Papers by Azwarfarid Manca
Journal of Crustacean Biology, 2019
Horseshoe crab populations are declining worldwide, and Tachypleus tridentatus (Leach, 1819) has ... more Horseshoe crab populations are declining worldwide, and Tachypleus tridentatus (Leach, 1819) has recently been classified as Endangered in the IUCN Redlist. Among the keys for species survival is successful reproduction. Although there are reports on the reproduction, particularly details on the spawning behaviour, of the American species, Limulus polyphemus (Linnaeus, 1758), information on Southeast Asia species is very scant. This field study reports the nesting activities of T. tridentatus at Jambongan Island, Sabah, Malaysia. Observation were carried out on 16 spawning pairs that were spotted during full and new moon from April-July 2016 in Sabah. Nest placements, number of nests, number of eggs, time spent at each nest, and nest widths, depth, and distance from the highest tide line were recorded for each pair. Tachypleus tridentatus generally laid an average of 967 ± 54.1 eggs/nest (171–2,282) in as many as nine nests on the intertidal zone between 125 and 940 cm from the high...
Bookmarks Related papers MentionsView impact
Journal of Asia-Pacific Biodiversity, 2017
Bookmarks Related papers MentionsView impact
Cell & Developmental Biology, 2016
Bookmarks Related papers MentionsView impact
Changing Global Perspectives on Horseshoe Crab Biology, Conservation and Management, 2015
Bacteria associated with marine organisms have received major attention worldwide due to their po... more Bacteria associated with marine organisms have received major attention worldwide due to their potential in pharmaceutical industries. A total of 32 bacterial strains were isolated and identified, 22 from Tachypleus gigas and 10 from Carcinoscorpius rotundicauda from Balok Beach, Malaysia. Overall, Gram-negative bacteria showed dominancy on both species. A combination of biochemical tests, macro morphology, and micro morphology was used to roughly determine genus of bacterial isolates; where results from 16S rDNA sequencing were taken as the end results due to its high reliability. Results from the molecular approach showed only Pseudoalteromonas sp. (38.46 %), Vibrio sp. (46.15 %), and Photobacterium sp. (15.38 %) might exhibit mutualism with horseshoe crabs, T. gigas and C. rotundicauda. Study on the diversity of bacteria associated with horseshoe crabs can enhance the understanding of these animals and the potential sustainability of producing useful compounds for defense mechanisms.
Bookmarks Related papers MentionsView impact
Changing Global Perspectives on Horseshoe Crab Biology, Conservation and Management, 2015
Horseshoe crabs have recently gained popularity as new exotic delicacies in Malaysia, especially ... more Horseshoe crabs have recently gained popularity as new exotic delicacies in Malaysia, especially in Johor. It has been reported and claimed by some fishermen that horseshoe crabs, particularly females, are being transported in bulk to Thailand. This claim has sparked interest to identify population size and study the behaviour of horseshoe crabs along the east coast of Peninsular Malaysia in an attempt to determine the effect of this demand on the existing population. A study was carried out from December 2011 to March 2012 to determine the coastal horseshoe crab Tachypleus gigas population size in Chendor and Cherating, Pahang, about 10 km apart on the east coast of Peninsular Malaysia, using a Capture-Mark-Recapture method. The sampling was carried out three times at both sites. The population size was calculated using Bailey’s Triple Catch formula with the assumption of an open population. The horseshoe crabs’ ‘traveling distance’ was also determined by attaching numbered, white button tags, each bearing the researcher’s phone number, to a total of 99 horseshoe crab individuals (61 in Chendor, 38 in Cherating). The total estimated populations were 7,140 in Chendor and 9,900 in Cherating. The two populations were found to be interchangeable as the tagged animals from Chendor were recaptured in Cherating and vice versa, thus confirming emigration and immigration. About 25 % of tagged animals were recaptured in various places (at Chendor, Cherating and also outside both locations) as reported by fishermen. Animals tagged in Cherating were caught in a few locations in Pahang, including Tanjung Lumpur which is more than 50 km to the south. Most recaptures (40 %) were from different locations remote from the site where the horseshoe crabs were tagged and released. This study is on-going and notifications are still expected regarding the future location of the tagged animals.
