扰动方式对太湖藻类胞外多糖浓度的影响

Effect of Disturbance on the Concentrations of Algal Extracellular Polysaccharide in Lake Taihu

频繁的风浪扰动是影响大型浅水湖泊生态系统最重要环境因素之一.为了解风浪扰动对富营养化大型浅水湖泊——太湖蓝藻EPS (extracellular polysaccharide,胞外多糖)的影响,试验设置了对照组(不扰动)、间歇扰动组和持续扰动组3种处理组,研究扰动方式及理化因子对蓝藻EPS的影响.结果表明:①第1~7天,3种处理组之间的ρ(EPS)、ρ(sEPS)(soluble extracellular polysaccharide,溶解性胞外多糖)和ρ(bEPS)(bound extracellular polysaccharide,固着性胞外多糖)差异均不显著(P>0.05);第10~19天,对照组的ρ(EPS)、ρ(sEPS)和ρ(bEPS)均显著低于间歇扰动组和持续扰动组(P<0.05);第19天,持续扰动组的ρ(sEPS)和ρ(bEPS)均显著高于间歇扰动组(P<0.05).②3种处理组的ρ(EPS)及单位藻细胞EPS含量与ρ(TDN)(TDN为溶解性总氮)及ρ(TDP)(TDP为溶解性总磷)均呈显著负相关;3种处理组的ρ(EPS)与ρ(SS)(SS为悬浮颗粒物)均呈显著正相关;此外,两个扰动组的ρ(EPS)均与藻细胞密度呈显著负相关.研究显示,扰动在一定程度上促进了蓝藻EPS的分泌.

Frequent disturbance from waves caused by wind is one of the most important environmental factors affecting the ecosystems of large shallow lakes. To explore the effects of disturbance on algal EPS (extracellular polysaccharide) in the large,shallow,eutrophic Lake Taihu,we carried out an experiment with three treatments,including control (undisturbed),intermittent disturbance and continuous disturbance. The results showed that: (1) There was no significant difference in ρ (EPS), ρ (sEPS) (soluble extracellular polysaccharides) and ρ (bEPS) (bound extracellular polysaccharides) among the three treatments over 1-7 days (P>0. 05). Between 10 and 19 days,the ρ (EPS),ρ (sEPS) and ρ (bEPS) of the control group were significantly lower than those of in the intermittent disturbance group and the continuous disturbance group (P < 0. 05). On the 19th day,the ρ (sEPS) and ρ (bEPS) of the continuous disturbance group were significantly higher than those of the intermittent disturbance group (P<0. 05). (2) The ρ (EPS) and EPS at unit algal cells of the three treatments were significantly negatively correlated with ρ (TDN) and ρ (TDP);the ρ (EPS) of the three treatments were significantly positively correlated with ρ (SS);in addition,the ρ (EPS) of the two disturbance groups were significantly negatively correlated with algal cell density. Our results show that disturbance can promote the secretion efficiency of EPS by algae.