Plasticity in algal stoichiometry: Experimental evidence of a temperature‐induced shift in optimal supply N:P ratio

Abstract

There is growing empirical and theoretical evidence for a positive relationship between the nitrogen (N)-to-phosphorus (P) ratio of phytoplankton and temperature. However, few have tested how the optimal supply N:P ratio; the dissolved N:P ratio at which nutrient limitation switches from one element to the other, responds to temperature. In this study, we conducted a factorial experiment crossing 12 temperature levels with 8 supply N:P ratios to determine the effect of temperature acclimation on the optimal supply N:P ratio of the microalgae Chlamydomonas reinhardtii. We found that the optimal supply N:P increased in a sigmoidal manner from 26.5 to 36.5 (atomic ratio) over a temperature gradient spanning from 10 to 188C, with the steepest change around 158C. This result is in accordance with trends observed for cellular and seston N:P ratios, and indicates that phytoplankton populations may be shifted toward N-limitation in a scenario of warmer waters.

Phytoplankton community responses to temperature fluctuations under different nutrient concentrations and stoichiometry

“…, Thrane et al. , Verbeek et al. ) or the effect of temperature variability independently (Vasseur et al.…”

“…Nutrient supply has empirically been shown to interact strongly with temperature (Thrane et al. , Marañón et al. , Verbeek et al.…”

“…Moreover, recent studies have analyzed the effect of temperature on the phytoplankton resource use and stoichiometry, showing that higher temperatures may cause an increase in the phytoplankton optimal N:P supply ratio (Thrane et al. ) as in the phytoplankton intracellular N:P ratios (Yvon‐Durocher et al. ).…”

Impacts of Nitrogen and Phosphorus: From Genomes to Natural Ecosystems and Agriculture

“…For example, older tropical soils are richer in N than P, whereas soils of recently glaciated regions at higher latitudes show the opposite pattern, implying reduced N:P ratios in colder areas (Reich and Oleksyn, 2004). Latitudinal and temperature-related changes in N:P likely reflect a higher demand for ribosomes (and thus P) to maintain sufficient protein synthesis at lower temperatures (Toseland et al, 2013;Thrane et al, 2017). This apparent link between temperature and stoichiometry in primary producers is perhaps unsurprising given that temperature drives the rates of many biological processes, including photosynthesis (C gain) and N and P uptake from the environment.…”

“…At the genomic level, transcription rates in plants also increase with temperature (Sidaway-Lee et al, 2014). The higher demands for ribosomes at lower temperatures may occur to maintain protein synthesis or arise from the increased number of stored immature ribosomes in the nucleolus (Leitch et al, 1995), which can also translate into higher P-demands (and lower N:P) (Woods et al, 2003;Toseland et al, 2013;Thrane et al, 2017).…”