Document Detail


Dual influences of ecosystem size and disturbance on food chain length in streams.
MedLine Citation:
PMID:  20482579     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
The number of trophic transfers occurring between basal resources and top predators, food chain length (FCL), varies widely in the world's ecosystems for reasons that are poorly understood, particularly for stream ecosystems. Available evidence indicates that FCL is set by energetic constraints, environmental stochasticity, or ecosystem size effects, although no single explanation has yet accounted for FCL patterns in a broad sense. Further, whether environmental disturbance can influence FCL has been debated on both theoretical and empirical grounds for quite some time. Using data from sixteen South Island, New Zealand streams, we determined whether the so-called ecosystem size, disturbance, or resource availability hypotheses could account for FCL variation in high country fluvial environments. Stable isotope-based estimates of maximum trophic position ranged from 2.6 to 4.2 and averaged 3.5, a value on par with the global FCL average for streams. Model-selection results indicated that stream size and disturbance regime best explained across-site patterns in FCL, although resource availability was negatively correlated with our measure of disturbance; FCL approached its maximum in large, stable springs and was <3.5 trophic levels in small, fishless and/or disturbed streams. Community data indicate that size influenced FCL, primarily through its influence on local fish species richness (i.e., via trophic level additions and/or insertions), whereas disturbance did so via an effect on the relative availability of intermediate predators (i.e., predatory invertebrates) as prey for fishes. Overall, our results demonstrate that disturbance can have an important food web-structuring role in stream ecosystems, and further imply that pluralistic explanations are needed to fully understand the range of structural variation observed for real food webs.
Authors:
Peter A McHugh; Angus R McIntosh; Phillip G Jellyman
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2010-05-12
Journal Detail:
Title:  Ecology letters     Volume:  13     ISSN:  1461-0248     ISO Abbreviation:  Ecol. Lett.     Publication Date:  2010 Jul 
Date Detail:
Created Date:  2010-07-19     Completed Date:  2010-10-21     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  101121949     Medline TA:  Ecol Lett     Country:  England    
Other Details:
Languages:  eng     Pagination:  881-90     Citation Subset:  IM    
Affiliation:
Freshwater Ecology Research Group, School of Biological Sciences, University of Canterbury, Private Bag 4800, Christchurch, New Zealand. pete.mchugh@canterbury.ac.nz
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MeSH Terms
Descriptor/Qualifier:
Animals
Ecosystem*
Food Chain*
Fresh Water*
New Zealand

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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