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Warming and resource availability shift food web structure and metabolism.

O'Connor MI, Piehler MF, Leech DM, Anton A, Bruno JF - PLoS Biol. (2009)

Bottom Line: Consistent with predictions based on universal metabolic responses to temperature, we found that warming strengthened consumer control of primary production when resources were augmented.Warming shifted food web structure and reduced total biomass despite increases in primary productivity in a marine food web.These results demonstrate that small temperature changes could dramatically shift food web dynamics and provide a general, species-independent mechanism for ecological response to environmental temperature change.

View Article: PubMed Central - PubMed

Affiliation: Curriculum in Ecology, The University of North Carolina, Chapel Hill, Chapel Hill, North Carolina, USA. oconnor@nceas.ucsb.edu

ABSTRACT
Climate change disrupts ecological systems in many ways. Many documented responses depend on species' life histories, contributing to the view that climate change effects are important but difficult to characterize generally. However, systematic variation in metabolic effects of temperature across trophic levels suggests that warming may lead to predictable shifts in food web structure and productivity. We experimentally tested the effects of warming on food web structure and productivity under two resource supply scenarios. Consistent with predictions based on universal metabolic responses to temperature, we found that warming strengthened consumer control of primary production when resources were augmented. Warming shifted food web structure and reduced total biomass despite increases in primary productivity in a marine food web. In contrast, at lower resource levels, food web production was constrained at all temperatures. These results demonstrate that small temperature changes could dramatically shift food web dynamics and provide a general, species-independent mechanism for ecological response to environmental temperature change.

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Effects of temperature on metabolism and food web structure.(A) Temperature (1/kT for T in Kelvin) dependence of photosynthesis- (PS, slope = −0.32 eV) and respiration- (R, slope = −0.65 eV) based mass-normalized resting metabolic rate (mmol O2/d pg Cαh) (Adapted from Allen et al., 2005 [10], Lopez-Urrutia et al., 2006 [9]). (B) Four possible effects of warming on food web structure and biomass depend on resource availability and the importance of consumer-controlled (CC) or resource-controlled (RC) food web dynamics. Relative size of boxes and ovals indicate standing biomass stocks for the simplest of food webs comprising herbivores (Herb.) and primary producers (P. P.).
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pbio-1000178-g001: Effects of temperature on metabolism and food web structure.(A) Temperature (1/kT for T in Kelvin) dependence of photosynthesis- (PS, slope = −0.32 eV) and respiration- (R, slope = −0.65 eV) based mass-normalized resting metabolic rate (mmol O2/d pg Cαh) (Adapted from Allen et al., 2005 [10], Lopez-Urrutia et al., 2006 [9]). (B) Four possible effects of warming on food web structure and biomass depend on resource availability and the importance of consumer-controlled (CC) or resource-controlled (RC) food web dynamics. Relative size of boxes and ovals indicate standing biomass stocks for the simplest of food webs comprising herbivores (Herb.) and primary producers (P. P.).

Mentions: The prevailing conceptual framework for understanding effects of ocean temperature on food webs is based on the view that consumer production is predominantly controlled indirectly by temperature effects on primary production [6],[7]. According to this model, increased primary productivity and net autotrophy also increase CO2 uptake of the whole food web [8],[9]. Yet recently developed metabolic theory and a meta-analysis indicate that heterotrophic (respiration-limited) metabolism is more sensitive to changing temperature than autotrophic (photosynthesis-limited) metabolism and production (Figure 1A) [9],[10], suggesting stronger consumer-driven control with warming. Greater consumer control of primary production would lead to increased heterotrophy and less phytoplankton standing stock (Figure 1B-ii). In either model, the response of food web productivity and structure to changing environmental temperature may be determined by general processes and not the specific responses of component species, and thus could represent a critical step forward in efforts to forecast the impacts of climate change on ecological communities [11],[12].


Warming and resource availability shift food web structure and metabolism.

