Biological effects of harvesting harmful algal blooms on submerged macrophytes and leaf biofilms: A mesocosm experiment

Abstract

Harvesting harmful algal blooms is useful for treating eutrophicated water, but the effect of harvest intensity on aquatic organisms has not been reported. This study investigated the biological effects of algal harvest on submerged macrophytes and leaf biofilms. Harvesting changed the content of total dissolved phosphorus, ammonia nitrogen and dissolved oxygen in water, and suitable harvest intensity (70%) can reduce the content of microcystin-LR. Meanwhile, lower levels of malondialdehyde, glutathione, superoxide dismutase, and catalase in plants, as well as the growth of submerged macrophytes, also indicated that the optimal harvest intensity was 70%. Different harvest intensities changed the content of polysaccharide and protein in biofilms, as well as the abundances and structure of the microbial community. Moreover, the reduction in N-acylated-L-homoserine lactone content in biofilms indicated that different intensities of algal harvest induced structure alternations of biofilm and affected the ecological functions. This work contributes to understanding the ecological impact of algal harvest and provides a more appropriate harvest intensity for practical applications.