Bookmarks Related papers MentionsView impact
Journal of Ocean University of China
Bookmarks Related papers MentionsView impact
Journal of Crustacean Biology, Oct 10, 2019
Horseshoe crab populations are declining worldwide, and Tachypleus tridentatus (Leach, 1819) has ... more Horseshoe crab populations are declining worldwide, and Tachypleus tridentatus (Leach, 1819) has recently been classified as Endangered in the IUCN Redlist. Among the keys for species survival is successful reproduction. Although there are reports on the reproduction, particularly details on the spawning behaviour, of the American species, Limulus polyphemus (Linnaeus, 1758), information on Southeast Asia species is very scant. This field study reports the nesting activities of T. tridentatus at Jambongan Island, Sabah, Malaysia. Observation were carried out on 16 spawning pairs that were spotted during full and new moon from April-July 2016 in Sabah. Nest placements, number of nests, number of eggs, time spent at each nest, and nest widths, depth, and distance from the highest tide line were recorded for each pair. Tachypleus tridentatus generally laid an average of 967 ± 54.1 eggs/nest (171–2,282) in as many as nine nests on the intertidal zone between 125 and 940 cm from the highest tide. The first nest was dug once the tide began rising, followed by the consecutive nests towards the highest tide line with nest depths ranging between 13 and 22 cm. The complete spawning session (first nest to the last) ended in less than two hours. Time spent in spawning correlates positively with the number of nests and the total number of eggs laid by each spawning female. The spawning area, which is made up mainly by fine and medium-size sediment grains, also experience stable temperature, salinity, and dissolved oxygen conducive for egg-laying and larval development for successful reproduction. The details of spawning are important for planning successful future conservation initiatives for the species, especially in tropical regions.
Bookmarks Related papers MentionsView impact
Journal of Asia-Pacific Biodiversity, 2017
The dwindling number of the tri-spine horseshoe crab, Tachypleus tridentatus has been reported gl... more The dwindling number of the tri-spine horseshoe crab, Tachypleus tridentatus has been reported globally and its status in Malaysia is not much known. Study on dimorphism in adult body sizes and population size estimation were conducted using capture–mark–recapture method of adult T. tridentatus in Tawau, Sabah. The estimated population sizes of T. tridentatus ranged from 182 to 1095 with 95% confident limits of 56–42,942 individuals (Schnabel formula). The multivariate discriminant Hotelling’s T2 test verifies the sexual size dimorphism among the adult T. tridentatus with 97.7% separation among sexes (Hotelling’s T2 = 778.49, F = 152.85, p < 0.001) with females being larger and heavier than the male individuals. The number estimated from the study is the first 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 recaptured, for now it could serve as baseline data for horseshoe crab management purpose.
Bookmarks Related papers MentionsView impact
Springer , 2015
Bacteria associated with marine organisms have received major attention worldwide due to their po... more Bacteria associated with marine organisms have received major attention worldwide due to their potential in pharmaceutical industries. A total of 32 bacterial strains were isolated and identifi ed, 22 from Tachypleus gigas and 10 from Carcinoscorpius rotundicauda from Balok Beach, Malaysia. Overall, Gram-negative bacteria showed dominancy on both species. A combination of biochemical tests, macro morphology, and micro morphology was used to roughly determine genus of bacterial isolates; where results from 16S rDNA sequencing were taken as the end results due to its high reliability. Results from the molecular approach showed only Pseudoalteromonas sp. (38.46 %), Vibrio sp. (46.15 %), and Photobacterium sp. (15.38 %) might exhibit mutualism with horseshoe crabs, T. gigas and C. rotundicauda. Study on the diversity of bacteria associated with horseshoe crabs can enhance the understanding of these animals and the potential sustainability of producing useful compounds for defense mechanisms.
Bookmarks Related papers MentionsView impact
Spinger , 2015
Horseshoe crabs have recently gained popularity as new exotic delicacies in Malaysia, especially ... more Horseshoe crabs have recently gained popularity as new exotic delicacies in Malaysia, especially in Johor. It has been reported and claimed by some fishermen that horseshoe crabs, particularly females, are being transported in bulk to Thailand. This claim has sparked interest to identify population size and study the behaviour of horseshoe crabs along the east coast of Peninsular Malaysia in an attempt to determine the effect of this demand on the existing population. A study was carried out from December 2011 to March 2012 to determine the coastal horseshoe crab Tachypleus gigas population size in Chendor and Cherating, Pahang, about 10 km apart on the east coast of Peninsular Malaysia, using a Capture-Mark-Recapture method. The sampling was carried out three times at both sites. The population size was calculated using Bailey’s Triple Catch formula with the assumption of an open population. The horseshoe crabs’ ‘traveling distance’ was also determined by attaching numbered, white button tags, each bearing the researcher’s phone number, to a total of 99 horseshoe crab individuals (61 in Chendor, 38 in Cherating). The total estimated populations were 7,140 in Chendor and 9,900 in Cherating. The two populations were found to be interchangeable as the tagged animals from Chendor were recaptured in Cherating and vice versa, thus confirming emigration and immigration. About 25 % of tagged animals were recaptured in various places (at Chendor, Cherating and also outside both locations) as reported by fishermen. Animals tagged in Cherating were caught in a few locations in Pahang, including Tanjung Lumpur which is more than 50 km to the south. Most recaptures (40 %) were from different locations remote from the site where the horseshoe crabs were tagged and released. This study is on-going and notifications are still expected regarding the future location of the tagged animals.
