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Can C4 plants contribute to aquatic food webs of subtropical streams?

Citation

Clapcott, J and Bunn, SE, Can C4 plants contribute to aquatic food webs of subtropical streams?, Freshwater Biology, 48, (6) pp. 1105-1116. ISSN 0046-5070 (2003) [Refereed Article]

DOI: doi:10.1046/j.1365-2427.2003.01077.x

Abstract

1. Recent stable isotope studies have revealed that C4 plants play a minor role in aquatic food webs, despite their often widespread distribution and production. We compared the breakdown of C3 (Eucalyptus) and C4 (Saccharum and Urochloa) plant litter in a small rain forest stream and used laboratory feeding experiments to determine their potential contribution to the aquatic food web. 2. All species of litter broke down at a fast rate in the stream, although Urochloa was significantly faster than Eucalyptus and Saccharum. This was consistent with the observed higher total organic nitrogen of Urochloa compared with the other two species. 3. The breakdown of Urochloa and Saccharum was, however, not associated with shredding invertebrates, which were poorly represented in leaf packs compared with the native Eucalyptus. The composition of the invertebrate fauna in packs of Urochloa quickly diverged from that of the other two species. 4. Feeding experiments using a common shredding aquatic insect Anisocentropus kirramus showed a distinct preference for Eucalyptus over both C4 species. Anisocentropus was observed to ingest C4 plant litter, particularly in the absence of other choices, and faecal material collected was clearly of C4 origin, as determined by stable isotope analysis. However, the stable carbon isotope values of the larvae did not shift away from their C3 signature in any of the feeding trials. 5. These data suggest that shredders avoid the consumption of C4 plants, in favour of native C3 species that appear to be of lower food quality (based on C:N ratios). Lower rates of consumption and lack of assimilation of C4 carbon also suggest that shredders may have a limited ability to process this material, even in the absence of alternative litter sources. Large scale clearing of forest and vegetation for C4 crops such as sugarcane will undoubtedly have important consequences for stream ecosystem function.

Item Details

Item Type:Refereed Article
Research Division:Biological Sciences
Research Group:Ecology
Research Field:Freshwater Ecology
Objective Division:Environment
Objective Group:Land and Water Management
Objective Field:Land and Water Management of environments not elsewhere classified
Author:Clapcott, J (Ms Joanne Clapcott)
ID Code:26291
Year Published:2003
Web of Science® Times Cited:38
Deposited By:Zoology
Deposited On:2003-08-01
Last Modified:2004-12-06
Downloads:0

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