Tracking a century of change in trophic structure and dynamics in a floodplain wetland: integrating palaeoecological and palaeoisotopic evidence

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dc.contributor.authorKattel, G.
dc.contributor.authorGell, P.
dc.contributor.authorPerga, M.
dc.contributor.authorJeppesen, E.
dc.contributor.authorGrundell, R.
dc.contributor.authorWeller, S.
dc.contributor.authorZawadzki, A.
dc.contributor.authorBarry, L.
dc.date.issued2015
dc.description.abstract1. The palaeoecological assessment, and the use of stable isotopes of carbon in subfossils of herbivores and omnivores, represents a novel approach to understand transitions in past food-web structure and the dynamics of lake ecosystems in response to natural perturbations and human impacts. Combined with records of subfossil assemblages of cladocerans and chironomids, it may be possible to decipher whether changes are attributable to external forces or internally derived system shifts. 2. A sediment record taken from the shallow (2.3 m depth) Kings Billabong in the River Murray floodplain (Australia) was analysed to explore changes in trophic dynamics over the past century. 3. The palaeoecological assessment revealed that littoral assemblages of cladocerans and benthic diatoms were gradually replaced by planktonic (planktonic and facultative planktonic) assemblages after river regulation in the 1920s. 4. The stable isotopic composition of carbon (δ¹³C), derived from chironomid head capsules, was relatively constant down-core, ranging between -26.1⁰⁄₀₀ and -24.0⁰⁄₀₀, and coincided largely with the δ¹³C of bulk sediment samples (-25.6⁰⁄₀₀ to -22.0⁰⁄₀₀). The δ¹³C values of pelagic (Daphnia) and ubiquitous (Bosmina, Alona) cladocerans, however, varied markedly, with that for Daphnia between -29.8⁰⁄₀₀ (10–20 cm) and -23.2⁰⁄₀₀ (60–70 cm), and for ubiquitous cladocerans, between -29.4⁰⁄₀₀ (20–30 cm) and -24.5⁰⁄₀₀ (80–70 cm). 5. The temporal changes in the δ¹³C values of cladocerans also suggest a gradual transition from a macrophyte-dominated state to a phytoplankton-dominated state after river regulation and further indicate changes in the horizontal migration behaviour of Daphnia depending on macrophyte abundance and predation risk. 6. Our study demonstrates the potential of reconstructing, more precisely, the trophic dynamics of large river floodplain lakes and their ecological resilience by combining subfossil analyses with stable isotope analyses of selected subfossil groups.
dc.description.statementofresponsibilityGiri Kattel, Peter Gell, Marie-Elodie Perga, Erik Jeppesen, Rosie Grundell, Sandra Weller, Atun Zawadzki and Linda Barry
dc.identifier.citationFreshwater Biology, 2015; 60(4):711-723
dc.identifier.doi10.1111/fwb.12521
dc.identifier.issn0046-5070
dc.identifier.issn1365-2427
dc.identifier.urihttp://hdl.handle.net/2440/92034
dc.language.isoen
dc.publisherWiley
dc.rights© 2014 John Wiley & Sons Ltd
dc.source.urihttp://dx.doi.org/10.1111/fwb.12521
dc.subjectKings Billabong; palaeo-food web structure; River Murray system Australia; stable carbon isotope; subfossil cladocerans and chironomids
dc.titleTracking a century of change in trophic structure and dynamics in a floodplain wetland: integrating palaeoecological and palaeoisotopic evidence
dc.typeJournal article
pubs.publication-statusPublished

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