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Behavioural responses of platypuses to desedimentation works in the Blue Lake at Jenolan Karst Conservation Reserve, New South Wales, with notes on the relationship between platypus occurrence and habitat variables in nearby streams

Anne Musser , Eren Turak , Tom Grant

Abstract

Instream earthworks occur in many streams in Australia – often following damage by flooding – to rehabilitate stream banks, remove flood-generated debris or protect against future flood damage. Earthworks may unavoidably disturb habitat, and understanding how species respond to such disturbance is critical to long-term conservation. We report the responses of platypuses to major instream works in the Blue Lake, upper Jenolan River, following severe catchment erosion and flooding in February 2020 and March 2021. Platypuses continued to use the lake during the works in 2020, but were observed or detected by remote cameras, moving into or out of the Blue Lake, less often as the works progressed, returning quickly on works completion and lake refilling. During later works in 2022, platypuses were only seen in the Blue Lake or detected by remote cameras for a few days after the start of the works, returning more slowly than in 2020, but indicating persistent long-term use of the Blue Lake despite these major instream works. Our analysis of available platypus occurrence data, macroinvertebrate and benthic substrate data highlights the importance of coarse benthic substrates associated with platypus occurrence in other streams in the Greater Blue Mountains World Heritage Area, suggesting potential benefits of targeted benthic substrate rehabilitation following such instream works.

AM24035  Accepted 17 April 2025

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