Mechanisms of attachment and distribution of Nitzschia and Fragilaria at different flow rates

Abstract

Algae in rivers will accumulate on the surface of bridges and other structures in water with the increase of time, which will pollute the water environment and cause serious corrosion on the surface of structures. Extensive literature studies have shown that flow rate as the basic hydrodynamic condition significantly affects the growth and aggregation of algae, yet how different flow rate influences the aggregation and distribution of attached algae is relatively unexplored. In this work, used microscopic observation and high-throughput sequencing combined with a field hanging test to compare the mechanism of attachment and distribution of Nitzschia and Fragilaria at the flow rates of 0.794 m/s and 0.538 m/s, respectively. Mechanistic study shows that the high flow rate reduced the species abundance ca.10 % under the same conditions by increasing the interaction between hydrodynamic and gravity. It found an improvement in species distribution uniformity in different places and periods showed by high flow rate when contrasted with low flow rate. This mechanism offers mechanistic insights into preventing corrosion and fouling of attached algae.