Browsing by Author "Muhd Fawwaz Afham Mohd Sofa"

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    Trailing the Spawning Horseshoe Crab Tachypleus gigas at Designated Natal Beaches on the East Coast of Peninsular Malaysia
    (Cell and Developmental Biology, 2016) Azwarfarid Manca; Faridah Mohamad; Bryan Raveen Nelson; Muhd Fawwaz Afham Mohd Sofa; Amirul Asyraf Alia’m; Noraznawati Ismail
    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.
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    Width-Weight And Length-Weight Relationships Of The Tri-Spine Horseshoe Crab, Tachypleus Tridentatus (Leach 1819) From Two Populations In Sabah, Malaysia: Implications For Population Management
    (Journal of Sustainability Science and Management, 2016-06) Faridah Mohamad; Azwarfarid Manca; Amirrudin Ahmad; Muhd Fawwaz Afham Mohd Sofa; Amirul Asyraf Alia’m; Noraznawati Ismail
    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 lengthweight 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.