Bookmarks Related papers MentionsView impact
Journal of Sustainability Science and Management, 2016
A morphometry study of 259 individuals of Tri-spine horseshoe crab Tachypleus tridentatus was car... more A morphometry study of 259 individuals of Tri-spine horseshoe crab Tachypleus tridentatus was carried out from April to October 2014 in two populations in Sabah, Malaysia, one in Tanjung Limau and another in Inderasabah. Two methods were used, i.e. visual search and gill netting. Both sites showed a higher number of males with 1.01:1 OSR (χ2=0.005, df=1, P>0.05) in Tanjung Limau, and 2.42:1 OSR (χ2=19.55, df=1, P<0.05) in Inderasabah. T. tridentatus collected from Tanjung Limau are larger than the population from Inderasabah. The prosomal width (PW) frequency for males ranged from 30-31 cm and 26-27 cm whereas for females ranged from 38-39 cm and 30-31 cm in Tanjung Limau and Inderasabah respectively. The prosomal width-weight relationship were W=0.0028 PW3.9273 and W=0.0125 PW3.5245, while the total length-weight relationship are W=0.0152 TL2.8465 and W=0.0202 TL2.7536 for Tanjung Limau and Inderasabah respectively. Two-way ANCOVA revealed a significant difference among PW-weight relationship in males and females in these two locations (F=4.74, df=1, P<0.05). It confirms that both populations demonstrate allometric growth (b≠3) with a higher increment of PW-weight as compared to TL-weight, which agrees with previous studies that reported similar traits. The differences in these morphometric parameters in both populations of T. tridentatus in this study suggest that they may derive from two discrete populations. The findings of this study are useful to estimate the size of adults and spawning individuals of T. tridentatus for better management of the population of this unique animal.
Bookmarks Related papers MentionsView impact
Cell & Developmental Biology , 2016
Due to limited availability of literature on the spawning activity of Malaysian horseshoe crab, T... more Due to limited availability of literature on the spawning activity of Malaysian horseshoe crab, Tachypleus gigas (Müller, 1785), the reproduction behaviour and biology of this arthropod remains poorly understood. Hence, an investigation was carried out from April-July to trail spawning horseshoe crab amplexus at Balok and Cherating, the only known T. gigas spawning grounds on the east coast of Peninsular Malaysia. Through visual tracking during daytime full moon spring tides, the release of air bubbles indicate nest digging by female crabs. While air bubble formation aggravated, flagged aluminium poles were carefully driven into the sediment to mark the nest. Out of the 13 spawning T. gigas amplexus tracked, only one pair was able to dig up to 12 nests and release up to 2,575 eggs within the 2.5 hour spawning period. The female crabs dug nests at the intertidal regions, ranging 1.3-43.2 m from the highest tide marking on the beach. Interestingly after spawning, the horseshoe crabs returned to high seas during the residing tides as amplexus because the male crabs remained clinging onto the female crab's opisthosoma. The incidence of recapturing a tagged female crab with different attached male crab at Cherating indicates this spawning ground as natal beach. In addition, the presence of 8 horseshoe crab amplexus at Balok compared to only 5 amplexus at Cherating highlight preferable beach settings for spawning and/or the presence of larger spawning crab assemblages at the former beach. Since only 13 spawning horseshoe crab pairs were witnessed at Balok and Cherating, identification of factors that alter beach sediment composition and water chemistry as well as gender-specific poaching and excessive boating activities should be regulated to restore wild T. gigas populations.
Bookmarks Related papers MentionsView impact
Books by Azwarfarid Manca
Penerbit UMT, 2016
This book is intended to reach as many audience as it could, designed in a simple and light manne... more This book is intended to reach as many audience as it could, designed in a simple and light manner with many images to make reading fun. It is meant to introduce horseshoe crabs to those who have never seen them, and to give additional information to those who know them. It is part of the effort of Horseshoe Crab Research Group of UMT to educate Malaysians on horseshoe crabs and the importance to conserve them.
Bookmarks Related papers MentionsView impact
Uploads
Papers by Azwarfarid Manca
Books by Azwarfarid Manca