Document Type

Article

Publication Version

Version of Record

Publication Date

2-2013

Departmental Paper Identifier

NRM-74

Keywords

alternative stable states, common carp, Cyprinus carpio, decomposition, disturbance, eutrophication, food webs, Midwest, nutrients, pulse, shallow lake, subsidy

Abstract

Resource pulses and subsidies can supply ecosystems with an important source of nutrients that supports additional productivity at multiple trophic levels. Common carp Cyprinus carpio provide ecosystems with a continuous nutrient subsidy through bioturbation and excretion but may also initiate a nutrient pulse through carcass decomposition. We examined how continuous (common carp foraging and excretion), pulsed (carcass decomposition) and disrupted (carp introduced and then removed) nutrient subsidies differed in their ability to alter nutrient availability, ecosystem productivity and stability and energy flow. Nitrogen and phosphorus availability and primary production were highest in pulsed, intermediate in continuous and lowest for disrupted and control systems. Continuous, and to a lesser extent pulsed, systems were associated with decreased water clarity and macrophyte coverage. Nutrient pulses ascended to higher trophic levels and supported greater densities of consumers (i.e., zooplankton and macroinvertebrates). Biotic and abiotic responses in disrupted systems quickly returned to control levels and water quality improved. Light penetration and Daphnia spp. dynamics were more stable in systems with pulses whereas stability of other variables was similar across treatments. Biotic materials collected from pulsed and continuous subsidy systems were typically enriched in δ15N suggesting common carp-derived nutrients supported increased productivity whereas δ13C signatures were depleted suggesting a transition to more pelagic energy pathways, likely due to enhanced phytoplankton production. Our results suggest that continuous and pulsed nutrient subsidies vary in their ability to support and sustain ecosystem productivity with resulting variation in food web structure and ecosystem stability.

Publication Title

Ecosphere

Volume

4

Issue

2

Pages

13

Format

application/pdf

Language

en

DOI of Published Version

10.1890/ES12-00354.1

Publisher

Ecological Society of America

Rights

Copyright © Weber and Brown.

Creative Commons License

Creative Commons Attribution 3.0 License
This work is licensed under a Creative Commons Attribution 3.0 License.

Comments

This work was published in Ecosphere (2013) 4(2):27

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