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Co-occurring microorganisms regulate the succession of cyanobacterial harmful algal blooms
Citation:
Wang, K., X. Mou, H. Cao, I. Struewing, Hubert Allen, AND J. Lu. Co-occurring microorganisms regulate the succession of cyanobacterial harmful algal blooms. ENVIRONMENTAL POLLUTION. Elsevier Science Ltd, New York, NY, 288:117682, (2021). https://doi.org/10.1016/j.envpol.2021.117682
Impact/Purpose:
The efforts towards reduction of nutrient contamination of surface waters has greatly gained attention to mitigate increasing incidences of harmful cyanobacterial blooms (HABs). Little attention has been paid on the roles and importance of nutrient metabolic pathways within the cyanobacterial communities during HABs. The community successions and their metabolic pathway were revealed and found to be associated with low levels of nitrogen and high level of phosphorus, and with shift of cyanbacterial dominance from nitrogen fixing to bloom-forming populations and production of cyanotoxin. This information can be used to aid in the understanding the impact that TN and TP have on cyanobacterial community successions and cyanotoxin production and aid in making management decisions related to harmful algal blooms. OW, regional offices, scientists and water quality managers could be interested in the results.
Description:
Cyanobacterial harmful algal blooms (CyanoHABs) have been found to transmit from N2 fixer-dominated to non-N2 fixer-dominated in many freshwater environments when the supply of N decreases. To elucidate the mechanisms underlying such “counter-intuitive” CyanoHAB species succession, metatranscriptomes (biotic data) and water quality-related variables (abiotic data) were analyzed weekly during a bloom season in Harsha Lake, a multipurpose lake that serves as a drinking water source and recreational ground. Our results showed that CyanoHABs in Harsha Lake started with N2-fixing Anabaena in June (ANA stage) when N was high, and transitioned to non-N2-fixing Microcystis- and Planktothrix-dominated in July (MIC-PLA stage) when N became limited (low TN/TP). Meanwhile, the concentrations of cyanotoxins, i.e., microcystins were significantly higher in the MIC-PLA stage. Water quality results revealed that N species (i.e., TN, TN/TP) and water temperature were significantly correlated with cyanobacterial biomass. Expression levels of several C- and N-processing-related cyanobacterial genes were highly predictive of the biomass of their species. More importantly, the biomasses of Microcystis and Planktothrix were also significantly associated with expressions of microbial genes (mostly from heterotrophic bacteria) related to processing organic substrates (alkaline phosphatase, peptidase, carbohydrate-active enzymes) and cyanophage genes. Collectively, our results suggest that besides environmental conditions and inherent traits of specific cyanobacterial species, the development and succession of CyanoHABs are regulated by co-occurring microorganisms. Specifically, the co-occurring microorganisms can alleviate the nutrient limitation of cyanobacteria by remineralizing organic compounds.
URLs/Downloads:
DOI: Co-occurring microorganisms regulate the succession of cyanobacterial harmful algal blooms
https://pubmed.ncbi.nlm.nih.gov/34271516/