Behavioural And Physiological Changes Of Blue Swimming Crab, Portunus Pelagicus At Different Culture Temperatures

Abstract

Inconsistent seed production and climate change cause problems for the crab culture industry. This study aimed to understand the effects of different water temperatures on the physiological conditions (survival, growth, molting, shell hardening, thermal tolerance, sexual differentiation and fatty acids compositions), behaviour, maturation and stress of blue swimming crab, Portunus pelagicus. In this study, P. pelagicus from first stage of instar were cultured at three different water temperatures (24 °C, 28°C and 32 ·C). Fatty acids composition in relation to maturation and stress were examined after certain physiological changes. Molting success as well as behaviour and hardening of the carapace were analyzed using a video recording with behavioural coding software and a novel hardness scale to obtain their physiological response. Meanwhile, thermal tolerance was calculated using a dynamic method and determination of stress on crab were carried out through histological examination of gills. The results indicate that the carapace width increased directly with temperature. Conversely, duration of the intermolt period was negatively correlated with temperature. The time of crabs' molting and carapace hardening were decreased with increasing temperature. The crab movement was positively correlated with temperature. Thermal tolerance increased directly with temperature. Monounsaturated Fatty Acids (MUFA) was the most abundant biochemical component, while Saturated Fatty Acids (SFA) represented a minor fraction of body compositions.