Australia's plankton population, a vital key in the human food chain, has moved 300 kilometres south in 30 years, new research has found.

Scientists attributed the shift to the warming oceans caused by climate change.

In some regions there was also a shift from cold-water to warm-water plankton species.

Key points: Plankton produces about half the oxygen humans breathe

Plankton produces about half the oxygen humans breathe Determines numbers of fish, marine mammals and turtles in a region

Determines numbers of fish, marine mammals and turtles in a region Populations have moved 300km south in 30 years

Populations have moved 300km south in 30 years Scientists attribute move to climate change

The Plankton 2015 report from the CSIRO is based on data from the Integrated Marine Observing System (IMOS), which looks at why plankton is important to ocean health.

The report's lead author, Dr Anthony Richardson, said how much plankton there is, and where it is, determines how many fish, marine mammals and turtles are in the sea.

"The key findings are that plankton, which are really important to people, are changing and changing really in response to climate change," he said.

"Plankton are responsible for about half the oxygen we breathe, and are critical to the marine food web.

"They can impact human life."

The report compiles information from plankton studies and data sets from across Australia giving a snapshot of the climate, the state of global fisheries and marine ecosystem health and biodiversity.

Researchers found that on the east coast of Australia, plankton had moved southward 300 kilometres over the past 30 years.

Jellyfish thriving under changed conditions

Dr Richardson said off the coast of Tasmania's Maria Island, there had been a shift from cold-water to warm-water plankton species.

"Warm-water plankton is smaller and some fish, seabirds and marine mammals just don't like the taste," he said.

"The main food for young fish is plankton, and so as the climate warms we're getting this tropical plankton which is very diverse, but small, moving further south and that is bad for fish spawning and breeding."

He said more carbon dioxide in the atmosphere was leading to more acidic oceans.

"Although there is evidence of thinning shells in sea butterflies in northern Australia over the past 30 years, there is no general decrease in abundance of shelled animals and plants," Dr Richardson said.

Dr Richardson said the report delivered some good news on jellyfish.

"Whilst in various parts of the world that have been heavily polluted or fished there have been massive jellyfish blooms, there is no evidence that jellyfish abundance has increased in Australian waters," he said.

Information from Plankton 2015 will be used in the next Australian State of the Environment report to highlight how our marine estate is changing.