Effects of Different Phosphorus Source on the Growth and Interspecific Competition in 3 Marine Microalgal Species

LIANG Ying; LI Zebang; LIU Chunqiang; TIAN Chuanyuan; HUANG Xulin

Abstract：The present study was conducted to investigate the effects of different phosphorus source (sodium dihydrogen phosphate,sodium glycero phosphate and adenosine triphosphate disodium) on the growth and interspecific competition in three marine microalgal species:Dunaliella salina,Phaeodactylum tricornutum and Karenia mikinotoi,which were cultured in monoculture and mixed culture,respectively.The results indicated that in the monoculture,all the three microalgal species could use the three different forms of phosphorus source for growth.The highest average specific growth rate (0.614/d) was recorded by P.tricornutum in sodium dihydrogen phosphate treatment.In sodium glycero phosphate treatment,the utilization efficiency of phosphate in D.salina and K.mikinotoi were significantly higher than that in the other two phosphorus source treatments (P＜0.05),in which the average specific growth rate reached 0.531/d and 0.356/d,respectively.When the three microalgal species were in mixed culture,the percentage of the total cell density of D.salina in sodium dihydrogen phosphate treatment was significantly higher than those observed under the other two phosphorus source treatments and reached to 42.7 ％.For P.tricornutum,the percentages of the total cell densities were 59.8％ and 63.5％,the average specific growth rates were 0.516/d and 0.534/d in sodium glycero phosphate treatment and adenosine triphosphate disodium treatment,respectively,which were higher than those in sodium dihydrogen phosphate treatment.Whereas,the average specific growth rate,the final cell density and the percentage of the total cell density of K.mikinotoi under three different phosphorus sources were all significantly lower than those of other two microalgae.The average specific growth rate (0.236/d) in sodium glycero phosphate treatment was the lowest in all treatments,and the percentage of the total cell density was only 4.89％.The results also showed that all the P.tricornutum were the dominant species in three phosphorus sources in mixed culture.