Scientists have embarked on an ambitious expedition to map ancient terrestrial landscapes now submerged beneath the waters of the Great Barrier Reef. The research aims to uncover the environmental and cultural history of a region that existed as dry land approximately 65,000 years ago, when sea levels were significantly lower than they are today.
Uncovering Pre-Submergence Landscapes
Led by Professor Helen Bostock from the University of Queensland, a recent 24-day voyage aboard the CSIRO research vessel RV Investigator focused on an area off the Central Queensland coast. This region, now part of the Southern Great Barrier Reef, was once a vast landmass potentially supporting grasslands, dense rainforests, or mangrove swamps. The expedition’s goal was to reconstruct what this ancient ‘sea country’ looked like before it was inundated by rising sea levels.
Professor Bostock described the findings as revealing “submerged rivers, lakes, estuaries and beaches in stunning detail.” The team collected sediment samples from the seabed at depths ranging from 50 to 200 meters, specifically between the Swain Reefs and the Capricorn Bunker Group, off the coastlines near Yeppoon and Gladstone. These samples act as a historical archive, with the layers of sediment preserving records of past environments.
Sediment Cores: A Journey Through Time
The analysis of sediment cores provides a chronological record, allowing researchers to delve back through time. “If we start at the top of a sediment core that we’ve collected down through those sequences, we can basically go back through time from the top down towards the bottom of our cores,” explained Professor Bostock. Each layer contains valuable information, including changes in grain size, chemical composition, and microfossils such as pollen, which offer clues about the past ecosystems.
The ultimate aim is to generate detailed maps of these submerged landscapes, thereby enhancing the understanding of both the environmental and cultural history of the area. This research is crucial for understanding how the reef system evolved and how past environmental changes might inform future reef health.
Indigenous Collaboration and Cultural Knowledge
A significant aspect of this expedition was the collaboration with Indigenous Land and Sea Rangers from the Darumbal and Woppaburra traditional owner groups. Their involvement was key to integrating scientific findings with invaluable cultural knowledge and oral histories passed down through generations.
Professor Bostock highlighted that conversations with elders, including Auntie Sally Vea Vea, about cultural stories of people traversing to Swains Reefs when it was dry land, served as a primary inspiration for the voyage. This underscores the deep connection Indigenous communities have with the land and sea country, extending back thousands of years.
Tshinta Barney, supervisor for the Woppaburra land and sea rangers, expressed her excitement about the potential revelations from the sediment samples. “When you put in the Western science and see the degree that they go to, you can really see where our stories and our family ties all come into one,” she stated. Barney emphasized how Western science can validate and complement traditional knowledge, providing a more comprehensive understanding of the past. She also expressed a desire to pass this knowledge on to younger generations, encouraging their participation in such scientific endeavors.
Darumbal land and sea ranger Nataliah Backo shared her pride in being able to work on the ancestral sea country. “It’s just amazing that we got to be on the sea country that our ancestors used to live, walk and hunt on,” she remarked, reflecting on the profound connection to her heritage.
Broader Oceanographic Research
Beyond mapping ancient landscapes, the expedition also focused on collecting vital oceanographic data. This includes information on sediment movements, nutrient levels, and water temperatures. Understanding these factors is critical for assessing the current health of the Great Barrier Reef and predicting how it might be affected by ongoing environmental changes.
The research team also identified a “drowned” coral reef in the deep ocean, a testament to the dramatic sea-level changes the region has experienced. This discovery further illustrates the dynamic geological history of the area.
Future Insights and Analysis
While the oceanographic data is expected to be analyzed and available within the next year, the detailed analysis of the sediment samples will take considerably longer. The insights gained from this comprehensive study are anticipated to provide a richer understanding of the Great Barrier Reef’s history, its ecological evolution, and its deep cultural significance.
The project represents a significant step forward in interdisciplinary research, merging cutting-edge scientific techniques with ancient Indigenous knowledge to unlock the secrets held within the submerged landscapes of Queensland’s coast.
