MORPHOMETRIC VARIATIONS AND POPULATION SIZE OF HORSESHOE CRAB (Tachypleus gigas) IN TELUK SENANGIN, PERAK, MALAYSIA
By CHEE HON YUNG
A Final Year Project report submitted in partial fulfillment of the requirement of the award of the degree of Bachelor of Applied Science (Conservation and Management of Biodiversity)
SCHOOL OF MARINE AND ENVIRONMENTAL SCIENCES UNIVERSITI MALAYSIA TERENGGANU 2015
PROGRAM SARJANA MUDA SAINS GUNAAN (PEMULIHARAAN DAN PENGURUSAN BIODIVERSITI) PUSAT PENGAJIAN SAINS MARIN DAN SEKITARAN UNIVERSITI MALAYSIA TERENGGANU
PENGAKUAN DAN PENGESAHAN LAPORAN PROJEK PENYELIDIKAN TAHUN AKHIR FINAL YEAR PROJECT REPORT VERIFICATION
Adalah ini diakui dan disahkan bahawa laporan penyelidikan bertajuk: Morphometric Variations and Population Size of Horseshoe Crab (Tachypleus gigas) in Teluk Senangin, Perak, Malaysia oleh Chee Hon Yung, UK 28922 telah diperiksa dan semua pembetulan yang disarankan telah dilakukan. Laporan ini dikemukakan sebagai memenuhi sebahagian daripada keperluan memperolehi Ijazah Sarjana Muda Sains Gunaan (Pemuliharaan dan Pengurusan Biodiversiti), Pusat Pengajian Sains Marin dan Sekitaran, Universiti Malaysia Terengganu.
Disahkan oleh: / Verified by: ……………………………………… Penyelia Utama / Main Supervisor Nama / Name: Cop Rasmi / Official Stamp: Tarikh / Date: ……………………………………… Pengerusi Program / Chairman of the Programme Nama / Name: Cop Rasmi / Official Stamp: Tarikh / Date:
…………………………………….. Penyelia Bersama / Co-supervisor Nama / Name: Cop Rasmi / Official Stamp: Tarikh / Date:
DECLARATION
I hereby declare that this Final Year Project report entitled Morphometric Variations and Population Size of Horseshoe Crab (Tachypleus gigas) in Teluk Senangin, Perak, Malaysia is the results of my own research except as cited in the references.
Signature Name Matric‟s No. Date
: _______________ : Chee Hon Yung : UK 28922 : 17th May 2015
iii
ACKNOWLEDGEMENTS
I would like to thank all those people who made this thesis possible and enjoyable experience for me. First of all I wish to express my sincere gratitude to my supervisor, Dr. Faridah binti Mohammad and co-supervisor, Dr. Amirrudin bin Ahmad for their valuable advises, patience and guidance throughout the study. I would also like to gratefully acknowledge my seniors for helping me during the sampling especially Azwarfarid Manca, Muhd. Fawwaz Afham Mohd. Sofa and Nur Fairuz binti Fozi. My special thanks also to Horseshoe Crab Research Group (HSCRG) UMT for supporting this project. I also appreciate and thanks to fishermen and villagers in Teluk Senangin for providing valuable information during the sampling process. I would like to take this opportunity to thank to all my friends for their encouragement and support during my study. Finally, I would like also to express my deepest gratitude for a constant support, emotional understanding and love that I received from my family. Thank you.
iv
MORPHOMETRIC VARIATIONS AND POPULATION SIZE OF HORSESHOE CRAB (Tachypleus gigas) IN TELUK SENANGIN, PERAK, MALAYSIA
ABSTRACT
There are four species of horseshoe crabs in the world and three species can be found in Malaysia. The coastal horseshoe crab, Tachypleus gigas population was established in both Peninsular Malaysia and Borneo. However, the information for the population size of T. gigas in the west coast of Peninsular Malaysia is limited. The objectives of this study were to estimate the population size and to measure the morphometric parameters of the horseshoe crab (T. gigas) in Teluk Senangin, Perak, Malaysia. The study was conducted in October 2014 and January 2015 using capture-mark-recapture (CMR) method. The samples were marked with button tag for each capture and released back to their natural habitat before randomly recaptured with one day interval after release. The population size of T. gigas in Teluk Senangin was ranged between 1743 to 10 385 individuals by using Chapman‟s modified Peterson formula (1982). The average total length of the male horseshoe crab was 34.79±1.83 cm and female was 38.50±7.34 cm. The average weight of the male horseshoe crab was 268.75±34.48 g and 573.0±204.62 g for female. The relationship between various body parts of T.gigas captured in Teluk Senangin reveal linear relationship in most cases. All relationships showed negative allometry in male and female except for the Total Length – Carapace Length relationship in male showing positive allometry. Carcinoscorpius rotundicauda (mangrove horseshoe crab) was found to co-occur in the study site. This study shows quite a small population size of T.gigas in Perak if compared to other estimates for T.gigas in the east coast. Therefore, conservation effort should be carried out in order to safeguard the existing population from decreasing.
v
VARIASI MORFOMETRIK DAN POPULASI BELANGKAS (Tachypleus gigas) DI TELUK SENANGIN, PERAK, MALAYSIA
ABSTRAK
Terdapat empat spesis belangkas di dunia dan tiga spesis boleh didapati di Malaysia. Populasi Tachypleus gigas telah diketahui wujud di Semenanjung Malaysia dan Borneo. Walau bagaimanapun, maklumat terhadap populasi T. gigas di pantai barat Malaysia adalah sangat terhad. Objektif kajian ini adalah untuk menganggarkan populasi dan mengukur parameter morfometrik belangkas (T. gigas) di Teluk Senangin, Perak, Malaysia. Kajian ini telah dijalankan pada Oktober 2014 and Januari 2015 dengan menggunakan kaedah tangkap-tanda-tangkap semula. Sampel telah ditandakan dengan butang tag bagi setiap tangkapan dan dilepaskan kembali ke habitat semula jadi mereka sebelum penangkapan semula dilakukan dengan selang satu hari selepas dibebaskan. Saiz populasi T. gigas di Teluk Senangin adalah antara 1743 hingga 10 385 individu dengan menggunakan formula Peterson yang diubahsuai oleh Chapman (1982). Purata jumlah panjang belangkas jantan adalah 34.79±1.83 cm dan betina adalah 38.50±7.34 cm. Purata berat belangkas jantan adalah 268.75±34.48 g dan betina adalah 573.0±204.62 g. Hubungan antara bahagian-bahagian badan bagi T.gigas di Teluk Senangin mendedahkan hubungan linear dalam kebanyakan kes. Semua perhubungan menunjukkan allometri negatif pada jantan dan betina kecuali hubungan Jumlah Panjang-Panjang Karapas pada belangkas jantan menunjukkan allometri positif. Carcinoscorpius rotundicauda (belangkas bakau) juga turut ditemui di tempat kajian. Kajian ini menunjukkan saiz populasi T. gigas di Teluk Senangin adalah kecil berbanding dengan populasi T. gigas di pantai timur. Oleh itu, usaha pemuliharaan perlu dilakukan untuk melindungi populasi yang sedia ada daripada berkurangan.
