Plastic rubbish can be found almost everywhere and currently, broken-down microplastics have been discovered in variable concentrations in blue mussels and water inside the intertidal zone at a few of the most famous and highly remote beaches in southern Australia.
Map of South Australian coastline and 10 survey sites – Shelly Bay, Ceduna; Black Springs, Coffin Bay; Main Beach, Port Lincoln; Point Lowly, Whyalla; Semaphore Beach, Adelaide; Hallett Cove Beach, Adelaide; Blowhole Beach, Deep Creek; Encounter Bay, Victor Harbor; Karrata Beach, Robe; and, Brown's Beach, Kangaroo Island. (Courtesy Claire Moore). Image Credit: Flinders University.
Researchers from Flinders University warn that this could mean that microplastics are currently making their way into human food supplies. This includes wild-caught and ocean-farmed fish and seafood obtained from the once pristine Southern Ocean and gulf waters of South Australia.
Our findings shed light on the urgent need to prevent microplastic pollution by working with the communities, industries, and government to protect these fragile marine systems.
Karen Burke da Silva, Study Senior Author and Professor, Flinders University
The new study has been reported in the Science of the Total Environment journal.
The research group from the Flinders University sampled different levels of microplastics on 10 famous beaches throughout South Australia, from Coffin Bay and Port Lincoln on the West Coast to Point Lowly and Whyalla on the Spencer Gulf to famous Adelaide metropolitan beaches such as Victor Harbor, Robe and Kangaroo Island.
Low to medium levels of microplastics (less than 5 mm in size) measured in the common blue mussel (Mytilus spp.), a filter feeder affected by ecosystem conditions, were measured to analyze the main kinds of pollution affecting the environment, and single-use plastic was the main offender.
Karen Burke da Silva, Study Senior Author and Professor, Flinders University
Microplastics are everywhere in the marine environment and tend to be more prevalent in mussel samples close to bigger towns and cities. The levels of microplastics found at such locations were four times greater at Semaphore Beach than at the highly remote Ceduna on the Eyre Peninsula.
By investigating microplastic load in the mussel, we call attention to the implications of microplastic pollution on South Australia’s unique marine ecosystems and on the local human food chain.
Janet Klein, Study First Author, Flinders University
Microplastic contamination noted at Semaphore Beach and then Hallett Cove is up to four times greater compared to tests run at Ceduna, and twice as high as Coffin Bay on the Eyre Peninsula.
In oceans across the world, trillions of microplastic particles can be found, with the greatest concentrations discovered recently in the shallow seafloor sediment off Naifaru in the Maldives (at 278 particles kg−1) and the lowest reported in the surface waters of the Antarctic Southern Ocean (3.1 × 10−2 particles per m3).
For the first time ever, the Flinders University study quantified the existence of microplastics found on the coastline of South Australia. These are in areas that are significant both for shipping, fishing and tourism, along with other industries and local communities.
Microplastic concentration present in the SA intertidal water was discovered to be low to moderate (mean = 8.21 particles l−1 ± 4.91) compared to global levels and microplastic abundance in mussels (mean = 3.58 ± 8.18 particles individual−1) - within the range also reported throughout the world.
Plastic types consist of polyamide (PA), polyethylene terephthalate (PET), polypropylene (PP), polyethylene (PE), acrylic resin and cellulose. This indicates both synthetic and semi-synthetic particles obtained from single-use fabrics, short-life cycle products, ropes and cordage obtained from the fishing industry.
“The areas examined include some biodiversity hotspots of global significance – including the breeding ground of the Great Cuttlefish in the Northern Spencer Gulf and marine ecosystems more diverse than the Great Barrier Reef (such as Coffin Bay), so cleanup and prevention measures are long overdue,” stated Professor Burke da Silva.
Burke da Silva added, “Apart from the harvesting of blue mussels, we also need to consider the impact of microplastic particles entering other parts of the human food chain with microplastic pollution expected to increase in the future.”
Journal Reference:
Klein, J. R., et al. (2022) Microplastics in intertidal water of South Australia and the mussel Mytilus spp.; the contrasting effect of population on concentration. Science of The Total Environment. doi.org/10.1016/j.scitotenv.2022.154875.