Understanding how multiple resources (such light and nutrients) interact with temperature and affect organismal performance is challenging, especially in variable environments. Depending on organismal thermal traits, different performances are expected under fluctuating and constant temperature regimes. These differences between constant and fluctuation conditions might be determined by the availability of resources, as resource availability can influence thermal traits of organisms. In this study, we investigated how the temperature sensitivity of phytoplankton is influenced by multiple resource combinations of light and nutrients, under constant as well as fluctuating temperatures. We exposed the species Scenedesmus armatus to gradients of light intensity and nutrient concentrations (nitrogen and phosphorus) and investigated the effect of three temperature fluctuation scenarios (same frequency and amplitude, but fluctuations around different means). We compared the obtained results with outcomes measured under constant temperature conditions at the different combinations of nutrient and light supply. In both constant and fluctuating temperature scenarios, we found interactive effects of temperature, light and nutrients on growth rates. Differences in performance between constant and fluctuating temperatures with the same mean were influenced by the effect of light and nutrients. This study highlights the importance of considering multiple factors for ecological outcome predictions and showed that effects of fluctuations depend on organismal thermal niche.          

Primary Presenter: Anna Lena Heinrichs, University Oldenburg, ICBM Wilhelmshaven (anna-lena-heinrichs@t-online.de)

Authors:

Johanna Exner, Carl-von-Ossietzky University Oldenburg  ()

Miriam Gerhard, Universidad de la República, Uruguay  ()

Apostolos-Manuel Koussoroplis, Université Clermont Auvergne  ()

Maren Striebel, Carl-von-Ossietzky University Oldenburg, ICBM Wilhelmshaven  (maren.striebel@uol.de)