EFFECT OF WATER SALINITY ON EXTERNAL MORPHOLOGY OF OVARIAN MATURATION STAGES OF ORANGE MUD CRAB, Scylla olivacea (HERBST, 1796) IN CAPTIVITY Amin-Safwan, A. 1*, Muhd-Farouk, H. 1, Nadirah, M. 2, & Ikhwanuddin, M. 1 1Institute Tropical of Aquaculture , 2School of Fisheries and Aquaculture Sciences, Universiti Malaysia Terengganu, 21030 Kuala Terengganu, Terengganu, MALAYSIA Email:
[email protected]
ABSTRACT This study was conducted to observed the effect of water salinity on the external morphology of the ovarian maturation of female orange mud crab, Scylla olivacea in captivity. There were three treatments used, Treatment 1 (T1) with 10ppt, Treatment 2 (T2) with 20ppt and Treatment 3 (T3) with 30ppt water salinity. The cultural period was 60 days and for every 15 days, 5 crabs from each treatments will be randomly chosen for dissection to observe the ovaries colouration and Gonad Somatic Index (GSI) calculation. On Day 0 (control), mean GSI was 0.19±0.04% and in Stage 1 ovarian colouration. By Day 15, mean GSI for T1 was 1.37±0.04%, T2 was 0.16±0.03% and T3 was 0.26±0.09%. All treatments showed Stage 1 ovaries. By Day 30, mean GSI for T1 was 1.12±0.82%, T2 was 6.86±2.74% and T3 was 0.34±0.04%. Day 30 showed that there were present of Stage 1, Stage 2 and Stage 3 ovarian maturation based on external morphology. By Day 45, mean GSI for T1 was 4.17±0.29%, T2 was 7.68±1.40% and T3 was 0.36±0.03%. Day 45 showed that there were presents of Stage 1, Stage 3 and even Stage 4 ovarian maturation based on external morphology. By Day 60, mean GSI for T1 was 4.86±1.70 %, T2 was 14.10±5.50% and T3 was 0.45±0.17%. Day 60 showed that there were present of Stage 1, Stage 3 and mostly were Stage 4 ovarian maturation based on ovaries colour. T2 produced the highest number of Stage 4 ovaries and mean GSI, followed by T1 and lastly T3. Therefore, water salinity does affected the ovarian maturation of female S. olivacea in captivity.
INTRODUCTION
METHODOLOGY Limb autotomized technique
Immature crabs
A
B
Ovary
Ovary
D
C
Ovary
Ovary
Figure 1. Ovary Stages of S. olivacea. (A) Stage 1 ovary (whitish to creamy white), (B) Stage 2 ovary (yellow), (C) Stage 3 ovary (orange) and (D) Stage 4 ovary (dark orange). 25.00
Mean Gonadal Somatic Index (%)
Tasty and high quality flesh
Highly market demand
Dissection
RESULTS & DISCUSSION
Hypothesis: Effective water salinity will speed up ovarian maturation of S. olivacea in captivity. Problem statement: The reason of slow growing during cultured in captivity may due to lack of information regarding water salinity as natural habitat involved tidal situation. Therefore, the most suitable and effective water salinity is important for ovarian maturation.
High meat yield
Body weight measurement
Newly matured crabs were cultured in 3 different salinity
High growth rate
Orange mud crab, Scylla olivacea • Known as Ketam Sepit Merah (local name). • Most abundance species in mangrove areas in Malaysia (Ikhwanuddin et al., 2010a). • High tolerance range of water salinity (Chen & Chia, 1997; Davenport & Wong, 1987; Nurdiani & Zeng, 2007).
20.00 15.00
10ppt 20ppt 30ppt
10.00 5.00 0.00 Day 0
Day 15
Day 30 Day 45 Day 60 Culture period Figure 2. Mean Gonad Somatic Index for each treatment by days
Salinity: • Measurement of all salts that dissolved in water. • Normally measured in part per thousand (ppt). • The average ocean salinity is 35ppt and average river water salinity is 0.5ppt • It was observed in this present study that the colour of Stage 1 ovaries which is or less. immature is translucent to yellow and become orange and reddish orange in mature ovaries • Based on Muhd-Farouk et al. (2016), Muhd-farouk et al. (2014) and Ikhwanuddin et al. (2014), ovarian maturation of S. olivacea was classified to have four stages (Stage • This present study have proved that salinity does affected the ovarian 1-4) based on their external morphological characteristics and histological maturation of S. olivacea. assessment characteristics. • The best treatment is T2 (20 ppt) as it produced the highest mean GSI • The highest GSI recorded in this present study was 14.10±5.50% on Day 60 T2, while and the most Stage 4 ovaries compared to other treatments. the lowest GSI recorded was 0.16±0.03% on Day 15 T2. • Even though external morphology such as ovarian colouration and GSI • Previous study by Ikhwanuddin et al. (2011) and Teshima and Kanazawa (1983), can be taken as factors to determine the stages of ovarian maturation, factors such as diets, salinity and temperature does influenced the reproductive histological assessment need to be taken as it give more accurate results biology of crabs. (Madlen et al., 2012).
CONCLUSION
REFERENCES
ACKNOWLEDGMENT This study had been funded by NRGS research grant (Vot. No. 53131). Many thanks to my supervisor, Assoc. Prof. Dr. Mhd. Ikhwanuddin bin Abdullah, my co-supervisor, Dr. Nadirah binti Musa, laboratory mates especially Muhd Farouk bin Harman, Aaqillah Amr binti Mohd Amran and Ros Suhaida binti Razali, laboratory officers and Hatchery staffs from AKUATROP, UMT for their assistance and guidance in order to complete this study.
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Ikhwanuddin, M, J. Nur-Atika, A.B. Abol-Munafi and H. Muhd-Farouk. (2014). Reproductive biology on the gonad of female orange mud crab, Scylla olivacea (Herbst, 1796) from the west coastal water of peninsular Malaysia. Asian Journal of Cell Biology, 9: 14-22. Madlen M. H., Khadiga M. S., and Montaser M.S.H. (2012). Morphological and histological studies on the embryonic development of the freshwater prawn, Macrobrachium rosenbergii (Crustacea, Decapoda). The Journal of Basic & Applied Zoology. 65(3), 157-165. Muhd-Farouk, H., Jasmani, S., and Ikhwanuddin. M. (2016). Effect of vertebrate steroid hormones on the ovarian maturation stages of orange mud crab, Scylla olivacea (Herbst, 1796). Aquaculture, 451, 78–86.
