Environmental impacts on single-cell variation within a ubiquitous diatom: The role of growth rate.

Cédric Léo Meunier,Elisabeth Groß,Arga Chandrashekar Anil,Maarten Boersma

doi:10.1371/journal.pone.0251213

Abstract

Morphological and physiological characteristics of phytoplankton cells are highly sensitive to changes in environmental conditions and, in turn, influence the dynamics of phytoplankton populations and communities. To cope with environmental change, trait variability and phenotypic plasticity may play an important role. Since global change comprises simultaneous changes in abiotic parameters, we assessed the impact of multiple drivers on functional traits of the diatom Thalassiosira (Conticribra) weissflogii by manipulating concurrently temperature, pCO2, and dissolved nitrogen:phosphorus (N:P) ratio. We tested three scenarios: ambient (ambient temperature and atmospheric pCO2; 16 N:P ratio), moderate future scenario (+1.5°C and 800 ppm CO2; 25 N:P ratio), and more severe future scenario (+3°C and 1000 ppm CO2; 25 N:P ratio). We applied flow cytometry to measure on single-cell levels to investigate trait variability and phenotypic plasticity within one strain of diatoms. Growth rates differed significantly between the treatments and were strongly correlated with cell size and cellular chlorophyll a content. We observed a negative correlation of growth rate with chlorophyll a variability among single strain populations and a negative correlation with the phenotypic plasticity of cell size, i.e. when growth rates were higher, the cell size cell-to-cell variability within cultures was lower. Additionally, the phenotypic plasticity in cell size was lower under the global change scenarios. Overall, our study shows that multiple traits are interlinked and driven by growth rate and that this interconnection may partly be shaped by environmental factors.

Highlights

Phytoplankton are responsible for about 50% of Earth’s primary production [1], with diatoms accounting for about half of this [2,3]
The higher temperature and pCO2 in the RCP 6.0 and RCP 8.5 scenarios resulted in higher maximum growth rates in the exponential growth phase, and the RCP 6.0 and RCP 8.5 cultures reached the stationary phase one and two days earlier than the ambient cultures, respectively
We observed that realistic future global change scenarios significantly influence the growth rate of the diatom species T. weissflogii

Summary

Introduction

Phytoplankton are responsible for about 50% of Earth’s primary production [1], with diatoms accounting for about half of this [2,3]. Phytoplankton form the basis of most marine food webs. Diatoms and phytoplankton in general can serve as indicators of ecosystem change since they are sensitive to shifts in environmental conditions. This is important in the context of regional and global change, since human activities and associated increases in greenhouse gas emissions have led to simultaneous. Environmental impacts on single-cell variation within a ubiquitous diatom

Methods

Results

Discussion

Conclusion