South Australian government officials say they have seen the “best signs” in a “long time” in the latest round of algal bloom monitoring.

Marine scientist Mike Steer confirmed on Thursday that the latest results were “fantastic timing” ahead of peak summer temperatures.

“Looks like positive signs — the best signs we’ve seen for a long time,” Mr Steer said.

“If you go back to mid-October when we were experiencing cell counts in the millions and high levels of chlorophyll A.

“The persistence of Karenia species and a whole heap of dead fish washing up — we’re very much in a different space now along the metropolitan coast.”

Professor Mike Steer - man with shoulder length hair stands at podium during press conference

Professor Steer says the latest testing results have been the best authorities have seen in a long time. (ABC News: Lincoln Rothall)

Mr Steer said the latest results showed all 21 metropolitan testing sites recorded no or low levels of Karenia species.

“There’s a couple of residual spots offshore that have elevated counts, but they seem to be relatively moderate,” Mr Steer said.

Zero levels were recorded at nine metropolitan sites, including Port River St Kilda Boat Ramp, West Lakes Exit, Henley Beach Jetty, Glenelg Jetty and O’Sullivan Beach Boat Ramp.

A handful of people near a jetty at a beach. Swimming flags are in the foreground.

Karenia cell counts were zero at Henley Beach this week. (ABC News: Genevieve Blandin de Chalain)

The remaining metropolitan sites recorded levels ranging from 100 to 6,000 cells per litre.

Zero or low levels of Karenia were also detected across Eyre Peninsula, Yorke Peninsula and the Fleurieu Peninsula.

Mr Steer said elevated levels were however detected at one regional site — Emu Bay Jetty on Kangaroo Island — which will continue to be monitored by authorities.

Reduction in fish kills

Professor Steer said there had been a decrease in the number of fish kills reported.

“We’re starting to see a decrease particularly in the last week or so, you will recall we had a whole heap of Leatherjackets dominate a couple of weeks ago,” Mr Steer said.

“We’re not seeing that consistently happening — so, there’s another good sign.” 

Fish swimming in clear blue water among the wreck of a ship

Authorities say there’s been a reduction of fish kills reported. (Supplied: Lukasz Halbryt)

The marine scientist added that authorities were starting to see Karenia species being overtaken by other species.

“The ones that we would expect that are there in natural numbers are the diatoms that are starting to have a more prominent role in our ecosystem — which indicates that it’s rebalancing,” Mr Steer said.

When asked whether swimmers should be concerned swimming at beaches in the warmer weather Mr Steer said, “perfectly clear, they should not be worried”.

He said despite the positive signs in relation to Karenia species, there were other species authorities would be monitoring.

“Will emphasise however that there are a number of other species in the mix, so we still need to be cautiously optimistic about the future, particularly as we roll into the upwelling season in early January, February and March,” he said.’It’s beautiful out here’

Henley Beach was scattered with people today, some of whom commented on the quality of the water.

“It looks very very clean now — very good compared to what it was,” beachgoer Annette Abilmouna said.

“We’ve got visitors from Canada, so I’m glad it cleaned up right at the right time.”

A boardwalk along a beachfront.

Those at Henley Beach on Thursday said the water was much clearer. (ABC News: Genevieve Blandin de Chalain)

Phillip Freeman, a tourist from the United States, said he had swum at Adelaide beaches three times since arriving.

“One day I was a little itchy but that probably subsided within an hour of getting out, so totally safe,” he said.

“I was a little conscious about it [the algal bloom] for the initial swim, but it wasn’t an issue.

“It’s beautiful out here, so you’ve got to come and enjoy it.”

Fellow beachgoer Veronica Vuong said she would still have to think before jumping in the water.

A mum with her two kids on a grass patch near a beach.

Veronica Vuong with her children at Henley Beach. (ABC News: Genevieve Blandin de Chalain)

“I guess I’d probably still be a bit cautious to start with, but looking that there are people out there swimming now I guess that just gives you a bit more confidence,” she said.

“My family and I do do a lot of walking along the beach from Grange to Henley, so initially the smell and seeing the sights probably did kind of affect us from coming down as often, but not so much now, I don’t think.”