Stable isotope (δ13C and δ15N) studies in aquatic ecosystems: response to different conditions
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Date
2013-07-10
Journal Title
Journal ISSN
Volume Title
Publisher
The University of Western Australia
Abstract
Rivers and wetlands are complex ecosystems with numerous relationships between water, earth, air, plants and animals. The stable isotopes 13C and 15N were investigated in river and wetland ecosystems to evaluate food web structure complexity, with particular emphasis on their response to changing hydrological conditions. A study developed on the Shoalhaven River focused on assessing the differences in trophic conditions of fish populations found above and below Tallowa Dam. Some species displayed little variation in C or N signatures over the two years sampling period suggesting a preferential dietary niche, regardless of hydrological or density-dependent conditions. The variable diet sources between Australian bass revealed by source mixing calculation also indicated trophic discontinuity within these restricted environments.
We found variable trophic levels and sources for the same species of invertebrate and
fish between habitats in wetlands show the effect of divergent ecological conditions and landuse practices. For example, in the Macquarie Marshes we found that an extended inter-flood interval caused the decline of riparian vegetation communities including river red gum signalling a shift from aquatic floodplain ecosystems to terrestrial ecosystems where grasses and chenopod shrubs dominate as an organic carbon source. Results provide insights into stable isotope use to better understand potential impacts of future climate variation on river and wetland systems.
Description
Keywords
Ecosystems, Isotopes, Hydrology, Invertebrates, Fishes, Wetlands
Citation
Mazumder, D., Walsh, C., Williams, R., Jenkins, K., Sives, C., Hollins, S., Meredith, K., & Doyle, T. (2013). Stable isotope (δ13C and δ15N) studies in aquatic ecosystems: response to different conditions. Paper presented at the 12th Australian Environmental Isotope Conference, 10th-12th July 2013, University of Western Australia, Perth, Australia.