Determining the associated risk of beach-washed logs and their origin at Milman Island, a nesting ground for the endangered hawksbill turtle (Eretmochelys imbricata)

Abstract

Globally, beach-washed logs have been shown to negatively affect marine turtle nesting, but the effects and origin of beach-washed logs on remote beaches in Australia have not yet been investigated. This study presents a novel investigation into the species and origin of timber logs washed ashore on an endangered marine turtle nesting beach at Milman Island, in the Great Barrier Reef, and their potential impact on nesting attempts. A spatial analysis of the coincidence of beach-washed logs and nesting attempts highlighted several areas around Milman Island that should be prioritised for future action to remove high-impact logs. Probable log origin was determined by tree species analysis and validated through ocean current modelling. This indicated that timber species found on Milman Island had a probable origin in the Coral Sea, including Papua New Guinea and the Solomon Islands. Manipulative experiments involving the presence or absence of beach-washed logs could be the next step in further understanding the relationship between the nesting behaviour of the Eretmochelys imbricata population on Milman Island and beach-washed logs.