Estimating anthropogenic debris risk across the NSW Marine Estate

Mr Jordan Gacutan1, Ms Edwina Foulsham2, Dr John Turnbull1, Dr Graeme Clark1

1School of Biological, Earth and Environmental Sciences, University of New South Wales, Kensington, Australia, 2Coastal & Marine Unit, Science Division, Department of Planning, Industry and Environment, NSW Government, Sydney, Australia


The increase in production and use of synthetic materials, such as plastics, will increase the proportion ‘leaking’ into aquatic environments as anthropogenic debris. The increased stock within the environment increases exposure to taxa and biological assemblages, which may lead to determinantal interactions. Whilst the threats (or ‘stressors’) posed to aquatic ecosystems are known in principle, impacts to taxa remain poorly understood. Nevertheless, decision-makers are increasingly required to manage debris and its associated risk, despite limited data.

Within the New South Wales (NSW) Marine Estate, a threat and risk assessment was conducted, addressing knowledge gaps through expert elicitation, to determine the stressors (e.g., entanglement, ingestion, and bioaccumulation) relevant to 8 biological assemblages and identify the items responsible. Estimated values were then used to quantify the risk posed by items per stressor and assemblage, and further linked to existing debris databases to gain a spatial understanding of risk across the marine estate.

Across most biological assemblages, ingestion, entanglement, and bioaccumulation were consistently chosen as prominent stressors by experts. Ingestion and entanglement were related to fishing items, whilst bioaccumulation was related to microplastics and plastic fragments. Spatial trends indicated ‘hotspots’ of risks, in proximity with coastal populations.

The study provides a methodology to overcome knowledge gaps and elicit risk values for items and stressors. By (1) identifying prominent stressors and related items and (2) providing a spatial understanding across the marine estate, managers may better allocate resources and maximise the efficacy of interventions.


As part of his PhD, Jordan works towards understanding marine and coastal debris across Australia and how to best manage the issue with the data available.  He also works in the ocean governance space, as part of the Global Ocean Accounting Partnership.