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Title: Food webs in freshwater floodplain wetlands inundated with environmental flows during drought conditions.
Authors: Mazumder, D
Johansen, MP
Saintilan, N
Iles, J
Knowles, L
Kobayashi, T
Wen, L
Keywords: Food
Fresh water
Stable isotopes
Issue Date: 9-Aug-2010
Citation: Mazumder, D., Johansen, M., Saintilan, N., Iles, J., Knowles, L., Kobayashi, T., et al. (2010). Food webs in freshwater floodplain wetlands inundated with environmental flows during drought conditions. 7th International Conference on Applications of Stable Isotope Techniques to Ecological Studies (ISOECOL VII), 9th - 13th August 2010. Fairbanks, Alaska: University of Alaska Fairbanks.
Abstract: In the present study we used δS13C and δS15N stable isotope ratios in basal sources, primary producers, and a variety of invertebrate and fish consumers to gain better understanding of the sources of energy and trophic positions for aquatic species at floodplain water bodies within Yanga wetlands, Murrumbidgee floodplain, Australia. We compared δ13C and δ15N data from conditions of higher water levels and volumes that occurred in summer following a managed environmental flow, with data from winter conditions of lower water levels and volumes. Mass-balance mixing models were used to examine relative food source contributions to consumer diet. We also employed probabilistic simulation modelling to better understand trends of trophic positions, diet shifts and varying contributions from sources to consumers in water bodies of the Yanga wetlands. The data indicated contraction in the trophic position of Hypseleotris spp. in winter consistent with shrinking water volumes that induced greater competition, particularly between endemic Hypseleotris spp and and exotic Cyprinus carpio, for overlapping, and more limited varieties of food sources. Data indicated that the δ13C values for fish and insects from the low-water sampling period were typically -2-4%0 depleted compared to the corresponding high-water values. The δ13C values for one basal source (algae) depleted up to 25%0 between the sampling periods, while a second basal source (SOM) depleted less than 4%0. This study provided modelling results that indicated shifts in energy source and trophic position related to water fluctuations were consistent between adjacent water bodies and changes in food availability increased competition among species that may adversely impact population of endemic species.
Gov't Doc #: 3069
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