain size distribution 57

4.1.2.2 Total Organic Matter 61

4.2 Brachyuran community structure 63

4.2.1 Species composition 63

4.2.2 Abundance of Brachyuran community 70

4.2.3 Brachyuran diversity 74

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4.2.4 Habitat preference 80

4.3 Relationship between Brachyuran crab with environmental parameters 82

4.3.1 Linear regression and correlation analysis 82

4.3.2. Ordination 86

4.4 Taxonomy and classification 90

4.4.1 Family Sesarmidae Dana, 1851 91

4.4.2 Family Varunidae H. Milne Edwars, 1853 104

4.4.3 Family Grapsidae Macleay, 1838 108

4.4.4 Family Ocypodidae Rafinesque, 1815 109

4.4.5 Family Dotillidae Stimpson, 1858 111

4.4.6 Family Macropthalmidae Dana, 1851 114

4.4.7 Family Camptandriidae Stimpson, 1815 117

4.4.8 Family Pilumnidae Samouelle,1819 123

4.4.9 Family Oziidae Dana, 1851 124

4.4.10 Family Menippidae Hilgendorf, 1879 125

4.4.11 Family Leucosiidae Samouell, 1819 126

4.4.12 Family Dorippidae Macleay, 1838 127

4.4.13 Family Portunidae Rafinesque, 1815 129

CHAPTER V 133

DISCUSSION 133

5.1 Abundance and species composition of Brachyuran crab 133

5.2 Brachyuran diversity 140

5.3 Brachyuran community structure in relation to environmental parameters 144

CHAPTER VI 150

CONCLUSION 150

REFERENCES 152

APPENDICES 165

BIODATA OF AUTHOR 188

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LIST OF TABLES

Table 2.1 Systematic classification of Brachyuran crab (Pechenik, 2010).

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Table 2.2 Report on Brachyuran crab use as bioindicator species for selected contaminants.

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Table 3.1 Location and sampling coordinates of stations in the Setiu lagoon

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Table 4.1 Mean ± standard deviation of in situ water parameters recorded in all stations of the Setiu lagoons from six month sampling periods starting from July 2011 to May 2012 (July 2011, September 2011, November 2011, January 2012, March 2012 and May 2012).

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Table 4.2 Mean of surface sediment grain size distribution and total organic matter in all stations of Setiu lagoons collected from six sampling period from July 2011 untill May 2012 (July 2011,September 2011, November 2011, January 2012, March 2012 and May 2012).

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Table 4.3 Statistical parameters of the sediment grain size in all stations in the Setiu lagoon in phi (ø) value.

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Table 4.4 A list of identified Brachyuran crab caught in intertidal station and total number of individual crab caught in 15-minutes time based collection.

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Table 4.5 A list of identified Brachyuran crab caught in subtidal stations and their relative abundance

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Table 4.6 An additional identified Brachyuran crab species (The by-catch crab caught not included in the stations).

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Table 4.7 Abundance (Ind.m-2) of Brachyuran crab species in each station. Data are recorded from six month sampling periods starting July 2011 untill May 2012 (July 2011, September 2011, November 2011, January 2012, March 2012 and May 2012) (n=6).

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Table 4.8 Univariate measures of community structure parameters of Brachyuran crab caught from 6 sampling periods starting July

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2011 untill May 2012 ( July 2011, September 2011, November 2011, January 2012, March 2012 and May 2012). The data was mean and standard deviation.

Table 4.9 Habitat preference of Brachyuran crab in intertidal and subtidal of Setiu lagoons.

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Table 4.10 Pearson-Linear Correlation r between each environmental variables and community indices; Abundance (A), Richness (D), Evenness (J’), and Shannon-Wiener Diversity (H’).

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Table 4.11 Summary of Redundancy analysis (RDA) results of Brachyuran community in the lagoon area of Setiu Wetland.

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Table 5.1 Report of occurrence the intertidal Brachyuran crab in Malaysia and adjacent region.

