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Consumption and Secondary Production

Consumption and Secondary Production. Reading: pp. 411-416 (5 th ) A. Food chains and food webs Grazing Detrital (decomposer) B. Energy budget - flow of energy through an ecosystem C. Trophic levels and ecological pyramids D. Efficiency of energy transfer

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Consumption and Secondary Production

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  1. Consumption and Secondary Production Reading: pp. 411-416 (5th) A. Food chains and food webs Grazing Detrital (decomposer) B. Energy budget - flow of energy through an ecosystem C. Trophic levels and ecological pyramids D. Efficiency of energy transfer Consumption, Assimilation, Growth, Secondary production E. How can we determine food web relationships?

  2. Why are big, fierce animals so scarce? Where does the energy come from that fuels ecosystems? What is the fate of that energy? How does it affect the distribution and abundance of organisms of different types?

  3. Simplified food web A. Food chains are simplifications of food webs

  4. B. Energy Budget: Source and fate of energy

  5. ENERGY- Cannot be recycled, flows through ecosystems, from an external source, enters as light exits as heat. MATTER- Cycles within ecosystems. ECOSYSTEM PRINCIPLES 1- Energy flow 2- Chemical cycling (decomposers) Tertiary consumers, etc. Heterotrophs Autotrophs PHOTO, chemo Energy flow and chemical cycling described by grouping species in a community into trophic levels according to main source of nutrition and energy C&R 54.1

  6. B. Energy Budget: Source and fate of energy Points: 1. GPP > NPP > NEP 2. Energy flow is one-way - once used, it is dissipated as heat

  7. C-cycle: the somewhat more detailed version

  8. C. Trophic pyramids Classic food chain 1. Trophic levels: Primary producers, herbivores, carnivores (predators), omnivores, detritivores 2. Rule of thumb: 10% energy transfer between trophic levels

  9. Consequences for diversity

  10. Biomass at each trophic level carnivores herbivores 1o producers Inverted trophic pyramids Can this ever happen with pyramids based on energy flow (productivity)?

  11. D. Efficiencies of energy transfer Why is biomass of animals so small? Where does all the energy go? Why is transfer efficiency so low?

  12. C-cycle: the somewhat more detailed version

  13. Production Respiration Assim. Feces Consumed Assimilated Urine Consumed Unconsumed 1o Prod So, P = C - R - F - U Availability of energy for growth

  14. Trophic energy losses: a Michigan old-field

  15. Production Respiration Assim. Feces Consumed Assimilated Urine Consumed Unconsumed 1o Prod Growth efficiency = P/C = P/A * A/C Availability of energy for growth: Depends on efficiency of transfer Production efficiency = P/A Assimilation efficiency = A/C

  16. Assimilation, production, and growth efficiencies for homeotherms and poikilotherms Smith (1998) Table 11.3, p. 181

  17. Basal metabolic rate – endos & ectos

  18. E. How can we determine food web relationships? • Observation • Gut/feces content • You are what you eat, isotopically speaking.

  19. Fig. 18.20 – Human consumption of corn

  20. Fig. 18.18

  21. Fig. 18.19 – food sources of the ribbed mussel.

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