Surveys at ten coastal sites in the Wet Tropics are taking a closer look at what’s washing up along the Reef.

So far, the news is encouraging. While microplastics have been recorded along these shorelines, contamination levels remain low likely due to lower population density and less urban pressure than more heavily populated areas.

What are microplastics?

Microplastics are tiny plastic particles less than five millimetres in size. Some are intentionally this small — such as microbeads that were once used in cosmetics or the microfibres from synthetic clothing. However, most microplastics recorded in the Wet Tropics are hard fragments, indicating they originate from the larger plastic that have broken up.

Why are they a problem?

Unlike organic materials, plastic does not biodegrade. Instead, it breaks up into smaller and smaller pieces that can exist in the environment for decades or even centuries.

Many microplastics eventually settle in sediments — which are important feeding grounds for fish, crustaceans and other aquatic species. They can also act like tiny chemical sponges, absorbing pollutants including heavy metals, pesticides and hydrocarbons. This cocktail of contaminants may then be ingested by marine life. The full ecological impacts are still not fully understood but research suggests microplastics can cause stress, physical injury and feeding problems for aquatic organisms.

How do microplastics reach the Reef?

Microplastics enter waterways through litter, landfill leaching, stormwater runoff and sometimes wastewater treatment systems. Major sources include fibres shed from synthetic clothing during washing, microscopic particles from vehicle tyres wearing down on roads, fragments from paints and coatings, and the breakdown of ageing plastic materials and infrastructure.

Microplastics can also be transported over longer distances by ocean currents so some particles found on the Reef may have originated from outside the region.

What is being done to reduce plastic pollution?

A range of initiatives are underway. In Queensland, the state government has introduced bans on several single-use plastic items. Locally there are programs such as Plastic Free Places which is helping hospitality businesses in Cairns and Port Douglas to transition away from disposable plastics. Globally, the United Nations is working towards a plastics treaty, aimed at reducing plastic pollution across its entire lifecycle.

What can we do about it in the Wet Tropics?

• Choose products with less single-use packaging.
  
• Support businesses that use compostable or reusable materials.
• Choose natural fibres over synthetics.
• Join community clean-up events.

The Australian Microplastic Assessment Project (AUSMAP) has partnered with Tangaroa Blue Foundation through the ReefClean Project since 2019. It is funded by the Australian Government’s Reef Trust. Visit tangaroablue.org and https://www.ausmap.org/hotspot-map for more information.