The State of the Marine and Coastal Environment 2021 Report highlights the importance of a "catchment to reefs" approach in Victoria. Many of the pressures on our coasts, bays, estuaries, lakes and ocean are derived from our activities on land.

The report tells us that about 80% of marine plastic debris is of land-based origin. More than 2.5 billion pieces of plastic pollution make it to Port Phillip Bay annually, via the surface waters of the Yarra and Maribyrnong Rivers.

The Port Phillip EcoCentre has been researching microplastic pollution (items < 5mm in size)  since 2013. They noted that existing methods for monitoring the increasing volumes of litter entering Port Phillip Bay tended to under-report microplastics. The detrimental effects of microplastics on the environment were becoming established across the world. Yet, the extent of the problem remained unclear in a local context. They designed citizen science methods to measure plastic pollution on streets, in rivers, and on beaches. 

Port Phillip Baykeeper street litter audits were conducted with Scouts Victoria’s Street2Bay project, between 2018 and 2020. They recorded types of litter generated by 6 different suburban street uses. The audits of 127 sites across all Port Phillip Bay catchments found retail sites generated the most litter, followed in order by industrial sites, public buildings, sportsgrounds, parks and residential areas. Of the 54,000 items reordered, 74% were plastic. 

Clean Bay Blueprint

EcoCentre’s Clean Bay Blueprint project established the first ever baseline dataset of microplastic pollution in the Yarra and Maribyrnong Rivers and Port Phillip Bay beaches. This work was completed in partnership with government, citizen scientists and many other partner organisations. 

Microplastics samples were collected as part of monthly river trawls between 2015 and 2020, in partnership with the Yarra Riverkeeper Association. Samples were sorted and counted at the EcoCentre by trained citizen scientists. Volunteer scientists from Monash University and students from the RMIT Plastics Lab then analysed the data. Clean Bay Blueprint’s accomplishments include: 

  • Quantifying microplastic pollution reaching Port Phillip Bay from the Yarra and Maribyrnong Rivers.
  • Determining if the problem is getting better or worse over time. 
  • Establishing a baseline of plastic pollution, which can be used as a benchmark for litter reduction initiatives. 
  • Using results as evidence for positive environmental change, including outcomes such as law changes. 
  • Providing government with a list of six recommendations on how to tackle microplastics and plastic pollution in the local context. 
  • Contributing to ongoing community education by increasing the practical skills of citizen scientists, community science literacy and interest in environmental science.
Port Phillip EcoCentre citizen scientists sorting and counting microplastics from the Yarra River.
Image credit - Port Phillip EcoCentre

Key Facts

  • More than 2.5 billion pieces of plastic pollution make it to Port Phillip Bay annually, via the surface waters of the Yarra and Maribyrnong Rivers. 
  • 85% of this (over 2 billion) are classed as microplastics (plastic pieces smaller than 5 mm in diameter). 
  • 75% of litter reaching the Bay consists of small hard plastic fragments. In second and third place for most recorded items are polystyrene (13%) and soft plastics (10%). 
  • Litter in both rivers has been increasing every year. This is positively correlated with population growth. 
  • The Yarra carries significantly more litter than the Maribyrnong and is getting dirtier at a faster pace.
  • Of all litter items recorded, plastic straws are the only items that have been significantly declining over the last 5.5 years. The EcoCentre believes this is due to community education and local community action campaigns. For example, The Last Straw urges people to refuse plastic straws, and businesses to swap plastic straws for paper ones. The data illustrates that personal behaviour change and community action work. 
  • Volunteers spent 8,800 hours of their time over 3 years supporting this project. This shows that members of the community want to act and be a part of grassroots change. 
  • Volunteers from 16 different countries participated in this project. Many have been able to take knowledge and skills acquired back to their home countries.

The State of the Marine and Coastal Environment 2021 Report contains significant advancement in litter and pollution reporting. It contains a synthesis of the latest microplastics research in Victoria.