2022 Early Hearing Detection & Intervention Virtual Conference

March 13 - 15, 2022

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6/05/2017 | 12:15 PM - 12:30 PM | LITTER QUALITY AND STREAM FOOD WEBS: A NEW PARADIGM FOR UNDERSTANDING ELEMENT CYCLING. | 306A

LITTER QUALITY AND STREAM FOOD WEBS: A NEW PARADIGM FOR UNDERSTANDING ELEMENT CYCLING.

Leaf litter quality comprises a suite of chemical and physical traits that influence organic matter cycling through aquatic ecosystems. Differences in litter quality are reflected in decomposition rates with faster decomposing leaves often considered a “higher quality” resource. Decomposition rate, however, provides no information of the pathways of C and N transport from leaves into aquatic food webs. Our experimental findings support a new paradigm for understanding how litter quality affects stream food webs, challenging the view that faster decomposing organic matter is a better food resource. Using labeled leaves (13C and 15N) we demonstrate that leaf types that decompose more slowly (Oak and Sycamore) transfer more of their carbon and nitrogen to insects, whereas faster decomposing leaf types (Broadleaf Cottonwood and Ash) lose significantly more C and N through leaching and microbial processing. Using litter from distinct genotypes of cottonwood trees, we were able to decouple the effects of tannin and lignin on C and N assimilation. Element assimilation correlated positively with lignin concentrations but negatively with tannin concentrations. Across these experiments, the community composition of insects did not differ among leaf types, despite significant differences in biogeochemical pathways.

C10 Biogeochemistry
C25 Food Webs
C31 Organic Matter Processing

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Presenters/Authors

Jane Marks (), Northern Arizona University, jane.marks@nau.edu;