Chemoattractability of amino acid glycine, fish oil and star anise oil in smooth marron (Cherax cainii Austin & Ryan, 2002)

Abstract

The chemoattractability of three attractants, the free amino acid glycine, fish oil and star anise oil, Illicium verum Hook f., in the freshwater crayfish, smooth marron, Cherax cainii Austin & Ryan, 2002, was assessed by measuring their excitatory capacity and time spent in pre- and post- attractant phase. Marron were observed individually for 5 min in 10 L glass aquaria before and 5 min after the addition of filtered freshwater as a control, glycine high (10-4 mol L-1), glycine low (10-6 mol L-1), fish oil and anise oil. Attractants were added directly to the aquarium water, and the marron excitatory capacity was recorded. Frequency was recorded of the excitatory behaviours: antennae wave, antennule wave, pereopod wave, maxilliped wave, cheliped wave, and cheliped grasp. Time spent in pre- and post- attractant phase activities; resting, walking, climbing wall, and searching for food, were also recorded. The excitatory response of C. cainii was shown as an increase in pereopod sweeping and probing. Overall, the frequency of antennule wave, leg wave and maxilliped wave increased during the post-attractant phase (p < 0.05). Marron spent more time searching for food with glycine high, anise oil and fish oil than with filtered freshwater. Resting time was higher in marron given filtered freshwater than those given glycine high. The results of this study show that glycine, fish oil, and anise oil are effective chemoattractants of marron, however, their suitability as feeding incitants still needs to be assessed further.