Broulee Beach becomes bioluminescent during rare phenomenon

As the sun set on August 12, the shallows of North Broulee Beach lit up with bioluminescence.

The bioluminescence was likely caused by a "red tide", which is a dense bloom of dinoflagellates or marine plankton called noctiluca scintillans. These blooms can be caused by nutrients entering the ocean from nearby estuaries and rivers after weather events.

On the South Coast, slight rises in water temperature and north-easterly winds have historically resulted in bioluminescent displays at Jervis Bay, however there have been very few recordings of bioluminescence in the Eurobodalla.

Alone, the dinoflagellates will not illuminate, but if something stirs the water, it can cause a spectacular light show. Once the tides or wind changes, the plankton will disperse and the red bloom will disappear.

In high volumes, red tides can make shellfish dangerous to eat and should be avoided, but the bioluminescence can make for a striking light show.

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Eurobodalla Shire Council mayor Mathew Hatcher was alerted to the potential bioluminescence on Saturday and headed to the beach with his family after watching the Matildas beat France.

"I had no idea what to expect. I had seen it in pictures and once in Thailand, but I've never seen it in Australia," he said.

According to tourism business Jervis Bay Wild, the natural phenomenon is usually only found in Jervis Bay, Preservation Bay in Tasmania and Port Lincoln in South Australia.

Bioluminescence caused by the red bloom is notoriously hard to predict, but Mr Hatcher was lucky to spend more an hour experiencing the glowing display, watching light shoot across waves and lap onto the sand.

"It was going pretty hard when we first got to the beach. We walked along the water and it was like electricity running down the beach," he said.

He said about 300 metres of the beach was illuminated at the southern end of North Broulee Beach.

"It was a lot more vibrant near Broulee Island where the water was crashing into the rocks.

"The waves were coming in and each was carrying heaps of [plankton]."

He said for a few moments, they had the beach to themselves and were in awe of the phenomenon which is also known as "sea sparkle".