The Eco-physiological Studies Of Phosphorus On The Growth Of Karenia Mikimotoi Hansen

Karenia mikimotoi Hansen caused frequently harmful algal blooms in the coast of areas ofChina in recent years. The present research studied the phosphorous eco-physiological charactersof K. mikimotoi in batch cultures and semicontinuous cultures.The utilization character of K. mikimotoi to phosphorous indicated that K. mikimotoi can useNaH₂PO₄·2H₂O, G-P, ATP. The algae prefer higher phosphorous concentration and lower N/Pratios.The absorption character of K. mikimotoi to phosphorous indicated that the K_s of K.mikimotoi to DIP is 0.26μM, which is lower than many other dinoflagellates. The affinity index(α) is 417.6, which is much higher than many other dinoflagellates. It is higher competitive abilityfor K. mikimotoi to absorb phosphate.The results of cellular growth kinetics research indicated thatμ_max of K. mikimotoi is 0.44 d^-1,which is within in the ordinary range of dinoflgellate growth rates. So K. mikimotoi is not a hamfulalgae which depend on growth strategy to bloom.The orthogonal experiment L₉(3³) of K. mikimotoi indicated that the optimal temperature,salinity and phosphorous for K. mikimotoi growth were 25℃, 25‰and 2.5μM respectively under100uE m^-2 s^-1 illumination.We can conclude that although the lowμ_max could not be triggered for K. mikimotoi blooming,the features that the utilization of several types of DIP and DOP, lower Ks and higherαmadeK. mikimotoi easier survival in low nutrition. The blooms occur when the environmentalfactors approach the best conditions.