Effect of flow rate on environmental variables and phytoplankton dynamics： results from field enclosures

• Published in: Chinese journal of oceanology and limnology Vol. 33; no. 2; pp. 430 - 438
• Main Author: 张海平 陈瑞弘 李飞鹏 陈玲
• Format: Journal Article
• Language: English
• Published: Heidelberg Springer-Verlag 01.03.2015; Science Press; Springer Nature B.V
• Subjects: Algae; algal blooms; Aquatic plants; Artificial lakes; asexual reproduction; Biology; Biomass; Chlorophyll; Chlorophylls; Critical flow; Cyanobacteria; Dissolved oxygen; Earth and Environmental Science; Earth Sciences; Enclosures; environmental factors; Flow rates; Flow velocity; growth retardation; Inland waters; lakes; Light intensity; Luminous intensity; Nutrients; Oceanography; Periphyton; Photosynthesis; Phytoplankton; Plankton; Plankton blooms; Spirogyra; Stream flow; temperature; Turbidity; Turbulent flow; Vegetative reproduction; 临界流量; 动态流量; 叶绿素a; 机柜; 条件影响; 浮游植物; 环境变量; 相对抑制率; phytoplankton; environmental variables; enclosure experiment; flow rate
• ISSN: 0254-4059; 2096-5508; 1993-5005; 2523-3521
• DOI: 10.1007/s00343-015-4063-4

To investigate the effects of flow rate on phytoplankton dynamics and related environment variables, a set of enclosure experiments with different flow rates were conducted in an artificial lake. We monitored nutrients, temperature, dissolved oxygen, pH, conductivity, turbidity, chlorophyll-a and phytoplankton levels. The lower biomass in all flowing enclosures showed that flow rate significantly inhibited the growth of phytoplankton. A critical flow rate occurred near 0.06 m/s, which was the lowest relative inhibitory rate. Changes in flow conditions affected algal competition for light, resulting in a dramatic shift in phytoplankton composition, from blue-green algae in still waters to green algae in flowing conditions. These findings indicate that critical flow rate can be useful in developing methods to reduce algal bloom occurrence. However, flow rate significantly enhanced the inter-relationships among environmental variables, in particular by inducing higher water turbidity and vegetative reproduction of periphyton （Spirogyra）. These changes were accompanied by a decrease in underwater light intensity, which consequently inhibited the photosynthetic intensity of phytoplankton. These results warn that a universal critical flow rate might not exist, because the effect of flow rate on phytoplankton is interlinked with many other environmental variables.