Evaluation of the use of eucalyptus to control algae bloom and improve water quality Wei Zhao a , Zheng Zheng a, ⁎, JunLei Zhang a , Saint-Fort Roger b , XingZhang Luo a a Department of Environmental Science and Engineering, Fudan University, Shanghai 200433, PR China b Department of Environmental Science, Mount Royal University, Calgary, AB T3E 6K6, Canada HIGHLIGHTS • Using eucalyptus to control algae blooms was tested for the first time. • Planting eucalyptus was more effective at controlling algae proliferation than eucalyptus leaves extracts. • Allelopathy and nutrients absorption are the primary mechanisms at control- ling algae. • Effect of eucalyptus on diversity and abundance of microbial community structures was negligible. GRAPHICAL ABSTRACT Eucalyptus has the ability to treat eutrophic water body through the interplay of nutrients absorption and alle- lopathy. abstract article info Article history: Received 12 January 2019 Received in revised form 17 February 2019 Accepted 17 February 2019 Available online 19 February 2019 Editor: Frederic Coulon Lakes represent an important source of drinking water resource for human beings. The presence of harmful algae blooms can pose a serious threat to lakes water quality. This study explored the feasibility of using eucalyptus plants and leaves extracts for controlling algae proliferation in an aquatic milieu. After 30 days of treatment, the inhibitory efficiencies were 85.8% and 20.9% for treatments planting eucalyptus and eucalyptus leaves ex- tracts, respectively. The synergistic effects of allelopathy and competitive absorption for macro nutrients were at- tributed to the effective control of algae proliferation in the mesocosm systems. Moreover, the analysis of microbial community structures indicated that eucalyptus plants or leaves extracts had no adverse effect on spe- cies diversity and their relative abundance. The choice of using eucalyptus to control algae bloom will be dictated by environmental and economic considerations within a geographical region. © 2019 Elsevier B.V. All rights reserved. Keywords: Eucalyptus Allelopathy Macro nutrient competition Algae blooms 1. Introduction Harmful algae blooms (HABs) have become a worldwide phenome- non. Its impact can lead to the increase of water turbidity, decrease of species diversity of phytoplankton, production of hepatotoxin microcystin etc. which can lead to a serious threat to humans and ani- mals health (Dong et al., 2016; H.J. Wang et al., 2016). Several mitigative measures, primarily driven by economic factors, have been applied with relatively moderate success to control algae populations. Such control measures include algaecides (Crafton et al., 2018), electron beam irradi- ation (S.Y. Liu et al., 2014), and photocatalysis (Liu et al., 2015). Science of the Total Environment 667 (2019) 412–418 ⁎ Corresponding author. E-mail address: zzhenghj@fudan.edu.cn (Z. Zheng). https://doi.org/10.1016/j.scitotenv.2019.02.276 0048-9697/© 2019 Elsevier B.V. All rights reserved. Contents lists available at ScienceDirect Science of the Total Environment journal homepage: www.elsevier.com/locate/scitotenv