Global synthesis reveals systematic variation in trophic transfer efficiency across and within ecosystems

Trophic transfer efficiency (TTE) describes the proportion of energy or nutrients transferred from one trophic level to the next. A common assumption holds that ~10% of energy is transferred upward. This rule of thumb has shaped ecological models and discussions of sustainability, but broad empirical tests are lacking. We compiled 2052 TTE estimates from 122 studies across ecosystems. Average energy transfer efficiency (TTE e ) was 5.92%, well below 10%, while nutrient transfer efficiency (TTE n ) averaged 11.13%. Marine ecosystems had the highest TTE e (8.13%), followed by freshwater (5.53%) and terrestrial (1.52%) systems. TTE e declined with temperature in freshwater and was lower for consumers feeding on autotrophs, endotherms, and higher trophic levels. Our findings challenge long-standing assumptions and highlight the need for better understanding of TTE variation.