Metabolic traits predict the effects of warming on phytoplankton competition

Abstract

Understanding how changes in temperature affect interspecific competition is critical for predicting changes in ecological communities with global warming. Here, we develop a theoretical model that links interspecific differences in the temperature dependence of resource acquisition and growth to the outcome of pairwise competition in phytoplankton. We parameterised our model with these metabolic traits derived from six species of freshwater phytoplankton and tested its ability to predict the outcome of competition in all pairwise combinations of the species in a factorial experiment, manipulating temperature and nutrient availability. The model correctly predicted the outcome of competition in 72% of the pairwise experiments, with competitive advantage determined by difference in thermal sensitivity of growth rates of the two species. These results demonstrate that metabolic traits play a key role in determining how changes in temperature influence interspecific competition and lay the foundation for mechanistically predicting the effects of warming in complex, multi-species communities.

Temperature‐dependence of minimum resource requirements alters competitive hierarchies in phytoplankton

“…This may explain temperature-induced increases in the nitrogen content of phytoplankton biomass, relative to phosphorus content (Yvon-Durocher et al 2017). Similarly, the temperaturedependence of four metabolic traits enabled the correct prediction of 72% of competition experiments between pairs of phytoplankton species (Bestion et al 2018). Such mechanistic insights may therefore allow the identification of generalities governing the temperature dependencies and sensitivities of species' resource requirement.…”

“…For example, reaction rates of phosphorus-rich ribosomes are more temperature-sensitive than nitrogen-rich photosynthetic proteins, suggesting that climate warming may shift elemental stoichiometry and resource requirements (Martiny et al 2013, Yvon-Durocher et al 2015, Yuan and Chen 2015. Although previous study has experimentally tested the effect of temperature on competition between the pairs of species (Bestion et al 2018), how temperature influences species minimum resource requirements and competitive hierarchies in multispecies assemblages remains poorly understood.…”

Effect of phytoplankton size diversity on primary productivity in the North Pacific: trait distributions under environmental variability

“…Thus, similar to nutrient uptake traits, the lack of a strong complementarity effect of size diversity on productivity is therefore not surprising. For future studies it would certainly be worthwhile to include more traits, such as optimal growth temperature and light that are not strongly dependent on size, particularly in areas with substantial seasonal or spatial fluctuations of temperature or light (Goebel et al 2014;Vallina et al 2017;Bestion et al 2018).…”

Abrupt declines in marine phytoplankton production driven by warming and biodiversity loss in a microcosm experiment

“…Thermal tolerance curves for phytoplankton exhibit characteristic unimodality and left-skew, where fitness declines more sharply above the optimum than below (Schaum et al 2017;Padfield et al 2017). Given the large interspecific variability in thermal tolerance among phytoplankton (Thomas et al 2012(Thomas et al , 2016Boyd et al 2013;Barton & Yvon-Durocher 2019) and the importance of thermal tolerance for species interactions (Bestion et al 2018a), we hypothesised that when warming drives temperatures above the thermal optimum for some species but not others, the slope of the relationship between biodiversity and ecosystem functioning should become steeper because more diverse communities will have a higher probability of including species that are able to tolerate warming and maintain ecosystem function as temperature rises.…”