title: Heated relations: temperature-mediated shifts in consumption across trophic levels.
abstract: A rise in temperature will intensify the feeding links involving ectotherms in food webs. However, it is unclear how the effects will quantitatively differ between the plant-herbivore and herbivore-carnivore interface. To test how warming could differentially affect rates of herbivory and carnivory, we studied trophic interaction strength in a food chain comprised of green algae, herbivorous rotifers and carnivorous rotifers at 10, 15, 20 and 25°C. We found significant warming-induced changes in feeding by both herbivorous and carnivorous rotifers, but these responses occurred at different parts of the entire temperature gradient. The strongest response of the per capita herbivore's ingestion rate occurred due to an increase in temperature from 15 to 20°C (1.9 fold: from 834 to 1611 algal cells per h(-1)) and of the per capita carnivore's ingestion rate from 20 to 25°C (1.6 fold: from 1.5 to 2.5 prey h(-1)). Handling time, an important component of a consumer's functional response, significantly decreased from 15 to 20°C in herbivorous rotifers. In contrast, it decreased from 20 to 25°C in carnivorous rotifers. Attack rates significantly and strongly increased from 10 to 25°C in the herbivorous animals, but not at all in the carnivores. Our results exemplify how the relative forces of top-down control exerted by herbivores and carnivores may strongly shift under global warming. But warming, and its magnitude, are not the only issue: If our results would prove to be representative, shifts in ectotherm interactions will quantitatively differ when a 5°C increase starts out from a low, intermediate or high initial temperature. This would imply that warming could have different effects on the relative forces of carnivory and herbivory in habitats differing in average temperature, as would exist at different altitudes and latitudes.
authors.affiliation: Department of Ecology and Ecosystem modelling, Potsdam University, Potsdam, Germany.
authors.forename: Linda I
authors.initials: LI
authors.lastname: Seifert
authors.affiliation: Department of Ecology and Ecosystem modelling, Potsdam University, Potsdam, Germany; School of Biological Science, Queen's University of Belfast, Belfast, United Kingdom.
authors.forename: Francisco
authors.initials: F
authors.lastname: de Castro
authors.affiliation: Department of Ecology and Ecosystem modelling, Potsdam University, Potsdam, Germany.
authors.forename: Arnim
authors.initials: A
authors.lastname: Marquart
authors.affiliation: Department of Ecology and Ecosystem modelling, Potsdam University, Potsdam, Germany; Berlin-Brandenburg Institute of Advanced Biodiversity Research (BBIB), Berlin, Germany.
authors.forename: Ursula
authors.initials: U
authors.lastname: Gaedke
authors.affiliation: Department of Ecology and Ecosystem modelling, Potsdam University, Potsdam, Germany.
authors.forename: Guntram
authors.initials: G
authors.lastname: Weithoff
authors.affiliation: Department of Ecology and Ecosystem modelling, Potsdam University, Potsdam, Germany; Institute of Environmental Sciences (CML), Leiden University, Leiden, the Netherlands.
authors.forename: Matthijs
authors.initials: M
authors.lastname: Vos
mesh_terms: D000818:Animals; D000460:Chlorophyta / Q000502:physiology*; D020387:Food Chain; D006358:Hot Temperature; D008954:Models, Biological; D012403:Rotifera / Q000502:physiology*