Spectacular volumes of sea foam have been generated along the south coast of South Australia as floodwaters from the mouth of the Murray River, waves and wind combine.
CSIRO algal molecular biologist Anusuya Willis says the phenomenon is caused by organic material in the floodwater as it mixes with seawater.
“You need just the right combination of natural features,” she said.
“You need wind, you need waves, and you need floodwaters.”
Dr Willis says the foam is caused by the presence of plant materials and algae.
As the water is shaken by the waves it creates the bubbles and foam.
Dr Willis says the foam does not usually remain in place long enough to have a harmful effect on the environment, but that it can, when combined with muddy water, reduce the amount of light making its way through to seagrasses.
“It is only harmful if the water washed into the water is polluted, but the foam is not formed because of pollution,” she said.
Foam has been seen on several occasions since floodwater started to enter Encounter Bay.
The Department of Primary Industries confirmed this week that the ban on taking bivalve molluscs, including pipis (Goolwa cockles), from Goolwa and Middleton beaches would stay in place until further notice.
The ban was put in place on 12 January after the detection of E. coli in pipis above the level considered safe for human consumption.
The ban includes the entirety of Goolwa Beach, from the Murray Mouth to Middleton Point, near Mill Terrace at Middleton.