chapter 3 secondary production and consumer energetics © 2013 elsevier, inc. all rights reserved....

Chapter 3Chapter 3

Secondary Production and Consumer Secondary Production and Consumer EnergeticsEnergetics

© 2013 Elsevier, Inc. All rights reserved.From Fundamentals of Ecosystem Science, Weathers, Strayer, and Likens (eds).

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Figure 3.1 Diagram of the consumer energy budget. A=assimilation, E=egestion, I=ingestion, P=production (growth), R=respiration, U=energy contained in nitrogenous compounds in urine.


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Figure 3.2 Four primary determinants of metabolic rates of consumers. (a) Metabolic rates rise with rising temperature and are higher for homeotherms than poikilotherms. (b) Metabolic rates (per unit mass) fall with rising body size. ((a) and (b) redrawn fromPeters 1983.)(c) Metabolic rates may fall over evolutionary time in food-poor habitats. (Data fromGourbault 1972.)


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Figure 3.3 Factors that affect ecological efficiencies. (a, b) Diet: Both assimilation efficiency of marine animals (a) and net growth efficiency of aquatic bacteria (b) increase as diet quality increases. (Redrawn fromValiela 1984anddel Giorgio and Cole 1998.) (c) Temperature: Net growth efficiency of aquatic bacteria falls with rising temperature. (Redrawn fromRivkin and Legendre (2001.) (d) Physiological status: Assimilation efficiency varies across life stages in the crab Menippe mercenaria. (Redrawn from Valiela (1984.)


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Figure 3.4 An example of an empirical model to predict secondary production of individual species of, in this case, marine benthic invertebrates. (a) Estimated versus measured production, showing precision and bias of model results (log10P=0.18+0.97log10B−0.22log10Wm+0.04T−0.014Tlog10(z+1) (P=production, B=mean annual biomass, Wm=individual

body mass, T=temperature, z=water depth). (b) The effect of body size on annual turnover (P/B). (c) Effect of temperature and habitat location on turnover rates (annual P/B), for a species of average biomass (19 g/m2) and large body size (1.2 g dry mass). (Redrawn from Tumbiolo and Downing 1994.)


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Figure 3.5 Production of a guild of consumers often is correlated with the supply rate of its food. (a) Bacterial production as a function of net primary production in various freshwater and marine pelagic ecosystems. (Redrawn fromCole et al. 1988.) (b) Herbivore production in terrestrial ecosystems as a function of net primary production. Dominant herbivores were vertebrates (V) or invertebrates (I). (Redrawn fromMcNaughton et al. 1991.) (c) Production of aquatic insects as a function of leaf litter standing crop in a small Appalachian stream from which litter was experimentally excluded. (d) Production of predatory insects as a function of production of prey insects in the same stream. ((c) and (d) redrawn from Wallace et al. 1999.)


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Figure 3.6 Setting up a whole-stream experiment to exclude inputs of leaf litter from a small stream at the Coweeta Hydrologic Laboratory, North Carolina (some results of this experiment are shown in Figure 3.5). (Photograph by John Hutchens.)


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Figure 3.7 Percentage of net primary production ingested by all herbivores in various aquatic (green symbols) and terrestrial (purple symbols) ecosystems, as a function of nitrogen (a) and phosphorus (b) content of the primary producers. This figure shows that food quality may influence metabolic activity by guilds of consumers. (Redrawn from Cebrian and Lartigue 2004.)


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Figure 3.8 Calculated (a) production, (b) assimilation, and (c) ingestion by the entire community of consumers for a few combinations of net growth efficiency, assimilation efficiency, and ecosystem retentiveness. Production, assimilation, and ingestion are expressed as a percentage of net organic inputs to the ecosystem. Retentiveness is the fraction of organic inputs not subject to nonrespiratory losses (i.e., (S-L)/S). (Modified from Strayer 1988.)


chapter 3 secondary production and consumer energetics © 2013 elsevier, inc. all rights reserved....

Documents

function of production

production growth

b herbivore production

measured production

bacterial production

b assimilation

ecosystem retentiveness

b metabolic rates