温度和盐度对夜光藻种群密度增长的影响

Effects of temperature and salinity on increase in population density of alga Noctiluca scintillans

为了研究温度和盐度对夜光藻Noctiluca scintillans种群密度增长的影响,采用盐生杜氏藻Dunaliella salina为饵料(藻液密度为10.0×10^(4) cells/L),在室温条件下研究了5个温度水平(12、16、20、24、28℃)和7个盐度水平(18、22、26、30、34、38、42)对夜光藻种群密度增长的影响。结果表明:温度28℃时夜光藻的日增长率为负值,与其他4个温度组均有显著性差异(P<0.05),其种群密度一直降低,直至种群消失为零,16、20、24℃温度下平均日增长率均为0.18,种群最高密度变化在10.0×10^(3)~10.6×10^(3) ind./L,且无显著性差异(P>0.05),温度为12℃时种群密度持续增长,并达到最大值14.8×10^(3) ind./L;夜光藻密度与温度间的回归方程为y=-18.424x^(3)+1055x^(2)-19822x+132606(R^(2)=0.9994);夜光藻在盐度为18~42时均能存活,盐度为18~26时种群密度较高,尤其在盐度为26时密度最高可达25.8×10^(3) ind./L,盐度为30、34条件下次之,而在高盐度38、42时生长缓慢,最高密度值仅为3.8×10^(3)、3.0×10^(3) ind./L,二者间生长无显著性差异(P>0.05),但二者均与其他盐度组有显著性差异(P<0.05);夜光藻密度与盐度之间的回归方程为y=-0.0863x^(5)+12.641x^(4)-717.19x^(3)+19600x^(2)-257671x+10^(5)(R^(2)=0.8756)。研究表明,夜光藻在低温低盐度条件下生长较好,本研究结果可为预测夜光藻赤潮的发生及海洋生态环境保护提供一定的参考依据。

Alga Noctiluca scintillans was cultured and fed alga Dunaliella salina in a light incubator at temperature of 12,16,20,24,and 28℃and a salinity of 18,22,26,30,34,38,and 42 and then specific growth rate of the alga was determined to evaluate the effects of temperature and salinity on the increase in population density in alga N.scintillans under a laboratory condition.The results showed that there was negative value of growth rate of N.scintillans at 28℃,significantly different from those in the other four groups(P<0.05),and finally,the population density disappear to zero.The daily average growth rates of 0.18 was observed at 16,20 and 24℃,with the maximal population density(10.0×10^(3)-10.6×10^(3) ind./L),and without significant differences(P>0.05).The alga N.scintillans had continuous increase in population density,with the maximum of 14.8×10^(3) ind./L at 12℃,with the regression equation between temperature and the number of N.scintillans as y=-18.424x^(3)+1055x^(2)-19822x+132606(R^(2)=0.9994).N.scintillans was shown to be survive at salinity of 18-42,with higher population densities at salinity of 18-26,especially,the maximum of up to 25.8×10^(3) ind./L at a salinity of 26,followed by at a salinity of 30 and 34.However,poor growth was found in the alga exposed to a salinity of 38 and 42,with the maximal densities of only 3.8×10^(3) and 3.0×10^(3) ind./L,respectively.There was no significant difference in maximum population density between salinity 38 and salinity 42(P>0.05),significantly different from the other groups(P<0.05).The regression equation between salinity and the number of N.scintillans was expressed as y=-0.0863x^(5)+12.641x^(4)-717.19x^(3)+19600x^(2)-257671x+10^(5)(R^(2)=0.8756).The findings provide some theoretical reference with predicting the occurrence of red tide induced by N.scintillans and protecting marine ecological environment.