The combined impact of low temperatures and shifting phosphorus availability on the competitive ability of cyanobacteria

Abstract

In freshwater systems, cyanobacteria are strong competitors under enhanced temperature and eutrophic conditions. Understanding their adaptive and evolutionary potential to multiple environmental states allows us to accurately predict their response to future conditions. To better understand if the combined impacts of temperature and nutrient limitation could suppress the cyanobacterial blooms, a single strain of Microcystis aeruginosa was inoculated into natural phytoplankton communities with different nutrient conditions: oligotrophic, eutrophic and eutrophic with the addition of bentophos. We found that the use of the bentophos treatment causes significant differences in prokaryotic and eukaryotic communities. This resulted in reduced biodiversity among the eukaryotes and a decline in cyanobacterial abundance suggesting phosphorus limitation had a strong impact on the community structure. The low temperature during the experiment lead to the disappearance of M. aeruginosa in all treatments and gave other phytoplankton groups a competitive advantage leading to the dominance of the eukaryotic families that have diverse morphologies and nutritional modes. These results show cyanobacteria have a reduced competitive advantage under certain temperature and nutrient limiting conditions and therefore, controlling phosphorus concentrations could be a possible mitigation strategy for managing harmful cyanobacterial blooms in a future warmer climate.

Long‐term exposure to elevated temperature leads to altered gene expression in a common bloom‐forming cyanobacterium

“…The growth rate and TRN results for M11 ambient and high‐temperature conditions were previously published in Briddon et al (2022). At Month 0 (the start of the two‐year evolution experiment), the growth rate of M11 was significantly higher than M10 (determined using a t ‐test; p < 0.001), but not M12 (Fig.…”

“…The full qPCR results for the strain M11 (including both the ambient and high‐temperature conditions) are published in Briddon et al (2022). Ambient‐temperature M10 showed an increase in gene expression (upregulation) of fivefold to sixfold for the genes clp C1 and clp C2 (at Month 24 compared to Month 0).…”

“…The full methodology for the growth rate measurements and thermal reaction norms (TRNs) for M11 are stated in Briddon et al (2022). The same methodology was used for M10 and M12.…”

“…The full methodology for reverse transcription, quantitative PCR (RT‐qPCR) including primer design, RNA extraction, and cDNA synthesis are stated in Briddon et al (2022). After each growth rate experiment, completed at Months 0, 8, 16 and 24, biomass was collected for the strains M10, M11, and M12 for the ambient and high‐temperature conditions.…”

Influence of salinity, nitrogen and phosphorus concentrations on the physiological and biochemical characteristics of two Chlorophyceae isolated from Fez freshwater, Morocco

“…Conversely, levels of these reserve molecules increase under stressful conditions 5 , 6 . Furthermore, the selection of optimal environmental conditions is of great importance in large-scale cultivation since they influence the competitive capacity of the algae 7 , 8 . As a result, many studies have focused on the cultivation of microalgae under nutrient stress, in particular the limitation or deprivation of nitrogen and phosphorus.…”