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Tri-spine horseshoe crab, Tachypleus tridentatus (L.) in Sabah, Malaysia: the adult body sizes and population estimate
Accepted Manuscript Tri-spine horseshoe crab, Tachypleus tridentatus (L.) in Sabah, Malaysia: the adult body sizes and population Azwarfarid Manca, Faridah Mohamad, Amirrudin Ahmad, Muhd Fawwaz Afham Mohd Sofa, Noraznawati Ismail PII:
S2287-884X(17)30045-6
DOI:
10.1016/j.japb.2017.04.011
Reference:
JAPB 220
To appear in:
Journal of Asia-Pacific Biodiversity
Received Date: 22 September 2016 Revised Date:
11 April 2017
Accepted Date: 26 April 2017
Please cite this article as: Manca A, Mohamad F, Ahmad A, Mohd Sofa MFA, Ismail N, Tri-spine horseshoe crab, Tachypleus tridentatus (L.) in Sabah, Malaysia: the adult body sizes and population, Journal of Asia-Pacific Biodiversity (2017), doi: 10.1016/j.japb.2017.04.011. This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
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Tri-spine horseshoe crab, Tachypleus tridentatus (L.) in Sabah, Malaysia: the adult body sizes and population
Mohd Sofaa,b, and Noraznawati Ismaila,c
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Corresponding author: [email protected]
Horseshoe Crab Research Group (HCRG)
b
School of Marine and Environmental Sciences
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a
c
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Azwarfarid Mancaa,b, Faridah Mohamada,b,*, Amirrudin Ahmada,b, Muhd Fawwaz Afham
Institute of Marine Biotechnology, Universiti Malaysia Terengganu, 21030 Kuala
ABSTRACT
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Terengganu, Terengganu, Malaysia.
Dwindling number of the tri-spine horseshoe crab, T. tridentatus has been reported globally.
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Similar case is also seen in Malaysia, specifically in Sabah where locals claim that the animal
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is less seen in the present compared to previous years. However, there is no scientific data on its population status. Capture-mark-recapture (CMR) method were carried out from October 2014 through September 2015 to estimate the abundance of adult T. tridentatus in Tawau, Sabah. Samples were also weighed and examined for their body parameters (i.e. prosomal width, carapace length, telson length, total length, intraocular distance). The estimated population sizes of T. tridentatus ranged from 182-1,095 with 95% confident limits of 5642,942 individuals (Schnabel formula). Multivariate Discriminant Hotelling T2 test verifies the sexual size dimorphism among the adult T. tridentatus with 97.7% separation among
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ACCEPTED MANUSCRIPT sexes (Hotelling T2=778.49, F=152.85, p<0.001) with female being larger and heavier than the male individuals. The number estimated from the study is the first being reported for T. tridentatus in Malaysia, particularly in Sabah. Even though this number may slightly overestimate the actual population size in the area owing to the low number of individuals
Keywords:
Tachypleus
tridentatus,
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recaptured, for now it could serve as baseline data for horseshoe crab management purpose.
capture-mark-recapture,
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horseshoe crab, Sabah, Malaysia.
population,
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abundance,
ACCEPTED MANUSCRIPT Introduction There are four horseshoe crabs in the world nowadays. These horseshoe crabs distributed widely with one species confined to the Atlantic Ocean namely the American horseshoe crab Limulus polyphemus that distributed widely within the geographic ranges from 21° to 44° N
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and 68° to 90° W covers the area of Maine in the North of America (Sekiguchi and Shuster 2009; Shuster 2015), down to Yucatan in the Gulf of Mexico (Zaldivar-Rae et al 2009) with the highest population recorded in Delaware Bay (Sekiguchi and Shuster 2009; Walls et al
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2002). The other three horseshoe crab species (known as the Asian horseshoe crabs) namely coastal horseshoe crab Tachypleus gigas, tri-spine horseshoe crab T. tridentatus and
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mangrove horseshoe crab Carcinoscorpius rotundicauda distributed in Indo-pacific Ocean that range from 6° S to 31° N and between 90° to 118° E (Sekiguchi and Shuster 2009) covering the Bay of Bengal in India to Philippines and from South-West Japan down to China, Thailand, Malaysia and Indonesia in the south (Carmichael and Brush 2012; Chatterji
waters.
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1994). Recent recovery by Yang and Ko (2015) also reported T. tridentatus in the Korean
Tachypleus tridentatus is one of the three Asian horseshoe crab species available in
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Malaysia, with a distribution limited to East Malaysia only. The horseshoe crabs were
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utilized by locals mainly for the human consumption as delicacies, especially the egg-bearing female (Christianus and Saad 2009; Faridah et al 2015) that typically sell for a price of MYR20 (~5 USD) per individual in local wet market. The horseshoe crabs were also used in traditional remedies for treating joint pains and fever (Basudev et al 2013; Mishra 2009; Pradeep and Srijaya 2010). In certain area of Sabah, locals used to hang T. tridentatus carcasses in their homes for protection from bad spirit apart from ornamental purpose. Declining number of T. tridentatus population was reported globally specifically in China and Japan. Rapid development to produce TAL kit has been reported in China (Gauvry
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ACCEPTED MANUSCRIPT 2015), where T. tridentatus were previously harvested on a large scale for their blood for TAL production. Recently, it is reported that the adult T. tridentatus were rarely seen compared to the past 30-40 years (Berkson et al 2009; Shin et al 2009). As a result, intensive research on monitoring the population of the juvenile T tridentatus has been conducted in
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China especially in Hong Kong and Taiwan with the aim to address the issue for restoring the horseshoe crab population in the areas (Chen et al 2004; Chen et al 2010; Hu et al 2009; Kwan et al 2016; Morton and Lee 2011).
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Similar patterns have been reported in Japan where rapid development of land reclamation caused a significant decline of T. tridentatus population number (Seino et al
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2003; Tsuchiya 2009). Even with such great management for the conservation purpose, the population of T. tridentatus in Japan remained low. Five years spawning population surveys conducted by Wada et al (2010) in Tsuyazaki Coast in Fukuoka, Japan reported a consistent reduction of spawning pairs from 139 recorded in 2002 to only 40 pairs in 2008 and is
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expected to continuously decrease in the coming years.
Unfortunately, there is a lack of literature on T. tridentatus population in Malaysia, compared to both T. gigas and C. rotundicauda in Peninsular Malaysia (e.g. Faridah et al
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2015; Ismail and Sarijan 2011; Manca et al 2016; Nelson et al 2015; Srijaya et al 2010; Tan
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et al 2012; Zaleha et al 2012). In fact, no specific research has been conducted to update the current population status of T. tridentatus in Sabah. Local anecdotal reports of the decreasing number of T. tridentatus have urged the need to obtain a scientific data on T. tridentatus abundance. As T. tridentatus is listed as data deficient in IUCN red list (IUCN 2015), any information on this animal will be valuable to update the information on this animal. This study was carried out to address the research gap as mentioned above with the aims to (i) estimate the population size of adult T. tridentatus in Tawau waters, (ii) determine the
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ACCEPTED MANUSCRIPT sex ratio of the offshore adult T. tridentatus, and (iii) evaluate the morphometric variation among sexes.
Materials and Methods
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Sampling site
This study was carried out in Tawau that located in the south-east region of Sabah in the
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Malaysian Borneo, facing the Celebes Sea (Figure 1). The fishermen village is situated on the edge of the mainland with most of the ‘amphibian’ houses are built on poles along the
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intertidal coastline. This densely populated area is inhabited by approximately 3,000 residents with most of the villagers are fishermen, is subject to heavy fishing activities with active aqua farming ponds in the vicinity. The presence of fish landing jetties confirms the importance of this area in the local fisheries industry. The land areas are dominated by oil palm trees, with
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patches of common dwarf tropical mangrove plants such as Rhizophora spp. and Bruguiera spp., whereas bigger mangrove apples (Sonneratia spp.) trees dominated the seawards area. The study was carried out in five months during a sampling duration from October 2014
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through September 2015. This site was selected based on the availability of T. tridentatus as
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confirmed from the site visit conducted in 2014.
Samples collection
Samples of adult T. tridentatus were collected using gill-net that deployed into the sea down to 5 m depth, approximately 1-3 km from the shore. The net (mesh size 11.4 cm, 1.0 m height × 400 m length; a type of net commonly used by fishermen to capture crabs in the study area) were deployed with at least 24 hours soaking time. After 24 hours, the net was hauled and all tangled horseshoe crabs were removed from the net and placed in the boat for
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ACCEPTED MANUSCRIPT marking protocol. Captured horseshoe crabs were recorded, examined for their sex based on the presence of pedipalps (clasper) on the first and second pairs of walking leg, measured for their body parameters and weighed using a digital balance (model DJC31G-30) before
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released into the water at the capture point.
Estimation population size: capture-mark-recapture (CMR) methods.
In general, 15 CMR samplings were conducted within the five months sampling period.
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The horseshoe crab samples were captured using the method mentioned in Section 2.2. All tangled horseshoe crabs were marked with white button tag that bears a unique individual
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number on the left side of the prosoma (latero-posterior point) before released at the capture point (see Faridah et al 2015; Mattei and Beekey 2008). A total of three CMR samplings were carried out per month with at least 48 hours gap between each samplings. These time gap is to allow the marked individuals to recover and mingle with the unmarked population
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before the next sampling.
The estimation of T. tridentatus abundance in Tawau waters was calculated using
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follows:
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Schnabel formula with an assumption of closed population (Krebs 1999). The formula is as
′
=
∑ ∑ 1
′
+ 1 =
1 = ′
6
∑
1 ′
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Where, N’ = the estimated population size, Ct = the total number of individuals captured in sample t,
Rt = the recaptured individuals during the sample t.
