Blue-Green Algae 101: Everything You Need to Know

So you’re looking into dam maintenance, and you’ve come across the term blue-green algae a lot. You might be wondering what blue-green algae is, why you need to watch out for it in your dam, and how you can make sure you won’t get blue-green algal blooms in your water.

If you are wondering about all of these questions, then you’ve come to the right place. Below, we have consolidated all the facts you need to know about blue-green algae blooms in one place to keep you, your family, and your livestock safe.

What is Blue-Green Algae?

Blue-green algae is actually not algae at all. It is a group of bacteria known as cyanobacteria, which create their energy by photosynthesising. Some types of blue-green algae produce toxins that can be harmful to human health, but not all types of cyanobacteria are harmful.

Blue-Green Algae Symptoms in Water Supply

The first step to identifying a problem with blue-green algae in your water supply is to know the visual identifiers of possible algal blooms. Symptoms and signs of blue-green algae in your water include the following.

• Water discolouration: If your water has turned blue-green, brown, or reddish, it might be that you have blue-green algal blooms in your water.
• Surface Blooms: You can often sport scums or mats on the surface of your water that may resemble paint, foam, or floating clumps. These are an accumulation of blue-green algae.
• Unpleasant odour: Sometimes, a blue-green algal bloom will cause an unpleasant, musty, earthy, or grassy odour in and around your water.
• Algal masses: Under the surface of the water, you may be able to identify masses of algae that reduce the water clarity.
• Dead wildlife and fish: If you’ve noticed that aquatic life and other animals keep turning up dead near and in your pond, it is possible they have ingested algal toxins.
• Poor water clarity: Algal blooms, no matter the kind, often reduce the clarity of the water and make it cloudy or turbid.
• Oily sheen: Sometimes, blue-green algal blooms can leave an oil-like sheen on the surface of the water. This is caused by certain surface-active compounds that the blue-green algal bloom produces.

It is always important to stress that if you have spotted any of these signs in your water source, you should avoid entering it until you have determined the actual cause. Blue-green algae can release algal toxins that cause gastrointestinal problems, issues for the nervous system and more.

Where is Blue-Green Algae Found?

Blue-green algae are found in a vast number of water sources, but there are some characteristics of the water body that can make it more prone to algal blooms. These characteristics include:

• Stagnant and slow-moving water
• Shallow water
• Warm water temperatures
• Nutrient-rich or eutrophic conditions
• Water bodies affected by urban run-off
• Retention ponds
• Reservoirs
• Farm ponds
• Lagoons and backwaters with limited water exchange

Even if your water body has one or more of these characteristics, it doesn’t definitely mean you’ll get a blue-green algal bloom. What it does mean, though, is that rigorous and regular inspections are required to prevent the formation of an algal bloom before it occurs.

What Causes Blue-Green Algal Blooms?

Like all forms of algal blooms in aquatic ecosystems, there usually needs to be a specific set of conditions before the algae forms a bloom. Blooms refer to the rapid reproduction and subsequent overpopulation of algae in your water body.

• Water with excessive nutrients, particularly phosphorous and nitrogen
• Water with little circulation or low flow rates
• Shallow waters that heat up quickly
• Increased water temperature, particularly in the summer months
• Use of fertilisers on agricultural land
• Improper waste disposal
• Industrial runoff
• Global climate change contributing to overall increased temperatures

It is important to note that algae is naturally present in almost all fresh water. Algal blooms occur under specific conditions and become a problem when they harm the aquatic ecosystem around them.

Is Blue-Green Algae Harmful to Human and Animal Health?

While there are algae in almost all water, some forms of cyanobacteria (blue-green algae) can release algal toxins that are harmful to both human and animal health.

Human health effects include:

• Skin irritation, including rashes
• Eye irritation
• Respiratory symptoms, like coughing and throat irritation
• Gastrointestinal symptoms, like nausea, vomiting, diarrhoea, and abdominal pain
• Neurological effects, including headaches, dizziness, and, in some cases, seizures
• Liver damage

Humans can be affected by blue-green algae if it is in contaminated drinking water, by swimming in contaminated water bodies, and even through the ingestion of fish or shellfish that have been exposed to cyanotoxins.

Animals that have been exposed to algae-affected water may show symptoms like coughing, laboured breathing, stumbling, weakness, lethargy, and seizures. Ingestion of blue-green algae-affected water is often fatal to pets and livestock.

How Can I Treat Blue-Green Algal Blooms?

Treatment of blue-green algae includes removing the conditions in which these algae need to thrive. This could include the mechanical removal of blooms by physically scraping them from the water’s surface. It might also include installing an aeration device to encourage more water circulation.

In some particularly difficult cases, it might be recommended that you use algaecide. However, we at Love My Dam only ever recommend this in very severe cases. Algaecide can have harmful effects on the entire ecosystem and may make it more likely that the blue-green algae returns.

Rebalancing the ecosystem is one of the best ways to treat a blue-green algae bloom. This can mean introducing competing species and even adding other bacteria that compete with the blue-green algae.

It is important to note that boiling algae-affected water is not considered a suitable method of treatment. If blue-green algae have affected your drinking water, boiling will not remove the algal toxins and other treatment is required. Avoid drinking water sources until the blue-green algae has been removed.

How Can I Prevent Blue-Green Algal Blooms?

Prevention of toxic algae is very similar to the treatment methods. This means it’s all about cutting off the conditions that make your surface water a perfect place for algae to grow and produce toxins. Prevention tips include:

• Nutrient management in and around water supplies, including proper fertiliser application, soil conservation methods, and crop covering
• Runoff control, like installing permeable pavement, green roofs, and vegetative buffers
• Proper treatment of wastewater
• Rotating livestock grazing to prevent overgrazing and soil erosion
• Proper mature and pet waste disposal
• Monitoring water quality and testing regularly
• Educating staff or family about the signs of blue-green algae and its causes

How Can I Test for Blue-Green Algae in My Dam?

Testing for blue-green algae can be done in a few ways. You may want to try an at-home method first to check whether the algal blooms on your surface water are blue-green algae or not. These methods include:

• The stick method: This involves pulling a stick through the floating scum on your water surface. If it comes up stringy, it is more likely you’ve got filamentous algae. If the stick comes up looking like it is covered in paint, blue-green algae could be the issue.
• The jar method: Fill a clear jar 3/4 full of your pond water (don’t overfill as algae can produce gas and lead to pressure in the jar). Leave the jar undisturbed in the fridge overnight. In the morning, if there is a ring of green on the surface of the water, blue-green algae is likely present.

It is important to remember that these at-home methods are not fool-proof. You should also always exercise caution when trying at-home methods. Always wear gloves and don’t enter the water.

If you want a professional testing kit that will give you a definitive answer on the presence of blue-green algae in your water supplies, then purchase our blue-green algae testing kit.

Conclusion: Blue-Green Algae

Blue-green algae can wreak havoc on your dam, so knowing the signs and the treatment methods is key. Put preventive measures in place now to prevent a bloom and ensure you educate those on the property about the signs.

If you need further advice on the right products to use for blue-green algae, then don’t hesitate to contact us today.