title: Allelopathic effect boosts Chrysosporum ovalisporum dominance in summer at the expense of Microcystis panniformis in a shallow coastal water body.
abstract: The increased occurrence of harmful cyanobacterial species and, with this, higher frequency of cyanobacteria blooms, closely associated with eutrophication and climate change, have attracted increasing attention worldwide. However, competition mechanisms between the different bloom-forming cyanobacteria species remain to be elucidated. In this paper, for the first time, the allelopathic effect of the cyanobacterium Chrysosporum ovalisporum on the cyanobacterium Microcystis panniformis is reported. The results of our study conducted in a Chinese shallow coastal water body demonstrated that the biomass of M. panniformis was relatively low during the C. ovalisporum blooming period. Co-cultivation of a C. ovalisporum strain with a M. panniformis strain showed strong inhibition of the growth of M. panniformis but stimulation of C. ovalisporum. Thus, filtrate of C. ovalisporum culture had a strong inhibitory effect on the performance of M. panniformis by decreasing the maximum optical quantum yield (Fv/Fm), the electron transport rate (ETR) of PS II and the onset of light saturation (Ik) and by increasing the alkaline phosphatase (ALP) activity and superoxide dismutase (SOD) activity of M. panniformis. Our results suggest that the inter-specific allelopathic effect plays an important role in the competition between different cyanobacteria species. We foresee the importance of C. ovalisporum to intensify in a future warmer world, not least in small- to medium-sized, warm and high conductivity coastal water bodies.
authors.affiliation: College of Fisheries and Life Science, Shanghai Ocean University, Shanghai, China.
authors.forename: Wei
authors.initials: W
authors.lastname: Zhang
authors.affiliation: Department of Bioscience, Aarhus University, Silkeborg, Denmark.|Sino-Danish Centre for Education and Research (SDC), Beijing, China.
authors.forename: Erik
authors.initials: E
authors.lastname: Jeppesen
authors.affiliation: College of Fisheries and Life Science, Shanghai Ocean University, Shanghai, China.
authors.forename: Mengmeng
authors.initials: M
authors.lastname: Wang
authors.affiliation: College of Fisheries and Life Science, Shanghai Ocean University, Shanghai, China.
authors.forename: Xiaoying
authors.initials: X
authors.lastname: Xu
authors.affiliation: College of Fisheries and Life Science, Shanghai Ocean University, Shanghai, China. lqwang@shou.edu.cn.
authors.forename: Liqing
authors.initials: L
authors.lastname: Wang
mesh_terms: D064089:Allelopathy; D046890:Aphanizomenon / Q000502:physiology*; D018533:Biomass; D046931:Microcystis / Q000502:physiology*; D009792:Oceans and Seas; D012621:Seasons; D014867:Water
chemical_list: D014867:Water
keywords: Allelopathy; Bloom; Chrysosporum ovalisporum; Competition; Cylindrospermopsin; Microcystis panniformis