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Measurement of body parameters
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Mt = the cumulative number of marked individuals before the t sample, and
All netted T. tridentatus were examined for their sex and measured for their body
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parameters using a measuring tape to the nearest 0.1 cm. Each individual of T. tridentatus was measured for five body parameters which were prosomal width (PW); the widest part of the prosoma measured across the ventral side, carapace length (CL); the length from the tip of prosoma to the anus, telson length (TEL); the length of rigid tail from the anus to the end of
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tail projection, total length (TL); the total length from the tip of prosoma to the end of tail, and intraocular distance (IO); distance between the two compound eyes as depicted in Figure 2. All measured individuals had a full complement of body forms with no visible body
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deformations. Those horseshoe crabs with damaged, injured or regenerated body partss were
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excluded from analysis and released into the water immediately upon captures.
Statistical analysis
Morphometric data of from the collected T. tridentatus were pooled according to sex and sampling months. The variation of sex ratio among T. tridentatus was tested using Chi2 test, whereas Independent-samples t-test was run to determine the significant difference of mean for each body parameters between male and female individuals. Multivariate Discriminant Hotelling T2 test was run to verify the discreteness between sexes of T. tridentatus in the
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ACCEPTED MANUSCRIPT study site. Paleontological Statistics (PAST) software version 2.17c (Hammer et al 2001) and Microsoft Office ExcelTM 2007 with Analysis Toolpak were used to run the statistical analyses with significance accepted at p<0.05.
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Results and discussion Abundance of T. tridentatus in Tawau waters
A total of 271 catches from 267 individuals T. tridentatus were recorded throughout the
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samplings. The number of captured individuals varied among the months with highest recorded in October with 113 individuals representing 41.7% from the total catch. This
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followed by February and September with 50 (18.5%) and 46 (17.0%) individuals respectively. Lowest individuals captured were recorded in April with 29 (10.7%) individuals.
The CMR sampling recorded very low recaptured individuals with only four individuals
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(1.5% recapture rates) from the total catch. Of these, two individuals were recaptured within the same sampling month; i.e. one female (tag ID 1329) that marked on second sampling day was recaptured on the third sampling day in October 2014, whereas another female (tag ID
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1487) was recaptured on the second day CMR in September 2015. Two more individuals
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were recaptured later on different sampling months (Table 1). One male (tag ID 1302) marked during October 2014 was recaptured four months later in February 2015, and sampling conducted in April recorded another recaptured male (tag ID 1434) that was marked in February. Similar pattern of low recaptured individuals were reported in Faridah et al (2015) study as only six total recaptured individuals were reported in their CMR study on T. gigas population in Pahang waters. A 17-year tagging study by Swan (2005) reported only about 7% recovery of the marked L. polyphemus. Such low recaptured individuals might be
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ACCEPTED MANUSCRIPT due to high mobility of horseshoe crabs under the deep sea with larger home range ranging from 26.9-98.6 ha as estimated in L. polyphemus (Moore and Perrin 2007). The population size estimates ranged from 182-1,095 (95% confidence limits of 5642,942) individuals (Table 2). This is the first report on the abundance of T. tridentatus in
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Sabah waters. Since there is no comparable data from previous study, it cannot be assured whether these numbers represent the growing population of T. tridentatus in the areas or showing a decrease in number over the past decades as claimed by locals. However, these
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numbers indicate very low population size as compared to the estimated number of L. polyphemus in the USA. For instance, Smith et al (2006) estimate that L. polyphemus
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population in Delaware Bay was 20 million (90% confidence interval of 13-28 million) individuals. Moreover, Engel (2005) reported that during their 2004 survey, there were 259,000 and 63,000 L. polyphemus in both Slaughter and Bower beaches respectively. These estimated population numbers in the USA were based on the spawning population that
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congregates onshore to nest during the spawning season, whereas the present study reported the offshore population which is not in the spawning mode. It is suspected that the spawning population T. tridentatus might be even lower based on the evidence from previous study in
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all Asian horseshoe crab species (e.g. Behera et al 2015; Botton et al 1996; Cartwright-Taylor
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et al 2011; Manca et al 2016; Mattei et al 2010; Seino et al 2003; Shin et al 2009; Wada et al 2010).
Several studies on the offshore population of horseshoe crabs as conducted by Hata and Berkson (2003) in USA reported higher population size with an average of 6.8-11.4 million individuals within 22.2 km offshore. The current findings only represent approximately 0.01% from the offshore L. polyphemus in Hata and Berkson’s study. Similarly, there is higher number of the offshore T. gigas in Pahang on the east coast of Peninsular Malaysia with 7,140 and 9,900 individuals in Chendor and Cherating waters respectively (Faridah et al
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resulted from higher recapture individuals. Owing to the extremely low recapture rate, in addition to an extended sampling duration and repeated monitoring, it is even more important to obtain higher
recaptures in each CMR sampling events. Therefore, a larger sampling
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effort such as deploying more gill-nets is recommended if such sampling is to be repeated
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annually for monitoring purpose.
Sex ratio of T. tridentatus population in Tawau
The overall sex ratio of the offshore T. tridentatus were skewed to males with 2.08:1 male to female ratio. Only April shows the reverse (Table 1). Similar findings were reported
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for the offshore T. gigas in Pahang, Malaysia with higher male-bias of 14:1 (Faridah et al 2015). Brockmann et al (2015) speculated that the male-skewed population in horseshoe crab populations occurs in the regions where females were preferable to be harvested. This agrees
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with the previous report of commercial harvest of egg-bearing females T. gigas to be
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consumed as local dishes or exported to fulfill market demands (Christianus and Saad 2009; Faridah et al 2015; Ismail et al 2012; Robert et al 2014). In contrast, the male-biased sex ratio somehow is common for L. polyphemus population especially the spawning population on breeding beaches. It was reported that male numbers were consistently higher than the female (Brockmann and Johnson 2011; Carmichael et al 2003; James-Pirri et al 2005; Rudloe 1980; Shuster and Botton 1985; Smith et al 2006, 2010) with up to 15 males per female (Loveland and Botton 1992; Engel 2005). Extreme male-bias in spawning population of L. polyphemus with the presence of spawning group (Brockmann
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ACCEPTED MANUSCRIPT and Johnson 2011; Brockmann et al 2010) suggested higher population size in the area. This contradicts with the spawning Asian horseshoe crabs species that demonstrate 1:1 sex ratio or very little male-biased ratio (Botton et al 1996; Cartwright-Taylor 2015; Manca et al 2016; Mattei et al 2010; Tan et al 2012; Zaleha et al 2012). Botton and Loveland (1992) and Botton
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et al (1996) mentioned that lack of male-bias in the Asian horseshoe crab spawning population was likely due to low population number that led to no mating competition among the male Asian horseshoe crabs. This suggests that the population size estimated in the
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current study may represent the non-spawning population as higher male-bias recorded which
Measurement of body parameters
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is unlikely to be the case for the spawning Asian horseshoe crabs.
Table 3 shows the descriptive statistic for both male and female T. tridentatus collected in Tawau waters in Sabah. All individuals were adult individuals with PW size ranged from
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20.0-29.8 (mean±SD; 25.7±1.6) cm and weight of 600-1700 g for males whereas, 24.2-36.2 (31.2±2.3) cm and weight of 1400-4000 g for females. Sekiguchi et al (1988) throughout their 10-year rearing of T. tridentatus in the lab concluded that T. tridentatus reach the adult
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stage with mean PW (±SD) of 24.4±1.9 cm and 27.8±1.7 cm for male and female
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respectively. However, Wada et al (2010) reported smaller size of mature individuals collected from wild spawning pairs in Tsuyazaki coast, Fukuoka, Japan with a mean of 22.6 cm for male and 27.6 cm for female. This suggests that horseshoe crabs in the wild may reach maturity at a smaller size as compared to the reared individuals which might be due to environmental stressor probably by insufficient food resources (Blankenhorn 2000). It was also reported that the horseshoe crabs may reach maturity with variable size based on the evidence of discrete PW sizes among the horseshoe crab populations from different localities (Sekiguchi and Shuster 2009).
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ACCEPTED MANUSCRIPT It was confirmed that female T. tridentatus were significantly larger in PW (t=-20.56, p<0.001), CL (t=-24.45, p<0.001), TEL (t=-10.67, p<0.001), TL (t=-17.96, p<0.001), and IO (t=-26.12, p<0.001) as shown in Table 3. This proved that females T. tridentatus do reach maturity with an additional instar stage than the males as proposed by Sekiguchi et al (1988).
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Female T. tridentatus reach maturity after 16 times molting in the 14th year, one additional instar stage from male individuals that mature with only 15 times in the 13th year. Carmichael et al (2015) recently speculated that female horseshoe crabs may possibly molt at
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least once after mating (i.e. post-reproductive molting) before reaching their terminal molt. Based on the presumed size from Sekiguchi et al (1988), both male and female T. tridentatus
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collected in Sabah were on their 16th and 17th instar stages respectively, confirming that collected individuals were adult individuals with different instar stages, thus explained the significantly larger size in female body parameters compared to male T. tridentatus. The PW in females collected were consistently larger than the males throughout the sampling months
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(Figure 3). This SSD is also shown by mangrove horseshoe crabs C. rotundicauda in Singapore (Cartwright-Taylor et al 2009).
