Abstract
Present study was aimed to address the spawning and nesting behaviour of Malaysian horseshoe crab (Tachypleus gigas) in observed nesting grounds of East coast of Peninsular Malaysia during monsoonal period. Field sampling was carried out in every full and new moon days between September and December 2009 in Balok (Lat3°56.194’ N, Long103°22.608’ E) and Pekan (Lat3°36.181’ N, Long103°23.946’ E) nesting grounds. A total of 26 nests were found throughout the sampling period (Balok = 4 nests [~15%]; Pekan = 22 nests [~85%]) with higher percentage nesting was noted in November (N = 11 nests [~50%]) in Pekan. No nests were found in Balok station in all sampling months except during September (4 nests). It was also noted that the horseshoe crab preferred nesting during full moon time compared to new moon period. Mean depth × width of the T.gigas nests were 19.96±5.6×10.72±2.1cm. Number of eggs and larval counting in each nest were also recorded together with hydrographic and sedimentological parameters of the nesting grounds. This study clearly showed negative influence of monsoonal cycle on the nest preference and spawning behaviour of T.gigas. Long term monitoring studies would enable us to understand the number of shore reaching horseshoe crabs which is an essential source for the wild population.
Highlights
An important biomedical application to detect/quantify bacterial endotoxin using a specialized cell compound from horseshoe crab blood lead to greater exploitation of their natural population worldwide (John et al, 2011)
The sampling was carried out in every full and new moon days at two different stations Balok and Pekan (East coast of Peninsular Malaysia) which were observed to be the nesting grounds of horseshoe crabs (Zaleha et al, 2010) (Figure 1)
A total of 26 nests were found in Balok and Pekan nesting grounds during the monsoon period (Sep-Dec) comprising of 22 nests in Pekan (84.6%) and 4 nests in Balok (15.39%)
Summary
An important biomedical application to detect/quantify bacterial endotoxin (lipopolysaccharide) using a specialized cell compound from horseshoe crab blood lead to greater exploitation of their natural population worldwide (John et al, 2011). The ecophysiological status of Malaysian horseshoe crab (Tachypleus gigas) is still limited (Akbar John et al, 2011 and 2012a). It is well documented that the nesting and spawning behaviour of horseshoe crab is directly related to the nature of nesting grounds (Botton et al, 1988). Horseshoe crabs migrates towards the nesting beaches at every full and new moon days (especially at night time) to spawn. During this migration, the male crabs are tenaciously attached to the female opisthosoma using modified, claw-like pedipalps (Brockmann and Penn, 1992). The development of nested eggs in to trilobite larvae is greatly influenced by external environmental conditions
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