Eco-physiological Studies Of Nitrogen On The Growth Of Karenia Mikimotoi

The blooms of Karenia mikimotoi Hansen which caused mass mortalities offishes or invertebrates, resulted in serious damage to aquaculture industries. Thegrowth characteristics in different nitrogen sources, the uptake capability of severalnitrogens and the growth in starvation condition of Karenia mikimotoi have beenstudied. The species interaction with Prorocentrum donghaiense Lu have also beenstudied. The results are as follows:1. K. mikimotoi can utilize NH₄-N, NO₃-N, NO₂-N and urea as nitrogen sources,but it can not utilize glycin, alanine, threonine and tetramethylene-diaminehydrochloride. The optimum N/P ratio for NH₄-N, NO₃-N and urea was 32, but thevalue for NO₂-N was 100.2. When phosphate concentration was 0.65μmol/L, K. mikimotoi absorbed 40.2～51.6μmol/L nitrogen sources. The absorptivity of NH₄-N was the same as those ofNO₃-N, NO₂-N and urea, but the cell density was lower when cultured in NH₄-N.3. When nitrogen source were NO₃-N, NO₂-N and urea, the cell density can bekept in starvation condition, but not the NH₄-N. After stationary phase withadditional nutrition added, K. mikimotoi can grow well in urea when N/P ratio was16.4. The growth of K. mikimotoi was restrained when cultured with Prorocentrumdonghaiense and different inoculation of K. mikimotoi affected the growh of P.donghaiense. The cell-free filtrate of K. mikimotoi had allelopathic effects on thegrowth of P. donghaiense.