清洁疏浚物对2种海洋微藻种间竞争的影响

采用实验生态学方法,研究了不同起始密度下悬浮清洁疏浚物对中肋骨条藻Skeletonema costatum和赤潮异弯藻Heterosigma akashiwo生长的影响。研究结果表明,在实验室单培养条件下,清洁疏浚物培养液中,起始密度不同,微藻生长状况明显不同。起始密度为0.2×10⁴ cells·mL^-1时,进入指数生长期和静止期的时间延长,但生长所达到的最大细胞密度较高;起始密度为0.8×10⁴ cells·mL^-1时,进入指数生长期和静止期的时间缩短,但生长所达到的种群最大密度较低。混合培养条件下,清洁疏浚物培养液中,起始密度不同,导致了微藻种间竞争关系的变化,中肋骨条藻与赤潮异弯藻具有明显的种间竞争,赤潮异弯藻是竞争的优胜者,中肋骨条藻受到赤潮异弯藻的抑制,整个实验周期内细胞密度下降都非常明显,细胞密度明显低于单培养时的细胞密度,而赤潮异弯藻细胞密度并没有明显的减少。在3种不同质量浓度组清洁疏浚物培养液中,质量浓度最高的1 000 mg·L^-1培养液中藻细胞密度显著低于100 和500 mg·L^-1质量浓度组,而100 mg·L^-1培养液中藻细胞密度最高,说明清洁疏浚物质量浓度越高,对海洋微藻抑制影响越为明显,质量浓度越低,影响越小。

Effects of cleaning dredged materials on the interspecific competition between two species of microalgae

The effects of cleaning dredged materials on the growth of two marine microalgae species with different initial cell density:Skeletonema costatum and Heterosigma akashiwo, were investigated by using the measures of experimental ecology. The results show that at the unialgal culture medium of cleaning dredged materials in laboratory, the different initial cell density has apparent effects on the growth of microalgae. At the initial cell density of 0.2×10⁴ cells·mL^-1, the time of entering exponential phase and stationary phase can be extended, and reaching the maximum cell density is higher; at the initial cell density of 0.8×10⁴ cells·mL^-1, the time of entering exponential phase and stationary phase could be shortened, and reaching the maximum cell density is reduced. For the mixed cleaning dredged materials culture medium, the different initial cell density has apparent effects on the relation of interspecific competition between two species of microalgae. There is obvious interspecific competition between S. costatum and H. akashiwo. H. akashiwo has predominance in this competition, and S. costatum suffers from H. Akashiwo inhibition, within the entire experimental period, cell density reduces very significantly and is lower than that in the unialgal culture, while H. akashiwo cell density is not significantly reduced. Among these three different medium concentrations of cleaning dredged materials, the cell density in the highest culture medium concentrations of 1 000 mg·L^-1 is significantly lower than those in 100 mg·L^-1 and 500 mg·L^-1 culture medium, and the cell density is the highest in 100 mg·L^-1 culture medium. This indicates that the greater of clean dredged materials concentrations, the greater effects on the growth of microalgae, while the lower of clean dredged materials concentrations, the smaller effects on the growth of microalgae.