Acceleration of the Occurrence of Vibriosis in Ayu <i>Plecoglossus altivelis</i> by Cyanobacterial Picoplankton <i>Synechococcus</i> 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.

Physiological State of Vibrio anguillarum, a Fish Pathogen, under Starved and Low-Osmotic Environments.

“…However, the VBNC cells of L. pneumophila under conditions of starvation, can be resuscitated by a coculture with amoeba, Acanthamoeba castellanii, an intermediate host 22) . We have tried co-cultures with a picoplankton, Synechococcus sp., which was deposited on the bottom of Lake Biwa, Japan 5) , and enhanced the pathogenicity and growth of V. anguillarum 23) . However, this treatment did not work (data not shown).…”