Growth interactions between raphidophytes chattonella antiqua and Heterosigma akashiwo

We investigated growth interactions between the raphidophytes Chattonella antiqua (Hada) Ono and Heterosigma akashiwo (Hada) Hada ex Hara et Chihara using bi-algal cultures under axenic conditions. The growth of C. antiqua and H. akashiwo each tended to be strongly suppressed when the other species reached early stationary phase. A mathematical model was used to simulate the growth interactions of C. antiqua and H. akashiwo in bi-algal cultures. The model showed that C. antiqua outcompetes H. akashiwo over time in bi-algal cultures under all experimental conditions. Furthermore, despite re-enrichment with nutrients, the filtrate from dense cultures of C. antiqua reduced the maximum growth rate of H. akashiwo and filtrate from dense cultures of H. akashiwo reduced both the maximum growth rate and maximum yield of C. antiqua.