Graph illustrating groundwater origins at the Great Barrier Reef. Attribution: Douglas Tait
Research reveals almost double the nitrogen is being introduced into the Reef via groundwater than through river systems.
Utilizing natural markers near the Queensland coast, researchers have identified unmeasured amounts of nitrogen and phosphorus that are significantly affecting the environmental stability of the Great Barrier Reef.
The study, released today in the journal Environmental Science and Technology, suggests that existing conservation and restoration initiatives aimed at the Reef may need reevaluation.
The pioneering research, entitled ‘Subterranean Groundwater Outflow Surpasses Riverine Contributions as a Nutrient Source to the Great Barrier Reef,’ is spearheaded by Dr. Douglas Tait of Southern Cross University.
Subterranean groundwater outflows are waters discharged into the ocean beneath the surface level, originating from various sources like underground water reservoirs and ocean floor.
Composite image showing unspoiled coral next to eutrophicated coral on the Great Barrier Reef. Attribution: Ashly McMahon
Research Outcomes and Consequences
The research consortium, which also involves CSIRO, AIMS, and the University of Gothenburg in Sweden, gathered information from ocean transects, river systems, and coastal wells in a region stretching from south of Rockhampton to north of Cairns. The use of radium isotopic markers enabled the researchers to monitor nutrient transportation from terrestrial and shelf sediment through unseen groundwater flows.
Professor Damien Maher of Southern Cross University indicated that the study revealed groundwater discharges were 10-15 times higher than those from rivers, a factor previously not considered.
“Groundwater discharges are responsible for about one-third of new nitrogen and two-thirds of new phosphorus entries, which shows that nearly double the amount of nitrogen is entering the Reef from groundwater in comparison to river sources,” stated Professor Maher.
He further noted that the majority of nutrient impact mitigation strategies have been focused on river outflows up to this point.
Projected Environmental Consequences and Guidelines
Lead researcher Dr. Douglas Tait emphasized that nutrients are crucial for sustaining the Reef’s extraordinary biodiversity.
“Nevertheless, nutrient surplus can result in negative effects such as noxious algal blooms, outbreaks of crown-of-thorns starfish, and an increase in fish illnesses, which have been escalating in the Reef over recent years,” he said.
Dr. Tait underscored the necessity for a tactical reorientation in management strategies that aim to shield the Great Barrier Reef from the negative impacts of excessive nutrients.
He mentioned that, unlike nutrients from river outflows, those from groundwater could be preserved underground for many years before entering coastal waters, implying that the approaches to protect the Reef need to be long-lasting.
“This research brings new insights into the intricate nutrient mechanisms at play within the Great Barrier Reef,” stated Dr. Tait.
“The capacity to effectively govern nutrient sources is critical for the enduring conservation of the Reef for future generations.”
Reference: “Subterranean Groundwater Outflow Surpasses Riverine Contributions as a Nutrient Source to the Great Barrier Reef” by Douglas R. Tait, Isaac R. Santos, Sèbastien Lamontagne, James Z. Sippo, Ashley McMahon, Luke C. Jeffrey, and Damien T. Maher, dated October 8, 2023, in Environmental Science & Technology.
Financial backing for the project was provided by the Australian Research Council, the Herman Slade Foundation, and the Great Barrier Reef Foundation.
Frequently Asked Questions (FAQs) about Groundwater Impact on Great Barrier Reef
What is the primary focus of the research on the Great Barrier Reef?
The primary focus of the research is to identify the sources of nitrogen and phosphorus affecting the environmental health of the Great Barrier Reef. The study reveals that groundwater is a significant, previously underestimated source of these nutrients.
Who led the research study?
The research study was led by Dr. Douglas Tait of Southern Cross University. The research team also included members from CSIRO, AIMS, and the University of Gothenburg in Sweden.
What methodology was employed for the study?
The research team collected data from offshore transects, rivers, and coastal bores. They utilized radium isotopic markers to track the amount of nutrient transported from the land and shelf sediment through unseen groundwater flows.
What are the key findings of the research?
The key findings indicate that groundwater discharges are 10-15 times greater than river inputs in delivering nutrients to the Great Barrier Reef. Groundwater accounts for about one-third of new nitrogen and two-thirds of new phosphorus entries into the Reef.
Why are these findings significant?
The findings are significant because they call for a reassessment of existing conservation and management strategies focused on the Great Barrier Reef. Prior efforts have mainly targeted river outflows, but the new research highlights the importance of also considering groundwater sources.
What are the environmental implications of excessive nutrients in the Reef?
Excessive nutrients can lead to harmful environmental consequences like noxious algal blooms, outbreaks of crown-of-thorns starfish, and an increase in fish diseases, all of which have been escalating in the Reef over recent years.
What recommendations does the study offer for conservation efforts?
The study recommends a strategic shift in management approaches to include groundwater as a significant source of nutrients. Conservation strategies need to be long-term, considering that nutrients in groundwater can be stored for decades before being discharged into coastal waters.
Who funded the research?
The research was financially supported by the Australian Research Council, the Herman Slade Foundation, and the Great Barrier Reef Foundation.
Where was the research published?
The research was published in the journal Environmental Science and Technology, dated October 8, 2023. The DOI for the publication is 10.1021/acs.est.3c03725.
More about Groundwater Impact on Great Barrier Reef
- Environmental Science and Technology Journal
- Southern Cross University Research
- Australian Research Council
- Great Barrier Reef Foundation
- CSIRO (Commonwealth Scientific and Industrial Research Organisation)
- AIMS (Australian Institute of Marine Science)
- University of Gothenburg
- Herman Slade Foundation