Occurrence of Raphidiopsis raciborskii blooms in cool waters: Synergistic effects of nitrogen availability and ecotypes with adaptation to low temperature

Nannan Jia; Yilang Wang; Yuying Guan; Youxin Chen; Renhui Li; Gongliang Yu

doi:10.1016/j.envpol.2020.116070

Occurrence of Raphidiopsis raciborskii blooms in cool waters: Synergistic effects of nitrogen availability and ecotypes with adaptation to low temperature

Environ Pollut. 2021 Feb 1:270:116070. doi: 10.1016/j.envpol.2020.116070. Epub 2020 Nov 11.

Authors

Nannan Jia¹, Yilang Wang¹, Yuying Guan², Youxin Chen³, Renhui Li⁴, Gongliang Yu⁵

Affiliations

¹ Key Laboratory of Algal Biology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, 430072, China; University of Chinese Academy of Sciences, Beijing, 100039, China.
² School of Environment, Nanjing Normal University, Nanjing, 210046, China.
³ Key Laboratory of Algal Biology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, 430072, China.
⁴ Key Laboratory of Algal Biology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, 430072, China; College of Life and Environmental Sciences, Wenzhou University, Wenzhou, 325039, China.
⁵ Key Laboratory of Algal Biology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, 430072, China. Electronic address: yugl@ihb.ac.cn.

PMID: 33223338
DOI: 10.1016/j.envpol.2020.116070

Abstract

Raphidiopsis raciborskii is a diazotrophic and potentially toxic cyanobacterium. To date, this species has successfully invaded many regions from the tropics to sub-tropical and temperate regions, typically forming blooms at temperatures greater than 25 °C. However, there have been a few cases in which R. raciborskii blooms have occurred at low temperatures (below 15 °C), but its cause and mechanisms remain unclear. In this study, field investigations revealed that R. raciborskii blooms occurred at 10-15 °C in Lake Xihu, Yunnan, China. The biomass of R. raciborskii was found to be positively related to nitrate concentrations in this lake. Three strains of R. raciborskii, two isolated from Lake Xihu (CHAB 6611 and CHAB 6612) and one from Lushui Reservoir in central China (CHAB 3409), were used for growth experiments at 15 °C. The three strains exhibited genotypic (16S rRNA and ITS-L genes) and physiological differences in response to nitrogen concentrations at low temperature. The growth rates of strains CHAB 6611 and CHAB 6612 increased with nitrogen concentration while CHAB 3409 could not grow at 15 °C. Furthermore, the growth and phenotypic responses of CHAB 6611 and CHAB 6612 to nitrogen concentrations were different, despite the closer genetic relationship shared by these two strains. Thus, increased nitrogen concentration in water may enhance the biological availability and utilization of nitrogen by R. raciborskii, which is the external promoter, leading to improving the resistance of R. raciborskii to low temperature. The internal cause is the presence of ecotypes in R. raciborskii populations with adaptation to low temperature. With increasing global eutrophication, the distribution range of R. raciborskii as well as the scale of its blooms will increase. As such, the risk of exposure of aquatic biota and humans to cylindrospermopsin is also expected to increase.

Keywords: Cyanobacterial blooms; Ecotypes; Low temperature; Nitrogen availability; Raphidiopsis raciborskii.

MeSH terms

China
Cylindrospermopsis
Ecotype*
Humans
Nitrogen*
RNA, Ribosomal, 16S
Temperature

Substances

RNA, Ribosomal, 16S
Nitrogen

Supplementary concepts

Cylindrospermopsis raciborskii