Large blooms of a naturally occurring marine microbe have been observed along parts of the Queensland coast, including around Magnetic Island. These blooms are a natural seasonal occurrence, typically appearing between August and October.

Known as Trichodesmium, the cyanobacterium is an important part of the Reef's food web, helping provide essential nutrients that support marine life.

Reef Authority Marine Scientist Paul Groves said that despite their unpleasant appearance and smell, the blooms can play a vital role in supporting Reef health.

• "Trichodesmium has an important role in the marine ecosystem, converting nitrogen from the atmosphere into nutrients that other marine organisms can use," Mr Groves said.

"As the blooms naturally break down, they release nutrients that can support the growth of seagrass, algae and plankton.

"This can provide benefits throughout the Reef's food web, from seagrass eaten by dugongs and green turtles to plankton that provides an important food source for fish larvae.

Mr Groves said seasonal winds, weather conditions and nutrient availability can influence the formation and movement of blooms.

• "Trichodesmium blooms can appear as brown, pink or reddish slicks on the water's surface and are sometimes mistaken for coral spawn or pollution," he said.

"While these blooms are a natural occurrence, people should avoid direct contact as they can cause skin irritation.

"Large accumulations of decomposing trichodesmium slicks in sheltered bays can also reduce oxygen levels in the water, potentially affecting fish and other marine life."

ENDS

Contact: Great Barrier Reef Marine Park Authority
Media Hotline: (07) 4750 0846 | media@gbrmpa.gov.au