The body parameters in male and female T. tridentatus were significantly distinct with
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97.7% separation between the sexes (Multivariate Discriminant Hotelling T2=778.49,
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F=152.85, p<0.001), suggesting that it is appropriate for determination of sexual size dimorphism in T. tridentatus population in Sabah waters. Cartwright-Taylor et al (2009) and Loveland and Botton (1992) mentioned that SSD in horseshoe crabs was demonstrated by female being larger than male even though there is a slight overlapping of size between the largest male and the smallest female. This might be the result of their mating system where females use their large body to tow the male that clings on their opisthosomal spines (i.e. amplexus) during the spawning seasons. It was reported that the amplexus pair may remain more than a week (Botton et al 1996; Robert et al 2014). Suggs et al (2002) speculated that
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ACCEPTED MANUSCRIPT some size-based mate selection may occur among the spawning horseshoe crabs in which the males tended to prefer larger-size females to perform amplexus. This might be due to the fact that larger females may possibly be more productive and bear more eggs in their body.
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Conclusion
The adults T. tridentatus exhibit sexual size dimorphisms with female being significantly larger than the males. Their population in Sabah waters is estimated to range from 182-1,095
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(95% confidence limits of 56-42,942) individuals with male-biased sex ratio of 2.08:1. This is the first report on the population size of adult T. tridentatus in Sabah waters, providing a
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baseline data of T. tridentatus population in Malaysia. The approach used in this study could be applied annually in the monitoring and management plans for the species in Sabah.
Conflict of interest
Acknowledgments
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The authors declare that there is no conflict of interest.
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This study was funded by Sabah Biodiversity Center, SaBC [grant number: TJ 66917].
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The authors would like to thank Universiti Malaysia Terengganu, UMT for the facilities provided, and the villagers/fishermen in Tawau for their help and inputs during the sampling period.
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ACCEPTED MANUSCRIPT References
Askey PJ, Post JR, Parkinson EA, et al. 2007. Estimation of gillnet efficiency and selectivity
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across multiple sampling units: a hierarchical Bayesian analysis using mark-recapture data. Fisheries Research 83:162-174.
Basudev T, Sivakumar K, Sajan J, et al. 2013. Assessment of the population status and threats
SC
to the horseshoe crabs along the northern east coast of India. In: Venkataraman K, Sivaperuman C, Raghunathan C, editors. Ecology and conservation of tropical marine
M AN U
faunal communities. New York: Springer. pp 137-146.
Behera S, Tripathy B, Sivakumar K, et al. 2015. Distribution and abundance of two sympatric species of horseshoe crabs along the Odisha Coast, India. In: Carmichael RH, Botton ML, Shin PKS, et al, editors. Changing global perspectives on horseshoe crab biology,
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conservation and management. New York: Springer. pp 181-191. Berkson J, Chen CP, Mishra J, et al. 2009. A discussion of horseshoe crab management in
EP
five countries: Taiwan, India, China, United States, and Mexico. In: Tanacredi JT, Botton ML, Smith DR, editors. Biology and conservation of horseshoe crabs. New York,
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Springer. pp 465-475.
Blanckenhorn WU. 2000. The evolution of body size: what keeps organism small? The Quarterly Review of Biology 75(4):385-407. Botton ML, Shuster CN Jr, Sekiguchi K, et al. 1996. Amplexus and mating behavior in the Japanese horseshoe crab, Tachypleus tridentatus. Zoological Science 13:151-159. Brockmann HJ, Johnson SL, Smith MD, et al. 2015. Mating tactics of the American horseshoe crab (Limulus polyphemus). In: Carmichael RH, Botton ML, Shin PKS, et al,
14
ACCEPTED MANUSCRIPT editors. Changing global perspectives on horseshoe crab biology, conservation and management. New York: Springer. pp 321-352. Brockmann HJ, Johnson SL. 2011. A long-term study of spawning activity in a Florida Coast
1067.
RI PT
population of horseshoe crabs (Limulus polyphemus). Estuaries and Coasts 34:1049-
Brockmann HJ, Nguyen C, Potts W. 2010. Paternity in horseshoe crabs when spawning in
SC
multiple-male groups. Animal Behaviour 60:837-849.
Carmichael RH, Brush E. 2012. Three decades of horseshoe crabs rearing: a review of
M AN U
conditions for captive growth and survival. Reviews in Aquaculture 4:32-43. Carmichael RH, Hieb EE, Gauvry G, et al. 2015. Examination of large exuviae with mating scars: do female American horseshoe crabs, Limulus polyphemus, molt after sexual maturity? In: Carmichael RH, Botton ML, Shin PKS, et al, editors. Changing global
Springer. pp 353-368.
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perspectives on horseshoe crab biology, conservation and management. New York:
EP
Carmichael RH, Rutecki D, Valiela I. 2003. Abundance and population structure of the Atlantic horseshoe crab Limulus polyphemus in Pleasant Bay, Cape Cod. Marine
AC C
Ecology Progress Series 246:225-239. Cartwright-Taylor L, Bing YV, Chi HC, et al. 2011. Distribution and abundance of horseshoe crabs Tachypleus gigas and Carcinoscorpius rotundicauda around the main island of Singapore. Aquatic Biology 13:127-136. Cartwright-Taylor L, Lee J, Hsu CC. 2009. Population structure and breeding pattern of the mangrove horseshoe crab Carcinoscorpius rotundicauda in Singapore. Aquatic Biology 8:61-69.
15
ACCEPTED MANUSCRIPT Cartwright-Taylor L. 2015. Studies of horseshoe crabs around Singapore. In: Carmichael RH, Botton ML, Shin PKS, et al, editors. Changing global perspectives on horseshoe crab biology, conservation and management. New York: Springer. pp 193-211.
RI PT
Chatterji A. 1994. The horseshoe crab – a living fossil. Orissa: Project Swarajya Publication. Chen CP, Yeh HY, Lin PF. 2004. Conservation of the horseshoe crab at Kinmen, Taiwan: strategies and practices. Biodiversity and Conservation 13:1889-1904.
SC
Chen Y, Lau CW. Cheung SG, et al. 2010. Enhanced growth of juvenile Tachypleus tridentatus (Chelicerata: Xiphosura) in the laboratory: a step towards population
M AN U
restocking for conservation of the species. Aquatic Biology 11:37-46.
Christianus A, Saad CR. 2009. Traditional uses of horseshoe crabs in Malaysia and Thailand. In: Tanacredi JT, Botton ML, Smith DR, editors. Biology and conservation of horseshoe
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crabs. New York: Springer. pp 616.
Engel E. 2005. Trailing the ancient mariner. The Chesapeake’s Independent Newspaper Online 13(25):1-5.
EP
Faridah M, Ismail N, Ahmad BA, et al. 2015. The population size and movement of coastal
AC C
horseshoe crab, Tachypleus gigas (Muller) on the east coast of Peninsular Malaysia. In: Carmichael RH, Botton ML, Shin, PKS, et al, editors. Changing global perspectives on horseshoe crab biology, conservation and management. New York: Springer. pp 213228.
Gauvry G. 2015. Current horseshoe crab harvesting practices cannot support global demand for TAL/LAL: the pharmaceutical and medical devices industries’ role in the sustainability of horseshoe crabs. In: Carmichael RH, Botton ML, Shin PKS, et al,
16
ACCEPTED MANUSCRIPT editors. Changing global perspectives on horseshoe crab biology, conservation and management. New York: Springer. pp 475-500. Hammer Ø, Harper DAT, Ryan PD. 2001. PAST: Paleontological statistics software package
RI PT
for education and data analysis. Palaeontologia Electronica 4:9. Hata D, Berkson J. 2003. Abundance of horseshoe crabs (Limulus polyphemus) in the Delaware Bay area. Fishery Bulletin 101(4):933-938.
SC
Hu M, Wang Y, Chen Y, et al. 2009. Summer distribution and abundance of juvenile Chinese horseshoe crabs Tachypleus tridentatus along an intertidal zone in southern China.
M AN U
Aquatic Biology 7:107-112.
Ismail N, Jolly JJ, Dzulkiply SK, et al. 2012. Allometric variations of horseshoe crab (Tachypleus gigas) populations collected from Chendor and Cherating, Pahang,
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Peninsular Malaysia. Journal of Sustainability Science and Management 7(2):164-169. Ismail N, Sarijan S. 2011. Phylogenetic inference from 18S rRNA gene sequences of horseshoe crabs, Tachypleus gigas between Tanjung Dawai, Kedah and Cherating,
EP
Pahang, Peninsular Malaysia. International Journal of Biological, Agricultural and Food
AC C
Engineering 5(8):66-69. IUCN
(International
Union
for
Conservation
of
Nature).
2015.
Available
at:
http://www.iucnredlist.org/details/21309/0. [Date accessed: 15 August 2016]. James-Pirri MJ, Tuxbury K, Marino S, et al. 2005. Spawning densities, egg densities, size structure, and movement patterns of spawning horseshoe crabs, Limulus polyphemus, within four coastal embayments on Cape Cod, Massachusetts. Estuaries 29(2):296-313.
17
ACCEPTED MANUSCRIPT Krebs CJ. 1999. Ecological methodology, 2nd ed. London: Addison-Welsey Educational Publishers Inc. Kwan BKY, Hsieh HL, Cheung SG, et al. 2016. Present population and habitat status of threatened
Asian
horseshoe
crabs
Tachypleus
tridentatus
and
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potentially
Carcinoscorpius rotundicauda in Hong Kong: a proposal for marine protected areas. Biodiversity and Conservation 25(4):673-692.