vi
TABLE OF CONTENTS Pages TITLE PAGE APPROVAL FORM DECLARATION ACKNOWLEDGEMENT ABSTRACT ABSTRAK TABLE OF CONTENTS LIST OF TABLES LIST OF FIGURES LIST OF ABBREVIATIONS LIST OF APPENDICES CHAPTER 1
CHAPTER 2
CHAPTER 3
CHAPTER 4
i ii iii iv v vi vii ix x xi xii
INTRODUCTION 1.1 Study background 1.2 Significance of study 1.3 Objective LITERATURE REVIEW 2.1 Natural history and taxonomy of horseshoe crab 2.2 The importance of horseshoe crab 2.3 Distribution of horseshoe crabs population 2.4 Methods of assessing population 2.5 Allometry study METHODOLOGY 3.1 Study site 3.2 Collection of samples 3.3 Capture – Mark – Recapture (CMR) method 3.4 Morphometric measurement 3.5 Calculation of population size using Chapman‟s Modified Peterson formula 3.6 Allometry relationship 3.7 Analyses of data RESULTS 4.1 Total captured and marked samples 4.1.1 Recaptured samples
vii
1 2 3
4 7 8 10 11
13 15 15 16 18 18 19
20 21
4.2 4.3 4.4 4.5 CHAPTER 5
CHAPTER 6
Estimated population size of horseshoe crabs Size of T. gigas Allometric relationship Other observations
21 22 23 26
DISCUSSIONS 5.1 The estimated population size of Tachypleus gigas in Teluk Senangin 5.2 General size of T. gigas 5.3 Allometry 5.4 Other observations 5.5 Conservation and management of horseshoe crabs
30 30 32 33
CONCLUSION
34
REFERENCES APPENDICES CURRICULUM VITAE
28
35 43 45
viii
LIST OF TABLES
Number of Tables 4.1 4.2 4.3 4.4 4.5
Pages
Captures of horseshoe crabs (T. gigas) in Teluk Senangin in October 2014 and January 2015 Population size for October 2014 and January 2015 Mean ±standard deviation and range of size parameter of Tachypleus gigas caught in Teluk Senangin, Perak Statistical analysis and morphometric relationship of different body measurements of T.gigas from Teluk Senangin Captures of horseshoe crabs (C. rotundicauda) in Teluk Senangin in October 2014 and January 2015
ix
22 22 23 25 26
LIST OF FIGURES
Number of Figures 1.1 2.1 2.2 3.1 3.2 3.3 3.4 3.5 4.1 4.2 4.3 4.4
Pages
Distribution of HSC in Peninsular Malaysia based on related reports Species of horseshoe crabs The oldest HSC fossil: Lunataspis aurora (left) and a modern HSC (right) The sampling site in Teluk Senangin, Perak, Malaysia Teluk Senangin beach Horseshoes crab marked with white button tag Summary of the measurement of body parameters Male horseshoe crab (left) and female horseshoe crab (right) Percentage of male and female T. gigas caught in Teluk Senangin, Perak Allometric relationship between W – TL in (a) male, (b) female T. gigas Allometric relationship between W – CW in (a) male, (b) female T. gigas Physical condition of horseshoe crabs (a) deformed telson, (b) & (c) damaged carapace, (d) barnacles infestation
x
2 6 7 14 14 16 17 17 21 25 26 27
LIST OF ABBREVIATIONS
Abbrevations C. rotundicauda CL cm CMR CW g HSC IOL km L. polyphemus LAL m N T. gigas T. tridentatus TAL TL W
Carcinoscorpius rotundicauda Carapace length centimeter Capture – Mark – Recapture Carapace weight gram Horseshoe Crab Inter-ocular length kilometre Limulus polyphemus Limulus Amoebocyte Lysate metre Population size Tachypleus gigas Tachypleus tridentatus Tachypleus Amoebocyte Lysate Total length Weight
xi
LIST OF APPENDICES
Appendix A
Page
Calculations of population size using Chapman‟s modified Peterson method
xii
47
CHAPTER 1
INTRODUCTION
1.1 Study Background Horseshoe crab (HSC) or known as the King Crab has been living on earth for more than 400 million years ago. This invertebrate animal is also considered as living fossil as they survived until this day with little modification of the morphology. Compared to other animals, HSC has only four species around the world. They are Limulus polyphemus, Tachypleus gigas, Tachypleus tridentatus and Carcinoscorpius rotundicauda. Limulus polyphemus is only found in Atlantic Ocean while the other three species can be found in Asia including Malaysia with T. tridentatus being available only in Borneo.
In Peninsular Malaysia, HSC can be found in coastal line of Terengganu, Pahang, Johor, Melaka, Negeri Sembilan, Selangor, Pulau Pinang and Kedah. These information are summarized in Figure 1.1. There are numerous studies on the general biology and life history of the horseshoe crab. However, the study on population size and allometry of HSC is very scarce in Malaysia, only a few places in the east coast of Peninsular Malaysia have been chosen as study sites and there is no reported study on the population size of HSC in the west coast of Peninsular Malaysia.
The population of HSC in Malaysia was higher and abundant, but the populations are believed to be shrinking as the fishermen admitted that the phenomena where HSC could be easily spotted abundantly spawning on beaches were last seen ten or twenty years ago.
To date, the active consumption by local people and the domestic market had lead to the decreasing of the population of HSC in Malaysia (Christianus and Saad, 2009). Development of coastal areas for resort, anthropogenic activities such as water sport and pollution also contribute to the decline of HSC population in Malaysia.
Figure 1.1 Distribution of HSC in Peninsular Malaysia based on related reports
1.2 Significance of Study Concern has arisen that HSC populations are declining. However, there are only a few reported studies on the population size of HSCs in Malaysia. To date, there is no reported study on the population size and allometry of HSCs in the Perak waters. Therefore, this study is carried out in order to provide useful baseline information to monitor the current population and the growth of HSCs, especially in Perak, Malaysia. This information makes an important basis for the conservation and management of HSC in the future.
2
1.3 Objective There are two objectives in this study:
To estimate the population size of the horseshoe crabs (Tachypleus gigas) in Perak, Malaysia by capture-mark-recapture (CMR) method.
To measure the morphometric parameters of the horseshoe crabs (Tachypleus gigas) in Perak.
3
CHAPTER 2
LITERATURE REVIEW
2.1 Natural History and Taxonomy of Horseshoe Crab Horseshoe crabs (Fig. 2.1) are ancient group of aquatic merostome arthropods which is closely related to trilobites. There are only four species of horseshoe crabs around the world and three species are found in coastal waters of Malaysia. They have survived for millions of years with little modification of the morphology. Few species exemplifies their designation as ecological generalists (Sekiguchi and Shuster, 2009). HSC is also known as living fossil because of its history that can date back at least to the Carboniferous Period, 245 million years ago. The oldest HSC fossil found is from 445 million year-old Ordovician age rocks in central and northern Manitoba which the researchers gave its scientific name Lunataspis aurora, meaning “crescent moon shield of the dawn” (Fig. 2.2).
Horseshoe crabs are the only marine arthropods that migrate from offshore depths to the intertidal zone to spawn during high tides of new and full moons throughout the year (Brockmann and Smith, 2009; Hajeb et al., 2009) but they tend to prefer warmer months for nesting (Akbar John et al., 2011). They come ashore as amplexed mated pairs and there are also multiple satellite unpaired males that will crowd around the nesting pairs to form spawning groups (Brockmann and Smith, 2009; Botton et al., 2010). The spawning time of horseshoe crabs may depend on the strong synchronization with high tides or high water levels (Brockmann and Smith, 2009).
Below is the classification of horseshoe crabs (IUCN, 2014). HSC is grouped into three genera in two families in the Superfamily Limulacea (Sekiguchi and Shuster, 2009): Kingdom: Animalia Phylum: Arthropoda Class: Merostomata Order: Xiphosura Family Limulidae Limulus polyphemus (Linnaeus) Family Tachypleinae Tachypleus tridentatus (Leach 1819) Tachypleus gigas (Muller 1785) Carcinoscorpius rotundicauda (Latreille 1802)
5
Figure 2.1 Species of horseshoe crabs (A: Males; C: Females): Top row (left to right): Limulus polyphemus and Carcinoscorpius rotundicauda; Bottom row (left to right): Tachypleus gigas and Tachypleus tridentatus (Tanacredi et al., 2009).
6
Figure 2.2 The oldest HSC fossil: Lunataspis aurora (left) and a modern HSC (right) (Source: Royal Ontario Museum, 2008).
2.2 The Importance of Horseshoe Crab Horseshoe crabs are ecologically important in coastal and estuarine communities. They are omnivorous, feeding on variety of benthic invertebrates including bivalves, gastropods, crustaceans, polychaetes and miscellaneous food items (including insects, amphipods, isopods and foraminifera) (Chatterji et al., 1992; Akbar John et al., 2012). HSC eggs serve as the primary food for many species of migratory shorebirds and invertebrates. There are reports of loggerhead turtles feeding on adult HSC (Wallace et al., 2009) and hermit crabs feeding on trilobites and second instar of HSC (Botton, 2009). There are strong relationship between the density of HSC eggs and the abundance of shorebirds. In America, a rough estimation showed that a population of 40 000 shorebirds would need to consume approximately 16 billion eggs to survive (Botton, 2009).
