Seasonal variatons of digestive tract index, histology characteristics and enzyme activity of Holothuria edulis

To reveal the environmental regulation mechanism and aquaculture of tropical sea cucumber, and provide scientific basis for its artificial breeding, we studied the seasonal variations of physiological and biochemical conditions of Holothuria edulis, monitored the changes of the digestive tract index, histology characteristics and enzyme activities of H. edulis. Results show that the feeding state of H. edulis was relatively vigorous in spring and summer, and exhibited similar characteristics to Stichopus japonicus's aestivation in winter, which is characterized by decline of body mass, atrophy of digestive tract tissue, emergence of a large number of cavities due to cell apoptosis, decrease of the thickness of transverse folds and decrease of the density of columnar epithelium in the intestinal wall structure. The digestive enzymes and immune enzymes activities of the digestive tract tissues were the highest in March and June, respectively. In December, except for the alkaline phosphatase activity that regulates metabolism, all the others were at low values. Therefore, it is preliminarily judged that H. edulis have hibernation phenomenon.