Blue-green algae: hazard to the environment
Mon 10 November 2008
Joshua Cummings, Journalism Major
I’m cautious as I creep past a sign telling me “lodge stayers only”. I walk between trees that tower metres above my head and look at the little hideaways tucked among them.
Something gives me the impression the owner of this place does not want people to know it is here.
It is almost like a hidden forest paradise.
I watch a bird hopping from tree to tree chirping away, and take out my camera to get a shot of him. He bounds around for a while, almost as if teasing me.
When I finally think I have a good shot he cheekily flies away.
I continue walking and come to a large lake.
I notice it is swarming with a thick green sludge floating on the surface. Later I venture to the opposite side.
I see this large buoyant mass seems to cover the entire lake. It does not seem to worry the pelicans mingling in a group on the helicopter pad across the way.
Then I notice a sign which says in big bold capital letters “RECREATION HAZARD”. Beneath it says “blue green algae”. The predominant life form in the lake now has a name.
Wisconsin Department of Natural Resources says blue-green algae is also known as cyanobacteria, and that a bloom is defined as a buoyant layer which floats to the surface.
The large body of water, Lake Baroon, is the major supplier of raw potable water for Caloundra City and Maroochydore Shire Councils in Queensland.
The Burnett Mary Regional Group says the lake was built in 1990, and in that year suffered its first algal bloom.
Anabaena algae had found its way into the dam soon after it was completed, due to runoff from urban, residential and agricultural land.
Lake Baroon ranger Shane Watson believes the recent accumulation of algae results from a similar cause.
“There’s been constant rain over the last 12 months, it’s all the nutrients being washed into the dam off a lot of the properties,” Mr Watson says.
Catchment supervisor Murray Dunstan says the algae blooms have been recurring for quite some time.
“Baroon Pocket Dam has a consistent algae bloom that varies in intensity throughout the seasons,” Mr Dunstan says.
“A large proportion of the nutrients entering the dam are attached to fine sediment particles that have eroded from the land and creek banks upstream of the dam.”
Mr Dunstan also says the dam looked particularly green this year, due to a persistent algae bloom since the dam underwent its annual mixing event in July.
Blue green alga grows when the water is warm and enriched with nutrients such as phosphorus or nitrogen.
Griffith University Microbial Ecology Research Group’s Peter Pollard believes the best thing for the environment is to get rid of the blue-green algae as soon as it appears.
"Blue-green algal blooms are a natural process in any aquatic ecosystem,” Dr Pollard told the ABC.
“It's just that a few of them are toxic and if you get one, you want to get rid of it.”
Mr Dunstan believes the blooms will not remain forever.
“The majority of dams in South-East Queensland ‘turn over’ in the winter months, due to the cooling of the ‘nutrient poor’ surface waters which mix with the ‘nutrient rich’ bottom layer,” Mr Dunstan says.
“This natural occurrence pushes nutrients towards the surface which feed the algae bloom.”
Wisconsin Department of Natural Resources says reducing the amount of nutrients that wash into the lake will eventually reduce the frequency and intensity of blue-green algae blooms.
However, there may still be large amounts of nutrients in the sediment at the bottom of the lake which could continue to serve as food for the blooms.
Mr Watson believes the best way is to stay out of the water while the blooms are present, and that blooms also affect fish in the environment.
“It will eventually dissipate as the season progresses,” Mr Watson says.
“I do believe this is probably the worst it’s been”.
“The algae accumulate in the organs, so anybody catching any fish in water like this should be cleaning the organs out.”
According to the World Health Organisation, the organs are where most accumulation of toxins occurs.
The water also can be harmful to humans due to the toxins released by the blue-green algae.
Baroon Pocket Dam is currently experiencing high levels of blue-green algae, and people have therefore been advised not to come in contact with the water.
“At the moment we have actually closed the area for swimming, but people are still allowed to boat,” Mr Watson says.
According to Wisconsin Department of Natural Resources, blue-green algae are capable of releasing multiple forms of toxins which are harmful to humans.
The first are known as dermatotoxins and gastrointestinal toxins. These toxins can cause skin irritation, allergies, rashes, asthma, headaches, fevers and nausea.
The second forms of toxins are known as hepatotoxins and cytotoxins, which affect the liver and other organs. They can cause headaches, anorexia, vomiting, chromosome loss and DNA-strand breakage.
The third form of toxins are neurotoxins. Neurotoxins affect the central nervous system, and can cause seizures, paralysis and respiratory failure.
The Burnett Mary Regional Group voiced its concern regarding elevated levels of nutrients and phosphorous, which have continued to cause blue-green algae blooms to occur in Lake Baroon.
University of the Sunshine Coast student Andrew James has visited the lake on numerous occasions.
“The algae was quite thick...like green soup,” Mr James says.
“It was so thick it was dripping off my paddle like seaweed at times.
“I did get concerned about water splashing onto me and possibly getting into my ears, so I turned around after paddling about 50m.”
Dunstan explained over the past 16 years, 95 individual water quality improvement projects have been performed.
“The majority of these projects have helped to reduce erosion in the Lake Baroon catchment,” Mr Dunstan said.
“The best practice, most cost-effective method to reduce erosion and associated nutrients at a catchment scale is through the use of riparian vegetation and other soft engineering options, for example the introduction of large wood.”
Mr Dunstan also explained vegetation within a riparian zone can slow the movement of water and cause sediment, along with attached nutrients, to be deposited on the land before they can reach the stream channel.
“We aim to continue this work into the future to mitigate the risks to water quality in the long term,” Mr Dunstan said.
Mr Watson also says that the many tests conducted have indicated that the algae is non-toxic, and that even if there were toxins in the water, they would all be filtered out by the Lake’s treatment plant.
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Submitted Comments
Thank you for this informative and well-presented article, Josh. As a Tweed Heads Senior Citizen, I found the material most interesting and easy to follow. Am looking forward to reading more of your work, and to gaining a better understanding of issues of concern to this paradise we share north and south of Brisbane.
Lorraine Shuker