Cross-transmission studies of Perkinsus karlssoni (Apicomplexa) from bay scallops Argopecten irradians to native Atlantic Canadian shellfish species

The potential for cross-transmission of Perkinsus karlssoni from bay scallops Argopecten irradians to various native Atlantic Canadian species of shellfish was investigated. Lateral proximal transmission was investigated whereby infected moribund bay scallops were maintained with uninfected individuals of other bivalve species in a recirculating artificial seawater system. There was no evidence, either histologically or by thioglycollate culture, to conclude that transmission of P. karlssoni had occurred over the 22 mo study period. Zoosporangial stages of P. karlssoni were observed in both the male and female gonads of the bay scallop, and the possibility of parasite release during spawning is discussed. Shellfish mortality over the study period was attributed to intolerance of the temperature and salinity ranges of the holding system.