摘要：This study was aimed to investigate the growth characteristics of living diet Platymonas subcordiformis foraquaculture animals and its harmful organism Oxyrrhis marina in co-culture systems to provide experimentalevidences for discussing their succession processes. The colour changes of culture media of P.subcordiformis and growth characteristics of O. marina and P. subcordiformis in co-culture were analysedby the combined methods of macro-observation, microscopic examination and microscopic counting. Theresults showed that with the decrease of the initial density of O. marina cell (0.65×10 4 cells mL -1 , 0.37×10 4cells mL -1 and 0.11×10 4 cells mL -1 in P. subcordiformis culture media), the time that the population of O.marina reached the stationary phase required longer, were 4d, 5d and 7d after inoculated by O. marina,respectively, and the death time of all cells of P. subcordiformis became longer, were 9d, 10d and 12d afterinoculated by O. marina, respectively. After inoculation 9d, pale pink appeared in upper layer of culturemedia of P. subcordiformis in flasks and the density of O. marina was 2.10×10 5 cells mL -1 . The results alsoindicated that the variation tendency of cell densities of O. marina and P. subcordiformis cultured in aquariumswere consistent with that in flasks basically, pink flocs appeared in upper layer of culture media of P.subcordiformis after inoculation 12d and the density of O. marina was 2.10×10 6 cells mL -1 . The experimentalresults showed that the feeding of O. marina on P. subcordiformis was affected by the initial concentrationof O. marina, and P. subcordiformis populations were evolved to O. marina populations during the 15 daysculture period, the colour of culture media appeared pale pink to pink depends on density of O. marina wasconfirmed, too. Also, the colour changes of P. subcordiformis culture media are indications of pollution by O.marina, which will be important for culture process of P. subcordiformis.
