Micro-algae bloom likely cause of fish deaths and foam at Waitpinga Beach
By Eva Blandis
By Caroline Horn
Topic:Environment
6m ago6 minutes agoTue 18 Mar 2025 at 3:30am
dead octopus about the length of six mobile phones on a beach
Dozens of dead octopus were seen on Basham Beach on Tuesday. (ABC News: Caroline Horn)
In short:
A micro-algae bloom is the likely cause of dead marine life reported from Waitpinga to Basham Beach in the Fleurieu Peninsula, the EPA says.
The Department of Primary Industries and Regions (PIRSA) is investigating the fish deaths.
What's next?
Initial results from water testing would be available in about a week.
Dead octopuses have been found along South Australian beaches as environment authorities say a micro-algae bloom could be to blame for fish deaths on the weekend.
Dozens of dead octopuses and other marine life washed up at Encounter Bay and Basham Beach in the Fleurieu Peninsula.
Several people reportedly experienced sore eyes, coughing and blurry vision after visiting Waitpinga and Parsons beaches on the weekend before the environment department closed both beaches on Monday.
Dead octopus lying in seaweed next to car keys washed on beach
Dead octopus washed up at Encounter Bay seen on Tuesday. (ABC News: Caroline Horn)
The Department of Primary Industries and Regions (PIRSA) is investigating the fish deaths and a discoloured foam seen at Waitpinga.
PIRSA said it has received reports of fish mortalities from Parsons Beach to as far as Basham Beach.
"It is considered that they are all part of the one event," a PIRSA spokesperson said.
Principle marine scientist at the Environment Protection Authority South Australia (EPA) Sam Gaylard said micro-algae blooms are the likely cause of the issues — but it is yet to be determined which species it is.
Close up of a man in a garden
EPA SA marine scientist Sam Gaylard says a micro-algae bloom could be killing fish. (ABC News: Che Chorley)
"We're seeing a micro-algae blooms, so a phytoplankton bloom in the water, which has been driven by the long hot period of fine weather, low winds and low tides so that's created the conditions which are right for a bloom of algae," he said.
"At this time of year we do occasionally get isolated blooms but something of this scale is definitely unusual."
Mr Gaylard said the micro-algae has been impacting fish or people who jump in the water in the area.
A pink sea slug-like creature next to sea grass on the beach
Dead marine life washed up at Encounter Bay. (ABC News: Caroline Horn)
"What we're seeing on the beach [are] the fish that have succumbed to that and largely they are reef-attached fish so they are likely to be living around the headlands around Waitpinga or Parsons," he said.
"But also could potentially be from further afield where the algal bloom may have impacted and the fish has washed in.
"The swell has increased since Sunday and so that action is breaking up the algae, causing the foam."
A large build up on cloud like foam on a beach.
Foam build up on Waitpinga Beach on Monday. (ABC News: Caroline Horn)
Mr Gaylard said there is still the potential for the issue to spread along the Fleurieu Peninsula, but it is hoped a change in weather will help break up the micro-algae blooms.
"There is the potential for that to happen … we're hoping that the change to the southerly wind, an increase in the surf we had on Sunday with a passage of a cold front should be working to break up the bloom and hopefully disperse it," he said.
"But it is always a possibility with more fine weather."
Testing results in a week
PIRSA and the EPA have sent scientists to the affected areas to collect water samples and environmental data to find out the exact cause.
"We've sent some marine scientists down to Waitpinga and Parsons to take water samples and to take observations of some of the fish and sea life that has washed in," he said.
"We're getting those samples analysed and that will be able to identify the species of algae that it is and we'll be able to have some certainty about what exactly has gone on."
Abalone with no top shell on a beach
More marine life washed up at Encounter Bay on Tuesday. (ABC News: Caroline Horn)
He also said their investigations will determine the type of micro-algae, saying it can either impact sea life as a toxin or a physical structure.
"In other circumstances, the sheer load of phytoplankton in the water can strip the oxygen out of the water and make it difficult for the fish to breathe," he said.
"We think that it is probably an irritant, so a phytoplankton with some spiky structure to it but we really want to identify what the species is to confirm that."
dead octopus tangled up in seagrass next to car keys for scale on beach
Octopus spotted on Basham Beach on Tuesday. (ABC News: Caroline Horn)
PIRSA said initial results from water testing should be received within about a week.
Mr Gaylard said it is too early to determine why the foam is impacting humans, but urged people to avoid affected beaches.
"We would suggest that if there is foam and dead sea life at other beaches perhaps get in contact with the FISHWATCH hotline, let us know because the people out there are our eyes and ears," he said.
SA Health said there have been no reported hospitalisations linked to the incident.
Posted6m ago6 minutes agoTue 18 Mar 2025 at 3:30am
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