7
Therefore, the population of HSC is crucial in order to produce that amount of eggs for the consumption of the shorebirds. High density of eggs can attract more shorebirds and contributing to the ecotourism of one particular area.
Horseshoe crab is also medically important. Their blood can produce Limulus Amoebocyte Lysate (LAL) or Tachypleus Amoebocyte Lysate (TAL) that can be used in pharmaceutical industry to detect and quantify endotoxin of Gram-negative bacteria (Akbar John et al., 2011) in biological, pharmaceutical drugs, and medical devices. LAL provides a rapid and indirect test for measurement of bacteria which could also can be used to study bacteria in sediments as well as in shore waters (Novitsky, 2009). Large amount of horseshoe crab‟s blood is needed for these commercial uses.
In America, the horseshoe crabs were used in agriculture. The dead bodies of horseshoe crabs are hauled up in wagons for manure and the people believed that it can enrich the soil and add greatly to increase the crops. In the mid-1800s, the Americans used composted HSC to fertilize plants in the peach orchard (Shuster, (2003) in Kreamer and Michels, 2009). Besides that, farmers also used the crabs as food for their livestock feed. Masses of HSC were harvested in the late 1800s and early 1900s when the farming industry was developed (Shuster, (2003) in Kreamer and Michels, 2009). HSC also used in the fisheries industry as bait for whelk, eel, catfish, minnow and killifish (Kreamer and Michels, 2009). HSC is also consumed by human as delicacies in restaurants. Normally the female HSC was consumed for their eggs. This also contribute to the economy as one female cost RM 2 (USD 0.50) and the cost can reach as high as Baht 120 (USD 3) in Thailand (Christianus and Saad, 2007).
2.3 Distribution of Horseshoe Crabs Population The population of HSC is believed to be shrinking while the distribution is often interrupted. Their populations vary in numbers in different ranges (Sekiguchi and Shuster, 2009). In recent years, there are many countries conducting research on the population size of HSC. From all those reports, the conclusion is showing that the population of HSC is in an alarming state.
8
There are several studies throughout the world especially in America (Sekiguchi, 2009) and Asia including China (Hu et al., 2009), Hong Kong (Shin et al., 2009), Taiwan (Chen et al., 2004), India (Chatterji et al., 1992), Singapore (Cartwright-Taylor et al., 2009; 2011; Cartwright-Taylor and Hsu, 2012), Philippines (Almendral and Schoppe, 2005) and Malaysia (Tan et al., 2011; 2012). The population of the American horseshoe crab, L. polyphemus is much more abundant than the other three species in other countries. The population of American HSC is estimated to be 15 760 in Florida Gulf Coast (Brockmann and Johnson, 2011) and 19 million in Delaware Bay (Smith et al., 2006). However, the population in the country is believed to decline in recent years due to the active harvest for bait and biomedical applications (Kreamer and Michels, 2009).
The other three species of HSCs can be found along the Asian coastal lines. In China, an intensive population distribution investigation of juvenile T. tridentatus showed that the population of juvenile is very little in the country (Hu et al., 2009). The HSCs are „Grade II Protected Animal of China‟ in the „List of State Key Protected Wildlife‟ (Yang et al., 2009).
In Hong Kong, juvenile horseshoe crabs were reported to be reduced by over 90% in density since 2002 (Shin et al., 2009). HSCs in Hong Kong are sold to the fish wholesale markets and seafood restaurants. Majority of the HSCs are used for the Chinese traditional „set-free‟ rituals that practiced by Buddhist at sea, while the remaining will be kept and served as delicacy dishes in restaurants (Shin et al., 2009).
In Taiwan, T. tridentatus exhibits population subdivision over a relatively small geographic range (Yang et al., 2007). T. tridentatus and T. gigas were once relatively abundant along the coastal line of Taiwan, however, the population is locally endangered due to overfishing, water pollution and land reclamation (Chen et al., 2004).
T. gigas and C. rotundicauda are distributed along the northeast coast of India extending from the extreme north of West Bengal through Orissa to the northern coast of Andhra Pradesh (Mishra, 2009). There is still lack of information on the population in India. The
9
main threat to the HSC in India is the destruction of beaches where the adults spawn (Mishra, 2009).
In Singapore, T. gigas and C. rotundicauda can be found (Cartwright-Taylor et al., 2009; 2011; Cartwright-Taylor and Hsu, 2012). The population of these two species were once abundance in the country, yet, the first study on HSC distribution and abundance in habitat was only be conducted in 2011 (Cartwright-Taylor et al., 2011). These two species were abundant on the beaches of Singapore in the 1950s and 1960s (Cartwright-Taylor et al., 2011). Today, these species are in critically endangered state due to land reclamation and coastal development (Davidson et al., 2008). Juveniles are more abundant than the adult HSC in Singapore (Cartwright-Taylor and Hsu, 2012). While in Philippines, 125 juveniles of T. tridentatus were reported but there are no studies on adult HSC (Almendral and Schoppe, 2005).
The three species of HSCs (T. gigas, T. tridentatus and C. rotundicauda) can be found in Malaysia. T. gigas and C. rotundicauda can be found along the coastal lines in Peninsular Malaysia, while T. tridentatus can be found in Borneo (Ismail and Sarijan, 2011). Population of T. gigas in Malaysia coastline is less studied. There are only a few reported studies on nesting ground and spawning of T. gigas in East Coast of Peninsular Malaysia especially in Pahang and Terengganu. Balok and Pekan (Pahang) were identified as the nesting grounds of T. gigas. The total population size of T. gigas was estimated at 1387 to 584 210 in Pahang (Afilia, 2013; Nurshamimi, 2013).
2.4 Methods of Assessing Population Capture-mark-recapture (CMR) method is a common method used to estimate the size of the population of animals that are easily captured. Bailey‟s triple-catch method and Chapman‟s modified Peterson method can minimize statistical bias of estimated abundance. Bailey‟s triple-catch method is simple and suitable for open populations (Henderson, 2003). CMR method has been used on population size study of lobster (Evan and Lockwood, 1994) and Lake Erie watersnake (King et al., 2006). This method is suitable for the calculation to estimate population size of HSC from the CMR data that
10
will obtained from three or four sampling occasions. There are four assumptions for this method (Henderson, 2003): 1. The marked animals are not affected either in behaviour or life expectancy by being marked and the marks will not be lost. 2. The marked animals become completely mixed when released back into the population. Slow-moving or highly territorial animals are unsuitable for capture-recapture methods, as they do not move sufficiently to re-mix after marking. 3. The probability of capturing a marked animal is the same as that of capturing any member of the population. 4. Sampling must be at discrete time intervals and the actual time involved in taking the samples must be small in relation to the total time.
2.5 Allometry study The word “allometry” first termed by Huxley and Teissier in 1936 in the study of relative growth (Huxley and Teissier, 1936). Allometry studies describe the changes in relative dimensions of parts of the body that are correlated with changes in overall size or in most general sense, allometry is the study of the relationship between size and shape of an animal. Huxley and Teissier proposed the algebraic formula of allometric growth: 𝑦 = 𝑏𝑥 𝛼 , where x represents a variable to which the allometrically growing part y is related. The α is known as the allometric coefficient. If α is greater than 1, then it means the allometric organ y is growing faster than x and it is called the positive allometry; when α is less than 1, it is called the negative allometry; and when α = 1 is known as isometry, and implies that the ratio of y and x is constant in the measured interval. This equation is widely used in biology and ecology to describe the relationship between the physiological components of an organism.
There are at least four different concepts of allometry which can be characterized as “dynamic” and “static”. (1) ontogenetic allometry, which refers to relative growth in
11
individuals and (2) phylogenetic allometry, which refers to constant differential growth ratios in lineages are characterized as “dynamic” while (3) intra-specific allometry, which refers to adult individuals within a species or a given local populations and (4) interspecific allometry, which refers to the same kind of phenomenon among related species are characterized as “static” (Gould, 1966).
