Pusey, Bradley J., Kennard, Mark, Beesley, Leah S., Ho, Tsz Wai, Davis, Aaron M., and Douglas, Michael M. (2025) Eating In or Out? Terrestrial Contributions to the Diet of Australian Freshwater Fish. Freshwater Biology, 70 (11). e70129.

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Abstract

1. Intact riparian vegetation plays an important role in the energetics of freshwater ecosystems. Plant and animal biomass from the riparian zone may be directly consumed by freshwater organisms without intermediary processing by microbial or metazoan communities. This study examined the extent and importance of such direct consumption by Australian freshwater fishes.

2. We assembled a data set that spanned the Australian continent and examined the extent of terrestrial contributions to freshwater fish diets for 137 species (i.e., approximately one half of Australia's fish fauna). Using a range of multivariate methods we examined variation in reliance on terrestrial material (leaves, fruit, invertebrates and vertebrates) between species and families and between different regions of Australia, particularly focussing on differences between temperate and tropical Australia. We also examined whether particular aspects of morphology were related to increased consumption of terrestrially-derived material.

3. Overall, terrestrial invertebrates contributed 10% or more of the diet of about one quarter of all species and families examined. Most families contained at least one species for which consumption of terrestrial invertebrates was high (> 20%) but only two families, Galaxiidae and Melanotaeniidae, exhibited consistently high consumption across most species. Terrestrial vegetation, principally fruit, contributed 10% or more of the diet in three species from two families only (Terapontidae and Ariidae). There was little regional variation in reliance on terrestrial invertebrates as a food source, but species in south-western Western Australia consistently consumed more than did species elsewhere. Frugivory, in contrast, was significantly more common in the wet-dry tropical northern Australia as reported elsewhere for other tropical regions.

4. Australian freshwater fishes appear to rely more on terrestrial invertebrates than do freshwater fishes elsewhere although data is largely lacking to make broader comparisons with other continents. Morphological correlates with the consumption of terrestrial material were individually and collectively limited, but species with a pelagic habit and an upturned (supraterminal) mouth consumed significantly more such material than did species within other habit/mouth orientation combinations.

5. The present study further confirms the importance of the riparian zone to lotic ecosystem function with direct contributions of terrestrially derived material contributing significantly to the diet of many species and of some families in particular.

Item ID:	91070
Item Type:	Article (Research - C1)
ISSN:	1365-2427
Keywords:	allochthony, food webs, ichthychory, riparian, subsidy
Copyright Information:	© 2025 John Wiley & Sons Ltd.
Date Deposited:	31 Mar 2026 02:22
FoR Codes:	41 ENVIRONMENTAL SCIENCES > 4104 Environmental management > 410402 Environmental assessment and monitoring @ 50% 41 ENVIRONMENTAL SCIENCES > 4104 Environmental management > 410404 Environmental management @ 50%
SEO Codes:	18 ENVIRONMENTAL MANAGEMENT > 1803 Fresh, ground and surface water systems and management > 180301 Assessment and management of freshwater ecosystems @ 50% 18 ENVIRONMENTAL MANAGEMENT > 1803 Fresh, ground and surface water systems and management > 180306 Measurement and assessment of freshwater quality (incl. physical and chemical conditions of water) @ 50%
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