Nutritional demands with increasing temperatures: more nutrients or more carbon in a warming world?

CECILIA LASPOUMADERES; CEDRIC MEUNIER; NELLY TREMBLAY; BALSEIRO, ESTEBAN; JAMES ELSER; BEATRIZ MODENUTTI; AMARU MAGNIN; LAURA WOLINSKI; MAARTEN BOERSMA

Brest

Congreso; IMBeR Future Oceans2; 2019

Institute of Marine Research

Temperature and nutrients are key modulators of growth rates in ectotherms. However, little is known on the effect of changing temperatures on nutrient requirements of these organisms. Different hypotheses exist, predicting opposite outcomes: some of them expect higher phosphorus and nitrogen requirements at higher temperatures because of the increased growth rates, whereas others predict higher carbon requirements at higher temperatures due to a higher increase in respiration rate relative to growth and uptake. Here, using the copepod Acartia tonsa, we determine the temperature dependence of all important variables such as feeding, excretion, respiration and assimilation rates for C, N, and P, and the resulting threshold elemental ratio for phosphorus and nitrogen (TERC:N and C:P), and compare these with existing results for the freshwater cladoceran Daphnia magna. If these TER values change with temperature, the ideal diet for an ectotherm would vary with temperature, potentially explaining broad geographic patterns in species? distributions. These findings, may ultimately help predict how expected changes in temperature and nutrient inputs to ecosystems will affect communities.