Spawning coral set to impress

A spectacular event is about to occur off the WA coastline, but you’ll have to be in the right place at the right time to see it happen.

The annual mass spawning of corals is about to occur along the Dampier Archipelago, Ningaloo Marine Park and Abrolhos Islands for just four days from March 27.

Department of Environment and Conservation marine science program leader Chris Simpson said the event occurs over the period of the lowest tidal range, seven to 10 nights after the full moon.

“This fascinating event in the coral reproductive cycle looks something like a pink underwater snow storm, and it attracts many divers and photographers each year,” Dr Simpson said.

“The coral spawning usually occurs at night, usually on an ebbing today, beginning about an hour after sunset and continuing for two to three hours.”

Dr Simpson said these events had occurred several times on WA coral reefs in the past and were important natural disturbances on our reefs. He said coral spawn slicks were often confused with large algal blooms.

“These blooms are usually a reddish-brown in colour, earning them the name ‘red tide’, and are often confused with the pink coral spawn which also floats on the sea surface.”

He said water temperatures along WA’s coastline over the past few months had been usually high, causing coral stress that results in coral bleaching and mortality if it persists.

“The higher than usual ocean temperatures are mainly due to the La Nina weather pattern which causes the Leeuwin Current to flow strongly along WA’s coast bringing warm water further south than usual.

“La Nina is often also associated with calmer weather in WA, which reduces flushing of lagoon waters causing further warming of shallow, coastal waters by the sun.

“If calm conditions occur during the coral spawning period this year it will increase the risk of coral spawn slicks forming on the ocean surface reducing oxygen and causing mortality in coral, fish and other reef biota.”

DEC is calling for people who see coral slicks, distressed, floating or washed up fish or bleached corals, to take photographs and record the time, date and location of these observations and pass this information onto their local DEC office.