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Loveland RE, Botton ML. 1992. Size dimorphism and the mating system in horseshoe crabs, Limulus polyphemus L. Animal Behaviour 44(5):907-916.
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Manca A, Mohamad F, Nelson BR, et al. 2016. Trailing the spawning horseshoe crab Tachypleus gigas (Müller, 1785) at designated natal beaches on the East Coast of Peninsular Malaysia. Cell and Developmental Biology 5(171):1-6. Mattei JH, Beekey MA, Rudman A, et al. 2010. Reproductive behavior in horseshoe crabs:
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does density matter? Current Zoology 56(5):634-642. Mattei JH, Beekey MA. 2008. The horseshoe crab conundrum: can we harvest and conserve?
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Wrack Lines 8(1):2-7.
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Mishra JK. 2009. Horseshoe crabs, their eco-biological status along the Northeast Coast of India and the necessity for ecological conservation. In: Tanacredi JT, Botton ML, Smith DR, editors. Biology and conservation of horseshoe crabs. New York: Springer. pp 8996.
Moore S, Perrin S. 2007. Seasonal movement and resource-use patterns of resident horseshoe crabs (Limulus polyphemus) populations in a Maine, USA estuary. Estuaries and Coasts 30(6):1016-1026.
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ACCEPTED MANUSCRIPT Morton B, Lee CN. 2011. Spatial and temporal distribution of juvenile horseshoe crabs (Arthropoda: Chelicerata) approaching extirpation along the northwestern shoreline of the new territories of Hong Kong SAR, China. Journal of Natural History 45(3-4):227-
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251. Nelson BR, Satyanarayana B, Zhong JMH, et al. 2015. Episodic human activities and seasonal impacts on the Tachypleus gigas (Müller, 1785) population at Tanjung Selangor
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in Peninsular Malaysia. Estuarine, Coastal and Shelf Science 164:313-323.
Pradeep PJ, Srijaya TC. 2010. A primitive ancient wonder – horseshoe crab. Science India: 4-
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11.
Robert R, Muhammad Ali SH, Amelia-Ng PF. 2014. Demographics of horseshoe crab populations in Kota Kinabalu, Sabah, Malaysia with emphasis on Carcinoscorpius rotundicauda and some aspects of its mating behaviour. Journal of Tropical Agricultural
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Science 37(3):375-388.
Rudloe A. 1980. The breeding behavior and patterns of movement of horseshoe crabs,
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Limulus polyphemus, in the vicinity of breeding beaches in Apalachee Bay, Florida. Estuaries 3(3):177-183.
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Seino S, Uda T, Tsuchiya Y, et al. 2003. Conservation history of horseshoe crab Tachypleus tridentatus and its spawning ground, a designated natural monument in Kasaoka Bay in Okayama prefecture. Asian and Pacific Coasts: 1-14. Sekiguchi K, Seshimo H, Sugita, H. 1988. Post-embryonic development of the horseshoe crab. Biological Bulletin 174:337-345. Sekiguchi K, Shuster Jr CN. 2009. Limits on the global distribution of horseshoe crab (Limulacea): lessons learned from two lifetimes of observations: Asia and America. In:
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ACCEPTED MANUSCRIPT Tanacredi JT, Botton ML, Smith DR, editors. Biology and conservation of horseshoe crabs. New York: Springer. pp 5-24. Shin PKS, Li HY, Cheung SG. 2009. Horseshoe crabs in Hong Kong: current population
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status and human exploitation. In: Tanacredi JT, Botton ML, Smith DR, editors. Biology and conservation of horseshoe crabs. New York, Springer. pp 347-360.
Shuster CN Jr, Botton ML. 1985. A contribution to the population biology of horseshoe
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crabs, Limulus polyphemus (L.), in Delaware Bay. Estuaries 8(4):363-372.
Shuster CN Jr. 2015. The Delaware Bay area, U.S.A.: a unique habitat of the American
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horseshoe crab, Limulus polyphemus. In: Carmichael RH, Botton ML, Shin PKS, Cheung SG, editors. Changing global perspectives on horseshoe crab biology, conservation and management. New York: Springer. pp 15-40.
Smith DR, Brousseau LJ, Mandt MT, et al. 2010. Age and sex specific timing, frequency, and
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spatial distribution of horseshoe crab spawning in Delaware Bay: Insights from a largescale radio telemetry array. Current Zoology 56(5):563-574.
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Smith DR, Millard MJ, Eyler S. 2006. Abundance of adult horseshoe crabs (Limulus polyphemus) in Delaware Bay estimated from a bay-wide mark-recapture study. Fishery
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Bulletin 104:456-464.
Srijaya TC, Pradeep PJ, Mithun S, et al. 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. Suggs DN, Carmichael RH, Grady SP, et al. 2002. Effects of individual size on pairing in horseshoe crabs. Biological Bulletin 203:225-227.
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ACCEPTED MANUSCRIPT Tan AN, Christianus A, Shakibazadeh S, et al. 2012. Horseshoe crab, Tachypleus gigas (Müller, 1785) spawning population at Balok beach, Kuantan, Pahang, Malaysia. Pakistan Journal of Biological Sciences 15(13):610-620.
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Tsuchiya K. 2009. The history of horseshoe crab research and conservation in Japan. In: Tanacredi JT, Botton ML, Smith DR, editors. Biology and conservation of horseshoe crabs. New York: Springer. pp 559-570.
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Wada T, Itaya S, Shuuno M. 2010. Spawning sites and annual variability of the number of reproductive visiting pairs of the horseshoe crab Tachypleus tridentatus along the
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Tsuyazaki Coast in Fukuoka, Japan. Japanese Journal of Conservation Ecology 15:163171.
Walls EA, Berkson J, Smith SA. 2002. The horseshoe crab, Limulus polyphemus: 200 million years of existence, 100 years of study. Reviews in Fisheries Science 10:39-73.
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Yang KC, Ko SH. 2015. First record of tri-spine horseshoe crab, Tachypleus tridentatus (Merostomata: Xiphosurida: Limulidae) from Korean waters. Animal Systematics,
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Evolution and Diversity 31:42-45.
Zaldívar-Rae J, Sapién-Silva E, Rosales-Raya M, et al. 2009. American horseshoe crabs,
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Limulus polyphemus, in Mexico: open possibilities. In: Tanacredi JT, Botton ML, Smith DR, editors. Biology and conservation of horseshoe crabs. New York: Springer. pp 97114.
Zaleha K, Akbar John B, Erni Atika H, et al. 2012. Spawning and nesting behaviour of Tachypleus gigas along the East Coast of Peninsular Malaysia. International Journal of Biology 4(2):102-111.
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ACCEPTED MANUSCRIPT Figure captions Figure 1.
Map showing the location of sampling site as indicated by an arrow. Inset shows both Peninsular and East Malaysia with Sabah state highlighted in
Figure 2.
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green.
The measurement of T. tridentatus morphological parameters. (PW, prosomal width; CL, carapace length; TEL, telson length; TL, total length; and IO,
Figure 3.
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for each morphological measurements.
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intraocular distance). Image of male T. tridentatus is shown with an example
The variation of prosomal width of male and female T. tridentatus in different sampling months in Tawau, Sabah. The prosomal width in females were consistently larger than the males (two sample t-test; p<0.001). Box shows
Descriptive summary of pooled capture-mark-recapture (CMR) data and sex
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Table 1
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median and quartiles, whiskers are 95% confidence interval.
ratios of T. tridentatus population in Tawau, Sabah. Few mortalities recorded
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in April, July and September 2015 led to the reduction of marked and released individuals.
Table 2
The population size of T. tridentatus estimated from Schnabel formula. Some parameters cannot be computed for February, April, and July as there were no recaptured individuals recorded during the sampling.
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The mean±SD (range) of body parameters (cm) for male and female T.
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tridentatus collected from Tawau waters.
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ACCEPTED MANUSCRIPT List of Tables
Table 1
Descriptive summary of pooled capture-mark-recapture (CMR) data and sex ratios of T. tridentatus population in Tawau, Sabah. Few mortalities recorded
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in April, July and September 2015 led to the reduction of marked and released individuals.
The population size of T. tridentatus estimated from Schnabel formula. Some
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Table 2
parameters cannot be computed for February, April, and July as there were no
Table 3.
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recaptured individuals recorded during the sampling.
The mean±SD (range) of body parameters (cm) for male and female T.
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tridentatus collected from Tawau waters.
Table 1 Month
Total Caughta
Recaptured Total marked Sex Ratio Individuals and Releasedb (Male:Female)
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Year
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χ2
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Male Female 2014 October 80 33 1c 112 2.42:1 s d 2015 February 42 8 1 49 5.25:1 s April 13 16 1d 25 0.81:1 n/s July 19 14 0 29 1.36:1 n/s 17 1c 40 1.71:1 n/s September 29 Total 183 88 4 255 2.08:1 s a = total individuals captured from pooled CMR session according to months, b = total individuals that marked and released alive, c = individuals recaptured within the same sampling month, d = individuals recaptured on different sampling month, s = significant, n/s = not significant.
Table 2
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Sampling Months Oct 14 Feb 15 Apr 15 Jul 15 Pop. Size (N) 1,095 669 182 320 Variance 2.085 × 10-7 n/a n/a n/a -4 n/a n/a n/a Standard Error 4.566 × 10 Lower 95% CL 412 204 56 98 Upper 95% CL 42,942 n/a n/a n/a N = population size estimate, CL = confidence limits, n/a = not available.
