Hostname: page-component-7c8c6479df-ph5wq Total loading time: 0 Render date: 2024-03-27T20:08:48.927Z Has data issue: false hasContentIssue false

A stable isotope study of a neotropical stream food web prior to the extirpation of its large amphibian community

Published online by Cambridge University Press:  29 October 2007

Piet Verburg
Affiliation:
Institute of Ecology, University of Georgia, Athens, GA 30602, USA
Susan S. Kilham
Affiliation:
Department of Bioscience and Biotechnology, Drexel University, 3141 Chestnut, Philadelphia, PA 19104, USA
Catherine M. Pringle
Affiliation:
Institute of Ecology, University of Georgia, Athens, GA 30602, USA
Karen R. Lips
Affiliation:
Department of Zoology, Southern Illinois University, Carbondale, IL 62901-6501, USA
Dana L. Drake
Affiliation:
Institute of Ecology, University of Georgia, Athens, GA 30602, USA Present address: Public Lands Institute, University of Nevada, Las Vegas, 4505 Maryland Parkway, Las Vegas, NV 89154, USA.

Abstract

Rapid and massive amphibian population declines have been reported throughout upland areas of the Neotropics. The abundance and species richness of Neotropical amphibian communities suggest that losses of this magnitude are likely to have strong effects at the ecosystem level. To improve understanding of the implications of their loss we used stable isotope analysis to examine trophic relationships in an ecosystem in which amphibians are dominant in a second-order forest stream at 750 m asl in Parque Nacional Omar Torrijos Herrera, Panama. We analysed δ13C, δ15N and C:N ratios of major biotic components (basal resources, invertebrates, amphibians, fish and reptiles) in the stream and of the adjacent riparian food web. Tadpoles (mean δ15N = 4.49‰) and adult amphibians (mean δ15N = 5.45‰) were intermediate links in the aquatic and terrestrial food web respectively. High δ15N signatures identified fish as top predators in the aquatic food web and snakes and the toad Bufo as top predators in the terrestrial food web. Isotopic signatures clearly distinguished between trophic groups of tadpoles: microbial feeders (Centrolenidae, δ15N range = 0.91–3.05‰), herbivores (Rana and Hyla, δ15N range = 4.74–5.15‰) and neuston feeders (Colostethus, δ15N range = 5.31–6.40‰). Dependence on autotrophic production was indicated by enriched signatures of carbon isotopes in pool dwellers versus those that reside in faster-flowing sections of the stream. High nitrogen concentrations in detrital matter (average 0.8%, C:N = 10.3) suggested that grazing tadpoles enhanced nitrogen fluxes and improved the quality of organic matter available to detritivores.

Type
Research Article
Copyright
2007 Cambridge University Press

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)