O'Connor MI, Piehler MF, Leech DM, Anton A, Bruno JF - PLoS Biol. (2009)

Effects of temperature on metabolism and food web structure.(A) Temperature (1/kT for T in Kelvin) dependence of photosynthesis- (PS, slope = −0.32 eV) and respiration- (R, slope = −0.65 eV) based mass-normalized resting metabolic rate (mmol O2/d pg Cαh) (Adapted from Allen et al., 2005 [10], Lopez-Urrutia et al., 2006 [9]). (B) Four possible effects of warming on food web structure and biomass depend on resource availability and the importance of consumer-controlled (CC) or resource-controlled (RC) food web dynamics. Relative size of boxes and ovals indicate standing biomass stocks for the simplest of food webs comprising herbivores (Herb.) and primary producers (P. P.).
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2723928&req=5

pbio-1000178-g001: Effects of temperature on metabolism and food web structure.(A) Temperature (1/kT for T in Kelvin) dependence of photosynthesis- (PS, slope = −0.32 eV) and respiration- (R, slope = −0.65 eV) based mass-normalized resting metabolic rate (mmol O2/d pg Cαh) (Adapted from Allen et al., 2005 [10], Lopez-Urrutia et al., 2006 [9]). (B) Four possible effects of warming on food web structure and biomass depend on resource availability and the importance of consumer-controlled (CC) or resource-controlled (RC) food web dynamics. Relative size of boxes and ovals indicate standing biomass stocks for the simplest of food webs comprising herbivores (Herb.) and primary producers (P. P.).
Mentions: The prevailing conceptual framework for understanding effects of ocean temperature on food webs is based on the view that consumer production is predominantly controlled indirectly by temperature effects on primary production [6],[7]. According to this model, increased primary productivity and net autotrophy also increase CO2 uptake of the whole food web [8],[9]. Yet recently developed metabolic theory and a meta-analysis indicate that heterotrophic (respiration-limited) metabolism is more sensitive to changing temperature than autotrophic (photosynthesis-limited) metabolism and production (Figure 1A) [9],[10], suggesting stronger consumer-driven control with warming. Greater consumer control of primary production would lead to increased heterotrophy and less phytoplankton standing stock (Figure 1B-ii). In either model, the response of food web productivity and structure to changing environmental temperature may be determined by general processes and not the specific responses of component species, and thus could represent a critical step forward in efforts to forecast the impacts of climate change on ecological communities [11],[12].

Bottom Line: Consistent with predictions based on universal metabolic responses to temperature, we found that warming strengthened consumer control of primary production when resources were augmented.Warming shifted food web structure and reduced total biomass despite increases in primary productivity in a marine food web.These results demonstrate that small temperature changes could dramatically shift food web dynamics and provide a general, species-independent mechanism for ecological response to environmental temperature change.

View Article: PubMed Central - PubMed

Affiliation: Curriculum in Ecology, The University of North Carolina, Chapel Hill, Chapel Hill, North Carolina, USA. oconnor@nceas.ucsb.edu

ABSTRACT
Climate change disrupts ecological systems in many ways. Many documented responses depend on species' life histories, contributing to the view that climate change effects are important but difficult to characterize generally. However, systematic variation in metabolic effects of temperature across trophic levels suggests that warming may lead to predictable shifts in food web structure and productivity. We experimentally tested the effects of warming on food web structure and productivity under two resource supply scenarios. Consistent with predictions based on universal metabolic responses to temperature, we found that warming strengthened consumer control of primary production when resources were augmented. Warming shifted food web structure and reduced total biomass despite increases in primary productivity in a marine food web. In contrast, at lower resource levels, food web production was constrained at all temperatures. These results demonstrate that small temperature changes could dramatically shift food web dynamics and provide a general, species-independent mechanism for ecological response to environmental temperature change.

Show MeSH
Related in: MedlinePlus