Research team leads the way in river flood research

A SOUTHERN Cross University research team has spent three years working on a project to reveal the long-term impacts of flooding on local estuaries across multiple rivers.

One of the key areas has been the Richmond River at Ballina which is still struggling to recover from the 2022 floods.

The research team found heavy metal deposits and sedimentation at the upper catchment where a lack of invertebrates leads to less food for the fish population.

SCU professor Kirsten Benkendorff has been at the helm of the project which has monitored six river systems.

“After collecting three years of data we can see of the rivers have ongoing impacts up stream,” she said.

“We’re trying to feed back the importance of water quality, stop sediment runoff into our rivers and protect our estuarine habitats as much as possible.”

Worms, cockles and crabs are at the bottom of the river food chain but are important to fish stocks.

They were affected by heavy sedimentation following the floods.

Heavy metal deposits and sedimentation are still present in the upper catchment, while the lower catchment near the sea has recovered.

“Worms are everywhere (at Ballina), the little yabbies and other things we see indicate the biodiversity level,” Ms Benkendorff said.

“We don’t often see what we’re looking for until we get the samples under the microscope.

“We’re lucky now, straight after the floods we were swimming through mud to get our samples back to the boat.”

The research team has been supported by OZ Fish Unlimited, which aims to protect and restore fish habitat.

The group’s North Coast project officer Zoe White is part of the program and said ongoing efforts were being made to help support estuaries.

One of the plans is an oyster reef restoration project in the river which would improve water quality and support invertebrates.

“The fish kills after the 2022 floods were significant with thousands upon thousands of them dying,” she said.

“It’s not uncommon to see smaller incidents of fish kills in the Richmond River as well.

“There is a big need to restore our habitat through ongoing efforts to stop that from happening.”