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LIST OF FIGURES

Figure 2.1 General shape (dorsal view) of Uca sp. from Family Ocypodidae (the terminology use adapted by Crane, 1975)

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Figure 2.1 Descriptive terms of: A) the dorsal view of the carapace; B) Frontal view (illustration by Lovett, 1981)

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Figure 2.2 Descriptive terms of: A) Frontal view of carapace; B) Eyes, antennae and antennules (illustration by Lovett, 1981).

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Figure 2.4 The ecological process involvement by Brachyuran through feeding and burrowing behaviour (adapted by Kristensen, 2008).

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Figure 2.5 Schematic drawing showing a crab burrow; A) The typical shape and dimension of fiddler crab burrows; B) Sesarmid crab burrows (source Kristensen, 2008).

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Figure 4.1 Rainfall recorded from July 2011, September 2011, November 2011, January 2012, March 2012 and May 2012) (n=3).

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Figure 4.2 Mean ± Standard deviation for seasonal variations of In-situ water salinity in July 2011 to May 2012 with two month interval (n=3); (July 2011, September 2011, November 2011, January 2012, March 2012 and May 2012).

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Figure 4.3 Mean ± Standard deviation for seasonal variations of in situ pH value in July 2011 to May 2012 with two month interval (n=3); (July 2011, September 2011, November 2011, January 2012, March 2012 and May 2012).

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Figure 4.4 Mean ± Standard deviation for seasonal variations of in situ Dissolved oxygen in July 2011 to May 2012 with two month interval (n=3); (July 2011, September 2011, November 2011, January 2012, March 2012 and May 2012).

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Figure 4.5 The sediment mean size value in all stations of Setiu lagoon. The surface sediment collected from six sampling period from July 2011 untill May 2012 (July 2011, September 2011, November 2011, January 2012, March 2012 and May 2012).

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Figure 4.6 Principal component analysis (PCA) ordination derived from the mean percentage of particle fractions in each station.

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G=Granule (4mm), VCS=Very coarse sand (2mm); CS= Coarse sand (1mm); MS=Medium Sand (250µm); FS= Fine sand (150 µm); VFS= very fine sand (63µm); SC= Silt and clay (<63µm)

Figure 4.7 Percentage of surface sediment Total Organic Matter for 6 month sampling period starting July 2011 to May 2012 (July 2011, September 2011, November 2011, January 2012, March 2012 and May 2012).in the Setiu lagoon. The data were mean with standard deviation (n=6).

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Figure 4.8 The pie chart showed Brachyuran number of individual in the main Family in percentage of total number of individuals, A) Intertidal; B) Subtidal of Setiu lagoon. Data were mean from six sampling periods (n=6) (July 2011, September 2011, November 2011, January 2012, March 2012 and May 2012).

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Figure 4.9 Percentage distribution of Brachyuran based on major Family in each station; intertidal (ST1-ST8) and subtidal (SF1-SF3). Data were mean from six sampling periods (n=6) (July 2011, September 2011, November 2011, January 2012, March 2012 and May 2012).

65

Figure 4.10 Mean abundance of Brachyuran crab in intertidal stations. Data was collected from six month sampling periods starting July 2011 untill May 2012 (July 2011, September 2011, November 2011, January 2012, March 2012 and May 2012) (n=6).

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Figure 4.11 Temporal variation of Brachyuran abundance in the Setiu lagoon from 6 sampling period starting July 2012 until May 2012 with two month interval. Data are recorded starting July 2011 untill May 2012 (July 2011, September 2011, November 2011, January 2012, March 2012 and May 2012) (n=6).

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Figure 4.12 Temporal variation of diversity indices of Brachyuran in the Setiu Lagoon from six sampling periods starting July until May 2012.

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Figure 4.13 Dendogram produced by cluster analysis showing the percentage of similarity between the intertidal stations by using mean abundance of Brachyuran species collected from one year sampling periods with two month interval (July 2011, September 2011, November 2011, January 2012, March 2012, and May 2012).