It is a well known fact that many aquatic animals change their body proportions even shape if they inhabit in different places (Gaspar et al., 2002). Chatterji et al. (1988) suggested that the allometric relationship in horseshoe crab plays an important role in understanding the comparative morphometric variation in the population. Understanding of allometry in shell and soft body parts of the crabs define the growth of the species (Chatterji et al., 1988). Moreover, the allometric relationship also provides important information regarding comparative growth of various body parameters of an individual. In the latest study, Chatterji and Pati (2014) suggested that by using the allometric tool, it can help in converting the body parameter with one another and it is also useful in getting the valuable information on general well being of the animal, stock assessment models, estimation of biomass and comparing the life histories of species from different regions. In the studies of HSCs, different body parameters such as body weight, carapace width, carapace length, telson length and total length have been studied (Vijayakumar et al., 2000; Srijaya et al., 2010; Sahu and Dey, 2013; Chatterji and Pati, 2014).
12
CHAPTER 3
METHODOLOGY
3.1 Study site The study was conducted in Teluk Senangin (N 04° 19.397‟ E 100° 33.018‟) in Perak located at the west coast of Peninsular Malaysia (Fig. 3.1). Teluk Senangin is located around 26 km from Lumut. Lumut is a coastal town as the gateway to Pulau Pangkor. Teluk Senangin is a recreational beach and it is an area for the fisherman to harvest the crabs (Fig. 3.2). This site was selected based on the reported sightings and capture of horseshoe crabs by local people and fisherman. The study was conducted on October 2014 and January 2015. Interview with local fisherman is done during the first visit.
Figure 3.1 The sampling site in Teluk Senangin, Perak, Malaysia (Source: Google Map, 2015)
Figure 3.2 Teluk Senangin beach
14
3.2 Collection of samples The sampling process was done at open sea area by boat with the help from hired fisherman. Crabs nets were lowered 24 hours before the capture was done. The journey took around 15 minutes to reach the net lowering area which is around 4 km from the shore. The net used was 92 m in length and 1.5 m in width with 5 inch of mesh size. A total of 2 sets of nets were used in the sampling. The species of HSC and the physical conditions was recorded. The same collection of samples was used for two purposes: i) population size determination using CMR method, and ii) morphometry studies. 3.3 Capture – Mark – Recapture (CMR) Method Capture-mark-recapture (CMR) method was used in this study. The CMR method was done two times in October 2014 and three times in January 2015. The interval of one catch to another catch was one day.
All the samples of T. gigas were captured in the morning around 7 am. The HSC were removed properly from the net as they get tangled in the net. Then the trapped samples were gathered into a big container and brought back to the shore for the tagging process. Each sample of T. gigas was tagged by a white button tag at the dorsal edge of the prosomal as shown in Figure 3.3. Later, all the tagged samples were released to the original capture place after the tagging process was done. After one day, the second catch was carried out at the same time as the first catch period. The tagged HSC that been caught will be the recaptured sample. Similar technique was used in the second sampling occasion (January 2015).
15
Figure 3.3 Horseshoes crab marked with white button tag.
3.4 Morphometric measurement A total of five body parameters were measured in this study (Fig. 3.4). There were total length (TL) which is from the tips of carapace to the tips of telson, carapace length (CL), carapace width (CW), inter-ocular length (IOL) and weight (W). The length measurements were measured to the nearest cm by using measurement tape as shown in figure 3.4. The weight was weighted to the nearest 0.01 g by using an electronic scale (Apex digital electronic scale A2000-1). All the measurements were conducted on a flat surface to avoid parallax error. The sex was also determined by observing the presence or absence of monodactylus at the first pair of pedipalps. The monodactylus pedipalps are absent in female and present in male (Fig. 3.5).
16
Figure 3.4 Summary of the measurement of body parameters
Figure 3.5 Male horseshoe crab (left) and female horseshoe crab (right)
17
3.5 Calculation of population size using Chapman’s modified Peterson method A total of 46 individuals were captured during the study. All the data recorded from CMR method were calculated by using Chapman‟s modified Peterson method. This formula is the most suitable formula for the estimation of population size in this study because the formula had been modified to meet the assumptions thus providing a better estimation (Henderson, 2003). The calculation was separated according to the month of sampling. Below are the formula of Chapman‟s modified Peterson method:
a) Estimated population size, N: 𝑁=
𝑀+1 𝐶+1 −1 𝑅+1
b) Variance, Var: 𝑉𝑎𝑟 =
𝑀 + 1 𝐶 + 1 𝑀 − 𝑅 (𝐶 − 𝑅) 𝑁 𝑀 − 𝑅 (𝐶 − 𝑅) = 𝑅 + 1 2 (𝑅 + 2) 𝑅 + 1 (𝑅 + 2)
c) Standard error, S.E.: 𝑆. 𝐸. = √𝑉𝑎𝑟 d) Population range (95% confidence level): 𝑁 + (𝑆. 𝐸. ) e) Total estimated population size, P: 𝑃 = 𝑁 + 𝑉𝑎𝑟 Where; N = Estimated of population size M = Total number of captured and marked samples on first catch C = Total number of captured and marked samples on second catch R = Number of captured samples on the first catch that were then recaptured on the second catch
3.6 Allometry relationship The data collected in adult (excluded juveniles, deformed and damaged individuals) on lengths and weight of both sexes were analysed by using the formula of allometric growth:
18
𝑦 = 𝑏𝑥 𝛼 . The estimation of the allometric relationships between different body parameters was made by adjustment of a linear function to the data: 𝑙𝑜𝑔 𝑦 = 𝛼 log 𝑥 + log 𝑏 Where; y = total length (TL), carapace width (CW) or carapace length (CL) x = weight (W), total length (TL) or inter-ocular length (IOL) α = slope of line (allometric coefficient) b = intercept of the line on the y – axis
Major axis regression was carried out using software PAST v2.17c (Hammer et al., 2001). The significance of the slope was tested by means of a t-test (Zar, 1999). The morphometric variables were divided into three categories: positive allometry (α > 1); negative allometry (α < 1); and isometry (α = 1). The association degree between the body parameters was calculated by the correlation coefficient (r).
3.7 Analyses of data Fisher‟s exact test was used to analyse the significant difference between total male and female that had been captured since the sample size was small (Quinn and Keough, 2002).
19
CHAPTER 4
RESULTS
4.1 Total captured and marked samples A total of 46 individuals of T. gigas were captured in Teluk Senangin throughout the study period. The total number of horseshoe crabs collected were similar in October 2014 and January 2015 which is 23 individuals. The number of males and females collected from the two months are also the same as male collected was 14 individuals and female collected was 9 individuals (Table 4.1). The sex ratio of the population was 1.56:1. The number of male and female captured between sampling month has no significant difference (P > 0.05, Fisher‟s exact test).
39% male
61%
female
Figure 4.1 Percentage of male and female T. gigas caught in Teluk Senangin, Perak
4.1.1 Recaptured samples During the whole sampling period, a total of 46 individuals were captured, marked and released back to their natural population. There was only one recapture in October 2014. However, three times of catch done in January 2015 resulted in no recaptured horseshoe crab (Table 4.1).
4.2 Estimated population size of horseshoe crabs Since the population was small and there is no recapture in January 2015, Chapman‟s modified Peterson method was used. The population size for October 2014 was 1743 and January was 10 385 (Table 4.2). Thus, the total estimated population size (P) in Teluk Senangin range from 1743 to 10 385.
21
Table 4.1 Captures of horseshoe crabs (T. gigas) in Teluk Senangin in October 2014 and January 2015 Sampling Occasions Catch
October 2014
January 2015
Male
Female
Total
Recapture
Male
Female
Total
Recapture
First
8
5
13
-
7
5
12
-
Second
6
4
10
1
7
4
11
0
Third
-
-
-
-
0
0
0
0
Total
14
9
23
1
14
9
23
0
- : no sampling occurs Table 4.2 Population size for October 2014 and January 2015 Month
Estimated
Variance (Var)
Population Size
Standard Error
Total Estimated
(S.E)
Population Size
(N)
(P = N + Var)
October 2014
83
1660
40.743
1743
January 2015
155
10230
101.143
10385
4.3 Size of T. gigas Table 4.3 shows the summary of the mean and range size of male and female body parameters caught in Teluk Senangin. The average total length for male was 34.79±1.83 cm and female was 38.50±7.34 cm.
22
The average carapace width of male horseshoe crabs was 16.13±0.79 cm, range from 14.8 cm to 17.5 cm. For the female horseshoe crabs, the average width of the carapace was 18.85±2.71 cm, range from 12.5 cm to 21.4 cm.
