Trophic Efficiency Calculators

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Trophic efficiency is the fraction of energy or production at one trophic level that is transferred to the next higher trophic level. Also called ecological efficiency or Lindeman's efficiency, it averages approximately 10% — meaning that only 10% of the energy available at one trophic level reaches the next. The remaining 90% is lost to respiration, feces, excretion, and non-consumed biomass. This 10% rule determines the maximum number of trophic levels a food chain can support, explains why top predators are rare relative to producers, and has implications for human food choices (plant-based diets are more energy-efficient than meat-based diets).

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Trophic Efficiency Formula

TE = (Production at level n+1) / (Production at level n) × 100%

Or equivalently: TE = (Ingestion at level n+1) / (Ingestion at level n) × 100%. Average TE ≈ 10% (range 5–20%). Example: 1000 g C/m²/yr of plant production → ~100 g/m²/yr herbivore production → ~10 g/m²/yr carnivore production → ~1 g/m²/yr top predator production.

Components of Energy Loss

  • Respiration (largest): Energy used for metabolism, thermoregulation, movement; 50–90% of assimilated energy for endotherms
  • Non-assimilation (feces): Ingested food not absorbed across gut wall; 10–40% for herbivores (plant cell walls resist digestion); < 10% for carnivores (animal tissue easily digested)
  • Non-consumed biomass: Organisms that die without being eaten; contributes to detritus food chain

Why Endotherms Are Less Efficient

Endotherms (birds, mammals) devote 80–90% of assimilated energy to thermoregulation → production efficiency 1–5%. Ectotherms (fish, insects) devote minimal energy to temperature regulation → production efficiency 10–50%. This is why aquaculture (fish, shrimp) requires far less feed per kg protein than poultry or beef.

Implications

Food chains are short (2–5 levels) because energy limits higher levels. Human diet: shifting from beef (≈3% trophic efficiency) to poultry (≈10%) to fish (≈10%) to plant foods (~100% trophic efficiency within the human food system) dramatically reduces the land, water, and energy needed per calorie consumed.

Glossary

Trophic Efficiency
Energy transferred to trophic level n+1 as a fraction of energy at level n; ~10% average (Lindeman's rule); determines food chain length and the rarity of top predators.
Production Efficiency (PE)
Assimilated energy converted to new biomass: PE = production/assimilation × 100%; 1–5% for endotherms (high respiration cost); 10–50% for ectotherms (minimal thermoregulation cost).
Lindeman's 10% Rule
The approximation that ~10% of energy/biomass at each trophic level is transferred to the next; actual values range 5–20%; explains why food chains are short and top predator biomass is low.

Frequently Asked Questions

Trophic efficiency = energy at trophic level n+1 / energy at level n × 100%. The ~10% average (Lindeman's 10% rule) reflects multiple energy loss pathways: (1) Respiration — the dominant loss; organisms use most assimilated energy for metabolic maintenance, movement, and thermoregulation. (2) Feces — food not absorbed. (3) Non-consumed biomass — organisms that die without being eaten; this enters the detritus pathway. Only the fraction that becomes new biomass (production) is available to the next trophic level. Actual efficiencies range 5–20% depending on taxon, ecosystem, and conditions.

Trophic efficiency (TE) = energy flux at level n+1 / energy flux at level n — measures transfer across trophic boundaries; includes both ingestion and assimilation efficiencies. Production efficiency (PE) = production / assimilation × 100% — measures how much assimilated energy becomes new biomass within a trophic level; 1–5% for endotherms, 10–50% for ectotherms. Trophic efficiency = assimilation efficiency × production efficiency × exploitation efficiency (fraction of production consumed by the next level). Distinguishing these components helps understand whether energy loss occurs primarily in digestion (low AE), metabolism (low PE), or non-consumption (low exploitation).

At 10% efficiency, each trophic level has 1/10 the energy of the level below it. Starting with 10,000 kcal/m²/yr at producers: herbivores get 1,000; primary carnivores get 100; secondary carnivores get 10; tertiary predators get 1 kcal/m²/yr. This explains why most food chains have only 3–5 trophic levels — there is insufficient energy to support additional levels above the top predators. The higher the trophic level, the lower the biomass density, the larger the home range per individual, and the lower the population size. Lions, killer whales, and polar bears are consequently rare relative to their prey.

Each step up a food chain loses ~90% of energy. For human food: eating plants directly uses energy most efficiently; eating herbivores (cattle, sheep) involves one step of 10% efficiency; eating carnivorous fish involves two or more steps. Feed conversion ratios: cattle ~8 kg feed/kg beef; pork ~3–4 kg/kg; poultry ~2 kg/kg; farmed salmon ~1.3 kg/kg (because salmon is fed partly plant-based feed now). Plant-based protein requires the least land, water, and energy per unit of human nutrition. This thermodynamic reality underlies the environmental argument for reducing meat consumption in high-income countries.