Types, sources and at‐sea distribution of marine debris in Australian waters
Marine Debris is an increasing issue for the integrity of marine ecosystems in Australia, with reports of impacts on wildlife ranging from entanglement and drowning to increased transport of pollutants into food chains.
Researchers have identified some animal populations that are heavily impacted by marine debris, including several species of turtle in the northern and eastern marine bioregions, and seabirds nesting on some offshore islands. Impacts are in the form of ingestion or entanglement, and may result in reduced health, decreased reproductive output and mortality.
Developing a synoptic understanding of the overall threat to ecological systems has been difficult. This uncertainty has been due to three causes: an absence of a national map of the distribution of marine debris, comparative information on exposure of wildlife across taxa and regions, and a clear understanding of the effects of exposure to debris. This project provided an initial step in addressing this uncertainty by identifying available information on debris and developing preliminary analysis of its sources and distribution at a national scale.
We collated information from various marine debris monitoring sites across the country in order to identify and understand the available data, and then to used it to describe the types of marine debris that wash up on shore at selected sites. Next, we chose four sites that would be geographically representative and which had good quality monitoring data. For each of these sites we used ocean drift models to predict the likely paths of debris arriving at these sites to understand the potential sources of the debris.
Then, we investigated the likely domestic versus foreign contribution to debris in the Australia marine estate by modelling the likely paths of debris emanating from major domestic population centres, and from selected locations at the boundary of the Australian Exclusive Economic Zone.
Finally, to understand how the characteristics of debris might affect their movement and distribution we analysed the effect of wind and surface currents in the movement of debris, and the variation in these effects among years and seasons. This analysis provides some information on how sources different types of debris might vary.