Trophic downgrading results in complex ecosystem dynamics in experimental tropical floodplain food webs

Richard Pendleton, David J. Hoeinghaus, Luiz C. Gomes, Angelo A. Agostinho

Research output: Contribution to journalArticlepeer-review

Abstract

Species or functional guild loss from upper trophic positions, i.e., trophic downgrading, will likely have important consequences for ecosystem functioning due to cascading direct and indirect effects. Using 1000 l mesocosms, we examined how sequential loss of species occupying upper trophic positions influenced ecosystem functioning of experimental floodplain lagoon food webs. Treatments were developed based on fish assemblage data from long-term field surveys of tropical floodplain lagoons, and response variables represented multiple components of ecosystem functioning. Sequential loss of species occupying upper trophic positions significantly influenced multiple ecosystem responses including changes in fish assemblage structure, nutrient concentrations, and zooplankton density. Although loss of species from specific functional roles is expected to facilitate predictive understanding of ecosystem consequences, we observed complex and dynamic responses to trophic downgrading that did not follow expectations of strong predicted top-down effects. The highly connected food web structure in our system and relative balance between top-down and bottom-up processes likely suppressed cascading effects. Consequences of biodiversity loss in highly connected multitrophic ecosystems may be difficult to predict as ecosystem responses will likely deviate from simplified food chain dynamics or from patterns that emerged from single trophic level studies.

Original languageEnglish (US)
Pages (from-to)15-28
Number of pages14
JournalHydrobiologia
Volume760
Issue number1
DOIs
StatePublished - Nov 25 2015

Keywords

  • Biodiversity loss
  • Ecosystem function
  • Multifunctionality
  • Species richness
  • Trophic position

ASJC Scopus subject areas

  • Aquatic Science

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