Plastic accounts for 84% of all litter found on Australian beaches, according to a study conducted by UNSW and based on one of the largest databases of marine debris in the southern hemisphere.
Over 2,000 organizations and 150,000 citizen scientists have participated in the Australian Marine Debris Initiative [AMDI] by sorting and counting the marine debris they have collected since its creation by the association Tangaroa Blue Foundation in 2004.
Now, a study led by UNSW Science has filtered and analyzed 10 years of the AMDI database and created a national map of marine debris patterns.
The study found that nearly half of all debris could be related to land-based sources (garbage and land-based spills) and 7% to marine spills.
But 42% of the debris could not be definitively linked to a source due to the debris breaking down into smaller fragments, which the researchers say highlights the legacy of plastic left in our environment, fragmenting. continually breaking into smaller pieces until they are microplastics.
The results were published in Total environmental science.
“The AMDI database contains beach cleaning entries across Australia, but the added value of this database is that volunteers take the time to categorize what they find, sorting and counting the amounts of plastic. , glass, rubber, metal, paper and others. articles, ”said study lead author and doctoral candidate Jordan Gacutan of the Center for Marine Science and Innovation at UNSW in the School of Biological, Terrestrial and Environmental Sciences.
“We can combine this rich data across space and time to obtain blueprints of the marine debris and plastic problem across Australia.
“This study shows, with unprecedented resolution, the variation of debris elements both regionally and across Australia.”
Study co-author and UNSW Science Dean Professor Emma Johnston says very little environmental stress can be measured nationally.
“So the 150,000 Citizen Scientists who have contributed to this database are doing Australia an incredible service,” says Professor Johnston.
“Their passion for the environment gives us one of the few continental insights into the global marine problem. “
For the AMDI database, the Tangaroa Blue Foundation has developed a method of categorizing and counting all waste collected by a range of citizen scientists and partner organizations, from families to government campaigns.
“We designed the methodology, host it and manage the database, but the data belongs to 150,000 people who contributed to this database,” said Heidi Tait, study co-author and founder and Executive Director of the Tangaroa Blue Foundation.
“This is the impact of the collaboration and the results really underscore that an intervention will not solve the problem of plastics in our oceans, and that a sector or a group of stakeholders will not be able to solve it on their own. , no more. .
“We have to collaborate and this network is a perfect example of partners who have achieved something quite monumental.”
The AMDI database now has nearly 20 million entries, but the UNSW study focused on the 10-year period from which the database recorded beach cleaning nationwide. .
Draw patterns from objects on the beach
Ms Tait said the AMDI database showed that there was a very different signature of marine debris regionally.
“The data shows that what we find in Cape York is completely different from what we find in Port Phillip Bay in Melbourne,” she says.
The UNSW study looked at the national situation, but also grouped its findings according to the six “bioregions” that the Australian government uses to manage our oceans and coasts.
They are: North (Northern Territory to Cape York), Northwest (WA); Southwest (lower WA and SA); Southeast (including Victoria and Tasmania) and temperate (mainly NSW) and Coral Sea / Great Barrier Reef Marine Park.
Mr Gacutan says that by looking at what objects have been found on beaches, we can better understand problematic objects and where they came from.
“Some bioregions contain a large amount of fishing debris, such as floats and fishing nets, while others have a larger litter problem, and you can identify these patterns by the items you find in these. coastal cleanups, ”he says.
The Southeast and Southwest regions have higher amounts of fishing tackle but, on the other hand, the Temperate East had three times the proportion of cigarette butts, compared to the national average, this which shows a problem with local waste, the study suggested.
The study found that around 40% of all marine debris across Australia came from litter, especially near capital cities where a lot of plastic ends up on the beach from storm sewers.
“On the other hand, although Cape York in Queensland had a huge amount of debris, most of it came from external sources, for example floats and plastic bottles that could have been both dropped at sea or floated away. other countries, ”Gacutan said. said.
“We know Cape York is very, very remote, so the amount of plastic we find on the beaches is not due to the people who live there.”
Ms Tait says better evidence needs to be used to inform how we are dealing with the growing problem of marine debris.
“We need to be really focused and strategic in the changes put in place to mitigate marine debris, and we need to measure and monitor to make sure we’re actually fixing the problem, that’s where the data is going to be so critical to the future, ”she says.
Improve citizen science for management
Dr Graeme Clark, lead author of the study and senior research associate at UNSW, said the study focused on filtering the data to ensure it was as accurate and reliable as possible. before use.
“One of the main concerns people have about citizen science data is the quality, accuracy and reliability of the data we get from these cleanings,” he says.
“You get a huge variability in the quality, for example some people can start cleaning the grassy area of a beach or the parking lot; children collect differently from adults; and that really limits comparisons between sites.
“We tried to maximize the quality of the data and control the sites we visited by really conservative filtering.
“We only looked at sandy sites that face the ocean and have not been altered by structures such as dikes and breakwaters.”
Dr Clark says the methods presented by the UNSW team could impact how citizen science databases are used and improve the way marine debris data is collected globally. .
“Improving the quality and rigor of citizen science data makes it easier to use in management and decision-making,” he says.
“Citizen science datasets are powerful tools for monitoring marine debris and can help shape management plans to better tackle the problem of marine debris and plastic pollution at a localized level.”
Ms Tait says the most unique aspect of the AMDI database is that it is based on a scalable model that identifies the source of the debris.
“If you look at what’s going on now internationally with the discussions on global plastics treaties, nationally with the National Plastics Plan and state government plans to tackle single-use plastics: how are we going to measure them to make sure these policies have an impact? ”she said.
“For example, if a global plastics treaty is formalized by the United Nations, we should see the 95% of international marine debris that we find in Cape York diminish in the future, if that treaty is successful.
“It’s a way to measure the impact of the mitigation strategies put in place to see if they are actually having a positive impact and reducing marine debris and litter at the source. “
Read it to study.