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Letter
Mixotrophic organisms become more heterotrophic with rising temperature
Article first published online: 23 NOV 2012
DOI: 10.1111/ele.12033
© 2012 Blackwell Publishing Ltd/CNRS
Additional Information
How to Cite
Ecology Letters (2013) 16: 225–233
Publication History
- Issue published online: 15 JAN 2013
- Article first published online: 23 NOV 2012
- Manuscript Accepted: 14 OCT 2012
- Manuscript Revised: 12 SEP 2012
- Manuscript Received: 6 AUG 2012
Funded by
- the Netherlands Institute of Ecology
- the Water Programme of the Earth and Life Sciences Foundation
Keywords:
- Autotrophy;
- global warming;
- heterotrophy;
- metabolic theory;
- mixotrophy;
- microbial loop;
- photosynthesis;
- plankton communities
Abstract
The metabolic theory of ecology predicts that temperature affects heterotrophic processes more strongly than autotrophic processes. We hypothesized that this differential temperature response may shift mixotrophic organisms towards more heterotrophic nutrition with rising temperature. The hypothesis was tested in experiments with the mixotrophic chrysophyte Ochromonas sp., grown under autotrophic, mixotrophic and heterotrophic conditions. Our results show that (1) grazing rates on bacterial prey increased more strongly with temperature than photosynthetic electron transport rates, (2) heterotrophic growth rates increased exponentially with temperature over the entire range from 13 to 33 °C, while autotrophic growth rates reached a maximum at intermediate temperatures and (3) chlorophyll contents during mixotrophic growth decreased at high temperature. Hence, the contribution of photosynthesis to mixotrophic growth strongly decreased with temperature. These findings support the hypothesis that mixotrophs become more heterotrophic with rising temperature, which alters their functional role in food webs and the carbon cycle.