Sep 15 304 2.705 × 10-6 1.645 × 10-3 115 11,922
Table 3
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Body Parameters (cm) PW CL TEL TL a a a Male 25.7±1.6 25.1±1.7 28.6±3.5 53.8±4.6a (n=154) (20.0-29.8) (20.0-32.6) (20.0-38.0) (41.0-65.7) b b b Female 31.2±2.3 32.1±2.4 34.6±4.5 66.7±5.6b (n=67) (24.2-36.2) (26.5-39.5) (17.0-42.7) (47.5-79.5) PW=prosomal width, CL=carapace length, TEL=telson length, TL=total IO=intraocular distance. a and b indicate significant difference at p<0.001 (Independent-samples t-test)
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IO 13.8±0.9a (11.0-16.1) 17.7±1.3b (14.0-21.2) length, and
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S2287-884X(17)30045-6
DOI:
10.1016/j.japb.2017.04.011
Reference:
JAPB 220
To appear in:
Journal of Asia-Pacific Biodiversity
Received Date: 22 September 2016 Revised Date:
11 April 2017
Accepted Date: 26 April 2017
Please cite this article as: Manca A, Mohamad F, Ahmad A, Mohd Sofa MFA, Ismail N, Tri-spine horseshoe crab, Tachypleus tridentatus (L.) in Sabah, Malaysia: the adult body sizes and population, Journal of Asia-Pacific Biodiversity (2017), doi: 10.1016/j.japb.2017.04.011. This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
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Tri-spine horseshoe crab, Tachypleus tridentatus (L.) in Sabah, Malaysia: the adult body sizes and population
Mohd Sofaa,b, and Noraznawati Ismaila,c
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Corresponding author: [email protected]
Horseshoe Crab Research Group (HCRG)
b
School of Marine and Environmental Sciences
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a
c
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Azwarfarid Mancaa,b, Faridah Mohamada,b,*, Amirrudin Ahmada,b, Muhd Fawwaz Afham
Institute of Marine Biotechnology, Universiti Malaysia Terengganu, 21030 Kuala
ABSTRACT
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Terengganu, Terengganu, Malaysia.
Dwindling number of the tri-spine horseshoe crab, T. tridentatus has been reported globally.
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Similar case is also seen in Malaysia, specifically in Sabah where locals claim that the animal
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is less seen in the present compared to previous years. However, there is no scientific data on its population status. Capture-mark-recapture (CMR) method were carried out from October 2014 through September 2015 to estimate the abundance of adult T. tridentatus in Tawau, Sabah. Samples were also weighed and examined for their body parameters (i.e. prosomal width, carapace length, telson length, total length, intraocular distance). The estimated population sizes of T. tridentatus ranged from 182-1,095 with 95% confident limits of 5642,942 individuals (Schnabel formula). Multivariate Discriminant Hotelling T2 test verifies the sexual size dimorphism among the adult T. tridentatus with 97.7% separation among
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ACCEPTED MANUSCRIPT sexes (Hotelling T2=778.49, F=152.85, p<0.001) with female being larger and heavier than the male individuals. The number estimated from the study is the first being reported for T. tridentatus in Malaysia, particularly in Sabah. Even though this number may slightly overestimate the actual population size in the area owing to the low number of individuals
Keywords:
Tachypleus
tridentatus,
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recaptured, for now it could serve as baseline data for horseshoe crab management purpose.
capture-mark-recapture,
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horseshoe crab, Sabah, Malaysia.
population,
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abundance,
ACCEPTED MANUSCRIPT Introduction There are four horseshoe crabs in the world nowadays. These horseshoe crabs distributed widely with one species confined to the Atlantic Ocean namely the American horseshoe crab Limulus polyphemus that distributed widely within the geographic ranges from 21° to 44° N
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and 68° to 90° W covers the area of Maine in the North of America (Sekiguchi and Shuster 2009; Shuster 2015), down to Yucatan in the Gulf of Mexico (Zaldivar-Rae et al 2009) with the highest population recorded in Delaware Bay (Sekiguchi and Shuster 2009; Walls et al
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2002). The other three horseshoe crab species (known as the Asian horseshoe crabs) namely coastal horseshoe crab Tachypleus gigas, tri-spine horseshoe crab T. tridentatus and
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mangrove horseshoe crab Carcinoscorpius rotundicauda distributed in Indo-pacific Ocean that range from 6° S to 31° N and between 90° to 118° E (Sekiguchi and Shuster 2009) covering the Bay of Bengal in India to Philippines and from South-West Japan down to China, Thailand, Malaysia and Indonesia in the south (Carmichael and Brush 2012; Chatterji
waters.
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1994). Recent recovery by Yang and Ko (2015) also reported T. tridentatus in the Korean
Tachypleus tridentatus is one of the three Asian horseshoe crab species available in
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Malaysia, with a distribution limited to East Malaysia only. The horseshoe crabs were
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utilized by locals mainly for the human consumption as delicacies, especially the egg-bearing female (Christianus and Saad 2009; Faridah et al 2015) that typically sell for a price of MYR20 (~5 USD) per individual in local wet market. The horseshoe crabs were also used in traditional remedies for treating joint pains and fever (Basudev et al 2013; Mishra 2009; Pradeep and Srijaya 2010). In certain area of Sabah, locals used to hang T. tridentatus carcasses in their homes for protection from bad spirit apart from ornamental purpose. Declining number of T. tridentatus population was reported globally specifically in China and Japan. Rapid development to produce TAL kit has been reported in China (Gauvry
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ACCEPTED MANUSCRIPT 2015), where T. tridentatus were previously harvested on a large scale for their blood for TAL production. Recently, it is reported that the adult T. tridentatus were rarely seen compared to the past 30-40 years (Berkson et al 2009; Shin et al 2009). As a result, intensive research on monitoring the population of the juvenile T tridentatus has been conducted in
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China especially in Hong Kong and Taiwan with the aim to address the issue for restoring the horseshoe crab population in the areas (Chen et al 2004; Chen et al 2010; Hu et al 2009; Kwan et al 2016; Morton and Lee 2011).
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Similar patterns have been reported in Japan where rapid development of land reclamation caused a significant decline of T. tridentatus population number (Seino et al
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2003; Tsuchiya 2009). Even with such great management for the conservation purpose, the population of T. tridentatus in Japan remained low. Five years spawning population surveys conducted by Wada et al (2010) in Tsuyazaki Coast in Fukuoka, Japan reported a consistent reduction of spawning pairs from 139 recorded in 2002 to only 40 pairs in 2008 and is
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expected to continuously decrease in the coming years.
Unfortunately, there is a lack of literature on T. tridentatus population in Malaysia, compared to both T. gigas and C. rotundicauda in Peninsular Malaysia (e.g. Faridah et al
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2015; Ismail and Sarijan 2011; Manca et al 2016; Nelson et al 2015; Srijaya et al 2010; Tan
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et al 2012; Zaleha et al 2012). In fact, no specific research has been conducted to update the current population status of T. tridentatus in Sabah. Local anecdotal reports of the decreasing number of T. tridentatus have urged the need to obtain a scientific data on T. tridentatus abundance. As T. tridentatus is listed as data deficient in IUCN red list (IUCN 2015), any information on this animal will be valuable to update the information on this animal. This study was carried out to address the research gap as mentioned above with the aims to (i) estimate the population size of adult T. tridentatus in Tawau waters, (ii) determine the
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ACCEPTED MANUSCRIPT sex ratio of the offshore adult T. tridentatus, and (iii) evaluate the morphometric variation among sexes.
Materials and Methods
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Sampling site
This study was carried out in Tawau that located in the south-east region of Sabah in the
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Malaysian Borneo, facing the Celebes Sea (Figure 1). The fishermen village is situated on the edge of the mainland with most of the ‘amphibian’ houses are built on poles along the
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intertidal coastline. This densely populated area is inhabited by approximately 3,000 residents with most of the villagers are fishermen, is subject to heavy fishing activities with active aqua farming ponds in the vicinity. The presence of fish landing jetties confirms the importance of this area in the local fisheries industry. The land areas are dominated by oil palm trees, with
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patches of common dwarf tropical mangrove plants such as Rhizophora spp. and Bruguiera spp., whereas bigger mangrove apples (Sonneratia spp.) trees dominated the seawards area. The study was carried out in five months during a sampling duration from October 2014
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through September 2015. This site was selected based on the availability of T. tridentatus as
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confirmed from the site visit conducted in 2014.
Samples collection
Samples of adult T. tridentatus were collected using gill-net that deployed into the sea down to 5 m depth, approximately 1-3 km from the shore. The net (mesh size 11.4 cm, 1.0 m height × 400 m length; a type of net commonly used by fishermen to capture crabs in the study area) were deployed with at least 24 hours soaking time. After 24 hours, the net was hauled and all tangled horseshoe crabs were removed from the net and placed in the boat for
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ACCEPTED MANUSCRIPT marking protocol. Captured horseshoe crabs were recorded, examined for their sex based on the presence of pedipalps (clasper) on the first and second pairs of walking leg, measured for their body parameters and weighed using a digital balance (model DJC31G-30) before
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released into the water at the capture point.
Estimation population size: capture-mark-recapture (CMR) methods.
In general, 15 CMR samplings were conducted within the five months sampling period.
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The horseshoe crab samples were captured using the method mentioned in Section 2.2. All tangled horseshoe crabs were marked with white button tag that bears a unique individual
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number on the left side of the prosoma (latero-posterior point) before released at the capture point (see Faridah et al 2015; Mattei and Beekey 2008). A total of three CMR samplings were carried out per month with at least 48 hours gap between each samplings. These time gap is to allow the marked individuals to recover and mingle with the unmarked population
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before the next sampling.
