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Presented at the NABS Annual meeting, Pittsburgh, Pennsylvania, 2002
in Food Webs I
RELATIVE IMPORTANCE OF ALLOCHTHONOUS AND AUTOCHTHONOUS CARBON TO LITTORAL ZONE FOOD WEBS IN FIVE PERCHED DUNE LAKES ON FRASER ISLAND, AUSTRALIA.
W.L. Hadwen1, S.E. Bunn1, A.H. Arthington1, and T.D. Mosisch2. 1Centre for Catchment and In-Stream Research and Cooperative Research Centre for Sustainable Tourism, Griffith University, Nathan, QLD 4111, Australia, 2South Australian Water Corporation GPO Box 1751, Adelaide, SA 5001, Australia
Stable isotope techniques were used to determine the relative importance of allochthonous and autochthonous sources of carbon to littoral zone food webs in five perched dune lakes on Fraser Island Australia. Samples of riparian vegetation, particulate organic matter (POM), reeds, and periphyton had consistent δ13C values across all lakes, with POM signatures generally mirroring those of riparian vegetation. Periphyton δ13C signatures were less depleted than those of reeds, POM, and riparian vegetation, respectively, enabling comparisons of the relative contributions of each of these carbon sources to littoral zone food webs in each lake. Primary and secondary consumers from two of the five lakes had δ13C values within the range of values for riparian vegetation (and POM), whilst the less depleted δ13C signatures of consumers in the other lakes indicated that periphyton was a much more significant carbon source. Since periphyton biomass can be affected by nutrient inputs from tourists in these oligotrophic systems, the long-term consequences of cultural eutrophication will ultimately be determined by the relative dominance of allochthonous and autochthonous energy pathways in each lake.
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