Scientific phenomenon makes beaches colder and greener

Out in the field: Oceanographer Doctor Daniel Harrison sampling a plankton bloom off Sydney.
Out in the field: Oceanographer Doctor Daniel Harrison sampling a plankton bloom off Sydney.

Residents might have noticed the beach surf is colder and the ocean greener, as a scientific phenomenon known as upwelling occurs along the coast.

The region is experiencing a string of north easterly winds dragging warm water off shore and pulling cold water from the depths to the surface, according to oceanographer Doctor Daniel Harrison.

"Basically when the winds are sort of persistently blowing from the nor-east its blowing water out from the coast and it’s bringing out really old and cold water from down in the deep," he said.

"The water is quite dramatically colder, you can see two things the water is quite a lot colder and will often be greener as phytoplankton will bloom from the extra nutrients coming up.

"It is likely to persist as long as the strong nor easterly keep blowing... about 200kms or so extending along the coast at the moment, from Coffs Harbour and south of Port Macquarie."

Dr Harrison said other parts of the world experiencing the weather event consistently, displayed better fishing stocks.

"Off the coast of Morocco and off the coast of Peru its very consistent and persistent, they have the biggest upwellings in the world," he said.

"And also the greatest fisheries in the world because of the nutrients coming up from down deep -  it's certainly good for fishing.

"I don't know about rushing out now for fishing but in the longer run the extra nutrients and phytoplankton are feeding the juvenile fish that were born this spring, so in a couple of years time those fish grow up.

"When you get strong upwelling events in other parts of the world you can see it in the fisheries record because you can see it in a stronger catch - but here right now is quite small by global standards.

"It simulates the whole food chain, brings in more predators and benefits all the way up the food chain."

Expert opinion: Oceanographer Doctor Daniel Harrison.

Expert opinion: Oceanographer Doctor Daniel Harrison.

Artificially created upwelling is also being considered as an potential option for use at the Great Barrier Reef.

"At the moment I'm working on ideas to try and save the GBR, I'm looking at these different ideas to help the reef survive climate change," he said.

"One of the ideas is that you try and create artificial upwelling, try and drag water from down deep up onto the reef when it experiences times of bleaching (from heat).

"The infrastructure and energy requirements are just huge so its not impossible to do but its a lower priority for research.

"We think there are some better ideas, for a lot less energy you can block out some of the sun."