In Short
The Great Barrier Reef and Torres Strait have experienced six bleaching events since 2016, including back-to-back occurrences in 2016-17 and 2024-25. Experts are urging a greater focus on water quality, as increasing flooding creates “flood plumes” that harm reef ecosystems.
The Current State of the Great Barrier Reef
It is no secret that the world’s largest coral reef is under significant pressure. Coral bleaching, crown-of-thorns starfish outbreaks, cyclonic weather events, and rising sea temperatures frequently make headlines regarding the health of Australia’s Great Barrier Reef.
This February, freshwater flood plumes reached reefs up to 100 kilometres off the coasts of North and Far North Queensland, underlining a pressing concern: water quality.
On Orpheus Island, approximately 3,000 giant clams perished due to floodwater from the Herbert River catchment. Marine biologist Dr. Richard Braley, who spearheaded a significant restoration project in the 1980s, expressed his dismay: “These organisms are stenohaline, meaning they can’t handle a broad range of salinity changes. It was a sad event; they survived there for 40 years without a problem.”
Floodwater brought sediment that lowered salinity by about 70 percent. Jenni Calcraft, manager of James Cook University’s Orpheus Island Research Station, reported observing “clam bodies” floating away: “The tissue bits were just washing up on the beach,” she said. “Essentially, they had this two-to-three metre lens of freshwater sitting on top of them for so long that their tissue disintegrated and they didn’t survive.”
Efforts to Improve Water Quality
In response to these challenges, TropWATER, an organization working with wetlands and aquatic ecosystems in North and Far North Queensland, has made significant strides in recent years. Professor Damien Burrows, the organization’s director, highlighted recent successes in helping farmers and landholders adopt environmentally friendly practices.
TropWATER collaborates with cane farmers to monitor nitrogen levels in their fields and prevent runoff into local catchments. They also focus on wetland restoration and replanting riparian zones to mitigate runoff into waterways. Professor Burrows noted, “Nutrients and sediments can create flood plumes during the wet season, blocking light and affecting the growth of seagrass and coral.” He emphasized that while global warming is beyond local control, improving water quality is achievable: “It’s a very solvable problem from that point of view.”
Addressing Multiple Threats
Max Hirschfield, a campaigner with the Australian Marine Conservation Society, stresses the importance of addressing all threats to the Great Barrier Reef simultaneously. He criticized the Australian government’s response to managing water quality targets, stating, “There’s not sufficient publicly available data to evaluate the efficiency of reef water quality programs.” He warned that the increasing intensity and frequency of cyclones, flooding, and marine heatwaves due to climate change pose serious risks to the reef.
The Australian Institute of Marine Science (AIMS) reported that some parts of the Great Barrier Reef experienced the largest annual decline in coral cover in nearly 40 years. Since 2016, six mass coral bleaching events have affected the region, with back-to-back occurrences in 2016, 2017, 2024, and 2025, leaving corals with limited recovery time.
Federal Environment Minister Murray Watt announced that the Queensland and Commonwealth governments have invested over $5 billion from 2015 to 2030 to manage threats and build resilience in the Great Barrier Reef, including significant funding for water quality improvements.
Finding Hope Amid Challenges
Despite the challenges posed by recent flooding and bleaching events, Professor Burrows remains optimistic about the future of the reef. He noted that most of the nutrients running off to the reef originate from a small portion of the catchments, allowing targeted remedial work to make a difference. “I feel science is making a difference,” he said. “We can’t completely restore the reef to its original state due to ongoing climate change, but we can slow down its decline and maintain a much higher level of condition.”
