Algal Bloom: What you need to know
Our beaches and coastal regions are open for business and our seafood is to be enjoyed – experts tell us the simple facts about South Australia’s algal bloom.
Our world-class seafood and stunning coastlines are the heart of South Australia. While a natural algae bloom is presenting new challenges, our resilient fishing and tourism operators are working tirelessly to continue delivering the premium experiences our state is famous for. Now is the perfect time to rally behind them to support local jobs and safely enjoy the spectacular coastal regions that make us proud.
The algal bloom continues to affect beaches and estuaries along parts of the state’s coastline. The bloom has harmed marine life as it has spread, concerning all South Australians.
There has been many theories and much misinformation across social media and other online platforms.
So, we asked the Executive Director of the South Australian Research and Development Institute, Professor Mike Steer, a marine scientist, to give us the facts.
WHAT IS THE ALGAE?
Karenia mikimotoi is a type of microalgae, or dinoflagellate, that exists in the phytoplankton.
Thousands of dinoflagellate species exist but only a few are harmful, including the karenia species. In low levels, it does not pose serious problems, but when environmental conditions favour its growth, it can become a harmful algal bloom.
South Australian Research and Development Institute executive director Professor Mike Steer, below, says karenia mikimotoi naturally exists in low levels in SA’s ecosystem, so it was not recently introduced, nor can it be eradicated.
“In fact, microalgae are the first part of the food chain in the marine ecosystem and Karenia are always there,” he says. Prof Steer says South Australia has previously experienced harmful algal blooms, such as in 2014 at Coffin Bay that lasted for three months.
WHAT CAUSES ALGAL BLOOM?
A harmful algal bloom forms when certain weather conditions occur concurrently, creating the perfect environment for it to flourish. In this instance, still waters in calm weather, warm water temperatures, nutrients in the water and an abundance of sunlight enabled the algae to reproduce rapidly.
The algae are also mixotrophic, which means they can source energy from both the sun, through photosynthesis, as well as through dissolved organic and inorganic matter (nutrients).
“One cell can reproduce to two cells every two to three days, and those two cells become four, etc, so you can imagine how quickly they would bloom when the conditions are right – and that’s what’s happened,” Prof Steer says.
“It makes it incredibly resilient and difficult to deal with.”
WHY HAS THE ALGAL BLOOM APPEARED?
Prof Steer says knowledge of the ideal conditions under which the algae thrive points to several factors. “We had the Murray River flood, which pushed a whole heap of nutrients into the ecosystem,” he says.
“Then, we had this incredible upwelling, the likes of we haven’t seen for 25 years, which also input quantities of nutrients and resuspended algae.
“Then, we had a marine heatwave of the likes we haven’t seen for 40 years, where sea surface temperatures were about two and a half degrees higher than usual.
“I think the conversion of those three unprecedented ecological events really set up the foundation for this species to proliferate in the environment.”
He says harmful algal blooms do occur in other Australian waters and across the world but they do not normally endure for such a long time. Prof Steer believes the unique oceanography of Gulf St Vincent and Spencer Gulf is contributing to the longevity.
“We expected this one to disappear with the changing environment in the shift into winter conditions, but it’s hung on, and it’s entered and proliferated in our gulf systems,” he says.
“It is currently circulating around the gulfs in a clockwise pattern, consistent with the movement of the currents.”
From the southern Fleurieu Peninsula region, the algae pushed north, first to the western side of Gulf St Vincent and then followed the circulatory pattern around to metropolitan Adelaide. Similarly, it has pushed into the western side of Spencer Gulf.
WHAT ARE THE EFFECTS OF THE ALGAL BLOOM?
For humans, the algae can be an irritant. Affected sea spray or water can cause temporary problems such as coughs and itchy eyes. Marine life can be affected in many ways. Air-breathing marine animals, such as dolphins, can also be irritated by the algae, Prof Steer says. Algal blooms may limit their food supply, possibly leading to starvation.
Excessive algal growth can inhibit sunlight from reaching underwater environments, potentially resulting in the death of marine plants. The algal bloom may adversely affect marine organisms that rely on gills to breathe, potentially causing suffocation and oxygen depletion and their subsequent appearance along South Australia’s coastline.
HOW DOES IT KILL FISH?
The algae can clog and damage the gills of marine life, such as fish and stingrays, so they cannot breathe. These animals can also struggle to breathe from a reduction in oxygen in the water.
While collectively, the algae produce a lot of oxygen, when algae cells die off, they decompose, which draws oxygen from the water. Other marine life, such as dolphins, do not use gills to breathe so are not suffocated or killed directly by the algae.
HOW LONG WILL THE ALGAL BLOOM LAST?
At this stage, scientists are unable to predict how long the algal bloom will last or how it will respond to changing conditions.
“What we’ve seen through tracking this harmful algal bloom, is that when conditions become unfavourable, it tends to decrease in its intensity,” Prof Steer says.
“When we think nature is getting on top of it, a couple of days later, we’ll get clear conditions and calm days with warm sunlight and it bounces back.
“Part of the problem with this algae is that it’s incredibly versatile.”
WHAT ACTIONS ARE THE SA GOVERNMENT TAKING?
