A preliminary study on food consumption, preference and day-night predatory difference of Asterias amurensis on Scapharca broughtonii

Abstract

In order to study the food consumption, preference and day-night predatory difference of Asterias amurensis on Scapharca broughtonii, the experiments were carried out at the temperatures ranging from 16 ℃ to 20 ℃, salinity of 28.2 ± 2.1, dissolved oxygen of 7.5±0.7 mg/L and pH of 8.0 ± 0.3.The results provided basic data for promoting steady and healthy development of the multiplication and cultivation of S. broughtonii. The results of food consumption suggested that the food intake of starfish increased with the density of S. broughtonii at all conditions. The food consumption of starfish in different sizes on S. broughtonii in the same size had no significant difference (p>0.05), but it was significantly different among S. broughtonii in different sizes. The starfish had the highest feeding rate on the smallest S. broughtonii. Our findings also verified the positive relation between the weight of food intake of starfish in different sizes on the density and size of S. broughtonii. The feeding rhythm of starfish on S. broughtonii in different sizes showed a certain day-night difference, higher at night than in the day. The maximum food consumption occurred when the size of S. broughtonii became larger. The results showed that 30 ind/m2 was the suitable sea bottom sowing density for S. broughtonii. Our data indicated that the ability to avoid predators and rivals increased as the shell length rose. Based on prey selectivity, bivalves that have a lower commercial value may be used to clear away A. amurensis.