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Thu, 13 Jul 2023

No refuge from plastic

Plastic waste
Bundle of nylon rope that was part of an anchor line entangled on coral at 100-m depth in Palau. Image: Luiz Rocha

A major global study published in Nature today reveals coral reefs at all depths are impacted by plastics and other human-sourced debris.

Dr Gemma Galbraith, a Research Associate working on the ecology of deep coral reefs, and Mr Ben Cresswell, a PhD student, both at James Cook University’s College of Science and Engineering and ARC Centre of Excellence for Coral Reef Studies, took part in the international study.

The team, led by Dr Hudson Pinheiro and Dr Chancey MacDonald from the California Academy of Sciences, surveyed 84 reefs around the globe, looking for macroplastics (plastic debris larger than 5 cm) and other manufactured debris.

“The team studied both shallow reefs less than 30 m deep and deep reefs between 30 – 150 metres, the latter of which are less well-documented,” said Dr Pinheiro.

Dr Galbraith and Mr Cresswell conducted Remotely Operated Vehicle surveys in Australia’s Coral Sea Marine Park to provide observations of deep-reef debris to this study.

“This was a great opportunity to contribute data from Australian deep reefs to a global study,” said Dr Galbraith.

The team found human-sourced debris at 77 of the 84 sites, with macroplastics accounting for 88% of the items found.

“Levels of macroplastics were higher in deeper reefs. In most surveyed areas, fishing activity was identified as the main source of plastic, as evidenced by lines and discarded traps,” said Dr MacDonald.

Mr Cresswell said macroplastics were present in nearly all surveyed locations, including very remote and relatively pristine coral reefs.

“The lowest densities were observed in the Marshall Islands, Australia’s Coral Sea Marine Park, and in Micronesia. Much higher densities were found on the reefs of the Philippines, Comoros, and offshore Brazil. The highest density, in the Comoros, would be spatially equivalent to approximately 520 pieces of debris in one football field,” said Dr Pinheiro.

The scientists said as the world moves towards a global treaty to tackle plastic pollution, understanding its distribution and drivers provides key information to help to design the strategies needed to address the threat.


Dr Gemma Galbraith
E: gemma.galbraith@jcu.edu.au

Mr Ben Cresswell
E: benjamin.cresswell@jcu.edu.au