Spawn­ing co­ral could help re­build parts of the Great Bar­rier Reef

Whitsunday Times - - FRONT PAGE - Clau­dia Alp clau­[email protected]­sun­day­

AN IN­CREASE in co­ral spawn­ing around Day­dream Is­land could help re­store the Great Bar­rier Reef over time.

The highly an­tic­i­pated an­nual event be­gan in Novem­ber, about 3–5 days af­ter the full moon.

Day­dream Is­land ma­rine bi­ol­o­gist Johnny Gaskell has wit­nessed co­ral spawn­ing on the fring­ing reefs around the is­land for the past five years.

He said the method of re­pro­duc­tion could help re­build other parts of the reef, de­pend­ing on the cur­rent.

“The im­por­tance of it here ob­vi­ously is be­cause some of the north-fac­ing bays im­pacted by Cy­clone Deb­bie are lack­ing the co­ral colour they had due to storm dam­age,” he told the Whit­sun­day Times.

“The great thing about this type of re­pro­duc­tion is that spawn­ing can re­pop­u­late other ar­eas in the re­gion. So the spawn­ing at Day­dream Is­land could help re­pop­u­late some of the co­ral at Blue Pearl Bay, for ex­am­ple.

“It’s de­pen­dant on where the cur­rent car­ries it.”

Mr Gaskell said he saw more co­ral spawn­ing around Day­dream Is­land this time than there was last year, with the most sig­nif­i­cant day be­ing Novem­ber 27.

But af­ter div­ing in about 80 sites around the Whit­sun­day is­lands, there were more pos­i­tive signs, he said.“There is less co­ral at the sites we go to, due to Cy­clone Deb­bie, but there are still quite a few good sites of both hard and soft co­ral,” Mr Gaskell said.

“We’ve seen some real pos­i­tive signs the past cou­ple of years.”

The co­ral spawn­ing, which hap­pens once a year, in­volves colonies and species of co­ral polyps si­mul­ta­ne­ously re­leas­ing their tiny egg and sperm bun­dles into the wa­ter.

The spawn­ing oc­curs af­ter a full moon and when ris­ing wa­ter tem­per­a­tures (usu­ally 26 de­grees or above) have stim­u­lated the mat­u­ra­tion of the ga­metes (eggs) in­side the adult co­ral.

The day length, tide and salin­ity lev­els also ap­pear to be fac­tors in de­cid­ing when the event will take place.

How­ever, even if the co­ral spawn­ing does spread to other sites, it’s un­likely there will be a no­tice­able change any time soon.

Mr Gaskell said it could be months be­fore polyps formed and much longer be­fore they be­came vis­i­ble to the hu­man eye.

“It could take over a year be­fore the species we’re likely to see from spawn­ing can be eas­ily recog­nis­able,” he said.

“It’s dif­fer­ent de­pend­ing on the species of co­ral but you start to see more colonies af­ter a few months.”

❝The great thing about this type of re­pro­duc­tion is spawn­ing can re­pop­u­late other ar­eas — Bi­ol­o­gist Johnny Gaskell

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