Acceleration of the Occurrence of Vibriosis in Ayu Plecoglossus altivelis by Cyanobacterial Picoplankton Synechococcus sp.

Abstract

Vibriosis in ayu Plecoglossus altivelis has occurred in Lake Biwa, Japan, along with the blooming of cyanobacterial picoplankton. To search the factors accelerating the occurrence of vibriosis in ayu, the effect of picoplankton on the mortality of ayu was investigated. Pretreatment of ayu with Synechococcus sp. clone P before infection accelerated the occurrence of vibriosis in experimental infections. Moreover, a higher number of Listonella anguillara adhered to the skin which was taken from fish reared with clone P. These findings suggest that the acceleration of the occurrence of vibriosis by clone P is caused by facilitating the attachment of L. anguillara to the skin.