Are laboratory growth rate experiments relevant to explaining bloom-forming cyanobacteria distributions at global scale?

Man Xiao; David P Hamilton; Katherine R O'Brien; Matthew P Adams; Anusuya Willis; Michele A Burford

doi:10.1016/j.hal.2019.101732

Are laboratory growth rate experiments relevant to explaining bloom-forming cyanobacteria distributions at global scale?

Harmful Algae. 2020 Feb:92:101732. doi: 10.1016/j.hal.2019.101732. Epub 2019 Dec 24.

Authors

Man Xiao¹, David P Hamilton², Katherine R O'Brien³, Matthew P Adams⁴, Anusuya Willis⁵, Michele A Burford⁶

Affiliations

¹ Australian Rivers Institute, Griffith University, Nathan, Australia; School of Environment and Science, Griffith University, Nathan, Australia. Electronic address: man.xiao@griffithuni.edu.au.
² Australian Rivers Institute, Griffith University, Nathan, Australia.
³ School of Chemical Engineering, University of Queensland, St Lucia, Australia.
⁴ School of Chemical Engineering, University of Queensland, St Lucia, Australia; School of Earth and Environmental Sciences, University of Queensland, St Lucia, Australia; School of Biological Sciences, University of Queensland, St Lucia, Australia.
⁵ Australian Rivers Institute, Griffith University, Nathan, Australia; Australian National Algae Culture Collection, CSIRO, Hobart, Tasmania, Australia.
⁶ Australian Rivers Institute, Griffith University, Nathan, Australia; School of Environment and Science, Griffith University, Nathan, Australia.

PMID: 32113600
DOI: 10.1016/j.hal.2019.101732

Abstract

Predicting algal population dynamics using models informed by experimental data has been used as a strategy to inform the management and control of harmful cyanobacterial blooms. We selected toxic bloom-forming species Microcystis spp. and Raphidiopsis raciborskii (basionym Cylindrospermopsis raciborskii) for further examination as they dominate in 78 % and 17 %, respectively, of freshwater cyanobacterial blooms (cyanoHABs) reported globally over the past 30 years. Field measurements of cyanoHABs are typically based on biomass accumulation, but laboratory experiments typically measure growth rates, which are an important variable in cyanoHAB models. Our objective was to determine the usefulness of laboratory studies of these cyanoHAB growth rates for simulating the species dominance at a global scale. We synthesized growth responses of M. aeruginosa and R. raciborskii from 20 and 16 culture studies, respectively, to predict growth rates as a function of two environmental variables, light and temperature. Predicted growth rates of R. raciborskii exceeded those of M. aeruginosa at temperatures ≳ 25 °C and light intensities ≳ 150 μmol photons m^-2 s^-1. Field observations of biomass accumulation, however, show that M. aeruginosa dominates over R. raciborskii, irrespective of climatic zones. The mismatch between biomass accumulation measured in the field, and what is predicted from growth rate measured in the laboratory, hinders effective use of culture studies to predict formation of cyanoHABs in the natural environment. The usefulness of growth rates measured may therefore be limited, and field experiments should instead be designed to examine key physiological attributes such as colony formation, buoyancy regulation and photoadaptation. Improving prediction of cyanoHABs in a changing climate requires a more effective integration of field and laboratory approaches, and an explicit consideration of strain-level variability.

Keywords: Colony formation; Cylindrospermopsis raciborskii (Raphidiopsis raciborskii); Light; Microcystis spp.; Numerical modelling; Temperature.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Cyanobacteria*
Cylindrospermopsis*
Fresh Water
Microcystis*

Supplementary concepts

Cylindrospermopsis raciborskii