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Figure 4.14 MDS ordination constructed from the mean abundance of Brachyuran species collected from one year sampling periods

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with two month interval (July 2011, September 2011, November 2011, January 2012, March 2012, and May 2012).

Figure 4.15 The scattered plot of linear regression between; (A) species richness and; (B) Species diversity in relation to increasing of salinity.

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Figure 4.16 The scattered plot of linear regression between species richness (D); and species diversity (H’) in relation to increasing of salinity.

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Figure 4.17 Triplot diagram of RDA showing the relationship between Brachyuran communities with the environmental variables in the Setiu lagoon.

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LIST OF PLATES

Plate 4.1 A, B) Overall view of Perisesarma indiarum (UMTCrust00138) and Perisesarma eumolpe (UMTCrust00103); Ventral view of C) P.indiarum; D) P.eumolpe E) P. indiarum foraging near the water edge during low tide (CL=12-29mm)

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Plate 4.2 A) Overall view of Parasesarma plicatum (Latreille, 1806) (UMTCrust00116) (CL= 14.31); B). P.plicatum were abundance in open area covered with grass and undergrowth of mangrove vegetation; C) Ventral view with the aspect of chela; D) Right male chela (drawing illustration adapted from Naderloo and Schubart, 2010).

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Plate 4.3 Clistocoeloma merguiense (De Man, 1888) (CL=27.5mm) (UMTCrust00146). A) Overall view; B) Carapace, dorsal view C) Frontal view; D) Left cheliped; E) Male abdomen (the illustration was adapted from Hsueh and Huang, 1996).

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Plate 4.4 A, C) Overall view of Nanosesarma sp.1 (UMTCrust00125) (CL=1.4mm) and Nanosesarma sp. 2 (UMTCrust00124) (CL=1.3mm); B) Ventral view of Nanosesarma sp.1; D) Ventral view Nanosesarma sp.2; E) Cavities made by wood boring isopoda where these species collected.

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Plate 4.5 Labuanium politum (De Man, 1888) (CL=30.0mm) (UMTcrust00146). A) Overall view; B) Ventral view; C) Nypa fruticans mangrove forest.

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Plate 4.6 Episesarma singaporense (Tweedie, 1936) (CL=32.0mm) (UMTcrust00146). A, overall view; B) Ventral view; C,D) E.singaporense feed on fallen leaf of Rhizophora sp.

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Plate 4.7 Haberma nanum (UMTCrust00107) (CL=1.5mm). A) Overall view; B) Dorsal view; C) Ventral view of female abdomen; D) H.nanum was found over a burrow of mud lobster mounds.

101

Plate 4.8 Neosermatium sp. (UMTcrust00108)(CL=11.5 mm); A) overall view; B) Ventral view with the aspect of male abdomen and chela; C) ST4, the specimen collected; D) Ventral view with the aspect of berried female abdomen and chela; E) Life colouration in natural habitat.

102

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Plate 4.9 Plate 4.1: Varuna litterata, (UMTCrust00115) (CL=29 mm); A) dorsal view; B) ventral view; C) Ventral view with aspect of outer faces of chelae; D) Intertidal flat of ST3.

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Plaet 4.10 Hemigrapsus sp. (UMTCrust00133) (CL=16.3 mm); A) Dorsal view of carapace; B) Ventral view; C) Frontal view.

105

Plate 4.11 A) Overall view of Metaplax elegans (UMTCrust00122) (CL=17.4mm); B) Ventral view with the emphasize of chela; C) M.elegans foraging during low tide.

106

Plate 4.12 A) Overall view Metopograpsus frontalis (UMTCrust 00105)(CL=30.2mm); B) Metopograpsus latifron (White)(UMTCrust 00151)(CL=30 mm); Ventral view with the emphasize of cheliped C) Metopograpsus frontalis; D) Metopograpsus latifrons; E) Half of carapace in dorsal view Of M.frontalis F) Half of carapace in dorsal view Of M.latifron (drawing illustration adapted from Banerjee, 1960).

