2023 Early Hearing Detection & Intervention Conference

March 5-7, 2023 • Cincinnati, OH

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5/20/2019 | 2:00 PM - 2:15 PM | EXPERIMENTAL N AND P ADDITIONS RELIEVE STOICHIOMETRIC CONSTRAINTS ON ORGANIC-MATTER FLOWS THROUGH FIVE STREAM FOOD WEBS | 250 DE

EXPERIMENTAL N AND P ADDITIONS RELIEVE STOICHIOMETRIC CONSTRAINTS ON ORGANIC-MATTER FLOWS THROUGH FIVE STREAM FOOD WEBS

Pervasive nutrient pollution is changing basal resource quality in food webs, thereby affecting rates and pathways of energy and material flow to higher trophic levels. We used the framework of ecological stoichiometry to investigate the effects of experimental N and P enrichment on the trophic basis of macroinvertebrate production and flows of dominant food resources to consumers in five headwater streams (target N:P of 2:1 to 128:1). Nutrient enrichment resulted in increased basal resource flows to consumers relative to reference conditions, with the greatest increases occurring among resources that experienced the largest reductions in C:P ratios. Flows of leaf detritus, diatoms and wood were all negatively related to resource C:P, indicating widespread P-limitation in these detritus-based food webs. However, increased basal resource flows did not uniformly result in greater material flows to predators. Invertebrates consumed a greater proportion of available leaf litter following nutrient enrichment, with that proportion increasing with decreasing leaf litter C:P. This study suggests that global increases in N and P supply will increase organic matter flows to consumers in detritus-based ecosystems by reducing stoichiometric constraints at the base of food webs.

Food Webs
Stoichiometry
Nitrogen

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Presenters/Authors

Lee Demi (), North Carolina State University, mickdemi@yahoo.com;