Magnetic Island is a beach lover’s tropical paradise located only 15 minutes away by ferry from Townsville. It is now under threat from commercial dredging activities, to accommodate the recent expansion of the Port of Townsville. In reality, the expansion took place from 2018 through 2024. Today, vessels of 300 meters in length, with depths of up to 15 meters, have no difficulty berthing at the port. The purpose of the development is to increase trade and shipping capacity. At the same time, environmentalists and marine biologists are alarmed by the damage being done to the underwater ecosystem as a byproduct.
Gethin Morgan from Magnetic Island Nature Care has spent the last 30 years developing a deeper understanding of the underwater world. He writes eloquently about his worry for its continued decline. He critiques the current practice as unsustainable and argues for a more eco-friendly design. “It’s completely unsustainable. It’s not an example we should use to plan for the future,” he states.
Dredging and Its Environmental Impact
Annually, the Port of Townsville handles some 11 million tons of cargo. For one month, they remove 400,000 – 450,000 cubic meters of sediment from the bottom of the city’s international shipping route. This practice aims to maintain navigable waterways but has raised alarms among environmentalists regarding its implications for local marine life.
The port is now allowed to dump this underwater dredged material at a depth of 10 to 16 meters. They gave the disposal site the environmentally friendly-sounding name of Dredge Material Placement Area. They excluded it from the Great Barrier Reef Marine Park. This controversial decision initiated a heated public discourse about the possible long-term impacts on the fragile ecosystem surrounding it.
Dr. Eric Wolanski, a marine scientist with long ties to the region, released extensive research over the years indicating the precarious health of the entire Cleveland Bay ecosystem. His research shows that dredging has made the bay’s natural murkiness worse by introducing more sediment into the water. “The water has become very turbid and it has decreased from 8m visibility in the 1960s to 1m nowadays,” he notes.
Dr. Wolanski’s modeling has shown that strong currents are re-circulating the dredged mud dumped around Magnetic Island. This new pro-development movement is an environmental double whammy.
The State of Magnetic Island Reefs
Marine biologist Andy Lewis has been keeping a close watch on the reefs surrounding Magnetic Island for more than two decades. Though worried about sedimentation, he thinks these reefs are still in pretty good health. He acknowledges that while dredging increases sediment load in the water, “the reefs around here are adapted to living in a high sediment environment.”
Lewis points out that some of the most biodiverse coral reefs — those with the highest amount of coral cover — are found in regions with extremely high flow of sediment. This resilience highlights the unique and often counterintuitive ways that the ecosystem responds to human impacts. He states, “I think everything that we can do now to limit the amount of pressure on our reef system is valuable.”
Challenges remain. Natural disasters like Cyclone Tessi have made protecting existing coral even more crucial and more difficult. Dr. Wolanski mentions that while cyclones have damaged intertidal corals, “the subtidal corals below the high tide mark are still in really good condition.”
Future Considerations for Dredged Material Management
Moving forward, the Port of Townsville aims to start formulating beneficial use strategies for handling dredged material in the next 10 years. Community input will be extremely important in deciding how this spoil is placed. Morgan supports dumping dredged material in deeper waters but says rigorous modelling needs to happen first before any decision is made.
Our ask has been for this material to be placed in deeper water. We need to do the right modeling before that can be realized. He asserts.
As national debates rage over the links between environmental sustainability and economic development, Magnetic Island is at a historic crossroads. It is essential that stakeholders balance trade interests with ecological preservation to ensure the ongoing health of this vibrant marine ecosystem.