For the telson length, the male horseshoe crabs showed the range size of 15 cm to 19.4 cm with a mean size of 17.81±1.33 cm, meanwhile 10.3 cm to 23.7 cm with a mean of 18.47±3.99 cm in female horseshoe crabs.
For the body weight, the largest male was 345 g and the largest female was 815 g. the average weight for male horseshoe crabs was 268.75±34.48 g, meanwhile the average weight for female horseshoe crabs was 573.0±204.62 g. This showed that females were much heavier than males. Overall, female individuals were bigger than the males individuals.
Table 4.3 Mean ± standard deviation and range of size parameter of Tachypleus gigas caught in Teluk Senangin, Perak Size Parameter
Male
Female
Total Length (cm)
34.79±1.83 (32.0 – 38.7)
38.50±7.34 (21.3 – 47.6)
Carapace Width (cm)
16.13±0.79 (14.8 – 17.5)
18.85±2.71 (12.5 – 21.4)
Telson Length (cm)
17.81±1.33 (15.0 – 19.4)
18.47±3.99 (10.3 – 23.7)
Body Weight (g)
268.75±34.48 (220.0 – 345.0)
573.0±204.62 (135.0 – 815.0)
4.4 Allometric relationship The relationship between various body parts of T.gigas captured in Teluk Senangin reveal linear relationship in most cases (Table 4.4). All relationship showed negative allometry in male and female except for the total length – carapace length relationship in male showing positive allometry with the α value of 1.541 and the r value was also strong (r =
23
0.68). However, total length – carapace length relationship in female was a negative allometry (α = 0.377) and has a moderate r value (r = 0.51). The weight – total length relationship in male was significant and has a high degree of correlation (r = 0.55), with α value 0.232 (Fig. 4.2a). However, the weight – total length relationship in female was not significant (P > 0.05, t-test) (Fig. 4.2b). The weight – carapace width relationship in male was significant (P < 0.05, t-test) with a high degree of correlation (r = 0.77). The α value is 0.289 showing that it is a negative allometry (Fig. 4.3a) indicated that the increase in body weight was associated with carapace width. In female, the relationship was significant (P < 0.05, t-test) and has a high degree of correlation (r = 0.71), with the α value of 0.246 showing that it is also a negative allometry (Fig. 4.3b). The total length – carapace width relationship in male was significant (P < 0.05, t-test) with a high degree of correlation (r = 0.75) and an α value of 0.911 that is almost reaching 1. In female population, the relationship was significant (P < 0.05, t-test) with a high degree of correlation (r = 0.69) and α value of 0.28. The inter-ocular length – carapace width relationship were significant (P < 0.05, t-test) in male and female population. The degree of correlation between male and female were almost the same which is r = 0.58 and r = 0.54 respectively. Both populations show negative allometry with α = 0.373 and α = 0.549.
24
Table 4.4 Statistical analysis and morphometric relationship of different body measurements of T. gigas from Teluk Senangin Parameters
Male
Female
AC(α)
CC (r)
S
Relationship
AC(α)
CC (r)
S
Relationship
W:TL
0.232
0.55
S
- allometry
0.689
0.37
NS
- allometry
W:CW
0.289
0.77
S
- allometry
0.246
0.71
S
- allometry
TL:CL
1.541
0.68
S
+ allometry
0.377
0.51
S
- allometry
TL:CW
0.911
0.75
S
- allometry
0.28
0.69
S
- allometry
IOL:CW
0.373
0.58
S
- allometry
0.549
0.54
S
- allometry
AC= Allometric coefficient, CC= Correlation coefficient, W= Weight, TL= Total length, CW= Carapace width, CL= Carapace length, IOL= Inter-ocular length, S= Significant, NS= Not
1.7
1.7
1.65
1.65 y = 0.232x + 0.978 R² = 0.30
1.6
Log Total Length (cm)
Log Total Length (cm)
significant
1.55 1.5
1.6 1.55 1.5 1.45
1.45
1.4
1.4 2.25
a
y = 0.689x - 0.331 R² = 0.13
2.3
2.35
2.4
2.45
2.5
2.55
2.7
2.6
Log Weight (g)
b
2.75
2.8
2.85
Log Weight (g)
Figure 4.2 Allometric relationship between W – TL in (a) male, (b) female T. gigas
25
2.9
2.95
1.4
1.35
1.35 y = 0.289x + 0.508 R² = 0.59
1.3
Log Carapace Width (cm)
Log Carapace Width (cm)
1.4
1.25 1.2 1.15 1.1 1.05
y = 0.246x + 0.609 R² = 0.50
1.3 1.25 1.2 1.15 1.1 1.05
1
1 2.25
2.3
2.35
2.4
2.45
2.5
2.55
2.6
Log Weight (g)
a
2.7
2.75
2.8
2.85
2.9
2.95
Log Weight (g)
b
Figure 4.3 Allometric relationship between W – CW in (a) male, (b) female T. gigas
4.5 Other observations During sampling, physical condition of horseshoe crabs were observed. Some of the caught T. gigas were physically deformed (Fig. 4.4a) and damaged (Fig. 4.4b-c). Some of them were infested with barnacles (Fig. 4.4d). C. rotundicauda was also found in the same place where T. gigas were collected. Seven female C. rotundicauda individuals were observed during the sampling (Table 4.5)
Table 4.5 Captures of horseshoe crabs (C. rotundicauda) in Teluk Senangin in October 2014 and January 2015 Month
Sex Male
Female
October 2014
0
6
January 2015
0
1
Total
0
7
26
a
b
c
d
Figure 4.4 Physical condition of horseshoe crabs (a) deformed telson, (b) & (c) damaged carapace, (d) barnacles infestation
27
CHAPTER 5
DISCUSSIONS
5.1 The estimated population size of Tachypleus gigas in Teluk Senangin A total of 46 individuals of Tachypleus gigas were caught with the total estimated population size ranged from 1743 to 10 385 individuals in Teluk Senangin, Perak. This large range of number indicated that the population was an open population which allowed immigration and emigration throughout the period. Most of the studies on population of T. gigas were conducted in the east coast of Peninsular Malaysia. In 2013, the population study conducted in Pahang showed that the total estimated population size ranged between 1387 to 584 210 individuals in Sungai Ular (Afilia, 2013) and 9880 to 305 704 individuals in Tanjung Api (Nurshamimi, 2013). From the previous reports, the population in Teluk Senangin is smaller than the population in the east coast of Peninsular Malaysia. So far, the population study on T. gigas is still scarce in Malaysia.
The sex ratio of the population in Teluk Senangin was 1.56:1 which male consists of 61% and female consists of 39% of the population. This showed that the male outnumbered the female. However, the sex is not influenced by the months of sampling in Teluk Senangin. A few reports also showed that male-biased in the population of HSC (Tan et al., 2012; Afilia, 2013; Nurshamimi, 2013). This higher sex ratio in males was common for the horseshoe crab population because male tends to re-visit the nesting beach more frequently than the female (Tan et al., 2012). The larger number of male population may
be due to the overharvest of female as the eggs are consumed as local delicacies in Teluk Senangin.
There is only one recapture throughout the study which is in October 2014. The small sample size and the very low recapture rate may cause the result to be upwardly biased estimates (Thomas & Krebs, 1997). Therefore, a modified estimation method – Chapman‟s modified Peterson method was used to overcome this problem. The Chapman‟s modified Peterson formula was applied separately for each of the two periods of samplings. This method was used in the study on the abundance of horseshoe crab, L. polyphemus in Delaware Bay by Smith et al. (2006). The low recapture rate in October 2014 and no recapture in January 2015 might be due to the large population size of T. gigas in the open sea of Teluk Senangin. No recapture on January 2015 might also be due to the movement of HSC along the coast for feeding activity since it is an open sea. The recapture probability might be influenced by the effect of trap shyness because the net lowered was around the same location throughout the sampling period. The animal may reluctant to enter the trap again or avoiding the same location once being caught. Besides that, short time interval between each catch might be one of the reasons for the absence of recapture sample.
