The water quality at South Australia's Adelaide beaches is now being questioned and might be subjected to quality testing following the surge of carcasses of dolphins, fish and penguins that have washed ashore in the recent days.

At least 16 dead dolphins, two penguins and thousands of dead fish, along with an unusual amount of sea grass have washed up during the past month.

"There is no doubt that we have a water quality issue on a grand scale in the Gulf of St Vincent," Vic Neverauskas, Biosecurity SA manager of aquatic pests, was quoted by Adelaide Now.

Currently conducting tests seeking to know the cause of deaths of the specific marine lives, Mr Neverauskas said they suspect the fish deaths could be due to the algal blooms. But the cause of deaths of the dolphins and penguins could not be determined yet.

Catherine Kemper, South Australian Museum's curator of mammals, meantime said they have conducted initial tests on the dead dolphins, but results also remain inconclusive.

"There was E. coli identified near the blow hole of that animal and it didn't look 100 per cent inside either so there was some evidence that something was going on in terms of pathology inside," Ms Kemper was quoted by ABC.

"In other parts of the world, fish and dolphins have died as a result of biological toxins entering the system and these happen when you have things like red tides and algal blooms."

"We wouldn't normally do testing for this but we will this time."

Scientists of the state government are likewise conducting separate tests on the dead fish for signs of algae to confirm suspicions it was the main cause that led to the surge in the numbers of dead marine life washing up on Adelaide beaches.