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Plate 4.13 Overall view of, A) Ocypode ceratopthalmus (Pallas, 1772) (UMTCrust00150) (CL=34.5); B) Ocypode cordimanus (Latreille, 1818) (UMTCrust00147) (CL=21mm).

109

Plate 4.14 Different of male claw of A) U. vocans (UMTCrust00101) (CL=11.2 mm) and; B) U. annulipes (UMTCrust00148) (CL=9.8mm); C) U. parplexa H.Milne Edwars, 1852 (UMTCrust00102) (CL=10.1); D) A group of Uca spp. foraged in the exposed sandy substratum along the banks during low tide.

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Plate 4.15 Dotilla sp. (Stimpson, 1858) (UMTCrust 00111)(CL=9.6mm); A) Overall view; coloured altered by preservation; B)Ventral view; C) Red circle indicate the open intertidal sand-flat where the Dotilla sp. collected.

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Plate 4.16 Overall view of Scopimera sp. (UMTCrust00109); B) Ventral view with the aspect of chelae and male abdomen; C) Red circle show the burrows of Scopimera sp.

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Plate 4.17 Macropthalmus sp.1 (UMTCrust00104) (CL= 35 mm). A) Overall view; B) Female ventral view; C) Male ventral view ; D) crabs were collected in the muddy substratum.

114

Plate 4.18 Macropthalmus sp.2 (UMTCrust00137) (CL= 36.7 mm). A) Overall view; B) Male ventral view.

115

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Plate 4.19 Ilyograpsus nodulosus (UMTCrust00136) (CL= 4.7 mm); A-B) Dorsal View; C) Ventral view with the aspect of male abdomen and chelae; D) Frontal view.

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Plate 4.20 Plate 4.2: Paracleistostoma eriophorum (UMTCrust00113) (CL= 6.32 mm) A-C) Dorsal View; D) Ventral view with the aspect of male abdomen and chelae.

117

Plate 4.21 Plate 4.3: Paracleistostoma sp.1 (UMTCrust00112) (CL=8.25 mm). A) Dorsal View; B) Ventral view.

117

Plate 4.22 Plate 4.22: Moguai aloutos (UMTCrust00119) (CL=0.97 mm) A) Overall view; B) Ventral view of female; C) Ventral view of male.

119

Plate 4.23 Plate 4.23: Baruna socialis (UMTCrust00135) (CL=3.2 mm); A) Overall view; B) Dorsal view of carapace region; C) Female abdomen; D) Male abdomen.

120

Plate 4.24 Baruna mangromunphia Stebbing, 1904 A) Dorsal view; B) Ventral view of berried female; C-H C) Dorsal view of male carapace D) Dorsal view of female carapace E) Inner surface view of right fourth ambulatory leg; F) Inner surface view of left third ambulatory leg Female abdomen; G) Female abdomen; H) Male abdomen (illustration adapted from Harminto & Ng, 1991).

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Plate4.25 Xenopthalmus sp. (UMTCrust00149) (CL=5.1 mm) A) Overall view; B) Frontal view.

122

Plate 4.26 Heteropanope glabra (UMT00134) (CL=8.97mm); A) Overall view; B) Dorsal view of carapace region; C) Ventral view with the aspect of chela and abdomen.

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Plate 4.27 Overall view of Epixanthus dentatus White, 1848 (UMTCrust00141) (CL= 43.7-74.5 mm).

124

Plate 4.28 A) Overall view of Myomenippe hardwickii; B) Vental view with the aspect of chela (UMTCrust00140) (CL=42.3-94.6 mm).

125

Plate 4.29 Praosia punctata (UMTCrust00118) (CL 1.4mm) A) Overall view; B) Ventral view showing male abdomen; C) Ventral view showing female abdomen.

126

Plate 4.30 A leaf porter crab (Neodorippe callida) (UMTCrust0017) 127

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(CL=13.6mm) A) Overall view; B) Ventral view.

Plate 4.31 Thalamita crenata (UMTCrust00110) (CL=72.53-97.8mm). A) Overall view; B) Ventral view aspect of chela.

