不同营养盐浓度对6种海洋微藻群落演替的影响

摘要

在不同的营养盐总体浓度（2f、f/2、f/8培养基）、不同的氮质量浓度（299．2、74．8、18．7 mg/L ）、不同的磷质量浓度（17．6、4．4、1．1mg/L）和不同的铁质量浓度（15．6、3．9、0．98mg/L）下，对三角褐指藻、杜氏盐藻、米氏凯伦藻、小新月菱形藻、青岛大扁藻和前沟藻进行混合培养试验，采用恒定最终密度法研究营养盐浓度对6种海洋微藻群落演替的影响。试验结果表明，在高营养盐浓度（2f培养基）时绿藻占优势，占总细胞密度的75．6％，随着营养盐浓度的降低，硅藻竞争力上升，在低营养盐浓度（f/8培养基）时，硅藻占总细胞密度的57．0％。在氮高质量浓度（299．2 m g/L ）时，硅藻占优势，占总细胞密度的55．7％，随着氮质量浓度降低，硅藻竞争力下降；在氮低质量浓度（18．7 mg/L ）时，硅藻和绿藻比例分别是46．6％和48．3％。在磷高质量浓度（17．6 m g/L ）下，绿藻占优势，占总细胞密度的63．6％，随着磷质量浓度降低，硅藻逐渐占优势；在磷低质量浓度（1．1 mg/L ）时，硅藻细胞比例为54．3％。硅藻在铁高质量浓度（15．6mg/L）和低质量浓度（0．98mg/L）时，都能占有一定的竞争优势，分别占总细胞密度的71．5％和52．1％。在所有的处理组中，甲藻的生长均受到抑制，只占总细胞密度的很小一部分。%In this paper ,six marine microalga species(Phaeodactylum tricornutum ,Nitzschiaclosterium f .minutissima , Dunaliella salina , Platymonas helgolandica var .tsingtaoensi , K arenia mikimotoi and Amphidinium carterae)were cultured together under different nutrient concentrations (2f medium ,f/2 medium ,and f/8 medium) ,different N concentrations (299 .2 mg/L ,74 .8 mg/L ,and 18 .7 mg/L) , different P concentrations (17 .6 mg/L ,4 .4 mg/L ,and 1 .1 mg/L ) and different Fe concentrations (15 .6 mg/L ,3 .9 mg/L ,and 0 .98 mg/L ) to evaluate the effects of nutrient concentrations on the community succession in the six species of microalgae .The results showed that green algae were the predominant in high nutrient concentration (2f medium) and accounted for 75 .6% of the total cell density .The diatoms had strong competitiveness with the decreasing nutrient concentrations ,accounting for 57 .0% of the total cell density in f/8 medium .The predominant diatoms were observed at high N concentration (299 .2 mg/L) ,representing 55 .7% of the total cell density .The competitiveness of diatoms was found to be declined with the decreasing N concentrations .In low N concentration (18 .7 mg/L) ,46 .6% of diatoms and 48 .3%of green algae were found and green algae were the predominant species in high P concentration (17 .6 mg/L) ,accounting for 63 .6% of the total cell density ,while the diatoms became dominant with the decline in P concentration ,accounting for 54 .3% of the total cell density in low P concentration (1 .1 mg/L ) . Diatoms had competitive advantage in high (15 .6 mg/L ) and low (0 .98 mg/L ) Fe concentrations , accounting for 71 .5% and 52 .1% of the total cell densities ,respectively .The dinoflagellates were inhibited in grow th with small proportion in the total cell densities in all treatments .