A grim outlook for global fisheries and marine environments has been outlined in a study done by University of Adelaide researchers.

Published in the journal Proceedings of the National Academy of Sciences, their analysis finds ocean warming and acidification are likely to reduce the diversity of marine species.

"Our large-scale analysis suggests that many species will show a decrease in abundance, as well as diversity," Associate Professor Ivan Nagelkerken said.

"We looked at how climate change might affect marine ecosystems and species in the near future."

He said researchers were a little surprised to find much the same impacts when they modelled short-term stressors and longer-term ones.

"We didn't expect that longer-term studies would show equally detrimental effects," he said.

"We found that when you look at single stressor effects — only global warming or only global acidification — for some species you see no effect, for other species you see a negative effect, but when you combine these stressors you usually see an even worse effect.

"That's understandable because many species can cope with one stressor, but when you start adding multiple stressors that's where things become difficult."

Professor Nagelkerken said marine life already had been affected over recent years by polluted waters, sewage dumping and overfishing, and climate change would add to the woes in the years ahead.

"Very few species will be able to cope with such conditions," he warned.

"We also found it's much more likely that animals higher up the food [chain] — bigger predators and species — will be more affected by climate change than other species at the bottom.

"Some species might benefit a bit — primary producers like plankton and algae — but the bigger fishery species probably will not."

The researchers forecast acidification would lead to a decline in dimethylsufide gas production by ocean plankton and said that gas helped cloud formation and control of the Earth's heat exchange.

"There will be a species collapse from the top of the food chain down," the study's authors warned.

They said there seemed little scope for many marine species to adapt to the changes ahead.