The estimation of T. tridentatus abundance in Tawau waters was calculated using
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follows:
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Schnabel formula with an assumption of closed population (Krebs 1999). The formula is as
′
=
∑ ∑ 1
′
+ 1 =
1 = ′
6
∑
1 ′
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Where, N’ = the estimated population size, Ct = the total number of individuals captured in sample t,
Rt = the recaptured individuals during the sample t.
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Measurement of body parameters
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Mt = the cumulative number of marked individuals before the t sample, and
All netted T. tridentatus were examined for their sex and measured for their body
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parameters using a measuring tape to the nearest 0.1 cm. Each individual of T. tridentatus was measured for five body parameters which were prosomal width (PW); the widest part of the prosoma measured across the ventral side, carapace length (CL); the length from the tip of prosoma to the anus, telson length (TEL); the length of rigid tail from the anus to the end of
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tail projection, total length (TL); the total length from the tip of prosoma to the end of tail, and intraocular distance (IO); distance between the two compound eyes as depicted in Figure 2. All measured individuals had a full complement of body forms with no visible body
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deformations. Those horseshoe crabs with damaged, injured or regenerated body partss were
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excluded from analysis and released into the water immediately upon captures.
Statistical analysis
Morphometric data of from the collected T. tridentatus were pooled according to sex and sampling months. The variation of sex ratio among T. tridentatus was tested using Chi2 test, whereas Independent-samples t-test was run to determine the significant difference of mean for each body parameters between male and female individuals. Multivariate Discriminant Hotelling T2 test was run to verify the discreteness between sexes of T. tridentatus in the
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Results and discussion Abundance of T. tridentatus in Tawau waters
A total of 271 catches from 267 individuals T. tridentatus were recorded throughout the
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samplings. The number of captured individuals varied among the months with highest recorded in October with 113 individuals representing 41.7% from the total catch. This
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followed by February and September with 50 (18.5%) and 46 (17.0%) individuals respectively. Lowest individuals captured were recorded in April with 29 (10.7%) individuals.
The CMR sampling recorded very low recaptured individuals with only four individuals
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(1.5% recapture rates) from the total catch. Of these, two individuals were recaptured within the same sampling month; i.e. one female (tag ID 1329) that marked on second sampling day was recaptured on the third sampling day in October 2014, whereas another female (tag ID
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1487) was recaptured on the second day CMR in September 2015. Two more individuals
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were recaptured later on different sampling months (Table 1). One male (tag ID 1302) marked during October 2014 was recaptured four months later in February 2015, and sampling conducted in April recorded another recaptured male (tag ID 1434) that was marked in February. Similar pattern of low recaptured individuals were reported in Faridah et al (2015) study as only six total recaptured individuals were reported in their CMR study on T. gigas population in Pahang waters. A 17-year tagging study by Swan (2005) reported only about 7% recovery of the marked L. polyphemus. Such low recaptured individuals might be
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Sabah waters. Since there is no comparable data from previous study, it cannot be assured whether these numbers represent the growing population of T. tridentatus in the areas or showing a decrease in number over the past decades as claimed by locals. However, these
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numbers indicate very low population size as compared to the estimated number of L. polyphemus in the USA. For instance, Smith et al (2006) estimate that L. polyphemus
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population in Delaware Bay was 20 million (90% confidence interval of 13-28 million) individuals. Moreover, Engel (2005) reported that during their 2004 survey, there were 259,000 and 63,000 L. polyphemus in both Slaughter and Bower beaches respectively. These estimated population numbers in the USA were based on the spawning population that
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congregates onshore to nest during the spawning season, whereas the present study reported the offshore population which is not in the spawning mode. It is suspected that the spawning population T. tridentatus might be even lower based on the evidence from previous study in
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all Asian horseshoe crab species (e.g. Behera et al 2015; Botton et al 1996; Cartwright-Taylor
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et al 2011; Manca et al 2016; Mattei et al 2010; Seino et al 2003; Shin et al 2009; Wada et al 2010).
Several studies on the offshore population of horseshoe crabs as conducted by Hata and Berkson (2003) in USA reported higher population size with an average of 6.8-11.4 million individuals within 22.2 km offshore. The current findings only represent approximately 0.01% from the offshore L. polyphemus in Hata and Berkson’s study. Similarly, there is higher number of the offshore T. gigas in Pahang on the east coast of Peninsular Malaysia with 7,140 and 9,900 individuals in Chendor and Cherating waters respectively (Faridah et al
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resulted from higher recapture individuals. Owing to the extremely low recapture rate, in addition to an extended sampling duration and repeated monitoring, it is even more important to obtain higher
recaptures in each CMR sampling events. Therefore, a larger sampling
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annually for monitoring purpose.
Sex ratio of T. tridentatus population in Tawau
The overall sex ratio of the offshore T. tridentatus were skewed to males with 2.08:1 male to female ratio. Only April shows the reverse (Table 1). Similar findings were reported
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for the offshore T. gigas in Pahang, Malaysia with higher male-bias of 14:1 (Faridah et al 2015). Brockmann et al (2015) speculated that the male-skewed population in horseshoe crab populations occurs in the regions where females were preferable to be harvested. This agrees
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with the previous report of commercial harvest of egg-bearing females T. gigas to be
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consumed as local dishes or exported to fulfill market demands (Christianus and Saad 2009; Faridah et al 2015; Ismail et al 2012; Robert et al 2014). In contrast, the male-biased sex ratio somehow is common for L. polyphemus population especially the spawning population on breeding beaches. It was reported that male numbers were consistently higher than the female (Brockmann and Johnson 2011; Carmichael et al 2003; James-Pirri et al 2005; Rudloe 1980; Shuster and Botton 1985; Smith et al 2006, 2010) with up to 15 males per female (Loveland and Botton 1992; Engel 2005). Extreme male-bias in spawning population of L. polyphemus with the presence of spawning group (Brockmann
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et al (1996) mentioned that lack of male-bias in the Asian horseshoe crab spawning population was likely due to low population number that led to no mating competition among the male Asian horseshoe crabs. This suggests that the population size estimated in the
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current study may represent the non-spawning population as higher male-bias recorded which
Measurement of body parameters
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is unlikely to be the case for the spawning Asian horseshoe crabs.
Table 3 shows the descriptive statistic for both male and female T. tridentatus collected in Tawau waters in Sabah. All individuals were adult individuals with PW size ranged from
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20.0-29.8 (mean±SD; 25.7±1.6) cm and weight of 600-1700 g for males whereas, 24.2-36.2 (31.2±2.3) cm and weight of 1400-4000 g for females. Sekiguchi et al (1988) throughout their 10-year rearing of T. tridentatus in the lab concluded that T. tridentatus reach the adult
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stage with mean PW (±SD) of 24.4±1.9 cm and 27.8±1.7 cm for male and female
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respectively. However, Wada et al (2010) reported smaller size of mature individuals collected from wild spawning pairs in Tsuyazaki coast, Fukuoka, Japan with a mean of 22.6 cm for male and 27.6 cm for female. This suggests that horseshoe crabs in the wild may reach maturity at a smaller size as compared to the reared individuals which might be due to environmental stressor probably by insufficient food resources (Blankenhorn 2000). It was also reported that the horseshoe crabs may reach maturity with variable size based on the evidence of discrete PW sizes among the horseshoe crab populations from different localities (Sekiguchi and Shuster 2009).
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ACCEPTED MANUSCRIPT It was confirmed that female T. tridentatus were significantly larger in PW (t=-20.56, p<0.001), CL (t=-24.45, p<0.001), TEL (t=-10.67, p<0.001), TL (t=-17.96, p<0.001), and IO (t=-26.12, p<0.001) as shown in Table 3. This proved that females T. tridentatus do reach maturity with an additional instar stage than the males as proposed by Sekiguchi et al (1988).
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Female T. tridentatus reach maturity after 16 times molting in the 14th year, one additional instar stage from male individuals that mature with only 15 times in the 13th year. Carmichael et al (2015) recently speculated that female horseshoe crabs may possibly molt at
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least once after mating (i.e. post-reproductive molting) before reaching their terminal molt. Based on the presumed size from Sekiguchi et al (1988), both male and female T. tridentatus
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collected in Sabah were on their 16th and 17th instar stages respectively, confirming that collected individuals were adult individuals with different instar stages, thus explained the significantly larger size in female body parameters compared to male T. tridentatus. The PW in females collected were consistently larger than the males throughout the sampling months
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(Figure 3). This SSD is also shown by mangrove horseshoe crabs C. rotundicauda in Singapore (Cartwright-Taylor et al 2009).
The body parameters in male and female T. tridentatus were significantly distinct with
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97.7% separation between the sexes (Multivariate Discriminant Hotelling T2=778.49,
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F=152.85, p<0.001), suggesting that it is appropriate for determination of sexual size dimorphism in T. tridentatus population in Sabah waters. Cartwright-Taylor et al (2009) and Loveland and Botton (1992) mentioned that SSD in horseshoe crabs was demonstrated by female being larger than male even though there is a slight overlapping of size between the largest male and the smallest female. This might be the result of their mating system where females use their large body to tow the male that clings on their opisthosomal spines (i.e. amplexus) during the spawning seasons. It was reported that the amplexus pair may remain more than a week (Botton et al 1996; Robert et al 2014). Suggs et al (2002) speculated that
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ACCEPTED MANUSCRIPT some size-based mate selection may occur among the spawning horseshoe crabs in which the males tended to prefer larger-size females to perform amplexus. This might be due to the fact that larger females may possibly be more productive and bear more eggs in their body.
