High predictability of direct competition between marine diatoms under different temperatures and nutrient states. Issue 14 (3rd June 2020)

• Record Type: Journal Article
• Authors: Siegel, Philipp; Baker, Kirralee G.; Low‐Décarie, Etienne; Geider, Richard J.
• Is Part Of: Ecology and evolution. Volume 10:Issue 14(2020)
• Page Start: 7276
• Page End: 7290
• Publication Date: 2020-06-03
• Subjects: competition -- diatoms -- phytoplankton -- thermal performance; Ecology -- Periodicals; Evolution -- Periodicals; 577.05
• DOI: 10.1002/ece3.6453
• Languages: English
• ISSNs: 2045-7758

Abstract

Abstract: The distribution of marine phytoplankton will shift alongside changes in marine environments, leading to altered species frequencies and community composition. An understanding of the response of mixed populations to abiotic changes is required to adequately predict how environmental change may affect the future composition of phytoplankton communities. This study investigated the growth and competitive ability of two marine diatoms, Phaeodactylum tricornutum and Thalassiosira pseudonana, along a temperature gradient (9–35°C) spanning the thermal niches of both species under both high‐nitrogen nutrient‐replete and low‐nitrogen nutrient‐limited conditions. Across this temperature gradient, the competitive outcome under both nutrient conditions at any assay temperature, and the critical temperature at which competitive advantage shifted from one species to the other, was well predicted by the temperature dependencies of the growth rates of the two species measured in monocultures. The temperature at which the competitive advantage switched from P. tricornutum to T. pseudonana increased from 18.8°C under replete conditions to 25.3°C under nutrient‐limited conditions. Thus, P. tricornutum was a better competitor over a wider temperature range in a low N environment. Being able to determine the competitive outcomes from physiological responses of single species to environmental changes has the potential to significantly improve the predictive power of phytoplankton spatial distribution and community composition models. Abstract : An understanding of the response of mixed populations to abiotic changes is required in order to adequately predict the future composition of phytoplankton communities. This study investigated the growth and competitive ability of two marine diatoms, Phaeodactylum tricornutum and Thalassiosira pseudonana, along a temperature gradient spanning the thermal niches of both species (from 9°C to 35°C) under high‐nitrogen and low‐nitrogen conditions. Competitive outcomes between the two diatoms were highly predictable based on their monoculture growth performances, indicating that their isolated performance can be used to infer competitive ability and resulting community structure.