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Plate 4.32 Portunus pelagicus (UMTCrust00139) (CL=129.21 mm). A) Overall view; B) Ventral view aspect of male abdomen.

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Plate 4.33 A-C) Overall view of Scylla spp.; A) S.paramamosain Estampador, 1949 (UMT00142) (CL=58.24-124.40mm); B) S.tranquebarica Fabricius, 1798 (UMT00143)(CL=47.31-111.33mm); C) S.olivacia Herbst, 1796 (UMT00144)(CL=50.15-109.03 mm); D-F) Frontal view with the aspect of cheliped; D) S.paramamosain; E) S.tranquebarica; F) S.olivacia.

132

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LIST OF ABBREVIATIONS

mm - millimetre

cm - centimetre m - meter g - gram µm Micrometer mg/L - Milligram per litter No.Ind.m-2 - Number of individual per square meter °C - Degree celcius PSU - Practical Salinity Unit DO - Dissolved oxygen TOM - Total organic matter SD - Standard deviation ANOVA - Analysis of Variance PCA - Principal Component Analysis CCA - Cananonical Correspondence Analysis RDA - Redundant Analysis sp. - Species UMTCrust - INOS Museum Collection number for crustacean

sample ST - Stations in intertidal SF - Stations in subtidal Jul-11 - July 2011 Sep-11 - September 2011 Nov-11 - November 2011 Jan-12 - January 2012 Mar-12 - March 2012 May-12 - May 2012 S - Number of species D - Species richness index J’ - Species evenness index H’ - Species diversity index Ø - phi

1

CHAPTER 1

INTRODUCTION

1.1 Background

Wetland is a productive ecosystem that contributes to aquatic and

terrestrial biodiversity (Woodroffe and Davies, 2009) and plays a great role in

sustaining biological diversity and provide significant ecological, social and

economics functions (Mann, 2000; Woodroffe and Davies, 2009).

Terengganu is situated at the East-coast of Peninsular Malaysia. Setiu

wetland is located along the coastal area facing South China Sea in the

northern state of Terengganu with total water surface area about 880 ha (Ong et

al., 2009). The wetlands comprise unique inter-connected ecosystem including

Melaluecae forest (known as Gelam forest), mangrove, estuaries, beach, river,

intertidal mud-sandy flats and lagoons (Ibrahim and Abdullah, 2003).These

2

ranges of habitats provide a variety of flora communities which in turn support

suitable habitat to animal communities. Natural resources derived from this

wetland create socio-economic opportunities to local communities, including

artisanal and commercial fisheries, small scale to extensive cage and earthern

pond aquaculture, charcoal production and small-scale manufacturing of

traditional food (Yaacob et al., 2006).

The Setiu lagoon is the largest coastal lagoon that can be found in

Terengganu coast stretching with approximately 20 km from Penarik at the north

to Benting Lintang at the south. Previously, there were several research that has

been done in depth in Setiu lagoon, including targeted seagrass distribution

(Gan, 2011), specific faunal groups such as mud crab (Ikhwanuddin et al., 2010,

Zaidi et al., 2011), river terrapin, bird and bat (Tamblyn et al., 2006) and

environmental health assessment such as heavy metal (Ong et al., 2009) and

sedimentology (Husain et al., 1995; Kasawani et al., 2010; Yaacob and Zaini,

2010).

Brachyuran crabs are one of the most important decapod members

inhabiting wetland ecosystem. Wetland ecosystem offers a vast array of habitat

for Brachyuran crab in turn contribute to biological diversity for this ecosystem.

