A toxic algal bloom has temporarily closed a popular bathing and recreation spot in Western Australia.
Swimmers, kayakers, anglers and their pets have been urged to avoid contact with water, due to the high risk of skin reactions and illness.
Part of the Canning River has been closed for any type of recreational use involving contact with water, given the presence of a blue-green bloom of the seaweed Dolichospermum circinale.
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The affected area extends for approximately 2.5 km upstream from Kent St Weir and up to Masons Landing in Cannington.
City of Canning health warning signs have been erected at major access points to affected areas along the river.
The Government of Western Australia’s Department of Biodiversity, Conservation and Attractions (DBCA), which regularly monitors microalgae in the Swan Canning River system each week, issued a warning this week.
“Flowering is characterized by a green discoloration of the water and can produce several types of toxins,” the DBCA said.
“Recreational activities such as swimming, wading, kayaking and fishing should be avoided.
“Pets are more sensitive and should not be allowed to enter the water in this area.”
The Department of Health warns that as a general rule, people should avoid water that has surface scum, is discolored, cloudy or smells bad.
In the same stretch of the Canning River, and 10 km further north on the Swan River, a different bloom of paralyzing shellfish toxin-producing algae Alexandrium was also reported by the DBCA.
“Microalgae activity was high from Rivervale to Maylands and Bassendean in the Swan, and between Shelly and Langford in the Canning this week,” he said.
Bathing for people and pets, water skiing and boating are only safe around a Alexandrium bloom if the water does not appear cloudy or smelly.
Fishermen are advised not to fish in the area, and also to avoid eating crabs, mussels or other bivalves caught there.
Eating infected crabs and mussels can potentially be fatal.
“At worst, paralytic shellfish toxin (PST) poisoning can be fatal to humans and there is no antidote, treatment being supportive care and artificial respiration.
“A meal of three to four whole crabs can cause symptoms.”
Blue swimmer crabs are a popular catch in the area, and the DBCA warns that if caught in these affected waters, anglers must follow strict guidelines for cleaning and preparing them.
“Clean all blue swimmer crabs caught in the Swan and Canning Rivers by removing the head, tripe, mustard and gills before freezing, cooking and eating them,” the DBCA said, adding that the crabs must first be transported home before being gutted and cleaned.
“Cooking whole crabs does not destroy the toxins and could potentially spread the toxin from the crab guts into the flesh or broth.
“Freezing whole crabs could cause paralytic shellfish toxins to spread into the flesh when thawed.”
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. Location bathing popular closed reason bloom algae toxic Canning River Swan River
. Popular swimming spot closed due toxic algae blooms Canning River Swan River