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Conclusion
The adults T. tridentatus exhibit sexual size dimorphisms with female being significantly larger than the males. Their population in Sabah waters is estimated to range from 182-1,095
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(95% confidence limits of 56-42,942) individuals with male-biased sex ratio of 2.08:1. This is the first report on the population size of adult T. tridentatus in Sabah waters, providing a
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baseline data of T. tridentatus population in Malaysia. The approach used in this study could be applied annually in the monitoring and management plans for the species in Sabah.
Conflict of interest
Acknowledgments
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The authors declare that there is no conflict of interest.
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This study was funded by Sabah Biodiversity Center, SaBC [grant number: TJ 66917].
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The authors would like to thank Universiti Malaysia Terengganu, UMT for the facilities provided, and the villagers/fishermen in Tawau for their help and inputs during the sampling period.
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ACCEPTED MANUSCRIPT References
Askey PJ, Post JR, Parkinson EA, et al. 2007. Estimation of gillnet efficiency and selectivity
RI PT
across multiple sampling units: a hierarchical Bayesian analysis using mark-recapture data. Fisheries Research 83:162-174.
Basudev T, Sivakumar K, Sajan J, et al. 2013. Assessment of the population status and threats
SC
to the horseshoe crabs along the northern east coast of India. In: Venkataraman K, Sivaperuman C, Raghunathan C, editors. Ecology and conservation of tropical marine
M AN U
faunal communities. New York: Springer. pp 137-146.
Behera S, Tripathy B, Sivakumar K, et al. 2015. Distribution and abundance of two sympatric species of horseshoe crabs along the Odisha Coast, India. In: Carmichael RH, Botton ML, Shin PKS, et al, editors. Changing global perspectives on horseshoe crab biology,
TE D
conservation and management. New York: Springer. pp 181-191. Berkson J, Chen CP, Mishra J, et al. 2009. A discussion of horseshoe crab management in
EP
five countries: Taiwan, India, China, United States, and Mexico. In: Tanacredi JT, Botton ML, Smith DR, editors. Biology and conservation of horseshoe crabs. New York,
AC C
Springer. pp 465-475.
Blanckenhorn WU. 2000. The evolution of body size: what keeps organism small? The Quarterly Review of Biology 75(4):385-407. Botton ML, Shuster CN Jr, Sekiguchi K, et al. 1996. Amplexus and mating behavior in the Japanese horseshoe crab, Tachypleus tridentatus. Zoological Science 13:151-159. Brockmann HJ, Johnson SL, Smith MD, et al. 2015. Mating tactics of the American horseshoe crab (Limulus polyphemus). In: Carmichael RH, Botton ML, Shin PKS, et al,
14
ACCEPTED MANUSCRIPT editors. Changing global perspectives on horseshoe crab biology, conservation and management. New York: Springer. pp 321-352. Brockmann HJ, Johnson SL. 2011. A long-term study of spawning activity in a Florida Coast
1067.
RI PT
population of horseshoe crabs (Limulus polyphemus). Estuaries and Coasts 34:1049-
Brockmann HJ, Nguyen C, Potts W. 2010. Paternity in horseshoe crabs when spawning in
SC
multiple-male groups. Animal Behaviour 60:837-849.
Carmichael RH, Brush E. 2012. Three decades of horseshoe crabs rearing: a review of
M AN U
conditions for captive growth and survival. Reviews in Aquaculture 4:32-43. Carmichael RH, Hieb EE, Gauvry G, et al. 2015. Examination of large exuviae with mating scars: do female American horseshoe crabs, Limulus polyphemus, molt after sexual maturity? In: Carmichael RH, Botton ML, Shin PKS, et al, editors. Changing global
Springer. pp 353-368.
TE D
perspectives on horseshoe crab biology, conservation and management. New York:
EP
Carmichael RH, Rutecki D, Valiela I. 2003. Abundance and population structure of the Atlantic horseshoe crab Limulus polyphemus in Pleasant Bay, Cape Cod. Marine
AC C
Ecology Progress Series 246:225-239. Cartwright-Taylor L, Bing YV, Chi HC, et al. 2011. Distribution and abundance of horseshoe crabs Tachypleus gigas and Carcinoscorpius rotundicauda around the main island of Singapore. Aquatic Biology 13:127-136. Cartwright-Taylor L, Lee J, Hsu CC. 2009. Population structure and breeding pattern of the mangrove horseshoe crab Carcinoscorpius rotundicauda in Singapore. Aquatic Biology 8:61-69.
15
ACCEPTED MANUSCRIPT Cartwright-Taylor L. 2015. Studies of horseshoe crabs around Singapore. In: Carmichael RH, Botton ML, Shin PKS, et al, editors. Changing global perspectives on horseshoe crab biology, conservation and management. New York: Springer. pp 193-211.
RI PT
Chatterji A. 1994. The horseshoe crab – a living fossil. Orissa: Project Swarajya Publication. Chen CP, Yeh HY, Lin PF. 2004. Conservation of the horseshoe crab at Kinmen, Taiwan: strategies and practices. Biodiversity and Conservation 13:1889-1904.
SC
Chen Y, Lau CW. Cheung SG, et al. 2010. Enhanced growth of juvenile Tachypleus tridentatus (Chelicerata: Xiphosura) in the laboratory: a step towards population
M AN U
restocking for conservation of the species. Aquatic Biology 11:37-46.
Christianus A, Saad CR. 2009. Traditional uses of horseshoe crabs in Malaysia and Thailand. In: Tanacredi JT, Botton ML, Smith DR, editors. Biology and conservation of horseshoe
TE D
crabs. New York: Springer. pp 616.
Engel E. 2005. Trailing the ancient mariner. The Chesapeake’s Independent Newspaper Online 13(25):1-5.
EP
Faridah M, Ismail N, Ahmad BA, et al. 2015. The population size and movement of coastal
AC C
horseshoe crab, Tachypleus gigas (Muller) on the east coast of Peninsular Malaysia. In: Carmichael RH, Botton ML, Shin, PKS, et al, editors. Changing global perspectives on horseshoe crab biology, conservation and management. New York: Springer. pp 213228.
Gauvry G. 2015. Current horseshoe crab harvesting practices cannot support global demand for TAL/LAL: the pharmaceutical and medical devices industries’ role in the sustainability of horseshoe crabs. In: Carmichael RH, Botton ML, Shin PKS, et al,
16
ACCEPTED MANUSCRIPT editors. Changing global perspectives on horseshoe crab biology, conservation and management. New York: Springer. pp 475-500. Hammer Ø, Harper DAT, Ryan PD. 2001. PAST: Paleontological statistics software package
RI PT
for education and data analysis. Palaeontologia Electronica 4:9. Hata D, Berkson J. 2003. Abundance of horseshoe crabs (Limulus polyphemus) in the Delaware Bay area. Fishery Bulletin 101(4):933-938.
SC
Hu M, Wang Y, Chen Y, et al. 2009. Summer distribution and abundance of juvenile Chinese horseshoe crabs Tachypleus tridentatus along an intertidal zone in southern China.
M AN U
Aquatic Biology 7:107-112.
Ismail N, Jolly JJ, Dzulkiply SK, et al. 2012. Allometric variations of horseshoe crab (Tachypleus gigas) populations collected from Chendor and Cherating, Pahang,
TE D
Peninsular Malaysia. Journal of Sustainability Science and Management 7(2):164-169. Ismail N, Sarijan S. 2011. Phylogenetic inference from 18S rRNA gene sequences of horseshoe crabs, Tachypleus gigas between Tanjung Dawai, Kedah and Cherating,
EP
Pahang, Peninsular Malaysia. International Journal of Biological, Agricultural and Food
AC C
Engineering 5(8):66-69. IUCN
(International
Union
for
Conservation
of
Nature).
2015.
Available
at:
http://www.iucnredlist.org/details/21309/0. [Date accessed: 15 August 2016]. James-Pirri MJ, Tuxbury K, Marino S, et al. 2005. Spawning densities, egg densities, size structure, and movement patterns of spawning horseshoe crabs, Limulus polyphemus, within four coastal embayments on Cape Cod, Massachusetts. Estuaries 29(2):296-313.
17
ACCEPTED MANUSCRIPT Krebs CJ. 1999. Ecological methodology, 2nd ed. London: Addison-Welsey Educational Publishers Inc. Kwan BKY, Hsieh HL, Cheung SG, et al. 2016. Present population and habitat status of threatened
Asian
horseshoe
crabs
Tachypleus
tridentatus
and
RI PT
potentially
Carcinoscorpius rotundicauda in Hong Kong: a proposal for marine protected areas. Biodiversity and Conservation 25(4):673-692.
SC
Loveland RE, Botton ML. 1992. Size dimorphism and the mating system in horseshoe crabs, Limulus polyphemus L. Animal Behaviour 44(5):907-916.
M AN U
Manca A, Mohamad F, Nelson BR, et al. 2016. Trailing the spawning horseshoe crab Tachypleus gigas (Müller, 1785) at designated natal beaches on the East Coast of Peninsular Malaysia. Cell and Developmental Biology 5(171):1-6. Mattei JH, Beekey MA, Rudman A, et al. 2010. Reproductive behavior in horseshoe crabs:
TE D
does density matter? Current Zoology 56(5):634-642. Mattei JH, Beekey MA. 2008. The horseshoe crab conundrum: can we harvest and conserve?
EP
Wrack Lines 8(1):2-7.
