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Dead mangroves at Boambee Creek: scientists and Indigenous rangers worried

Boambee sieving mud with Gumbaynggirr rangers


23 November 2023

A bird’s-eye view of a forest of dead mangroves shocked Southern Cross University’s Professor Kirsten Benkendorff as her plane approached Coffs Harbour airport earlier this year.

The mangroves are an essential part of the Boambee Creek Estuary which weaves along the southern and south-west perimeter of the airport.

“A bit of investigating on NearMaps revealed that the mangrove forest was hit hard by a hail storm in October 2021, but two years on it had still not recovered,” said Professor Benkendorff.

“This is a worry because mangroves are really important ecosystems that provide habitat to fish, sequester carbon and help protect our shoreline.”

“We found a range of toxic chemicals in the rotting mangrove roots. This indicates that the site is not very safe for people or aquatic life.”

Kirsten Benkendorff

Professor Benkendorff (main image, wearing blue shirt) joined up with the Gumbaynggirr Rangers to investigate what was going on. The Gumbaynggirr Rangers and their cultural work is supported by an Indigenous Protected Area Sea Country program, and is important for helping local indigenous people heal country.

Their inspection of the site revealed most of the mangroves were rotting away and the mud underneath was black and stinking.

“There was none of the usual life like crabs and snails living in amongst the mangroves. There was a strong smell of sulphur and the occasional smell of something more like petrol,” said Professor Benkendorff.

The Ngiyambandigay Wajaarr Aboriginal Corporation received a grant from the Coffs Harbour City Council Environmental Levy program to support further research. The Corporation said: “When Country is sick, we are also sick”.

Mangrove dieoff at Boambee Creek from the air
Dead mangrove forest at Boambee Creek as seen from the air (credit Kirsten Benkendorff).

The findings of analyses from the mangrove roots and mud, by the University’s Analytical Research Laboratory, concerned Professor Benkendorff and the Gumbaynggirr Rangers.

“We found a range of toxic chemicals in the rotting mangrove roots, including carbon disulphide and petrochemicals like naphthalene, furan, xylene and cresol. Many of these chemicals are neurotoxic when inhaled and irritants to the eyes, skin and lungs,” said Professor Benkendorff.

“This indicates that the site is not very safe for people or aquatic life.”

The Boambee Creek Estuary is a popular place for kayaking, walking and fishing.

The Gumbaynggirr Rangers and the Southern Cross University team are now collaborating to grow mangroves to help stabilise and restore the site.

Rob Briggs, Coordinator of the Gumbaynggirr Rangers, said they were concerned about how industry and urbanisation have encroached on significant areas of cultural value to the Gumbaynggirr people.

“We hope that through our research, we can find ways to restore harmony and heal Country,” Mr Briggs said.

“The key is to have First Nations-led solutions, and we are proud to be doing this vital work on Gumbaynggirr Country.”

Satellite images of the mangrove dieback site: after the October 2021 hailstorm (left); in August 2023 (right), the mangrove forest (circled) still hasn't recovered (credit NearMap).

Media contact

Sharlene King, Media Office at Southern Cross University +61 429 661 349 or