Growth rate and fatty acid composition of orange mud crab instars, Scylla olivacea, reared at different temperatures

Abstract

The objective of the present study was to examine the effect of different rearing temperatures on growth, survival, instar development, and fatty acid (FA) composition of orange mud crab instars, Scylla olivacea. The experiment was conducted at four different water temperatures of 24 °C, 28 °C, 32 °C and 36 °C using instar stage 1 (C1) in temperature-controlled recirculating rearing systems and lasted for 30 days. The study findings revealed that higher temperatures (≥32 °C) significantly reduced intermolt duration, whereby most crabs reached instar stages C6-C7, although 10.3% were still in the C2−C3 developmental stage. In addition, at temperature 36 °C all crabs were dead after three days of culture. Surprisingly, at constant temperature of 28 °C, total Polyunsaturated Fatty Acid were lower (0.52) compared to those at lower, 24 °C (0.71) and higher temperature of 32 °C (0.74). However, the direct effects of temperature on total fatty acids composition in crabs could not be distinguished from indirect effects of variable crab size and molt number. In conclusion, high temperature of 32 °C negatively affects instars growth and may induce molting, especially in S. olivacea. Keywords: Aquaculture, Crustacean, Fatty acids, Molt, Scylla olivacea, Temperature