Mysterious foam and dead fish wash ashore as surfers report illnesses

People visiting Southern Australia may be in for a surprise as mysterious foam and dead fish are washing ashore.

A microalgal bloom created by unusual weather conditions resulted in the foam spanning over hundreds of yards of coastline, the Associated Press (AP) reported.

The bloom may cause algae to grow out of control, "producing toxins that can kill fish, mammals and birds," according to the National Oceanic and Atmospheric Administration (NOAA).

"While we were out there, we started coughing," local surfer Anthony Rowland told the AP.

"Lots of people reached out - so many people have said [they've] had exactly the same symptoms," Rowland added.

The severity of the blooms depends on factors such as the structure of the coast, runoff, oceanography, and other organisms in the water, according to the NOAA.

The Associated Press contributed to this report.