| Raphidophyte Heterosigma akashiwo and Chattonella marina are two fish-killing red-tide species, which widely distribute in the world and have caused great economic loss in many countries such as Japan, Canada, Australia and China. Effects of N, P, and salinity on the growth characteristics and two antioxidant enzymes (Superoxide Dismutase, SOD and Catalase, CAT) activities of H. akashiwo and C. marina were investigated in the present study.Results indicated that macroelement N and P were crucial elements for the growth of both species. H. akashiwo and C. marina cells grew faster in the media with supplementary N and P. In the media without N and P, growth curve could not be observed. The growth of H. akashiwo was insignificantly different among different N/P ratios (5,15,45) and salinities (15,25,35) , and different N/P ratios (5,15,45) still had no remarkable effects on the growth of C. marina, however, higher salinity (35) could inhibit the growth of C. marina. The optimal growth condition of H. akashiwo was N (225mg/L), P (5mg/L), salinity (15) and N/P (45/1). The optimal growth condition of C. marina was N (75mg/L), P (15mg/L), salinity (15) and N/P (5/1). Our results implies that eutrophication of coastal water is one of the critical factors for triggering H. akashiwo and C. marina.Under the stress of N or P deficiency, H. akashiwo and C. marina were able to maintain higher activity of SOD and CAT. The effects of P on SOD and CAT activity were more significant than that of N and salinity. SOD and CAT activity of both species maintained lower level in the media with supplementary N and P, and decreased during the period of experiment. Under higher salinity (35) stress, SOD and CAT activity of C. marina higher than that of lower salinity (15, 25), while higher salinity (35) had no remarkable effects on SOD and CAT activity of H. akashiwo. N/P ratio had no remarkable effects on SOD and CAT activity of both species.
|
PDF Full Text Request