Surprisingly, there was no capture on the third sampling of January 2015. Besides no capture for HSC, there was also no capture for crabs by fishermen. Tidal rhythm and lunar rhythm are important factors that contributed in the capture of HSC that visit the intertidal zone (Palmer, 1990; Chabot and Watson, 2010). According to the tide table and solunar chart on that day, there was a high tide in the morning when sampling activity was carried out and the solunar chart showed that the activity of fishes was very low on that day. The lunar phase on that day is waxing crescent which is not a full moon. Therefore, the activity of HSC might be in the deep water rather than the shallow water where the net was lowered. Water temperature and salinity will also affect the activity of HSC in the water. Unfortunately, the physicochemical parameters were missed out during the whole sampling period.
29
5.2 General size of T. gigas In general, the average of the total length of T. gigas collected in Teluk Senangin was 34.79±1.83 cm for male and 38.50±7.34 cm for female. The average total length reported in Tanjung Api, Pahang was 32.86 cm for male and 40.31 cm for female (Nurshamimi, 2013) while the average total length reported in Sungai Ular, Pahang was 32.35 cm for male and 34.08 cm for female (Afilia, 2013). The study in Balok, Pahang showed that the average total length of T. gigas was 20.29 cm for male and 26.02 cm for female (Tan et al., 2012). For the carapace width, the samples from Teluk Senangin were 16.13±0.79 cm for male and 18.85±2.71 cm for female. The average carapace width length reported in Tanjung Api was 17.12 cm for male and 20.68 for female (Nurshamimi, 2013). The average carapace width length reported in Sungai Ular was 17 cm for male and 17.31 cm for female (Afilia, 2013). Meanwhile, Tan et al. (2012) reported the average carapace width in Balok was 19.12 cm for male and 24.68 cm for female. From those results, it can be concluded that the total length of T. gigas in west coast is greater than the T. gigas in east coast. However, the carapace width of T. gigas in west coast is smaller than the T. gigas in east coast. In conclusion, female is larger than male in T. gigas and it showed that female-biased sexual size dimorphism in HSC.
5.3 Allometry The result found in this study is the negative allometry for both the males and females in all relationships except the TL – CL relationship in males. TL – CL relationship showed a positive allometry in males, reflected that the CL increases proportionally with the gradual increase of the TL. The same result was also reported by Vijayakumar et al. (2000) but Sahu and Dey (2013) reported a different result. Conversely, females have a negative allometry of growth and higher magnitude of the growth rate in TL than CL. In the TL – CW relationship in males and females, it shows negative allometry which reflected the rate of total length increase was higher magnitude than that of carapace width. The α value of males is 0.911 that is almost reaching 1 (indicating isometric growth). The TL – CW relationship reported by Vijayakumar et al. (2000) was uniform growth.
30
The W – TL relationship in males was negative allometry, indicated that the rate of the body weight increase was of higher magnitude than that of total length. Similar results were also obtained by others (Vijayakumar et al., 2000; Tan et al., 2012; Sahu and Dey, 2013). However, the W – TL relationship in female was not significant (P > 0.05, t-test). The W – CW relationship in males and females showed negative allometry with almost the same degree of correlation (r = 0.77 and r = 0.71 respectively), indicated that the increase in body weight was associated with carapace width. Similar result was also reported by Vijayakumar et al. (2000). The length – weight relationship may vary in different population as the water temperature, food availability, habitat type and reproductive activities are different in different areas (Tan et al., 2012). From the results, the habitat of the T. gigas in Teluk Senangin possibly similar as reported in Vijayakumar et al. (2000). However, the detail of the study site in Vijayakumar et al. (2000) paper was not mentioned. The IOL – CW relationship in males and females were negative allometry, indicated that the rate of IOL increase was in higher magnitude than CW. When the CW increases, the IOL will also increase showing that the IOL position was not fixed during the growth period. However, the allometry study on IOL with other body parameters were only reported by Sekiguchi et al. (1988) and Chen et al. (2010). Sekiguchi et al. (1988) reported that the growth rate of T. gigas was 1.28 on average. The IOL – CW relationship of T. tridentatus was isometric (α = 0.9591, b = 0.6201, 𝑟 2 = 0.9962) as reported in Chen et al. (2010). Therefore, more study on allometry of IOL with other body parameters should be conducted to ensure a better understanding on the growth of HSC.
By using the allometric tool, it can help in converting the body parameter with one another and provide the data to estimate the age of the HSC (Sekiguchi et al., 1988). In the present study, the total length of the HSC was considered as a reference for comparing relationships with different body parts. Relationships between W – TL, W – CW, TL – CL, TL – CW and IOL – CW were found linear in this study. The size and total length will increase with the increase in the age of the HSC as the animal grew older, the values of carapace width will exceed carapace length (Vijayakumar et al., 2000). The allometric
31
relationship among various parts of the body is functionally important in the biology of the organism and particularly serve as a predictive tool for ecological investigations (Srijaya et al., 2010).
5.4 Other observations A few adult horseshoe crabs were infested with barnacles on their carapace. Majority of the infested individuals were males. Adult male is prone to the barnacles infestation compared to female as the females molt more frequent than males (Tan et al., 2011). Adults were also having higher chance to be infested because juveniles molt more frequent. Epibiont infestation may reduce the mobility of hosts as the barnacles on the carapace increased the weight of the HSC. Barnacles that encrusted the horseshoe crab‟s appendages will also affect the movement of the animal. This may increase the mortality of HSC. The barnacle infestation on horseshoe crabs in Teluk Senangin indicated that the animal was not healthy. Barnacles may impair the function of some organs on HSC such as eyes, gills and appendages (Botton, (1981) in Botton, 2009). The barnacles may also impair the growth of horseshoe crab. However, the exact number of infested horseshoe crab was not calculated therefore the real health condition of the animal in Teluk Senangin is not available in this study.
C. rotundicauda, the mangrove species of HSC was found in Teluk Senangin during the study. There are mangrove areas around Lumut, Segari and Pasir Panjang, Perak. Scientist believed that these two species co-exist with one another. Chatterji (1999) and Mishra (2009) have reported the co-existence of T. gigas and C. rotundicauda in east coast of India. In this study, the salinity of the water body was not measured. However, in general, the salinity in west coast is lower than the east coast (Hii et al., 2006; MohdAkhir et al., 2014). Therefore, the co-existence of T. gigas and C. rotundicauda might not easily been found in the east coast of Peninsular Malaysia due to the low tolerance of C. rotundicauda in high salinity water.
32
5.5 Conservation and management of horseshoe crabs This study provided the information on the estimated population size of T. gigas in the west coast of Peninsular Malaysia which is crucial for the conservation management planning in future. To date, no conservation practices, legislation or harvest regulations is implemented to protect the HSC in Malaysia. We believed that the population of HSC is decreasing after some local people mentioned that there were plenty of HSC can be capture during the 80‟s and 90‟s. The decline of the population is largely due to loss of suitable habitat caused by anthropogenic activities such as land reclamation, dike construction, water pollution, and loss due to overfishing for food consumption and biomedical use.
Potential breeding site for HSC are mostly flat, muddy or sandy shores with minimal human disturbances. Habitat destruction and water pollution caused by continuing urban developments in the hinterland of the shores and coastal infrastructural projects are the possible major factors leading to such declines. To protect the breeding ground of HSC, theses shore should be designated as Sites for Special Scientific Interest by the government, so that the urban development at these shores can be kept minimal (Shin et al., 2009). Conservation strategy: public education and awareness, ban of human consumption, and introduction of artificial breeding programs should be developed to prevent eventual loss of HSC (Shin et al., 2009). Implementation of habitat mitigation and restoration should be itemized in the national biodiversity conservation program.
Estimation of the population size of HSC is important to the Tachypleus Amoebocyte Lysate industry to determine the capacity of HSC that can be harvested in the sea. This may avoid over exploitation and contribute to the sustainable management of this valuable natural resource.
33
CHAPTER 6
CONCLUSION
This study provided the estimation population size and the allometric of T. gigas. The results show that the population in Teluk Senangin is medium with an estimated population size from 1743 to 10 385 individuals.
The allometry study provided the data on the growth of different body parts of T. gigas in Teluk Senangin. The relationships between various parts of T. gigas captured in Teluk Senangin reveal linear relationship in most cases. Only the W – TL relationship in female is not significant. W – CW relationship has the strongest relationship compared to the others. Therefore, it can serve as a predictive tool for the ecological investigations.
Further study should be done in the area on the migration, feeding activity, epibiont infestation and nesting behaviour of T. gigas in west coast of Peninsular Malaysia in order to develop a more complete data on T. gigas in Malaysia. Besides that, study on the mangrove species, C. rotundicauda should also be done since there are many mangrove areas in the west coast of Peninsular Malaysia.
