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Effect of water salinity using limb autotomy technique on molting cycle of
orange mud crab, Scylla olivacea (HERBST, 1796) in captivity
Lawrencia Casey Gamburud
Supervisor: Prof Dr Mhd Ikhwanuddin Abdullah
Bachelor of Science in Agrotechnology (Aquaculture)
School of Fisheries and Aquaculture Sciences
Complete understanding on how molting cycle of portunid crabs can be influenced by
environmental conditions such as water salinity is crucial in production of soft-shell
crab. Soft shell crabs have high commercial value, however demand in Malaysia could
not yet been fulfilled due to lack of important knowledges regarding their production.
Previous studies reported that water salinity plays important roles in orange mud crab,
Scylla olivacea growth, survival, distribution, ovarian maturation, mating and
physiology, however, yet no specific study regarding molting have been done.
Therefore, present study aimed to determine the effects of water salinity using limb
autotomy technique on molting duration, survival and increment sizes of body weight
(BW) and carapace width (CW) of female S. olivacea. 180 samples of immature female
S. olivacea were obtained from Kuala Kedah, Kedah, Peninsula Malaysia (80.0-130.0
g BW and 7.0-9.0 cm CW). Crabs were acclimatized and were introduced to limb
autotomy and proceed with rearing in three different treatments (Treatment 1 (T1) at
10 ppt, Treatment 2 (T2) 20 ppt and Treatment 3 (T3) at 30 ppt) respectively. Results
show that T2 recorded the shortest molting duration with an average 22.2 days,
followed by T3 with 22.3 days and T1 with 23 days. As for BW and CW increment,
result shows that T3 has the heaviest BW compared to the T1 and T2, yet T1 and T3
showed an increase in CW compared to T3 respectively. As for survivability, T1
recorded the highest average survival percentage of S. olivacea with 96.67%, followed
by T2 with 76.67% and T3 with 70%. The findings of the present study also suggest
that, apart from the limb autotomy technique that helps inducing the molting process,
water salinity do play major role in shortening the molting duration of S. olivacea.
Therefore, the present study highly recommended that 20 ppt as the suitable water
salinity treatment to produce soft-shell crab in captivity.
490 | UMT UNDERGRADUATE RESEARCH DAY 2018