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Brisbane Times

'Jelly balls' may slow global warming

Geoff Strong | November 17, 2008

VAST numbers of marine "jelly balls" now appearing off the Australian east 
coast could be part of the planet's mechanism for combating global warming.

The jellyfish-like animals are known as salps and their main food is 
phytoplankton (marine algae) which absorbs the greenhouse gas carbon dioxide in 
the top level of the ocean. This in turn comes from the atmosphere.

Mark Baird of the CSIRO said salps were notoriously difficult for scientists to 
study in the laboratory and consequently little attention has been paid to 
their ecological role until recently.

Dr Baird was part of a CSIRO and University of NSW marine survey last month 
that found a massive abundance of salps in the waters around Sydney. They were 
up to 10 times what they were when first surveyed 70 years ago.

Different salp species are found around the world and attention is now being 
paid to what effect they might have on global warming.

They are also of interest because in the Southern Ocean near Antarctica they 
are thought to be displacing krill, which is a key food source for many marine 
animals, including filter-feeding whales such as the southern right and 
humpback. By eating the algae, the salps turn the algae and their carbon 
dioxide into faeces which drops to the ocean floor. They also take carbon to 
the floor with them when they die after a life cycle as short as only a couple 
of weeks.

This is thought to be a natural form of carbon sequestration similar to what 
scientists are trying to do with carbon capture from emission sources such as 
power stations.

Dr Baird said Australian salps, which grow to about half a centimetre, are 
biologically closer to vertebrates such as humans than to jellyfish because 
they have the rudiments of a primitive nervous system.

"They are interesting because they are the fastest reproducing multi-celled 
animal on the planet and can double their numbers several times a day."

Salps had in the past been considered of little interest because they had 
fairly low nutrient value and were insignificant as a food source.

He said this was a concern because as the Antarctic ice melted, they were 
replacing krill, which is a high-nutrient food

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