Session Chairs: Britta Denise Hardesty, CSIRO; Chris Wilcox, CSIRO; Beth Polidoro, Arizona State University

This session provides practitioners, community groups, businesses, government agencies and scientists with different tools and approaches to assess ecological and public health risk from exposure to marine debris, including microplastics.

Understanding plastic pollution from a systems perspective requires a way of conceptualizing sources, distribution and dynamics in the environment; identifying or quantifying impacts on wildlife, humans and other assets; and identifying and evaluating potential management responses. The uncertainties in our knowledge and the difficulty in resolving them satisfactorily can be challenging, given that we are confined to working with largely observational data because experiments at scale are difficult or impossible. To advance our understanding of the risk posed by anthropogenic debris, we suggest applying a conceptual framework that allows us to break the components into smaller parts that not only integrates uncertainty but also connects variables of interest to outcomes in which we are focused.

In a regulatory context, risk assessments are often the first step in developing pollutant regulations, improved resource management, and policies to protect ecological and human health. Given the exponential growth of research and monitoring in marine debris and the potential for toxicological or other adverse impacts, approaches to assess ecological, economic, biodiversity and public health risk are needed to encourage science that can underpin sound policy decision making, as well as to identify critical areas for restoration and research.

The proposed session will bring together a variety of speakers representing academia, government agencies, and conservation organizations to provide a diversity of perspectives, tools and approaches to assessing risk. Topics will include quantitative and qualitative approaches to risk assessment, demonstrated through research and case studies. Methods and tools that are especially useful in data-poor regions will be highlighted, in addition to more refined, or probabilistic methods for use in areas where more data are available.




Why a risk framework for marine debris?

presenting: Britta Denise Hardesty (CSIRO Oceans and Atmosphere, ); authors: Britta Denise Hardesty (CSIRO Oceans and Atmosphere, Australia), Chris Wilcox (CSIRO Oceans and Atmosphere)

Applying a systems perspective to understanding the marine debris issue requires a means of conceptualizing the sources, distribution and dynamics of debris in the environment; identifying or quantifying impacts on wildlife, humans and other assets; and identifying and evaluating potential management responses. There is also a significant degree of uncertainty in our knowledge. Resolving this uncertainty can be challenging, given that we are confined to working with largely observational data because experiments at scale are difficult or impossible. To advance this area of research, we suggest applying a conceptual framework that allows us to break the components into smaller parts that can integrate uncertainty and connect variables of interest to outcomes of interest. We identify four specific questions inherent to a risk framework: the first three focus on risk analysis, and the fourth on risk management or mitigation. In this talk, we present examples that are both data rich and data poor and we discuss the value of integrating a systems perspective, connecting sources and drivers to dynamics and distribution to impacts and management responses. We also discuss the precautionary principle and its application to risk management in the plastics pollution issue.


Risk assessment of plastic pollution on the marine diversity in the Mediterranean Sea

presenting: Monetserrat Compa (Instituto Español de Oceanografía, Spain); authors: Monetserrat Compa (Instituto Español de Oceanografía, Spain), Carme Alomar (Insitituto Español de Oceanografía), Chris Wilcox (Commonwealth Scientific and Industrial Research Organization), Erik van Sebille (Institute for Marine and Atmospheric Research), Laurent Lebreton (The Ocean Cleanup Foundation), Britta Denise Hardesty (Commonwealth Scientific and Industrial Research Organization), Salud Deudero (Instituto Español de Oceanografía)

Plastic marine litter is an increasing threat to marine biodiversity globally and quantifying the impact across different species has so far been complex. This is especially true when combining species with different ecological traits and occupying different ecological niches. Here, we examine the semi-enclosed basin of the Mediterranean Sea where the inputs of marine litter and its impact on the marine diversity are still widely unknown and often are species and location specific. We analyzed 84 species from six taxonomic classes, integrating inter-specific factors such as ingestion rates, biogeography, life history traits (e.g. motility, habitat, and body size) and reference study quality. Species were modeled to spatially identify and estimate their exposure to marine plastic across the Mediterranean Sea by modeling their ingestion rates based on the estimated exposure to plastics. Our models indicate local and regional motility have an impact on the risk of exposure to marine plastic. Body size was also important, regardless of feeding behavior. Overall results from this study indicate coastal species are at higher risks of ingesting plastic in the marine environment. Due to the spatial coverage and species diversity in this study, the results provide an insight into best management practices in coastal hotspot areas to minimize plastic pollution in the marine environment from harming marine wildlife.