Physicochemical parameters such as water temperature, water pH, salinity, sea current flow and the sediment on the sea floor should be taken for obtaining additional information in the study.
REFERENCES
Afilia, F.B. 2013. Horseshoe crabs (Tachypleus gigas) population size in Sungai Ular, Pahang, Peninsular Malaysia. Undergraduate thesis, Bachelor of Applied Science (Conservation and Management of Biodiversity), Faculty of Science and Technology, Universiti Malaysia Terengganu. 44p. Akbar John, B., Jalal, K.C.A., Zaleha, K., Armstrong, P. & Kamaruzzaman, B.Y. 2011. Effects of blood extraction on the mortality of Malaysian horseshoe crab (Tachypleus gigas). Marine and Freshwater Behaviour and Physiology 44(5): 321-327. Akbar John, B., Kamaruzzaman, B.Y., Jalal, K.C.A. & Zaleha, K. 2012. Feeding ecology and food preferences of Carcinoscorpius rotundicauda collected from the Pahang nesting grounds. Sains Malaysiana 41(7): 855-861. Almendral, M.A. & Schoppe, S. 2005. Population structure of Tachypleus tridentatus (Chelicerata: Merostomata) at a nursery beach in Puerto Princesa City, Palawan, Philippines. Journal of Natural History 39(25): 2319-2329. Botton, M.L. 2009. The ecological importance of horseshoe crabs in estuarine and coastal communities: a review and speculative summary. In. Tanacredi, J.T., Botton, M.L. & Smith, D.R. (Eds.), Biology and conservation of horseshoe crabs. New York: Springer Science and Business Media. pp 45-64. Botton, M.L., Tankersley, R.A. & Loveland, R.E. 2010. Developmental ecology of the American horseshoe crab Limulus polyphemus. Current Zoology 56(5): 550-562.
Brockmann, H.J. & Johnson, S.L. 2011. A long-term study of spawning activity in a Florida Gulf coast population of horseshoe crabs (Limulus polyphemus). Estuaries and Coasts 34:1049-1067. Brockmann, H.J. & Smith, M.D. 2009. Reproductive competition and sexual selection in horseshoe crabs. In. Tanacredi, J.T., Botton, M.L. & Smith, D.R. (Eds.), Biology and conservation of horseshoe crabs. New York: Springer Science and Business Media. pp 199-221. Cartwright-Taylor, L. & Hsu, C.C. 2012. Follow-up study on population structure and breeding pattern of the mangrove horseshoe crab Carcinoscorpius rotundicauda in Singapore. Aquatic Biology 14: 217-222. Cartwright-Taylor, L., Lee, J. & Hsu, C.C. 2009. Population structure and breeding pattern of the mangrove horseshoe crab Carcinoscorpius rotundicauda in Singapore. Aquatic Biology 8: 61-69. Cartwright-Taylor, L., Yap, V.B., Hsu, C.C. & Lou, S.T. 2011. Distribution and abundance
of
horseshoe
crabs
Tachypleus
gigas
and
Carcinoscorpius
rotundicauda around the main island of Singapore. Aquatic Biology 13: 127-136. Chabot, C.C. & Watson, W.H. 2010. Circatidal rhythms of locomotion in the American horseshoe crab Limulus polyphemus: underlying mechanisms and cues that influence them. Current Zoology 56(5): 499-517. Chatterji, A. & Pati, S. 2014. Allometric relationship in the adult population of the Malaysian horseshoe crab (Tachypleus tridentatus; Leach). International Journal of Research 1(11): 1378-1385. Chatterji, A., Mishra, J.K. & Parulekar, A.H. 1992. Feeding behaviour and food selection in the horseshoe crab, Tachypleus gigas (Müller). Hydrobiologia 246: 41-48. Chatterji, A., Vijayakumar, R. & Parulekar, A.H. 1988. Growth and morphometric characteristics in the horseshoe crab, Carcinoscorpius rotundicauda (Latreille) from Canning (West Bengal), India. Pakistan J. Sci. Ind. Res. 31: 352-355.
36
Chen, C.P., Yeh, H.Y. & Lin, P.F. 2004. Conservation of the horseshoe crab at Kinmen, Taiwan: strategies and practices. Biodiversity and Conservation 13: 1889-1904. Chen, Y., Lau, C.W., Cheung, S.G., Ke, C.H. & Shin, P.K.S. 2010. Enhanced growth of juvenile Tachypleus tridentatus (Chelicerata: Xiphosura) in the laboratory: a step towards population restocking for conservation of the species. Aquatic Biology 11: 37-46. Christianus, A. & Saad, C.R. 2009. Traditional uses of horseshoe crabs in Malaysia and Thailand. In. Tanacredi, J.T., Botton, M.L. & Smith, D.R. (Eds.), Biology and conservation of horseshoe crabs. New York: Springer Science and Business Media. pp. 616. Davidson, G.W.H., Ng, P.K.L. & Ho, H.C. 2008. The Singapore red data book: threatened plants and animals of Singapore. The Nature Society, Singapore. Evan, C.R. & Lockwood, A.P.M. 1994. Population field studies of the Guinea chick lobster (Panulirus guttatus Latreille) at Bermuda: abundance, catchability, and behavior. J. Shellfish Res. 13:393-415. Gaspar, M.B., Santos, M.N., Vasconcelos, P. & Monteiro, C.C. 2002. Shell morphometric relationship of the most common bivalve species (Mollusca: Bivalvia) of the Algarve coast (southern Portugal). Hydrobiologia 477: 73-80. Google Map, 2015. https://www.google.com.my/maps/@4.0807414,100.6434517,54453m/data=!3m1 !1e3?hl=en [2 March 2015]. Gould, S.J. 1966. Allometry and size in ontogeny and phylogeny. Biological Reviews 41: 587-638.
37
Hajeb, P., Christianus, A., Ismail, A., Shakiba Zadeh, Sh. & Saad, C.R. 2009. Heavy metal concentration in horseshoe crab (Carcinoscorpius rotundicauda and Tachypleus gigas) eggs from Malaysian coastline. In. Tanacredi, J.T., Botton, M.L. & Smith, D.R. (Eds.), Biology and conservation of horseshoe crabs. New York: Springer Science and Business Media. pp. 455-463. Hammer, Ø., Harper, D.A.T. & Ryan, P.D. 2001. PAST: paleontological statistics software package for education and data analysis. Paleontologia Electronica 4(1): 9pp. Henderson, P.A. 2003. Practical method in ecology. United Kingdom: Blackwell Publishing. Hii, Y.S., Law, A.T., Shazili, N.A.M., Abdul Rashid, M.K., Mohd Lokman, H., Yusoff, F.M. & Ibrahim, H.M. 2006. The straits of Malacca: hydrological parameters, biochemical oxygen demand and total suspended solids. Journal of Sustainability Science and Management 1(1): 1-14. Hu, M., Wang, Y., Chen, Y., Cheung, S.G., Shin, P.K.S. & Li, Q. 2009. Summer distribution and abundance of juvenile Chinese horseshoe crabs Tachypleus tridentatus along an intertidal zone in southern China. Aquatic Biology 7: 107-112. Huxley, J.S. & Teissier, G. 1936. Terminology of relative growth. Nature 137:780-781. Ismail, N. & Sarijan, S. 2011. Phylogenetic inference from 18S rRNA gene sequences of horseshoe crabs, Tachypleus gigas between Tanjung Dawai, Kedah & Cherating, Pahang, Peninsular Malaysia. International Journal of Biological, Veterinary, Agricultural and Food Engineering 5:66-69 IUCN (International Union for Conservation of Nature) 2014. Red list of threatened species. King, R.B., Queral-Regil, A. & Stanford, K.M. 2006. Population size and recovery criteria of the threatened Lake Erie watersnake: integrating multiple methods of population estimation. Herpetological Monographs 20: 83-104.
