The effect of temperature fluctuation on the growth and polysaccharide composition of phytoplankton

Abstract

以铜绿微囊藻、蛋白核小球藻及梅尼小环藻为研究对象,分析了春季藻类演替期间主要门类藻对温度波动的响应,实验在恒温(20℃)和昼夜波动(20±5℃)2种温度模式下测定了3种藻的生长和不同形态多糖含量的变化.结果表明,蛋白核小球藻的生长曲线在不同处理条件下没有显著性差异,铜绿微囊藻和梅尼小环藻的生长曲线在波动温度组显著低于恒定温度组,而且温度波动对梅尼小环藻的生长抑制明显强于铜绿微囊藻.随着实验的进行,3种藻在2个温度处理组中的生长速率逐渐趋近,无显著差异,但是在实验中段3种藻的生长速率对2个温度处理的响应差异显著,其中温度波动对蛋白核小球藻的生长速率起到了显著的抑制作用,对梅尼小环藻起到短暂的显著抑制作用,而对铜绿微囊藻的生长速率无显著性影响,表明铜绿微囊藻对短期(3~6 d)的温度波动表现出较强的适应能力.铜绿微囊藻的游离多糖含量在温度波动条件下显著增加,而固着多糖和总多糖的含量显著减少;蛋白核小球藻和梅尼小环藻多糖的含量没有显著性变化,表明温度波动可能不利于铜绿微囊藻固着多糖的积累.因此,相对短期的温度波动有利于铜绿微囊藻生长优势的确立与维持,而相对长期的温度波动可能会通过影响铜绿微囊藻固着多糖的积累而影响其生长优势的维持.;To investigate the influence of fluctuating temperature on the growth and polysaccharide composition of Microcystis aeruginosa, Chlorella pyrenoidosa and Cyclotella meneghiniana were cultured under two temperature patterns:diurnal fluctuating temperature of 20 ± 5℃ and constant temperature of 20℃. In the present experiment we determined the growth curve, growth rate and the content of different polysaccharide compositions. Results show that growth curves of C. pyrenoidosa under two temperature patterns had no significant differences, while those for both M. aeruginosa and C. meneghiniana under fluctuating temperature were significantly inhibited, and the latter suffered the prominently stronger inhibition. As the experiment proceeded, the growth rates for the three algae under the two temperature treatments gradually tend to be no obvious differences, but their responses to the two treatments had significant differences in the middle of experiment. Therefore, temperature fluctuation posed a remarkable inhibitory effect and a short significant inhibitory impact, respectively, to the growth rates of C. pyrenoidosa and C. meneghiniana, whereas it had no obvious effect on M. aeruginosa, revealing that M. aeruginosa showed a stronger ability to adapt to the short term (3-6 d) temperature fluctuation. As for polysaccharide, temperature fluctuation markedly promoted the increase of the soluble extracellular polysaccharide content and decreased the bound polysaccharide content and total polysaccharide content of M. aeruginosa, indicating that temperature fluctuation may not facilitate the bound polysaccharide accumulation of M. aeruginosa. Therefore, relative short-time temperature fluctuation will be in favor of establishing and maintaining M. aeruginosa dominance, but relative long-term temperature fluctuation may benefit C. pyrenoidosa dominance more than M. aeruginosa due to decreased bound polysaccharides of M. aeruginosa.