Estimating the mortality from plastic ingesation – a new method based on stranding data

presenting: Chris Wilcox (CSIRO Oceans and Atmosphere Business Unit, Australia); authors: Chris Wilcox (CSIRO Oceans and Atmosphere Business Unit, Australia), Qamar Schuyler (CSIRO Oceans and Atmosphere Business Unit), Kathy Townsend (University of Queensland), Melody Puckridge (CSIRO Oceans and Atmosphere Business Unit), Denise Hardesty (CSIRO Oceans and Atmosphere Business Unit)

Plastic in the marine environment is a growing environmental issue. Sea turtles are at significant risk of ingesting plastic debris at all stages of their lifecycle with potentially lethal consequences. We tested the relationship between the amount of plastic a turtle has ingested and the likelihood of death, treating animals that died of known causes unrelated to plastic ingestion as a statistical control group. We utilized two datasets; one based on necropsies of 246 sea turtles and a second using 706 records extracted from a national strandings database. Animals dying of known causes unrelated to plastic ingestion had less plastic in their gut than those that died of either indeterminate causes or due to plastic ingestion directly (e.g. via gut impaction and perforation). We found a 50% probability of mortality once an animal had 14 pieces of plastic in its gut. Our results provide the critical link between recent estimates of plastic ingestion and the population effects of this environmental threat. We discuss extension of this method to cover other species, characteristics of debris, and other key information needs in addressing the threat plastic ingestion poses to wildlife.



presenting: Budi Widianarko (Soegijapranata Catholic University, Indonesia); authors: Budi Widianarko (Soegijapranata Catholic University), Ansje Lohr (Open University of the Netherlands)

A study by Jambeck et al (2015) has indicated that Indonesia is the second largest contributor of mismanaged plastic waste ending up in the ocean. Java, as the most populated island in Indonesia (about 145 million people), contributes 0.116 – 0.145 million tonnes plastics waste per year. This may lead to massive accumulation of microplastics in this coastal area. Seafood from the north coast of Java contained different types of microplastics. Investigation of one strectch of the north coast of Java revealed an alarming result. Our previous research showed that commercial seafood, such as milkfish, mullet, tilapia, blood cockle, and shrimp, contained 3.3 – 7.2 microplastic particles/animal. Microplastic can be considered as a novel food contaminant since it is unintentionally present in food. No safety standard has been set yet for this novel contaminant, and therefore, the qualification of microplastic as a food contaminant is an important first step in food safety based risk assessment. In March 2017, the Indonesian government pledged to reduce marine waste polluting its waters by 70% within eight years. While waiting for this ambitious reduction to take place, the risk for microplastic to enter the food system cannot be omitted and there is a need for an interim regulatory measure. The current absence of regulation regarding microplastic as contaminant in food creates an uncertainty for food safety which has economic consequences. One option to cope with the uncertainty is by setting up a provisional action level. This presentation outlines the derivation steps of the action level based on the principle of unavoidability.


Accumulation of plastic debris and associated contaminants in marine food webs

presenting: Noël Diepens (Wageningen University, Netherlands); authors: Noël Diepens (Wageningen University, Netherlands), Bart Koelmans (Wageningen University)

Plastic debris and their associated contaminants are considered major pollutants of marine systems, yet the extent to which plastics accumulate in food webs remains unclear. Here, we examine the potential for food web accumulation of plastics and associated contaminants on theoretical grounds, using an Integrated Plastic and Contaminant food web Accumulation model (IPCA). The model can be used as a tool for prospective risk assessments, to generate hypotheses that can be verified experimentally and to trigger the further scientific evolution of risk assessment frameworks for marine plastic debris. The model was implemented for an illustrative case: an Arctic foodweb with polar bear as top predator. Furthermore, we provide scenario analyses to investigate the role of (a) plastic and contaminant concentrations, (b) chemical metabolization, (c) plastic and chemical exposure pathway (i.e. bioavailability), and (d) increased plastic emissions in the future, on food web accumulation of plastic and associated chemicals, as expected from existing knowledge and theory.


Assessment of microplastic pollution and ecological risk in Korean coastal waters

presenting: Won Joon Shim (Korea Institute of Ocean Science and Technology, South Korea); authors: Won Joon Shim (Korea Institute of Ocean Science and Technology), Young Kyoung Song (Korea Institute of Ocean Science and Technology), Soeun Eo (Korea Institute of Ocean Science and Technology), Gi Myung Han (Korea Institute of Ocean Science and Technology), Sang Hee Hong (Korea Institute of Ocean Science and Technology)

Horizontal and vertical distribution and composition of microplastics were determined in seawater in along the coast of South Korea in July and August, 2016. Each 100 L of top 20 cm of surface water by grab sampling and mid-water column and bottom water by submerged pump sampling at a station was filtered through a 20-μm mesh net. The volume-reduced water samples were filtered through a 5 μm filter paper and all plastic like particles on the filter papers were identified by spectroscopy using micro-FTIR. The microplastic abundance from six regions was in range of 460-5,480 for surface (n=31), 10-1,060 for middle (n=31) and 30-2,200 particle/m3 for bottom (n=31) water. The mean abundance of plastics from surface waters (1,795±1,276 particle/m3) was significantly higher (p < 0.05) than those in middle and bottom (394±300 and 441±492 particle/m3). Fragment type of microplastics was dominant (77.6-90.5%) and it was followed by fibers. The microplastics less than 300 μm in size accounted for 84% except for fiber type, while in fibers, size < 300 μm only accounted for 28%. The dominant polymer types were polypropylene in both non-fiber (average; 40%) and fiber (average; 95%) in all depth. The environmental levels of >20 μm microplastics in Korean coastal waters were compared with the exposure levels causing adverse biological effects in laboratory toxicity test including the reported values in the literature. Ecological risk was assessed preliminarily with currently available exposure and effect data.