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UPDATE: 24/02/2023 - The information on this website is currently under review.

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Warmer weather brings smelly weeds to Swan River foreshore

Warmer weather brings smelly weeds to Swan River foreshore

As summer approaches, the Department of Biodiversity, Conservation and Attractions is reminding people that seagrass and macroalgae often accumulates on shorelines at this time of year and may emit odours as part of a natural breakdown process.

DBCA Rivers and Estuaries Director Mark Cugley said submerged vegetation played an important role within the river system as habitat for fish and sea horses and as a food source for black swans.

“Macroalgae and seagrass in the Swan River can grow rapidly at this time of year due to increases in temperature, available light and nutrients and then, as it dies off, prevailing winds and tides can cause it to accumulate as wrack on some foreshores of the Swan Canning Riverpark,” Mr Cugley said.

“While the accumulated wrack odour can be unpleasant, water movement due to winds and tide will often disperse this material naturally and the removal of wrack is only carried out as a last resort due to the ecological benefits of leaving it in place.

“Where it is practical to remove wrack, it needs to be dry before being taken offsite for disposal and may be stockpiled to dry for several days if required.

“This decision is made in consultation with local governments, which have a shared responsibility for the foreshore.”

Mr Cugley said managing nutrients was an essential step in trying to reduce macroalgae in the Swan Canning Riverpark.

“The Swan Canning Water Quality Improvement Plan guides management actions aimed at reducing land-based sources of nutrients to improve estuarine water quality,” he said.

“As part of this effort, DBCA is working with land managers and the community in priority catchments to reduce nutrient use and input into the river system.”

DBCA and Edith Cowan University have also teamed up to better understand the biodiversity and ecological values of seagrass and seaweed accumulations in the Swan Canning Riverpark.

For more information about seagrass and seaweed accumulation, contact the DBCA Parks and Wildlife Service on 9278 0900.