Within the wetland, Brachyuran crab covers wide range of distribution ranging

3

from terrestrial, semi terrestrial and aquatic environment. These include

mangrove forest, intertidal flats, river, swamp forest, estuaries, lagoon and

beach. In Malaysia, previously there were several studies has been done to

investigate the distribution of brachuyuran species in targeted ecosystem

including the mangrove (Tan and Ng 1994; Sasekumar and Chong, 1998;

Ashton et al., 2003a, 2003b), freshwater ecosystem (Ng, 1988; Ng, 1995,

Cumberlidge et al., 2009; Yeo et al., 2008), island (Yeo and Ng, 1999), and

even in the cave (Mcfarlane et al., 2011). Their distribution also influence by

several environmental factors such as water salinity, water temperature and

tidal inundation, soil pH, salinity, organic content, sediment characteristic (Smith

et al., 1991; Koch et al., 2005) and how they adapted and tolerate with these

environmental factors. They also contribute a significant role in ecological

functions (Smith et al., 1991; Nourdhaus et al., 2006; Kristensen, 2008) and

form important link in food web between detritus at the base of trophic level and

higher consumers (Koch et al., 2005).

The mangroves ecosystem contributes to high proportion number of

Brachyuran species which dominated by two families, Ocypodidae and

Grapsidae, in terms of abundance and biomass in the Indo West Pacific

mangrove forests (Lee 1989; Lee 1998; Ashton et al., 2003a; Cannicci et al.,

2008). The distribution of Brachyuran crab in intertidal mangrove ecosystems

has been explained by various authors (Smith et al., 1991; Sasekumar and

4

Chong, 1998; Ashton et al., 2003a, 2003b; Nagelkerken et al., 2008; Ng et al.,

2008). The Brachyuran crab makes up about 80% of the macrofauna biomass

and can reach densities of 80-90 per m2 (Smith et al., 1991; Nordhaus et al.,

2006; Bandekar et al., 2011) also result in high percentage (76%) of the total

biomass of mangrove fauna (Smith et al., 1991). Sanchez and Raz-Ghuzman

(1997) has reported that some Brachyuran crab species have been recognized

as regulators of the estuaries structure and importance in terms of their

abundance and support high species richness in this ecosystem.

5

1.2 Problem statement

To date, there is little study on Brachyuran crab in the Setiu lagoon. The

number of Brachyuran crab species in this lagoon is still undiscovered and yet

little study was conducted. As consequences, this area constitutes a gap in the

known distribution of Brachyuran crab. Previous studies have been done in this

lagoon focusing on targeted species Scylla spp. (Ikhwanuddin et al., 2010)

which is commercially important species and has high demand from local

consumers and for aquaculture purpose. Hence, there is a need to explore

these valuable crab communities as a whole and should not be neglected as

they are important in foodweb and economic development in this area.

A fundamental property of understanding any ecosystem habitat is the

number of species it contains (Henderson, 2003; Likens, 2005). Therefore, it is

a need to explore in-depth the occurrence of Brachyuran crab species in this

lagoon. Nowadays, anthropogenic disturbance to natural ecosystems often

result in degradation of ecosystem and may lead to diversity loss. However, the

consequences on the ecosystem are often unrecorded due to lack of baseline

studies in interest ecosystem.

6

They are crucial for the maintenances of biodiversity in this lagoon since

coastal areas across the world are under increasing population and

development pressures. Alteration on this ecosystem such as land clearing will

directly cause habitat destruction for Brachyuran and others flora and fauna

especially for those species that live in a semi-terrestrial life, breathing air, living

in burrows and dividing their time between water and land, appear most at risk,

possibly because their habitats are most easily disturbed by human activities.

Unfortunately, it appears that there is still less of detailed published

information on the occurrence of Brachyuran crab in the Setiu lagoon.

Moreover, there seems to be limited published data on these faunal

documented in the Terengganu. Several reports are available from Malaysia

was recorded by Leh and Sasekumar, (1985); Tan and Ng, (1994); and Ashton

et al., (2003a, 2003b). Unlike other countries where continues research update

of recent new Brachyuran species were discovered from time to time.

Hence, finding of this study especially the current list of Brachyuran

species is expected to be useful as baseline information for future systematic

and ecological studies in this area. Wihout detail documentation and systematic

studies on the interest species in particular ecosystem or habitat, an animal may

no longer exist to humans. Without a name, we have no framework with which

to study the organism, and no way to understand its unique ecological role (Ng

et al., 2008).