AC C
Mishra JK. 2009. Horseshoe crabs, their eco-biological status along the Northeast Coast of India and the necessity for ecological conservation. In: Tanacredi JT, Botton ML, Smith DR, editors. Biology and conservation of horseshoe crabs. New York: Springer. pp 8996.
Moore S, Perrin S. 2007. Seasonal movement and resource-use patterns of resident horseshoe crabs (Limulus polyphemus) populations in a Maine, USA estuary. Estuaries and Coasts 30(6):1016-1026.
18
ACCEPTED MANUSCRIPT Morton B, Lee CN. 2011. Spatial and temporal distribution of juvenile horseshoe crabs (Arthropoda: Chelicerata) approaching extirpation along the northwestern shoreline of the new territories of Hong Kong SAR, China. Journal of Natural History 45(3-4):227-
RI PT
251. Nelson BR, Satyanarayana B, Zhong JMH, et al. 2015. Episodic human activities and seasonal impacts on the Tachypleus gigas (Müller, 1785) population at Tanjung Selangor
SC
in Peninsular Malaysia. Estuarine, Coastal and Shelf Science 164:313-323.
Pradeep PJ, Srijaya TC. 2010. A primitive ancient wonder – horseshoe crab. Science India: 4-
M AN U
11.
Robert R, Muhammad Ali SH, Amelia-Ng PF. 2014. Demographics of horseshoe crab populations in Kota Kinabalu, Sabah, Malaysia with emphasis on Carcinoscorpius rotundicauda and some aspects of its mating behaviour. Journal of Tropical Agricultural
TE D
Science 37(3):375-388.
Rudloe A. 1980. The breeding behavior and patterns of movement of horseshoe crabs,
EP
Limulus polyphemus, in the vicinity of breeding beaches in Apalachee Bay, Florida. Estuaries 3(3):177-183.
AC C
Seino S, Uda T, Tsuchiya Y, et al. 2003. Conservation history of horseshoe crab Tachypleus tridentatus and its spawning ground, a designated natural monument in Kasaoka Bay in Okayama prefecture. Asian and Pacific Coasts: 1-14. Sekiguchi K, Seshimo H, Sugita, H. 1988. Post-embryonic development of the horseshoe crab. Biological Bulletin 174:337-345. Sekiguchi K, Shuster Jr CN. 2009. Limits on the global distribution of horseshoe crab (Limulacea): lessons learned from two lifetimes of observations: Asia and America. In:
19
ACCEPTED MANUSCRIPT Tanacredi JT, Botton ML, Smith DR, editors. Biology and conservation of horseshoe crabs. New York: Springer. pp 5-24. Shin PKS, Li HY, Cheung SG. 2009. Horseshoe crabs in Hong Kong: current population
RI PT
status and human exploitation. In: Tanacredi JT, Botton ML, Smith DR, editors. Biology and conservation of horseshoe crabs. New York, Springer. pp 347-360.
Shuster CN Jr, Botton ML. 1985. A contribution to the population biology of horseshoe
SC
crabs, Limulus polyphemus (L.), in Delaware Bay. Estuaries 8(4):363-372.
Shuster CN Jr. 2015. The Delaware Bay area, U.S.A.: a unique habitat of the American
M AN U
horseshoe crab, Limulus polyphemus. In: Carmichael RH, Botton ML, Shin PKS, Cheung SG, editors. Changing global perspectives on horseshoe crab biology, conservation and management. New York: Springer. pp 15-40.
Smith DR, Brousseau LJ, Mandt MT, et al. 2010. Age and sex specific timing, frequency, and
TE D
spatial distribution of horseshoe crab spawning in Delaware Bay: Insights from a largescale radio telemetry array. Current Zoology 56(5):563-574.
EP
Smith DR, Millard MJ, Eyler S. 2006. Abundance of adult horseshoe crabs (Limulus polyphemus) in Delaware Bay estimated from a bay-wide mark-recapture study. Fishery
AC C
Bulletin 104:456-464.
Srijaya TC, Pradeep PJ, Mithun S, et al. 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. Suggs DN, Carmichael RH, Grady SP, et al. 2002. Effects of individual size on pairing in horseshoe crabs. Biological Bulletin 203:225-227.
20
ACCEPTED MANUSCRIPT Tan AN, Christianus A, Shakibazadeh S, et al. 2012. Horseshoe crab, Tachypleus gigas (Müller, 1785) spawning population at Balok beach, Kuantan, Pahang, Malaysia. Pakistan Journal of Biological Sciences 15(13):610-620.
RI PT
Tsuchiya K. 2009. The history of horseshoe crab research and conservation in Japan. In: Tanacredi JT, Botton ML, Smith DR, editors. Biology and conservation of horseshoe crabs. New York: Springer. pp 559-570.
SC
Wada T, Itaya S, Shuuno M. 2010. Spawning sites and annual variability of the number of reproductive visiting pairs of the horseshoe crab Tachypleus tridentatus along the
M AN U
Tsuyazaki Coast in Fukuoka, Japan. Japanese Journal of Conservation Ecology 15:163171.
Walls EA, Berkson J, Smith SA. 2002. The horseshoe crab, Limulus polyphemus: 200 million years of existence, 100 years of study. Reviews in Fisheries Science 10:39-73.
TE D
Yang KC, Ko SH. 2015. First record of tri-spine horseshoe crab, Tachypleus tridentatus (Merostomata: Xiphosurida: Limulidae) from Korean waters. Animal Systematics,
EP
Evolution and Diversity 31:42-45.
Zaldívar-Rae J, Sapién-Silva E, Rosales-Raya M, et al. 2009. American horseshoe crabs,
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Limulus polyphemus, in Mexico: open possibilities. In: Tanacredi JT, Botton ML, Smith DR, editors. Biology and conservation of horseshoe crabs. New York: Springer. pp 97114.
Zaleha K, Akbar John B, Erni Atika H, et al. 2012. Spawning and nesting behaviour of Tachypleus gigas along the East Coast of Peninsular Malaysia. International Journal of Biology 4(2):102-111.
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ACCEPTED MANUSCRIPT Figure captions Figure 1.
Map showing the location of sampling site as indicated by an arrow. Inset shows both Peninsular and East Malaysia with Sabah state highlighted in
Figure 2.
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green.
The measurement of T. tridentatus morphological parameters. (PW, prosomal width; CL, carapace length; TEL, telson length; TL, total length; and IO,
Figure 3.
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for each morphological measurements.
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intraocular distance). Image of male T. tridentatus is shown with an example
The variation of prosomal width of male and female T. tridentatus in different sampling months in Tawau, Sabah. The prosomal width in females were consistently larger than the males (two sample t-test; p<0.001). Box shows
Descriptive summary of pooled capture-mark-recapture (CMR) data and sex
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Table 1
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median and quartiles, whiskers are 95% confidence interval.
ratios of T. tridentatus population in Tawau, Sabah. Few mortalities recorded
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in April, July and September 2015 led to the reduction of marked and released individuals.
Table 2
The population size of T. tridentatus estimated from Schnabel formula. Some parameters cannot be computed for February, April, and July as there were no recaptured individuals recorded during the sampling.
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The mean±SD (range) of body parameters (cm) for male and female T.
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tridentatus collected from Tawau waters.
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Table 1
Descriptive summary of pooled capture-mark-recapture (CMR) data and sex ratios of T. tridentatus population in Tawau, Sabah. Few mortalities recorded
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in April, July and September 2015 led to the reduction of marked and released individuals.
The population size of T. tridentatus estimated from Schnabel formula. Some
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Table 2
parameters cannot be computed for February, April, and July as there were no
Table 3.
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recaptured individuals recorded during the sampling.
The mean±SD (range) of body parameters (cm) for male and female T.
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tridentatus collected from Tawau waters.
Table 1 Month
Total Caughta
Recaptured Total marked Sex Ratio Individuals and Releasedb (Male:Female)
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Year
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χ2
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Male Female 2014 October 80 33 1c 112 2.42:1 s d 2015 February 42 8 1 49 5.25:1 s April 13 16 1d 25 0.81:1 n/s July 19 14 0 29 1.36:1 n/s 17 1c 40 1.71:1 n/s September 29 Total 183 88 4 255 2.08:1 s a = total individuals captured from pooled CMR session according to months, b = total individuals that marked and released alive, c = individuals recaptured within the same sampling month, d = individuals recaptured on different sampling month, s = significant, n/s = not significant.
Table 2
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Sampling Months Oct 14 Feb 15 Apr 15 Jul 15 Pop. Size (N) 1,095 669 182 320 Variance 2.085 × 10-7 n/a n/a n/a -4 n/a n/a n/a Standard Error 4.566 × 10 Lower 95% CL 412 204 56 98 Upper 95% CL 42,942 n/a n/a n/a N = population size estimate, CL = confidence limits, n/a = not available.
Sep 15 304 2.705 × 10-6 1.645 × 10-3 115 11,922
Table 3
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Body Parameters (cm) PW CL TEL TL a a a Male 25.7±1.6 25.1±1.7 28.6±3.5 53.8±4.6a (n=154) (20.0-29.8) (20.0-32.6) (20.0-38.0) (41.0-65.7) b b b Female 31.2±2.3 32.1±2.4 34.6±4.5 66.7±5.6b (n=67) (24.2-36.2) (26.5-39.5) (17.0-42.7) (47.5-79.5) PW=prosomal width, CL=carapace length, TEL=telson length, TL=total IO=intraocular distance. a and b indicate significant difference at p<0.001 (Independent-samples t-test)
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IO 13.8±0.9a (11.0-16.1) 17.7±1.3b (14.0-21.2) length, and
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