Quantity and quality limit detritivore growth: mechanisms revealed by ecological stoichiometry and co-limitation theory

Ecology. 2017 Dec;98(12):2995-3002. doi: 10.1002/ecy.2026. Epub 2017 Oct 18.


Resource quantity and quality are fundamental bottom-up constraints on consumers. Best understood in autotroph-based systems, co-occurrence of these constraints may be common but remains poorly studied in detrital-based systems. Here, we used a laboratory growth experiment to test limitation of the detritivorous caddisfly larvae Pycnopsyche lepida across a concurrent gradient of oak litter quantity (food supply) and quality (phosphorus : carbon [P:C ratios]). Growth increased simultaneously with quantity and quality, indicating co-limitation across the resource gradients. We merged approaches of ecological stoichiometry and co-limitation theory, showing how co-limitation reflected shifts in C and P acquisition throughout homeostatic regulation. Increased growth was best explained by elevated consumption rates and improved P assimilation, which both increased with elevated quantity and quality. Notably, C assimilation efficiencies remained unchanged and achieved maximum 18% at low quantity despite pronounced C limitation. Detrital C recalcitrance and substantive post-assimilatory C losses probably set a minimum quantity threshold to achieve positive C balance. Above this threshold, greater quality enhanced larval growth probably by improving P assimilation toward P-intensive growth. We suggest this interplay of C and P acquisition contributes to detritivore co-limitation, highlighting quantity and quality as potential simultaneous bottom-up controls in detrital-based ecosystems, including under anthropogenic change like nutrient enrichment.

Keywords: Pycnopsyche lepida; assimilation; consumption; detritus; headwater streams; multiple resources; response surface; subsidies.

MeSH terms

  • Animals
  • Carbon
  • Ecology
  • Ecosystem*
  • Feeding Behavior*
  • Insecta / physiology*
  • Phosphorus


  • Phosphorus
  • Carbon