7

1.3 Objective

This study specifically focuses on the following objectives:

1. To identify the Brachyuran crabs in the lagoon area of Setiu Wetland up

to their lowest taxonomic level.

2. To investigate the community structure of Brachyuran crab within the

Setiu lagoon ecosystem.

3. To determine the relation of Brachyuran crab community structure with

selected environmental parameters of Setiu lagoon.

8

CHAPTER II

LITERATURE REVIEW

2.1 Coastal wetlands

Nowadays, protection and conservation of wetland ecosystem has

received high concern by many organizations. Comparing to the other

ecosystem, wetland was the first ecosystem to receive international attention

through the convention of Wetland International, opened for signature at

Ramsar, Iran, in February, 1971 (Woodroffe and Davies, 2009). According to

definition by Ramsar Convention, wetland is “the areas of marsh, fen, peat land,

whether natural, artificial, permanent or temporal, with water that is static or

flowing, fresh, brackish or salt, including areas of marine water the depth of

which at low tide does not exceed six meters. These areas may incorporate

riparian and coastal zones adjacent to the wetlands, and islands or bodies of

marine water deeper than six metres at low tide lying within the wetlands”. In

Malaysia, there are 105 wetland areas. However, over the hundred only six

wetlands were gazetted as a Ramsar site and Setiu wetland was listed as

potential Ramsar site in Malaysia (Wetland International Malaysia, 2007).

9

Vegetation composition and water fluctuations make a range of wetland

ecosystem available at different times of the year for aquatic and terrestrial

animals. In the intertidal ecosystem the distribution of Brachyuran species are

related to their adaptations to abiotic conditions, vegetation density and

composition, their social and feeding behaviour (Dahdouh-Guebas et al., 2002;

Ashton et al., 2003b, Joscha et al., 2012).

Within a wetland, the environmental characteristic is the main factors to

produce a great range of wetland types (Mann, 2000; Woodroffe and Davies,

2009). Kjerfve, (1994) define the coastal lagoon ecosystem as “shallow coastal

water body separated from the ocean by a barrier, connected at least

intermittently to the ocean by one or more restricted inlets, and usually oriented

shore-parallel” while Vadineanu, (2005) define coastal lagoon ecosystem as

transition area of land and sea or more related to wetland, the interface areas

between land and water.

10

2.2 Coastal lagoon and associated ecosystem

2.2.1 Estuaries

Definition of an estuary is adapted from Kjerfve, (1994). “An estuary is the

semi-enclosed region, as freshwater and saltwater mixing. Estuaries water

varies from freshwater to salty, with much of it an intermediate mixture that is

described as brackish. Estuary is dynamic water systems where there is

continuously changing of physical, chemical and biological activity”. Estuaries

may take the form of semi enclosed bays, or shallow lagoons often associated

with sandbars at their seaward edge (Walker and Wood, 2005).

The mixing of this water affects the overall salinity of the estuary and

which organisms can live to this environment (Walker and Wood, 2005).

According to Mann, (2000) the special feature of estuaries is related to two main

physical processes. First feature is water density characteristic. Freshwater is

lighter than saltwater and often gives rise to a two-layered system. The second

special feature is that rivers commonly bring a load of suspended sediment to

the estuary. Settlement of the sediment in the estuary produces fertile ground

for the growth of salt-tolerant flowering plants such as seagrass and mangroves

which give estuaries a special biological characteristic (Walker and Wood,

2005).

11

Mangroves, seagrass beds, salt marshes, mudflats considered as

subsystem of an estuary (Mann, 2000). Estuaries are the only kind of

environment capable to support a great diversity of freshwater and saltwater

residents and passerby. Some of these species use the estuaries as nurseries

ground (Walker and Wood, 2005). Within the tropics, estuarine habitats are well

developed, with mangroves as the characteristic large plant (Mann, 2000).

