Mass mortality of cultured ascidians Halocynthia roretzi associated with softening of the tunic and flagellate-like cells

Detection of the kinetoplastid Azumiobodo hoyamushi, the causative agent of soft tunic syndrome, in wild ascidians Halocynthia roretzi

“…In addition, the number of affected areas has increased annually (Kumagai et al 2010). This is probably due to dispersion of the flagellates from the torn tunics of diseased ascidians in local currents.…”

“…The disease has re-occurred annually at several farming sites following an initial outbreak, suggesting that the flagellate had become established in many ascidian farming areas in Japan (Kumagai et al 2010). In addition, the number of affected areas has increased annually (Kumagai et al 2010).…”

“…However, the present results indicated that the disease still persisted in the wild populations of ascidians after this event. Kumagai et al (2009) demonstrated that apparently healthy ascidians collected from cultured ascidian lots affected with the disease were asymptomatic carriers of the pathogen. Therefore, we collected both apparently healthy ascidians and dead individuals to improve our sensitivity of detection for the flagellate.…”

“…All samples were transported on ice to the MPFTI. The surveys were conducted between June and August 2010 and between July and August 2011, since the outbreak of the disease was most severe in summer (Kumagai et al 2010). The water depth at the sites ranged from 3 to 15 m.…”

“…Furthermore, the number of affected areas has increased since the disease was first detected (Kumagai et al 2010). This has raised concerns regarding the spread to wild populations, because some diseases of fish and shellfish that cause problems in the aquaculture industry have subsequently also infected wild populations.…”