Prevention and treatment of plate disease of cultured sea cucumbers

This disease, also known as "skateboard disease", "detachment disease" and "disintegration disease", often occurs when the bottle-shaped larva is metamorphosed to the five-tentacle larva and the juvenile ginseng after the larva is attached to the plate. It is the most serious and common epidemic disease in the later stage of sea cucumber seedling cultivation. The disease is highly contagious and occurs quickly, and the mortality rate within a few days can be close to 100%.

The main symptoms were as follows: the attached larvae contracted and did not stretch, the tentacles contracted, the vitality decreased, the adhesion was poor, and gradually lost the ability to adhere to the attachment base and sank to the bottom of the pool. Under the light microscope, brown 'rust' spots and dirt appeared on the epidermis of the diseased larvae, and some of the diseased juvenile ginseng bodies were surrounded by a transparent film, and the skin gradually festered until disintegrated and the bone fragments were scattered. Microscopic examination showed a large number of bone fragments at the bottom of the pool.

Analysis and study show that there are three strains of Gram-negative bacteria can cause this disease, with the diversity and complexity of pathogens. A Vibrio strain has been identified as one of the pathogenic bacteria. In terms of prevention and control measures: on the one hand, the method of secondary sand filtration or ultraviolet disinfection should be adopted, and the residual bait, feces and organic matter should be removed in time, and the pool should be poured in time to reduce the number of bacteria in the culture water as much as possible; on the other hand, attention should be paid to the quality and quantity of bait, especially through disinfection treatment to ensure that bait such as sea mud and sargassum do not carry important pathogens. In addition, regular microscopic examination should be conducted to observe the feeding, activity and health status of the larvae. When the disease was found, quinolone antibiotics were sprinkled in the pool and treated with medicine bath and oral administration at the same time.