Rangers and scientists map vulnerable reefs in the remote Groote Archipelago

For millennia, the Anindilyakwa people have sustained a profound connection with the waters encircling Groote Eylandt, a secluded island within the Gulf of Carpentaria. This region harbors some of Australia's most culturally and ecologically significant coral reefs, yet the waters surrounding Groote Eylandt have remained largely undocumented by contemporary science.

A recent study has now unveiled the most comprehensive portrait yet of these under-researched coral reefs, laying the groundwork for ongoing monitoring and preservation efforts.

Annabelle Doheny, a former Anindilyakwa Land and Sea Rangers Indigenous Protected Area coordinator, deemed the coral reefs of the Groote Archipelago among the most mesmerizing she has witnessed. Having dived on the Great Barrier Reef and Ningaloo Reef, Doheny confidently asserts that the marine life encountered around the Groote Archipelago surpasses those other renowned sites.

The new research, co-authored by Anindilyakwa Land and Sea Rangers and scientists from the University of Technology Sydney, has been published in the journal PLOS One. It meticulously documents the seafloor life and geology of five reefs encircling Groote Eylandt using underwater remotely operated vehicles (ROVs) deployed in challenging waters due to saltwater crocodiles and jellyfish.

Ph.D. researcher and lead author Dane Wattle emphasized that coral reefs worldwide confront increasing and intense stressors capable of pushing them into degraded states, with enduring ramifications. To formulate an enduring conservation strategy capable of safeguarding reefs amidst environmental transformation, it is imperative to comprehend the existing state of the reefs.

Unfortunately, the Gulf of Carpentaria lacked comprehensive data on its coral reefs, with only seven studies published to date, none of which focused on Groote Eylandt or specifically on coral. The surveys conducted largely using ROVs yielded coral cover percentages ranging from 5% to 47%, predominantly featuring resilient massive corals rather than the branching varieties prevalent on other reefs.

The technology employed enabled researchers to survey the reefs in waters that are notoriously difficult and often hazardous to access.

The fieldwork coincided with a stress event in early 2024, and satellite data revealed elevated sea temperatures preceding the event, albeit not at the levels typically associated with severe coral bleaching. However, it was the on-the-ground surveys conducted by the ranger team that initially identified mass coral bleaching at several sites within the Gulf of Carpentaria.

The study's senior researcher, associate professor Emma Camp, challenged the notion that marginal reef systems possess inherent resistance to heat stress. Remote reefs like these have, regrettably, often been relegated to the periphery of conservation efforts, despite their crucial importance to the communities that depend on them.

The research is the outcome of a close collaboration between UTS scientists, Anindilyakwa Land and Sea Rangers, and Traditional Owners. Rangers guided the team to critical reef sites utilizing traditional knowledge, while scientists equipped the rangers with the skills to pilot ROVs and drones. Doheny, who obtained an honors degree under Camp's supervision at UTS, concurred.

Traditional knowledge holders can provide invaluable context for an area, narrating stories of environmental shifts they have observed over time. Scientists, in turn, can document these changes using modern technology to devise management approaches that protect these ecologically and culturally vital ecosystems.

The reefs face numerous challenges. Climate change and sea level rise threaten the low-lying areas and culturally significant marine sites of Groote Eylandt. Closer to shore, the region's extensive manganese mine anticipates significant water inundation issues as it approaches a projected closure in 2032. The proposed ocean outfall to pump substantial volumes of water into the sea has raised concerns regarding its potential impact on nearby coral, seagrass, and marine microorganisms.

While Traditional Owners possess strong rights over land under the Aboriginal Land Rights Act, protections for marine environments are comparatively limited, despite Sea Country constituting approximately 70% of the Anindilyakwa Indigenous Protected Area. For a community that relies on the reefs for subsistence fishing and cultural well-being, this creates a significant gap in protection precisely where ecological and cultural value is most pronounced.

With the baseline data now established, the research team is pursuing additional funding to advance the project, focusing on refining reef taxonomy, including the potential discovery of unique or endemic species, and investigating the corals' resilience to rising temperatures and diminished oxygen levels. Beyond its scientific contributions, the project has significantly altered the Anindilyakwa Land and Sea Rangers' approach to Sea Country management.

Doheny noted that the project has propelled coral reef monitoring onto the radar of the Anindilyakwa Land and Sea Rangers, with building it into the yearly work plan becoming a priority. The rangers now enthusiastically engage in this activity.