Distribution of the Harmful Bloom-Forming Cyanobacterium, <i>Microcystis aeruginosa</i>, in 88 Freshwater Environments across Japan

Abstract

Microcystis aeruginosa was quantitatively surveyed in 88 freshwater environments across Japan within 3 weeks in 2011. In order to clarify the distribution pattern of M. aeruginosa at the intra-species level, three major genotypes, which were defined by 16S-23S rRNA inter-transcribed-spacer (ITS) regions, were selectively detected using quantitative real-time PCR assays. Of the 68 sites at which the Microcystis intergenic-spacer region of the phycocyanin (IGS-PC) gene was detected, the M. aeruginosa morphotype-related genotype (MG1) dominated in 41 sites, followed by the non-toxic M. wesenbergii-related genotype (MG3). A correlation analysis showed that total nitrogen and phosphate positively correlated with the abundance of IGS-PC, which positively correlated with microcystin synthetase gene abundance. A redundancy analysis of genotype compositions showed that pH positively correlated with the dominance of MG3 and negatively correlated with MG1, i.e., both toxic and non-toxic genotypes. Our survey of Microcystis populations over a wide area revealed that MG1 is a dominant genotype in Japan.

Nitrous oxide (N2O) synthesis by Microcystis aeruginosa

“…The N2O synthesis rates reported during our study are in the same order of magnitude as the rate previously reported for members of the green microalgae, cyanobacteria, and diatoms (Bauer et al, 2016;Plouviez et al, 2019). Our findings therefore support past predictions of the global relevance of photosynthetic N2O emissions from eutrophic aquatic bodies as Microcystis is globally found and often the dominant genus in these ecosystems (Qian et al, 2010;Kataoka et al, 2020;Zhou et al, 2020). Further research is now needed to quantify N2O emissions from eutrophic aquatic ecosystems where M. aeruginosa abounds.…”

“…Further research is now needed to quantify N2O emissions from eutrophic aquatic ecosystems where M. aeruginosa abounds. This is especially timely considering that the frequency and geographic distribution of harmful algae blooms have increased due to anthropogenic activities (Paerl et al, 2018;Kataoka et al, 2020).…”

“…Microcystis species are cyanobacteria commonly found in eutrophic ecosystems (Xiao et al, 2018;Zhou et al, 2020;Hernandez-Zamora et al, 2021) but the ability of this genus to synthesize N2O is currently unknown. We, therefore, investigated the ability of N2O production by the most notorious bloom-forming cyanobacterium reported in freshwaters and model cyanobacterium M. aeruginosa (Qian et al, 2010;Kataoka et al, 2020;Zhou et al, 2020) under conditions known to induce or impact N2O production in microalgae (Guieysse et al, 2013;Alcantara et al, 2015;Bauer et al, 2016;Plouviez et al, 2017b;Burlacot et al, 2020).…”