In 2019-20, the Black Summer bushfires burned 24 million hectares of land across Australia. Of that, 870,000 hectares of forests and coastal ecosystems were affected in the East Gippsland bushfire region.
Victoria's Gippsland Lakes Ramsar site – Australia’s largest estuarine lagoon system – was not directly burnt, but the fires burnt across the catchment, impacting water quality.
Gippsland Lakes was listed as a Wetland of International Importance in 1982 under the Convention on Wetlands, or Ramsar Convention.
This means it must be managed to ensure its ecological values are maintained.
But the threats caused by climate change, such as increased bushfire risk, are creating challenges for wetland managers.
The need to protect and maintain the site goes further than the Ramsar Convention. The waterways hold important cultural, social, environmental and economic values.
The site is valued by the Gunaikurnai People, Traditional Custodians of the site for thousands of years.
It's also a popular tourist and recreational fishing destination.
In 2021, the Australian Government commissioned CSIRO to research the site’s vulnerability to bushfire and climate change, as part of a $200 million Bushfire Wildlife and Habitat Recovery package.
The multidisciplinary team at CSIRO, led by Principal Research Scientist Dr Dewi Kirono, collaborated with a number of different groups, including the East Gippsland and West Gippsland Catchment Management Authorities, the Gunaikurnai Land and Waters Aboriginal Corporation, the Victorian Government and local community groups.
The Vulnerability of the Gippsland Lakes Ramsar Site and its catchment to bushfire and climate change report was released in May 2022.
The report outlines the challenges the Gippsland Lakes will face as temperatures rise, sea-levels increase, rainfall varies and the region has more bushfires due to climate change.
The Black Summer fires
The 2019-20 bushfires destroyed vegetation along the rivers that flow into the Gippsland Lakes, which took a toll on the water quality at the lakes.
CSIRO Principal Research Scientist Dr Dewi Kirono says rainfall following the fires caused huge concentrations of sediment, ash and other pollutants to enter the lakes through the Mitchell, Nicholson and Tambo rivers.
“The water flow contained up to ten times higher than normal concentrations of total suspended solid, total nitrogen and total phosphorus in the first year after the bushfire runoff event,” she says.
East Gippsland Catchment Management Authority program manager Sean Phillipson says this had an impact on the area’s ecosystem.
“Aquatic plants and animals are influenced by the water quality of the systems they live in, and changes were experienced to the distribution of some species immediately following initial rains after the fires,” he says.
"During fires, increased water temperatures, combined with ash and nutrients, can reduce dissolved oxygen in the water, killing fish and other aquatic species."
While Gippsland has experienced fires nearly every year since the 1880s, the number of fires in the region has increased in recent decades.
The Gippsland Lakes in the year 2050
Droughts, bushfires and floods strongly influence the ecology and hydrology of the Gippsland Lakes Ramsar site, and the frequency and magnitude of these threats are on the rise.
Dr Kirono says CSIRO undertook a climate change vulnerability analysis of the Gippsland Lakes in collaboration with local community groups and other stakeholders.
“Environmental challenges are complex and can’t be addressed by individual disciplines operating in silos," she says.
“Collaboration with different groups enabled us to do a more cohesive study and to obtain a more comprehensive understanding brought by a diverse group of people."
Participants took part in a series of workshops to identify environmental sensitivities, assess the likely impacts of changes, and explore management options.
For the vulnerability analysis, researchers developed a scenario on how the Gippsland Lakes could look in 2050, representing the greatest plausible change.
In the scenario, the projected temperature in the Gippsland region would increase by 1.6 degrees Celsius and extreme temperatures would rise by up to 2.9 degrees.
This warming, combined with increased nutrients in the water, could lead to toxic algal blooms, suppressing aquatic vegetation and other species.
The analysis projected a 25cm sea-level rise, which would inundate existing shoreline habitats, including saltmarshes, near shore habitats and beach-nesting areas.
Moreover, fire seasons would begin earlier and last longer, and the water quality of the Gippsland Lakes would be impacted by sediment and debris from burned catchments.
Dr Kirono says the Gippsland Lakes are also vulnerable to more seawater and less freshwater flowing into the lakes, impacting freshwater-dependent plants, fish and waterbirds.
“And so, the site’s values associated with freshwater components will possibly be lost or at least significantly diminished,” she says.
Protecting the site against climate change
Dr Kirono says the most important ‘next steps’ for protecting the site are to manage the threat of bushfires and the decreasing amount of freshwater flowing into the catchment.
“This would include continuing to conduct consistent water quality monitoring, initiating an Adaptation Planning Process and undertaking activities to help communities understand change that has been, and will be happening,” she says.
The Gippsland Lakes currently meet six out of the nine Ramsar nomination criteria.
Dr Kirono says the site will continue to meet the criteria as long as the impacts of climate change are taken into consideration when managing the site.
“However, the specific ways it meets some of those criteria may change, for example, which threatened species are present, or which habitat types are represented,” she says.
Mr Phillipson says maintaining the health of the Gippsland Lakes is a long-term commitment by government in partnership with Traditional Custodians, the community and other organisations and groups.
“The involvement of this wide range of people, guided by clear priorities, helps to maximise the benefits of the work done to protect the lakes," he says.
“Change across the system is likely to increase into the future due to an increasing population and a changing climate altering the system further.
“But the Gippsland Lakes will continue to adapt to the changing conditions, and with efforts by all of us, key values can be maintained, and new values are likely to emerge."
The implementation of the Gippsland Lakes Ramsar Site Management Plan was coordinated by the East Gippsland Catchment Management Authority providing direction for 2015 to 2022.
Read the final report, Vulnerability of the Gippsland Lakes Ramsar Site and its catchment to bushfire and climate change.