Multi-strain analysis reveals distinct light and temperature growth optima for morphology similar cyanobacteria

Abstract

Picocyanobacteria are small cyanoprokaryotes (0.2-3 μm) that play a large role in global primary production. Given the effects of climate change, picocyanobacterial distribution and localized growth rates may produce overgrowth that can cause negative effects on global biogeochemical cycles and food webs. In this study, we developed a matrix of three light conditions and four ecologically relevant temperature conditions to test the growth rates of six diverse strains of picocyanobacteria in order to predict how picocyanobacteria will grow as global water temperatures increase. Using modified Gompertz models and generalized additive modelling approaches, I uncovered a diverse range of growth optima for both cell count growth rates and chlorophyll growth rates that reveal a general preference for warmer temperatures. Given localized climate trends, we can predict that picocyanobacterial growth rates will increase as much as 40% within the coming century.