2.2.2 Mangroves

In the coastal lagoon ecosystem, mangroves forests usually occur at river

mouths and the intertidal zone at the interface between land and sea. The

vegetation must have the ability to withstand inundation (Mohd-Lokman, 2004).

Mangroves defined as trees and shrubs or palms that reach the height

exceeding 0.5 m (Woodroffe and Davies, 2009) throughout the tropics and

subtropics region with latitude between 25°N and 25°S (Mann, 2000).

The root system is another unique feature of mangrove forest. Generally,

mangrove forest divided into several zone according to tree assemblages. The

zones is determined by the interaction by several environmental factors such as

tidal flooding, soil types, salinity of ground floor, frequency of inundation by

12

seawater, water flow and soil humidity and geographical condition in mangroves

(Pernetta, 1993; Dahdouh-Guebas et al., 2002; Koch et al., 2005).

The Indo-west pacific possesses the most abundant mangrove forest in

terms of species richness and species diversity (Siddiqi, 2001). At least 105

recorded mangrove vegetation species were occurred in the Malaysia and

Terengganu in particular comprise 29 exclusive mangrove vegetation species

(Appendix). Most of the mangroves in the Terengganu were classified as

estuarine type (Husain and Ibrahim, 2001). The Setiu Wetland was the second

largest area of mangroves stand in Terengganu. The mangroves were

flourishing inside the lagoon-estuary ecosystem which facing the South China

Sea. The mangroves are characterised as fringing type and primarily dominated

by Rhizhopora spp.and Nypa fruticans (Husain and Ibrahim, 2001).

13

2.3 Brachyuran crab

2.3.1 Scientific classification

Table 2.1: Systematic classification of Brachyuran crab (Pechenik, 2010).

Phylum Arthropoda

Subphylum Mandibulata

Class Crustacea

Subclass Malacostraca

Order Decapoda

Infraorder Brachyura

Phylum Arthropoda, one of the largest arthropod groups in the animal

kingdom with over 42,000 extant species. Globally, there are currently 6,700

species of Brachyuran crab were recorded (Yeo et al., 2008). The term

crustacea refers to the hard chitinous exoskeleton. Brachyuran crabs (true crab)

belong to infraorder Brachyuran. Normally, they are referring to the members of

shrimp, lobster and crayfish and hermit crabs. They are also sometimes

confused with hermit and porcelain crab from infraorder anomura. A full

classification is represented in Table 2.1 according to Pechenik (2010).

14

Brachyuran crab is also classified regarding to their feeding types. For

example, species of the family Ocypodidae are group as sediment feeders and

the Grapsid species are generally omnivorous (Bouillon et al., 2002).

Nowadays, advance research in systematic studies was introduced based on

molecular technique. The molecular biologist suggest that this technique are

considered powerful tools to be used in order to have better understanding of

Brachyuran phylogeny and systematic classification as compared to

conventional method by using morphological data to solve systematic problems

(Ng et al., 2008). However, down site of this matter, the morphologists must

take into account that molecular data as an additional information to be

assessed. Indeed, the conventional method of morphological data should not be

ignored (Ng et al., 2008). Therefore, integrated approaches of systematic

studies and available knowledge such as through adult and larval morphology

(Guerao, et al., 2004), molecular (Silva, et al., 2010), ecology (Ng et al., 2010),

and physiology (Ng et al., 2008) are required in order for better understanding

of Brachyuran taxonomy and classification.

15

2.3.2 Morphological terminology

Basically, Brachyuran crab body consists of broad carapace consisting of

the head (cephalic) and strongly reduced abdomen that is tightly tucked

underneath the body (Figure 2.1). The external morphology of crabs has

evolved into a body with modified segments and appendages (Figure 2.2 and

Figure 2.3) that are specialized for distinct purposes such as feeding, defence,

swimming, reproduction and respiration. These modifications enable them to

adapt and exist within their respective habitats (Warner, 1977).

Figure 2.3: General shape (dorsal view) of Uca sp. from Family Ocypodidae; 1,2,3, and 4 refer to walking leg (the terminology use adapted from Crane, 1975)

1

2

3

4