University Of Tasmania
152575 - Platypus predation has differential effects on aquatic invertebrates in contrasting stream and lake ecosystems.pdf (1.28 MB)
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Platypus predation has differential effects on aquatic invertebrates in contrasting stream and lake ecosystems

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journal contribution
posted on 2023-05-21, 12:23 authored by McLachlan-Troup, TA, Stewart NicolStewart Nicol, Dickman, CR
Predators can have strong impacts on prey populations, with cascading effects on lower trophic levels. Although such effects are well known in aquatic ecosystems, few studies have explored the influence of predatory aquatic mammals, or whether the same predator has similar effects in contrasting systems. We investigated the effects of platypus (Monotremata: Ornithorhynchus anatinus) on its benthic invertebrate prey, and tested predictions that this voracious forager would more strongly affect invertebrates - and indirectly, epilithic algae - in a mesotrophic lake than in a dynamic stream ecosystem. Hypotheses were tested using novel manipulative experiments involving platypus-exclusion cages. Platypuses had strongly suppressive effects on invertebrate prey populations, especially detritivores and omnivores, but weaker or inconsistent effects on invertebrate taxon richness and composition. Contrary to expectation, predation effects were stronger in the stream than the lake; no effects were found on algae in either ecosystem due to weak effects of platypuses on herbivorous invertebrates. Platypuses did not cause redistribution of sediment via their foraging activities. Platypuses can clearly have both strong and subtle effects on aquatic food webs that may vary widely between ecosystems and locations, but further research is needed to replicate our experiments and understand the contextual drivers of this variation.


Publication title

Scientific Reports



Article number







School of Natural Sciences


Nature Publishing Group

Place of publication

United Kingdom

Rights statement

Copyright 2020 the authors. Licensed under Creative Commons Attribution 4.0 International (CC BY 4.0)

Repository Status

  • Open

Socio-economic Objectives

Assessment and management of freshwater ecosystems