Document Detail

Food-web composition affects cross-ecosystem interactions and subsidies.
MedLine Citation:
PMID:  20584097     Owner:  NLM     Status:  MEDLINE    
1. Ecosystems may affect each other through trophic interactions that cross ecosystem boundaries as well as via the transfer of subsidies, but these effects can vary depending on the identity of species involved in the interaction. 2. In this study, we manipulated two terrestrial bromeliad-living spider species (Aglaoctenus castaneus, Corinna gr. rubripes) that have variable hunting modes, to test their individual and combined effects on aquatic invertebrate community structure and ecosystem processes (i.e. decomposition rate and nitrogen cycling). We predicted that these terrestrial predators can affect aquatic invertebrates and nutrient dynamics within water-filled bromeliads. 3. Aglaoctenus spiders reduced the richness, abundance and biomass of aquatic insect larvae via consumptive or non-consumptive effects on ovipositing terrestrial adults, but effects of the two spider species in combination were usually the linear average of their monoculture effects. In contrast, invertebrates with entirely aquatic life cycles were unaffected or facilitated by spiders. Spiders did not affect either net detritivore biomass or the flux of detrital nitrogen to the bromeliad. Instead, Corinna spiders contributed allochthonous nitrogen to bromeliads. 4. Our results provide the novel observations that predators in one ecosystem not only directly reduce taxa whose life cycles cross-ecosystem boundaries, but also indirectly facilitate taxa whose life cycles are entirely within the second ecosystem. This compensatory response between cross-ecosystem and within-ecosystem taxa may have led to an attenuation of top-down effects across ecosystem boundaries. In addition, our results add to a growing consensus that species identity is an important determinant of community structure and ecosystem functioning. Thus, the composition of both terrestrial and aquatic food webs may affect the strength of cross-ecosystem interactions.
Gustavo Q Romero; Diane S Srivastava
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2010-06-24
Journal Detail:
Title:  The Journal of animal ecology     Volume:  79     ISSN:  1365-2656     ISO Abbreviation:  J Anim Ecol     Publication Date:  2010 Sep 
Date Detail:
Created Date:  2010-08-16     Completed Date:  2010-12-07     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  0376574     Medline TA:  J Anim Ecol     Country:  England    
Other Details:
Languages:  eng     Pagination:  1122-31     Citation Subset:  IM    
Departamento de Zoologia e Botânica, IBILCE, Universidade Estadual Paulista (UNESP), Rua Cristóvão Colombo, 2265, CEP 15054-000, São José do Rio Preto, São Paulo, Brazil.
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MeSH Terms
Food Chain*
Insects / physiology*
Population Dynamics
Predatory Behavior
Spiders / physiology*

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