The South Australian Government, including SARDI, the Department for Environment and Water and the Environment Protection Authority, is routinely tracking the algal boom, including using satellite imagery and testing water quality, to inform the community on developments in real time.
A $28 million support package has been announced by the State Government, providing business support, community support and clean up, communication including public information sessions, and science and research support.
With this support, SARDI will research the algae further, including its potential to predict future occurrences.
The State Government is also closely consulting with international experts in multiple countries who have dealt with algal blooms.
Meanwhile, the State Government is also investigating the impact the algal bloom is having on marine diversity as well as commercial, recreational and culturally significant seafood resources.
It includes identifying methods to help these resources recover, as well as how long it takes for them to do so.
Already, the State Government is working with community groups to establish and restore native oyster reefs to help nature “sop up” the bloom.
“Historically – 100 years ago or more – we had extensive native oyster reefs throughout South Australia’s gulfs,” Prof Steer says.
“Oysters are an amazing creature and perform an essential role in the ecosystem as they filter the water and feed on the algae, cleaning the algae from the ecosystem.”
In the longer term, remediating seagrass will naturally restore the marine environment and help mitigate against future harmful algal blooms.
Early discussions are also investigating how to recover fish species, possibly in ways similar to the snapper restocking program that is addressing decline.
WHAT SHOULD BE EXPECTED NEXT?
Prof Steer says it is very hard to predict what will happen next or in future.
“That’s why it’s really important for us to invest in our science and research to get a handle on the key drivers that this particular microalgae is thriving on and how a changing environment would impact, or provide a level of forecasting of, future algal bloom events,” he says.
“We’re learning something new regularly with this particular species.”
Prof Steer encourages people to go online and visit algalbloom.sa.gov.au for the latest updates and information, including around mental health, financial support packages and advice on how to continue enjoying the beach and local seafood.
The website also provides information about upcoming community forums, open to anyone to ask questions or hear directly from experts.
He also hopes beachgoers will continue to remain vigilant and report dead fish they may encounter on South Australia’s coasts to Fish Watch by calling 1800 065 522.
Stranded or dead marine mammals, sea birds, turtles or other marine life can be reported by calling the Emergency Animal Disease.
Algal bloom is irritating, but our seafood is safe
The algal bloom has hit South Australia hard, but its effects on humans are limited, Chief Public Health Officer Nicola Spurrier says.
Deaths of marine animals, loss of livelihood for many South Australians and the impact on the mental wellbeing of the public are serious concerns.
But physical health of the population is not in danger, Professor Spurrier says. The species of algae – karenia mikimotoi – only has an irritant effect and does not produce a toxin harmful to humans.
Prof Spurrier compares it to pepper - safe to eat but nasty if sprayed in your eyes.
“It is an irritant,” she says.“It’s not toxic, it doesn’t cause an allergic reaction. It can make your skin or eyes itchy.
“On windy days, small particles can break off and be in the air and you might start coughing but it won’t trigger a reaction like asthma.
“The symptoms resolve quite quickly.”
SA Health’s advice is to avoid swimming if water is discoloured and foamy.
“Even if it’s not obvious, you go for a swim and find your eyes are a bit stingy, just hop out and wash it off,” Prof Spurrier says.
“It’s not going to cause any long-term damage.”
She is confident SA’s seafood is safe, because of rigorous shellfish testing.
“I can say very reassuringly that fish you buy in a shop, supermarket or restaurant is totally fine,” she says.
“Many people like going fishing and the fish they catch, the flesh, is fine. Crayfish, lobster, squid – they are all fine, but you must remove the guts and throw that away.
“The only thing you should not do is collect and eat your own bivalve molluscs – oysters, mussels, pipis or abalone. Buy those in the shop instead.”
Some shellfish farms were temporarily closed after testing found brevetoxins. This was the first detection in Australia of the toxin, which can cause vomiting and other symptoms if contaminated shellfish are eaten.
Brevetoxins are known from Florida where harmful algal blooms are dominated by karenia brevis, a different species than karenia mikimotoi.
“Algae grow in communities of different species, it can be a bit of a mixture,” Spurrier says. “The main one here is karenia mikimotoi.”
Bivalve molluscs like oysters are filter feeders, sucking through large volumes of water and concentrating tiny quantities of matter.
Within a short time, they expel brevetoxins naturally. Therefore, once cleared by testing, farms can reopen.
Fish, prawns, crabs and lobsters do not accumulate toxins.
While satisfied on toxicity risks, SA Health is nonetheless concerned about mental health.
As part of the algal bloom response, SA Health and Mental Health Commissioner Taimi Allan are developing initiatives for the public.
“When something we love – like the beach – is damaged, we can feel real grief,” Prof Spurrier says.
“Some people feel sad, some go through a denial phase, some get angry.
“Seeing the dead marine life is terribly confronting.
“And people understand this is an impact of climate change; this is our changing world.
“That is very distressing.”
Prof Spurrier encourages people to talk with friends and families – and to approach their GP or mental health services as needed.
It is important to seek accurate information, Prof Spurrier says.
“This is something we have never experienced before.
“We are collecting and re-evaluating information all the time.
“That’s what our scientists and marine biologists are doing.
“That information is being shared with the public via the community forums, the algal bloom website and dashboard and mainstream media.”