38
Kreamer, G. & Michels, S. 2009. History of horseshoe crab harvest on Delaware Bay. In. Tanacredi, J.T., Botton, M.L. & Smith, D.R. (Eds.), Biology and conservation of horseshoe crabs. New York: Springer Science and Business Media. pp. 299-313. Mishra, J.K. 2009. Horseshoe crabs, their eco-biological status along the north-east coast of India and the necessity for ecological conservation. In: Tanacredi, J.T., Botton, M.L. & Smith, D.R. (Eds.), Biology and conservation of horseshoe crabs. New York: Springer Science and Business Media. pp. 89-96. Mohd Akhir, M.F., Zakaria, N.Z. & Tanggang, F. 2014. Intermonsoon variation of physical characteristics and current circulation along the east coast of Peninsular Malaysia. International Journal of Oceanography 2014: 1-9. Novitsky, T.J. 2009. Biomedical applications of Limulus Amebocyte Lysate. In. Tanacredi, J.T., Botton, M.L. & Smith, D.R. (Eds.), Biology and conservation of horseshoe crabs. New York: Springer Science and Business Media. pp. 315-326. Nurshamimi, I. 2013. Estimating horseshoe crabs (Tachypleus gigas) population size in Tanjung Api Kuantan, Pahang, Peninsular Malaysia. Undergraduate thesis, Bachelor of Applied Science (Conservation and Management of Biodiversity), Faculty of Science and Technology, Universiti Malaysia Terengganu. 48p. Palmer, J.D. 1990. Comparative studies of tidal rhythms. X. A dissection of the persistent activity rhythms of Sesarma. Mar. Behav. Physiol. 17: 177-187. Quinn, G. P. & Keough, M.J. 2002. Experimental design and data analysis for biologists. NY: Cambridge University Press. Royal Ontario Museum. 2008. Oldest horseshoe crab fossil found, 445 million years old. Science
Daily
http://www.sciencedaily.com/releases/2008/02/080207135801.htm. 2014].
39
February. [2
October
Rozihan, M. & Ismail, E. 2011. Genetic structure and haplotype diversity of Tachypleus gigas population along the west coast of Peninsular Malaysia- inferred through mtDNA AT rich region sequence analysis. Biotechnology 10(3): 298-302.
Rozihan, M., Ismail, E., Akbar John, B., Jalal, K.C.A. & Mohd-Adnan, A. 2013. Genetic diversity of horseshoe crab (Tachypleus gigas) in Malaysia revealed using microsatellite markers. Asian Journal of Animal and Veterinary Advances 8(1): 63-72. Sahu, A.C. & Dey, L. 2013. Spawning density and morphometric characteristics of the horseshoe crab Tachypleus gigas (Mϋller) on the Balasore coast of Bay of Bengal, India. Science Vision 13(2): 76-84. Sekiguchi, K. & Shuster, C.N.Jr. 2009. Limits on the global distribution of horseshoe crabs (Limulacea): lessons learned from two lifetimes of observations: Asia and America. In. Tanacredi, J.T., Botton, M.L. & Smith, D.R. (Eds.), Biology and conservation of horseshoe crabs. New York: Springer Science and Business Media. pp. 5-24. Sekiguchi, K., Seshimo, H. & Sugita, H. 1988. Post-embryonic development of the horseshoe crab. Biol. Bull. 174: 337-345. Shin, P.K.S., Li, H.Y. & Cheung, S.G. 2009. Horseshoe crabs in Hong Kong: current population status and human exploitation. In. Tanacredi, J.T., Botton, M.L. & Smith, D.R. (Eds.), Biology and conservation of horseshoe crabs. New York: Springer Science and Business Media. pp. 347-360. Smith, D.R., Millard, M.J. & Eyler, S. 2006. Abundance of adult horseshoe crabs (Limulus polyphemus) in Delaware Bay estimated from a bay-wide markrecapture study. Fish Bulletin 104: 456-464.
40
Srijaya, T.C., Pradeep, P.J., Mithun, S., Hassan, A., Shaharom, F. & Chatterji, A. 2010. A new record on the morphometric variations in the populations of horseshoe crab (Carcinoscorpius rotundicauda Latreille) obtained from two different ecological habitats of Peninsular Malaysia. Our Nature 8:204-211. Tan, A.N., Christianus, A. & Abdul Satar, M.K. 2011. Epibiont infestation on horseshoe crab Tachypleus gigas (Müller) at Pantai Balok in Peninsular Malaysia. Our Nature 9: 9-15 Tan, A.N., Christianus, A., Shakibazadeh, S. & Hajeb, P. 2012. Horseshoe crab, Tachypleus gigas (Müller, 1785) spawning population at Balok beach, Kuantan, Pahang, Malaysia. Pakistan Journal of Biological Sciences 15(13): 610-620. Tanacredi, J.T., Botton, M.L. & Smith, D. (Eds.). 2009. Biology and conservation of horseshoe crabs, New York: Springer Science and Business Media. Thia-Eng, C., Gorre, I.R.L., Adrian Ross, S., Bernad, S.R., Gervacio, B. & Corazon Ebarvia, M. 2000. The Malacca Straits. Marine Pollution Bulletin 41(1): 160-178. Thomas, L. & Krebs, C.J. 1997. A review of statistical power analysis software. Bulletin of the Ecological Society of America 78 (2): 126-138. Vijayakumar, R., Das, S., Chatterji, A. & Parulekar, A.H. 2000. Morphometric characteristics in the horseshoe crab Tachypleus gigas (Arthropoda: Merostomata). Indian Journal of Marine Sciences 29: 333-335. Wallace, B.P., Avens, L., Braun-McNeill, J. & McClellan, C.M. 2009. The diet composition of immature loggerheads: insights on trophic niche, growth rates, and fisheries interactions. Journal of Experimental Marine Biology and Ecology 373: 50-57. Yang, M.C., Chen, C.A., Hsieh, H.L. & Chen, C.P. 2007. Population subdivision of the tri-spine horseshoe crab, Tachypleus tridentatus, in Taiwan Strait. Zoological Science 24: 219-224.
41
Yang, M.C., Chen, C.P., Hsieh, H.L., Huang, H. & Chen, C.A. 2009. Phylogeography, demographic history, and reserves network of horseshoe crab, Tachypleus tridentatus, in the south and east China seaboards. In. Tanacredi, J.T., Botton, M.L. & Smith, D.R. (Eds.), Biology and conservation of horseshoe crabs. New York: Springer Science and Business Media. pp. 163-181. Zaleha, K., Akbar John, B., Erni Atika, H., Kamaruzzaman, B.Y. & Jalal, K.C.A. 2012. Spawning and nesting behaviour of Tachypleus gigas along the East Coast of Peninsular Malaysia. International Journal of Biology 4(2): 102-111. Zar, J.H. 1999. Biostatistical analysis (4th ed). NJ: Prentice Hall Inc., p.663.
42
APPENDICES
Appendix A: Calculations of population size using Chapman‟s modified Peterson method
First sampling occasion (October 2014) 𝑁=
13 + 1 11 + 1 −1 1+1
= 83
𝑉𝑎𝑟 =
83 13 − 1 (11 − 1) 1 + 1 (1 + 2)
= 1660
𝑆. 𝐸. = √1660 = 40.743 𝑃 = 83 + 1660 =1743
Second sampling occasion (October 2014) 𝑁=
12 + 1 11 + 1 −1 0+1
= 155
𝑉𝑎𝑟 =
155 12 − 0 (11 − 0) 0 + 1 (0 + 2)
= 10230
𝑆. 𝐸. = √10230 = 40.743 𝑃 = 83 + 1660 =101.143
44
CURRICULUM VITAE
Name Address
: :
Telephone No. Email Birth date Birth place Nationality Race Sex Religion Education
: : : : : : : : :
Awards
:
Chee Hon Yung C2-12, Taman Setia, Balakong, 43300 Seri Kembangan, Selangor Darul Ehsan 016-2417387
[email protected] 14th March 1992 Teluk Intan Malaysian Chinese Male Christian Bachelor of Applied Science (Conservation & Management of Biodiversity) Universiti Malaysia Terengganu, Terengganu (2012 - 2015) STPM – SMJK Chung Ling (P.Pinang) (2010 – 2012) SPM – SMK Cheras Perdana, Cheras (2008 – 2009) PMR – SMK Cheras Perdana, Cheras (2005 - 2007) UPSR – SRJK (C) Batu Sebelas, Cheras (1999 – 2004) Dean‟s List Award (Semester I 2012/2013) Dean‟s List Award (Semester I 2014/2015)
