2021 State of the Environment Report Marine Chapter – Expert Assessment – Pressure – Marine plastics and debris

The Marine chapter of the 2021 State of the Environment (SoE) report incorporates multiple expert templates developed from streams of marine data. This metadata record describes the Expert Assessment "Pressures on the marine environment - marine plastics and debris". 
<strong><em>A PDF of the full Expert Assessment, including figures and tables (where provided) is downloadable in the "On-line Resources" section of this record as "EXPERT ASSESSMENT 2021 - Marine plastics and debris"</em></strong>



DESCRIPTION OF PRESSURE
Marine debris is recognized as a globally important stressor in the marine environment, with increasing reports of impacts on marine biodiversity reported during the last four decades (Claro et al. 2019; Gall and Thompson 2015) and an estimated 19-23 million metric tons (11% of plastic waste generated in 2016) entering aquatic environments (Borelle et al. 2020). This is an increase from the 6-12 million metric tons of plastic waste estimated to enter the ocean each year (as of 2010) (Jambeck et al. 2015). Furthermore, it is estimated that 1.2-2.4 million metric tonnes of plastic enters the global ocean each year from rivers alone (Lebreton et al. 2017). Marine litter includes consumer items such as glass or plastic bottles, cans, bags, balloons, rubber, metal, fiberglass, cigarettes and other manufactured materials that end up in the ocean and along the coast, and other materials intentionally or unintentionally discarded at sea (UNEP 2009). In Australia, marine debris has been identified as a key threatening process for threatened and endangered vertebrate fauna by the federal Threat Abatement Plan or TAP (Commonwealth of Australia 2018). Marine litter also has socioeconomic impacts, it acts as a transporter of invasive species, can be a navigation hazard and there are increasing concerns over the human health risks due to food security issues from seafood (Rochman et al. 2015). With estimates of ¾ or more of marine debris coming from land-based sources, and continued growth in plastics production and usage, waste leakage is a ubiquitous problem, with high but variable concentrations of marine debris found both in coastal and marine environments (Hardesty et al. 2014). Based on research in the great Australian Bight, it is estimated there is 25 or more times more microplastics alone on the seabed floor than floating on the ocean’s surface, with more than 14 million tonnes of debris across the ocean floor (Barrett et al., 2020). 

DATA STREAM(S) USED IN EXPERT ASSESSMENT
Concentrations derived from a single survey around Australian coastline and at sea, carried out between 2011-2013 as well as data and analyses presented in peer review publications, a recent review of the TAP for marine debris.



2021 SOE ASSESSMENT SUMMARY [see attached Expert Assessment for full details]

• 2021 •
Assessment grade: High impact
Assessment trend: Deteriorating
Confidence grade: Adequate high quality evidence and high level of consensus 
Confidence trend: Adequate high quality evidence and high level of consensus 
Comparability: Grade and trend are comparable to the 2016 assessment 
• 2016 •
Assessment grade: Good
Assessment trend: Stable
Confidence grade: Adequate high quality evidence and high level of consensus
Confidence trend: Adequate high quality evidence and high level of consensus
Comparability: Grade and trend are somewhat comparable to the 2011 assessment
• 2011 •
Assessment grade: Very good
Assessment trend: Stable
Confidence grade: Limited evidence or limited consensus
Confidence trend: Limited evidence or limited consensus



CHANGES SINCE 2016 SOE ASSESSMENT
No change in grade/trend from 2016 assessment.

Tags: anthropogenic pressures, expert assessment, marine debris, marine plastics, pollution
Organization: Australian Ocean Data Network