Action urgently needed as post-bushfire floods threaten river and coastal ecosystems

After widespread flooding from the much-needed rains in South Eastern Australia, marine conservationists have called for the urgent monitoring of sensitive rivers, estuaries and coasts, as sediment and ash-clogged waters from bushfire areas rush into these marine environments.

The scientific monitoring must be followed by management of any impacts for the sake of sensitive coastal environments and the fishery and tourism industries in regions already doing it tough following the unprecedented bushfire season.

Australian Marine Conservation Society (AMCS) fisheries spokesperson Adrian Meder said earlier rains in bushfire impacted areas had already resulted in mass fish kill incidents in rivers.

“The latest very heavy rains, while much needed and welcomed, will result in even more water choked with ash and sediment rushing down through our rivers and estuaries,” Meder said.

“These are sensitive habitats which are crucial nurseries for a range of commercially important fish, as well as endangered fish, seahorses, and seabirds.

“We need to understand the damage being done to aquatic environments, so we can manage this biodiversity crisis as it extends from land into sea following these heavy rains.

“We are calling on the state and federal governments to invest more in scientific monitoring and management so issues can be identified and tackled quickly and efficiently.

“South Eastern Australia is incredibly important for marine life and is home to endangered species found nowhere else. These species are already under significant pressure, including from our warming oceans so it is important state governments invest in managing these impacts and that our federal government supports them to do so.”

Meder said state governments have excellent scientific expertise in marine park staff, managers and University departments, that would be well placed to monitor and assess any impacts if adequate and timely resources were made available.

“Similarly there is now extensive expertise in habitat restoration in rivers, estuaries and coastal reefs, that could support quicker recovery of vital habitats with the assistance of coastal communities, divers, recreational and professional fishers,” he added.

The enormous bushfires which have raged across South Eastern Australia for the last six months have destroyed much of the natural filtration between land and ocean that forests provide.

The loss of this natural erosion barrier, particularly along coasts, could expose seagrass beds to choking sediment run off, and starve underwater plants in estuaries of sunlight, impacting the food chain.

The increasing loads of organic matter being washed into estuaries can lead to deoxygenation, toxic algal blooms and ultimately fish kill events.

“The impacts of the bushfires have been devastatingly obvious on land, but underwater the costs could be largely hidden until it is too late and we see fish kill events like those reported in Dubbo and Macleay,” said Meder.

He added that only urgent action on global warming with Australia transitioning to net zero emissions by 2050 would be effective in preventing another devastating bushfire season.

The AMCS is compiling a scientific report on the impacts to marine environments of the catastrophic bushfire season that is due to be published shortly.

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