TITLE:
Effect of Small-Scale Turbulence on the Growth and Metabolism of Microcystis aeruginosa
AUTHORS:
Anne Wilkinson, Miki Hondzo, Michele Guala
KEYWORDS:
Harmful Algal Blooms, Microcystis aeruginosa, Cyanobacteria, Turbulence, Metabolic Response, Microcystin
JOURNAL NAME:
Advances in Microbiology,
Vol.6 No.5,
April
27,
2016
ABSTRACT: Microcystis aeruginosa is a single-celled cyanobacterium, forming large colonies on the surface of
freshwater ecosystems during summer, and producing a toxin (microcystin) that in high concentration
can be harmful to humans and animals. These toxic effects can be governed by abiotic environmental
conditions including water temperature, light, nutrient abundance, and fluid motion.
We investigated the effect of small-scale turbulence on the growth and metabolism of Microcystis
aeruginosa using field measurements and laboratory bioreactor investigations. The laboratory
setup included two underwater speakers, generating a quasi-homogeneous turbulent flow with
turbulent kinetic energy dissipation rates up to 10-6 m2/s3, comparable to field values in the lacustrine
photic zone. The role of turbulence is quantified by comparing cell number, dissolved oxygen
production/uptake, and inorganic carbon uptake in stagnant condition and two sets of experiments
with turbulent conditions, quantified by the Taylor micro-scale Reynolds number at Reλ =
15 and Reλ = 33. The results suggest that turbulence mediates the metabolism of Microcystis aeruginosa measured by the net oxygen production, oxygen uptake, and inorganic carbon uptake. Furthermore,
small-scale turbulence marginally influenced Microcystis growth rate estimated from
cell population concentration (-5% and 11% for Reλ = 33 and Reλ = 15, respectively, as compared
to stagnant conditions).