2023 Early Hearing Detection & Intervention Conference

March 5-7, 2023 • Cincinnati, OH

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5/21/2018 | 11:15 AM - 11:30 AM | ISOSCAPES REVEAL CRITICAL SOURCE AREAS SUSTAINING FLOODPLAIN RIVER FISH ASSEMBLAGES IN NORTHERN AUSTRALIA | 420 A

ISOSCAPES REVEAL CRITICAL SOURCE AREAS SUSTAINING FLOODPLAIN RIVER FISH ASSEMBLAGES IN NORTHERN AUSTRALIA

Many animal populations are controlled by fluxes of energy and nutrients from outside of the habitats they occupy. However, the strength of these subsidies can vary as a consequence of fluctuations in food abundance or the ability of mobile consumers to track food resources. We used sulfur and carbon isotopes to map foraging isoscapes for aquatic consumers across two adjacent floodplain rivers in tropical northern Australia, and modelled the likelihood that a consumer derived its biomass from the location it was sampled or from elsewhere. Small bodied fish species showed a close association with local food resources, in both wet and dry seasons. However, larger mobile species appeared to be dependent on access to specific locations within inundated floodplains for much of their somatic growth. These tended to be deeper areas that retain open water and submerged macrophytes, which support high epiphyte growth. Changes to flow regimes that diminish the depth or duration of inundation of these ‘hotspots’ of high quality food resources, or the presence of barriers that restrict access of mobile consumers to them, are likely to significantly reduce this important floodplain subsidy to river food webs.

Isotope
Floodplain
Subsidy

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Presenters/Authors

Fernanda Adame (), Australian Rivers Institute, Griffith University, f.adame@griffith.edu.au;